Popular Science Monthly 1924-10: Vol 105 Iss 4

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Popular Science Monthly Most Wonderfully Illustrated Magazine in the World OCTOBER, 1924; Vol. 105, No. 4 25 cents a Copy; $2.50 a Year Published in New York City at 250 Fourth Avenue’ ae y Coming Next Month What is your radio problem ?—Broadcasting is passing rapidly from the realm .of the enthusiast to that of the public service utility, such as the telephone. Yet, unlike the telephone, radio has not yet been standardized to the point where you can use any receiver at any time, or any place, and expect to hear messages satisfactorily. The wide choice of receiving sets and hookups available, varying widely in cost, operation, and results for different localities, has brought about a serious problem for every person who is eager for the best that radio offers within his means. To help you solve your individual radio problem and to keep you abreast of radio progress—these are the main purposes of PoPpuLAR Science Monruty’s enlarged Radio Section, the most complete and useful of its kind published in any magazine. In this section next month, for example, an expert of the PopuLar Science INsTITUTE OF STANDARDS will tell you how to choose the set within your means that will give you the best service in your locality. Milton B. Sleeper, one of America’s foremost radio engineers, wrll de- scribe how you can build a short-wave receiver to pick up short-wave transmission that cannot be heard with the ordinary receiver. Jack 3inns will give you all the up-to-the-minute radio news. An understandable article on the A-B-C’s of broadcasting and recep- tion, scores of useful hints for everybody, and many practical con- struction articles, round out a useful radio service such as you cannot get anywhere else. Are you deaf, and don’t know it? Do you realize that one out of every 10 persons in the world suffers defective hearing in one or both ears? Simple ways to test your hearing, and to safeguard yourself against the tragedy of deafness will be told by a distinguished authority. The magic stuff called electricityx—What it will do for you, and what science is doing to enlarge its powers as your servant. Edward Mott Woolley’s remarkable story of a tremendous laboratory where men are harnessing its mysterious forces for the benefit of mankind. Milton B. Sleeper, dis- tinguished American radio engineer, who will describe in next month’s issue how to build a_ short- wave receiver And more than 200 other fascinating articles and pictures giving you all the news of science and invention, strange and unusual things people are doing, together with practical ideals for the automobile, the home, the home work- shop, and the use of tools and machinery. POPULAR SCIENCE MONTHLY Issued monthly. Single copy, 25 cent Yearly subscription to United States, its possessions, and Canada, $2.50; foreign countries, $3. Entered as ’ second- class matter Dec. 28, 1918, at the Post Office at New York under the act — March 3, 1879. Entered as second-class matter at the Post Office Department, Canada. Printed in U.S. A. C opyright, 1924, by the Popular Science Publishing Co., Inc. The contents of this magazine must not be reprinted without permission. In_presenting in its editorial columns numerous stories of new products of applied science, POPULAR SCIENCE MONTHLY does not under- write the business methods of the individuals or concerns producing them. The use of POPULAR SCIENCE MONTHLY articles, or quotations from them for stoc k-selling schemes is never authorized. H. J. Fisher, President; R.C. Wilson, Vice-President; O. B. Capen, Secretary and Treasurer In This Issue Page The Popular Science Institute of CLEA ES laa SD PR aaa eae The World’s Greatest Adventure. 31 33 By Maj. William N. Hensley, Jr., U.S.A A New Era in Automobile Construction By Edward Mott W olley Why the Fastest Racehorses Lose. . By Stanley G. Zinke, M. D. Rebuilding the Portal that Moses Entered. se Ae Are There Twins in Your F amily?. By H. H. Newman, Ph.D. Do You Sleep Too Much?......... By Donald A. Laird, Ph.D. The Most Accurate Man in America.. By Norman C. McLoud Skilled Mechanics in Congress. .. He Photographs the Invisible By Fritz Blocki New Wonders in Giant Twin Star. .. Wky Animals Understand Me.... By Gilbert Girard New Uses for Photo- Telegraphy. By Newton Burke Keeping Abreast of Science......... The Largest Floating Drydock By S. W. Clatworthy Lights as an Aid to Happiness By M. Luckiesh World’s Smallest Plane............ Mooring Mast Supplies Helium Three-in-One Navy Plane.......... Wind-Tunnel Testa for Airplanes.... Map Made from 2000 Photos...... Racehorse Makes Flying Trip The Most Valuable Egg............ Bungalow Made of Newspapers... . Chemistry Aids Police............. The Prince of Wales in Butter Farm Wagon from Old Auto Fence of Spinning Wheels A Modern Noah’s Ark............ How a Queen Bee Travels.......... Four Hours’ Sunshine in Alaska.... Motorcycle as Power Plant......... Platform for Unloading Grain...... Four Drawing Instruments in One. . Six-Inen Slide Rule... 2... 5.0.0.0 Fumigating Vault for Furniture Electric Finger-Nail Polisher An Automatic Guard Lock New Mileposts in Radio By Jack Binns How to Build a Super-Heterodyne. . Coast-to-Coast Set for $15.25 By L. Grant Hector, Ph.D. Radio Hints for the Broadcast Fan.. How Broadcasting Works......... By Robert E. Martin Small Crane for Truck Wheels. . New Six-Wheel Army Truck. Portable Truck Scales..... New French Small Car. : Brooklyn Has Largest Generator. ere Bricklaying Made Easy............ A Useful Folding Ladder........... Oil Refinery on Railway Cars....... Viaducts for Traffic Relief.......... Traveling Lawn Sprinkler.......... Stories Revealed by Earth Strata.... Deaf Children Taught by Radio... : ightning in the Sand Dunes.... Giant Traffic Light. . aA as Brake Testing Instrument. Red ne Treeless Spots in the Forest. Sewing Machine Cabinet Se ee anc How Much Science Do You Know?.. New Freight Handling System...... Vest Pocket BrMBl... 2. oc cvcweece sc Betty SRE GOR, 2.5) 5 sie nre.os wise e 30's Useful Ideas for the Home.......... Save your Wife 10,000 Steps a Day.. By L. Porter Moore Keeping Your Car Free of Carbon... By E. B. Staples Ideas that Cut Garage Bills........ The Home Workshop...... 85 Better Shop Methods...... 90 ~ Pr mms ss NN 1 em He He Go Ge Do DO 76 And other timely articles and pictures If de Ar let th tio tig Cie dr in Wwe As

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J} 6 ~~ 9 ) ~ wt - a Ie I ~ a ae ee ee eee ee ee oe ee ae ae ae. ae If you think it can't be done then there is a sur- prise in store for you. in which the Boss often makes less money than some of the men under him. And you can—but read the remarkable letter below, received a short while ago by the National Salesmen’s Training Associa- tion from a Sales Manager who was inves- ligating this System of Training, with a view to increasing his own efficiency. The record of this student is in the Asso- ciation files, but it is no different than hun- dreds of other really amazing records of inexperienced men who have studied this wonderful System of Salesmanship Training. Tt is one profession, and only one, Why Salesmen Are Well Paid How would you like the opportunity to make more money than the man who em- ploys you? Sounds almost foolish, doesn’t it? Yet, the seemingly impossible feat of making more money than the Boss is being done regularly in the selling field. Many salesmen earn more money than the man or men above them. In some cases, they earn far more than the president of the Company. There is a good reason why the same abil- ity will com- mand a larger income in the selling end “I note in your literature the names of some of thc boys trom Kentucky and 1 -5 ~ee Indiana with whom I am well of vusiness acquainted. One of the boys tuan in other from Kentucky, by the way, broke in under me. While still a cub, and without my ag: wie dee, he took up the A. Course and it wasn't he before I got a jolt. His weekly pay checks were departments. The men in the shops making the goods, and even larger than my own. “His increased earnings made me question him and it was then he admitted he was studying with you. The fact that he continued to succeed in such a big way ( aused me to write to you. do not envy this man in the slightest de gree, but I do want to say that if your train- ing could develop this par- ticular man into a high-class salesman, as it has, then your course could almost make a wooden Indian into a sales- man. ‘Had you met this man when I did you would have hesitated about accepting his enrollment. I am _ free to admit he of all others has ta ike *n the conceit completely it of me when it comes to ug judgment on_pros- Salesmanship — tim- || the men in the office handling routine ac- counts and Cte 1G tS, can never be as vital to a business as the men out sell- ing — their ef- forts actually determine how much goods shall be made. Irvin “y; Bush, Founder and President of the Bush Terminal Company in an article in the American Magazine, said: Go through any industry and you will find the same grade of intelligence is better paid in the elling force than it is in any other depart- ment. To those men who must make money to take care of responsibility and support of S Jamily, I again say, ‘GO ELL.’ And op- portunities for selling jobs are ten to one in other jields.”’ POPULAR SCIENCE MONTHLY aking More Money Than Thek 3 State of Illinois County of Cook Secrets That Make Master Salesmen From greenhorn to Star Salesman in next to no time sounds almost too good to be true. Yet, the National Salesmen’s Training Asso- ciation performs this wonderful transforma- tion for thousands year after year because it teaches the real secrets of salesmanship. Ward returned from France broke, un- trained. Last month he earned $1,350 as a sales- man. H. D. Miller, another Chicago boy, was mak- ing $100 a month as stenographer in July, 1922. In September, 3 months later, he was making $100 a week as a salesman. W. P. Clenny, of Kansas City, Mo., stepped from a $150 a month clerkship into a selling job at $500 a month. He is making $850 a month now. M. V. Stephens, of Albany, Ky., was making $25 a week. He took up this ara and now makes five times that much. J. H. Cash, of Atlanta, Ga., exchanged his $75 a month job for one which pays him $500 a month. O. H. Malfroot, of Boston, Mass., stepped into a $10,000 position as a SALES-MAN AGER—so thorough is this train- ing. All these successes are due to this easy, fas- cinating and rapid way to master certain invincible secrets of selling. Why did these men—farm hands, mechanics, bookkeepers, clerks, railroad men and routine workers in every walk of life—attain such quick success. The answer is as simple as A B C. There are certain ways of doing and saying things in sell- ing—certain ways to approach different types of prospects to get their undivided attention, to stimulate interest — certain ways to overcome objections, batter down prejudices, outwit com- petition, and make the prospect act. Once you know these vital things—once you have acquired thes fundamental principles—big success awaits you in this fascinating field. Previous Experience Unnecessary It doesn’t matter what you are now doing for a living. If you can read and write and have average intelligence, there is a wonderful future awaiting you in the selling field. If you must make more money, if you want to attain a measure of financial independe nce, if you want to accomplish worth- while things, then let us send you all the facts about this remarkable System of Salesmanship Trainin ; and Employment Service, including a big, FREE, illustrated book, ‘‘Modern Salesmanship.”’ In this book you will find full details about the National Demonstration Method which gives you actual experience while studying, complete infor- I, J. E. Greenslade, President of the National Salesmen's Training Assooic+ tion, of Chicago, Illinois, state under oath, that between January lst, and Juno 30th, 1923, this Association received calle for 29,256 Salesmen. 09, : ° * we Meg seerived and sworn to before me cot od N lotary. mation about the N: S. T. A. System of Electives which enable you to go out and sell a line, fortified with proven plans and successful methods of Master Salesmen in the line or lines you choose to sell. Also tells how N. S. T. A. Free Employment De- partment helps you to select and secure a position as local or traveling salesman as soon as you are qualified and ready. Send Now for Proof and Free Book To fill out and mail the coupon below may prove to be tlic turning point in your career as it has for gotta It will not obligate OLDEST AND LARGEST thousands. ; you, though it may inspire you to 8p bse ap make a move in the direction of TRAINING bigger pay, more opportunities, ¢ and congenial work. Don't hesi- - tate. A good idea to get it into «atiowac sacesmens the mail right NOW. —— 2 4. ce) Stipe National Salesmen’s Training Association Dept.15-R, 53 W. Jackson Blvd., Chicago, III. National Salesmen’s Training Association Dept 15-R, 53 W. Jackson Blvd., Chicago, Ill. Please mail me Free Proof that I can become a Master Salesman and qualify for a good sales position. Also send your illustrated book, ‘‘Modern Salesmanship,”’ and particulars of membership in your Association. This is all free of cost or obligation. Name. ...- --- er

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POPULAR SCIENCE MONTHLY pi “Your Future in Electricity” This book tells you how you can make good in the greatest Field.of all- Electricity Get your FREE copy - Use the coupon American School, Chicago, U.S. A. Dept. E775, Drexel Ave. and 58th St. Send me a free copy of your special bulletin describing the wonderful opportunity for me in Electricity. This request puts me under no obligation. American Sidvaol The American School is not a money-ma corporation, but like resident schools and cc 2S, is chartered strictly asan“Educational Institution, not for profit.” More than 200 famous engineers and e -duca ators prepared the special instruction papers fo r students, For over a quarter of a century, Big E Educators and Business Men have recor the American School. They know that our long perience as an educational institution guarantees the best training at the lowest possible cost 1818 (R181818.8-8 8 OS: MRIS ee ee ee C088 lM MM ee ON NN MA 5

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aking leges, ution, ators neers, -nded 1g ex- ntees —_ Electrici ~the Big P iscalling YOU! POPULAR SCIENCE MONTHLY Field ty 3 \ ie Wh h Ny \ \ ; NY) \f\ Ze an \\ 1 |) alle : SYA WY i) lh \ Be an Electrical Ex EARN ‘£3500 to °10000 a Day Mr. Cooke: “sll When I start- =» ed your course ne Iwas acarpen- ter never earn- ; & ing more than am - $7.50aday. Now, thanks to your training, make frum $30to0$50 a day in busi- ness for myself doing elec- trical work. J.R.Morgan, Columbus, Ohio. In Business For Himself L. L. Cooke: From a $15 a week manI have become a suc- cessful electric- alcontractor. In the last eight months I have cleared more than $450 a month overand above all expenses. I can never thank you enough for what you did for me. Fred Fritschman, 3959 Amundson Ave., New York City. $9,000 a Year 4 Everything is “li, going fine now : and I am earn- ing about $750 a month, Again I must thank you for my suc- cess, It was you and your won- derful course that put me where I am. . .W.E. Pence, Albany, Oregon. Earns $30 to $50 What’s YOUR Future? Now you earn $20 or $30 or $40 a week. In the same six days as an Electrical Expert you can make $70 to $200 and make it easier — not work half so hard. Why then remain in the small-pay game, in a line of work that offers no chance, no big promotion, no big income? Fit yourself for a “Bossing” job— Be an “Electrical Expert” Today even ordinary Electricians—the “screw driver” kind—are making money—big money, But it's the trained man—the man who knows the whys and wherefores of Electricity — the “Electrical Expert” — who is picked to “boss” the ordinary Electricians — to boss the Big Jobs —the jobs that pay. $3,500 to $10,000 a Year Get in line for one of these “Big Pay Jobs” by enrolling now for my easily-learned, quickly-grasped, right-up-to-the-minute, Spare- Time Home Study Course in Practical Electricity. Age or Lack of Experience No Drawback You don’t have to be a High School Graduate — it isn’t even necessary that you should have finished the grades. As Chief Engi- neer of the Chicago Engineering Works, I know exactly the kind of training you need, and I will give you that training. My Course in Electricity is the most simple, thorough, successful and practical in existence, and offer every man, regardless of age, education or pre- vious experience, the chance to become, in a few short months, an “Electrical Expert’”’ able to make from $70 to $200 a week. Earn While You Learn With me you do practical work—at once. In my first few lessons I show you how to make money doing Electrical work in your spare time. (Over half of my students are paying for their course in this way.) I show you, also, how to get started in business for yourself and then I help you to get started. WORKING OUTFIT To do spare time work you'll need tools, etc. These I give you— FREE—a whole kit, including measuring instruments, a real electrical motor (no toy) and other things — the greatest value ever given by any School. pert a Year Your Satisfaction Guaranteed by a Million Dollar Institution I absolutely guarantee to return every penny paid me in tuition if, when you have finished my Course, you are not satisfied in every way with my instructions. And back of me, 1n my guarantee stands the Chicago Engineering Works, a million dollar institution. Nothing Like “Cooke” Training Anywhere **Cooke’’ training is different because it’s the most practical and most successful. It’s best because it’s backed up by the greatest Service to students ever known. It’s this Service plus ‘‘Cooke’’ training that makes the ‘‘Cooke’’ trained man the‘‘Big-Pay’”’ man everywhere. Become a ‘‘Cooke” Trained Man yourself, and earn $12 to $30 a day — $70 to $200 o weck—@3,500 to $10,000 a year. Investigate! Mail Coupon Get the Vital Facts. Let me send you free my bie new book on The Future of Electricity. Let me te you more about the big demand for *‘ Cooke’’ trained Electrical Experts. Dept.37, Sign and send me Coupon. L. L. COOKE, Chief Engineer Chicago Engineering Works, Inc. this Coupon for m FRE 2150 Lawrence Ave.. Chicago, Ill. # L. L. COOKE, Chief Engineer, Chicago Engineering Works, Dept. a 37, 2150LawrenceAve., cago, Ill. a Dear Sir: Send me at once full particulars of your Free Outfit Offer; also your Free book,T}e ‘* Vital Facts’’ of Elec- tricity,No obligation on my part. Name ry Address ¢, tion y

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<= <2 rt raeil AUTOMOBILES AND ACCESSORIES AUTOMOBILE Parts—Used parts for most any car at f factory list prices. —,. . Cc Inalmers, Chevrolet, Dodge, D p- obile, Oakland, Overland, Oldsmobile, Reo, Studebaker d many others, Send list of parts wanted. Century to Parts Co., 4105 Olive Street, St. Louis, Missouri. MONEY !—Silvering autolights, radiators, mirrors. finishing tableware, stoves, brass beds, etc. Outfits, oong free, Write—Sprinkle-Plater, Dept. 96, Marion, ana. MOTOR Owners—Carbon trouble banished forever. brmula $1.00. Albion Bayers, Box 52, Rutland, Mass. VULCANIZERS, tools, materials, supplies, tires, bes direct from factory. Méiller-Anderson Rubber orks, Anderson, Ind., Dept. P.S.-3. FORD ACCESSORIES SPEEDSTER fans—see “‘Red-i-Kut”’ ad. page 154.

MOTORCYCLES, BICYCLES, SUPPLIES DVERSTOCKED—200 Used Motorcycles. Must be id at once. We have Harley-Davidsons, Indians, mdersons, Excelsiors, Clevelands. Prices $25.00 Up. te for our Bargain List. Myerow Brothers, Dept. C, Berkeley St., Boston, Mass. DON’T buy a bicycle motor attachment until you get catalogue and prices. Shaw Mfg. Co., Dept. 4, lesburg, Kansas. SED parts for all motorcyles cheap. Schuck Cycle ., 1922 Westlake, Seattle, Wash. AVIATION HE American School of Aviation announces a new espondence course in mechanics of aviation. A prough training in practical aeronautics. American ool of Aviation, Dept. 674-B, 3601 Michigan Ave., icago, Illinois. OYS get a three foot model aeroplane free. Nothing sell. Write to Aero Shop, 3050 Hurlbut Ave., Detroit, chigan. AIRPLANE Engineering, under the Western Airplane poration method of practical home training, offers 1 a chance to be Successful and ome a Leader in 8 newest neuter. Written for the Airplane industry Airplane men, this Up-to-date Course is offered to 1 for the First time after ti training hundreds of successful chanics and Engineers. Write for Catalog. Western plane Corporation, Dept. P, Monadnock Block, cago. IRPLANES, Flying Boats, Motors, Aircraft Sup- s. New 80 H. P. LeRhone Rotary Motor, $77.50; loon Baskets, $50; OX5 Motor, $400; Zenith Car- etor, $12.50; Compass, $15; Unshatterable Goggles, nbo, $3.50; wide-vision $5; Leather Helmets, $4.50; rk + 40¢; 26x4 Wire Wheels, $6.50; Cord Tires, htly Used, $3: moderately Used, $2; new Tubes, $2: ane Fabric, 65c yd. Floyd Logan, 716 W. Superior, velanc MOTORS, ENGINES AND MACHINERY SONCRETE Building Block Machines and Molds. alogue free. —- Manufacturing Co., 307 So. rd St., St. Louis, Mo. {1OTOR Manufacturer's Surplus Sale. 4%HP. $8.50; P, $32.59; 1 HP, $54.50. 8 Volt Charging Generators, 50. Complete "Lighting Plants—Generators—Light chinery. Write for Catalog. Motor Specialties Co., fton, Penna. 1R. ADVERTISER: Ask to-day for a copy of the ick-Action Advertising Rate Folder.” It contains he really important facts which will prove interesting valuable to you. It also tells ‘“‘How You Can Use ular Science Monthly Profitably.’”’ You'd like to know, ldn’t you? Address your inquiry to: Manager, Clas- pd Advertising, Popular Science Monthly, 250 Fourth nue, New York. MACHINE TOOLS ARGAINS. No. 3% Garvin oe Ee Machine, 5.00. 20 Drill press, $50. 13” ’ Steptoe engine he, $125. Complete line machinery. Cincinnati chinery Supply Co., 217 E. Pearl St., Cincinnati, O. TR. ADVERTISER: Ask to-day for & copy of the lick-Action Advertising Rate Folder.’’ It contains e really important facts which will prove interesting valuable to you. It also tells “How You Can Use ular Science Monthly Profitably.’’ You'd like to know, ldn’t you? Address your inquiry to: Manager, Clas- d Advertising, Popular Science Monthly, 250 Fourth .. New York. MOD"™LS AND MOD"%L SUPPLI®S ULIT & Co., 625 Jackson, Chicago, Ills. Experi- Atal Machinists. Model Make Dies. Patterns. plete general Machine shop. Ex-Lamson. YE make working models for inventors and experi- tal work, and carry a complete stock of brass gears and el supplies. Send for catalogue. The Pierce Model ks, Tinley Park, Illinois. MODELS, Dies, Metal Stampings, Light Manu- uring. Modern Shop. Reasonable Prices. Osborne ister Compiny, Pearl Street, Cincinnati. WANTED PANTED: Light Machinery, Lathes, Drill Presses, el High Speed Gasoline and Steam Motors. Best Prices Paid. Motor Specialties Co., Crafton, Penns. GENCIES Wanted. Submit particulars. Grenada 8.. Manufacturers’ Representatives, Buxton, Deme- . British Guiana. ETECTIV ES needed everywhere. Experience un- Particulars free. Write, George Wagner, vernment Detective, 1968P Broadway, A } ANTED—Inventors’ Experimental work, wood, 1 patterns, machine work, rubber mill under one roof. rawings. Miller-Anderson Rubber Works, Ander- Indiana. Dept. P.S.-3.

POPULAR SCIENCE MONTHLY oe Making Opportunities for opular Science Readers Another $25.00 IN PRIZES To win one of these cash prizes is easy, and every reader is invited to enter this fascinating competition. Just write a letter of not over seventy words answering this question: — What Advertisement of “Money Making Opportunities” in this issue interests you most and why? Here are the prizes we will pay for the ten best letters answering the above question: — First Prize. . .... +. «$10.00 Second Prize ...... 5.00 Third Prize . a J s e a — 3.00 And 7 Prizes of $1.000each ...... 7.00 First read every one of the ‘‘Money Mak- int Opportunity” advertisements on,pages 6 to 26. Check the ones that interest you. Then read over the ones you have checked and decide on the one that in- terests you most. Then write a short letter, not more than seventy words, telling us why the advertise- ment you pick interests you most. Remem- ber that ten prizes will be awarded. You have a good chance of winning one of them. Be sure to mail us your answer before Oct. Ist. The prizes will be awarded, in the order of their merit, for the letters that are most interesting and best expressed. The names of all the prize winners and the letters that win the first two prizes will be printed in this column in the Decem- ber issue. Address your prize letter to Contest Editor POPULAR SCIENCE MONTHLY 250 Fourth Ave.; New York City

Last Month’s Prize Winners The First Prize of $10.00 goes to Norman Reynolds, Spruce Creek, Pa., for his letter on the advertisement of ‘“‘Money Making Oppor- tunities.”” Here is Mr. Reynold’s letter: Dear Sir:— The slogan of a well-known flashlight manufacturer is, ‘‘The light that says, ‘There a fag This phrase concisely describes the assistance rendered me by ‘‘Money a Opportunities.’’ Coming at a time when urgently needed expert chemical assistance, they pointed the way to the Doris Chemical Laboratories and said, ‘‘There it is.” Naturally I am most interested in this advertisement for it furnished a satis- factory solution to my problem. NORMAN REYNOLDS. Mr. Ralph M. Williams, Amherst, Mass., wins the Second Prize for the following letter regarding the advertisement of the R. J. Carnes Company. Here is Mr. Williams’ letter:— Dear Sir:— I looked over the various advertisements in ‘‘Money Making Opportunities’ and that of R. J. Carnes attracted. me the most. I hope to become a writer of fiction and the writing and reading of manuscripts would let me see the various forms of word- ing, etc. used by different authors. And then, of course, I could earn a little money toward a college education. RALPH M. WILLIAMS, The Third Prize goes to Carl C. Hill, Glide, Oregon. The winners of the other seven prizes are:— Mrs. A. J. Hagel, Hartford, Kans.: Charles M. Reynolds, Spruce Creek, Pa.; J. F. Riley, Wheeling, West Va.; Cornelius D. Vezin, Yonkers, N. Y.; S. D. Snavely, Wytheville, Va.; Mrs. S. M. Passmore, Butte, Mont. E. F. Sauer, Milwaukee, Wis.

Rate 30 Cents a Word. A 10% discount is pa al on all contracts for six consecutive insertions. Advertisements intended for the De- cember issue should be received by October Sth. RADIO AND SUPPLIES 68 STA NS on Crystal without tubes or batteries. You fellows who haven't tried my hook-up don’t know ait you are missing. te, Leon Lambert,' 670 Volut- sia, Wichita, Kansas. 2650 MILES Distance with one tube. Any Novice understands our § Simguaes Instructions, including. Pe Layout and Photo 2 Vesco Radio Co., Box PS 117 Oakland, Calif. - RADIO tubes, Dll, D12, UV199, UV200, eS $036. Dutch 2 rate tubes, D12, D200, D261 rystal set, Add postage. Radio Sales Co. = 58 North FRE St. Louis, Mo. RADIO Generators: 50J0v_100 watt, $28.50. Battery rging Generators, $8.50. High Speed Motors. Motor ae Sets all sizes. Motor Specialties Co., Crafton, enna, MR. ADVERTISER: ASk to-day for a copy of the “Quiek-Action Advertising Rate Folder.” It contains some really important facts which will prove interesting and valuable to you. It also tells ‘“‘How You Can Use Popular Science Monthly Profitably.’’ You'd like to know, wouldn't you? Manager, Classified Advertising, Popular Science Monthly, 250 Fourth Ave., New York TRADE AND TECHNICAL SCHOOLS tee TW OE So ee CO 0 oe ee $10 TO $20 r day. Practical courses in Sign- ore awe ainting—Decorating—Graining— Mar- bling—Paperhanging—Low Cost—Catalog Free. Chicago Painting ¢ heal, 157 W. Austin Ave., Chicaxo. Til. CHICAGO Technical College offers short, intensely practical courses in Drafting and Engineering—civii, mechanical, electrical, structural —Arehitecture, Buildin : Construction, Plan Reading, ete. Courses fitted to your needs. No time wasted. Instructors are experts. Gr: d- uates in demand at big salaries. Opportunities for part- time work while studying. Day and evening classics. 2ist year. Enter any time. No special preliminary training required. Low tuition—easy terms. Write tu S3-onge illustrated Biue Book describing opportunities pen to our graduates. Chicago Technical College, 23 Chicago Tech. Building, Chicago. BE a Bricklayer. Attend a school operated by Building Contractors. Three Months Day ou $75.00. Associ ated Building Employers, 128 A. B. E. Building, Grand Rapids, Mich. MR. ADVERTISER: Ask to-day for a copy of the “Quick-Action Advertising Rate Folder.’’ It contains some really important facts which will prove interesting and valuable to you. It also tells ‘‘How You Can Use Popular Science Monthly Profitably.” You’d like to know, wouldn’t you? Manager, Classified Advertising, Popul:r Science Monthly, 250 Fourth Ave., New York. FOR THE HOME HOME weaving—looms only $9.90. Big money in weaving is ram, carpets, portieres, etc., at home from rags and waste terial. Weavers” are rushed with orders. Send for free I loom book, it tells all about the weaving business and our wonderful $9.90 and other looms. Union Loom Works, 482 Factory St., Boonville, New York. i DFATHER regent ge $5.00. Build your own good profits selling your friends Clock works with aioe for old or new cases. Write — full particulars. Clock Co., Nicetown, Penn. GASOLINE lamps, lanterns and heaters. oe free. Little Wonder Mfg. io, Terre Haute, Indiana BEAUTIFUL - china, hae’ patterns, instruc- tions 25¢. Circul: ddy Kabinets, 2651 8th Avenue, New York, PURCHASE a beautiful Electric Fountain for your home at Jobber’s price. Walter L. Haanel & Co., 4521 Ravenswood Ave., Chicago. BURN Smoke. Save 20 to 50% of coal. Get cleaner, steadier heat with Crown Fuel Saver. You can quickly attach this inexpensive device to feed door of furnace. Works automatically. Guaran' to make fuel-saving of at least 20%, or money refunded. Write for booklet and soecal low price. CFSCO. 14 N. 10th St., Rich- mond, In MR. ADVERTISER: Ask to-day for a copy of the “Quick-Action Advertsing Rate Folder.” It contains some 7, important facts which will prove interesting and valuable to you. It also tells “How You Can Use Popular Science Monthly Profitably.’’ You'd like to know, wouldn’t you? Address your inquiry to: Manager, Clas- — Levering, Popular Science Monthly, 250 Fourth Ave., New

MANUFACTURING DIES, Tools and General Manufacturing. Models an manufacturing of new inventions our specialty. Log:in Machine Co., 126 S. Clinton St., Chicago, Ill. DEVELOPING ideas and manufacturing our spc- os Absolute = 33 years’ experience, wrile The K. . Die & Specialty ‘Co, 2018 Elm St. Cincinnati, Ohio, Dept. C. AMERICAN MADE TOYS AND NOVELTIES OrrOKTONITY to start Manufacturing Metal Toys and Novelties. No experience necessary. Enormot': demand exceeds supply. We furnish, at cost, casting- forms for production and buy entire output, also place yearly contract orders. Casting forms made to order. Catalog, advice and information free. Metal Cast a Co., 1696 Boston Roid, New York. ADVERTISER: Ask to-day for 2 copy of the “Quick-Action Advertising Rate Folder.” It cont:ins some really important facts which will prove interestins and valuable to you. It also tells ‘“‘How You Can Use Popular Science Monthly Profitably.”” You'd like to know, wouldn’t you? Address your inquiry to: Man: ager. Classified Advertising, Popular Science Monthly, 250 Fourth Ave., New York. More Money Making Opportunities on pages 8 to 26

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eee wes wee OIF RD! = See a a Do You Know~ how to give a trousseau tea? how to order in a res- taurant? tow to plan a formal wedding? how to adapt yourself to every environment? how to be socially pop- ular? how to be at ease in a ballroom? how to overcome tim- idity ? how to call on a young woman? . how to propose mar- rage? how to cultivate an in- teresting speaking voice? how to dress for social Occasions? how to entertain in the latest approved fash- ton? POPULAR SCIENCE MONTHLY a ETIQUE! j (& The Old Maid Has Vanished! “The New Book of Etiquette’ does not recognize any of the old standards, the outworn tradi- tions. Conditions of life have changed, and this 1925 book of etiquette is written for 1925 con- ditions. The old maid, for in- stance. Does she still exist? What has happened to her? Where is she now? What is she doing? How does the new eti- quette recognize her? Need a Tired Man Be Polite? “The New Book of Etiquette” refuses to accept the stilted for- malities of another age than our own. It introduces a fine sim- plicity that cannot fail to appeal to the intelligent person who has tired of the stiff, formal, artificial manners that ordinary books portray. The new etiquette, for instance, generously forgives the tired, elderly man who remains seated in the crowded subway while raucous-voiced girls swing from the straps in front of him. —and Slang Though it has been condemned by almost every writer on etiquette, slang is accepted by “The New Book of Etiquette’ which says, “Slang is a characteristic phase of the American language. It can be colourful and expressive without being coarse, and since it adds a typical verve and piquance to our talk, there is no reason why it should be condemned.” Your Copy Is Ready! A pleasure and surprise awaits youl ‘The new Book of Etiquette” will justify your greatest expecta- tions. Just the book of etiquette you have always wanted! Send off the coupon—TODAY. & New—-Unusual tively Different A sane, sensible book of etiquette at last! By the same author whose famous ‘‘Book of Etiquette’’ has sold more than a half-million copies. old customs and traditions, but upon commonsense. Here is an author who dares to be different, who dares to step out of the beaten track and write an etiquette book intended— not for the so-called ‘four-Hundred,” not for the man with a butler and a valet, the woman with a twenty-room house and a staff of servants—but for the average man and woman who like occasionally to attend a social function and feel entirely poised and at ease. For such people, ‘‘The New Book of Etiquette’ is valuable and important. It is new not only in the sense of being the latest, the most complete and the most up-to-date book of its kind—but it is based upon an entirely new philos- ophy of manners, created to fill a new need in American life. It is unquestion- ably the soundest, most sensible and most helpful book on etiquette ever written. So daring in its tearing down of old, outworn traditions that you will be amazed and delighted. Included in “The New Book of Etiquette” are letters received by the author from all over the world — school teachers, bank presidents, stenog- raphers, senators, day laborers, wives of college ERE is an entirely new kind of etiquette book, based not upon NELSON DOUBLEDAY, Inc., Dept. 2510 Garden City, New York . ” I want to see this attractive, illustrated, first edition of ‘The New Book of Etiquette, by Lillian Eichler. You may send it to me, complete in the twe volum the postnen only $1.93 plus few cents delivery ch narily s at I ell for $3.50). It is clearly understood t of Etiquette’’ for 5 days, sead and examine it an‘ that time if I like and having my money refunded. final. (5) Re SR eR Re el ce eee eee Check this square if you want these books with the beautiful full-leathe $2.44 cash with order. Leather binding outside $3.44 cash with order.) at $2.98 with same return privilege. (Orders outside the U. 8. are payable eee San Ne LE SUR RE ER > : a a 3 a a es, arges for this set (which would ordi- am entitled to keep *“The New Boo sedge it for myself, returning it within professors. A diplomat from India wrote to ask an important question, and the same mail brought a letter from an American living in Panama. The hun- dreds of questions and actual letters, and the author’s answers, are alone worth many times the price of the book. They give you information contained in no other book, information you could not obtain in any other way. “The New Book of Etiquette” SPECIAL INTRODUCTORY OFFER This is the kind of etiquette book that is really useful and important, crowded with subjects of daily personal interest, based not upon old rules and regulations but upon new conditions of life. It has been in preparation ever since the original “Book of Etiquette” appeared, and its extraordinary contents have been inspired by the contact the author has had with thousands of readers who con- fided in her their special little problems. You must have a copy. Everyone will soon be discussing it. Let us send you “The New Book of Etiquette” in the beautiful, illustrated, first edition—pay the postman only $1.98 (plus few cents delivery charges)—and if you aren’t de- lighted with it, return it to us and the examination will have cost you nothing. This coupon will bring it to you. Read it and send it off NOW. Nelson Double- gay, Inc., Dept. 2510, Garden City, New ork, and I will give y judgment in this matter is to be 1 State-..- 1 | t . ee es eS NE GD GRP ES ee ene a ee

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YREER | COLLEGE My Shop-Training Method Has Equipped 47,781 MEN To Earn from $35 Per Week to $20,000 Per Year In the Auto Business 781 men trained in my big Automobile shops, 30,245 are now in business for themselves. these have tire repair shops, some operate battery stations, others own and operate garages, service ‘Stations, or sales agencies. All are independent, and earning more money than they had ever earned before taking the Greer In 8 weeks my shop training prepares you to earn $35 to $100 per week, and more as you progress. same future is yours if you will take it. Here is my special offer. Free Tools—Free Radio Course When you enroll I furnish you, free, a special kit of tools— For a limited time I will also give you a free RADIO COURSE in connection with your regular auto- mobile subjects. Some of I get you an earn-while-you-learn Good-pay Get com- Auto Repair Section of The Big Greer Shops. 4 ie we isis | i y w This magnificent new seven story building is filled with repair shops and modern shop equip- ment entirely devoted to training Greer students. Get This FREE BOOK The Auto /, President This request brings you my entire proposition and 66 large pages of Tha eng ST ee Auto training information. Mail the coupon to ¢ 2024S. Wabash me T Pf Ave., Dept. 2402, y Chicago, II. ¢ Fs Please send me FREE _ BOOK “How to Succeed in the Automobile and Tractor Business,” Ta and special training offer. This request does not obligate me in any way. of Automotive Engineering, af wee de 2024 S. Wabash Ave., Dept. 2402 ry ae CHICAGO, ILL. E : Tee Cate eee ; Money Making Opportunities ADVERTISING ADVERTISE in 24 ee aa dailies, 24 woras, $15.00. Helpful Guide listing 1000 publications, 4c stamps. Wade Company, Baltimore Bldg., Chicago. 38 WORDS in 80 Country Town Mowspapers, $3.40. Shaw, 221 A. Northeast, Washington, D. ADVERTISING rates for eageaines and weexlies —_- a A. Lutz, Apartment 241, York. Penn- sylvan 24 WORDS combine list of 70 Sunday and weekly ~~ ipa 6.00. AdMeyer, 4112 P. Hartford, St. ouis. ONE Inch in 136 N. Y. Country Weeklies $15 one cut needed. Long Island. MR. ADVERTISER: Ask to-day for ,2 CODY of the “Quick-Action Advertising Rate Folder.” It containg some really important facts which will prove intere: “sting and valuable to you. It also tells “‘How You Can Use Popular Science ss Profitably.’’ You'd like to know, wouldn’t you? Manager, Classified Advertising, Popular Science Monthly, 250 ‘Fourth Ave., New York. ADVERTISING in all magazines and newspapers at publishers’ lowest rates. Sales letters, booklets, folders, planned, written, illustrated. Taylor's Advertising Ser- vice, Dept. A, Freeport, Illinois. FREE Copy Popular Fun Magazine, to ad Fin-Ko, 944-P Clark, Toledo, O. ver tines a A REN em PRINTING, ENGRAVING AND MULTIGRAPHING Sa MU TUNPLOS ATR TOTTI WS PAT STITT SWART meer 1,000 20 LB. Bond Letterheads, $4.50; 5,000, $16.00: 10,000, $26.00. Other sam By reasonable. Get our prices. Few samples Free. A. H. Kraus, Kraus Bldg., Milwaukee. Wis. pi nn BETTER Printing for a Money. Write us about your printing needs, and you_will save money. Ernest Fantus Company, 525 South. Dearborn Street, Chicago, EMBOSSED business, personal stationery. Samples, stamp. Daniels P. Company, Pittston, Pennsylvania. 100 EACH, Letterheads a. a $1.00. Cul- pepper Press, "Box 85, Faith, TRADE-MARKS, weet pe my illustrations for advertising. Letters, f Quick s) The Messenger, Smithtown ‘Brae olders, booklets, written. “om. fair 3 — Taylor's Advertising Service, Dept. B, Freeport, [lin BSW OHET TERY ees TEE Bond 8% x 11, 500, $2.65 cash. Other printing. 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Approval, MAIL ORDER BUSINESS NEW Mail Order Plans, Ideas and Suggestions. In “Business Progress’ Magazine Each Month. Sample Copy 10c. 734 Cherry, Kansas City, Mo. $50 a week, evenings. I made it. Mail order business; booklet for stamp tells how. Sample and plan 25c. Free, 12 articles worth $3. Alps Scott, Cohoes, New York. ADVERTISE by mail .~ keep business growing. Let me tell you more. H. J. Reeney, Room 17, Columbia Bldg.. Padueah, Ky. LETTER SPECIALISTS 20 SUCCESSFUL Collection Letters $1. Win, 405 Gotham Bank Bldg., New York, N. Y. THEY have simply got to buy when Prudence sales creators prepare just the kind of selling copy for your sales letters and direct mail campaigns, selling copy ‘that gets your prospects and orders. Send for proof of what we can do for you, and your free copies of Dealing W ith Human Nature’ Profitably and Seles Letters Profitable Business Builders. Valuable suggestions for increasiDs sales will be found in them. 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— oras, 3, 4c £0. eens 53.40, a exlies Penn- eekly » St. —— Only anch, ee Mf the FT HE drawing reproduced above was made by a student of the In- ternational Correspondence Schools. It is just one of many hundreds of drawings that our students make every year and shows what any man can accomplish through the I. C. S. Courses in Drafting. This drawing is not only accurate in construction and POPULAR SCIENCE MONTHLY We can teach you to ma drawings like this c? i Pine Tap # Deco zi chanical, structural and architectural drawings. The Drafting Courses of the Inter- national Correspondence Schools are the most practical drafting courses offered to-day. They start at the beginning and lead you forward by easy, understandable steps until you can make the most complicated drawings. It makes well executed, but the shading, the dimen- sion figures and the lettering all show the skillful handling of de- tails so characteristic of the work of first- class draftsmen. Sample no difference if you have never seen a drawing instrument. If you can write, we can teach you to draw. How to become a draftsman It is easier than it was | Snes aaa York.” And this student had never seena bow-pen afew months before! What we did for this student, we can do for you. It is a mistaken idea that a man must have a talent for draw- a Vin, 405 — profitable field. mail the coupon vertising Write for this FREE BOOKLET It tells all about the courses in Drafting offered by the Inter- national Correspondence Schools, gives the names and photographs of successful students and tells how you, too, can get a good po- sition in this interesting and you this booklet, free. a few years ago. For- merly you had to start as blue-print boy, at small pay, and the best you could hopefor after a year or so was to be promoted to the work of tracer. Then in an- other year or two you Just mark and and we’ll send ing in order to succeed as a draftsman. Any student who will study as we direct can learn quickly to make neat, accurate me- az folders. Taylor, —— ities would be advanced to making detail drawings of compara- tively unimportant parts and could call yourself a junior draftsman. e ENGINE FRAME Br Acex Bevteny Mar 2? 1924 10/17 We have more requests for trained draftsmen than for graduates of any other course Now the International Corre- spondence Schools have made it possible for you to study drawing in your own home in your spare time and thus to enter a drawing room, not at the bottom as blue-print clerk, but as draftsman, at a good salary from the start. Mail the coupon for free booklet which explains everything. “INTERNATIONAL CORRESPONDENCE SCHOOLS Box 7616-D, Scranton, Penna. Without cost or obligation on my part, please tell me how I can qualify for the position or in the subject before which I have marked an X: BUSINESS TRAINING COURSES Business Management H Salesmanship Industrial Management Advertising Personnel Organization Better Letters Traffic Management Show Card Lettering | [] Business Law Stenography and Typing [jBanking and Banking Law Lj Business English [} Accountancy (including C.P.A,) (J Civil Service [j Nicholson Cost Accounting Railway Mail Clerk [ } Bookkeeping Common School Subjects Private Secreta High School Subjects Spanish French Llustrating TECHNICAL AND INDUSTRIAL COURSES OD Electrical Engineering Architect Electric Lighting Mechanical Engineer () Mechanical Draftsman Machine Shop Practice Railroad Positions Gas Engine Operating Civil Engineer Surveying and Mapping Metallurgy Oj Mining Steam Engineering 0) Radio Architects’ Blue Prints Contractor and Builder Architectural Draftsman Concrete Builder Structural Engineer Chemistry () Pharmacy Automobile Work Airplane Engines Agrieulture and Poultry Mathematics Street 3-6°24 BGATOBB 0.000. cccerccccorccccccccccecscccesscoccceccsacs oesvscoscnesconcseecesonesosones CDeCUPAthOR..cccceccccccccrccccrscccesecccesccccese - cone Persons residing in Canada should send this coupon to the International Correspondence Schools Canadian, Limited, Montreal, Canada

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Free—1924 Reference Atlas You may have the 1924 edition of the ‘‘New Reference Atlas of the World”’ without a penny of cost. It contains 148 pages with 96 pages of maps, beautifully printed in colors, including all recent changes in the countries of the world, new census figures, parcel post guide. Bound handsomely; size 95 x 121% inches. This splendid Atlas is included free in our special offer to new sub- scribers for WEBSTER’S NEW INTERNATIONAL DICTIONARY The Merriam Webster The ‘“‘supreme authority’? —a complete reference library in dictionary form—one big, convenient volume, the type matter of which is equivalent to a 15-volume encyclopedia. Thousands of new words that have only recently come into use; 407,000 vocabu- lary terms; a biographical section giving information about 12,000 famous men and women; 32,000 geographical sub- jects; over 6,000 illustrations; answers all your questions about words, people, places and things. On approved orders this valuable work will be Delivered for $1.00 and the balance of the price may be paid in easy monthly payments. The Hon. Calvin Coolidge wrote: ““Webster’s New International Dictionary has been the official reference and|authority in my office in Washington during my service POPULAR SCIENCE MONTHLY The Magic of Words is working miracles of achievement every day. It enables one man to con- vince his business associ- ates, another to win a case in court, another to play on the emotions of a great audience. Words rightly used are the open sesame to cultured society, to busi- ness success, to political power. You can use the magic of words in attaining your great ambition. You need only develop your mastery of expression by using the language power so fully offered to you in WEBSTER’S NEW INTERNATIONAL DICTIONARY. Yours Free on Request The Magic of Words” You may have this inter- esting, illustrated booklet free. You will enjoy its illuminating story and profit by its practical sug- gestions. It offers also full information about the high- est authority of the English speaking world. This Coupon Brings Your Copy, FREE as Vice President. It is a standard work £"~"">~77777777T7 and most useful to me.’? Send coupon ! &*% grisea as for-the free booklet, "The Magic of ¢ Please send me, without cost Words,’’ and see why it ! bcckles "The Magic of Words” and fall infos ‘ will be most useful to you. 1 TIN yourspecial Frerlasoffen (Pop. Sc, 70-24) G. & C. MERRIAM COMPANY} Xame Springfield Mass. : Bienet = = City and State rc we wewowe ww ww oe www oe - ee ow J Money Making Opportunities PHOTOGRAPHY AND SUPPLIES ————— HAVE you a camera? Write for free sample of our b magazine, showing how to make better pictures a money. American Photography, Boston. 17, Massachusettz. MR. ADVERTISER: Ask to-day for a copy of the “Quick-Action Advertising Rate Folder.” It containg some really important facts which will prove interest and valuable to you. It also tells ‘‘How You Can Use Popular Science Monthly Profitably.”” You'd like to know wouldn't you? Address your inquiry to:—Manager’ Classified Advertising, Popular Science Monthly 256 Fourth Avenue, New York. “= CLEAR, bright prints that will never fade; 3c each for vestpocket size; brownie No. 2 and No. 2A, 4c eae larger sizes, 5c each. 8x10 enlargement 55c from any idak film. We develop any roll film for 10c; film packs 25c, mailed back same day. Satisfaction guaranteed Leon Lambert, 670-E South Volutsia, Wichita, Kansas,” DEVELOP and print your own films. Complete for- mulas, 60c (no stamps). Results guaranteed. Studio “L,”’ Owego, N. Y. 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Mention instrument, Virtuoso Music School, Concord 36, Mass. NOVELTIES ARMADILLO Baskets, ge 9 novelty; samples par- cel post piid, plain baskets, $2.50; silk trimmed, $3.50 each; satisfaction guaranteed or money back. Charles Apelt, Comfort, Texas. OPTICAL GOODS ARTIFICIAL eyes, $3. Booklet free. Denver Optic 508 Barclay, Denver, Colorado. MR. ADVERTISER: Ask to-day for a copy of the “Quick-Action Advertising Rate Folder.’ It contains some really important facts which will prove interesting and valuable to you. It also tells “How You Can Use Popular Science Monthly Profitably.’’ You'd like to know, wouldn't you? Manager, Classified Advertising, Popular Science Monthly, 250 Fourth Ave., New York. WATCHES & JEWELRY 21 JEWEL Railroad Watch, $9.85 cash, $12.00 puy- ments. 16 Jewel White Gold Ladies’ Wrist Watch, 10% linge octagon, $9.85 cash, $12.00 payments. New high — watches. Davis & Davis, 614 Jefferson, Greenfield, 0. Address MISCELLANEOUS FORMS to cast Tin Soldiers, Indians, Marines, Trap- pers, Animals. Send 5c for catalogue. Henry Schiercke, 1034 72nd St., Brooklyn, N. Y. PASTE Glove. A notable scientific discovery, protects your hands perfectly from oil, paint, grease, stains, dirt. Pleasant to use. 50c large tube. Peterson-Kintner Co., Farmers Bank Bldg., Pittsburgh, Pa. MAGIC TRICKS 375 MAGIC Tricks, 40c. Catalogue 10c. Chelsea, 38214 East 144th, New York. TRICKS, jokes, magical apparatus, sensational escapes. Illustrated catalog, 10c. Oaks Magical Co., Dept. 550, Oshkosh, Wis. CHALK TALKS LAUGH producing program, $1.00. Circulars free. Cartoonist Balda, Oshkosh, Wisconsin. FOR MEN AND WOMEN DETECTIVES—Work home or travel. unnecessary. Write George Wagner, former Govern- ment Detective, 1968P, Broadway, New York. GENUINE Indian baskets, blankets and wampum— wholesale. Catalogue. Gilham, Kelseyville, California, WANTED—Representatives in every factory in the United States. Popular Science Monthly, 250 Fourth Ave, New York. ALL men 45 or over must have my aid. No medicine, electricity or humbug. Rexo, Box 2402, Boston, Mass. INFORMATION ate ire COMPLETE, accurate information on any subject. $1; National Information Bureau, 1429P Milton St., Gran! Rapids, Michigan. LEGAL questions answered, guaranteed correct, $1.00. Edgar Keller, Augusta, Montana. More Money Making Opportunities on pages 6 to 26 Experience

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eS songs, ne for POPULAR SCIENCE MONTHLY ‘90 Drafting Course FREE There is such an urgent demand for practical, trained Draftsmen that I am making this special offer in order to enable deserving, ambitious and bright men to get into this line of work. I will teach youto becomea Draftsman an Designer until you are Drawing a salary of $250.00 a month. You need not pay me for my personal instruction or for the com- plete set of instruments. But you must take advantage of this special offeratonce. $300 a Month Salary $450 0n theSideat Home! Chief Draftsman Dobe I Guarantee To Train You Until You Are Placed in a Position Paying up to $250 and $300 a Month Write and I'll tell you how I make you a first- class, big-money-earning draftsman in a very few months! I do this by a method no other man nor institution can imitate. I give you personal training at home by mail until you are actually placed in a position paying up to $250 and $300 a month. Six thousand drafts- men are wanted every month. Free Book Send Coupon Today RF No matter what plans you have for the future. Get this great book—‘‘Successful Draftsmanship.” Find out about the simply marvelous opportunities ahead now. How the world needs draftsmen, engineers, architects and builders. What great salaries and pos- sibilities there are! Send coupon for free book today. . Chief Draftsman, Engineers Equipment Co. 1951 Lawrence Ave. Div. 13-67 Chicago, Ill, That’s the kind of money my drafting students make. Read what this one says: “As a beginner Iam ong fine. Am earning a salary of $300 per month, besides last two months, drawing plans for private parties. The bractical drafting training you gave me by mail put me where Iam in less than six month’s study. Thank you for all your personal interest and helb you gave me cane f made over $450 at home the ar. (Signed) J. B. (Name and address upon request) il Biba TT SN. 9711) And more—I give you a whole set of drafting tools the minute you become my student. You get every tool you need A magnificent set of instruments which will build your success in draftsmanship, Chief Draftsman, Engineers Equipment Co. 1951 Lawrence Ave. Div 13-67 Chicago, Ill. Without any obligation whatsoever, please mail your book, Successful Draftsmanship’”’, and full particulars of your liberal ‘“‘Personal Instruction” offer to few students. ns oe cebbesannedesedsaeds ible sseavereenne POst Office..ovecccccccccccecscerss

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12 POPULAR SCIENCE MONTHLY Money Making Opportunities ORCHAKDS AND FARM LANDS PECAN-ORANGE Groves “on the “Gul a 7 monthly. Guaranteed care. Soop produce $500.00 yeas > Suburban Orchards, Dept. < Biloxi Mississippi. —\IR. ADVERTISER: Ask to-day eo “Quick-Action Advertising Rate Folder, PY of the some really important facts which = y Contains and Ln. Ay to you. It also tells “How You Popular Science ag A profitably. know, wouldn't ie anager, Classified

Popular Science Monthly, 250 Fourth Ave. eon a, : ; ANGUAGE ‘Send the coupon and get this free Trial | “WORTD-ROMICSystem, Masterhey to al lee Tanga . r Primeis, $1.94 each language; Chinese, French, §) os; Lesson in Drafting prepared by the ee 30c. g pictionaries gram: — ° . anguages uages, it 4 v Chicago Tech. Experts. While other So schools ask you to enroll and pay fees at | ~ST-TUT-I-I-TERING and stammering cured 7 He tae ‘ home. Instructive booklet free. hg 1 McDonnell, 59 once, Chicago Tech. sends this free lesson | Potomac Bank Building, Washington, D 3 which will show you how well qualified camer a

you are to take up this paying profession. | 501 Rockwood, Dallas, Texas, P* “Ne4P: Bulldog, I It also shows the Chicago Tech. method of | oorang Airedale watch dogs, ‘automobile dogs" clu training men by mail. Find out all about | retrievers. "Also Ble Game Hounds, Coonkeng 204 | this before you pay a penny or decide | Airedale puppies. Hounds and t Merguenbred Hound and 3 about enrolling. Mail the coupon now. | tuted deseriptive catalog free. Oorang™ Kenna hi 208—La Rue, Ohio. th:

Catsiunen ” Wackeahen teen. se ck, fe COD. on FOR SALE —— v ROCKS and minerals for sale—hundreds of varieties— price list free. P. Zodac, 157 Wells St., Peekskill, N. y, PATENTS FOR SALE

———— — FOR a oe bd oo 1433832, on wheels, » s. Construction easy. Alfred 938. Geers a Street, Trenton, N. J. Lyneh, expert trainin b m MR. ADVERTISER: Ask to-day for a copy Get oa i bi 8 in Drafts anship and ery $25 Drawing Outfit “Quick-Action Advertising Rate Folder.” i nae the yoursel in the big pay class. Don’ t stay in a sma some really important tacts which will prove interesting job when you can master Drafting in your spare time by the Included and valuable to you. It also tells ‘‘How You Can Use Chicago Tech. Method. Not enough expert Draftsmen to fill Popular Science Monthly Profitably.”’ You'd like to know. tra the high salaried positions open now. You don’t need special, peta PF a A Ey Popular Lo reliminary education to master Drafting. The Chicago Tech. SOS ERSTERTTRN LILTRIEE GICAL RTT fethod makes every step so easily understood that any in- te Sie a ICAL SERVICE lige an can master the subject. Tice list for chem ts and ex riment telligent man can maste 1e subject George Ott, (215 Chestnut, Meeting, Pa. pe ers, * . J e YOUR chemical problem solved and working proc Train in Spare Time at Home furnished for five dollars. Write me. W. “sfeaman pe Enrolled at Chicago Tech. you are instructed by Hichards, Consulting Chemist, Box 2402, Boston, ‘Mam mi practical enginee rs—not by mere theorists. These Rare, Dependable Fo eM aires ha men have been “‘through the mill.’” They know just what prob- detailed —— directions, ‘‘inside’’ commercial in- ha lems you will have to solve in actual practice and they show you formation. n't buy till I've sent you my Valuable rp how to master them. No time wasted on unnecessary studies. poner 2 Lists _ eeenaeeen, — _™ Dr. Lis- I You graduate early and can stand beside men of long experience. f com ee ems ampa, Florida. You get this training at a low cost and on easy terms at the Students enrolled with Chicago Tech. for FORMULA a College in Chicago or by mail at home. For those who come to home study in Drafting receive this com- BESTALL Chemical Wood Stone—For public building, 1s Chicago many opportunities are open to earn expenses while plete Drawing Outfit (retail price $25) kitchen and bath room flooring. Can be molded into attending day or evening classes at the college. Here is the with no extra charge or credit on fees if | Mmumerable souvenirs and ornamental novelties. Com. - chance to satisfy your ambition, to step quickly into a bigger they have outfits. A regular full size out- Pracim Building, New Castle, Indiana. Deny saa income follow a profession, to win independence. Send the fit—same as used by practical draftsmen : . . to smcome, to 50 = . 4 enukaenie FORMULAS for more than 400 saleable articles in coupon now. and eng ° our practical book for 50c, postpaid. Pentland Service, ye 1 Thames Ave., Norwalk, Conn. e e ° in; SEND COUPON (Chicago Tech. Men in Big Demand | 55: (nitiss aoe. all three $280. Rogers Hook Cr 839 Oak, Cincinnati.

“ : : + en Mail the coupon and get the Free Trial Railroads, manufacturers, architects, contractors, BALDNESS Cured. a aly an ns Lesson—also catalogs and full informa- electrical works—big industries everywhere—are | hair. $3. The Process Co., Denver, Colo. | tion about the Chicago Tech. Method always looking for expert Draftsmen. Chicago Tech. graduates MR. SDVERTISER: Ask to-day for a copy of the tr of teaching Drafting by mail. No cost ful n-because they have the “‘Quick-Action Advertising Rate Folder.” It contains : - . step into the ranks of successful me ecau ar to you—no promise or obligation, Send practical knowledge which is wanted. E. A. McGurney was ot kaas cee” gy A “% po today. drawing $35 a week. Trained the Chicago Tech, way and is Popular Science Monthly Profitably.” Berd like to know. i (a ce ee ee ee ee making $4500 a year. The same training increased Rex Cary’s wouldn't you? Manager, Classified Advertising, Popular C CHICAGO TECHNICAL COLLEGE salary 300% and put O. L. Rosin in a successful business of his Science Monthly, 250 Fourth Ave., New York. m Dept. 1031, Chicago Tech. Building, 1 own. Hundreds of others re- OH Boys Make and Sell Automobile Enamel. Makes $a 118 East 26th St., Chicago, Ill. | port similar results. “wae aay one mate oor Ee a aw. Apply cet = te have the same chance. nat i ildi 2 eese Without cost or obligation on me please I near ts training to make To Men in Building Trades ormula and working plans $1.00. MITCHELL-Ames in send Free Trial Lesson in Drafting and other ] vorth more Send for Catalog = B”’ and Co., Effingham, Illinois. instructive matter about opportunities open your services wo our Free Book How to TOR INVE s <i to me in this profession. I = iggthicose* act ‘gh pees ge ove ~ CASHING in—If you have a practic.l, useful in- ro . . - : : = an aes "AS — Print or write name and address plainly. | ea ogg ae —. a at ee agg herent ae crdechcak vention to sell (patented or pending) write us today. d | , or traini by mail at about the higher branches American Patents Corporation, arrister Building ‘ Ny ES Se Se ne Re eee yous ted PALES *f airard of your trade—Plan Reading, Washington, D. C. [eee Estimating, Superintending. INVENTIONS technically developed. Patent and b to pay. Working drawings prepared. Wettstein, Engineer, 150 Address___-------.------------------ ] Nassau St., New Yor bi UNPATENTED Ideas Can Sold. I tell you how | . . th ES SEER SS See evan ean Ce eee emeee eR eene es and help you make the sale. Free particulars (Copy- se ; Chicago Technical College ahs” Ratt W. "HC Gitano Vener bolder " Diss mckchektinen news Gilde nike ancl | Dept. 1031, Chicago Tech. Bldg., 118 East 26th St., Chicago, Ill. ashington, D. C.

MODELS, Tools and Gears. Send sketch for estimate. A. Schmidt, 400 Canal St., New York. INVENTORS’ Educator: 900 Mechanical Moverrents, 50 Perpetual Motions. How to procure and sell p: tents. Mechanical Movements greatly assist Inventors, suggest new ideas. Explains how to select an attorney and avoid Patent Sharks. Price $1.50. Postage free. Albert E. a Dieterich, 681 Ouray Building, Washington, D. C. PATENTS—Write for Guide Books and “Record of Invention Blank.’’ Send model or sketch of your inven- tion for our free Examination and Instructions. See advertisement on page 145. Victor J. Evans & Co, 156 Ninth, Washington, D. C. TO SELL your patent, write me; experienced handling immediate action. rome ody Arthur §. Billings, Suite 401 C ‘1600to'2300 Year /mnginenue, (egg oe | Cutting, Campbell, Calif. Men—Boys 18 Up egitim INVENTIONS Commercialized, Patented or un s

c or aoe Send me ot charge, (1) = patented. Write Adam Fisher Mfg. Co., 183, St. Lome, Me M mmedi , Rai way al er xamination questions; MR. ADVERTISER: Ask to-day for a copy 0 ail oupon j lately s (2) Send List of Ss. eT tit ob- “Quick- Action Advertising Rate Folder Bn [ ai : illust ook, “How some really important facts which will prov: ce I Foca Gonna ie.” and valuable 10,70U., tt slg ate Ht ie Io AD ‘opular Science Monthly Profita : - re , wouldn’ "t you? Manager, Classified Advertising, Pop’ Common education sufficient 7) vom. Science Monthly, 250 Fourth Ave., New York.

/ | More Money Making Opportunities Travel—See Your Country 7 Be eT OT Ea eC ee ee pesto ih aie ie aioe eee on Pages 6 to 26 N

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ively grows opy of the It contains ng. Popular a Makes car with a liar bottle. [ELL-Ames Patent and gineer, 150 eee se ‘ll you how lars (Copy- r Building, a or estimate. oe Mover ents, sell p: tents. ors, suggest y and avoid Albert E. D. C. ———— “Record of your inven- ctions. See ans & Co. ed handling s, Suite 401 $1. Cooper ae ted un- it. Louis, Mo. copy of the It contains e interesting ou Can Use like to know, ing, Pop et unittes The Only Way Out of a Pit— —UP! T was Jack London—penniless and with only a scanty education—who uttered those words— —‘‘The only way out of a pit is UP!’’ That one clear challenge, flashing across his mind with the force of inspiration, gave the impulse to work and study which set him on his way to a brilliantly successful career. The One Great Test — COURAGE! It has been said that the great difference between one man and another is in the amount of COURAGE he possesses. Not PHYSICAL courage, of course, but the courage to turn the searchlight on one’s MENTAL equipment, to recognize the training which one lacks, and to do as Jack London did—climb out of the ‘‘ pit.’ Right now, in your own office, there are probably dozens of men who are performing the same old routine tasks they have been performing for years—tasks which literally millions of men could do equally well; yet hardly a man in the lot but thinks he is having a “‘mighty hard time’’ and | that “‘luck never seems to break his way.’ But how CAN it break his way—when he is obviously not PREPARED? How futile, for example, to expect an employer in need of an expert accountant to appoint a man—at five or six thousand a year—who knows nothing beyond the keep- ing of a set of books. —Or to expect the head of the firm to entrust his transportation problems to a man who has got all his knowledge about traffic management from the shipping room and the loading platform! —Or to expect ANY reputable business house to choose, say, as district manager a man who has no conception whatever of salesmanship—to advance to the superin- tendent’s desk a foreman who knows noth- ing about industrial management efficiency —to entrust a direct-by-mail campaign toa routine correspondent—or to appoint a ‘‘one- department man’’ as general manager. . it may be RESTFUL to stand at the bottom of the pit and to gaze at the stars— but the SHREWD thing to do is to seize the rope of SPECIALIZED TRAINING —and to pull oneself OUT! LA SALLE EXTENSION UNIVERSITY POPULAR SCIENCE MONTHLY The Kind of Experience That COUNTS —And EASIER, too, by far, than one might suppose—this climbing to a h.gher place by the aid of specialized training. For within the last two decades a method of business training has been evolved which marks an advance beyond the earlier cor- respondence-school idea as outstanding as the advance of radio beyond the original Marconi ‘‘wireless.’ Under this modern method —distinctive with LaSalle Extension University — every portion of the work is directed toward the rapid nee of ORGANIZED EX- PERIENCE, Step -- step, the member is shown the PRINCIPLES which govern the various business situations he must face in that bigger place—and step by step he fixes those principles firmly in his mind through the solving of ACTUAL BUSINESS PROBLEMS. A dozen times a man might READ how to do a thing—how to swim, for example— and STILL be unable to do it! But let him grasp the PRINCIPLES that govern an undertaking—and let him ut them into successful PRACTICE—and e has acquired the greatest asset a business man can possess—thoroughly practical EXPERIENCE, A Club That Everyone Likes to Join Hundreds— yes, thousands of letters in the files of LaSalle Extension University bear out the scien- tific soundness of the LaSalle Problem Method. The members of LaSalle, for example, have a club they call the “100% Club, *?to which no man is — until he has increased his salary at least one hundred per cent. Not a month goes by but what scores of names are added to its rolls. Indeed, if we liked, we could fill this page—in close-set newsprint type—with the names of just a small_ proportion of the_men who have actually DO D and TRIPLED their incomes through the Problem Mcthod. These men, you will say, are men of unusual determination and persistence — Absolutely true. — But also true Je no one KNOWS what he can do — TRIE NY a in earnest to advance will find en, aig in the fact_that the AVERAGE salary-increase reportcd by ne trained men is EIGHTY-NINE PER CENT i3 Ask Yourself if You Can Qualify— Then ACT! There is a certa: 1 class of men who seem con- tent in a low-pay jcb. There is still another class in whom the phrase can’t” is so deep-rooted that they seem afraid to grasp the fairest opportunity. either of these types are sought by LaSalle— nor would they profit greatly by its training. There are countless other men, however, who appreciate what specialized training MEANS—who realize the tremendous HELP it offers—and who are not afraid to take their chance against the en- tire field of competition. To men of this latter sort LaSalle Extension University has much to offer—both for mental growth and for increased earning power. If you are in earnest when you say that you wish to get ahead, you will take your pen or pencil NOW —and check’ the training that appeals to you. The coupon, signed and mailed. will bring you information that will prove worth while. — tr ere is, of course, no obligation, “ The e Largest Business Training Institution in the fe ae ald lee World LASALLE EXTENSION UNIVERSITY Dept. 1083-R - Chicago, Illinois iN Please send me catalog and full information regarding the course and service I have marked with an X below. Also a copy of your book, “Ten Years’ ns E> in ate ” all without obligation to me. Business Management: Trainin for Traffic M oreign and Official M Lege rn Sales and Departuental Executive positi ons [nduotrial Manag: nme | for positions in Works Man- 5 ee Rate agemen' ction Control, Industrial ement Efficiency: Business Eng- lish: ee Domestic: Treming f Tram Torn Position as Rail- for Business road or industrial ight Expert, Fre: Ngineering, etc. espond- ents and Training for —_ Modern Salesmanship: P 1 and Emp! tM: ti Railway Station t: Train- ‘ersonnel an ploymen anage- U soach bor Trainer. ie hime tae int for p Position "of Station a Accountant, poor Bonen ” ed esi. noe Worers Manufacturer’s Agent, Solicitor, and all Cashier and Agent, Division Agent, etc. ens “oo “ t “ge on d Co ercial Spanish : Trai for tionsin retail, who esale, or specialty s ine ; anager, Employmen anager, an Cc] mm $ raining peck B and Finance: Training for positions relating to Employee Service. — as Ba mr Correspondent with Higher Accountancy: Training for posi- Financial AF — ey in Banks and Modern Business Correspondence panish -speaking countries. tion as Aaditor, Ceespteoller.- Certified Public Accountant, Cost Accountant, etc. Law: Training for Bar; LL. B. Degree. Commercial Law: Reading, Reference and Consultation Service for ss Men, = Practice: Training fcr wy Kw g~ ee ee og the foo to. ae he Ministers, Salesmen, Fraternal Leaders, Politicians, Clubmen, ete. C. P. A. Coaching for Advanced Ac- countants. ModernForemanshipand Production Methods: Training for positions in Shop Promotion Manager, Mail Sales Man- Management, such as that of Superin- ager, Secretary, etc. tendent, General Foreman, Foreman, Ex; Bookkeeping: Training for Sub-Foreman, ete. posi.ion as Head kkeeper. Name Present Position Address bs an

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How to speak and write Masterly English Thousands of people make little mistakes in their every- day English and don’t know it. As a result of thou- sands of tests, Sherwin Cody found that the average erson is only 61% efficient in the vital points of English. n a five-minute conversz ation, or in an average one- page letter, from five to fifty errors will appear. It is sur- rising how many experienced stenographers fail in spell- ~ such common words as ‘‘business,”’ ‘abbreviate,’ etc. It is astonishing how many business men say ‘between ‘ou and yg instead of * ‘between you and me,” and use ‘who” for ‘‘whom’"’, and mispronounce the simplest words. Few persons know whether to use one or two **m's" or “‘r’s,"’ whether to spell words with ‘ei,"" and when to use commas in order to make their meaning absolutely clear. A REMARKABLE INVENTION Mr. Cody has specialized in English for the past twenty years. But instead of going along in the old way he has applied scientific principles to teaching the correct use of our language. He made tens of thousands of tests of his various devices before inventing his present method. In all his tests he found that the trouble with old methods is that points learned do not stick in the mind. In school you were asked to remember rules and if you forgot the rules you never could tell what was right and what was wrong. For many years Mr. Cody has studied the prob- lem of creating instinctive habits of using good English. And as a result of his experience he evolved his wonderful new SELF-CORRECTING METHOD A patent was granted Mr. Cody on his unique device, and now he places it at your disposal. This invention is simple, fascinating, time- -saving, and incomparably effi- cient. You do the lesson given on any page, then you see exactly how Mr. Cody himself would correct it. You mark our errors and check them in the first blank column. ext week you try that page again, on the second un- marked sheet, correct your errors, ‘and check them in the second column. You see ata glance what you have learned and what you have failed to remember, until you have reached the 100% point in spelling, punctuation, grammar, and expression. ONLY 15 MINUTES A DAY A remarkable advantage of Mr. Cody’s course is the speed with which these habit-forming practice drills can be car- ried out. You can write the answers to fifty questions in 15 minutes and correct your work in five minutes more. You waste no time in going over the things you already know. Your efforts are automatically concentrated on the mis- takes you are in the habit of making, and, through con- stantly being shown the right way you soon acquire the correct habit in place of the incorrect habit. There are no 1ules to remember. There is no tedious copying. There is no heart-breaking drudgery. FRE E BOOK ON ENGLISH AND 15-MINUTE TEST A command of polished and effective English denotes education and culture. It wins friends and makes a fa- vorable impression upon those with whoin you come in contact. And now, in only 15 minutes a day—in your own home—you can actually check up and see yourself improve by using the 100 per cent, self-correcting method. If you are efficient in English it will give you great confidence; if you are deficient you surely want to know fit. For this reason Mr. Cody has prepared a simple 15- minute test which you can take in yourown home. The correct answers are given so you can tell at once just where you stand. Write to-day for this test—it is free. We will also gladly mail you our new free book, ‘‘How to Speak and Write Masterly English.’’ Merely mail the coupon or a postal card. SHERWIN CODY SCHOOL OF ENGLISH 1810 Searle Building Rochester, N. Y. en ee 2 FS SS A A LY A TS SHERWIN CODY SCHOOL OF ENGLISH 1810 Searle Bldg., Rochester, N. Y. Please send me your new Free Book, and Write Masterly English,’ and the

“*How to Speak 15-minute Test. i Meccano bonnes ine hcnncnebncencaeee

POPULAR SCIENCE MONTHLY ney Making Opportunities PATENT ATTOKNt YS PATENTS— Before ‘disclosing an invention the in- ventor should write for our blank form ‘‘Record of Inven- witnessed and returned to us together with model or sketch and description of the Inveation for Free Examination and Instructions. hree ks mailed tree to inventors. Our illustrated Guide Book, ‘“‘How to Obtain a Patent,” contains full inetructions regarding patents. Copies of unsolicited letters from manufacturers and others who are constantly writing us regarding the purchase or leasing of merito- tious patents sent upon request. See advertisement on page 145. Victor J. Evans & Co., 937 Ninth, Washing- ton, D. C. UNPATENTED Ideas Can Be Sold. and help you make the sale. Free particulars (Copy righted T933). Write W. T. Greene, 811 Jenifer Building, ashington, D. C “INVENTOR’S ADVISER” the valuable Patent book with 139 mechanical movements and illustrations, sent free upon request.—M. 8S. Labiner, Patent Attorney, 3 Park Row, New York. MR. ADVERTISER: Ask to-day for a copy of the “Quick-Action Advertising Rate Folder.’’ It contains some really important facts which will prove interesting and valuable to you. It also tells ‘‘How You Can Use Popular Science Monthly Profitably.”’ yew d like to know, wouldn't you? Manager, Classified a Popular Science Monthly, 250 Fourth Ave., New Yor MILLIONS spent annually for Toa Hundreds now wanted! Patent yours and profit! Write today for free books—tell how to protect yourself, how to invent, ideas wanted, how we help you sell, etc. American Industries, Inc., 501 Kresge Bldg., Washington, D. C. PATENTS, trade marks, copyrights. Prompt, per- sonal reliable service. Over 30 years’ active practice. Write for terms. Book tree. Address E. G. Siggers, Box 1, N. U. Building, Washington, D. C. ~PATENTS—My fees in installments. Advice book free. Frank Fuller, Washington, D. C. INVENTORS: Send sketch or model tor free opinion concerning patentable nature and exact cost of patent. Book, ‘‘How to Obtain a Patent,’ sent free. Tells what every inventor should know. Established twenty-eight years. Highest references. Prompt service. Reasonable 2 ae Chandlee & Chandlee, 478 Seventh, Washington,

I tell you how

THE PATENTOME. Impartial advice to Inventors and Manufacturers. Mailed on request. Anderson & Son, Patent & Trade Mark Lawyers, Established 1865, 636 F St., Washington, D. C. MR. ADVERTISER: Ask to-day for a copy of the “Quick-Action Advertising Rate Folder.”’ It contains some really important facts which will prove interesting and valuable to you. It also tells ‘‘How You Can Use Popular Science Monthly Profitably.’’ You'd like to know, wouldn’t you? Manager, Classified Advertising, Popular Science Monthly, 250 Fourth Ave., New York. PATENTS—Write for my free Guide Books ‘‘How to Obtain a Patent’’ and “Invention and Industry” and ‘Record of Invention’’ blank before disclosing inventions. Send model or sketch of your invention for instructions. Promptness assured. No charge for above information. Clarence A. O’Brien, Registered Patent Lawyer, 1845 Security Bank Building, directly across street from Patent Office, Washington, D. C. See page 143. H. F. LOWENSTEIN, Registered Patent Attorney. a ea expert. 817 McLachlen Building, Washington,

PATENTS. Booklet free. results. Promptness assured. Watson E. Coleman, Patent Lawyer, 644 G. Street, Washington, D. C. PATENTS Procured; trade marks registered—A comprehensive, experienced prompt service for the protec- tion and development of your ideas. Preliminary advice gladly furnished without charge. Booklet of information and form for disclosing idea free on request. Richard B. Owen, 44 Owen Blidg., Washington, D. C., or 2276-Z Woolworth Bldg., New York INVENTORS’ Guiue free on request; gives valuable information and advice for all who have original ideas or improvements. Frank Lederman, Registered Attorney and Engineer, 15-S Park Row, New York. ESTABLISHED 1864. Milo B. Stevens & Company, —— Attorneys (No. 830). Patents, Trade-Marks, Copyrights. Full information upon request. Moderate fees. Offices: Barrister Building, Washington; Leader Building, Cleveland; Monadnock Block, Chicago. MR. ADVERTISER: Ask to-day for a copy of the “Quick-Action Advertising Rate Folder.” It contains some really important facts which will prove interesting and valuable to you. It also tells “‘How You Can Use Popular Science Monthly Profitably.’ You'd like to know, wouldn't you? Manager, Classified Advertising, Popular Science Monthly, 250 Fourth Ave., New York. MONROE MILLER, Ouray Blidg., Washington, D. C., Patent Attorney; Mechanical, Electrical Expert. Free Blue Book gives candid advice. * HERBERT JENNER, patent attorney and mechanic: l expert, 606 F Street, Washington, D.C. I report if patent obtainable and exact cost. Senc for circular. INV ENTORS—Send for form ‘Evidence of Concep- tion’”” to be signed and witnessed. Form, fee schedule, information free. Lancaster and Allwine, Registered Patent Attorneys in United States and Canada, 232 Ouray Bldg., Washington, D. C. PATENTS for Inventions. grade work, rates reasonable to patentability. New Yo MR. STRING Ask to-day for a copy of the *‘Quick-Action Advertising Rate Folder.” It contains some really important facts which will prove interesting and valuable to you. It also tells “‘How You Can Use Popular Science Monthly Profitably.” You'd like to know, wouldn’t you? Manager, Classified ae. Popular Science Monthly, 250 Fourth Ave., New Yo INCORPORATIONS Incorporator. Charters: Guyer, 901 Orange St., Highest references. Best

Long experience, highest best references. Advice :s Wm, Ashley Kelly, 41 Park Row,

DELAWARE forms. Chas. G. Delaware. INCORPORATE Delaware. F. Lewis Mettler, Market St., Wilmington, Del. (Established 1909.) MR. ADVERTISER: Ask to-day for a copy of the “Quick-Action Advertising Rate Folder.’ It contains some really important facts which will prove interesting and valuable to you. It also tells “‘How You Can Use Popular Science Monthly Profitably.’’ You'd like to know, wouldn't you? Manager, Classified oe Popular Science Monthly, 250 Fourth Ave., New York More Money Making Opportunities on pages 6 to 26 Fees Small; Wilmington,

832

=I COLOR vey at O) oven erotiye| Commercial Drawing

| Become An This Ne.» Easy Way Thousands who never dreamed Artist

they could draw can now easily become artists. You too—without | any previous training—and no | } matter how little apparent talent 1 you have—can now easily learn Illustrating, Designing and Cartoon- ing through this amazingly casy method. You learn at home yet your work receives the personal attention and criticism of one of America’s most successful artists. Many students actually sell enough work during their training to pay for it many times over. Big Money in Commercial Art Millions of dollars are being spent this vear on advertising and story illustrations, commercial designs, and cartoons. And even more will be spent next year. Com- mercial art is a tremendous field—and a field where very big money is gladly paid anyone who can produce good art work. Adv ertisers, magazines, newspapers, print- ing houses, business concerns all need trained artists. Competent artists easily earn from $50 to far over $300 a week. And now you can easily enter this ‘ ‘world’s most fascinating, best paid business.” MAIL COUPON FOR FREE BOOK A new handsomely illustrated book has just been printed, which gives all the most up-to-date information on the thousands of wonderful opportunities in Commercial Art and shows how this startling new mcthod easily enables you to enter this field. It tells about our students—their success—what they say—actual reproductions of their work—how they made big money while studying. This attractive book will be sent without cost or obligation. Send fcr it. Mail coupon now. Washington School of Art Room 2410, -1115-15th St. N.W. Washington, D. C. WASHINGTON SCHOOL OF ART Room2410,1115-15thSt.,N.W.,Washington, D. C Please send me without cost or obligation your new book on art, ‘‘New Easy Way to Become an Artist, and details of your special offer. ENO Ciel cat wa se nis sane Meenas © es Please write plainly Mr., Mrs., or Miss. IE Soe 24.0 -p sos en Os a ROR S BORER storia a 456 6 aie ns eee <aslemataet State.....-.

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POPULAR SCIENCE MONTHLY 15 Ki. . SUULLED CARPENTERS GET THE STEADY JOBS ay med isily 10ut no lent earn o0n- Easy vork and nost ents heir NOW your job and you'll never be without one. The man that takes pride in his per- sonal skill is the man that is always in demand. The skilled carpenter’s work is the easiest be- cause he knows the practical short cuts and modern methods. His pay is higher because he does more and better work with less effort. Audel’s Carpenters’ & Builders’ Guides give you a Helping Hand into the Master Class. A complete Carpenter’s and Builder’s Course for study and ready reference. The Helping Hand Is Extended To You Carpenters everywhere are using AUDEL’S CARPENTERS’ & BUILDERS’ GUIDES as a helping hand to easier work, better work and better pay. To get this assistance for yourself you need only use the coupon below without risk. Find out for yourself whether they will be a valu- able daily assistant in your work. If you find that the hundreds of charts, tables, diagrams, cifications and instructions will help you, keep the books, sending $1 a month for 6 months, § HANDY POCKET SIZE GUIDES BIG TYPE-EASY TO READ AND LEARN 1500 PAGES-3700 EXAMPLES Strong, flexible covers—easy to carry in the pocket. Clear white paper. A hand- oome. set of practical. helpful books that every carpenter will be proud to own. Aupets CARPENTERS AND BUILDERS Guipe I j j LAYINGOUT FOUNDATIONS «>?

Condensed Contents of Audel’ of Audel’s New Guides Guide No. 1—Over 431 pages—1200 illustrations - to know the different kinds of wood. — to use the different kinds of w —Comple te de tailed information on nails and screws. —How circular and band saws are handled. —How to use the steel square. —How to sharpen tools. —How to file and set saws. —How to make wood joints. —Complete information regarding joints and joinery. —How to build furniture. —How to make a work bench, -—How to make a mitre box. —How to make a mitre shooting board. —How to plumb and level work. —How to use the chalk line. — How to lay out work. —How to use rules and scales, —How to use all of the carpenter’s tools, with over 900 illustrations showing specifically how. Guide No. 2—Over 455 pages—400 illustrations —How to understand carpenter’s arithmetic. —How to understand geometry. —How to understand trigonome- try. —How to solve mensuration prob- lems. -—How to estimate the strength of timbers. —How to proportion beams. — How to use — instruments. —How to read plans. —How to survey. —How to draw up specifications. — How to estimate cost. —How to build houses, barns, garages, bungalows, etc. Guide No. 3—Over 255 pages—400 illustrations — How to excavate foundations. —How to build foundations. — How to make water-proof. —How to erect post foundations. —How to build forms for con- crete. —How to proportion foundation footings. — How to frame house: —How to set girders oo sills. —How to frame joists. —How to construct a well hole. —How to frame a studding. —How to frame corner posts. —How to lay out and cut braces, —How to attach lath to corner sts. <n to frame temporary and permanent braces. — How to frame girts and ribbands. — How to set window frames. —How to frame partitions. —How to distinguish various types of roofs. —How to use the settings 12, 13 and 17 on the steel square. —How to lay out mitre cuts. —How to use tangents, and full detailed information covering sky lights, scaffold and hoisting. Guide No. 4—Over 448 pages—400 illustrations —How to put on wood, fibre and metal shingles. —How to lay gravel roofs. —How to lay tin roofs. —How to hang doors. —How to frame windows. —How to put on siding. —How to put on exterior trim. How to do cornice work. — How to build stairs. —How to lath. —How to lay floors. —How to put on interior trim. —How to paint. —How to give first aid to the injured.

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16 POPULAR SCIENCE MONTHLY If New Hair Doesnt Grow After Using My Method — Dont Want a Penny! I mean just what I say! I don’t care how thin your hair a care how many treatments you have taken without results. be—I don’t my new dis- covery won’t restore your hair, I don’t want to keep a cent of your money! Furthermore, I’ll send you the evidence of what I have done for others entirely FREE! Just mail the coupon below. By ALOIS MERKE Founder of Famous Merke Institute, Fifth Avenue, New York After many long years ex- perience in treating loss of hair— which included a long appren- ticeship in Heidelberg, Paris, Berlin, Geneva, Cairo, and other centers of scientific research—I have discovered a startling new way to promote hair growth. At the Merke Institute, Fifth Avenue, New York—which I founded—lI have treated scores of prominent stage and social celebrities. People came to me from all parts of the country to gain the benefits of my discovery. Some pay as high as $500 for the results I have brought them Yet now, through a series of ingenious inventions, [ have made it possible for every one to avail themselves of my method —tright in their own homes, and at a cost of only a few cents a day! My Unusual Guarantee! I know you are skeptical. I know that you have tried perhaps dozens of differ- ent remedies and treatments without results. I know that you have wasted time and money on treatments which by their very nature could NEVER restore your hair. All right, Perhaps my treatment cannot help you either. I don’t know. But I do know that it has banished falling hair and dandruff for hundreds of others—often with the first few treatments. I do know that it has already given a new growth of hair to people who long ago had despaired of regaining their hair. And I am so downright positive that it will do the same for you that I am entirely willing to let you try it at my risk—and if it fails to restore your hair, then I'll instantly—and gladly—mail you a check, refunding every cent you have paid me. In other words, I absolutely GUARANTEE to grow new hair on your head—and if I fail, then the test is free. Entirely New Method What is my meth- What Users Say: Letters like the following are received almost every od? It is entirely day by the Merke Insti- new. It is entirely tute, different from any- “In the short time I have thing you ever heard used your treatment I have of. No massaging— gained remarkable results. no singeing—no Dandruff has disappeared entirely. My scalp is new all full of fine new_ hair. A Would not part with my bother of any kind. treatment for 10 times its Yet results are usual- cost.” A. W. B. ly noticeable even after the very first few treatments. Many people have the idea that when the hair falls out and no new hair appears, “mange’’ cures—no unnecessary fuss or ‘‘The top of my head is now almost covered with new hair about one-half inch long. I a — trying five years but cou never ry find anything to make my that the hair roots hair grow until your treat- are always dead. meat” ot. C, I have disproved this. For I have found in many cases which have come under my observation that the hair roots were NOT dead, but merely dormant! Through undernourishment, dandruff and other causes, these starving, shrunken roots had literally gone into a state of “‘suspended ani- mation.” Yet no matter how thin hair may be, it is now pos- sible in a very great many cases to awaken these dormant roots and stimulate an entirely new growth of healthy hair! I KNOW this to be true—because I do it every day. Ordinary measures failed to grow hair because tRey did not penetrate to these dormant roots. To make a tree grow, you would not think of rubbing “growing fluid’’ on the: bark. Instead you would get right to the roots. And so it is with the hair. In all the world there is only one method I know about of penetrating direct to the roots and stimulating them into new activity. And the principle of this method is em- bodied in the treatment that I now offer you on my posi- tive guarantee of satisfactory results, or the trial costs you nothing. The treatment can be used in any home in which there is electricity. Already hundreds of men and women who only recently were troubled with thin falling hair, have through this method acquired hair that is the envy and admiration of their friends. As for dandruff and similar scalp disorders, these often disappear after the first few applications. Remember—I do not ask you to risk ‘‘one penny” trying this treatment. I am perfectly willing to let you ey it on my absolute GUARANTEE—and if after 30 days you are not more than delighted with the growth of hair produced, then I'll gladly return every cent you have paid oo Ae don’t want your money unless I grow hair on your nea Bios Booklet Explains Treatment you will merely fill in and mafl the coupon below I will gaaty send you without cost of obligation—an interesting 2 pose booklet, describing my treatment in detail. his booklet contains much helpful infosmation on the mi of the hair. No matter how thin your hair may be—no matter how little hair remains, this Coie w will prove of deepest interest \4 you. So mail the coupon now—and it sent you by return mail. Allied Merke caaben Tec Dept. 1710, 512 Fifth Avenue, New York City. ALLIED MERKE INSTITUTES, Inc., Dept. 1710, 512 Fifth Avenue, New York. Please send me, without cost or obligation on my part a copy of the new booklet describing in detail the Merke Institute Home Treatment. NMP... oper os oeanelet ona seae con aeniome ence (State whether Mr., Miss or Mrs.) DRE oes cknenenuseecebeunecarneanecece [i cp CELkee cp weeeeke Kee rene sees Gate i wsccccsoe opportunities in the Auto y original copyrigh array instruction covers every o electrical, mechanical. Welding, Garage M t, etc. i TRAIN You AT HOME! Get my training and learn to =m the job? Earn Auto-Experts’ big pay. -~k of Chicago aiee Shops * know wha poke need to suc ve IT YOU! RIGHT IN YOUROWN HOME AUTO BOOK FREE! educated _o; BESS in vel oung or old, find the e e auick fhort Fi ceer ro Feed to to Kt Bret tenting and nauk Toe 4 every student this mon’ B. W. Cooke, Directing Engineer Gbicare Aute Shops—Dept. 725 1553 W. Madison St., Chicago Become More Efficient through coursesin Mathematics, Histor »English, Chemistry, Psychology, lucation, Busi- @ese and 35 other ‘subjects which the University ves by mail. They command credit toward a Shae degree and may be begun at any time. The Gnibersity of Chicage 25 Ellis Hall MONEY AT HOME Start permanent business. Every- thing fare urnished. Work anywhere, only table room requir- le t Po rtrai Money Making Opportunitie. AGENTS aa. SALESM&£N WANTED Costs 25c: a © a. No Ses, No Attachment. ~ Rub keeps Windshield Clear =. nr. Riley pei unnecessary. Corporation, Hartford, —" POLMET—The Wonderful oe cleans all metals without li uid, paste 0} poloth that o xing’ and “Modern. proved by ‘‘Good Housekee Prise F.C. Gale, 15 E Edinboro —sells oo at 25c. Sample St., Bosto AGE iy S~Household necessity, sells quick! By y. rae rofits. Premier Company, Dept troit, oo BUILD permanent business, Men's, Wi Chie dren’s guaranteed shoes direct to wearer. hem sues Manager Allen Shoe Co., 110 Summer, Boston, EST proposition in the Specialty fiel Lykol Paintings, Photo Medallions, and d Novelties have = o ene. pr a i sale. 600% profit, r or details erry Photo Novelt} Corporation, Sect. PS7, 360 Bowery, New York. Jd Lg on agents—50 good men wanted, who earn $50 weekly and up. Our line contains 220 big ie all wool fabrics to retail at = 5 to $47.50 for suits and 6x 0 swat = , By . te hae ance. Big x 9 swatch ou ee. Re . Ferrin, _ 0. Box 1097, Chicago. sani Mer. RUMMAGE Sales make $30 daily. Offer wonderful values. We start you. ‘Wholesale Distribu re 509 Division Street, Chicago. tore,” Dept. 34 SELL Pearl Necklaces, 500% profit. Everyb te one. Easy to sell. Write for a een bottoms Price, “ae — Import Company, 63 Second Avenue, New York. RETIRE in five years, sell our Su = Guim Machine Desi Sk alls or thee’ genta pro! : UW Milwaukee, Wis. . 7 378-20th &K, GET our plan for monogramming automobiles, trucks, hand juggage and all similar — by transfer method; experience unnecessary; exceptiona ‘enon M Accessories Company, Mansfield, Ohio _ GET our free sample case toilet articles, perfumes and specialties. Wonderfully promtante. La Derma Dept. F. St. Louis, Missour ™ AGENTS: Big profits. Best and cheapest window letters made. Easily Septet. Dime ae ave samples, Particulars free. Staibrite Company, 1115 Second Avenue, New York. AGENTS—875.00 Weekly Selling Nustile Guaranteed Hosiery. Your pay daily. You write orders, we deliver and collect. Special monthly bonus. Sample ouutit furn whet. Nustile Hosiery Mills, Dept. 400, Philadelphia, enn, SELL the livest, quickest sell known. Famous “Ha a. self-! stated. ‘Solfo desiersExiplos aud gen stra ‘O dealers. Employ sul its, Exclusiv territory. Make over 490% profit. §S. Berntardt, 148 Chambers Street, New Y AGENTS: Our ae all-wool tailor made suite—o’coats at $31.50 are $20 cheaper than store prices. Fall line greatest ever. Easy to sell, we train you. ; sk in advance. Write for great new sales plan. epson. Dept. 922, 843 Adams, Chicago. NTS: Three necktics boxed singly for $1.00— Searle Sideline "Nulg specialties ever Retail” $2.00. Cash with order. Maxwell, 401 Bldg., Rochester, N. Y. EVERY Ford owner in the world wants this! The Hamer Visible Vaporizer guarantees increased mileage (3 to 8 miles per gallon), more power (40% and bette, quicker prue. 20 0 carbon, smooth moons motor, less life, $4.50; your ills = heat, longer commissio’ on, $3. Visible Vaporizer, Dept. 17, Chamberlain, § $10 DAILY an bens mirrors, plating and refinis lamps, reflectors, autos, beds, chandeliers by new meth Outfits furnished. Write Gunmetal Co., Ave F, De eatur, Illinois. AGENTS—Write for free samples. Sell Madison “Better-Made” Shirts for large Manufacturer direct to wearer. No capital or experience required. Many ear = a and bonus. Madison Mills, 564 Broadway, ew Yor SHYNIT silverplates metals quick and las o—_ le bottle 50c. Agent wanted. Leonard, a a San oo California. i¢F Christmas Cards $1.25, 30% Profit. “Sotleitimns Gar 10c. Wolf, Printer, Lawndale, Philadelphia. SALESMAN—Manufacturer of unique line specialties selling merchants, factories. Building permanent sales organization, attractive plan. Write pocket sample. Greene Corporation, Mt. Morris, N. Y. A Business of Your Own. - Make pe ao hee Glass Name and number plates, medallions, eckerboa' Big illustrated Book Free. E. Palmer, 513 Wooster. 0. FASTEST Selling Specialt a ® ee shoes and moccasins. Fit the whole family. commissions. Repeat orders. Permanent business. Prompt promotion. Free samples if you qualify. Apply Crawford Treat, Bangor, Maine. harges batteries in ten 2 folite Co, St. “WONDERFUL gt a minutes. Gallon free to agents. Radiolite Paul, Minn. AGENTS: $20 8 Gay casily easily earned selling needle books. Costs you 3e to 5c each; sells for 25c, looks = value. 3 assortments sent post; for 25c. ‘Catal a. Needle Book Specialty -» 661 Broadway, or AGENTS: $16 a day. Latest improved portaiie § le talk- ing machine. Does more than machines costing five times its price. Built in just like a suitcase. Fully guaranteed. — 7 ee daily. Write Perry-Ludlow Co., S-1961, Day- GENTS —Guaiity Shoes, quick sellers. Big “commis. sions, immediate returns! Independent business! — orders. Experience unnecessary. | Write full partic Tanners Shoe, 2032 C St., = EASY Money applying monograms on automobiles’ gold initials sim ansferred fro. per; no experien needed. Takes aeotans make $1. cost 5c. Samp! Free. ‘‘Ralco” 327 Harrison Ave., Boston, Mass. B ARE you old at forty? Eee our advertisement on poss 148 of this issue. The ro Thermal ee Main Street, AE ge, Ohio, T it I wap od Hundreds successful Puicdne Bnsinene: experience ne workers. Quickly learned in 10 eo0tT Free boo! Tangley Company Tinie acanttos lowa More Money Making Opportunities on pages 6 to 26 me: put whi inv the his she of dos ide vel las cip she tio lay gr We id pl t su ee ae ae ae of Ga

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itrit furne jadelphia, —— ties ever ardt, 148 or made 1an store train you. les plan, ' $1. 0 01 Searle

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POPULAR SCIENCE MONTHLY 17 How to Invent— - What to Invent. and What to Do About Protecting . and Selling An Invention | LTHOUGH the fact has been universally recognized that In- vention is governed by a few simple, easily acquired, funda- mental principles, no one ever thought of putting these principles in black and white so that everybody interested in invention could read them. In spite of the fact that Thomas A. Edison made his famous statement that invention should be taught as a science, thousands of people continued to work blindly, doggedly, haphazardly to perfect their ideas. But now anyone can learn how to in- vent. Fifteen famous inventors have at last given to the world the laws and prin- ciples of Inventive Science. They have shown every ambitious man and woman how toinvent. They are teaching Inven- tion exactly as other people are teaching lav, medicine, bookkeeping. Instead of spending years groping blindly, instead of wasting your time in useless, heartbreaking drudgery, you learn how to complete your ideas quickly and what to do about them when they are com- pleted. You learn how to think so you are sure to succeed. Everybody Invents

Raymond F. Yates,

—How to develop your imagination —How to develop your ideas —How to get the facts you need for inventions —How to keep legal records of ideas —How to use scientific principles of mechanics —How to avoid wasting time on im- practical inventions —How to apply for a patent —How to organize a company —How to protect your rights —How to market a patent and hundreds of other vitally impor- tant facts which EVERY successful inventor knows and uses.

which must be solved and a fact of me- chanics or science which solves the problem. So, although you may never have thought of it in just this way, every time you solve a problem in your daily life—at home, travel- ing, or in business— you are an inventor; you use the prin- ciples of thought and action which govern the Science of In- vention! You can see, therefore, how easy it is for you to develop your natural instinct to ‘fix things.”” The same processes of thought that almost instinctively told you to fix a rattling win- dow with a wedge can be so well developed that you can learn to invent other things almost as easily and quickly. You know, For a long time it was com- who with fourteen too, that every invention is ° other famous inven- 1 gy eg TET a monly believed that every in- tors now makes it made only by thinking inven- vention was a matter of pure easy for you to learn tively. And every inventor is luck—the result of some happy eal pee sol = agreed that the principles of In- inspiration that suddenly flashed home. ventive Science are so simple, so through a man’s brain, and which made him fabulously rich without the slightest effort or thought. But you can prove for yourself that this is not so. You can prove for yourself that invention is the result of thinking and action along definitely exact, scientific lines. Suppose when you went home tonight you found a window rattling. Through your mind would flash, almost instinctively, a regular order of thoughts which character- ize the conception and completion of every invention the world has ever known. First, you would recognize a problem to be sclved —the rattling of the window. Then you would think of several principles of science or mechanics which would solve your prob- lem. You might think of the. scientific fact that if you poured water on the frame the’ Would would swell and tighten the window. You might think of using a nail: But what you most probably would do would be to use the oldest mechanical principle known to man, the wedge. What Invention is , Brought down to its simplest terms, that is exactly the way every invention has been made—combining two ideas; a problem easy to learn that anyone, regardless of training or education, can develop himself to become a successful in- ventor! With every new advance, with every new discovery that the world experiences, more problems are coming up—and more inventions are needed to solve these prob- lems. Now, as never before, are new inven- tions wanted, and the world will pay a for- tune to the man or woman who gives it just one of the inventions it needs. ; Even little ideas can bring you a_for- tune. Eberhard, who invented the rubber on the end of a pencil, has been paid hun- dreds of thousands of dollars for his simple idea. The man who’ invented the metal tip for shoelaces, the man who conceived i the idea of the “humped” hairpin, the man - who. developed the metal tape measure, ‘all-have achieved success and wealth as . great or greater than the inventors of large machinery. Learn HowtoInvent at Home If you would like to develop your natural inventive ability along money-making lines, instead of trifling with ideas—if you would like to DO something about your ideas instead of letting someone else patent and market them ahead of you, let this great Course in Inventive Science help you. ; Get the advice and help of the fifteen famous inventors who tell you the secrets of inven- tion which you MUST know tobe successful. This is the first course in practical inven- tion that has ever been devised. In simple, easy-to-understand language you are told how successful inventors work; you learn how to think along inventive lines, you learn the short-cuts to successful invention; you learn how to use the secrets of invention that convert a simple little idea into money. No one step in invention has been omitted. Everything you want to know about inven- tion—developing your ideas, securing in- formation you need, how to apply for patents, how to protect your rights, how to sell your invention—are taken up step by step, so that when you have completed the course you have a wealth of infor- mation worth thousands upon thousands of dollars. FREE—New Book on Inventive Science A wonderful new book has just come from the press that tells you all about the Science of Invention. It tells you how to avoid the pitfalls that have brought failure to thousands of would-be inventors. It tells you how to learn the secrets of prac- tical invention, which famous inventors discovered only after years of heart-break- ing effort and discouraging mistakes, and it tells you how to do this in only fifteen minutes of your spare time each day. This fascinating book will be sent to all those who are genuinely interested. Get the ad- vice of those fifteen famous inventors. Let them tell you how you can easily learn the secrets of successful invention. Send for this Book today as only a limited number are available for free distribution. Send the coupon below NOW, cr a letter or postal card will do. There is no cost or obliga- tion. This bureau is not connected in any way with patent attorneys or manufac- turers. Our only work is to help ambitious men and women to develop their inventive ability—to become successful inventors. Bureau of Inventive Science | Dept. 210, Wisner Building, Rochester, N. Y. jo—---cl-lc--f-e-e- | BUREAU OF INVENTIVE SCIENCE | Dept. 210, Wisner Building : | Rochester, New York | Please send me your free book, ‘‘The Science | of Invéntion.” | | INQUIRE 56:56: oi sieroleis weiatois ccieelemarers Age... | PROS ois: 65 6a Ssh eh ellgi eel oiele are eet ere | NE a aac orecd x's ati Woks haionmareioecs State:<i<..% |

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Aviation Brings Quick Success O young men of daring no other field of work offers such a fascina- tion, such high pay, nor such oppor- tunities for quick success as the field of Aviation. As yet, aviation is practically in its infancy. But now is the time to get in. Amazing Opportunities in Airplane Industries In the automobile industry and in the moving picture business hundreds of men got rich by etting in at the start. They made their success fore others woke up. Today, these lines offer no greater opportunities than a hundred and one others. BUT AVIATION IS NEW. Get in while the opportunities are big. All over the country there will be a clamor for trained men. It will not be a question of pay but of getting capable men. Become an Aviation Expert $50 to $100 per Week The study of aviation is almost as fascinating as the actual work. Every lesson is full of in- terest. That is why it is easy to learn aviation. You do not have to make yourself study—it is like reading an interesting book that tells you things you have always wanted toknow. Only one hour each evening will give you the basic training in a surprisingly short time. One student, S. F. McNaughton, Chicago, says: “Your lessons are like a romance, and what is more, after one read- ing, the student gets Fascinating athorough understand- ing. One never tires of —Daring— reading them.” — owers, Pa., another Big aeres student, , says, “I am in- Prepare Now for One surp’ a of These Positions —s ~~ = — can ad from suc vores te $150 por week ractical men for so Paste tes oad ittle cost.” $100 te $300 per week Acseanntiont ae Personal ormous Pp 4 PI acca Instruction $60 to $75 per week by Experienced Men Aeroplane Mechanician Men who have had ac- $40 to $60 per week | tual experience give Aeroplane Inspector ¥9 u personal attention. $50 to $75 per week hey select the lessons, Aeroplane Salesman lectures, blueprints and $5000 per year and up | bulletins. They tell you Aeroplane Assembler things that are essen- $40 to $65 per week | tial in everyday prac- Aeroplane Builder tice. Each lesson is $75 to $200 per week | easy to read and un- derstand. Get Big FREE Book—Now Send coupon below for New Book, just out, “‘Op- portunities in the Airplane Industry. ” It is in- teresting and instructive. It will show you many une you never knew before about aviation. ave but a limited supply of these books— send the coupon before they are all gone. American School of Aviation — Michigan Ave., Dept. 13-67 Chicago, Ill. American School of Aviation 3601 Michigan Ave., Dept. 13-67 Chicago, Ill. Without any obligation, send me your Free Book, “Opportunities in the Airplane Industry’’, also infor- mation about your course in Practical Aeronautics. POPULAR SCIENCE MONTHLY Money Making Opportunities AGENTS AND SALESMEN WANTED a MANUFACTURE Millerite! You've read about this New Ethyl-Super-Fuel Ingredient for Gasolene. Increases Mileage—Saves Gas—Knocks Carbon—FEasily . Your Profit Immense! Stamp brings Valuable Descriptive Formula, Literature ofi this and Mendit, Fabric "Seeedior Cement, Lightning Electrolyte; Rubber Balloons; Amazon Self-vulcanizing Rubber Repair; Pro-Tex-U, Only Guaranteed Fire Extinguisher; Flynox, | few drops kills roomful flies; Marcel, Permanent Hair Curling Fluid; Denta-perl ‘Tooth Whitener. Latest Pure Food Products; Flavors; Beverages; Toilet, Medical; Household; Automobile; Office; Specialties; all tines You'll be glad you received these lists. Miller, Industrial Chemist, Tampa, Florida. THE clothing business is the second largest business in the country. Men have made fortunes in it. So can you if you go into it right. We'll put you into it right without one penny of expense to you and supply every- thing you need to go into the business and clear $100 to $200 right from the start. This is a wonderful op- portunity for the right man. If interested, write at once. Address Dept. 278, Goodwear Chicago, Inc., West Adams Street, at Peoria, Chicago. AGENTS: Send for sworn proof $5 to $15 daily— Introducing Latest Style Guaranteed Hosiery—57 styles —37 colors—Neither experience nor capital needed— Just show samples—take orders—YOUR PAY DAILY— We deliver and collect—All transportation charges paid— Monthly bonus besides—Twelve hour service—Complete outfit furnished—All colors—grades including silks— Early Fall and Winter samples now ready—Macochee Textile Company, Room 15210, Cincinnati, Ohio. AGENTS—I want hustling yo men to take charge of my business in their home neighborhoods. $1.25 an hour for spare time. Permanent positions. Dignified work. No experience or capital required. Costs nothing to start—I furnish everything. Answer quick. Harley Co., 2020-L Harley Bldg., Dayton, Ohio. AGENTS—Steady income. ag! manufacturer of handkerchiefs and dress g wishes representa tive in each locality. ee 4 to COMBUInE®, Big profits, honest ae. Credit given Send _— , Part culars. Freeport Mfg. Co., 24 Main St., Brooklyn, N. Y. Sana LEER Envelope Sealer. Seals 3500 envelopes hour. Amazing invention!! No competition. Retails a $4, 00 only. $20,000 yearly. Red-E Co., Dept. A. F., 100 Boylston, Boston, Mass. STATE Distributor. Wonderful newly invented Pricing System retails $4.90. Tremendous demand!! Big repeat business. $20,000.00 yearly. Millen Mfg. Co., Dept. A. T. Colonial Bldg., Boston, Mass. $2.00 AN Hour for pleasant introductory work among local families. Experience unnecessary; permanent a y starts immediately. Write American ompany, 1988 American Bldg., Cincinnati, O| you can save = on each Auto Tire. Write for par- ticulars. Agents wanted. American Accessories Co., Dept. 1079, Cincinnati, Ohio. AGENTS—Make a dollar an hour. Sell Mendets, a — — for instantly mending leaks in all utensils. mple pack: . free. Collette Mfg. Co., Dept. 467, Ameerdam. nm. LW Jersey inanufacturer wants Salesmen, Agents and Distributors for Tri-Me Spark Plug Combination Tool. For particulars—E. U. Engineering Co., Orange, N. J. AGENTS wanted. $60-3200 a week. — Gold Letters for store windows. or applied. Free Samples beral offer to general —— etallic Letter Co. 434A, North Clark, Chicago BIG Profits. Rubber Specialties. Fifty fast sellers. Everybody needs and buys. $50 weekly easily made. B. & G. Rubber Co., Dept. 643, Pittsburgh, Pa. SALESMAN: If you think in terms of $6000 the first year, write me personally. —— line for retail stores. Nationally advertised. Established concern has unusual opportunity. Liberal weekly advance to producer. Geo. R. Williams, Megr., 1922 Euclid Avenue, Cleveland, Ohio., Dept. 201. SALESMEN—Distributors. ,Right men can make steady income and establish permanent business article that is proved success. Nationally advert Thousands in use. Write or wire—good territory going fast. C.F.8S.CO., 14 N. 10th St., Richmond, Ind. TAILORING Salesmen, $150.00 weekly. Liberal Bonus ont | large commission selling $45.00 All-Wool Suits, $32.50. nion made to order 5 oldest tailors on earth. Satisfaction Guaranteed. xperience un- n Write today for free outfit, exclusive ter- ritory. Wilson Tailoring Co., 936 W. Jackson, Chicago. BRUSH Sales Managers. Both you and your sales- men can make unusual profits selling our standard quality wire-twisted brushes and mops. _ Write Cleve- land Brush & Mop Co., Specialty Dept. B, 8109 Town- send Ave., Cleveland, Ohio. SALESMAN earn $15 to $20 daily selling Manchester Twill garments made to measure, $12.50. Write for eee Chicago Utility Garment Corp., 1432 Altge e BIG money selling gold initials. Quick Sales. Every car owner buys. You charge $1.50—Makce ae 44 every sale. Your profit $20 Daily. No lice No ex- perience. ‘Samples free.” Nulife (P) oe honogram Company, Hartford, Conn. MAKE $17 day—Finest extracts, food products, toilet preparations, household necessities. Credit: sample case free. Write for amazing offer. Perkins Products, B-26, Hastings, Nebr. AGENTS Wanted—Something New—Fire fighter sells easily. Makes a spectacular demonstration; car owners, homes, factories, stores, practically buy on sight. Our men make $10.00 to $50.00 a day. If you wish to b- lish a business of your own with unlimited ibilities for making big money, write us today. Fyr- Co., 282 Fyr-Fyter Bldg., Dayton, Ohio. MAKE extra money. Xmas — folder, bination packs. 10th season. Sell a. Samp Big profits. Ufert, 133 West i5th, New York. AGENTS—Make $15 and more each day selling New All-Weather Coat at $4.98. Full or spare time. Im- proved Mfg. Co., Dept. 910C, Ashland, Ohio. AGENTS Coining Money. $1.40 profit on every $1.50 sale. Monograming Automobiles. Free samples. Worces- ter Monogram Co., Worcester, Mass. le tbe. EN Se ee ea eee a BIG money and fast sales. Every owner buys gold re initials for his auto. You charge $1.50, ee a $1.44, 10 orders daily easy. Information and samples free. Serect..... World Monogram Co., Dept. 25, Newark, N. i? More Money Making Opportunities on pages 6 to 26 Follow this Man! Secret Service Operator 38 Is on the Job! OLLOW him through all the ex- F citement of his chase of the counterfeit gang. See how a crafty operator works. Telltale finger prints on the lamp stand in the mur- dered girl’s room! The detective’s cigarette case is handled by the un- suspecting gangster, and a great mystery is solved. Better than fiction. It’s true, every word of it. No obliga- tion. Just send the coupon. FREE? The Confidential Reports No. 38 Made to His Chief And the best part of it all is this. It may open your eyes to the great future for YOU as a highly paid Finger Print Expert. More men are needed right now. This school has taken men just like you and trained them for high official positions. This is the kind of work you would like. Days full of excitement. Big salaries. Rewards. Can You Meet This Test? Can you read and write? Are you ambitious? Would you give30 minutes aday of your spare time preparing yourself for this profession? Would vou like a life of excitement, » thrilling adventures and high pay? Answer yes ani I’ll show you how to attain all this. wee the coupon and I’ll send the Free Re- rts — also a wonderful illustrated book Paling of the future awaiting you as a Finger Print Expert. T. G. COOKE, Pres. University of Applied Science 1920 Sunnyside Ave., Dept. 13-67, Chicago, Ill. TiITIIIIIItiiiit i i University of Applied Science 1920 Sunnyside Ave., Dept, 13.67, Chicago, Ill. Gentlemen:—Without any obli lustra‘ me your new, fully il " whatever, send Free Eook on Finger ints and your offer of a PREP course in ce na Service any, and the Free Professio Finger Print Outfi Name aed Address Go-- mmo wnnne eo ~~ + -2-- -

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or ex- the ger 1ur- ve’s é€at ion, iga- ined This t ious? pare sion? llin sani > Re- book asa nce o, Til. jenees 0, Il. , send Finger Secret sional rd ed POPULAR SCIENCE MONTHLY 19 Develops new and amazingly easy method of ELECTRICAL TRAININ ‘The Associated Electrical Engineers Famous “Experience Method” Brings a Big New Day in Your Electrical Training You can now become a skilled Electrical Expert and qualify for jobs paying $2,500, $5,000 a year and up, in but a fraction of the time previously necessary The Associated Electrical Engineers, under the direction of Chief Engineer W. N. Littlewood, have developed a marvellous New Method of Elec’ rical Training that you can quickly and easily master right in your own home, in your spare time, that will open wide to you the tremendous opportunities that Electricity offers. This new training in Electricity is the greatest and most revolutionary advance ever made in home study training. There is nothing like it anywhere. The quick success of men trained under the famous A. E. E. Experience Method is amazing. James DuBall, Fort Niagara, Ont., writes: “How you can put so mucn information in such a few lines is beyond me.” Julio Fuentes, Cleveland, Ohio, just beginning his training writes: ‘I am already doing a lot of wiring and repair- ing and making big money.” J. A. Hoekzema, Grand Rapids, Mich., not a third through his training, writes: “I have started my own business and am doing fine.” Hundreds of such letters are pouring in from A. E. E. trained men, who began making money almost from the start. The reason for the remarkable and quick success of the A. E. E. Experience Method of Electrical Training is because It is not the old fashioned ‘‘schooling’’— A. E. E. trained men are experienced men—A, E. E. training in Electricity is electrical experience. Let us send you our big new 48-page Book, ‘Electricity and its Opportunities for you”? which tells all about this mar- vellous new advance in Electrical training. It is too big and too vital a story to try to tellon this page. The book is absolutely free. _ Electricity is the biggest thing in our lives today. No industry has ever grown so tapidly—no other industry presents the wonderful opportunities—not opportunities ve or ten years hence, but right now—for ig money, big jobs, real independence. $3,000, $5,000, $7,500, $10,000 a year and up is being paid to thousands of men in Electricity right now, and the call is for more and more men to keep pace with this tremendous growth. Herbert Hoover says, “that forty billions of dollars will be invested in Electrical Development in the next few years. How many big, new Electrical jobs and opportunities will this tremendous in- vestment create? Electricy needs trained men—thousands of them. Your opportunity is ready for you just as soon as you are ready for it. Elec- tricity is growing faster than men can be trained. Do not waste any more time in the old crowded, low-pay vocations that have no iuture when the great Electrical Industry beckons you. Do not waste time and effort learning Electricity by old, obsolete ‘‘school’’ meth- ods. Life is too short and Electricity needs you now. Write now—today—for our great new book on Electricity and let us tell you of the big new day in Electrical Training—how the A. E. E. Experience Method has taken all the old difficulties and obstacles out of Electricity, and how it will quickly, easily and surely put you into the big- money, big-opportunity, fastest growing industry on earth—electricity. But that is only half the wonderful story of the Associated Electrical Engineers —the world’s greatest and factest growing Electrical training organization. You must know of the many other remarkable and exclusive benefits and advantages it offers to its members. , Let us tell you of our remarkable Free Electrical Business Training Course, and how we not only develop you quickly into a top-notch Electrical Expert, but also train you and help you to cash in on your ability—another great forward step due to the enterprise of the A. E. E. Let us tell you how over 200 highly trained practical Electrical Engineers, holding big, important positions, have certified that A. E. E. Training is Right —no other home training in Electricity has ever received such an acid test. All these great features, and many others—how you gain experience working with real electrical equipment on practi- cal jobs in the A. E. E., for example, are fully described in our great Free book— yours for the asking without any obliga- tion whatever. . If you are really ambitious; if yow want to get into the uncrowded, biggest pay and fastest growing business on earth, then by all means send for this book. Investigate all you want; find out what others have to offer; but whatever you do, do not fail to investigate the many new, exclusive ad- vantages that will be yours as a member of the great Associated Electrical Engineers— the World’s Greatest Electrical Training Organization. This much you owe to your- self. It will cost you but a stamp to investi- gateand itcan well meanthe bigturning point in your whole life, as it has for many others. You can master the A. E. E. Experience Method—you have education enough—we guarantee you full satisfaction on every point—but send for the big free book—that tellsthe wholeremarkableandinspiringstory. Here’s the coupon that will bring you face to face with Big Opportunity. Use it now while it is before you, and resolve to get into the great Electrical Industry where you can give orders instead of taking them. SES SSS eSB Se ete eaeeaeaaaeaacaaeanasd W. N. LITTLEWOOD, Chief Engineer; Associated Electrical Engineers of America, Dept. 204, 537 S. Dearborn Street, Chicago, Ill. I want to know all about the A. E. E. Experience Method of Electrical Training and all the other new and exclusive features of the A. E. E. It is understood that your 48 page book is absolutely free and that I incur no obligation whatever is asking for it. BOMOIE B66 doiicceed coe cansariaonedexnteednee 3 a ners geno ann Pe ere DUALE co vccss* 80006 . ee ee ee “ ahs fn ao -

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POPULAR SCIENCE MONTHLY

$1002 aWee Easy Hours!~ and Your Own Boss HY work on a job that pays demand. And every _ small money and has all day finds new uses for cartoons—in ad- sorts of routine drudgery at- vertising, in the movies and in countless tached to it when thru a remarkable ther ways. Now is the time to study : } d hod v cartoonin _ won- easy, home-study method you can gerful opportunity for you in this un- quickly learn to make cartoons that crowded field.

sell ? Even if you never had a drawing Send for Free Book pencil in your hand, you can learn to Mail coupon today for our handsomely draw this quick, simple way and __ illustrated book, which will be sent you enjoy the fascinating life of a suc- absolutely free of charge. It tells how cessful cartoonist—easy hours—free- YOU can a - dae in a ae dom from routine—your own boss— minutes dally spare time and at 2 Omit e i k ee : k only a few cents a day. Explains about and make as much as $100 a week OF — this amazing method in detail. Tells of more. And you learn right at home our students and their wonderful prog- in your spare moments. You start at ress. Also the real big-money oppor- the very beginning with the simplest tunities that we can qualify you for. fundamentals of cartoon-making. Send for it today! No wasting of time on unnecessary WASHINGTON SCHOOL OF CARTOONING details. Step by step you progress Room 2410, 1113-15th Street, N. W. easily until soon you know how to WASHINGTON, D. C. oe ehlenbie cartoons of every eee mm ae “ae WASHINGTON SCHOOL OF CARTOONING description. Many of our students Room 2410, 1113-15th St., N. W. have sold enough work while studying Washinston, D. C. : a Please send me, without obligation, your Free Booklet to pay for the course many times over. on Cartooning and full details of your home-study method of teaching Cartooning. (Print name plainly) Big Demand for Cartoons Never before has there been such a tremendous call for original cartoons— ; ers and miepannes. cant get “*------------------------------ -oo~ State..-c0--0 enough of them to supply the public If un ter 16, please give age a a a a en ee ees Mr., Miss, Mrs. ND Soo oe oo cae ee cee eee ane eeee ener

BFA Ral ANG Uw S950Q FER! i! SP “Uncle Sam EARN vo $ Mo. | F = EA ; Start at $110 per Mo., ex- $1 400. to $3000 rm ng “mate penses paid, after 3 mos.

i Become spare - time study at Men, Boys, 18 or over home. Hundreds of suc- — Mail Clerks— ee Ar ONCE cessful graduates. You] City Mail Carriers— — FRANKLIN : can’t help but succeed, Postoffice Clerks ag - poche Common ad Dept. N H em RISK | edncatio o* ’ : POSITION GUARANTEED —_ — ~ a . sulficient. tl This coupon, filled out as directed, Our guarantee states that | If we don’t secure you a os? entitles the sender to (1) free specimen tuition will be refunded to | position after completing e* __examination questions; (2) a free copy of our book, you if, upon graduation, |‘course we refund all you “Government Positions and How to Get Them”; (3) agen is Pon yd have paid. We must train | free list of positions now obtainable. $110 per 2. saq-ew Avonlea more men for positions COUPON sine . .- Railway Mail Clerk ($1600 to $2300) Training is simple, No experience ae sary. Write to-day for culars. Specialty Spo wear Co., Dept. H-205, Court pot Brooklyn, New SUCCEED With Your Own mile Processes, Different, Dependable, Profitable. Catalog Free. C. Thaxly Co., Washington, D. C. $5,000 TO $10,000 yearly introducing _ patented article. Wonderful plan. Exclusive territory. Unusual opportunity. Specialty Mfg. Co., Dept. in. 333 State 8St., Detroit, Mich. SALESMEN—Earn $50 $50.00 weekly selling custome made shirts at ready-made shirt prices. 100 latest patterns: price $2.95 up. Shirts individually cut Unconditional guarantee. Custom Bilt Shirt Company, 538 Broadway, N. Y. BIG money and fast sales. Every owner buys gol initials for his auto. You charge $1.50, make $1 10 orders daily easy. Information and samples free. World Monogram Co., Dept. 25, Newark, N. J SELI, union label all-wool made-to-measure bey direct to wearer for $24.50. Scott System, Whol Tailors, 99 Bedford Street, Boston, Mass. = EVERYBODY uses extracts. Sell Duo pDouble strength Extracts. Complete line household Reoer Big repeaters. Write roday. Duo Co., Dept Attica, N. Y. More Money Making Opportunities on pages 6 to 26

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47, East agents for z. $100.00 ed. Bod ory in the 50 Fourth instantly, for 10,000 ‘ofit. Send L. Master- ee * sheepskin ence neces alty Sport New York. —Formulas, », Catalog ae w patented a FF nusual , 333 State —$_—$_—$——— ig custome 100 latest lually cut. , Company, > buys gold nake $1.44 mples free. = suite asure , Wholesale SS eee uble 00 Osties. Dept. E66, aioe unities ' “ . Highe " % 4 : \ ak Professions bd fe 1, : a é > $90 to °150 EVERY WEEK William McClintock, President Master Barbers’ Ass’n of Chicago and proprietor of the highest priced rented shop in the world, says, Moler’s, is Top man in my shop every week. I gladly recommend the Moler System as the proper place for men to POPULAR SCIENCE MONTHLY BARBERING ow One of the st Paid y son, who learned at become successful barbers.’’—WM. McCLINTOCK. I Will Train You in a Few Weeks— Set Up Your Shop in a New Easy Way N what other profession can you start earning $50 to $75 a week right from the start? Barbering always has paid well. But now, with the added women’s trade it has become one of the highest paid professions—right on an equal footing with law, medicine and other lines that require years of college training. And you can now equip yourself for this dignified, clean, pleas- ant work in a few short weeks. You can have advantages over the ordinary barber. For under the famous Moler system you are taught new scientific methods that please men and women and never fail to attract extra business. You are made a specialist in your line—and you get a specialist’s pay. Experts Train You Right There is a Moler school near your home— thirty in all throughout the United States and Canada. Here expert instructors, tecognized by the profession as the most &Xpert in the world, teach you the little secrets that will make you the most sought after barber in your locality—and the best paid. In a few short weeks you become far better trained than the ordinary barber who Must spend two full years as an apprentice. Earn While You Learn And under the Moler system it is possible for you to earn money while you are learn- ing. Thousands of young men acknowledge adebt of gratitude for the help we have given them—help that enabled them to quickly step from the rut of low pay into a hundred dollar a week profession. Your Shop Equipped On Easy Terms We have even worked out a plan whereby you can, if you wish, own your own shop, on easy terms. You can own one of the author- ized Moler shops—part of a national institu- tion. One of our graduates writes, “My shop has doubled its receipts since becoming one of the Moler chain shops.’’ Our national advertising gives you a tremendous advantage. $1,000 a month is not unusual for Moler shop owners. FREE BOOK Learn now how you can quickly become a Moler graduate—an expert in bobbing and marcelling, mechanical massage, electric hair cutting, scientific treatments and all barbering for men and women—and take this short cut to big pay. Other Moler graduates tell of earning $100 to $150 a week. Why not you? The best shops know that Moler graduates mean extra business for them. A Moler diploma takes you anywhere. Our catalog tells you just how you can get this training, much cheaper than you would ever imagine, right in your own locality. This interesting book will be sent you free. Simply mail the coupon. But don’t delay a single day in finding out how you can easily and quickly enter this modern and well paid profession. Get the coupon in the first mail. New Scientific Method Taught Near Your Home Enables You to Cash in On this Amazing Field That Has Been More Than Doubled by Demands of 21 Women Pick Out the Moler School Near You— MAIL COUPON (30 Branches in United States and Canada) New York, N. Y. Chicago, III. Atlanta, Ga. St. Louis, Mo. Memphis, Tenn. Kansas City, Mo. Dallas, Texas Cincinnati, O. Cleveland, O. Detroit, Mich. Denver, Colo. Omaha, Neb. Milwaukee, Wis. New Orleans, La. Houston, Texas San Antonio, Texas Seattle, Wash. Tacoma, Wash. Spokane, Wash. T MOLER SYSTEM OF COLLEGES (Write Nearest Branch. No Street Address Needed.) Please send without obligation your Free Booklet C, and Full information. vA = 5 ® Address....... Lo eetahinieinianiienibaeenins-er meal ae

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all men distrust, many. UPON it once, ou sim- 0 others wonder- ciples to ays, you valuable instruc- 1, simply ir money ,_ “Mak. the post- ie Course our limited ooccenesensnsnere® cocnes ennseeeneent

ck of High School traiaing bars you from a neornde F business career, is simplified and complete High School Course—specially prepa: for home study by leading professors—meets all requirements for entrance to college and the lead- e ore her o matter what your business inclinations may be, you can’t one to succ without spe- ciali training. Let us give you the practical training you need. Check and mail Coupon for Free Bulletin. American School - Drexel Ave. and 58th St. Dept.H775 , Chicago . American School, Dept. H775 Drexel Ave. and 58th St., Chicago Send me full information on the subject checked and how you will help me win success. chitect aaa Business Law Building Contractor....... er sw Auto’ leEngineer _...... Mach. Shop Practice Auto Repairman |...... Mechanical Engineer wa Civil Engineer ose SHOP Superintendent --eerncterel Seainoer oo EM ment Manager

sees. Bi is ineer cert. Pub. Accountant ......Foremanship Accountant & Auditor _...... Sanitary yy need ww. Bookkeeper oe SUrVEyOr & n Draftsman & Designer ....... Tel. & Tel. aoe” wa. Electrical Engineer oo... High Scheo! Graduate .aeneral Education ___...... reless Radio Personal Analysis oveee Undeci: Name ..

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We Teach COMMERCIAL ics FR Meyer Both Company the largest Commercial Art Organization ithe orld offers you a practical training, based upon twenty-five years of success. This nationally known organization each year produces and sells to advertisers over 15,000 commercial drawings, This well paid profession equally open to men and women. Home study instruction. Get Facts Before You Enroll in Any School Ask the Advertising Manager of the leading newspapers in your city, about Meyer Both Company—let them tell you about us. Send four cents in stamps for illustrated book telling of the success of our students. MEYER BOTH COMPANY Michigan Ave. at 20th 35 - CHICAGO, gee Note—To Art and Engraving Firms: Secure artists among our graduates. Write bint HOMEY ¥ your spare time writing show cards. No canvassing or a iting. Write today without

We instruct you fully. obligation for full particulars and free booklet. WEST-ANGUS SHOW CARD SERVICE LIMITED Many satisfied pupils our best reference. 63 Colborne Building, Toronto. Can,

The little matter of 15 cents in stamps or coin will bring you ontrial the PATHFINDER, anlllustrated weekly, published at the Nation's capital, for the Nation; a magazine that prints all the news of the world and tells the truth and only the truth. If you want to keep posted this is your means. If you want a magazine in your home which is entertaining and Will Dring “lesome. the PATHFINDER is yours. If you g appreciate a paper which puts everything clearly, briefly—here itis. Send 15 cents to show that you might like such a magazine and we willsend the PATHFINDER on probation 13 Repent pia issues. bad 15 ome a not repay yg, but we are glad to invest n new iends, THE PATHFINDER, 672 s

POPULAR SCIENCE MONTHLY

23 How I Average $12 a Day in RADIO WORK By Howard Houston “WES, Mr. Crosby, I'll have the set in- stalled tonight ... yes, all ready to ‘listen-in’ . . . sure you'll be able to get Washington by 9 o’clock.”’ Another hour and a half job! And an- other ten dollar bill in my pocket! It all seems like a dream. But let me tell you the whole story from the very start.

A few months ago, I was driving a bread wagon, selling bread to retail stores. I had a good route though, and if I do say so my- self, I had built up a pretty good business. But try as I could thirty-five dollars a week was all I could make that job pay. I’d be working there now it it hadn’t been for Mary. We'd been ‘‘keeping company” for about two years, and everything was all set for our getting married as soon as I would be earning more money. But the old job didn’t hold out much promise—and I didn’t see how I was qualified for any other work that would pay more. It was Mary who gave me the tip. ‘You can’t earn big money,” she said, ‘‘unless you’re some kind of a specialist. Learn some line of work—become an expert in it.’”’” But what business, profession or trade was there that wasn’t overcrowded? Where could an ambitious fellow stand a good chance to earn big money and get ahead. Stenograph- ers, accountants, clerks—all down the line— every well established line of work was overcrowded, and the pay was small. Then Mary said, ‘‘Why not find a new field?” That was a good thought. The men who went into the railroad business early “‘cleaned up.’’ The same was true of the movie game, the automobile business— but what was the coming field? What new development was there that looked like a new promising industry? We both jumped to our feet. “RADIO.” Why hadn’t we thought of it before? All around us was the evidence of the tremend- ous development of Radio. The broadcast- ing stations sprouting up all around—the rapid increase in Radio Stores—new radio manufacturing plants — everybody talking about the latest program. Radio had captured America almost overnight—and thousands of men who were on their toes were due to make fortunes out of it. Thousands of Men Needed The very next day after I had finished my route, I went to several radio business firms. “Sure, there was an opening. Oh, they'd pay big money—but did you know Radio?” That was my cue. Learn Radio. Become a Radio Expert—and I did! Well, that really is my whole story. I’ve only started. I’ve followed the path of least resistance. Sort of built up a business of my own installing, building, and repairing radio sets. Any small job pays me at least $5— and usually $10. I can easily make from $50 to $100 a week—and more as I get my work systematized. What Mary and I have got to decide after our honeymoon—oh, yes, we are soon having a very quiet wedding—what we must decide after that—is which end of Radio will be best. You see, there are dozens of different kinds of work in this field, it’s so big. I’ve already had several offers—one to take charge of a radio department, another with a broadcasting station, another to give radio entertainments, and a good offer as superin- tendent of construction in a radio plant.

“Ahi there’s Washington coming in clear as a bell.” What we want to decide on is which will not only pay the most money now but will lead to the most rapid advancement in the future. Easy to Learn Radio at Home in Spare Time Just a word about this Radio business. Some fellows think you’ve got to have some training before you start to learn Radio. That’s bunk. I didn’t know the difference between an amplifier and a doorknob before I started. But let me give you a tip. Don’t experiment with your radio course. Get the best. The National Radio Institute has been teaching Radio ever since 1914. The govern- ment recognizes its course by allowing credits to its graduates when they are trying for a license, so you see you can be con- fident you're getting the best training possible—and that means a lot. This course is the only absolutely com- plete one now being offered which qualifies for a government first class commercial license. It gets you the bigger paying jobs in Radio. Send for Free Book ‘*RICH REWARDS IN RADIO” Incidentally, the National Radio Insti- tute publish a mighty interesting book on Radio. They send it out without cost to anyone who wants to learn about Radio. It is filled with facts, photos and figures, on The Radio Industry, and tells all about its course which quickly prepares you right at home in spare time for one of the big pay positions in Radio. Take my advice—and Mary’s—and send for that, no matter how little you know of Radio, or what your plans are. For a short time they are offering a reduced rate for those who enroll now. Act promptly and save money. Just mail the coupon today. Address the National Radio In- stitute, Dept. 12KA, Washington, D. C. NATIONAL RADIO INSTITUTE Dept. 12KA, Washington, D. C. Please send me without cost or obligation your Free Book, ‘‘Rich Rewards in Radio,’’ which tells all about the opportunities in Radio, and how spare time study at home will qualify me for a big paying radio position. Also full details on your Free Employment service. PR GSS ibaa nnmw aa aebamalee YO Seen MND se accra ata cain cd hia iad en econo Occupation.......--<« os 2s See wae tense enwabania Se eee

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a Adds ey: oor a Stator a Great School of COYNE Earn $200 to $800 a month! New Enlarged Course I train you on everything from door-bells to powers eaten everthing to make you a 650 to a week EXPERT. You get complete hy 6g training in Circuits, House Wiring, D, C » Armature and Stator Winding, Drafting. ‘ae “frock and Tractor Electrieity, Battery Building and Repairing, and Radio. Everything to make Ae a thoroughly ed BIG PAY, Electrical EXPEL : CHICAGO The Electrical Center of the World The whole world of electricity is open to the COYNE trained Electrical Expert. Come toChicago—the Elec- trical Center of the. World, I pay your fare. Get your training at COYNE—the oldest, largest and best school of practical electricity in the country—endorsed by Electrical Industry. I do not offer a number of individual courses — I give you just one complete course so that you will be an Electrical Expert ——_ of commanding big pay. You can become an pilves and get big 0d in ANY branch of electricity come to COYNE. Learn in 12 Weeks? NOT A CORRESPONDENCE SCHOOL Nobooks or useless theory. I train you on the greatest outlay of electrical a *EREE co of — institution inthe country. I give you SE complete Radio and Auto- motive courses. I also give youFREE a Life Member- ship which enables you to stay longer if you want or to come back at any time and take up anynew work which is constantly beinginstalledto keep my school the most modern at all times. You Don’t Need Education COYNE gives you educa- or Experience tion and experience by actual work—that’s why you don’t need education or experience to start with. Earn While You Learn ? I help students to secure jobs to earn a good part of their living expenses while studying. Send Coupon Now Don’t delay a minute—send that right now for my big free sneee and full Sa of special otter, ACT NO Free R. R. Fare to Chicago LEARN Electricity ’ POPULAR SCIENCE MONTHLY Money Making Opportunities BUSINESS OPPORTUNITIES WE start you in busin furnishing everything; m and women, $80.00 to $100.0 00 weekly Operating our New System Specialty Candy Factories” anywhere. Oppor- tunity lifetime; booklet free. W. Hillyer Ragsdale, Drawer 19, East Orange, N. J. STOP plodding! Be successful. Operate a tire repair shop. Make big profits in any locality. We teach you and furnish eomplete equipments, $100 up. Book of Opportu- = y. free. Haywood’s, 1306 South Oakley Avenue, cago. USED correspondence courses sold, rented and ex- changed. List free. (Courses bought.) Lee Mountain, Pisgah, Alabama. FREE instruction book. Start Mail ae Business home evenings. Pier, 791 Cortlandt St., N. MR. ADVERTISER: Ask to-day for a copy of the “‘Quick-Action Advertising Rate Folder.” It contains some really important facts which will prove interesting and valuable to you. It also tells ‘“‘How You Can Use Popular Science Monthly Profitably.”” You'd like to know, wouldn’t you? Manager, Classified Advertising, Popular Science Monthly, 250 Fourth Ave., New York. LEARN the collection business. Good omer’ janlck results. Interesting booklet, ‘Skillful Copectins, National Collector’s Association, Science Bui ding, — ark, Ohio. BECOME a Foot Correctionist. A New Profession not medical nor chiro a8 All the trade you can attend making $3000 to $10,000 yearly, easy terms for training by mail, no further capital . needed or — to buy, no agency or soliciting. Address Stephenson Labora- tory, 10 Back Bay, Boston, Mass. MR. ADVERTISER: Ask to-day for a copy of the We rages tay Advertising Rate Folder. ” It contains some reall portant facts which will prove interesting and valual et ~ gy you. It also tells “‘How You Can Use Popular Science Monthly Profitably.”’ You’d like to know, wouldn’t you? Address inquiry to the Manager of Classified Advertising, Soulare Science Monthly, 250 Fourth Ave., New York GO into business for ourself. Make money marketing jo specialties under your own labels. We furnish free. National fey FL and show now 3 how. Booklet Selentine 224 Monroe, Ric! Richmond, Virginia. A Sera Kose Dm. ©, office will dignify and in- crease your business. Use ours. Ex ~~. small; benefits, great. Capital Service Company, 2 Pennsylvania Ave. EVERYBODY needs and buys the ‘‘Business Guide.’ Wells cleared $1,150 in 35 Gaye. Send for sample. It’s Free. Nichols Co., Dept. 1B, Naperville, Ill. mg wife can help you run a Mail Order Business. cep, a a resent job, too. Write, Leon Lambert, B70. olutsia, Wichita, Kansas. PATENT Applications filed aa drawing $20; de- ferred $15; strongest claims; prio | rights guarded. Inventor's ‘Service, 11 Broadway, Ni THE Great Wheat Secret. New book showing the cause of wheat swings and how to forecast them. Un- equalled method for traders, 5) tors, millers. Eye- opening folder free; write y. Market Forecaster Co., Dept. B., Box 133, Kansas City, Mo. STOP Dreaming! You cannot attain real success and happiness unless you enjoy your work. We show you what occupation you are it fitted for and guide you step by — until you oan. Booglet free. Vocational Reseasch, roadway, New York. MR. POESTG ETE Ask to-day for a copy of the “Quick-Action Advertising Rate Folder.’’ It contains some really important facts which will peeve interesting and valuable to you. It also tells * You Can Use Popular Science proneny Profitably.”’ You'd like to know, wouldn't you? Manager, Cl. ed Adv verwane. Popular Science Monthly, 250 Fourth —? New Yor! INCH Display Advertisement 166 NERS Thrice $15. Ye Year $50. Wood's Popular Service, Atlantic City. “FOR $10.00 we'll write three catchy classified order ulling advertisements that must bring you business. Rates of profitable magazines included. Mailing lists of mail order buyers, investors,’ agents, etc., at reasonable rates. Marrtinek Companies, Corona, N. Y. MAKE money with your camera. (Lancaste), Box 436, Los Angeles. ARE you old at forty? See our advertisement on page 148 of t issue. The Eleetro Thermal Company, 8 Main St., Steubenville, Ohio. ARTIFICIAL Marble sanitary flooring instructions, ornamental casting, concrete, plaster, pier-mache decorations, garden furniture, ‘statuary, rubber-moulds. 15 years mp engy . &- the ees tae meg and 200 illustrations free. C er, Huntington, N. Y. I MADE $100,000 as Real Estate Specialist. Free information tells how. American Business Builders, Dept. A-3410, 1133 Broadway, New York. as i Pays Well-—Free hr with Suppl ook. Remover formulas $1. “Waters,” 1050 B..49 Detroit. MR. ADVERTISER: Ask to-day for a copy of the “Quick-Action Advertising Rate Folder.” It contains some really important facts which will prove interesting and valuable to you. It also tells ‘“‘How You Can Use Popular Science Monthly ng gy You'd like to know, wouldn’t you? Address your inquiry to: Manager Classified Advertising, — Selonce Monthly, 250 Fourth Ave., New York Come to Chicago—the coi resort city—and be ready for BI BIG MONEY inlsweekel Endorsed by Electrical Industry 1300-1310 W. Harrison St., Dept. 7-136 Chicago Se CM TR RE RE UT OO Oo A eT Coyne Electrical School, Dept. 7-136 1300-1310 W. Harrison St., Chicago Mr. H. C. LEWIS, Pres. Dear Sir:—Please send me free your big new Si and full particulars on free railroad fare offer and two free courses, | 150 MONEY Making Plans Free! Wolverine Bureau, PS-I, Muskegon, Michigan. SUCCEED With Your Own Products—Formulas, Processes. Different, Dependable, Profitable. Catalog Free. C. Thaxly Co., Washington, D. C A BUSINESS offering larger returns than usual lines, $100 starts you. Dept. . Paul Kaye, 149 B’way, N. Y. MR. ADVERTISER: ASK to-day for a& copy of the “Quick-Action Advertising Rate Folder.” It contains some really important facts which will prove interesting and valuable to you. It also tells “‘How You Can Use Popular Science epee d Profitably.’’ You'd like to know, wouldn't you’ Classified Advertising, Popular Science t Jonthty. 350 30 Fourth Ave., New York. PATENTS Procured; Trade Marks Registered—A comprehensive, experienced, prompt service for the pro- tection and development of your ideas. Preliminary ad- viee gladly furnished without charge. Booklet of infor- mation and form for disclosing idea free on request. Richard B. Owen, 44 Owen Bidg., Washington, D.C., or 2276-Z Woolworth Bidg., New York. More Money Making Opportunities on pages 6 to 26 COSTS PROFITS APPROPRIATIONS POLICIES PLANS FOR FINANCING Become an Expert Accountant The profession that pays big incomes There will always be a demand for wel} trained accountants—men whose training combines a knowledge of Auditing, Cost Accounting, Business Law, Organization, Managementand Finance. Few professions offer better opportunities to men of ambition and intelligence. The tremendous business — of thiscountry has created a rich field r the expert. Train at Home Under the LaSalle Problem Method The LaSalle Problem Method will train we by mail under the direct supervision of illiam B. Castenholz, A. "a ~ former comptroller and instructor, Univer. sity of Illinois, member of American Insti- tute of Accountants, and a director of the National Association of Cost Accountants, He is assisted by a staff of 75 instructors— legal staff, organization and management specialists; business efficiency engineers, including 31 C. P. A’s. You will be given whatever training, instruction or review on the sub- ject of bookkeeping you may personally need—and without any extra expense to you. Our big free book on the accountancy profession fully explains how we train you from the ground up, according to your in- dividual needs, from-the si — bookkeeping prin- ciples to the most advanced accounting problems. All text material supplied in the course has been especially prepared in clear, easy-to-understand lan- age, so that you can readily master the principles y home study, Get our free book, which fully describes our expen training course and tells all about C. P. 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POPULAR SCIENCE MONTHLY 25

* Im [=4 Leeman YA , on as] we E _——— “ae a See Professor Michael Pupin, Columbia University, the famous inventor of long distance telephony, describes man as “‘a splendidly organized corporation for transmitting, receiving and distributing messages’’— A HUMAN RADIO. Every individual has this marvelous possibility—he may receive ITS from the most remote ages and farthest regions as well as from the nearest in time and space—but he must be connected up! Nelson’s Loose-Leaf Encyclopaedia furnishes the best possible connection. y —The Book that is Show- ||! _ It not only brings man into communication with the long past and ing Thousands the Way to oe —_ of the sig pag ma informed concerning the events e ° an e progress O e presen ay. Big Money in ELECTRICITY Prog well you at home in a few weeks. Thousands are himself one of the great sources of knowledge and is virtually we taking this short cut to bigger positions. Re- de aes Codaie Radic Dy Jehe di. Piel ining markable method guaranteed by famous scrapping 1s own 0 2frV en adlo. T. onn . mM cy. Cost Lincoln Institute of Technology. Learn_all : ation, branches without previous experience. | Free ssions Employment—unlimited advice—legal binding bition guarantee of satisfaction or money back. siness Write at once for information about complete h field Electrical apparatus and instruments given. Also big new book. No obligation. S. & H. ENGINEERING COMPANY ; Affiliated with the Lincoln Institute of Technology hod 1422 W. Monroe St. Dept. M-16 Chicago, Ill. | train aus * Bm BROOKKEEPERS , G” oasis nivers Toe 11.30 Days We Train Insti- , You To Make +50 Perpetual Loose-Leaf of the Weekly as all S.Govt. RM GR a) 3 see fas tact ENCYCLOPAEDIA tors— \ HE Key to a Big Salary as : . ement hi ‘Jan Income "Tax. Auditor ie &Research Bureau for Special Information neers, € ie given \J to former U. S. 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Nelson Ss Free Research Bureau wuminatjone after completing our coaching ia 30 dayes | : e a . fhe E é 4 - ; a os. a é s sil Sade oantes FOR SCIENTIFIC REPORTS AND SPECIAL INFORMATION AND r n = ee a ae epi gpm ad of Nelson’s is oe to free + 4h. ° + ge membership in this Bureau. at any time you are in doubt on y Sania Assistant Auditor. mie Seen . $2,500 quia, ate or new, write to this Bureau with sha positive varchar that ent posi- pT LR a a ....- 3,000 yas will promptly receive the latest obtainable and most dependable Resident Auditor ........ 3,500 iadehenaiiil aig Teraing ttn 0 3. THE GREAT AMERICAN ENCYCLOPEDIA rsuly Inspector ......... he aioe es 4,500 STUDY AT HOME IN SPARE TIME NELSON’S PERPETUAL LOOSE-LEAF ENCYCLOPAEDIA—The Great | Private business firms will pay you $5,000 up to $10,000 American Reference Work, is published by one of the oldest and largest International after you have had Government experience. You Can- —— “Spa v f a 2 ‘ not Get This Course Anywhere Else. 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“Mary, I Owe It All to You” R WILLIAMS called me into his office to-day and told me he was going to raise my salary $50 a month. ““‘T am glad to give you this oppor- tunity,’ he said, ‘for the best reason in the world. You deserve it. “You may not know it, but I’ve been watching your work ever since the International Correspondence Schools wrote me that you had en- rolled for a course of home study. Keep it up, young man, and you'll go far. I wish we had more men like you.’ “And to think, Mary, I owe it all to you! I might still be drudging along in the same old job at the same old salary if you hadn’t urged me to send in that I. C. S. coupon.’ How about you? Are you always going to work for a small salary? Are you going to waste your natural ability all your life? Or are you going to get ahead in a big way? It all depends on what you do with your spare time. More than 180,000 men are getting ready for promotion right now in the I. C. S. way. Let us tell you what we are doing for them and what we can do for you. Mail the Coupon To-day _— — ese ee eee eee eae ~— es =e ee eee ae ee INTERNATIONAL CORRESPONDENCE SCHOOLS Box 7617-D, Scranton, Penna. Without cost or obligation on my part, please cell me how I can qualify for the ' or in the subject before which I have marked an X: BUSINESS TRAINING COURSES Business Management (1 Salesmanship Industrial Management CL Advertising Personnel Organization H Better Letters Traffic Management Show Card Lettering CiBusiness Law L) Stenography and Typing (JBanking and Banking Law OL) Business English (JAccountancy (including C.P.A.) ( Civil Service Teco Cost Accounting Chee Mail Clerk Bookkeeping Cemmon School Subjects Private Secretar LJ High School Subjects Spanish French Lj Dlustrating TECHNICAL AND INDUSTRIAL COURSES Electrical Engineering O Architect Electric Lighting Cj Architects’ Blue Prints Mechanical Engineer Contractor and Builder Mechanical Draftsman Architectural Draftsman Machine Shop Practice Concrete Builder Railroad Positions Structural Engineer Gas Engine Operating Chemistry (1) Pharmacy Civil Engineer Automobile Work Surveying and Mepping . Motallursy OM 0 Airplane Engines Steam Engineering 3 ‘Radio a eeneorty slated Namc.......... nosis abeccobbsvsnesonnbesbansbotesseenses EER sian PPE iacupasnvssvbvovesksonsomsnsisenccss bund BERN scscssvcncvesssocsoesesssbcasicsses Occupation Persons residing in Canada should send this coupon to the dnternational Correspondence Schools Canadian, Limited, Montreal, Canada POPULAR SCIENCE MONTHLY Money Making Opportunities STAMPS AND COINS NYASSA Giraffes and packet of ea io scarce stamps, Fiume Triangle, large, $1.00 U.S. Rev., Milli- metre scale, perforation gauge and BAL ‘for only 9c. To introduce our Sudden Service approvals. Fennell Stamp Company, Dept. C. Fullerton Bl dg., St. Louis, Mo. FAMOUS Fenway Outfit—-2 triangle stamps, small album, 2 blank approval sheets, 250 hinges, perforation gauge, 5 large French Colonials, 2 special deliveries, ani- mal set, red cross set, packet 55 different, including Abyssinia, Azores, Cape of Good Ho Bosnia, Crete, Congo, ete., 16-page price list, all for 12c ‘to new a prov. al applicants. Fenway Stamp Co., Fenway tation, Boston, Mass. MR. ADVERTISER: Ask to-day for a covy of the “Quick-Action Advertising Rate Folder.”” It contains some a, important facts which will agg voy and valuable to you. It also tells ‘‘How You Can Use Popular Science Monthly Profitably.’’ You'd like to know, wouldn’t you? Address your inquiry to: Manager, Classified Advertising, — Science Monthly, 250 Fourth Ave., New York FOREIGN Stam ary sent free. pany, Schenectady, N. Y. 158 GENUINE Foreign Stamps. Mexico War Issues. Venezuela, Salvador and India Service, Guatemala, China, etec., only 5c. Finest approval sheets 50 to 60%. Agents Wanted. Big 72-p. 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ADVERTISER: Ask to-day for a copy of the *‘Quick-Action Advertising Rate Folder.” It contains some really important facts which will prove interesting and valuable to you. It also tell ‘‘How You Can Use Popular Science Monthly Profitably.”’ You'd like to know. wouldn’t you? Address your inquiry to: Manager, Clas- sified Advertising, Popular Science Monthly, 250 Fourth Avenue, New York. 100 RARE stamps, _all different, bargain lists, Stamp Magazine, everything 7c. eee Niantic, Conn. FREE 25 different U. S. stamps with 60% approvals. 45 different U.S. 10c. Seidenbere Merton, Wis. 33 FOREIGN bills, splendid assortment, $1.00. Otto Oddehon, Independence, Missouri. BRITISH Colonials, 25 for 10c. 100 different foreign, 4c. Set Rheinland as premium for first purchase from approval sheets. Davies Stamp Co., Toledo, O. FREE! Set 10 beautiful stamps, Rhein-Ruhr Views; to approval applicants. Penna. Stamp Co., Manor, Pa. 1000 DIFFERENT Stamps, wonderful — cn $1.00. C. E. 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ADVERTISER: Ask to-day for a copy of the | *Quick-Action Advertising Rate Folder.” It contains some really important facts which wll prove interesting and valuable to you. It also tells ‘“How You Can Use Popular "4 Monthly Profitably.” You’ d like to know, wouldn't you Address your inquiry to: Manager, Classified Advertising, Popular Science Monthly, 250 Fourth Ave., New York. More Money Making Opportunities on pages 6 to 24 Magazines, newspa ers, manufacturers, spend mil- lions every year on com. mercial photographs, The man or woman who knows Modern Photography has an unlimited opportuni for success in this ascinating and big paying profession, During your tit time alone, you can make $75 a week from This picture was made for e catalog of Bathing Suits. 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experienc schools. IN J. M RW! A Name In my 15 yrs have metand d with 46N 1 I will train as well, You will e,I ec- over. thought to A high THIS A. GENUINE R. E. TWIN SUPERDON lo matter what your present occupation is, I can qualify you in a few weeks time to write your own come etin the fascinating, fast-growing, big- , long-profit field of Radio! itself, but your knowledge to turn it into big money quickly. And not only am I r, more complete knowledge I will show you how to apply 000 to $10,000 a Year! Mail in the co have all the fa Millions of dollars a year are now bei suiay radio men not so well trained as to you. You will command $2,000 eee ae i salary or you can take it in"profts ij. J. MENDELS Ousiness all your own. I wi bee Fascinating New Profession am not going to make you a mere radio ic divided ropose to $10,000 a from a real will show you. mechanic. you to handle the big problems of Radio ecause that’s where the bi be qualified in every branch of radio. eet Learn Quickiy—At vome sean inder my personal direction you will learn ickly at home — in spare time. Don’t wait to think this upon at once —and when you cts before you, then give serious my offer and your future. _. The Wonderful SUPERDON r e powered advan roadcast re- ufacturing ceiver.Gets allstations within 3000 mile circle.Mail and have the coupon Now for full details of this wonderful Brought in instrument and how 2 one ofthe pon Now! Today/. ' world’s larg- est technica} e big money lies. ut design b to getit FREE. Mail ail the cou- 1924 A.R.E. IRWIN J. MENDELS Director, AMERICAN Radio Engineers 646 N. Michigan Ave., Dept. 71, Chicago ENDELS Director . Michigan Ave.. D AM Send bie eatalue and Sab piptinelete of ourse me your big catalog and fu cu! of your complete of training. Also tell me more about the ARE T in Superdon Distance Receiver and how I can get it FRE. sssscccccncees MAIL THIS COUPONesxsscncsnsen ‘win Superdon Long Address write. I can make a good penman of you at your home during spare time, no matter where you live or how poorly you now My simplified system has shown thousands the way to g during the past twenty-five years—it CAN and WILL do oe My signatures above show the peg B v A G im sy te than six months after beginning your course THOS. C. SWOPE, Rt 2. Gillespieville, O. GF camel V len, F. 437 Ridge Bidg., beautiful specimens of penmanship showing what others have accomplished by the Tam- blyn System, with testimonials and general information about our course—(Your name elegantly written on a card if you enclose stamp jor postage). Ladies taught as successfully as RITE TODAY W. TAMBLYN Kansas City, Mo., penmanship for YOU— y beautifully illustrated 32-page Book “How to Become a Good Penman” FREEY!! It contains many » address U.S. A. ofa ARITHMETIC oF A practical treatise on electrical calculations ll kinds reduced to a series of rules, all of the simplest forms, and involving only ordinary arithmetic. 200 pp. POPULAR SCIENCE MONTHLY 250 Fourth Avenue ELECTRICITY Price, $1.50. NFW YORK sella. Spare time. WRITE JOKES Earn From $50 To $150 Per Week Priting jokes, epizrams and pumerons or 1 i 'r d terial. Our short course in Humor Writing teaches you to write humorous material that Learn in your spare time—earn in your a stories ‘or ma- Complete marketing plan ard markets furnished. Wr.te today for full particulars American Institute of Humor Office K, 319 Marion Bldg., Cleveland, Ohio Salaries. densed Method. Night Sessions. FINLAY ENGINEERING COLLEGE, Kansas City, Mo. rite for LEARN ENGINEERING Great Demand for Practical-Technical Engineers. 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It shows you so many little tricks that it just comes natural to pick out on the piano any piece you can hum. Beginners and even those who could not learn by the old fashioned method, grasp the Niagara idea readily, and follow through the entire course of twenty lessons quickly. Self-instruction—no teacher required. You learn many newstyles of bass, syncopation, blues, fill-ins; breaks and trick endings. It’s allsoeasy—so interesting that you'll be amazed. A Simple Secret to Success y- zee Be Popular in Every Crowd No need to devote years in Vg) e who can sit down at study to learn piano nowa- any time without notes or days. Special talent unneces- music, reel off the latest jazz sary. Every lesson is so easy, and popular song-hits that Tol € so fascinating that you just entertain folks, is always the “can't keep your hands o center of attraction, the life the piano.” Give it part of of the party, sought after and your spare time for days invited everywhere. Make and you will be playing and entertaining almost before you realize it. No tiresome scales, no arpeggios to learn —no do-re-mi—no difficult lessons or meaningless exercises. You learn a ; accompaniment that applies to the songs you play. Once learned, you have the — for all time—your difficulties are over an Become Master of the Piano Even talented musictians are amazed at the rapid progress of Niagara School students and can’t understand why this method was not thought of years ago. 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POPULAR SCIENCE MONTHLY How I UsE MY Copy or Popular Science MONTHLY! A Prize Contest Announcement Thousands of men in America find Popular Science Monthly a useful, practi- cal aid in the home, office and shop, and p-:s it on to their friends For the best letter of not more than 200 words on this subject — the letter ! telling the most inter- ‘| esting story—POPULAR SCIENCE MONTHLY offers these prizes: $10, first prize; $5, second prize; and my for the ten next best let- - ie ters prizes of $1 each. Con- | test closes October 15th. Tell Us How You Use Your Copy “T THOUGHT you would be interested in know- “‘T cannot refrain from telling you how much real ing how I use my copy of POPULAR SCIENCE pleasure I get from POPULAR SCIENCE Magazine. MonrtTuHLY,” A. L. M., a building contractor of Kansas City, Mo., recently wrote. ‘“‘I use it to build comfort into Kansas City homes. Every month I get from it new ideas on methods of con- struction and hints on built-in features that add attractiveness and salability to the homes I build. There is nothing to compare with POPULAR SCIENCE MONTHLY anywhere.” POPULAR SCIENCE MONTHLY has received thou- sands of such enthusiastic letters from its readers. And its editor would welcome thousands more. They are of immense value to him in selecting for the magazine material you need and can make use of. How do you use your copy of POPULAR’ SCIENCE? Compare some of these experiences with your own. ‘POPULAR SCIENCE is the best of a dozen maga- zines I buy. When it has thoroughly delighted each of the six members of my family, I send it along to my brother in Mexico. After the three in his home read it, it goes to the mess-hall of the mining company he works for. He tells me 34 Americans wait eagerly for it there. That makes 43 who use my copy.—P. W. McG, El Paso, Tex. “Your splendid magazine has completely revolu- tionized teaching of general science for me. It is a live subject now, and all of my pupils eagerly await its monthly arrival.’”—G. L. B., Baltimore, Md. I have been reading it ever since I saw the first copy on the market and I find it is a favorite among my patients. They invariably select it from several other periodicals.”—Dr. R. W. H., Natchez, Miss. ‘The writer is interested in matters mechanical and electrical. And just now I wish to get next to radio in theory and practice and consider the POPULAR SCIENCE MONTHLY the best means of obtaining data. I picked up locally a recent copy and in it alone I gathered more utility than from several books I had purchased for this express purpose.”—W. H., Nigam, Sask., Canada. ON’T you tell us how you use your copy? Read the present issue carefully, and base your letter on its contents, if you care to; or, if you wish, on the use you have made of the many issues you have read. How does the magazine serve you? What features are most useful to you in your home? In your business? Competition closes October 15,1924. A board of editors of this magazine will select the prize- winning letters, and their judgment will be final. Announcement of winners will appear in the January issue. No manuscripts entered in this contest will be returned unless accompanied by a request. Address Contest Editor, Popular Science Monthly, 250 Fourth Avenue, New York City. SERVICE IS THE UNDERLYING POLICY OF POPULAR SCIENCE MONTHLY

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[LY

What Is Your Pet Superstition? Will a broken mirror cause unhappiness? What makes 13 an unlucky number? What is the myth of the four-leaved clover? Why is the horseshoe a “lucky omen’’? Does a cat really have nine lives? Do you believe in the omen of spilled salt? Are pearls unlucky? What does your birthstone mean? Come Search with Us Behind the Pages of History! READ ABOUT —the king who kissed every girl in Normandy —the Queen who enslaved the boy-king Nero —the betrothal of an infant boy and girl —the famous man in his- tory who wore a corset —the superstition that made Napoleon unhappy —the wonderful bard who was blinded by the Greeks —the woman who confessed she was a‘‘‘witch”’ One Person in a Thousand Knows —why we say the stork brings babies —how the kiss originated —why the Egyptians mum- mified their dead —why marriage-rings are worn —the significance of orange blossoms on brides —why black is the color of mourning —why Chinese women com- press their feet —why the Egyptians wof- shipped the snake —why cannibalism started

man existence! All through the many ages and stages of man’s development! : The dawn of love, the beginning of faith, the discovery of voice, the early struggles with the forces of nature, the miracle of birth, the mystery of death, the germ of superstition, customs and habits of life--the powerful and inspir- ing story of man’s personal develop- ment at last in one astounding volume! What do you really know about yourself? When did man stand erect upon the earth for the first time? How old is human marriage? What is religion? Why do we clothe our- selves? How did man discover that he had a soul? Here is one of the most fearless and truthful discussions of human nature ever written. It tells you thousands of fascinating tales about yourself— startling, extraordinary things you never suspected. Illustrated not only with remarkable pen sketches and color drawings, but with hun- dreds of actual photographs. Man’s Habits and Instincts Traced Back to Their Source All civilization is but a thin veneer over the surface of savagery. The habits, customs, impressions, fears, impulses and passions accumulated by our ancestors since the beginning of life still slumber within us. For instance, there existed in the dawn of life a human pairing-off system which took place at a time that corresponds to what is now June. That accounts for the modern urge to marry in June. B'== to the very cradle of hu-

POPULAR SCIENCE MONTHLY The whole amazing story of human life / . , ee Similarly, we throw rice after the Ke bride because it satisfies a certain primitive impulse, and we dare not say in words what this curious old custom suggests. SEND NO MONEY We believe that ‘‘The Customs of Mankind” is one of the most interest- ing and important books of the year, and to introduce it properly we are making a very extraordinary pre- publication offer. Let us have your name and address to enter on the advance list to receive a copy of ‘“The Customs of Mankind” as soon as it is off press. When it arrives, give the postman only $2.98 in full payment for a book that would ordinarily sell for $5.00. You have the privilege of returning the book any time within 5 days and having your money refunded if you are not amazed and delighted. Be sure to get your copy of this beautiful first edition at the special price. Use this coupon today— Now. Nelson Doubleday, Inc., Dept. A-2510, Garden City, New

York. ee we ce ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee ee oe | NELSON DOUBLEDAY, Inc., Dept. A-2510, Garden City, N. Y. You may enter my name on the special advance list to receive one of the first copies of ‘‘The Customs of Mankind” by Lillian Eichler. Under the terms of your special pre-publication offer, I will give the postman only $2.98 (plus few cents postage) in full payment on arrival—for the $5.00 book. It is understood that I have the privilege of returning the book any time within 5 days and having my money refunded if I am not swept away by its beauty and fascination. I am to be the sole judge. Pde sa<sc2s Scadds.<Wetsi nocdcsesumeennnnsogaeans Geen Check this square if you want this book with the beautiful full-leather i oO binding at $4.98, with same return privilege.

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POPULAR SCIENCE MONTHLY

ee ee ar we id pot ee es. SOARS ~ rr? RK % ie SESS EEY SA, *S Aang PAA AA Sena exclusive features of the Navy lype Headset am aa Pi y

= Fe = d 7 \ vv me | A~U, My WO extra technical developments and one extra testing e——emme | cloth coverin operation! These add clarity and distance. These are = _ S ' ; == B | B ~ Braided copper the three exclusive features which make the Brandes Navy = & || tinsel radio-fre-| Type the ideal long distance headset. <— 3 7 . . e SS “ieee 4 shield —The development of the braided copper tinsel radio- meee | —Headset . . . et & eran wee frequency shield {shown at the left} surrounds the meee || | ductors(+and-) oe BBs LN mn og conductor cords and grounds all radio-frequency currents Gop ae : which might cause detoning effects in the receivers. g 4 “2 an ¢ ° ee e ° ° . And in addition, it eliminates cord capacity.

Ay B.—The use of inside terminals, so designed that the cords may be removed or replaced without taking off the cap of the receiver or in any way disturbing the perfectly matched tone. 3. —A very delicate testing operation matches the tone of the two receivers so that both ears hear exactly the same sound at the same instant. % My Ske ae "Yecies ee a ee a CU ey

ye ero NOK 1

aged "1 We Wy \ / " ee t 5 ey Pa oe, (hi cet sti ag Sica ne st

And to assure absolute perfection of every detail, every Navy Type Headset must pass 22 different tests and inspections.

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POPULAR SCIENCE MONTHLY ssued To. POPULAR SCIENCE INSTITUTE OF STANDARDS > Certificate of Approval =, by the PopuLar Science INsTITUTE OF STANDARDS for the following products CATE remains in force. Tests and inspections by the Engineers of the Popurar Science Institute oF Stanparvs have established that the above products meet the standards of the IwstrtuTE as of sound quality, good workmanship and materials and will perform satisfactorily the work for which they are designed. The Manufacturer is entitled to use the seal of the Instrrute in connection with approved products so long as this Ceatin- The purpose of the Popuzas Science Institute oF Stan. DARDS 1s to enable the readers of Porutar Science MontHiy to purchase mechanical and electrical equipment that has been found reliable by scientific tests and inspections. If at any time tests and inspections by the Engineers of the Porvuiar Science Institute or Stanvanrps of any approved product show that such product has fallen below the standards of the Instrrute, the Certiricate oF Arprovar for such product will be revoked. Poruar Science Institute or STANDARDS DIRECTOR Advertisers whose prod- ucts meet the standards of the INsTITUTE are awarded this CERTIFICATE OF APPROVAL and are entitled to use the seal, shown below, on their products and advertising. CLAIMS IN TOOL AND RADIO ADVERTISING GUARANTEED By HAZEN G. TYLER, Sc.D., M.E. Associate Director of the Popular Science Institute of Standards N THESE days of superlatives and | exaggerated statements, most people go through life discounting all they hear and read. But the readers of PoPULAR SCIENCE MONTHLY can accept all claims made in radio and tool ad- vertisements at their full value. THE POPULAR SCIENCE INSTITUTE OF STAND- ARDS tests and approves every radio and tool product advertised. Then THE IN- STITUTE goes a step further—it guarantees the absolute truth of the statements made concerning such products in POPULAR SCIENCE MONTHLY. Before an advertisement is inserted in the magazine it is carefully gone over by the Director of THE INSTITUTE and the engineer who conducted the test on the product advertised. The first claims to be checked are the technical assertions concerning the advertised article. Any technical statements that do not agree with the results of our tests are eliminated or modified. Then all superlatives are weeded out. This applies to either flat superlatives or insinuated superlatives. Our tests are comparative, but as THE INSTITUTE tests only those products offered for advertis- ing in POPULAR SCIENCE MONTHLY, this does not, obviously, include every product In any certain line of manufacture. And unless exhaustive comparative tests were made on every product, we could not truthfully say which is the best. Furthermore, comparative claims— either direct comparisons or comparisons by implication—that are not substan- tiated by our tests or that are unfair to other manufacturers, are eliminated. Inaddition tothesethree points, allradio and tool advertising is checked as to hon- esty and fairness of general claims made. Ty x © POPULAR SCIENCE Monthly Guarantee The above seal on an advertisement indicates that the products referred to have been approved after test by the Popular Science Institute of Standards. Popular Science Monthly guaran- tees every article of merchandise advertised in its columns. Readers who buy products advertised in Pop- ular Science Monthly may expect that these products will give abso- lute satisfaction under normal and proper use. Our readers in buying these products are guaranteed this satisfaction by Popular Science Monthly. THE PUBLISHERS. aad The aim of THE POPULAR SCIENCE IN- STITUTE OF STANDARDS is to guide the readers of the magazine in purchasing equipment that is of good quality and that will give satisfactory results in proportion to the price asked. It is not a bureau for the establishment of standards whereby the products of competitive concerns can be compared and the supreme product in each of the many lines of manufacture picked. Therefore, when a tool manufacturer makes the statement in his advertising that his is “the finest tool made,’ THE INSTITUTE cannot put its seal of approval on such a claim. ? Keeping in mind that the seal of ap- proval of THE INSTITUTE is upon every word in the tool and radio advertisements as well as upon the products featured, the readers of POPULAR SCIENCE MONTHLY can take the claims made by advertisers at more than their face value, rather than at a discount. Only tool and radio products specifi- cally advertised in POPULAR SCIENCE MONTHLY are tested and approved by THE INSTITUTE. The approval does not include products advertised through radio and tool catalogs. Send for list of Approved Products POPULAR SCIENCE MONTHLY will be glad to furnish a list of Radio and Tool Manufacturers whose products have been approved by THE INSTITUTE.

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POPULAR SCIENCE MONTHLY

*RADE MARK re BROADCAST Receiver that marks Mea Spas or another long step forward in site pine and <ypaearerBe* radio design and establishes a new set evergreens. : Mi” Wace . oA —Confucius of standards in craftsmanship.

In the coming cald season Write for literature be not surpassed by thy neighbor —set the pacewith your Grebe Synchrophase. es H. (GREBE & é OMP ANY, INC. Van Wyck Bilvd., Richmond Hill, N.Y. Western Branch: 451 East 3rd St., Los Angeles, Cal.

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POPULAR SCIENCE MONTHLY SUMNER N. BLOSSOM, Editor October, 1924 The World’s Greatest Adventure, a Triumph for the Airplane By Mayor William N. Hensley, Jr., U. the first airplane flight across the American con- tinent. His trip—from New York to Pasadena, Calif.— took 54 days, and was accom- plished only by the most amazing exertions and in- genuities. For miles and miles at certain stages of his journey, for example, it was necessary for him to guide himself by following railroad cars, the roofs of which were painted with sym- bols that he could recognize from the Asse ir. Here and “f there he had to place his craft on a flat car to be trans- ported for a few miles over territory that seemed to offer especial hazards to an airman. lis longest continuous fight was 133 miles. So many repairs were made to his craft at his imumerable forced landings that it was in avirtually rebuilt plane that he finished his fight. That Rodgers triumphed over such difficulties and reached his destination is to his everlasting credit. He was a pathfinder, a pioneer, and as such richly de- erves his place in aviation history. [' 1911 Cal Rodgers made In the foreground is the first of the Douglas air cruisers designed and built for the round-the-world flight of Army airmen by Donald Douglas, an American engineer. Their wonderful performances over land and sea, in all kinds of weather, and their victories over the tremendous obstacles of the world’s greatest adventure, have been due in large measure, says Major Hensley, to the Liberty Motor— an engine that is a triumph of American industry, ingenuity and patience. During the war the average airplane flight was two hours Today the world cruisers have proved GUPPOSE, though, as Rodgers stepped from his plane at the end of his journey, some one had fered the prediction that with- "Madozen years airmen would taverse approximately the same toute in a single day? Suppose the speaker suggested that with- na dozen years aviators would be circling the globe? Such a man, I am sure, would have been regarded as an impractical dreamer, if hot a fit candidate for the madhouse. To have suggested at that time even that the arplane some day would match a railroad Scomotive in efficiency would have been 4 absurdity. And yet these things ere not merely ¢ for a distance of 150 miles. capable of 500 or 1000 miles at a hop, continuously. and efficiency they have left the steam locomotive far behind If you have any doubts about the commercial future of the airplane, this absorbing article by the Commander of Mitchel Field, N. Y., will soon dispel them. dramatic story of how the American airplane has proved itself, he speaks with the authority of one who is familiar with every phase of aviation science. commanding officer of a great aviation center, a skilful airplane pilot, an engineer, and inventor, but he is one of the foremost airship pilots of the U. S. Army Air Service. admitted possibilities today; they are actualities. The modern airplane already has left the locomotive far behind. Toa skilled airman today a transcontinental flight means scarcely more than a trip of 100 miles over concrete highways does to the owner of a well-conditioned automo- bile. Every day mail is carried by air- plane between New York and San In telling the Not only is he the In endurance a. Francisco. Only a few weeks ago Lieutenant Maughan flew from the Atlantic to the Pacific between daylight and dark—the time that would be consumed by a fast rail- road train in crossing a couple of states. And even a round-the-world flight is essayed by the present-day aviator with no misgivings. [* IS probably unnecessary to say that some amazing advances must have hap- pened in the field of aero- nautics since 1911, to make possible such an_ epochal undertaking as the world flight of the U.S. Army aviators, the most ad- venturous air voyage ever attempted by man. Those whose interest in aviation is only casual, have jumped to the conclusion that most drastic changes in design and construc- tion must have been > made to transform the airplane from a “flaming coffin,” as it was frequently called in the past, into a speedy, practicable, safe, dependable craft capable of operating with unchanging efficiency in tropic heat, in arctic cold, in the high winds and fogs of the northern oceans, or in the dead calms of southern seas. I know this to be the opinion of the layman, for many have expressed it to me since the round-the-world fliers “‘hopped off” from Santa Monica, Calif., on the first leg of their journey. It may be surprising, then, for me to say that, in my opin- ion, a development in one single phase of aviation, more than any other factor, has been responsible for the really amazing success of the round-the-world flight. This development, which fore- shadows a speedy utilization of the air- plane for general commercial purposes, is the Liberty Motor. The story of the Liberty motor has elements that are actually dramatic. It 33

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POPULAR SCIENCE MONTHLY , heal i > ~~ SHANGIA! —>* HONG.KONGSO CALCUTTA — FUNEXPLORED t LOST AG ae .@ eo ANGELES Tote AN TART 4 “ea . ~ @t is ST290 an ) ay N ' . Ny a <a "WASHINGTON ; o

When the U. S. Army aviators hoz 724d of from Santa “eo AREA “ ¥ rd 4 oy Ke An AVIGTUT ’ « , f - W,OLRIGOLLCT LABRADOR ' oF oe a;

a new epoch in world commerce. The map above shows Monica, Calif., just west of Los Angeles, on March 17, for their flight around the world, they embarked on one of the most remarkable adventures ever undertaken by man on land or sea, or in the air—an achievement that marks the path of the modern Magellans, a distance of from 25,000 to 26,000 miles, over which they have proved the airplane to be a speedy, safe, and dependable craft. At the right is Lieut. Lowell H. Smith, flight commander is the story of Cinderella, of the Ugly Duckling, the familiar novelist’s theme of the poor young hero who surmounts in- credible obstacles, worked out once more in actuality. The Liberty motor, as you may recall, was developed first as a war measure, and was built in large quantity during the intensive effort to equip the American Expeditionary Forces. To say that the motor was unsatisfactory to Govern- ment aviation experts is to express the thing mildly. New flaws and defects in the apparatus were discovered almost daily. I am probably safe in saying that had there been available to the Army Air Service another type of motor, had there been an appropriation sufficient to finance the development of a new type, the Liberty motor would have beet scrapped as soon as the war was over. It happened, though, that neither was the case. Something around 10,000 Liberty motors were on hand, and, under the circumstances, the obvious and sensi ble thing was to make the best of them. And it was then that the Ugly Duck- ling began to evidence unmistakable (Continued on page 141) “ [ throu find } aston presi seare exper “But our r ace} “mp figms his a 0n, “ work prese desig time “ V: oper Firs' wits gaso calle

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ve been vas over. ther was 1 10,000 id, under nd sensi- ’ them. ly Duck- istakable POPULAR SCIENCE MONTHLY A New Era in Automobile Construction How your car is put under the microscope, tested, analyzed, and assayed in a great research laboratory—Astonishing plans to make your motoring safer and more comfortable in the future— A dramatic story of science and_ business By Edward Mott Woolley out of the future the automobile of 10 years hence, and drive it today through our streets of Dayton, you would fnd yourself the center of incredulity and astonishment,” said Charles F. Kettering, president of the General Motors Re- garch Corporation, which has its great aperimental plant near that Ohio city. “But if you drove it out to our laboratory, wrresearch men would be quite ready to accept it. “The scientist lives among fgments often years ahead of I BY some magic, you could bring form, that cooling would be accomplished in new ways, or that some new propelling force might be in use. Many things are possible, and here in this laboratory we are searching the future with our knowl- edge of today. We have built entire cars for experimental purposes and _ tried them out on the road; but for the most part we are hunting piecemeal for better ways of making automobiles, and for better parts of lighter weight. Anything connected with the improvement of that city I found the laboratories, housed in a building 1000 feet long, part of which was used during the war for making airplanes. This great workshop today contains the embryonic car of a decade hence. In all of its far-reaching departments are crude, undeveloped parts of this car of the future. The rooms are haunted not only by engineers, but by all the shadowy pos- sibilities of inventive imagination. Little by little the assembling process goes on. Although the laboratories contain all the hisage,”’ Mr. Kettering went on,“and here in our scientific workshop we know that the present cycle of automobile design and capacity must in time run out. “Various causes already are operating to bring this about. First, refiners are at their wits’ end to produce enough gasoline to operate the so- alld modern automobile and truck. The wanton con- sumption of horsepower in propelling heavy motor ve- hides portends disaster. In- vestigations have shown that the average automobile car- tes on its every-day travels the equivalent of only 14% yrsons. The streets of our lage cities are absurdly con- gested with these great empty whicles. The problem is tpifed by the recent at- tmpt of New York to pre- wnt vacant taxicabs from Today’s Mechanical Marvels essentials necessary for the building of automobiles, the tremendous rush of the mod- ° ern factory is lacking. Lei- Eclipsed Tomorrow surely science takes the place = . of speeding production. JMORROW 8 car will compare Chemistry, physics, mechan- with today’s as does a locomotive ics, metallurgy, electricity, searchlight with a tallow candle,’”’ Charles I’. Kettering, head of the General Motors Research Corporation, told Mr. Woolley. “But don’t forget that the machine we are experimenting with is already mar- velous beyond conception. the engines of some cars fire 16,000 shots a minute, while the most rapid firing gun fires less than 1250. Every one of these 16,000 explosions is caused by a spark delivered on schedule time! “This is the wonderful machine we are seeking to improve.” For instance, and allied sciences all join forces here. VERY research labora- tory works on _ possi- bilities not yet realized. Re- search men are guarded in discussing them. Mr. Ketter- ing referred to science merely in a general way, with no special reference to his labor- atory, when he made a guess that new substances would be discovered that would have a bearing on automo- biles and other things.. As an example, he cited the pos- sibility of flexible glass. In- deed, a substance already using the streets for pas- sngers. “The wise automobile manufacturer tads, along the road of progress, signs that point the way to a smaller, lighter, ks expensive car, signs that point the wy to a new era in automobile con- stuction. “Ishould not like to build in your mind, owever, any definite picture of the liture car,” he added. “It would be a fless to predict, for example, that the shift would be done away with—that you wuld have no gears to worry you. In- ventors long have sought such a millen- tium for gas-driven cars. The electric hift and hydraulic transmission already ve been tried, with a variety of troubles. “I should hesitate to prophesy that the eigine would take a radically different. automobiles is in line with our work. “We have 300 engineers constantly on the job. It does not matter whether we get ideas on frictionless bearings, new materials for brake bands, better prin- ciples of ignition, new alloys, or original paint. No matter how grotesque or in- tangible a thought seems at its inception, it carries a possibility. We don’t want to think in little orbits. We would rather begin in the big orbit and compress it into the practicable as experiment com- pels us, than to think in small circles that never get any bigger.” I had gone to Dayton for POPULAR SCIENCE MONTHLY to talk with Mr. Kettering, and to see one of the greatest of research institutions. Six miles out of has come into use for auto- mobile windows that hints at flexible glass in reality. I am thrown on my own responsibility when I suggest that science has not reached the end of its work with rubber, for example. Is it too much to imagine that we may have an airless tire as resilient as the present pneumatic ore? Or that alloys will be found to render steel immune to crystallization—literally unbreakable? That the shifting of gears in gasoline cars will be wholly eliminated? Today we are at the peak of an engineering attack upon this enigma. That some new fuel or other power will come out of a future still unexplored? That new paints and other finishes will be found as radically different as a

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36 recently discovered paint differs from that of yesteryear? That a gallon of gasoline will carry a ear 50 or even 100 miles, or that new lubricating contrivances will be devised to cut down friction tremendously? The present frictionless bearing, I believe, is accomplished by absorption of oil into the bearings? That lights will be invented no more dazzling than daylight? I cannot put all these possibilities into Mr. Kettering’s mouth. They suggest themselves to me out of the very atmos- POPULAR SCIENCE MONTHLY To the user, who is not so much in- terested in the wonders of science and mechanics, the great gain in all this research will be lowered cost. About the first thing they showed me in this huge series of laboratories was the section fitted with gas-heated or electric furnaces, in which are carried on the ex- periments in the heat treatment of metal. “A few decades ago, steel and iron were simply steel and iron,” said Mr. Kettering. ‘‘So far as the consumer was concerned, nothing was known of the composition. Steel manufacturers had their own ideas, Charles F. Kettering, who, as president of the General Motors Research Laboratory, is directing the efforts of a large staff of engineers seeking to answer the question: What sort of automobiles are we to have in the future? Through exhaustive research they are trying to determine just how the present-day automobile may be improved, and what changes are necessary that our cars may be safer and more comfortable phere of that great research laboratory. I asked Mr. Kettering ‘about balloon tires and their probable effect on the design and weight of the future automo- bile. He preferred not to discuss them be- yond saying that they gave evidence of possibilities in that direction. |S wen I am reduced again to my individual responsibility. Basing my premises merely on the general feeling in automotive circles, it would appear that balloon tires are perhaps the out- standing development just now in the fashioning of the coming car. What could have a greater influence on car weight, and consequently on its design, than tires that carry a car on an air pressure so greatly diminished? So it seems that there must come radical changes in the char- acter of many heavy-car parts—the steering gear, for instance. In like manner, every such distinct de- parture from conventional standards up- sets the automobile all through. but their formulas were secret. “The railroads were using extra- ordinarily heavy metal parts be- cause they lacked knowledge of the strength to be ob- tained through heat treatment and alloys. It is said that a college pro- fessor out of a job talked Andrew Carnegie into em- ploying him to do research work in steel —— out of which came unex- pected scientific information. ing of the autv- mobile the need developed rapidly for metals that “With the com-— say that they fill the gaps in the molecular formation of the metal, decreasing crys. tallization and breakage. “Up to that time this sort of thing had been almost all guesswork. The heater would squint through a peephole into the furnace, and when the piece of metal was ‘cherry red,’ or a particular tinge of blye he would take it out. On these colors depended the strength and toughness of the part. “Q@CIENCE has revolutionized heat treatment so that today the exact temperature for each particular use js standardized. We know just how long aq given automobile part should remain jp the furnace at a specified temperature— perhaps 2000 degrees or more. ““We have electrical devices for main- taining this temperature automatically, and recording devices that show the pyrometer man whether or not they are working properly. ‘Without these discoveries in the heat treatment of metal it would have been impossible to develop the modern auto- mobile. The axles, springs, and steering gear would not stand up under the terrific strains. “There are now about 15 varieties or compositions of steel in a single automo- bile, and the industry has been steadily working toward the standardization of varieties, so that every part can be duplicated again and again; so that axle and spring strength will not be sporadic, and parts can be manufactured month after month and year after year with the same qualities of endurance. Sixty dif- ferent steels now have been standardized by the Society of Automotive Engineers. a . ap rere Te re This doesn’t look much like an automobile; yet the instruments shown here analyze far more exactly than could observation of a real would withstand unheard-of blows, pulls and torsions. The metals on the market were wholly unfit. Thus there came about a new scientific research not only into the composition of metals, but into their molecular structure as affected by heat treatment. “The effect of alloys, in a word, may be likened to that of cement. You might car just how the air circulates about a running engine. Thus the engineers determine the most efficient designs for fans and manifolds **Perhaps next in importance comes the subject of fuel to propel the machine fabricated out of the heat-treated steel,’ said Mr. Kettering. “Ten years ago gasoline was largely gasoline. Five years ago it was not s0 much gasoline. Today the overwhelming demand for automobile fuel is being met only by the utilization of gasoline of gre: “ ma! onl: wo! all. pre: bee the whi mo mel sati tio! 7,0! ling

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lecular & crys- ing had heater nto the tal was of blue, > colors ness of 1 heat e exact use js long a nain in ature— > main- tically, »w the hey are he heat re been n auto- steering terrific eties or tutomo- steadily tion of can be iat axle poradic, month vith the xty dif- lardized gineers, i ‘ - _—p ymes the machine d steel,” . largely s not so rhelming sing met oline of greatly reduced power and efficiency. “This is not a reflection on the gasoline manufacturers. On the contrary, it is only through their continued scientific work that the demand of today is met at all. Except for gasoline chemistry, the present type of automobile would have heen useless long ago. The invention of the so-called cracking process, through which petroleum was made to yield much more gasoline, was one of the accomplish- ments that kept the supply up to the in- satiable demand. In 1923 the consump- tion of gasoline in the United States was 7,000,000,000 gallons—more than doub- ling since 1918! “-HE problem of theautomobile manu- facturer has been to produce an ever-changing type of carburetor that would utilize the constantly lowering grade of fuel. “All automobile manufacturers want a carburetor that will start the engine instantly at 10 below zero, with never a cough. “The carburetor, however, is only one element,’ Mr. Kettering explained. ‘‘In improving the carburetor and in engine studies in general, we began to fathom the mystery of the knock. “To the ordinary driver the knocking of an automobile en- gine is a fact bounded by the deepest mystery—a mystery that he never could solve. He takes it to the ordinary garage man, who looks wise, but who knows little more about it than the user. “The scientific man, however, found the cause of the knock and understood perfectly the how and why of it But to discover a way of stopping it con- sumed several years of research. Thomas C. Midgely, Jr.,vice- president of the General Motors Chemical Company, happens to be the man who found how to stop the knock by-the use of ethyl gas, and how to make the process a commercial possi- bility. “THE automobile industry al- ways has been a race between pro- duction of cars and the production of POPULAR SCIENCE MONTHLY their trains with in- ternal combustion engines. This will come about unless the makers of steam engines evolve radi- cal improvements.” They took me in- to one of the labora- tories and gave a demonstration of ethyl gas with a gas- oline engine. Ona fair quality of gas- oline the engine ran smoothly; but when the fuel pipe was shifted to a mixture containing half gas- oline and half kero- sene, in a few sec- onds it began to knock tremendously. Then one of Mr. Kettering’smentook a common medicine dropper and dipped Probably you never think of the chemistry of the auto- mobile, but to the research engineer it is of prime im- portance. Thus, the weighing in delicate scales of in- finitesimal samples of chem- icals from exhaust gases, or bits of dust that might be sucked in by the carburetor and enter the cylinders, might lead to important discoveries for improving the car design In the automotive laboratory, machines such as this test to destruc- tion all materials used in building motor-cars, from the fabric that the tops are made of, the seats, and floor coverings, to the steel that goes into the crankshafts. The materials are pressed, torn and twisted until they give way, to determine their strength and quality, and so make your automobile safer to ride in accepted this charmed fuel and ran smoothly again. We came to the large laboratory garage in which all the employees bear the distinction of knowing the very soul of the automobile. Standing about on the expansive cement floor were a num- ber of mud-spattered cars—natives of the laboratories, some of them, and unnamed. They were specially built cars, sent out to search the future Mr. Kettering has talked about. From them, perhaps, will evolve the new type of car. “‘TT IS no conventional road that these cars travel,’’ Mr. Kettering told me. “The ordinary garage road test is any- fuel to run the cars. We must do all in our power to con- serve fuel by getting everything out of id _ Incidentally, talk- Ing about the con- servation of fuel, Mr. Kettering of- fered this opinion: Unless I’ lose my guess, within 10 years, all railroads wil be operating This odd-looking object is an en- gineer’s three-dimensional curve representing the explosions in a certain type of engine cylinder, expressed in terms of pressure, volume, and quantity it into a small black bottle of ethyl fluid. He placed the tip of the dropper where the engine could sniff the magic gas, and in a few more seconds it calmed down and ran quietly for a minute. Then the violent knocking indicated its ap- peal for more of the fluid. Next, a small quantity of the ethyl fluid was placed in the mixture of gasoline and kerosene, turning it red orange; and the engine now thing but scientific, but here at Dayton we hang thoroughly scientific research on the most grueling experiences out on the highway. The cars we use for our re- searches are kept out 24 hours a day. “A typical road circuit includes the best and the worst roads we can find around Dayton, over a circuitous route of 86 miles. The driver picks out the roughest hills, and all the ruts and bumps he can find. He drives the car hard and keeps it going, so that altogether it covers from 200 to 300 miles a day. ‘‘During this period the driver makes (Continued on page 148) Dic ap stn oats Rint ss CB

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38 Here is Epinard, the F “superhorse” from Me France, which has crossed the sea to meet America’s best e on strange baictle- ; grounds in a series of international races , we pe alee Lt 2 an By Stanley G. Zinke, M.D. BOUT a year ago a three-year-old A racehorse named Papyrus, re- garded as England’s best horse of that age after his victory in the famous Derby, was brought to this country to engage in an international match race with the best American three-year-old. Undoubtedly you will recall that Zev, the colt chosen to represent the United States, won the race handily at Belmont Park, N. Y. Probably you will recall also that there was some difference of opinion at the time as to whether Zev should have been selected to uphold the turf honors of this country in the international race, some racing experts holding that not Zev, but a colt named My Own, which had won every race of its three-year-old season, was America’s best three-year-old. Even after Zev’s victory over Papyrus, the con- troversy waxed warm, and to settle the matter, a match race was arranged be- tween Zev and My Own at POPULAR SCIENCE MONTHLY between atmosphere and man, I had occasion to study the racehorse in his native element for several months, watching his behavior under various atmospheric conditions. I found that one factor stood out—atmospheric pressure. The importance of atmos- pheric pressure—with regard to the physical condition of both man and beast—depends on the fact that the body must maintain a pressure of gases within the blood vessels ex- actly equal to the pressure exercised by the air. A dis- Heat causes pressure to increase; cold causes a decrease in pressure, and 80 temperature produces changes jn the body pressures. Humidity—moisture jp the atmosphere—likewise must be con- sidered. When there is little humidity the skin is dry, tough and unyielding, When humidity is great, the skin jg moist, soft, and elastic. These conditions have decidedly different effects on the extent to which the body will be affected by atmospheric pressure. Now, varying conditions of body pres. sures exert a profound influence on ordi- nary physiological processes. When the blood vessels are constricted or dilated, either too little or too much blood is Finish of the match race at Belmont Park, N. Y., between Papyrus, English Derby win- ner, and Zev, the pick of American three-year- olds, showing Zev winning handily. Zev’s turbance of this equilibrium stirs up trouble—if the pressure of the gases in the blood falls below that of the atmos- phere, the vessels will collapse or contract, and if it rises above that of the air, they will expand or dilate. iater defeat by the Kentucky colt, In Memo- Tiam, at Latonia was due, Doctor Zinke says, to the lower atmospheric pressure in Kentucky, to which Zev was unaccustomed admitted, and there is consequent dis turbance of the bodily functions. Weak- ness or exhaustion from too little blood is one extreme condition; congestion, inflammation, or rupture is the other. Now, let us see how all of this affected the three horses that contested Latonia, Ky. In this latter race a third horse—a Kentucky colt named In Memoriam, regarded as little more than a pacemaker—was an easy winner, defeating Zev by six lengths and My Own by 16. To racing experts it was one of the most extraordinary upsets of turf history. ANY excuses were made for Zev. Nobody, though, that I recall, suggested what I believe to be the real reason for In Memoriam’s victory, which was—weather. Few persons realize the extreme sensitiveness of racehorses to weather changes, and the effect of weather upon the condition of the track itself. I have yet to meet a racing ex- pert who recognizes the disturb- ing or stimulating effects of cer- tain weather conditions. In the course of my inves- tigations into the relationship Can Epinard Win in Kentucky? HE performances of Epinard, the four-year-old ‘*superhorse’’ from France, which is com- peting with America’s best in a series of interna- tional races, will be watched with increased interest in the light of Doctor Zinke’s remarkable theories regarding the effect of weather conditions on the physical efficiency of man and animal alike. Atmospheric conditions on the eastern seaboard of the United States, where Epinard has been train- ing, are very similar to those in France; therefore his acclimatization should be speedy, so far as the Atlantic coast is concerned. But will he be able to run at his best when he reaches the lower atmos- pheric pressure of the Kentucky mountains? Or will history repeat itself and will the great French horse succumb, like many an Eastern crack race- horse, to the onslaught of Kentucky thoroughbreds? Doctor Zinke speaks with the authority of an eminent physician and scientist who has made an exhaustive study of his subject. What he says is of revolutionary importance, not only because it opens up an entirely new phase of one of America’s most fascinating sports, but be- cause his discoveries may have a profound effect on human health and energy.—THE EDITOR. in the Kentucky match race’l mentioned. ON THE day of the race, pressure was low and fall- ing, temperature and humidity rising, and it rained lightly be- fore the race. The time of the race was slow, showing that the weather affected all three horses. The pressure at Latonia is nor- mally about .6 inch lower than that at sea level, the pressure under which Zev and My Own were accustomed to running. Against a Kentucky horse accus- tomed to a normally lower at- mospheric pressure than they, both of them were hopelessly handicapped before the start. A somewhat similar instance was the last Kentucky Derby. This was run on a much better day, but pressure once again was falling. The four leading horses, Black Gold, Chilhowee, B°v! Butler and Altawood, all 1.¢-e j Why the Fastest]R Changes in Atmosphere

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stiRacehorses Lose Produce Real Handicaps ere ASE; cold and go in the isture in be con- lumidity yielding, skin jg ditions on the affected dy pres- on ordi- hen the dilated, blood is aq no- nke in ned ant dis- Weak- e blood gestion, yther. — affected tested race’ e race, nd fall- umidity tly be- of the hat the horses. is nor- or than ressure y Own inning. » aCCUS- wer at- . they, elessly tart. istance Derby. better 1in was horses, Bev 1 vee horses that had been racing at Louisville, Ky, or had come down for the race from the more elevated territory about Lexington, where, of course, atmos- heric pressure is normally low. The yest that any Eastern horse could do in the Derby was fifth, and the time of the race was two seconds slower than the track record. N EVEN more startling example was a race at Latonia not long ago in which five horses contested—three fom Kentucky and two from the East. Though the Eastern horses— Martingale and Rialto—were high class colts and ap- peared to have the race between them, the three native entrants beat them by six or eight lengths, the difference, as I compute it, that the change of altitude makes between Eastern and Kentucky horses of the same class when they race together at the latter place. Race after race of this sort could be cited —and always with the same results. When Kentucky horses go to the sea- This remarkable photograph shows Black Gold leading by a length at the finish of the latt Kentucky Derby at Churchill Downs. level tracks of New York and Maryland, however, there is a different story to tell. Their efficiency—both speed and endur- ance—is increased temporarily; then they slacken up. This is because the blood of both men and animals living at high alti- tudes has a higher percentage of reserve oxygen than the blood of those living in the lowlands. Coming to a lower level, this reserve is pressed into service by the higher pressures, but it is eventually dis- Spated, and then the man or-animal has greater difficulty in sustaining the greater Weight of the air. In the pioneer days of our southwestern states the Indians would bring their staggy ponies down from the heights and walk away with the best horses the white settlers owned. In certain regions of South America, where racing is a favorite ‘port, the racing authorities have learned that lowland horses stand no chance with POPULAR SCIENCE MONTHLY a recently arrived high- lander. Consequently, they require that mountain horses must be at the tracks for days in advance of the events in which they are entered. There was an ex- ample of the temporary increase of efficiency that comes to a high- land horse visiting the sea level on the very same day that In Me- moriam was taking the measure of Zev and . My Own. The Kentucky colt, Beau Butler, defeated a field of crack two- year-olds at a Maryland track, winning a purse of more than $40,000 Again, justa short time before the Kentucky Derby of this year, we find a four-year-old Ken- tucky mare, Chacolet, making a jump down to Maryland and carrying off a purse of about the same size. Several weeks later, though, Chacolet failed dis- The four leading horses all were accustomed to Kentucky atmosphere, in which the best that any Eastern horse could do was fifth mally in the Suburban Handicap at Bel- mont Park, N. Y., due probably to the fact that she had remained at sea level beyond the time when her reserve supply of oxygen was available. During the entire month of August every year there is a race meeting held at Saratoga Springs, N. Y., in which the best of the Kentucky and Canadian horses meet the best of the Eastern stables for large purses. Eastern horses meet fre- quent defeat at this track from Kentucky and Canadian horses that they seem to outclass. Turf followers always have been at a loss to account for the many ‘“‘form reversals” of the Saratoga meeting, but I think we have the explanation in weather and climate—and particularly in atmospheric pressure. When horses that have been campaign- ing at the New York and Maryland tracks go to Saratoga, they go to a place of After winning the $10,000 Maryland Handi- cap last year, the Eastern three-year-old, My Own, lost to In Memoriam by 16 lengths in the higher altitude of Latonia, Ky. higher altitude. Kentuckians and Cana~- dians, on the other hand, descend from a higher altitude to a lower. This gives the Kentuckians and Canadians a marked advantage at the beginning, when it is that they score most of their victories. Later, though, the Eastern horses, im- proving in the higher altitude, come into their own and recoup the earlier misfor- tunes of their owners. | bape young children, young horses— those up to three years old—are ex- tremely sensitive to weather changes. Likewise finely trained horses—particu- larly those of fine breeding—are far more sensitive to changes than are less thor- oughly trained horses of poorer grade. Training is particularly severe on the younger horses. It removes fat, which is an insulator, a fuel, and a storehouse for nitrogen, the element upon which pressure depends. Young horses stand cold better than aged animals, because their heat-produc- ing qualities are better. Younger horses, because of the activity of their sweat glands, prefer drier air, while the older animals, with their tough, dry hides, appreciate humidity. Consequently you wiil find the younger horses performing best on cool, dry days and the older ones on warm, humid days, although both young and old do better under high pres- sure than low. Even on cool, dry days, however, and with a big advantage in weight, a young horse rarely will beat an older horse in the spring. The fact that the body of the younger horse is not yet attuned to the variable weather of the spring probably is the principal reason for this. So far as I know, even the most intelli- gent racegoers take scant notice of these highly important weather factors in estimating the chances of horses in the various races. Is it any wonder, then, that with the invisible influence of weather at work in addition to the factors that can be recognized, the number of persons who can win at the racing game is exceedingly small?

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Rebuilding the Portal that Moses ‘\IX huge pillars that are believed to S have supported the main archway to the throne-room of the ancient Egyptian palace through which Moses and Aaron passed on their mission of pro- test to the Pharaoh Merenptah against the captivity of the Israelites, have been brought to the Museum of the University of Pennsylvania. The portal will be reconstructed in its original form in a new wing of the museum, together with approximately 120 tons of additional material excavated by scientists of the university from the site of the ancient royal Egyptian city of Memphis. The photograph above shows workmen with block and tackle placing a section of POPULAR SCIENCE MONTHLY i one of the massive pillars on its founda- tion in the museum. Carvings on the block represent the Pharaoh threatening the Israelites held captive by him, but finally permitted to leave Egypt. All known data point to the fact that Merenptah was the Pharaoh of the Exodus. Each of the six stone pillars is 28 feet high and weighs five tons. The portal served as an archway in Merenptah’s greatest palace. This palace was ex- cavated at Memphis by Dr. Clarence S. Fisher, archeologist, after two years’ work at a cost of thousands of dollars. The building was constructed of massive walls of sun-dried brick, with columns and door-frames of limestone. Within Entered was a magnificent throne-room, which the Egyptian authorities have given to the university for reconstruction. The palace contained a great open court 80 feet wide and 175 feet long, surrounded by a colonnade of 34 columns. At each end of the court were state apart ments. The six columns above mentioned formed a vestibule to the throne-room and supported the roof. Archeologists be lieve it was in this room that the Pharaoh declined to yield to the pleas of Mose and Aaron until finally a plague came, killing the firstborn in every Egyptiat household. After the plague, he bade Moses and Aaron to lead the Israelites from Egypt.

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i” POPULAR SCIENCE MONTHLY 41 j which the n to the pen court rounded At each e apart- entioned yne-room ogists be- Pharaoh of Moses ue came, Egyptian he bade [sraelites Are There Twins in Your Family?! An expert answers questions so often asked about double birth, its causes - and hazards—Why some twins look alike while others differ— Why one twin is usually more vigorous than the other—Heredity and its influences By H. H. Newman, Ph.D. Doctor Newman its professor of zoology and embryology in the University of Chicago, and is a distinguished author- ity on the mysteries of multiple birth. The facts and theories that he presents here are based on his 16 years’ study of twins and twinning.—THE EDITOR. | \ ROM earliest times twins have been objects of unusual interest and curiosity, for there is real humor in the situation presented by the existence of two editions of the same person. Only last week I met avivacious woman, a duplicate twin so like her sister that even their most intimate friends could not tell them apart. Among other inci- dents of their interesting youth she told the following experience: The sister at one time had a most assiduous suitor, who came so often and stayed so late that she was not getting enough sleep. So she bribed her twin sister to entertain the young man on alternate evenings. The scheme worked perfectly until, on one of the evenings when the substitute was on duty, the suitor began to make invidious comparisons between the sisters, saying that he did not see how any one could ever think they were alike! This was too much for the young lady to stand and she confessed the whole plot. Even then the youth refused to believe in the deception ~~-and accused her of teasing him to test his sincerity. The final outcome of this episode was not related. [Ny HUMAN beings we recognize two dis- tinct ‘kinds of twins—duplicates and fraternals. Duplicate twins, such as the sisters I have mentioned, are technically known as monozygotic, which means that they are derived from one zygote or fertilized egg. Fraternal twins are known as dizygotic, for they come from two zygotes. Thus, fraternal twins are merely brothers and sisters who happen to be conceived and bornsimultaneously. Hence there is no reason to expect them to be more alike than are other brothers and sisters, except that they are of the same age and are likely to have more nearly identical experiences. Duplicate twins, on the contrary, have every reason to be alike, for they are biologically far more closely related than ordinary brothers and sisters. They really are two editions of the same indi- vidual. They begin life as a single egg, which develops for some time like any other egg, but later, for reasons that will be discussed, the embryo divides in such a way that the part that would normally produce the right side of a single indi- vidual forms a separate complete indi- vidual, and that destined to produce the left side similarly produces a separate individual. Thus it may be said without exaggera- tion that true duplicate twins represent Compare the two sides of this face of Douglas Fairbanks by covering first one half, then the other, with a sheet of paper. You will notice that while the two halves are very similar, there are certain distin- guishing marks, such as the depth of the scowl and the formation of the mouth and eyebrows. Apply the same test to your own face in the mirror. This difference in the sides of the face of any individual, says Doctor Newman, ex- plains why some twins, though really two editions of the same individual and thus very similar, do not look exactly alike a single person duplicated. The two are genetically as closely related as are the right and left halves of one’s own body. No wonder, then, that it is sometimes necessary to resort to ribbons of different colors in order to tell them apart! | Statistical studies of the degrees of resemblance between identical twins and | between the opposite sides of single in- * dividuals amply justify these statements. The coefficient of correlation in both cases is in excess of .9, which means that both are more than 90 per cent identical. In striking contrast with this is the fact © that fraternal twins, or ordinary brothers | and sisters, have, in both cases, a co-' efficient of correlation of only .5, which means that they are but 50 per cent identical. A STRANGE thing about twins is that quite com- monly they are reverse or mirror- image duplicates of each other, and not exact duplicates. By this is meant that the right side of one twin is often more like the left side of the other twin than like his own left side. Thus, if some one-sided peculiarity occurs on the right side of one twin, it is likely to appear on the left side of the other twin. Professor H. H. Wilder, of the Department of Zoology of Smith College, described a num- ber of cases in which the finger- print pattern of a given finger on the left hand of one twin was the mirror image not of that of his own right hand, but that of the right hand of the other twin. Furthermore, it not uncommonly hap- pens that one twin is right-handed and the other left-handed. In not a few cases it has been observed that the whirl of hair at the crown goes, clockwise in one twin and _ counter- clockwise in the other. This is one of the surest evidences that the two were once right and left sides of a single, individual. Sometimes it has happened that twins, taken at first glance to be duplicates, prove to be much less alike than one would expect. Are these to be classed as fraternal twins because they do not fulfill our expectations as to resemblance? Let us examine a parallel case. I look at my own face in a mirror and note that the two eyes are, in some respects, quite unlike. My two hands, especially in the details of the finger-prints, are ver} different. The shoe clerk tells me that’ one of my feet is about half a size larger than the other. My tailor finds difficulty in fitting me because one shoulder is broader and higher than the other. Look yourself over and see how dif- ferent your two halves, which are un:

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- wee “Alike as two peas”—Elsie and Ethel Howe, of Boston, Mass., are duplicates who have survived the hazards of twinning and are equally normal, healthy, and vigorous. Could you tell one from the other? Two younger brothers and a sister are triplets! questionably of monozygotic origin, really are. Why should you expect, then, that ‘two halves of a former individual that are now separate would be any more alike than two halves that have remained | together as parts of a single individual? HERE are, to be sure, many in- dividuals in whom the two sides are ‘remarkably alike. Parallelling this con- ‘dition of approximate identity are the instances of extremely close resemblance between twins. From the _ biological ypoint of view the two situations are jessentially the same. The life of twins before birth, whether they be monozygotic or dizygotic, is full of hazards. Statistics show that there is a high percentage of prenatal mortality in twin pregnancies. The reasons are not far to seex. The human uterus is ‘adapted for but one fetus at a time. When ‘two fetuses come to occupy the space normally occupied by one, there is certain to be crowding and keen competition for the available supply of nourish- POPULAR SCIENCE MONTHLY sides of the disk-like placenta, meet at the center and struggle for the neutral area. In the process of settling the dispute, it nearly always happens that blood vessels of the two individuals become united and the blood supplies of the two become intimately mingled. This would do no harm except for the fact that the give and take is likely to be more or less uneven. One may receive more blood in circulation than it gives back. When this disturbance of balance in the blood circulation is at all marked, one or both twins are sure to be more or less seriously dam- aged. The one that gets too much blood will be subject to dis- turbances, such as_ enlargement of the heart and distended blood vessels; while the one that has been robbed of its fair share, if the supply is seriously diminished, suffers from. partial or complete atrophy of the heart, diminution of the blood vessels and other se- rious disturbances incidental to in- vigor or general vitality. Twins, both of which are equally normal, healthy, ° and vigorous, may consider themselves unusually fortunate to have survived the hazards incidental to twinning without any untoward accidents. What causes twins? [* THE first place, it should be said that the tendency to produce twins, of both kinds, is hereditary and seems to be transmitted as often through the male line as through the female. What is inherited in the case of fraternal twinning appears to be merely a tendency for the two ovaries to become active at the same time instead of alternating in activities, as is the usual condition. The result is that at a given time each ovary produces a ripe egg and both become fertilized at the same time, thus producing two embryos. This seems intelligible enough, but the explanation of duplicate twinning is not so easy. What we are reasonably sure of is that this type of twinning is the re- sult of an early interruption in develop- ment, probably a failure for some days or weeks of the young embryo to attain a proper nutritive relation with the ma- ternal tissues. During this quiet period cooperation between the various parts of the embryo tment. It is partly on this account that twins, at birth, are commonly much smaller than single offspring }and are not as well nourished. There is a popular impression that one twin usually is stronger and more vigorous than the other. Almost every parent of duplicate twins will tell you that one of them seems to be the dominant member 4of the combination, to be noticeably the leader in most enterprises, to ‘be a little more vigorous and ‘healthy. In some cases the differ- 2nce in this respect appears to be Each of these duplicate twins shows evidence of being the reverse, cr mirror image of the other. Thus, on the twin at the left, the whirl of hair on the crown runs clockwise; on the twin at the right it runs counter-clockwise. This, says Doctor Newman, is one of the surest evidences that the two once were the right and left sides of one person seems to be retarded and there is a tendency for parts of the body to become independent. In this way the two sides cease to act as though they were integral parts of a single individual; each becomes in- dependent. The result is that when ,striking. As is not uncommonly she case, popular impressions have ,a sound scientific basis. Duplicate twins always have but "one placenta—the nutritive organ “connecting the fetus with the mother—between them, and there s always a keen contest between the twin . etuses for a share of this common organ. »The result is that the placental blood _ be sufficient to cause a noticeable differ- ‘vessels of the two, starting in at opposite Typical fraternal twins. They are no more alike than any other brother and sister, except that they happen to have been conceived and born simultaneously, and thus are likely to have more identical experiences throughout their lives. The boy has fair hair and blue eyes and is near-sighted, while the girl has brown eyes, dark hair, and good eyesight dividuals with an insufficiency of blood. Even a slight imbalance might readily ence between the twins in their relative normal nutritive relations are finally attained, the two half em- bryos develop independently and give rise to twoseparate individuals. oe HAT radio set shall I buy?” In next month’s issue an expert will answer this question for you, offering you impartial advice on the set that will give best results in your particular locali’y.

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Ith hy,” ves the ut hat of to ale ing the me ies, t is ices | at two the not > of Oop- s or na na- ion ryo ws ror vin the son POPULAR SCIENCE MONTHLY Do You Sleep Too Much? Six hours a night should be enough if you learn the right way to woo deep and restful slumber—Practical hints by a disinguished authority on how to increase your waking hours and so improve your health, happiness and efficiency By Donald A. Laird, Ph.D. HE one piece of advice that you probably have heard most often is —‘Get plenty of sleep!’’ Your parents undoubtedly began tell- ing you that—and enforcing their wishes —when you were a child. Later you heard it from your family doctor, from your teachers, from your employ- ers, your friends—in fact, Science shows, too, that there are good and bad times for sleeping; that the way you lie in bed has great bearing on the quality of sleep you enjoy; that by cul- tivating proper habits of sleep and sur- rounding yourself with conditions con- ducive to good sleep, you probably can reduce your sleeping time to six hours and yet awake refreshed, invigorated, and with no trace of the tired feeling that now may make rising in the morning so much of a task. Undoubtedly you understand the pur- pose and general nature of sleep. Every living thing seems to sleep. Plants grow by rhythms— from almost everybody who claimed to have your in- terests at heart. Eminent men when interviewed are fond of including some varia- tion of the ‘‘early to bed, early to rise’’ adage as part of the recipe for success. ie The implication in this familiar admonition, and the impression of the sleep ques- tion that you p:obably have retained from childhood, is that to try to get along with less than eight or nine hours’ sleep a day is only a little less harmful from a_ hygienic standpoint than a systematic course of poisoning would be; that to sleep the clock around every night is about the surest way there is of becom- ing “healthy, wealthy and wise,’ and, I suppose, happy. Of course, there are the Edisons, the Napoleons, the Humboldts, and the other great men, past and present, who accomplished most ex- traordinary things on only three or four hours’ sleep a night. Probably you assumed counts, Do You Hate to Get Up in the Morning? alternate periods of rest and activity—so do even the lowest forms of animal life. The single-cell amoeba pauses to rest. Mollusks have peri- ods of inactivity during which they sink deeper into the SO, it’s because you haven’t learned mud. how to sleep, declares Doctor Laird as the result of his researches as professor of psychology at Colgate University. “Tt isn’t how much sleep you get that it’s the kind of sleep. * he says; “* “You can coax deep, restful sleep by relaxing every muscle of your body— even your ear muscles. The way to relax is to sleep partly on your side and partly on your stomach. “Take a noon-day nap, if you can. You will find yourself able to cut three or four hours at least from your night’s sleep and still be stronger and more efficient mentally and physically.” OUR sleep, though, is highly complicated. Dur- ing sleep your pulse beats more slowly and more feebly than when you are awake. In fact, after you are asleep a few hours, it. is virtually im- possible for any one to de- tect your pulse with the fingers. Special apparatus must be used by scientists to take pulse records of persons who are serving as subjects in sleep investigations. Also, when you sleep, the flow of blood to your brain decreases markedly. Science can thank a Parisian beggar for its first knowledge of this fact. This man was injured in a street accident, and portions of his skull were that, being exceptional in so many other particulars, these f men probably were exceptional in their sleep requirementagg well. AS IT happen : er, recent scien- tific investigatiaa Bh@ws quite def- inately that the ti at idea that it is wise to get a of sleep has tha a matter of fact, many people i geualy get too much sleep and that too much sleep may be harmful, just as too muth food is. It shows, too, that, like food, the value of sleep to the body depends not on quantity but quality; that, though sleep may seem to be the most natural thing you do, there is an art of sleeping you can learn. The famous men! who slept little undoubtedly had mastered this art and had learned hoy to ¢xtract from a few hours of good, sound {sleep more physical benefit than many hl obtained from a full night of fitful, wakeful, light slumber. If you teach yourself to sleep deeply, you will find that six hours is enough for you, Doctor Laird’s experiments show. To cut down your sleeping time, stay up until a later hour and rise at your usual time broken away, leaving the brain exposed. Through this “window” scientists in the hospital were able to watch the blood stream ebb and flow as he slept and awoke. Upon the decrease of the blood flow to the-brain during sleep depend such famil- iar methods of wooing reluctant sleep as eating a little, or placing a hot water bag on the feet. In either case the stimulation of the blood flow elsewhere in the body tends to draw the blood away from the brain; hence, tends to produce sleep. If you find it hard to get out of bed in the morning, it is because you have not learned how to sleep. The “tired feeling” that makes arising at the call of the alarm clock so difficult would not disappear, as you imagine, were you able to disregard its summons, for the deep, restful sleep— the real restoring sleep that repairs weariness of body and mind—comes dur- ing the first hour or two after you go to bed. It is then that your muscles are (Continued on page 145)

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he oR eT Ta ah a eS Se + = : > te, ] 4a , something of precision, this POPULAR SCIENCE MONTHLY The Most Accurate Man in America Slicing an inch into ten thousand parts was too crude and clumsy for Maj. William E. Hoke—A dramatic story of inventive genius that gave to industry new standards of measurement for quantity production By Norman C. McLoud FEW split seconds—314, to be A precise—served to show me why Maj. William E. Hoke is known to his friends as ‘‘Old Precision,’”’ and to a larger circle as ‘‘the Most Accurate Man in America.” I had asked him for the exact time— stressing the ‘‘exact.” To furnish an answer fitting the specifications he swiftly consulted three watches, one on his left wrist and two becomes a definite unit of measurement. When Hoke talked of a millionth of an inch, my nearest grasp of the phrase was a gasp. As a step toward my educa- tion the Most Accurate Man abruptly snatched a hair—one of my own. “It would take 1000 fine hairs, ranged side by side, to cover a standard inch,”’ he told me. ‘‘ You have less than half an inch the World War, which is a story in itself, “When the war came, accuracy was a vital problem,” Hoke told me. “The armies needed equipment in quantities never before conceived. This equipment had to be made in widely scattered fac- tories. When assembled, the various parts had to fit. Each part had to be in- terchangeable with all other similar pieces. Everything had to be standardized.” from pockets. “Twelve fifty-six three-eighths,” he replied with the comfortable as- surance of one who knows whereof he speaks. ‘“I checked up with Arlington at twelve o’clock.” As if a bare statement might be construed to lack and master of accuracy flashed his radio log. An entry of the day showed the receipt of the Arlington time signal at noon, with this notation: ‘Watch 21% seconds slow. Touched regulator one quar- ter turn and set minute and second hands.” Time entries appeared on the log twice a day, with precise regularity, forming a complete diary of the watch, its performance and all adjustments. That is Hoke. Accuracy is his passion. It makes him a tireless critic of things as they are. Sometimes he is called a grouch because of says Major Hoke. fine needle, for instance. point exceedingly sharp, and so it is. But contrasted with the stinger of a bee it is not sharp at all. telegraph pole. Think of This the Next Time a Bee Stings You a AN still has a long journey before he reaches the precision of Nature,” “Take the case of the We consider its “Highly magnified, the point of a needle appears as ragged as the broken stem of a Under similar magnifica- tion the stinger of a bee is infinitely sharp; it approximates, I believe, the billionth of an inch, instead of the mere millionth with which we mortals are dealing. “Man 39 fineness. never has approximated such This standard came about through the creation of the Hoke precision __ gages. These, briefly, are blocks of highly polished steel of precise thickness, which can be fitted together for any desired measurements. The method of making these blocks is simplicity itself. HIS is the way it works,”’ he explained. **We put a man into a ma- chine-shop with nothing but a standard yard or meter, and he can make 36 blocks of identical length. Because of highly polished faces, these blocks fit together exactly, without loss in the form of intervening spaces. This close adherence is ac- complished by ‘wringing’ the blocks together—fitting them by means of a twist- ing motion that establishes perfect contact. “In fact, the smooth blocks, fitted face to face his habit of criticising. When you’ know him, though, his criticisms become merely a part of his struggle for accuracy. His three watches symbolize this struggle; his radio log gives it written expression. It was this passion for accuracy that enabled Hoke to give the world a new standard of refinement in measuring , length. Slicing an inch into 10,000 parts , appealed to him as crude and clumsy for , mechanics and science. Hoke wanted something finer—something that would *, enable the world to deal in fractions ex- , pressed in light rays. The task he set for himself was dividing _ the standard inch into a million parts and _: making them workable. .- cision gage was the result. Under the in- The Hoke pre- fluence of his gage a millionth of an inch left on your entire head. Suppose you took this single hair and split it lengthwise. Starting with a single filament having a diameter of one-thousandth of an inch, if you should cut it into one thousand strips, each strip would represent a millionth of an inch; a million of those strips would be needed to cover an inch of the surface of my desk here. The ordinary ‘splitting of a hair’ doesn’t mean much in comparison.” XACT measurement of each of the million strips has been made possible by light rays and the Hoke gage. The ac- curacy thus attained has been revolu- tionary. Some studious observers even insist that the millionth of an inch won with the wringing motion, become as a solid piece of steel, adhering so tightly that the combination will support a weight of a hundred pounds through ten- sile strength, without pulling apart! To separate them requires the twisting mo- tion by which they were joined. This perfection of contact reduces the error of waste space to less than a millionth of an inch! “When the workman has made his 36 blocks of identical \length, he tests their thickness by stacking them up alongside his standard yardsti¢k, using the wringing motion to produce} perfect contact be- tween blocks. Perhaps the comparison shows that the stack {is too high. This in- dicates that his unig are not the right size, so he planes o them. more from each of

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itself, arious be in- similar lained. a ma- meter, blocks in the spaces. 2 is ac- inging’ parison This in- POPULAR SCIENCE MONTHLY Major William E. Hoke demonstrating the marvelous adhesion of his steel block gages when wrung together with a twisting motion. Several thin measuring gages adhering to each other rest on the column to which “His method of making accurate com- parison with the standard yard is simple, too. He may find, during his work, that the 36 pieces form a stack so closely identical with the length of the yardstick that the eye can see no difference. To make sure on this point he has only to take a knife straight-edge and lay it across the top surfaces of the stack and the stick. If there is a difference, the unaided eye can detect a crack of light 1/10,000 of an inch in thickness.” The comparison afforded by the use of the knife straight-edge enables the man in the shop to produce 36 blocks, each of them ex- actly an inch in length. Then come the subdi- visions. “To get smaller units, he merely divides an inch into blocks a tenth of an inch in thickness,’ Hoke told me, ‘‘so that he has everything necessary to produce units of any dimension running into three dec- imals. ‘‘Suppose we take 12 standard inches and three standard tenths of an inch. This gives us a standard 12 3/10 inches in length. Then we make 100 identical blocks the combined length of which equals this standard. Each of these blocks necessarily is 123/1000 of an inch thick. “Such is the process followed in making the gages. The completed sets are of two types—one containing 34 gage blocks and Major Hoke is pointing with two larger adhering blocks held in his right hand. A pull of 100 pounds would be required to separate the larger blocks when they have been wrung together closely, so perfect is their contact the other containing 81 gage blocks. ‘*The smaller blocks in each set are approximately one tenth of an inch in thickness, differing from each other on a scale measured by 1/10,000 of an inch. “The next larger gages differ by a thousandth of an inch; larger sizes by tenths of an inch, and finally we have gages differing by a full inch. By fitting these blocks together, we can build up in any combination we may wish, simply wringing together the blocks required to make the desired total dimension. With gradations of a tenth of a thousandth of an inch, it is possible to create more than 100,000 gage sizes within 12 inches.” Taking outside measurements of a plug gage with a Hoke gage fitted with caliper jaws placed at the ends of the assembled block units Application of the gages to every-day shop measurements is merely a matter of building up the blocks to the re- quired lengths. The fine (Continued on page 151)

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Congressman Frank C. Sites, Democrat, of Harrisburg, Pa., isa watchmaker and jeweler by trade. Educated in the public schools, he learned the trade at EP OD aE the age of 18, and — eu followed it for 30 years. Elected in 1922, he was the first Democratic Congressman from his district since the Civil War In making paper, as in making laws, Thaddeus C. Sweet manages to keep things stirring. This photograph shows him at work in the paper factory of which he is president. Besides being Republican Congressman from New York, he has been in the paper-manu- facturing business ever since 1895 POPULAR SCIENCE MONTHLY Skilled Mechanics in Congress And What They Can Make and Mend Besides Laws John J. Casey, Demo- crat, of Wilkes-Barre, Pa., is one Congress- man who knows how to find leaks and fix them. He began’ working when he was eight years old, first in the coal mines of Pennsyl- vania, and later as a plumber and steamfit- ter. He always has been actively inter- ested in the trade- union movement, and was the first man to be elected to the House of Representatives on a straight labor ticket. During the World War he served as labor ad- visor to the Emergency Fleet Corporation Fifteen years as a locomotive en- gineer taught John G. Cooper, Republican, of Youngstown, Ohio, how to run on schedule. He has served in five Congresses While preparing for the University of Pennsylvania Law School and a legal career, Congressman Everett Kent, Democrat from Bangor, Pa., worked for a considerable period as a machinist, constructing hoisting machiner y- He was elected to the Sixty-Eighth Congress, winning a@ majority in all the three counties of his district

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ve en- ooper, stown, edule. sTeSses oe you ever examined the tongue of a fly? Did you know that the silky butter- fy’s wing is really covered with scales, or that the spines on strawberries are like big carpet tacks? Perhaps it will be news to learn that the tiny foot of a spider carries two miniature pock- et combs on its end and that a snail has a tongue which is a beautiful and complex succession of spines. These are but a few of the everyday marvels seen by Philip O. Gravelle of South Orange, N. J., to whom a phonograph record looks like a succession of mountainous ridges, a safety razor blade like a jagged sheet of boiler plate, and microscopic organisms a few thousandths of an inch in size like fierce deni- zens of the jungle. Mr. Gravelle is known officially as a photomicro- grapher. In simpler lan- guage, he sees and photo- graphs the invisible world with a scientific sight nearly 2,000 times as powerful as the unaided eye, by means of a microscope and either a still or motion picture camera. If an ordinary ant actually were increased the tumber of times Mr. Gra- velle can magnify it with the microscope it would become a frightful monster more POPULAR SCIENCE MONTHLY By Fritz Block manufacturing which could be solved in no other way. To give an idea of the exacting scientific work involved, one of the eight require- ments in the competition which resulted in Mr. Gravelle’s winning the Barnard Medal called for photographing the hairs . 47 He Photographs the Invisible t The story of Philip O. Gravelle, whose astonishing skill with micro- scope and camera has opened new eyes for industry—The beauti- ful tongue of the fly—The comb on the spider’s leg—What makes water look green—Why a dull razor blade ‘‘pulls” you often have seen the surface of a pretty woodland pool marred by a green scum. To you that means the water is stagnant, dead, and so you shun it. But do you know that actually it is teeming with life? ‘‘The scum is not dead. It is made of countless millions of single living cells that form a spiral network of green bands, giving the substance its color. Patches of green on the bottom of the pool are beautiful microscopic plants. Specks on the water so small as to pass un- noticed are really beautiful plant designs in varied fan- tastic shapes. Other minute spots that would seem. mo- tionless if you could see them, really are moving forward and backward like miniature submarines, push- ing aside debris much larger than themselves. ** TF you are out for a swim you pass on to a clear pool, one that lies limpid and green in the summer sun. The microscope shows that really you are swim- ming in a sea of animals, tiny globules which are gracefully revolving and giving the water its green- ish cast. The technical name of these creatures is volvox, and are what make the pool look green. The motion is due to tiny hairs a a 2 than 10 feet tall, approach- ing the size of an elephant. Mr. Gravelle’s skill in photographing _infinitesi- mally small objects has brought across the Atlantic for the first time one of the If you could look through the microscope with Philip O. Gravelle, you would discover an astonishing new world of tiny wonders. Mr. Gravelle’s skill in revealing and photographing this invisible world with scientific eyes nearly 2000 times as powerful as human eyes, has won for him the highest honors in his field of science—the Barnard Medal awarded by the London Photomicrographic Society. This photograph shows him in his laboratory, examining the millions of minute living organisms in a single drop of water through the lens of a powerful microscope called cilia. “If you pick up a sub- merged leaf and look at it closely you may find a few jelly-like specks on its sur- - _ face. Photomicrography reveals these to be a variety most recent of distinguished of animals known as roti- scientific awards—the Barnard Medal, on the tip of the tongue of a fly, and _ fers. Motion pictures of one of the specks presented to him by the London Photo- enlarging 1500 times a species of a show that actually it is a whole colony mictographic Society. He won the dis- minute aquatic plant known asadiatom, connected with a common center by tinction of being the first American to which is so small that it cannot be seen threads radiating like the spokes of a receive this honor over constestants en- by the naked eye. wheel. The colonies are continually in tered from all over the world. By placing the motion picture camera motion, folding and unfolding like the behind a battery of optical instruments petals of a flower. Their cilia vibrate THE science of photographing under the life motions of minute organisms _ rapidly, agitating the water and causing the microscope has been' practiced may be photographed and later shown food: particles to stream toward the minute for some time in such fields as pathology, on a screen—a vivid motion picture mouth of each rotifer and then to still bilogy and botany; but now, largely drama, magnified thousands of times. smaller jaws. through the efforts of Mr. Gravelle, its “The results of this work are closely “A fly’s tongue, so small that it can Uefulness has extended to another pur- linked with our daily lives,’ Mr. Grav- hardly be seen without a lens,'!makes a Dose, that of furnishing an additional elle told me. “The findings help to lead _ beautiful photograph, with dainty curved link between science and industry by to a better and clearer understanding of lines extending in loops from each side solving mysteries and difficulties of many of nature’s wonders. For instance, like a fine etching. A wasp’s wing is seen

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To our unaided eyes this group of fly’s needles. POPULAR SCIENCE MONTHLY any of them that protruded the slightest fraction of an inch above the rest. “My instruments revealed many valu- able facts about phonograph records and One maker could not find out The reason your razor blade pulls when dull is explained by the photomicrcgraphs below. The upper one shows the edge of an unused blade; the lower one reveals what frequent contact with a beard will do. Both are magnified 300 times eggs would appear as a speck so small as to be almost invisible. Highly magnified, the speck is seen to inciude score or more eggs in a cluster to be two separate wings bound together by a very fine series of hooks.” Fascinating as are these un- suspected marvels which nature conceals beyond our vision, I learned that they are only part of the story. ‘The other part has to do with its practical application in industry. “‘Microsecopic photographs of the invisible world have become an immense aid” he said, ‘‘for such purposes as choosing be- tween proposed new manufactur- ing methods, and in detecting faulty construction. “For example, I was called in by a manufacturer of razor blades who was puzzled by the statement of a competitor that shaving wore out a blade by turning over tiny edges at the cutting surface. By enlarging a new and a used blade 600 times, we found that repeated shaving with an unstropped blade nicked the edge, instead of turning it over. “In another case a manufacturer of textiles wanted a measurement of the nap of some velvet. No instrument was fine enough to do this. The photomicrograph wascalleduponand not only measured these tiny threads but showed up conspicuously The tiny foot of a spider, when magni- fied about 45 times, is seen to be equipped with sharp-toothed combs that explain its astonishing ability to climb steep surfaces A group of volvox, the tiny globe- The tongue of a fly, so small that your eyes hardly could see it, is revealed by the microscope to be a beautiful work of na- ture, with delicately curved lines extending in loops from each side, as shown above why his records would not stand up under continued use. By magnifying cross sections of faulty records 60 times the photomicrograph discovered a thin wall about a thousandth of an inch thick at every fourth revolution. This broke down and caused defects in the re- cords. “The trouble was traced to a damaged screw thread in the master machine. Now the sapphire needle used in the original record is examined for perfection before being used. The photomicrograph will show beforehand just how it will rest in the grooves, and thus prevent de- fects. ““While the application of photomicro- graphy is still in its infancy, its scope seems limitless. For example, the photomicrograph will prophesy the per- formance of an alloy by _ revealing its crystal structure. Extraordinary shaped creatures that make the water of a pool look green when millions of them revolve on its surface. They move by means of little hairs called cilia polishing and very high mag- nification are necessary to reveal the closely-knit crystals, so es to allow them to be photographed. The photomicrograph also will de- termine the covering quality of paints by measuring the fineness of their pigments, which in turn govern the oil absorption of the paint. The polishing or cutting powers of abrasives can be measured by ascertaining the exact microscopic size of the particles and sharpness of the grains. “In this connection a choice between two manufacturing pro- cesses was determined by a photomicrograph. A manufac- turer of files was uncertain whether to finish his product with a sand blast finish or by the use of a soft abrasive. The fact that the sand blast gave the ridges of the file the sharpest cutting surfaces was shown by a microscopic com- parison of samples of each process at a magnification of only 16 diameters. Thus by consulting the microscope the superiority of one process over another was predetermined.”’ So it is that Mr. Gravelle’s skill with the microscope and the camera is open- ing new eyes for industry. —— tetentnaee A photograph of the lateral grooves on a phonograph record, magnified 70 times. The litde furrow. that ordinarily seem so close together, appear wic siy veparated Pe ae ae

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globe- > water nillions They ed cilia zh mag- to reveal SO es to graphed. O will de- lality of fineness | in turn n of the * cutting can be ing the of the of the a choice ‘ing pro- by a nanufac- neertain uct with he use of that the 2s of the surfaces pic com- ess ata ameters. ‘cope the another kill with is open- PRIMARY STAR oO COMPARED IN SIZE POPULAR SCIENCE MONTHLY SCALE OF MILLIONS OF MILES 20 40 iV c™ TO OUR SUN: THE PL The smatier or secondary star is 12,500 times as bright as the sun and 139 times as massive, scientific measurements show New Wonders in Giant Twin Star Strange Flaming Balls of Gas Twelve Times Hotter than Molten Iron WO vast flaming balls of incan- Cescent gas 12 times hotter than molten iron—the smaller ball 12,500 times as bright as the sun and 2000 times the diameter and 8,000,000,000 times the volume of our earth—hurtling about each other in a colossal ellipse of 173,000,000 miles every two weeks at the amazing speed of 128 and 153 miles a minute respectively! To such a tremendous conception were the imaginations of astronomers sum- moned recently when the Dominion As- trophysical Observatory, Victoria, B. C., analyzed the light from B. D. 6° 1309, a star catalogued more than 60 years ago and visible to the keen, unaided eye. For the spectroscope—an instrument that breaks up starlight into the various colored lights that compose it—and —— Monster spectrographic reflector in the Dominion Observatory, Vic- toria, B. C., used in measuring and weighing the Plaskett twin stars Discovered by Dr. J. S. Plaskett mathematical analysis revealed that this barely perceptible gleam came from two stars, by long odds the brightest and most massive ever discovered. By means of the great 72-inch reflector of the Dominion Observatory, the diam- eters of these great twin stars, as well as their distance apart, have been measured. Each has been weighed. Their physical properties, temperature, and brightness have been determined. It has been found that they are three times as hot as our sun, and that their distance from our earth is at least 52 million billion miles! ‘TEN thousand years ago, centuries be- fore primitive man found his way upon the stage of history, thelight that only yesterday was analyzed started racing to the earth at the terrific speed of 186,000 miles a_ second. While history dawned and while empires and civil- izations waxed and waned, that light streaked tirelessly across the incon- ceivable immen- sity of interstellar space. If this giant twin star were inhab- ited and possessed astronomers, to- day they would be studying light from our earth which started on its cos- mic journey ages before the stones of Nineveh were laid. Stupendous as are the figures that have been cited to describe these twin giants, probably they far under- state the facts. For they are calcu- lated, with scien- tific caution, on the theory that the The combined mass of the Plaskett twin stars is equal to 139 suns orbit of the twin stars’ vast swing is in the line of our sight. If such is not the case the figures would be much larger. As the bodies have not been observed to eclips each other, probably their respectiv weights are at least 14 per cent greate than the figures mentioned, and thei velocities at least five per cent greater. HE next largest twin star known is V. Puppis, determined at Harvard Observatory, with a combined mass 33 times that of the sun. The combined masses of the monster pair determined at the Victoria Observatory are 139 times that of the sun, at the lowest estimate. It is not impossible that these stellar Titans no longer exist, except as a diffuse nebula, a great fire mist streaming across incredible millions of miles. For in bodies with such enormous masses the radiation or light pressure of the interior is nearly equal to the prodigious gravitational force that tends to contract them. So delicate is this balance that even a slight disturb- ance of it might release the prisoned energies within them in a mighty cata- clysm, exploding them across the black vastness of cosmie space.

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a ee ee ee fee Oe a ee A Beginning of afriendship. Uttering yapping sounds in imitation of a puppy, Mr. Girard extended his cupped hands to the chow, which came to look for the puppy By Gilbert Girard Mr. Girard is the “‘phonograph menagerie.’’ He supplies the bird and animal sounds for the records of many of the leading recording companies. He is the particular favorite of children all over the country, for he has made ‘‘bedtime records’’ of the best loved nursery stories and rhymes, and he makes the ani- mals in these stories speak their own language. He has made a serious study of the language and habits of these furred and feathered folk, and from his experience says any one with ordinary vocal powers can learn how to imitate them. In this article he tells just how you can emulate his_ remarkable powers of mimicry. F YOU are fond of birds and animals, I you can learn to talk to them in their own language. Friendliness and patience are all you need to make you an imitator of animal sounds, if you follow the scientific methods of the professional mimics who have made these sounds their special study. The shy but friendly robin in your back yard or that cheery busybody, the squirrel in the park, will respond to your comradely call and soon you will have a circle of furred and feathered friends. The first step.in learning mimicry is to watch the bird or animal as it gives its call. The position of the head usually will tell you whether the sound is made with a contracted or expanded throat. The head up and the neck stretched indi- cate an open throat and sound produced with exhalation. Animals whose language is guttural POPULAR SCIENCE MONTHLY Why the Animals J[ The mechanism of the throat and mouth with which it is possible to imitate the widely varied sounds of animals and hjrds almost invariably speak with lowered head. This means that to imitate their sounds you will contract:your throat and practise your imitation with an inhala- tion. The lion’s roar is an exception, be- cause he gets his guttural sound from the stomach and diaphragm as he exhales. After you have an animal’s “formula,” it is only a matter of practice for you to be able to answer him correctly. Do not be afraid of the sound of your own voice. ‘THe animal usually is puzzled by the sound of his own kind coming from the throat of a man. Your dog, for ex- ample, will be frightened by this power of yours to make sounds that indicate the Expert Tells How “In addressing monkeys or apes, friendly sounds must be accompanied by appropriate facial expressions,”” says Mr. Girard. This is how he appears while enjoying a friendly and mutually entertaining chat with a gorilla presence of another dog when none is in sight. But an ingratiating whine, such as he uses to win your attention, will re assure him and he will be overjoyed. The popular conception of the sound of the dog’s bark is a “bowwow.” Asa matter of fact, what the dog really says is “wow.” Toimitate the small dog’s “wow” successfully, first open your throat pas- sages, then pucker your mouth as in @ pout. Now, while your mouth is in this position, say “‘ou,”’ asin “‘you,” and as you do so snap your mouth open, saying “wow” until your mouth is wide open. In making the sound your tongue should lie flat on the bottom of your mouth, and your voice should be pitched at a high head tone. ie IMITATING a large dog, the pro- cedure is the same, except that you should sound a deep bass tone—a chest tone rather than a head tone. In this case the “ou” is a long, deep growl from the throat, like a snore. A study of the habits of animals will give you an understanding of the meaning of their various cries that will repay you generously. You have heard squirrels whistle many times, yet if you imitate that call while you are trying to coax 4 little fellow to take your offering of food, he will make for the treetops. For that whistle is the squirrel’s warning call. To invite a squirrel or chipmunk to luncheon in language he will understand, You Can 4]

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POPULAR SCIENCE MONTHLY ls {Understand Me an ¥Learn Secrets of Mimicry endly priate ‘his is y and zorilla e is in , such will re- od. und of As a says is ‘wow at pas- is in @ in this as you saying yen. In uld lie h, and a high 1e pro- at you 4 chest [In this y] from als will eaning ay you juirrels imitate coax @ f food, or that ll. unk to rstand, my ie i * ~ oh, The author, serving refreshments, discusses prohibition with a camel in the zoo. “An offer of food,” he says, “is the token of friendship all animals and birds readily understand. Feed them while you coax them to speak” make his own deep clucking sound by mapping the tongue against the back of the palate as you inhale. Then smack thelips rapidly. Repeat this persistently without moving and he probably will gow bold enough to take a nut out of your hand. THE purr is a friendly password to all " the cat species, from Tabby to the videat and tiger. This sound, varying in volume with the size of the animal, is amply inhalation and exhalation with a tttling of the palate that is little more thana subdued snore. Be sure that you do tot let the sound come from the throat in tehearsing the purr, for then your amicable greeting might be confused with a snarl. Itis popularly supposed.that a cat says oly “meow.” But listen to the rather staccato sound the cat makes in greeting you when you enter the house. Stroke it a litle and tell it just what a nice kitty it is. Immediately, you will observe a difference Nits “meow” when it tries to engage in ‘onversation with you. Of all animals the cat is one of the fasiest to imitate. The sound “me-ow” begins with a long drawn out “me” with the throat contracted. For the “ow” the throat is opened and the sound is thrown through the nasal passages, producing a tead tone. When the cat is pleased, the me-ow” is very soft. When it is hurt, the sound is loud and long drawn, with a Vy, open tone for the “ow.” 434“ To invite a squirrel or chipmunk to luncheon in language he will understand, make his own deep clucking sound by snapping the tongue against the back of the palate, as you inhale. Then smack the lips rapidly. Repeat this persistently without changing your position This cat was very much afraid of the camera. Only by making a soothing purr was Mr. Girard able to gain her confidence To imitate the spitting of the cat, first make a hissing, spitting sound by blowing through closed lips. Then, placing your tongue in the middle of your mouth and contracting the left cheek, force the air between your tongue and your right cheek at the back of your mouth. Let the sound escape between your teeth and cheek, producing a squeaking, squawking sound. Finally, if you tap rapidly on the side of your mouth and cheek with your hand, breaking in now and then with the spit- ting sound, you will have a realistic cat fight. An offer of food is the token of friend- ship all animals and birds understand. Feed them while you coax them to speak and they will lose their natural distrust. The curiosity of birds will draw them nearer and nearer to you. But, if you are carrying a walking stick, an umbrella, or anything else that may remotely resemble a gun, birds will remain at a safe distance and let you keep the food. LWAYS bear in mind that animals are subject to headaches, toothaches, dyspepsia and corns just as man is, and are affected with the same grouchy moods that accompany these ailments in human beings. Because an animal is crabbed and uncommunicative today does not justify us in assuming that he has a naturally mean disposition. Leave him alone and then try to make friends with him another day; you may find him a genial, responsive creature, after all. Imitating the sheep is good training for the beginner. Let the tongue relax at the bottom of the mouth. Then say “ba-a-a,” making it a throaty sound with exhalation and tapping the Adam’s apple gently. A somewhat similar sound is the cry of a calf. This plea for its mother’s atten- tion will sound to your ears like “um-bu- ur.” The first syllable is.a nasal sound made with closed mouth. For the second, the tongue and throat take the same posi- tion you used for the sheep’s “‘ba-a.” If you think a cow has no powers of deduc- tion, give this imitation of a calf’s distress signal and then bark like a dog giving chase. You will see every cow within hearing ready to charge a stone fence. MONG the animals that make their calls with contracted throats are the donkey and his cousin, the zebra. To mimic the zebra, contract the throat and vocal chords, sucking in the air to make a loud squeaking whistle. Repeat this about five times, not too rapidly, then give the sound of “haw” as you exhale. (Continued on page 150)

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pon eal eatin chia the Foe oo _ a ae el ee tat OB nae all mia am ae a et iy ae tlle het PE VS 52 New Uses for Photo-Telegraphy |} POPULAR SCIENCE MONTHLY Police Send Finger-Prints of Hunted Criminals by Wire By Newton Burke HEN engineers of the American Telephone & Telegraph Com- pany and the Western Electric Company recently perfected a practical, commercial method of transmitting pic- tures by wire, the process was acclaimed mostly for its value in the dissemination of news pictures. It was pointed out that A close-up view of the receiving apparatus, with the control in- struments in the background newspapers, when the pic- ture-transmitting stations were generally installed, need no longer wait for trains and ships to bring photographs of far-away happenings. The pictures would be available for publication almost as soon as reports of the events that they illustrated could be transmitted by means of the telegraph. A few weeks ago, however, another and more dramatic use was found for the new photo-transmitting process. It was dem- onstrated to be one of the most useful weapons ever put into the hands of the police for their war against the criminal. With the aid of telegraphed pictures, when a countrywide search is instituted for a criminal, the police of distant cities need not depend on a telegraphed “de- scription” of the fugitive. They can have a photograph of him immediately. More, they can have his finger-prints, specimens of his handwriting, or any other sort of identifying material that can be photo- graphed S A test of the value of the photo- transmitting process in tracking criminals, the New York police selected a finger-print from the files at Police Head- quarters, and telegraphed a photograph of itto Chicago. The transmission required about four minutes, and scarcely was it completed when the Chicago police tele- graphed back an identification of the man. Insofar as its first purpose—the trans- mission of news pictures—is concerned, the new process proved itself beyond question during the recent Republican and Democratic National Conventions at prints by wire. behind the little lighthouse. extreme right. the amplifier, Cleveland and New York respectively. Photographs of convention scenes, dele- gates, and candidates were available for newspaper reproduction in cities near the receiving stations at New York and Cleveland virtually as soon as the tele- graphed reports of the convention pro- ceedings were received. Many attempts have been made to transmit pictures by wire, and several different methods have been devised. This system is the first, though, that has proved practicable both technically and commercially. The method is so simple that a positive film, made from any photographic nega- tive, is suitable for transmission. The ap- paratus transmits a picture five by seven inches in a little less than five minutes, and the picture is received in such form that after the usual process of photo- The sending apparatus used in transmitting pictures and finger- The transparent film is under the cover shown Controls are in the panel at the The apparatus with the dials in the center is Left: Motor that is used for driving the film This picture of a young American Telephone & Telegraph Co. operator, sent from Cleveland to New York, illustrates with what fidelity a trans- mitted photograph can be reproduced graphic development, it is ready for repro. duction. Line drawings, handwriting and printing, provided it is not too small, also can be transmitted. ‘THE film is inserted in the transmitter by rolling it up in cylindrical form. During operation, a very small and ip. tense beam of light shines through the film onto a photoelectric cell within. The film is rotated at a uniform speed, and by means of a screw mechanism is caused to advance parallel to the axis of the cylin. der. The motion of the light relative to the cylinder consequently is the same as that of a phonograph needle relative to 4 cylindrical record. Thus, each minute portion of the picture affects the intensity of the light reaching the photoelectric cell, A photoelectric cell is a device the electrical conductivity of which varies according to the intensity of light directed upon it. In the photographic transmission process, the variation in the amount of light striking the sensitive surface of the cell, caused by the lights and shadows of the picture, gives rise to a current. Through the agency of a vacuum-tube amplifier and modulator, this current controls the tele phone line current. The most dramatic use to which the photo- transmitting apparatus has been put came when this finger-print of a criminal was sent by the New York police over the wire to Chicago. The transmission took four min- utes, and two minuteslater the Chicago police telegraphed back a correct identification At the receiving end an unexposed photographic film is rotated under a beam of light in a manner similar to that at the transmitting end. Both films rotate at ex- actly the same speed, and, by means of 4 new device known as a “‘light valve,” the impulses starting from the photoelectric cell at the transmitter, control the amount of light reaching the film at the receiver. The system has been demonstrated to be applicableto radio when atmospheric conditions are such that steadiness of transmission and freedom from intet- ference can be assured.

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Ly ‘OF repro. dwriting, 00 small, insmitter cal form. _ and in- ugh the hin. The 1, and by aused to he cylin- lative to Same as tive to a | minute intensity ctric cell, vice the h_ varies ensity of ;; Inthe smission mn in the king the the cell, hts and ire, gives Through lum-tube ator, this he tele- photo- t came as sent wire to ir min- 0 police ication nexposed ra beam at at the ate at ex- 2ans of a lve,” the oelectric » amount receiver. nstrated ospheri¢ liness of m_ inter- POPULAR SCIENCE MONTHLY 53 Keeping Abreast of Science What the Newest Discoveries Are Worth to You ern covered wagon, opening up trails to new countries, pushing the frontiers of civilization to new limits, ftting for habitation untrodden lands where Nature stands, a stubborn sentinel, repelling the advance of those who would wrest from her the territory where she always has reigned in completesupremacy. The amazing accomplish- ments by this present-day pioneer are typified in the work of the United States Reclamation Service, the ef- forts of which are dramatic- ally set forth in a survey re- cently completed by a com- mittee appointed by Secre- tary of the Interior Work. In 20 years, working in 15 Western states, with Wash- ington, Arizona, Texas, and Nebraska at the remote ends, the service has made habit- able and fertile more than 1,200,000 acres of desert lands, that now yield an annual crop value of be- tween $50,000,000 and $75,- 000,000. It has supplied home sites for more than half a million people. Only Maine, of all the New England states, can report a larger number of farms than those contained on these once arid lands. Flourishing communities, with all the activities of the typical American town, have sprung up in the sections that irrigation has _ reclaimed. More than 90 per cent of the settlers are native - born Americans; hardy, venture- Phy em covered science is the mod- from the fact that Its name is derived it stimulates the action of the natural kidneys. Doctor Abel has used it successfully on animals, but if the German scientists carry out their announced intentions, their experi- ments will mark the first use of the device on human beings. The artificial kidney may be described similar toxic states. most successful weapons ever given to medical science for treatment of disease. Rays from the Animals? IVING plants and animals are radio- active, sending forth rays like radium, according to a report made recently by Albert Nodon, French scientist. As proof he _ exhibited three photographic plates on some souls of the type that each of which were unmis- takable light impressions, caused, he asserted, by the rays emitted by a radioactive mineral, an insect, and a green leaf, which were placed on the emulsion side of the plates in a darkroom. A similar experiment in which a dead insect and a dead leaf were used resulted in no ray impressions on the plates. Monsieur Nodon offered as his conclusion that radio-activity is an inevit- able accompaniment of living processes, and stated that the strength of photographic impressions produced in ex- periments such as his are an accurate measure of vitality. Super-Generator N ELECTRIC generator capable of developing 15,000 volts of direct current —from four to five times more than any direct-current generator previously built— crossed the plains in the days of *49 and won the West to civilization. It is interesting that all of this work has been accom- plished at no expense to the Dr. John J. Abel of Johns Hopkins University, who has invented the mechanical kidney, a wonderful in- strurhent that will take the blood out of your body, clear it of im- purities. and return it to your veins again. This amazing new weapon of medical science is shown at the right American taxpayer. The in- itial funds of the Reclama- tion Service were supplied by the sale of public lands, while the products of the reclaimed lands and contributions from the states benefited have supported the service through the years. A Mechanical Kidney REMOVING every drop of blood from a human body, cleansing it of impuri- ties and then returning it to the circula- tion may seem like an impossibility, yet that is exactly what German scientists purpose to do, utilizing the “artificial kidney,” an amazing device invented by Dr. John J. Abel, professor of pharmacol- ogy at Johns Hopkins University. The “‘artificial kidney” was developed by Doctor Abel to be used in treating victims of bichloride-of-mercury poison- Ing, scarlet fever, acute nephritis, and as a sort of filter. One end is attached outside the body to an artery, and an- other connection is made to a_ vein. Thus the blood pas- ses through, and the impurities are strained out by tubes of a substance called ‘‘celliodin,”’ which, however, does not remove the vital cor- puscles and proteins. An extract called “hirudin,” obtained from Hungarian leeches, prevents the blood from clotting as it passes through. Doctor Abel was prevented from con- tinuing his early experiments with the apparatus when the war made it im- possible to obtain hirudin. If the artificial kidney is successfully used on human patients, it is likely to prove one of the recently was completed by S. R. Berg- man, consulting engineer of the General Electric Company at Schenectady, N. Y. This machine is expected to influence re- markably many phases of electrical work, notably radio broadcasting. At present long-distance broadcasting is accomplished by means of a rectified high-voltage alternating current, which produces ripples that affect the clearness of the transmission. But the use of direct current, supplied by generators of the new type, this defect will be eliminated.

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© Harris & Ewing By chemical analysis of lavas of the Hawai- POPULAR SCIENCE MONTHLY grows close to the ground, to become a regular tree. An experiment to bring this about is under way at the department’s plant in- troduction garden at Miami, Fla. The plan is to cross the cotton plant with a relative, a rare Hawaiian tree called Kokia Drynarioides. Inasmuch as there is only one tree of this species known to exist, the plan cannot be put into effect immediately; but the government ex. perts have succeeded in growing the trees from seeds obtained from the lone specimen in Hawaii, and are hopeful of eventual success. So future cotton plantations may become cotton “orchards” or “forests,” containing, instead of low shrubs, trees from 15 to 25 feet high, that will pro: duce larger and better crops, and possibly result in cheaper cotton for the con. sumer. ian volcanoes, Dr. Henry S. Washington, world famous expert on the chemistry of the earth’s crust, hopes to find some clue to the vast mysteries that lie beneath the Pacific Ocean. For example, there is the theory that the moon once was part of the earth and was pulled out of it millions of years ago, leaving a hole that became the bed of the Pacific. Another theory is that the continents really float on a semi-liquid layer, and that they slowly drift about, so that the earth’s appearance a million years from now will be vastly different from the earth as we know it. The lava, it is believed, holds the clue to these mysteries Are You An Only Child? HE only child usually is regarded with pity. He is likely to be “spoiled,” people say, to become selfish and to develop other undesirable traits as a result of parental indulgence, which the children of larger families do not receive. Now, though, comes Dr. Hor- nell Hart, of Iowa, to state that the only child, far from being an object of pity, is rather to be congratulated. After a study of the children of 600 families of Davenport, Ia., Doctor Hart 4 \ x Dr. David Lumsden of the U, S, Depart- ment of Agriculture, who has made the amazing discovery that when the twigs of trees, the bulbs of plants, or other plant parts are exposed to a small dose of ether vapor, the plants can be made to wake up out of their winter sleep and to grow as actively as they usually do in the spring announces that the only child is brainier, more energetic, kinder, more sincere and more honest than children who have many brothers and sisters. Doctor Hart’s conclusions as to brains and energy were ar- rived at as a result of scientific tests; others are offered as the testimony of school authorities. Meanwhile Professor H. D. Fish, of the University of Pittsburgh, supplies some highly interesting facts relative to heredity and the birth rate, the result of a study of more than 2500 families. If the second child is a girl, states Professor Fish, it will be born, on the average, 3.26 months later than if it is a boy, this being true no matter what the sex of the first child. This difference in the time of birth probably is sufficient to explain the interesting fact that more boys are born than girls. Also, Professor Fish reports, the firstborn is more likely to be a boy than any of the later children. If the parents are of different national- ities, Professor Fish finds, the chances are much greater that most of the children will be boys than if the parents are of the same stock. However a 20-year study of births and parentage, states Professor Fish, indicates that the preponderance of male children over female is slowly becom- ing less. ‘*Forests’’ of Cotton Trees? OTTON is due for a great rise, if plans of the Department of Agricul- ture are successful—not in price, however, for the department is merely seeking to persuade the cotton plant, which now This apparatus, constructed by J. P. Ault of the Mag- netic Laboratory of the Carnegie Institution, is the last word of science in the exact measurement of the earth’s magnetic intensity. Variations in the earth’s magnetism, it is believed, are responsible for many difficulties in radio transmission, as well as for the ‘‘magnetic storms” that occasionally play havoc with telephone and tele- graph lines. causes these variations, it may be possible to predict radio conditions in advance, just as weather is predicted If science can succeed in discovering what Worthy of Honor CIENCE knows no boundaries. It is not remarkable, then, that the Franklin Institute of Philadelphia, in conferring the Franklin medal this year, should have chosen Sir Ernest Rutherford, eminent British scien- tist, as the recipient of this, its most dis- tinguished honor. The medal is conferred upon Sir Ernest in recognition of his researches in physics. He probably is the world’s leading worker in this branch of science. Indeed, a distinguished scientist has said: ‘‘When some eminent men publish an experiment we say, ‘This is very interest- ing; we must repeat it to see whether it is true.’ But when Rutherford publishes an experiment all say, ‘This is true; we need not repeat it’.’’ international Bese come oe ORR tees oe tan ee ee aS

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become 4 about jg Plant in- ‘la. The it with a Pe called | aS there Known to nto effect nent ex. ving the the lone opeful of nS may forests,” bs, trees will pro: Possibly the con. Mag- ie last arth’s etism, ies in rms” tele- what radio licted ational rkable, ute of ranklin sen Sir 1 scien- ost dis- on s«Sir ches in world’s cience, s said: lish an terest- er it is blishes le; we PREFERENCES ~ AA. Mechanical Sig Santee w ey eee 2rike + ke Ce ; BB. Shelters ete. We : CC. Waler inlet Cages % .D. Divistons of Sechions”™ - ‘LE. Pump Motor Houses? Pumps PSF Seana tearely Spreuas. ss ie ba) thie SS i pe This drawing shows in detail the construc- tion of the mammoth Southampton floating ~ drydock and its method of operation in »~ lifting a great ocean liner. Lettered parts are explained in the legend at the left of the illustration and in the accompanying article a ae Above is a photograph of the completed dry- dock, with a capacity of 60,000 tons. The steamship Aquitania is seen at the left. The picture in the circle shows the floor of the dock with keel blocks and bilge blocks in position, ready for an incoming vessel The Largest Floating Drydock in the World By S. W. Clatworthy HEN the Prince of Wales for- mally opened the largest floating drydock in the world recently at Southampton, England, that port made a bid to become the world’s leading haven for the greatest ocean liners. Pre- viously liners of the size of the Majestic and Leviathan were compelled to go for tepairs to Hamburg or to Boston. Lifting the 52,000-ton steamer Majestic will be a comparatively simple procedure In the new dock, since it has a lifting Power of 60,000 tons. Built on the sec- Uonal plan, it can be enlarged at will by the addition of another section. The over-all length of the dock at pres- ent is 960 feet; width 170 feet, and height more than 70 feet. In its construction about 3,250,000 rivets were placed. When the dock is to be submerged to receive a vessel, water is admitted into compartments through special inlet pipes equipped with valves operated by hand and by an electropneumatic control sys- tem. Indicators show the depth of water in the various compartments. The 14 main pump motors for ejecting water and thus lifting a ship are arranged so that there is one motor for each section. These motors are controlled by a press- button system from the valve house. A complete telephone system connects the valve house with each of the motor houses. Because of the great weight of ships to be lifted, the blocks and supports are of unusual strength. On a_ continuous timber base running along the center of the dock are cast steel wedge blocks sur~ mounted by a timber block. The bilges of . a vessel are supported by timber blocks with steel bases. These are made adjust- able to any ship. A ship is centered automatically by four electrically driven side shores, arranged so that opposite pairs are geared together and driven by one motor. On each side wall is a three-ton warping capstan. The dock is connected with the shore by four mooring booms 110 feet long, anchored to reinforced concrete dolphins. The electric-lighting system is designed so that the light may be concentrated on any part of the dock or ship.

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fai tag aes Mee ie Pee ; ae te ee ce ee al OP eden, oe —-_ ee Thomas Wilfred, inventor of the “color organ,”’ at the keyboard of his instrument By M. Luckiesh VERYBODY knows that music has EL the power to stimulate or to de- press. No knowledge of music is needed for a person to react quite differ- ently to a grandiose, martial air, a lively dance tune, a dreamy waltz, a senti- mental song, or a funeral dirge. Light and color have similar powers, although these effects have not been built generally upon definite, standardized principles. Adequate controllable arti- ficial light did not become available until recently, so that the development of the use of the powers of light barely has be- gun in earnest, even among those who appreciate its possibilities. Most persons recognize, although vaguely, effects of light somewhat analo- gous to those of music, but, of course, the two are not related simply, as some people assume them to be. Who has not re- sponded to the cheerfulness of a bright sunny morning and has not felt its stimu- lating influence all day long? On the other hand, POPULAR SCIENCE MONTHLY Lights as an Aid New and Useful Secrets of Colored Lights Depress and Cheer, One of the striking light effects pro- duced by the color organ appears below play their parts as definitely as do flesh and blood actors. realisms to the sparkling, colorfy| lighting effects of fanciful Settings and unreal worlds is agamut of powers of light. theaters, dining-rooms of hotels, ball. rooms, are beginning to utilize the powers of light. It is true that onlya beginning has been made because, ag in the case of music, we must not only learn how to “ play”’ light, but its ren. dition must not proceed too far be yond public appreciation. This new art and science of lighting has not entered the home to any From such Even the auditoriums of extent, in spite of the fact that the fixture gives direct, indirect, and semi-indirect light, simultaneously, by means of an in- verted, semi-transparent shade with an open- ing at the bottom. The wall boxes produce indirect light of three tints. The artificial win- dow at the rear provides sunlight, moonlight, and sunset effects on the painted background who has not felt the de- pression of an_ overcast, shadowless day? The great symphonies of the sunset hold us enrap- What the Colors Hold for You HE little chart repro- duced here was prepared tured as we witness this benediction of the day. From the _ ever-changing lighting of a landscape we sense the parade of moods. The play of light from stained-glass windows of a cathedral breathes life into the restful scene. The delicate fire of the opal and the restless sparkle of the diamond are examples of melodies of light. On a large scale we have fire- works making their appeal in a more primitive manner, but still by the powers of light. In the theater, light has been used to produce differ- ent moods. The meager, colorless light of the prison, the brilliant sunlight, and the pale light of the moon by Mr. Luckiesh to indicate at a glance the general effects of various colored light upon our mental and physical con- dition. It is based on his ex- perience as Director of the Lighting Research Labora- tory, National Lamp Works of the General Electric Co. Study it for a moment. Doesn't it define for you, for the first time, some of the vague feelings you have had about colors and their effect Blue-Green upon your moods? And doesn’t it suggest surprising possibilities for lighting the rooms of your home? Indeed, you will find that this simple chart, combined with Mr. Luckiesh’s forward-looking story, is a wonderfully lucid introduc- tion to a new science fraught with tremendous possibilities. Mr. Luckiesh attempts merely to suggest some of these possi- bilities. He points out how the scientific arrangement of light and color effects not only will beautify our homes, but will bring us rest, contentment, health, and energy. In short, he shows us how, by using color effects for our benefit, we can copy what Nature always has done to make the world a delightful place to live in —Tue Eprtor. introduction of variety inte our homes is very desirable. Most persons light their homes merely with the idea of extending the “day” somewhat. They seem to think merely in terms of obtaining sufficient illumi- nation for reading and other activities. They do not realize that artificial light can introduce beauty, charm, cheerfulness, rest- fulness, coolness, warmth, and other possibilities. The mobility of light renders it a medium much superior to paints, wall-papers, furnish- ings, and the other “fixed” media that have reigned supreme. Light has power to make a house a home. The psychological and physiological effects of color cannot be presented in de tail in a brief article and there are so many ramifica- tions that it is dangerous to

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id lored heer, ly as do ‘om such colorful Settings of powers riums of els, ball. ‘ilize the at only a cause, ag not only t its ren. > far be ‘lighting / to any that the luce wine ght, und ety into esirable. it their the idea “ day” seem to erms of illumi- id other do not al light beauty, s, rest- varmth, es. The ders it a prior to furnish- ‘*fixed” reigned ‘0 make al and of color | in de cle and amifica- rous to POPULAR SCIENCE MONTHLY to Your Happiness Illumination in the Home—How Subdue and Stimulate You present anything more than generaliza- tions. However, with this caution, the circular chart at the bottom of page 56 js presented to show the general effects of yarious colors upon us. The colors of the spectrum are placed in proper sequence around three-fourths of a circle, the remaining quadrant being given over to colors that may be called ‘‘purple.”” In modulating from violet to red we begin with violet-purple, and pass through purple, and finally reddish purple. This color circle may be divided ap- Red, green, and blue lamps are concealed above the skylight of this dining-room. By blending these colored lights in various amounts, through the use of electric switches or rheostats, any tint of lighting may be ob- tained. Thus the family may dine in artificial sunlight, moonlight, or the rose color of dawn, as they desire proximately into three parts in which the colors have certain characteristics that classify them respectively as stimulating, tranquilizing, and subduing. On the outer rim a further subdivision is attempted. At opposite ends of any diameter com- plementary colors are found. Colored light is very much more power- ful than colored pigments. It tinges everything, while a colored vase, for ex- ample, extends its influence barely be- yond its boundaries. We must take this into account if we are to be successful in Producing desired lighting effects. A green vase may be just the proper note to complete a color-scheme, but a green light, if it illuminates the faces of our companions, may become very displeas- ing. Some colored lights should be con- fined to walls and ceilings, and they should be drowned out by warm light localized on the faces in the room. - We may have fairly neutral walls and ceilings in our homes, obtaining our color notes from furnishings. Then from hid- den sources of light in fixtures, ornaments, wall-boxes, and architectural details we can make this wonderful medium—light —-spring forth by pressing switches. In general, it is well to confine the use of deeply colored light to secondary lighting. For ex- ample, in the dining-room we should have white light on the table and a light of a warm tint on the faces of the diners. This can be achieved by any pendent shades tinted a warm yel- low-orange. The strongly tinted light may be confined to ceiling and upper walls. F A stimulating effect is desired, orange-red light may be emitted upward by a suspended bowl, by **flower-boxes”’ on the walls, or by large vases. A ‘‘cool” effect suggesting the out- doors can be obtained by using blue-green lamps or colored accessories con- cealed as suggested. Colored gelatines and colored glass accessories are available for this purpose. The “‘day- light”’ lamp also has possi- bilities when used in con- trast with “‘warm”’ light. Most of the foregoing color effects are not to be lived with constantly. Va- riety always emancipates us from the monotony of fixed decorative schemes. Portable lamps will be found valuable allies in in- troducing variety in lighting. Those who have not ex- perimented with the possi- bilities of light will find that light of the tint of the candle-flame is kind to human beings and to faded surround- ings. It provides a glow that can be lived with, for it is consistent with our uncon- scious demand that the home be a place of comfort, protection, and cheerfulness. With growing experience and under- standing, man is going to demand more mobile light. He will want the light sym- phonies of outdoors brought indoors. He will want the charming melody of the opal and the brilliant light-music of the diamond reproduced by artificial light on a large scale. He is going to develop an “eye” for subtle effects of light, just as he has developed an “‘ear” for modulations of music. e- - has made only a beginning. §7 In the applica- tion of the pow- ers of invisible radiation, science Above is one of the latest developments in the use of the X-ray—a water-cooled, high voltage tube for the treatment of deep-seated can- cer. Itis the work of Dr. W. D. Coolidge, of the General Electric Company, who is seen in the picture with his apparatus Some day we are going to have marve- lous jewels of light and super-decorative schemes of light before which the decor- ator’s effort today will be somber and feeble indeed. The lighting artist will be a super-decorator and a super-doctor in this new era. Then there are other important fields for usefulness of light and its attendant radiations. For example, colored lights have certain chemical, biological, or therapeutic effects when applied to the body. But this phase of radiant energy from the sun or artificial sources is not confined to visible rays or colored lights. Radiant energy of shorter wave lengths, known as “‘ultraviolet radiation,” is per- forming great services in such fields as the killing of bacteria and the prevention and cure of rickets. r HAS long been known that there is a seasonal variation in the prevalence and seriousness of rickets. In winter, when there is much less daylight, many infants show signs of the disorder, the floodtide being reached at the end of March. Ultraviolet radiation is found to be protective against this ailment. Réntgen or X-rays of shorter wave length also are curing many diseased conditions. Then comes radium with its still shorter and mare penetrating radia- tion. Miraculcus cures are achieved. Tumorous growths and cancerous condi- tions, lying deep beyond the reach and skill of the surgeon’s knife, are conquered by radium rays that pass through the normal tissues without permanent harm. It is certain that only the feeblest be- ginnings have been made in the applica- tion of invisible radiation, extending from the visible region through the ultraviolet and X-ray regions and into that realm of (Continued on page 153)

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; # & : said to be the lightest plane for its horse- ke al it ns Paes a le te am eee POPULAR SCIENCE MONTHLY ‘ World’s Smallest Plane Has 18-Foot Spread HE world’s smallest airplane, chris- tened the “‘ Fly,” is the prized posses- i sion of the Army Aviation Corps at ‘Kelly Field, Tex. Though the wing ‘spread is only 18 feet, it develops a speed -of 115 miles an hour. The machine is equipped with a three- cylinder motor of 69 horsepower. It is of the radial type. The cruising radius of the plane is 500 miles and sufficient fuel can be carried for four hours’ flying at full speed, or 514 at cruising speed. The plane stands no higher than a man. Lieutenant D. Phillips, one of the army’s pilots, is shown standing beside the midget at Kelly Field. New Navy Plane Does the Work of Three ‘A SEA and land plane combining the functions of three planes of the usual ) types has been developed by the Bureau é /of Aeronautics of the Navy Department sin collaboration with the American air- ‘craft industry. The plane, known as the /“CS,” is designed for bombing, torpedo launching, and long-range scouting. It is ; power ever built. ; Another important feature is that it is sable to fly with more than its own weight eas a load. In fact, tests have shown that with its single engine it is able to carry a greater load than the twin-engined bombers that have been in use for the + past few years. The CS plane is powered with a , Wright T-2 engine of 650 horsepower. It is quickly convertible from a seaplane into a landplane, or vice versa. The weight of the machine is about 4000 pounds. Its wing spread is 56 feet, its height 11 feet, and its length 34 feet. Fully loaded for a long flight, the CS carries 15 barrels of gasoline and one barrel of lubricating oil. It has a range of about 2200 miles, without landing and without refueling. Its landing speed is 55 miles an hour and as a landplane its maximum speed is 105 miles an hour. The construction is of steel and duralu- min except for the wings, which are made of wood and fabric, and are so designed that they can fold back, thus effecting a marked saving in space. This plane is also designed so that it can be launched from a catapult on the deck of a battle- ship. Included in the equipment is a radio set for both sending and receiving, two machine guns, and lights for night flying. Thirty-five of the new machines have been ordered for the navy. % = a ee 8 ._ : es « = a ae The new navy “‘three-in-one”’ plane during test flight at Anacostia, D. C. New Mooring Mast Supplies Helium to Dirigibles i ALLOW dirigibles to “gas up” - with non-inflammable helium gas. a helium-bearing mooring mast has been erected at the new government helium plant at Fort Worth, Tex. Up the center of the mast, which is 173 feet high, a large hollow steel pipe will deliver the helium gas into the body of dirigibles. The mooring mast is located in the center of one of the most important helium deposits in the United States, in the north-central part of Texas. Here the safety gas is being produced in such increasing quantities that the cost js steadily decreasing. Helium mooring mast at Fort Worth, Tex. Amphibian Planes for Army Designed by Loening HE United States Army Air Service has contracted for the construction of 10 amphibian planes of an entirely new type designed by Grover C. Loening, president of the Aeronautical Chamber of Commerce and inventor of the flying boat, according to a recent announcement by Maj.-Gen. Mason M. Patrick, chief of the service. The new design ‘is said to represent the first successful flying boat that is com- pletely amphibious, operating on land and water. In secret tests its perform- ances are reported to have compared favorably in climbing and maneuvering ability with land type airplanes of equal weight and power. It has attained a speed of about 120 miles an hour. The hull of the plane is metal covered, and metal is used largely in the construc- tion of the wings. For service as a sea- plane, the ship is equipped with pontoons. The landing gear, folded up underneath and at the side of the hull, is released when the pilot presses a button on the dash- board. A feature of the design is the installa- tion of the inverted Liberty motor, re cently developed. This arrangement, in which the cylinder heads are at the bot- tom of the motor, puts the propeller hub at the top instead of the bottom, and as a result the motor is said to operate more effectively, while the oiling system 1s greatly simplified. — 35 + rp a: a Gee Ln ne a Of ae [6a oe [6emte Se 3 Ge

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ex. my rvice tion new ning, er of oat, t by of of t the com- land orm- yared ering qual ed a ered, truc- sea- oONs. eath when Jash- talla- 1t, in bot- - hub las a more m is HERE can be no This apparatus breaks up whirls and eddies in the air flow POPULAR SCIENCE MONTHLY Flying Made Safer by Wind-Tunnel Tests aie Be guesswork in de- signing and construct- ing an airplane. The airplane must be per- fect before it takes the air; otherwise it may be wrecked and lives may be lost. Yet the airplane designer has not the same chance as an automobile or ma- rine engineer to make safe tests of his craft under actual operating conditions after it is assembled. How to make certain that an untried air- plane—particularly one of new design—is safe and practicable before it is subjected to a test Below is the exhaust fan that sucks the air through the tunnel, in imitation of the action of wind, which is caused when air rushes into cavities in the atmosphere 59 This balancing apparatus below the tunnel, sup- ports the model airplane A model plane, 1/24 the size of an actual plane, on the bal- ance in the wind tunnel at McCook Field, where mod- els are tested for stability and strength to take the guesswork out of airplane con- struction. The balance supports the model approx- imately as the air would in flight, while the midget plane is subjected to all kinds of wind conditions of actual flying always has puzzled aviation engineers. The problem, however, has come closer to solution than ever before by the recent construction at McCook Field, Dayton, Ohio, of a “‘ wind tunnel,”’ in which minia- ture airplanes, exact scale models of the larger planes to be built, are subjected to precisely the same air strains that the real planes will encounter in actual flying. In every particular save wires and fit- tings the tiny planes—their greatest dimension is about 20 inches—are identi- cal with the larger craft they represent. They have cockpits, propellers, rudders, windshields; there are even little knobs placed in them to represent the heads of the occupants. The thin portions usually are made of metal, the rest of maple or ‘ome other close-grained wood that will lot warp. In ordinary pattern making, an error of 1/100 of an inch is admissible. These models must be accurate to 1/200. The wind tunnel is five feet in diameter. Air may be drawn through it at any de- sired velocity by means of an exhaust fan. The model is placed in the ‘‘experimental chamber” in the center, and is supported Y suitable balances, so that the forces taused by the moving air can be mea- sured. These balances, placed outside the air sream, are so delicate that air forces canbe determined to within 1/10,000 of a pound. Testing in the air tunnel is the last step in designing an airplane. That is to say, the model is not constructed first, but is prepared from the plans drawn for the actual plane after all engineering calcula- tions have been made. The tests are valuable for determining Map of Salton Sea Made from 2000 Photos . HE hazardous work of mapping the Salton Sea in southern California from an altitude of nearly 15,000 feet recently was com- balance and stability. If the model passes the tests, it may be assumed that the de- sign for the actual plane is correct. If the model fails to pass, the actual plane is not constructed and thus money is saved and life safeguarded. U.S. Helicopters in Contest F THE 19 entries for the British Air Ministry’s helicopter competition for a prize of £50,000, the United States heads the list with nine different ma- chines. Great Britain is second with four, while France, Belgium, and Italy each have entered one. Tests of the machines began August 1 at the British government’s aircraft center at Farnborough. To win the prize, a machine is required to make a straight up-and-down flight, attaining an altitude of 2000 feet, a hovering flight of half an hour, a circular flight of 20 miles at 60 miles an hour, and a descent into a small area from 330 feet with the engine stopped. Such a per- formance never has been approached. the pilots and photographers suffered from the extreme cold of the high altitude, even in extra heavy flying suits. pleted by fliers of the United States Army Air Service. In planes espe- cially equipped for the purpose, the aviators took 2000 different photo- graphs. After the negatives had been developed and printed, the prints were matched painstakingly to- gether to form a complete map of the district. During the work Matching the photographs together to form the map of Salton Sea ' )

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. POPULAR SCIENCE MONTHLY Racehorse Flies from France to Holland FRENCH yearling colt owned by an attaché of the Dutch legation in Paris holds the distinction of being the first racehorse ever shipped by airplane from one country to another. The colt was transported from Paris to the owner’s farm in Holland on a plane of the French The Most Valuable Eg¢ ‘THE most valued egg in the world is that of the great auk, a bird that abounded in the regions of the once North Atlantic, but that is now extinct. The last auk egg sold brought a price of about $2500 The auk was a diving bird, about the size of a duck, but was unable to fly because of its small wings. It laid one egg at a time. The birds and their eggs were used largely for food among sea- faring folk. So many of them were killed that the species has entirely disappeared. Air Union especially fitted with an aerial horse stall. On the journey through the skies the colt was accompanied by a stable boy to care for it on the way. Three other passengers interested in the experiment traveled in the same plane. The photograph shows the colt being transferred from a wagon to its stall in the body of the airplane. Electric Shock Warns Fish N ELECTRICAL method of saving fish from death in the irrigation canals of the West has been invented by an engineer of the General Electric Com- pany. It consists simply of warning the fish to “keep out” by giving them an electric shock. This is done by the use of electrodes immersed in the canal, with electric currert flowing into them. It has been discovered that the re- sistance to electricity is greater in water than in the body of a fish, and that if a fish swims in the vicinity of two or more electrodes, it receives a shock that causes it instinctively to dart away. In the past, mechanical devices such as screens were employed unsuccessfully. Suggestion Boxes Invite Ideas of Employees T° PROVE to employees that there ig money in ideas, and to encourage cooperation in improving working cop. ditions and workmanship, a large elec. trical corporation at Schenectady, N. a recently installed boxes in various parts of the large plant where employees may deposit helpful suggestions. The contributions are examined by a suggestion committee, and for the ideas that are accepted the contributor receives a cash award. During the first year that this plan was tried out 908 suggestions for im- provements in accomplishing certain processes, in ease of handling material, and conservation of waste, were accepted and $15,095 was paid out as prizes. The plan proved so successful that it js now a feature of the plant. Placing a suggestion in the se box Butterflies and Liquor RECENT experiments by a British zodlogist have led to the discovery that male butterflies like to get drunk, while the females shun liquor. The butterflies were placed in a_ screened garden with bowls of whisky and water. The males invariably took to the liquor. Sturdy Bungalow Made of Old Newspapers A HOUSE of cards is proverbial for instability, but that a house can be made of old newspapers, and still serve as a durable dwell- with waterproof varnish. A number of windows are provided, making the “ news- paper home” light and airy. ing has been dem- onstrated by Ellis Stenman, at Rock- port, Mass. With the aid of his wife and daugh- ter, Stenman built a bungalow. en- tirely of shingles made of old news- papers compressed and glued together. The house is shingled both in- side and out with this odd material, which is covered Attractive Massachusetts bungalow built of newspaper shingles

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courage Chemistry Supplies Police with New Weapons by E of the newest of chemistry’s contributions to the police war on crime is a burglar-proof cash-carrying case. Just inside the cover is a gas bomb that explodes if the bag should be opened by thieves who do not know of the safety catch. Another effective weapon (at the left) js a policeman’s club containing a tear- gas bomb at the end of it. On the right is a chemical device for protecting a bank cashier’s window from the de- predations of bank bandits. When these safety devices come into wide use, the inventors believe they will serve as a powerful check to banditry of all kinds. The use of tear gas already has proved its worth in aiding officers to cope with desperate criminals. Police safety case and gas weapons A Lone Survivor THE maidenhair tree, introduced to the Occident from China and Japan, is the only survivor of an extensive family of prehistoric plants. It grows 100 feet tall and has leaves resembling a maiden- hair fern. POPULAR SCIENCE MONTHLY The Prince of Wales Sculptured in Butter NE of the many unique exhibits at the British Empire Exhibition at Wembley, England, is a statue of the Prince of Wales standing beside his horse, done entirely in Canadian butter and housed in a special cabinet kept cool by a special refrigerating plant so that the work of art would not melt away during the exposition. In the background is an accurate replica of the Prince’s ranch house in Alberta, Canada. Two and one half tons of butter were used and two sculptors of the Canadian Government Commission— George D. Kent and Beauchamp Haw- kins—labored for several days in a temperature of two degrees below zero while they were completing the work. The lifelike statue is of especial interest in view of the Prince’s visit to the United States this fall to attend the international polo matches between America and Great Britain at Meadowbrook, L. I. This is the first time in 10 years that this polo Farm Wagon de Luxe Built from Old Auto DISCARDED motor-car was util- ized in an ingenious manner by an Illinois farmer to build a smooth-running tubber-tired farm wagon. The automobile-wagon drawn by a team of horses He removed the body, motor, trans- mission, and propeller shaft, after which he fitted a wagon body to the chassis. _ Then, by a method of his own invention, he fitted a wagon tongue in such a way that his team of horses pulls on the frame but steers the chassis by the original steering knuckles and tie rod. Equipped with pneumatic _ tires, the combination makes a wagon which the owner says makes haul- ing a pleasure over even the roughest roads. classic has been played in the United States. The visit was made at the invitation of the United States Polo Association. A number of the Prince’s polo ponies were shipped to America. Tinie pee tab wht. col Swarm of Bees His Bonnet ‘THE latest thing in daring styles in headgear is a bee bonnet and chin strap of live bees. The brave wearer is Frank Bornhofer, of Tobascdo, Ohio, a raiser of honey bees, who gathers them about him in this strange manner just to show on what friendly terms he is with them. He performs this feat, he say ut suffering a single sting. All of which would seem to indicate that bees are not likely to molest a person who knows how to handle them.

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ital ee ria ete meat afte Pole tae 62 POPULAR SCIENCE MONTHLY Fence of Spinning- Wheels Is an Unusual Advertisement HAT is prob- ably the only spinning-wheel fence in the world has been erected by Elmer Zimmerman, a dealer in antiques in southern Penn- sylvania. Thousands of motorists travel- ing along the Wil- liam Penn Highway, which skirts this curious exhibit, are attracted by the un- usual sight, and undoubtedly many sales of the antiques to be found inside the house have been made because of the appeal of tradition behind this graceful advertisement. At the right of the house may be seen a historic four-horse Conestoga wagon covered by a rustic shed with a roof that is built of earthen tile. While placing these tiles when roofing the shed, Mr. Zimmerman discovered lettering on some of them stating that they were baked in 1746, AN “ELECTRIC” bee- hive, said to have resulted in increased output of honey, has been perfected by M. R. Borlase Matthews, British inventor. The bee- hive is lighted and heated by electricity during the winter, with the result that the bees start to collect honey earlier in the spring than usual. Plans to Swim the Channel in a Rubber Suit MANY attempts have been made to swim across the English Channel, but none more unusual than that planned by Miss Zetta Hills, British champion swimmer, who will wear a suit of rubber especially designed for the purpose. The suit is intended to protect the swimmer’s body from the cold during her long journey in the water. Since it allows free movement of the limbs, Miss Hills believes it will not retard her progress. Zettt Hills wearing her rubber suit Baltimore Man Builds Modern Noah’s Ark MODERN Noah’s Ark has just been launched in the Mud Islands near Baltimore, Md. The odd craft is 50 feet long, 12 feet wide, 12 feet high, and contains six rooms. The “ark” is to be modernized by the addition of two gasoline motors and elec- trie lights, after which the builder, Allan Risley, and his family, will go cruising. New Sandpaper Lithography HILE studying art in Paris, Norman Jacobson, of Coketown, Wyo., ac- cidentally discovered a new method of lithographing that promises to provide endless recreation and interest for the artistically inclined. The young American etcher picked up his ink-roller one day and, without think- ing, he rolled it over a piece of sandpaper. He noticed that the sandpaper would not take ink. He then drew a design on it with wax crayons and inked the sand- paper, with a result not unlike that ob- tained frem a regular lithographing stone, but accomplished without the expensive stone. It is said that brilliant effects ean be obtained by using an ordinary clothes-wringer as a printing-press. Mr. Jacobson says that the discovery will be of especial value to schools, as no expensive equipment is needed. The negatives need not be drawn. Silhouette pictures cut from magazines will give a similar result pasted on the sandpaper, inked and run through a wringer. How a Queen Bee Travels ANDY little bee containers are used in shipping thousands of queen bees through Uncle Sam’s postal service each year. The containers are hollow blocks of wood with screens. The royal bees are put in a compartment with a piece of candy to dine on. Boxes of queen bees ready to mail

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lent earthen placing > = When e shed, merman lettering of them at they in 1746, R1C”’ bee- to have ncreased honey, verfected Borlase British The bee- ited and - winter, 60 collect usual. ravels are used een bees ice each v blocks bees are piece of Four Hours POPULAR SCIENCE MONTHLY of Sunshine in Alaska in Midwinter — a 5 tore remarkable picture from Alaska shows four positions of the sun during four hours when it appeared above the horizon in the month of December. At the left the sun may be seen rising at 10a.M. Next is its position at 11 A. M. In the center is shown its position at noon- time, then at 1 P.M. and finally at the right, its setting at 2 P.M. Five photo- graphing exposures were made to form the picture. Because that part of the earth is turned away from the sun in the winter, perpetual night reigns in the arctic regions for months at a time. During the short time that the sun may sometimes appear, it is so weak that it has little effect, either in light or in warmth. Motorcycle Is Power Plant and Conveyance The Welsh tinker and his movorcycie waididiins TINKER de luxe who tours from village to village by motorcycle is now plying his trade in South Wales. Grindstones and attachments are so arranged that the motorcycle engine runs them. When work is done, the power may be turned back to its original use and the owner chugs off with his outfit to the next field of action. This ingenious device is much more effective than the old-fashioned treadle method and the tinker is able to cover con- siderably more ground, so that if one village offers little work, he quickly moves on to the next. The notice that the unusual outfit attracts also serves as an advertisement. Opticians Are Now Offering Rectangular Eye-Glasses (GLASSES may soon be adjusted to suit the individual as easily as a collar may be bought to suit a man’s neck, if we follow the latest fad that comes from Ger- many, The Germans now make spectacles with movable rectangular lenses that can be eynnnaed about to best fit the face or taste of the wearer merely by shifting the frames. The United States’ opti- cians have given thought to the same _ subject, but until now have retained the circular lens merely chang- ing the type oi the frame to Rectangular eyeglassframes Shell. Acetylene Sound Signals Used on Lighthouses ON THE lighthouse of Dhuheartach, 15 miles or more from the west coast of Scotland, an automatic acetylene de- tonator is used in conjunction with the light. Once started by the lighthouse- keeper, it gives forth its warning every 30 seconds. Placed above the lantern, the sound can be heard in all directions. Before the adoption of this device, the keeper had to set off the signals by hand, so thatit took five minutes to set one off in- stead of the 30 seconds taken by the auto- matic device. In the absence of a keeper, the setting off or the stopping of the signals can be con- trolled by electric buttons from the shore, by means of a cable to the light-house. In Scotland again, in the estuary of the Clyde, there are two of these sound signal stations, and they are controlled by wire- less from the shore, the wireless emissions opening the acetylene chamber valves and releasing the detonator. Plastic Ball for the Ears Shuts out Sound ECAUSE the street noises of Paris have become so great, a chemist has perfected a tiny plastic ball that will fit any ear without danger of injury to the drum. It is recommended to “‘light sleepers, nervous persons, or invalids whose recov- ery depends on sound sleep, and to in- tellectual workers.”” Swimmers, too, are assured that the little balls will keep their ears free of water. Chinese Workman Carves the Smallest Ivory Skull CARCELY as big as a tooth, the tini- est skull in the world was brought recently to the United States. It took infinite patience and skill at the hands of a Chinese workman who labored many months to complete the curiosity. It is complete in every detail and carved from a minute piece of ivory, small enough to fit on the tip of a pencil, as shown in the illustration below. Tiniest ivory skull on pencil point

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i ee ee Sides se Ay a lee Cleanser in Handy Bottle ‘*Knocks’’ Spots off Clothes A NEW device for quickly removing spots from garments consists of a bottle of cleaning fluid with porous cap attached. All that is necessary to remove a spot is to turn the bottle upside down and rub the cleanser on the garment. No rags are required and there is said to be no evaporation or objectionable odor. The cleanser penetrates the cap in correct quantity for use. The makers of the cleanser claim that no fabric is too delicate for its ministra- tions, and that it will save many a trip to the cleaner’s. The little bottle will be found particu- larly useful in the week-end bag or to tuck away in a corner of the car when going on a tour. Removing a spot with the cleanser THAT one man’s meat is another man’s poison is well illustrated by a newspaper item that states that Ohio recently im- ported 7000 wasps from France. The wasps are brought to this country to fight the corn-borer, and if they do all that is expected of them, they will save millions of dollars yearly. Ohio needs the wasps and France is glad to be rid of them. POPULAR SCIENCE MONTHLY ee Grain Easily Unloaded by Use of Platform O ELIMINATE a great amount of handling and to increase the speed of unloading grain from grain wagons in western Canada, simple automatic un- loading platforms are devised by cutting a section of planking from the unloading platform and hinging it in the center. sna Foote Another section is placed so that the wagon wheels will track when driven over it. A cradle arrangement is provided with tipping apparatus that lowers the rear wheels and raises the front ones, thus per- mitting the load to be dumped easily. Atoms of Atoms bed after the phenomenon of radio- activity pointed the way to the dis- covery that all matter was composed of infinitely small charges of electricity, science still clung to its theory that the atom is the smallest particle of a substance that could exist and retain the properties of that substance. Recently; though, science discovered that atoms can be subdivided further without losing their identity. These chips from atoms science calls “‘isotopes.”’ They are the atoms of atoms. An atom of gold, according to the new theory, would be made up of many isotopes, each com- posed of a different kind of gold. Eight different kinds of tin compose an atom of tin, say the physicists who accept this amazing theory, and other substan- ces are equally complicated. Four Drawing Instruments Contained in One Combined in the one in- sirument is found a rule, T-square, protractor, and compass. Its use saves many wasted motions a 8 SERS of draw- ing instruments will give a warm welcome to a T- square, the head of which is a_ pro- tractor. The blade and lower edge of the protractor are marked with scales, and a sliding attachment on the blade serves as a guide for the pencil when drawing exceptionally large circles with the cen- ter of the head as a pivot. The pin shown below the rule holds the instrument to the drawing-board. The invention combines rule, T- a | square, protractor, ; and compass or dividers. It sim- plifies the reading or determination of angles, is an aid in plotting land, in fact, its makers say that it opens up an entire- ly new field of drawing technique, and that it saves a great deal of lost-motion by combining the four instruments in one. Six-Inch Slide Rule Gives Accurate Calculations ALTHOUGH only six inches long when closed, a new slide rule, with divi- sions marked on a spiral, has the same accuracy as a straight slide rule 66 inches long. Two cylinders are used, one sliding inside the other and both carrying scales. They are connected by a short blank cylinder on which two arrows are ei graved. For general calculations the lowef arrow is placed opposite one given figure on the lower scale, then the upper cylindel is slid down into the first one until the second given figure appears opposite the top arrow. The result is shown on thf upper scale by moving the bottom arrow to the top one.

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orm that the n driven ided with the rear thus per- -d_ easily. Gives ons yng when rith divi- the same 66 inches 1e sliding ig scales. rt blank are el- ie lower en figure cylindes until the osite thi n on thf m arrow Woikmen inoving furniture into the steel- jncased vault for fumigation against moths POPULAR SCIENCE MONTHLY One night in this vault, after an application of a fumigator, will rid furni- ture of moths Fumigating Vault Kills Moths in Furniture — in furniture may be destroyed quickly without removing any of the upholstery, according to the inventor, by placing the piece of furniture in a fumigating mothproof vault overnight. The vault is constructed of specially pre- pared wood, chemically treated and in- cased in steel. It is airtight and the fumigant is sufficiently penetrating to kill all moth life in one application without harming the upholstery, it is claimed. The dimensions are 10 feet wide, eight feet deep, and six feet high. Smaller cabinets are also made to keep clothes in. THE ailanthus tree, rapidly becoming a weed menace to New York and Pennsyl- vania, is said to produce a high yield of pulpwood, found to be suitable for book paper. E eet eas Electric Finger-Nail Polisher Saves Time and Labor O LONGER will a woman have to spend much valuable time in polish- ing her finger-nails. A French manufac- turer has brought out a device that does the task in two minutes or less, depending on the height of polish desired. All that is necessary is to hold the hand next to the buffer and let the machine do the rest. The machine consists of a miniature electric motor with attachment for con- necting it with the standard lighting cur- rent, and a buffer mounted on the axle. When the motor is turned on, the buffer automatically revolves rapidly, polishing the nails in a few moments without harm- ful friction. SoME day we shall be using 1,000,000 volts in electrical transmission. Such a line could transport more than 1000 miles of energy, which is equivalent to power generated by 25,000,000 tons of coal. A Tube 210 Miles Long A STEEL tube, 16 inches in diameter and 210 miles long, which, when completed will be one single piece, is under construction between Beaumont, Tex., and the natural-gas fields near Shreveport, La. That a jointless tube of such tremendous length is possible is due to the fact that every junction between sections is sealed by oxyacetylene we!d- ing. Ordinarily they would be joined to- gether by screw couplings. This pipe line which will carry natural gas to Beaumont, crosses two rivers, many creeks, and runs underground through four counties. 65 Knob Controls Automatic House Guard Lock N AUTOMATIC guard lock for doors takes the place of the usual chain and slot for allowing a door to be opened partly while still keeping it locked. By turning the knob to the right, the new lock automatically engages the guard that is attached to the door-jamb, allowing the door to be opened only to the end of the guard. By turning the knob to the left the door may be opened without engaging the lock. As the lock has no keyhole that may be reached from the outside, it forms a posi- tive burglar device when left on con- tinually. This guard lock is burglar-proof ACCORDING to a report from the Chemical Society of England, synthetic marble, ca- pable of taking a high polish, has been made sodium carbon, recently by heating hydrated paste of precipitated chalk and a solution of common salt for eight hours at a temperature of 300° C. and a pressure of 24 atmospheres. China Adopts American Concrete Tile Roofs N CHINA, concrete roofing tile is taking the place of the ancient clay American machines in Hongkong are making concrete tile and brick for 250 tiles. houses to be erected at a cost of about $7000 each. They will be two-story houses having six rooms. Hongkong’s housing shortage is so great that every one of the 250 dwellings was sold before it was com- pleted. Fourteen million brick will be used in the gar- den walls that will surround the houses in English fashion. Sand used for the manufacture of the roofing tile is brought to the j plant by Chinese women, who carry it from a pit in a near-by mountain by means of bas- Above: A new sight in China —American concrete - tile roofs, recently s. ‘actetaend- te kets hung over their the construc. shoulders. The makers turn out about 11,000 bricks a day and 3000 tiles. tion of new housesin Hong- kong. At left: The old Chi- nese clay tiling

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New Mi POPULAR SCIENCE MONTHLY leposts in -Radio Recent Contributions to the Progress of Broadcasting By Jack Binns America’s Most Popular Writer on Radio HEAPER vacuum tubes and , marked changes in the types of tubes commonly used seem to be foreshadowed by the fact that the last basic patent on the vacuum tube will expire early next year. Many radio engineers now are con- centrating their efforts on the de- velopment of new types of tubes. Undoubtedly the expiration of the patent will result in an increase in the number of independent manufac- turers, and that should mean lower prices to the radio listener. Though many rumors are heard regarding the future plans of the leading manufacturers of tubes, only A smaller sizes and incorporated in a special type of transmitter, whid, makes them available for use op ships. The United States gover, ment has adopted them, and is in- stalling them at present on the“‘Rum Fleet” cruisers patrolling the Atlantic coast to prevent liquor Smuggling, Similar sets will be placed on navy destroyers. Using House Current T IS interesting, too, that the present widespread activity jn vacuum-tube development may lead to what long has been a dream of radio inventors—a practicable meth. od of employing house electric current in place of batteries. Several schemes for its achieve. ment have been described in this department, and now Dr. A. W. Hull, of the General Electric Company, attacks the problem from an entirely new angle by his invention of a novel type of vacuum tube. This gigantic loop aerial, said to be one of the largest in Europe, was erected at the top of a London office building recently by the U. S. Shipping Board to pick up messages from the United States. The aerial, measuring eight by eight feet, is wound with 48 turns of wire 1536 feet long. It is turned by means of an auto steer- ing-wheel located in the operating room (left) In this tube, instead of heating the filament by the direct introduc. tion of electric current, the current is connected with an ordinary tungsten electric lamp filament, which does not enter the radio circuit. Fitting New Transmitting Tubes RANSMITTING tubes, too, are receiving their share of atten- tion. Last year engineers of the Bell System developed a powerful new type the largest of which has an out- put of 100 kilowatts—200 times the power of a typical large broadcasting station. These tubes, you may recall, have their plate element on the out- side, sealed to their-glass walls. Now these tubes are being made in The initial success of Uncle Sam’s_ coast-to-coast air- snugly over this filament is a thimble shaped element of a metal alloy capable of a high rate of electronic emis- sion. When the tungsten is heated, the heat is transmitted to this element, which actuates the tube in the usual way. Since the tungsten is not connected with any part of the radio set, it makes no difference whether it is heated by direct or alternating current, nor is there any danger of either the set or the operator using it being injured. Below is H. L. Swart, radio en- gimeer, operating the five - kilowatt arc transmitting set, which is on duty 24 hours a day at the air- mail headquarters R. H. Redmond, European Radio Supervisor of the U. S. Shipping Board, turning the steering- wheel that controls the huge loop aerial that he designed. Seated is L. F. Butler, chief radio operator of the London station, which receives wireless messages from a distance of 8000 miles plane mail service, has been due largely to the perfec- tion of a radio dispatching seas system through which : the cross-country pilots receive their flying one definite announcement can be made, and that is that a new tube to replace the 201a will be introduced shortly. So far as current consumption is concerned, this will stand midway between the UV-199 and the UV-20la, and it will have characteristics resembling those of the latter. Its base will be made of heat- resisting glass instead of metal-incased porcelain. Though the filament of the new tube will consume slightly more current than the UV-199, it is expected that it will be suitable for dry cell operation, except in large multi-tube sets. The introduction of this new type of tube will affect many radio enthusiasts, especially, of course, those whose sets are designed to use only 201a tubes. orders, weather re- ports, and other information station in Wash- ington, D.C

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rated ing ter, which oF USE on CS govern. and is in- the ‘Rum ne Atlantic smuggling, on navy Irrent that the ctivity in > may lead dream of able meth- e electric 2S, S achieve. ed in this \. W. Hull, Company, an entirely | of a novel of heating t introduc- > current is y tungsten vhich does t. Fitting a thimble- etal alloy ronic emis- eated, the ent, which way. ected with makes no by direct there any e operator is H. L. radio en- operating ve - kilowatt ansmitting hich is on 24 hours a it the air- neadquarters . in Wash- n, Dee The Radio Lighthouse ADIO has brought about many R changes in present-day life. Now it seems likely to cause the elimination of a useful and picturesque institution that has endured ever since ancient man lighted his beacon fires to guide the home-coming mariner—the lighthouse. The lighthouse service of the Depart- ment of Commerce is conducting a series of important experiments with the radio beacon, or radio fog signal on the light- ship at Nantucket Shoals, where all trans- atlantic shipping converges. The radio beacon depends for its efficacy on the difference in the speed of sound waves and radio waves. From the lightship radio signals and sound signals from a submarine signaling device are transmitted simultaneously. The former travel 186,000 miles in a second, the latter only 1000 feet in the same time. The radio signals, then, will POPULAR SCIENCE MONTHLY ¢ eae At a farm on the New England coast, engineers of the Bell System laboratories are quietly in- vestigating the causes and habits of static by means of the instruments shown above. This apparatus records the strength, direction, and duration of all static discharges within its range. By studying the records, which are printed automatically, the engineers hope eventually to devise some means of eliminating static At the same location the Strength of signals received from British transmitting sta- ‘ tions is being studied by Means of the measuring instrument shown at the Tight. This work is Preliminary to the estab- lishment of the first com- mercial transatlantic tadio-telephone service be received by a ship virtually the instant they are sent, and, from the length of time that elapses before the sound signals are received, the distance of the ship from the source of the signals can be calculated. Special clocks have been designed for ships, which automatically convert this a neces. First successful experiments in radio trans- mission and reception from a speeding ex- press train in England were made recently difference in time into distance in miles. A radio compass enables the navigator of the ship to determine accurately his direction from the lightship, so that the exact position of his vessel is made known to him as soon as he approaches close enough to the lightship to receive its signals. For Greater Safety HE U.S. Army Air Service recently produced an improved form of ‘direction finder’’ for use on aircraft as an important adjunct to aerial naviga- tion. Itwastried out at theexperimental flying station at McCook Field, Dayton, Ohio, by Capt. W. H. Murphy and Lieut. A. J. Lyon in a De Haviland bi- plane. periments the i, Fae POR erercseras a I new device was given a serious practical test when the plane ran unexpectedly into a dense fog. It proved its value by- guiding the aviators safely back to their landing field. It will help make the air- mail service and future passenger services safe, irrespective of weather conditions. During the ex- on the London and Northeastern Railway by members of the Radio Society of England, who are shown above with their radio sets A Municipal Experiment HE new municipal broadcasting sta- tion WNYC in New York has been compelled by circumstances to try a novel experiment. As a result of certain differences of opinion between the city and private corporations, it has been impossible to secure connecting wires to the studio of WNYC for outside con- certs under the remote control system. As a result of this situation the en- gineers employed by the city are ex- perimenting with the network of wires used by the Police and Fire departments for alarm purposes. Should these ex- periments prove successful, a new era in broadcasting will be opened up. In fact, municipal broadcasting may well be the ultimate solution of the problem: ‘“‘ Who shall pay for broadcasting?” Telephone wires actually are employed to transmit many telegraph messages simultaneously with telephone conversa- tion. There seems to be no reason why the city’s telegraph system cannot be used as a feeder to its broadcast station. Setting Clocks by Radio HE U. S. Bureau of Standards is experimenting with a radio clock-setting appara- tus with the object of permitting the Arling- ton naval radio station to control automati- cally the clocks of the country as well as those of ships. The main object, however, is to elim- inate the necessity of radio operators changing from the universal wave length of 600 meters on which SOS signals are sent. The ships therefore will get standard time signals without any lapse in the watch that protects life at sea, An easy way to build an attractive radio cabinet is described on page 85 of the Home Workshop Department,

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POPULAR SCIENCE MONTHLY Slow to Build a Super-Heterodyne Part [l—Intermediate Frequency Amplifier and Second Detector By Joseph Calcaterra An article in last month’s issue told how to construct the first two units of the super-heterodyne receiver—the oscillator and first detector unit, and the two-stage audio-frequency ampli- fier unit. The following article tells how to complete the set. Number 42 is a standard 400-ohm potentiometer; 43, a 1-microfarad fixed condenser; 44, rheostat controlling the filament current of the three radio- frequency amplifier tubes, 54, 55, and 56; 45, rheostat controlling the filament current of the second detector tube 57. Number 46 is the binding post which 59, second radio-frequency transformer; 60, third radio-frequency transformer; 6] a .00025-microfarad grid condenser: 62, a 2-megohm grid leak; 638, the positive B-battery. terminal of the radio-fre- quency stages. Begin the wiring by running a wire from terminal 41 along the top of the baseboard and in front of the Tie intermediate fre- quency amplifier and second detector unit forms the middle members of the complete super-hetero- dyne receiver. Figure 1 on this page shows the layout of parts for this unit, while Fig. 2 is the wir- ing diagram. All parts in the iwo illustrations are lettered with corresponding numbers and symbols that will be referred to in this article. The new low-frequency (long - wave - length) signal that is formed in the oscil- F terminals of the sockets, to terminal 48. Then connect the F; terminals of the sock. ets with this wire by short lengths of wire. Another wire is used to connect the wire just mentioned with the A ‘terminal of potentiometer 42 and the B terminal of con- denser 43. EXT, run a wire from terminal 40 to terminal 47, and join the B terminals of rheostats 44 and 45-and the B terminal of potentiometer with this wire by using short lengths of wire. lator and first detector unit by combining the oscillations produced by the local oscillator with the oscillation re- 6 54p p 58g Fig. 1.—The layout of parts for the intermediate frequency amplifier and second detector unit of the super-heterodyne receiver G55 pp 59g ceived by the first detector tube from the loop or aerial, is passed into the grid circuit of the Now join the F2 terminals of sockets 54, 55, and 56, and the connecting wire with the A 46 terminal of rheo- G 5ST p stat 44. The A terminal of rheo- stat 45 is con- nected with F> terminal of socket first radio - fre- quency amplifier tube, 54, by the 57. The B terminal of condenser 50, filter coupler. This +A” BATT. consists of coils 51 and 52, which are 3.4 +8 FIRST DEL so designed that they will pass the oscillation of the required frequency and will suppress undesired oscillations. The signal then is amplified at the long wave length by a series of radio- frequency. amplifier tubes and _ trans- formers and passed into the detector stage to be reduced to audio-frequency and further amplified at audio-fre- quencies by the audio-frequency am- plifier unit. For the sake of clarity, in referring to the various units, the oscillator and first detector unit will be called ‘‘unit 1”, the intermediate frequency amplifier and second detector unit, ‘‘unit 2,” and the two-stage audio-frequency amplifier unit, “unit 3.” The complete set with the three units combined is shown in Fig 3. Number 39 is the binding post con- nected with binding post 21 of unit 1 to complete the plate circuit of the first detector tube. Numbers 40 and 41 are A-battery terminals connecting the A-battery circuits of unit 1 with the A-battery circuits of unit 2. Number 40 is the negative A-battery ter- minal, and 41 the posi- tive A-battery terminal. UNIT NO.1 Fig. 3.—Complete super-heterodyne set, showing the three units combined Fig. 2.—Wiring diagram for the same unit, with parts lettered and numbered correspondingly is connected with binding post number 24 of unit 3. UMBERS 47 and 48 are the binding posts with which .binding posts 25 and 26, respectively, of unit 3 are con- nected in order to connect the filament circuits of unit 3 with those of unit 2. Number 47 is the negative A-battery lead terminal; 48, the positive A-battery terminal lead; 49 and 450, .00025- microfarad fixed condensers; 51, the plate coil of the filter coupler; 52, the grid coil of the filter coupler; 53, the positive B-battery terminal of the first detector; 54, the first radio-frequency amplifier tube; 55, the second radio- frequency amplifier tube, and 56, the third radio-frequency amplifier tube. Number 57 is the second detector tube; 58, the first radio-frequency transformer; UNIT NO.2 just visible behind coil 51, is con- nected with ter- minal 39, and the outside end, 0, of coil 5 is joined with the connecting wire. The A terminal of condenser 50 is connected with terminal 53 and the in- side end, J, of coil 51 is joined with the connecting wire. The B terminal of condenser 49 is connected with the G terminal of socket 54 and the outside end, O, of the coil 52 is joined with the connecting wire. The next step is to suspend the grid leak and condenser in midair by connect- ing the B terminal of condenser 61 with the G terminal of socket 57. The A terminal of condenser 61 is connected with the G terminal of transformer 60. The grid leak, 62, is slipped into the condenser clip made to receive it. Now connect the P terminal of socket 56 with the P terminal of transformer 60; the P terminal of socket 55 with the P terminal of transformer 59; the P ter- minal of socket 54 with the P terminal of trans- former 58; the G termin- al of socket 56 with the G terminal of trans former 59; the G termin- al of socket 55 with the tA BATT. : G terminal of trans UNIT NO.3 former 58. (Continued on page 157)

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ne or sf ormer; rmer; 6] ser; 62,4 Positive ‘adio-fre- y a wire p of the nt of the ckets, to connect the sock- by short ther wire the wire h the A meter 42 of con- ire from terminal minals of -and the tiometer ng short erminals | 56, and necting the A of rheo- The A of rheo- is con- rith F»2 f socket terminal ser 50, e behind is con- ith ter- and the d, O, of ng wire. r 50 is _ the in- with the r 49 is f socket the coil ’ wire. the grid connect- 61 with The A ynnected ‘mer 60. into the ic. of socket rmer 60; h the P 2 P ter- 54 with of trans- ; termin- with the trans ; termin- with the f trans- age 157) A Coast-to-Coast Radio Set Built By L. Grant Hector, Ph.D. OAST-TO-COAST reception on a ‘+ homemade set costing only $15.25! That statement doesn’t sound reasonable; but I am doing it, and so can you. Medford, Mass., Los Angeles, Calif., Atlanta, Ga., Fort Worth, Tex.—all are within its range. And the interesting part about this set is that there isn’t any- thing tricky or complicated about it. It is easy to build and simple to operate. There are not even any taps on the coils. The set combines utmost selectivity with great range and intensity. Of course, if you are to build this set for $15.25, including the cost of phones, tube, and B battery, you must be willing to make most of the parts, such as conden- sers, and coils for loose couplers, and a variometer. In any case, you will want to do the assembling yourself. If you care to spend a little more, you can buy your coils ready wound. The phones used were of the ordinary radio type, and they were plenty good enough to bring in all the above-named stations from Cleveland, O. The panel was just a piece of thin white boxwood. [N THE wiring diagram at the bottom of this page, L, is an ordinary variometer and tunes the antenna circuit. The antenna should be one wire not lenger than 125 feet, preferably about 100 feet. The lead-in comes from the end, not the middle. Figure L, is an ordinary loose coupler. Notice that one end of the secondary coil is fastened to the ground end of the primary coil. This connection will eliminate about 90 per cent of the howling due to body capacity. Figure L, is another loose coupler. Its primary is connected in series with the secondary of the first loose coupler, as shown in the diagram. The secondary of L, is connected in the plate circuit. The wide-range receiving set which can be built for $15.25. POPULAR SCIENCE MONTHLY for $15.25 By choosing coils of the right size, it is unnecessary to have any of them tapped for the range of wave lengths now in use for broadcasting. The dimension of coils and number of turns that I have used on my own set are as follows: ae. Diameter No. of Turns i ore 31% in. 14 S A 20 L I es 3% “ 30 3 yA S 2%“ 50 If you use ready-made loose couplers, you probably will find that they contain more turns than are required in this set, and you should remove the extra turns. If the sizes of your coils are different from those given above, you will need to use a slightly different number of turns. The larger the coil, the fewer turns required. It is an improved three-circuit regenerative receiver can be bought at a ten-cent store and assembled easily if one does not wish the trouble of cutting out his own plates. The movable plates are the ones connected with the ground. This connection will further reduce the effects of body capacity. Figure C, is a small fixed phone con- denser. It can be made by separating two pieces of tinfoil (about 14 by 3 in. each) with a piece of paraffin paper, and wrap- ping the whole about a small piece of card- board for the sake of compactness. Figure C, is a similar condenser with the addition of a grid leak, which can be a piece of cardboard with a pencil mark drawn on it so as to connect the two pieces of tinfoil of the con- denser. also can be purchased ready made. Expensive types are not necessary. I paid 30 cents for the two I use in | my set. f OW come thetube, socket, and rheostat. It is not practicable to try to make any of these. In attaining the re- markable range record with my set I used a soft detector tube. The new hard dry cell tubes now on the market will give almost as good results. Practically all the tuning is done with condenser C,. After the first adjustments have = Wiring diagram for the wide-range set. The lettered is parts are described in the accompanying article Figure C, is a variable air condenser of about 23 plates. I made mine by cutting out half disks from a thin piece of galvan- ized iron. The plates are held apart by small metal washers. All the parts for the economical construction of a condenser been made, you will find that the same setting of L, and L, will hold for nearly all stations, and that the adjust- ment of L, is not very critical. You can go directly from one station to another by turning C,. Technically, this set is a form of three- circuit regenerative receiver elaborated and improved in design. Figures C, and C,..)

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70 POPULAR SCIENCE MONTHLY Radio Hints for the Broadcast Fan a good telephone head set is sufficient to fill a good sized room, just as a loudspeaker does, provided some device to conserve and throw out the sound is attached to the head set. It is possible, for example, to at- tach the head phones to the small end of one of the large brass horns musicians play in a band. An- other device some- times employed is the attachment of the telephone dia- phragm tothe back of a violin, the wood of the violin acting as a sound- ing box. A French loud- speaker designed to be made at home consists.of a cone-shaped roll of heavy paper, like a megaphone, and a small piece of hol- low bamboo. The bamboo is thrust through the paper cone near its small end. The center of the bamboo carries a notch, opening in- side the cone. The head phones are then placed, each against one end of the hollow bamboo tube. The sound enters the bamboo, escapes through the notch in it and comes out through the paper cone. Even a single head phone placed against the small end of an ordinary megaphone will sometimes work quite well as a loudspeaker. Sometimes good results are obtained simply by placing the headphones in a large bowl, a glass lamp shade, or similar object. TS volume of sound produced by OR use around an experimental hook- up, one of the most convenient acces- sories is a supply of the little metal clips used to fasten neckties. You can find them, too, on certain brands of suspenders, In experiments to find a way to eliminate radio’s great bugbear, static, Fred Wundsam, of New York City, has perfected the static machine shown above. If a piece of insulated wire is soldered to the rear of the clip and then another clip soldered to the other end of this wire, you have a convenient connector that can be clipped fast in a moment to a battery lead, a terminal, or a bus wire. The When the machine metal teeth on the business end of the clip always provide a good contact with whatever it is fastened to. HOMEMADE variable grid leak may be contrived in a few moments from an ordinary rubber band and a little pow- dered graphite, as, for example, some of the black lead from a soft lead-pencil shaved off and ground with a penknife blade to a fine powder. Rub the powdered graphite well into the surface of the rubber band and then mount the band in the set so that the terminals to which it is attached can be moved apart in such a way as to stretch the band. This will increase the re- sistance of the grid leak; allowing the band to shorten itself will decrease the resistance. The current is carried, of course, by the thin layer of graphite on the rubber. T IS not gen- erally known that almost any form of carbon, for example, either coal or coke, may be used as a crys- tal detector in place of galena or a similar mineral. The use of coke does not usually re- quirereadjustment of the catwhisker. A small bit of coke saturated with No doubt you have heard of the radio C battery, but do you know how The C battery is a flashlight battery, or its equivalent, placed in the negative filament lead of the transformer. The negative side of the battery is connected with the negative filament to hook it up to your set? quicksilver is said to be even better than the coke alone, is operated in connection with his receiving set, the noise produced in the loudspeaker is said to resemble the roaring of a cannon. The photo shows Mr. Wundsam at his work [= IS important to handle your head phones quite as carefully as you do your vacuum tubes. Inside each head phone there is a small permanent magnet. Any shock to this magnet—dropping it or knocking the head phone against the table—will weaken the magnetism. This makes the head phone _lesg sensitive. It can be remagnetized, however, by send- ing it back to the makers. HE hard rub- ber or “‘ebon- ite” used for panels and coil tubes and similar purposes may be cut, bent, andworked easily if it is softened for a few minutes in hot water. The water should not be boil- ing, just hot enough to be un- comfortable to the hand. If it is too hot the rubber will melt altogether. * This electron vacuum tube, said to be the first ever constructed, is at the National Museum in Washington, D.C. It was made in 1898 by D. McFarlan Moore of New York. Radio waves from it were used to set off a bomb and blow up a miniature battleship Maine T IS a good idea to keep a running record of the number of hours that you use the batteries on your radio set, espe- cially if you use dry batteries. Nothing is more annoying than to find that your batteries have run down just when you especially want to hear a certain program. Keep a little note-book close to your set. For other useful radio hints, turn to page 133 in The Home Workshop. There you will find how to make a winder fot preparing coils; an. adjustable loop aerial, and a loop former for making radio connections.

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in * head ‘ou do | head jagnet, ig it or st the veaken >tism, S the e lesg It can etized, ’ send- to the d rub- ‘ebon- panels es and poses , bent, asily if d fora -in hot : water e boil- ; hot be un- to the is too er will her. unning 1at you , espe- othing it your on you ogram. yur set. urn to There der for 2 Joop naking biles regularly probably have a very clear notion of ‘what makes the wheels go round.” How many radio enthusiasts, though, know exactly what process music or speech goes through hefore it is heard in the head phones? Radio is so new and apparently so complicated that the newcomer in the ranks of broadcast fans fears that its details are beyond his understanding, and so he is content merely to twirl the knobs of his set and listen in. Now, there is no reason why this should Me persons who drive automo- POPULAR SCIENCE MONTHLY How Broadcasting Works The First of a Sertes of Articles on the A-B-C’s of Radio By Robert E. Martin ITH this issue Popular Science Monthly presents an expanded and improved radio department. Each month na- tionally known experts will offer you in short, pithy, understand- able form the radio information you really need to keep abreast of the times and to make the most of your outfit. It will pay you to watch this section for the latest radio news and the most timely operating and construction ad- vice. - The readers of Popular Science Monthly are well acquainted with Robert E. Martin as a writer who knows how to interpret the tech- nical terms of science in readable language. Beginning on _ this page is the first article in his series on ‘‘How Radio Works,’’ which will give you a new and clearer understanding of broadcasting and reception.—THE EDITOR. be the case. Though the average receiv- ing set is an immensely complicated ap- paratus, though a transmitting station is even more complex, the fundamentals of radio are simple. With a clear under- standing of them, the satisfaction you derive from your radio set will be in- creased immeasurably. Take the matter of broadcasting. When a singer performs in a broadcasting sta- tion in New York City, say, and you hear the music in Chicago, you realize, of course, that the sounds you hear are not the actual sounds that issued from the throat of the singer. You know from ex- perience that sounds cannot travel through such an immense distance. What you hear are representations of those sounds, bearing about the same relation to them that a photograph does to the person of whom it is taken. These illustrations show the processes by which the words of the announcer at a boxing match are sent out by radio from a broadcasting station. At the ringside the announcer speaks into a microphone transmitter (1), and his voice is carried over the telephone wire through the nearest exchange (2) to the control room of the broadcasting station (3). Here an operator ob- serves the broadcasting quality of the incoming voice waves and checks any defects before they pass to the transmitter (5). In the transmitter the voice waves are made to modulate, or change, the vibrations of the “carrier wave,”’ which is produced by an oscillating electric current supplied by high and low voltage generators (4). The carrier wave is put upon the ether by the broadcasting aerial (6) and carries the program with the speed of light to radio listeners 71 The music in the broadcasting studio suffers several transformations before it reaches your radio set. The original sound waves are transformed into elec- trical waves and then greatly strengthened —magnified—in order that they may span the great distance between the studio and your receiving set. Then, when those electrical waves reach your receiver, they are so badly spent after their long journey that they must be mag- nified again before they are strong enough to be converted again into sounds that you can hear. you can picture the process more clearly probably, if you will compare it with sending a message to a distant friend, say 3000 miles away. Obviously you cannot speak the message to him across that distance. But you can, for example, dictate your message to a stenographer. The stenographer then transcribes it on paper with a typewriter, and dispatches it through the mail. When the letter is received, the person to whom it is sent can read your message aloud if he wishes. Thus, while he can receive your message in exactly the same words in which you uttered it, he does not hear your voice. So it is with the actual radio program and the sounds you hear in your head set. In each case the spoken word is trans- formed into another medium of commu- nication so that no part of the message is lost. This probably will suffice to explain in a general way what happens between broadcasting station and receiver. Let us examine the broadcasting process more closely. The essential tools of a broadcasting station are the transmitter, the modulat- ing apparatus, and the aerial. The trans- mitter is a complicated apparatus capable of producing radio waves, that is, electro- magnetic waves that will travel from one point to another through the ‘ether’ without intervening wires. The modulat- ing apparatus consists of various instru- ments by means of which these radio waves—called the “carrier waves’’—are changed or“‘ modulated”’ in their vibrations in accordance with music, speech, or other (Continued on page 154) 4 ——— merneaesht 2 ig ee aac

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POPULAR SCIENCE MONTHLY Above is a striking demonstration of how the flexible mounting of the four rear wheels permits the new six - wheel Army motor truck to ride easily over the roughest roads. Notice that two diagonally opposite wheels are passing over large blocks on the roadway without disturbing the other wheels. At the left are shown the two rear axles, with pivoted type of suspension New Six-Wheel Army Truck Absorbs Road Shocks IN an effort to prevent the destruction of highways by heavy motor transport Army engineers at Camp Holabird,Mq_ recently have perfected an unusual ney type of six-wheel cargo truck, which they claim gives the easy riding qualities ang flexibility of a touring car over the roughest roads. These results are said to have beer obtained not only through the use of pneumatic tires on all six wheels, byt through the flexible mounting of foy wheels in tandem at the rear. Instead of the usual worm-driven rear axle, two double reduction axles with a flexible trunion type of suspension are employed, In other words, the two rear axles are pivoted in such a way that they move separately to conform to uneven road surfaces. Thus, one of the rear wheels passing over a large obstruction, will not jolt the Body of the truck nor affect any of the other wheels. The designers claim the truck can be operated over worn-out, pot-holed macadam without the least discomfort to the driver. Both of the rear axles are used for driving and braking. ‘Two sets of four- wheel brakes operate on the four rear wheels. With a full five-ton load, and at a speed of 20 miles an hour, the six- wheeler can be brought to a full stop within a distance of 25 feet. In steering tests the truck was turned in a 68-foot circle on a wet clay baseball diamond. Inside Micrometer for Auto Repair Work NEW micrometer for inside measure- ments in automobile repair work contains a thumbscrew clamping device by which the thimble of the micrometer The in- strument has a range of measurements from two to eight inches on a scale of For taking difficult measurements of small holes an can be locked at any reading. thousandths of an inch. adjustable handle is provided. Taking the inside measurements of an engine cylinder with the microm- eter shown at left ~ Small Crane Handles Heavy Truck Wheels O aid in re- moving and replacing heavy motor truck wheels — a_ task that usually re- quires at least two men — a_ small portable steel crane has ,been perfected for use in large garages and repair shops. One man can op- erate it. At the top of the crane are __ steel jaws, shaped like ice tongs, that grip the top of the wheel rim. These jaws are tightened or released by the turning of a hand crank, which also lowers the wheel after it has been pulled away from the axle. Stops at the base of the es One man lifting a heavy truck wheel with the crane crank hold the wheel steady while it is being taken off or attached. The device is mounted on iron casters so that it can be moved about easily. Automatic Danger Signals for Cross-Roads UTOMATIC warning signals to pre- vent collisions between automobiles at dangerous cross-roads have been tested recently with reported success near Bordeaux, France. The signals are operated electrically. Across each roadway near the intersec- tion is placed a metal plate even with the road level. Whenever an automobile, approaching the crossing, passes over he plate, it makes an electric contact that releases a danger signal at the crossing and on the intersecting road. At night the signals are illuminated for several seconds after contact is made with the road plate. Thus a driver is warned instantly that another car is approaching the intersec tion. The signal: is at sufficient distance from the crossing to give him time to apply his brakes. Installation of the system is said not to be costly.

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r Truck Ocks lestruction transport abird,Mq. usual ney vhich they alities and Over the lave been he use of heels, but y of four Instead axle, two a flexible m ployed, axles are hey move ven road ar wheels 1, Will not iffect any 1ers claim worn-out, the least used for S of four- four rear oad, and , the six. full stop as turned ' baseball eels ile it is casters pasily. ads at the oad. At ited for ide with tly that ntersec- distance time to of the POPULAR SCIENCE MONTHLY American Ideas in New French Car OLLOWING a visit of several months F in the United States, during which he made an extensive study of American methods of quantity production of automobiles, André Citroen, famous French automobile manufacturer, has developed the novel type of inexpensive car pictured here. This car is a light coupe model of unusual lines, especially designed for the person of moderate means. With other models following the same general style, it will be manufactured and distributed in large quantities in Europe to meet an increasing demand for a car of low initial cost and upkeep. In the new venture Citroen is reported to be following Henry Ford’s methods. Rain Stains the Hood AFree your car has been run in a heavy rain, special attention should be given to sponging and wiping the hood. When the hood is fairly hot rain- drops will stain it readily. Portable Scales Aid CCURACY, simplicity, portability, and quickness of operation are claimed for a new type of truck scales with which an inspector can weigh a truck wherever he may happen to be to determine whether it is exceeding the load limit for concrete highways, bridges, and city streets. The device is a portable instrument weighing only 40 pounds. Two models are manufactured. One of these is a small plate on which it is necessary merely to drive the wheels of the truck. The other is designed for weighing on the jack principle. Small dial scales give a quick reading as to whether the truck is an offender in overweight or not. One purpose of this portable apparatus is to increase the effectiveness of road protection crews. With it they can change their locations at will, whereas the locations of permanent scales soon become known to chronic offenders, mak- ing it possible for them to detour and evade the law. Taking the Hills on ‘‘High”’ T BYING to climb every hill on high gear not only may injure the engine of your car, but may result in serious accident. Sometimes it happens*that a driver, attempting to rush a hill on “high,”’ finds, when he gets half way up that the speed of the engine is so reduced it will not accelerate sufficiently to continue climb- Ing on low gear. Then the brakes may fail to work properly and the car backs down hill, perhaps landing in a ditch and resulting in a tragedy. The new French small car which Andre Citroen plans to manufacture in large quantities in Road Protection The portability of the small platform scales is shown above. A truck is weighed simply by running each of the wheels on the plat- form and reading the weight on a dial Complete Ignition System Designed for Fords A COMPLETE new ignition system for Ford cars, similar to the systems used on larger cars, and replacing the usual Ford timer, has been perfected by a concern in Springfield, Mass. The acces- sory can be used on all Ford models, it is claimed. Outstanding advantages claimed .for the new system include automatic spark advance; big, hot sparks at low speed, insuring quick starting; scientifically accurate timing; complete ignition of gas in the cylinders; clean spark plugs and steady power. Setting the Spark Lever N MOST automobile engines having spark advance, the spark lever should be set about half to three-quarters of the way to the top of the quadrant for normal driving. Thereafter the automatic advance, incorporated in the ignition system, will control the spark position.

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74 POPULAR SCIENCE MONTHLY Brooklyn Has Largest Generator ei ort: § ee sag Sees Agta HE largest steam-electric generator in the world was recently put into commission in Brooklyn, N. Y. The gen- erator was built at a cost of $1,000,000, and will generate 50,000 kilowatts of cur- rent, the equivalent of 67,000 horsepower. Within 24 hours of its complete installa- tion it was producing at full capacity. This generator will produce 50,000 kilowatts of current, equiv- alent to 67,000 horsepower, enough to light 10 100-watt electric lamps in 50,000 homes This generator is capable of lighting 10 100-watt lamps in 50,000 homes. Twenty million dollars is said to have been spent on the power station where two such gen- erators were installed. It is expected that by the time the station is fully com- pleted, a similar sum will have been ex- pended. Bricklaying Made Easy for the Amateur NEW bricklaying process is said to allow unskilled laborers to lay from six to 10 bricks a minute, or nearly 3000 a day, without previous training. The system was devised by an Englishman. When the site of a house has been chosen and its plan arranged, uprights, preferably of angle iron, are placed in the ground at the corners and upright T- pieces are fixed between these at intervals of about 10 feet. These uprights form the building line of the house. Boards, usually 10 feet ae long, seven inches deep, and one inch thick, slide against the angle and T- uprights and form the face against which the bricks are laid. The boards are moved along as the work progresses. THERE is one phy- sician to every 724 persons in_ the United States. In England there is one to every 1087 persons, and in Central Europe only one doctor to every 2000 or Uprights and T-pieces guide the amateur bricklayer 2500 persons. Folding Ladder Useful in Home or Fire-House tae of the newest devices is a folding ladder for fire-department use. It is also a handy article for use around the home. When closed, it is merely a roung pole, light in weight, and easily carrieg To open, one side is pulled out, extending the rungs and forming a regulation ladder It is made of straight grained spruce. , This ladder folds up to form a pole A Simple Caliper that Will Give Accurate Readings oT tea the caliper shown below it is possible to obtain accurate readings at a glance concerning the exact fit of a piece of work you have on hand. It is fitted with a dial indicator with a hand that moves above or below the desired size, which is set at zero. After the initial fitting, the caliper quickly shows whether the work in hand = is under or over size and how much. Net Ob HI th It is allows pimsel consist eonnet direct The in dim tion is naturé — Here is a handy caliper that is easy to read, shows if work is under or over size, and how much

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l in e folding se. It ind the | round -arried, ending ladder, ce, 7 Will igs v it is adings t of a It is _ hand lesired -aliper hand er size h. iat is rk is New Field-Glass Permits (bserver’s Concealment HIS new type of field-glass permits the user to sight around corners. is an indirect-vision telescope, and allows the observer to completely conceal himself while using it. The instrument wnsists of a telescope with optical prisms connected with the lens so that the in- It direct view iS obtained. The lens is so large that it may be used in dimly lighted woods and the magnifica- tion is 10 diameters. naturalists. It is of great use to eh eat Pl Unseen, he stalks game with new field-glass Traveling Lawn-Sprinkler Saves Much Labor N AUTOMATIC traveling lawn- sprinkler saves much time in water- ing extensive lawns. It is of the conven- tional whirling type. When the spiral is turned by the force of the escaping water, it moves a set of horizontal gears that are connected with a geared wheel on which theapparatusruns. Thus when the water turns the spiral, the action causes the wheel to travel over the ground radiating in a wide circle. POPULAR SCIENCE MONTHLY Above: Interior of the traveling oil - refinery. F Built on two railway -= cars, it can travel from HI place to place, as neces- sity demands. At right: by Outside the movable re- finery. It can be set up in 10 days, and packed for moving in a week OMETHING new in oil refineries is one built on wheels, recently put into operation in Texas. Being constructed on two large special railway cars, it may be moved to any desired location. The refin- ery is known as a “topping plant” and may be in complete operation 10 days after arrival at a new location and packed up for moving again in a week. Forced air draft for combustion is sup- plied by a suction fan nearly six feet in diameter. One of the features is the condensation of vapor with cool air in- stead of water, this being done by the huge suction fan. 75 Oil Refinery Travels on Railway Cars att - | The refinery is electrically operated throughout. An electric generator opere ated by an oil engine furnishes power for the pumps and current for the lighting plant. The starting power for this large en- gine is furnished by compressed air, this being supplied by a two-horsepower gas engine. The refinery has a capacity of from 1000 to 3500 barrels of crude oil in 24 hours. The special cars are jacked up and placed on concrete foundations while the plant is in operation and two men to the shift can operate the plant. Concrete Viaducts Planned for Traffic Relief MBODIED in the ambitious model pictured below is a proposal to relieve the thickening traffic congestion in very large cities. This proposal contemplates the con- struction of concrete viaducts cutting through the centers of the lines of blocks between the congested streets, where traffic is largely on streets running in one direction. The alleyways under these via- ducts could serve for deliveries, refuse collection, and more ready access for the fire department. At suitable intervals, curving descents would be provided. It is declared that the cost of con- structing these viaducts, even when they must pierce buildings, would prove sur- prisingly low. SAN FRANCISCO has fewer thunderstorms than anywhere in the United States, accord- ing to 20-year records compiled by W. H. Alexander, of the U. S. Weather Bureau. Tam- pa, Fla., has more thunderstorms than any other part of the country. Another bad spot is Santa Fé, N. M., where 1456 storms oc- curred in 20 years.

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76 Man Captures Lightning in the Sand Dunes T REMAINED for Dr. Henry W. Nichols of the Field Museum of Nat- ural History of Chicago to surpass the ancient deities by subduing lightning so thoroughly that he can place it in cement molds. Doctor Nichols’ ‘‘lightning,’’ however, is ‘‘petrified.’’ It consists of an irregular hollow tube of silicate made by a flash of lightning that has sunk itself in a sand dune. When lightning hits a sand bank, the heat is so great as to melt the sand in the path of the electric discharge. A re- pellent current causes each particle to fly off from the others, leaving the path of the streak hollow. The translucent crust forms about the hollow tube in the sand bed, leaving the record of the flash. Some- times little edges of this tube stick above the sand. Some tubes as long as eight feet have been uncovered. FOPULAR SCIENCE MONTHLY Stories Revealed by Earth Strata A STORY that began 15,000 years ago, far back in those dim times before men emerged from the shadows of pre- history, is written in these earth strata. They were found at Laugerie Basse, France, on a spot where, ages ago, primitive men en- camped often and in great numbers. A huge, overhang- Vobdalenion ing cliff that gave shelter, and a stream, probably attracted them. The oldest stra- tum contains the residue of hearth fires, for those an- cient men knew many uses of fire. A few crudely en- graved objects are mixed with the char and_ ashes. Then an empty stratum occurs. During the period of its formation evidently the en- campment was not used. Possibly a great migration emptied theregion, the emigrants lured by tales of teeming hunting grounds elsewhere. The next stra- tum reveals that the returned men had achieved a higher civilization during their ab- sence. A _ sculp- tured reindeer head, amulets, and other proofs that art had been born, were found. Sotoowere flint graving tools. In the next stratum, fine, barbed har- poons appear. More and better carvings on animal bones were left here. Beginning of the Neolithic “Age Rubbish Barren Layer Hearth ashes ic” Then for nearly 3000 years no hums, traces are left. A thick layer of natu rubbish overlays the older records P progress. Then a new race establish Hearth avy The prehistoric objectsem. bedded in the rock strata shown above are, as num bered: 1, 2, 3, and 4, frag. ments of reindeer jaw; 5, animal joint; 6 and 8, frag. ments of reindeer shoulder blade; 7, horse’s tooth; 9 and 10, fragments of rein- deer jaw and spearpoint; 11, flint; 12, double-barbed harpoon; 13, reindeer ant- ler pierced. The height of this section, embodied in the rocks pictured at the left, is about seven feet itself—the Neolithic men. Their polished axes and pottery far e- cel the handiwork of ther predecessors. Dog ani pig bones reveal probable domestication of these animals. A crude but sturdy civi- ization had arrived. Shortly after this period, the record ends. 5 Deaf children learn cheerfully and quickly by the use of radio Deaf Children Taught by the Aid of Radio | pein is now being used for the teaching of deaf children in the I stitution for the Improved Instruction d Deaf Mutes in New York City. By meats of an elaborate and unique radio syste that now is a permanent part of the inst tution’s equipment, wonderful results have been accomplished. Each child has a pair of head phones, which are plugged into a jack in the table, this being connected with a master It ceiving set in another part of the building. As every child’s hearing is different, the various head sets are regulated by meats of resistances in the table to give different intensities, corresponding to the amoutt of the child’s deafness. Officials of the institution have fourd that radio opens up a new field for the successful treatment of deaf mutes and stimulates their interest and hearing.

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rata rs no hums, er of natury ’ Tecords ri > establishes Neolithic ir polished ttery far ex- work of their Dog ani ymestication sturdy civil y after this ght by dio ed for the 1 in the Ir struction d . By meats adio system of the insti- ‘ful results ead phones, in the table, master Ie he building. ifferent, the d by means ve different the amount have fourd eld for the mutes and earing. POPULAR SCIENCE MONTHLY Philadelphia’s New Giant Traffic Light 0 AID in han- T dling traffic,the City of Philadelphia has installed an en~ ormous searchlight of 300,009,000 can- dlepower in the tow- er of the City Hall. There it commands Broad Street, which runs for a distance of 12 miles, one of the longest straight streets in the world, controlling straight- ahead and cross town traffic by its signaling beams. The light is 30 inches in diameter. America Has a Monopoly on Severe Tornadoes ORNADOES, such as the one that _™ left a path of death and destruction in northern Ohio this summer, are practi- cally an American product, according to Dr. W. J. Humphreys of the U. S. Weather Bureau. This type of storm is very rare in other parts of the world. The middle Mississippi Valley is the region where they are most prevalent. They are very rare in and east of the Appalachian Mountains, but are known in every other part of the country east of the Rocky Mountains. The exact conditions productive of tornadoes are not known. It has been ob- served, however, that they most fre- quently occur in the southeastern part of large circular storms. Just as cross currents produce whirl- pools in swiftly moving water, so torna- does are produced by cross currents of Wind. The waterspout observed over Lake Erie during the Ohio storm was merely the tornado passing over the water. The only difference between a waterspout and a Kansas twister is that the whirling winds are passing over water instead of land. re Above: Operating the giant searchlight from the tower of City Hall, Philadelphia, to signal traffic on Broad Street, shown at left Testing Waterproof Paper ATERPROOF papers now’ are tested by means of ground glass. | The paper is folded into a small box | filled with water, and placed on the glass. } The glass rests on a dark surface with the ground side uppermost. If moisture goes through the paper, it’ makes that part of the glass transparent, producing a dark contrast. 77 U.S. Perfects Instrument to Test Brakes HE United States Bureau of Stan- dards has perfected a device known as a ‘‘recording decelerometer” for accu- rately measuring the braking ability of automobiles. In the past, such brake tests were made by measuring the stopping distance on a road, determined by a line at which the operator applied his brakes and the final position of the car. This method led to inaccuracies. The new method consists of mounting a weight on the end of a stiff, flat spring, and connecting this weight with a pen recorder. The action of the instrument exactly parallels that of a passenger, in that when the car is retarded, the weight tends to continue in the original direction. The more violent the retarding force, the greater the movement of the weight. Tests with the new instrument indicate that deceleration is practically inde- pendent of speed; that a clean wet street is no more slippery than a dry one, and that four-wheel brakes are apt to be more than twice as effective as rear- wheel brakes alone. _ Why Forest “Openings” Remain Treeless HE United States Forest Service has been conducting tests to ascertain why trees don’t grow in the grassy open- ings in the midst of excellent pine forests in southeastern United States. It was found that the fine soil deposited from' neighboring’ elevations’ remains saturated with water until late in the spring, causing the seed to rot before germinating, or the seedlings to “drown” for lack of air. Should seeds get started, they perish later in the summer, when the soil bakes exceedingly hard and there is no available moisture for the roots. Phese open areas also are exposed to the full sweep of the winds. ee 4 se Coe - pos ce ee wept weet ik ee SR MR Hee PR ge UT tena sh a ’ A treeless opening in the midst ine forests, showing government soil-testing apparatus 4 4

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78 Collapsible Scissors Fit in Pocket Case The scissors in use F ALL the tools that come into every- day use, few are more serviceable than scissors. Probably the chief reason why more people do not carry scis- sors about with them as they do pocket knives is that usually there is no shield for the blades and sharp points. To meet this need, collapsible scissors, which, when folded flat, fit into a small metal tube, recently have been invented. Even the loop handles for the fingers are collapsible. The carrying case is fitted with a small ring so that it can be attached to a chain. It can be carried, conveniently, in a man’s pocket or a woman’s hand bag. POPULAR SCIENCE MONTHLY New Insulating Brick Saves Costs O SAVE costs of hauling, and of mortar, a new combination brick recently placed on the market is designed to serve both as a face brick and a Pie-Maker Turns Tin Cans Into Profit A CHICAGO * * pie manufac- turer has turned waste into profit by the perfection of this electric ma- chine that flat- tens used fruit cans so that they ean be sold in car- load lots for the manufacture of window weights. The cans are mashed by a heavy weight that is raised and dropped by means of gears. there? OWNS OS 12. How Much Science Do You Know? VERY day, whether you realize it or not, science is lightening and making more effective the daily labors of all of us. In the home, in the office, in the factory and workshop, a working knowledge of the principles by which science can be usefully applied is becoming more and more important to our success. Below are a dozen simple questions about scientific facts that not only will help test your knowledge, but will afford you real enjoyment. Answer them as best you can, then turn to page 159 for the correct answers and see how nearly you were rizht. Another test of 12 questions will appear next month. 1. How many muscies are there in the human body? 2. What is our solar system? How many planets are 3. What are electrons and what is electric current? . Why do soldiers break step when crossing a bridge? Do we get a pound of ice from a pound of water? What is the difference between soil and rock? Why is copper used for electric wires instead of iron? . What is horsepower in scientific measurement? . What is the purpose of our eyelashes? 10. Why is gasoline more e 11. Why does drinking alcohol make yoii See double? Do animals laugh? Give the reason for your answer. xplosive than kerosene? + common brick. It has a facing on one side and an unfinished surface on the other side. It is said to weigh only seven-tenths as much as the brick it replaces, thus saving freight and truckage costs. Its makers claim also that less mortar js required to lay it. Efficient insulation against heat and cold is provided by two horizontal dead air cells and a central closed air cell. The brick is of the Standard size. Sewing-Machine Case and Table Combined O PROVIDE a substantial base for the portable electric sewing-machine while serving as a decorative article of furniture, a collapsible sewing-machine table has been devised. When open, the machine is held rigid at the most convenient height for sewing, and the leaves form a handy sewing-table. When closed, it has the ap- pearance of a small cabi- net, and serves as an attractive case for the machine. How the sew- ing-machine table appears when unfolded Send for List of Approved Products PopuLaR SCIENCE MONTHLY will be glad to furnish, upon request, a list of radio and tool manufacturers whose products have been tested and approved by the Popular Science Institute, of Standards.

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ts ¥ On one > on the 2n-tenths ces, thus sts. Its 10rtar is eat and tal dead ell, The > and base for ‘machine rticle of machine eld rigid nvenient ng, and a handy When the ap- all cabi- 3 as an for the ducts will be list. of whose yproved ute, of Demountable Bodies Save Freight Charges POPULAR SCIENCE MONTHLY a ™ : i ELIMINATE a great deal of expensive handling of freight ship- ments in less than carload lots an effi- cient system was recently introduced in Cleveland, Ohio, by using demountable freight bodies of moderate size. These were distributed to freight houses throughout the city, each one having a certain route to take in going from one station to another. When the boxes were filled they were loaded on trucks provided for this pur- pose. These then transported the bodies to their proper freight stations, where the contents then were unloaded directly into proper freight cars with a minimum of labor. The new system resulted in a saving of much space in the freight houses, as well as a lessening of switching of Miniature Clothesbrush Fits Pocket or Bag ew A TINY clothesbrush is a novelty that will be found very useful. It fits in any pocket or small handbag and serves as an excellent article for removing dust and dirt in an emergency, especially when traveling. A small case is provided to keep the bristles of the brush in good order and to protect them from dust and dirt. DODIIT ARB COIFNGCE freight cars, which was done away with by truck transportation. The photograph above shows workmen unloading boxes from three of the de- mountable freight bodies after they have been hauled to the freight station. 79 Pocket Pruning-Shears Is Useful Gardening Tool aati prun- m ers for trees 4 and shrubs form a very convenient gardening im- plement. The metal handles are collapsible and the blades fold back into the handles when not in use, so that the closed article resembles a penknife that slips easily into the pocket. For all its light weight, the implement is sufficiently strong. Wuy are some woods more durable than others? That question is answered by investigators at the Forest Service laboratory at Madison, Wis. They find that woods that last contain substances that when extracted by water are poisonous to the forms of bacteria and wood-destroying fungi responsible for wood decay. These toxic substances are more abundant in the heartwood than in the sapwood. Attachment Gives Electric Shave and Massage SMOOTH ane non-irri- tating shave is the advantage claimed for a mechanical attachment that transforms either a safety or straight- edge blade into an electric razor that makes the blade vibrate. By inserting a mas- sage attachment the instrument also can be used as a vibrator. NCE in a while the clutch on your car will refuse to disengage. This trouble, which may have serious consequences in crowded traffic, is commonly known as “‘sticking.”’ In a cone clutch it is usually caused by abuse of the mechanism; in a multiple disk clutch it is often due to the fact that the oil supply has been neglected or that the oil has become congealed. To remedy the condition, do not try to throw out the clutch by force, but throw your gearshaft lever into neutral position and coast to a stop at the side of the road. If the clutch is of the cone type, it will soon release itself, after its leather surface cools off. If it is a multiple disk clutch, the application of kerosene or gasoline will limber it up. Kerosene is preferable. Know Your Car When the Clutch Sticks If, in a cone clutch, relining is neces- sary, new lining obtained from the manufacturers of the clutch is prefer- able, because of convenience and ac- curacy. If not obtainable, however, new lining should be cut, using the old as a pattern. It should be much thicker than the old lining. In putting on new leather lining, it is important to see that it fits tightly and true to the cone. Neatsfoot oil should be applied frequently to the new leather while it is being worked in. In a disk clutch, if the plates are not too badly worn, they may be re- faced; otherwise new plates will have to be installed. If the disks are sprung or grooved, new ones will be necessary, and they should be obtained from the manufacturers of your car. MONTH V

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80 POPULAR SCIENCE MONTHLY Useful Ideas for Home Convenience ME a > Household economy is represented in this permanent broom handle and _ holder. When one broom ‘ 4 wears out, a new one VEER N A labor-saving jar opener consists of a cable, is inserted in the 4 BN AAD latch, and cog handle. The cable is placed holder and fastened eal Ne around the cover and tension applied by lever Under the lid of this glass “I jar is a mineral salt pad labo that absorbs moisture, worl preserving the crispness of theit food in the jar, such as salt, crackers and cereals This anti-tannin teapot is placed on its side while the tea is drawing. When upright, the leaves are kept separate and the brew is more wholesome A collapsible jelly bag is held by a metal rim supported on four folding legs that fit over the edge of the kettle By an ingenious ratchet ar- rangement this mop can be wrung simply by pressing a button and turning the handle. When buttonis / released,themopunwinds / Lifting hot plates is made easy with this nickeled holder, the prongs of which fit over the plate edge da br br un ov To prevent waste and assure cleanli- A knife and fork ness, paper napkins now are marketed This conve- combined in one in hygienic cardboard containers, nient knife f fe utensil is designed hi from which the napkins may be sharpener consists of two sets of cutting ; especially for salads. de withdrawn one at a time, either disks of high grade steel, between which i One of the side prongs in folded or unfolded, as_ desired the blade is drawn with short strokes is a small knife blade

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glass t pad sture, ess of ch as ereals fork one igned alads. rongs blade POPULAR SCIENCE MONTHLY s1 You Can Save Your Wife 10,000 Steps a Day estate dealer in suburban homes why most of our American houses sow were being built much smaller and more compact than they used to be, and ysually on little plots. “Js it due entirely to higher costs and increasing land values?” | inquired of this oper- itor who last year sold homes valued at upwards of $5,000,000. “Higher costs are play- ing their part,” he ac- jnowledged, “but really the most important fac- tor, I believe is the closer application of science to building, especially in the matter of built-in features to take the place of furniture. “Built-in furniture and labor - saving devices, worked into the house in their proper places by good architectural plan- ning, conserve space, Houses are being made smaller, partly in conse- quence. Less land is used because the auto- mobile has brought the world to our doorstep.” A FEW weeks ago I asked a real HAVE always advo- cated compactness and mechanical efficiency in the home, and was glad to find such strong support from a realty man whose business suc- cess proves he knows what the average man and his wife want in a new home. What he said about compactness expresses briefly the trend of prog- tess in American -home building. And nowhere is this development more marked than inthe modern kitchen. Built-in devices that save time, steps, and labor have done alot to solve the servant problem and to enable the woman of the house to take het proper share of recreation. Her work today is completed in about half the time and with far less physical exertion than that of our mothers and grand- — Husband and wife and children nefit, The predominant kitchen features to- ay are the built-in kitchen cabinet, broom closet, dresser, ironing board and breakfast nook. Other smaller built-in units include dish cupboards, cabinet wed the sink, and plate and cereal warm- : over the cook stove. Catalogues of rad makers of better-class woodwork Fier made it possible to replace special €"s with stock material, thus bring- ing the cost of obtaining the ideal By L. Porter Moore As president of the Home Owners’ Institute, Mr. Moore has helped plan thousands of small homes. His is valu- able “‘inside advice’’ for the thousands of American families who want econom- ical and attractive homes of their own. nities for errors in arranging and equip- ping a house. I know that scant con- sideration is given to these details, usually, until the planning is well along, and frequently, not before construction is under way. Then the “extras” begin. When a man . plans a house, without A compact, convenient kitchen such as this might save your wife as much as three miles of walking a day. The many cupboards and the breakfast table are stock millwork of the built-in type. Sink, radiator, laundry tubs, and range are properly located for the best ‘“‘routing’”’ of the work to save steps and labor. Notice the telephone in the corner for ordering supplies kitchen within almost everyone’s means. The importance of the kitchen in the modern home was indicated in a recent nation-wide house-planning contest. No two of the 6,000 plans submitted were identical. Nevertheless all of the ama- teur planners agreed on the funda- mentals of an ideal home, and chief among these was a good kitchen. The kitchen, said the judges’ report, was ‘“‘the most carefully studied” part of each plan, although the majority of contest- ants planned poorly. This contest in- dicated that while home builders today realize that scientific use of space in the kitchen makes a more livable home, most of them do not realize how to plan the details on paper. prRoM a special study of houses costing from $5,000 upward, I know that there are literally hundreds of opportu- consulting a woman, its interior arrangement is likely to be anything but scientific, or attractive. And without the assist- ance of a competent ar- chitect, or at least good architectural plans to be- gin with, both the man and the woman usually make a mess of many of the details. BY \ extras” I mean the charges thot begin to mount up against the home builder when the building contractor is called upon to make this or that alteration, or add details such as closets, built-in ironing board, garbage incinerator, package receiver, or electric outlets. Fre- quently several hundred dollars is added to the contract price for extras, because the details were not thought out care- fully, put into the plans, and contracted for. Yet most of the mis- takes in planning can be avoided. Thousands of steps—perhaps 10,000 a | REFRIGERATOR || STOOP ICE - DOOR a ae, PACKAGE [teed : ‘RECEIVER rf , a BROOM d KITCHEN eteceia CABINET a a. ey ar mF a KITCHEN HI we DRAIN 4 L eaig, SONE | 2 1 + HIRONING BOARD ([L— — eo} | e c vs GAS | 4 + rance |@ ©) = ° | > ee « © > wae 4 CLOTHES a 5 | CHUTE & cic He z z= — WRAP CLOSET LIVING-ROOM / 2 } , ¥ il Kitchen floor plan, showing an astonishing number of conveniences built into small space

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ae ae The dining nook for breakfast and other in- formal meals is one of the most popular of all the improvements of the modern kitchen, for it saves many an unnecessary step for the housewife. The use of stock woodwork makes it comparatively inexpensive to construct day—can be saved for the woman of the house, and actually years added to her life, by proper planning at no greater first cost. After the house has been built, some mistakes can be corrected easily, and cheaply. Others can be remedied only at an almost pro- hibitive cost. [N the preparation of three meals and performing the regular duties of housekeeping in a poorly-planned six or seven room house, a2 woman aver- ages more than 27,000 steps in the average day. That totals about eight miles! It has been determined that 76 per cent of those steps are in the kitchen. A well arranged kitchen, then, would be likely to save a woman a three-mile walk daily, for experiments have in- dicated that rearrangement of kitchen equipment, dining room, and hallways of the poorly-planned house reduces the housekeeper’s walk by two-thirds for the same amount of work. In planning the arrangement of fixtures and equipment in a kitchen, the work incident to preparing meals first should be ‘“frouted.”” This means that before- meal work must travel along a definite, well ordered path. Poor location of the stove, sink, the outside-icing refrigerator, the package receiver, and various cabi- nets may spoil the convenience of the whole workroom. In this mapping out the work-room, the individualities of the housewife for whom it is prepared are an important consideration. Some months ago a young real estate salesman came into my office, bemoaning the results of his day of handed.”’ POPULAR SCIENCE MONTHLY ineffectual sales efforts. the sink should be left open, to ““Of all the luck!” he access for the plumber when rep ejaculated. ‘“‘Why did needed. she have to be left- In planning the location of th “What did that have within as well as from without, go to do with your losing a furnace ashes, laundered clothes, s¢ sale?”’ I asked him. “We didn’t have a_ through the kitchen. If the grade house on the property is large enough, it often affords a equipped for a left-hand- _veient location for the refrigerator. At ed woman,” he plained. ‘“‘Everything in the outside, if possible. the kitchen—gas range, sink drainboard, built-in WHEN President and Mrs. Coolj ironing board cabinets— was located all wrong. House at Washington a year ago, they In addition, this woman paid a visit to the “Home, Sweet Home’ was taller than the aver- model house, the modernized replica af ageandtheregulation 34- the birthplace of the composer, John inch sink was too low. Howard Payne, erected for the 9}. Of course, we could have servance of Better Homes Week jy PTOVide alrs ate e base. ment steps, be sure they are handy from that Teens agged entry COn- or storm sash, need not be dr ex- any rate have the refrigerator iceq from ; : d were ‘‘settling’ in the Whit Washington. It was standing just bac; of the White House at that time. Thy Associated Press news dispatch, descrip. ing the visit, included the following paragraph: “They spent about fifteen minute going over the house and both asked many questions of attendants. The Presiden was particularly interested in the lighting and ventilating features. Among other things he pointed out there was m provision for icing the kitchen refrigerator from the back porch.” This defect was immediately remedied, I learned later, Every kitchen should have ample ar. tificial light above the range, the sink, the worktable, in the entry, at the head of the basement steps, and near the refrigerator. Where electricity is used, plenty of power convenience outlets must be included for the iron, percolator, toaster, washer, mangler or ironer, fan and other conveniences, at the points where these are to be used. In all planning one of the main points to bear in mind is the use of stock (Continued on page 143) Corner space never need be wasted in your small kitchen. Built-in broom closets like this, and corner dish cabinets of similar size and shape, with shelves for dishes, utensils, and food supplies, are stock productions that can be set into new or old houses put in another sink and changed around some of the equipment, but she found another house which pleased her almost as much as one of ours, and which had been built for a left-handed house- keeper.” Often mechanical details of a house must be altered to fit par- ticular cases. The woman’s height must be considered when the kifchen sink is ordered. The best position for the sink, by the way, is under a window, with drain- boards and cupboards preferably at both sides. The space below With the passing of the pantry, this type of cabinet has come into its own. Its scientifically desigm compartments, storage space and fittings er eatly re- duce wasted steps and efforts. Built-in and moveable designs of various sizes and costs are available

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to Provide Tepairs are f the base. handy from ut, so that hes, Screens © dragyed grade entry Ords a op. erator, At r iced from S. Coolidge the Whit. r ago, they veet Home” 1 replica oj Doser, John r the ob | Week in & just back time. The ch, describ. e following en minutes asked many ie President the lighting mong other Te Was no refrigerator | defect was ned later, e ample ar. , the sink, at the head d near the ity is used, yutlets must percolator, ironer, fan the points main points e of stock $3) of cabinet designed reatly re- moveable available POPULAR SCIENCE MONTHLY 83 Keeping Your Car Free of Carbon trouble, carbon is the most dis- tressing nuisance of motoring. No experience that I know of is more annoying than operating a car with car- ponized cylinders. It is difficult to start i, The motor becomes overheated quickly. It misses. It pounds and danks as though trying to shake itself apart on the slightest () eerste possibly, of chronic tire By E. B. Staples M®*: STAPLES, an expert auto- mobile mechanic of Eureka Springs, Ark., ts one of the regu- Jar readers of POPULAR SCIENCE MONTHLY. What he says here about carbon and its prevention is based on his years of practical experience as mechanic and driver. pass by even well-fitting rings and pistons —will cause carbon in the cylinders. These, then, are the principle causes of carbon. What are you to do to get rid of it? The simplest and one of the most effective ways is to scrape it out. If your car has a removable cylinder head, you can scrape the carbon from each cylinder with a putty knife or hills. It is sluggish and unresponsive on level roads. It consumes an enormous quantity of line. Driving such a car is a nerve-wracking and exasperating process. It js dangerous, too, for a car that will not accelerate immediately when the throttle is opened, is a poor ve- hide to which to in- trust your safety in an emergency. HERE are two things to do about carbon. One is to get rid of it if you have it; the other to take care that it doesn’t come back. Neither of these is especially difficult. Carbon deposits in the cylinders of a motor-car come from two sources—gasoline and lubricating oil. Both are chemical combinations of hydro- gen and carbon; hence, carbon is an essential constituent of each and cannot be removed from them if they are to fulfill their purpose. The carbon that comes from gasoline has a dull, sooty appearance and is likely to be deposited in all parts of the combustion chamber. Oil carbon has a glassy sheen, and, except in extremely bad eases, is likely to be found only on the tops of the pistons. The gasoline carbon deposits are due to incomplete combustion. If your car- buretor adjustment is too rich, if you are constantly feeding to your motor more gasoline than is necessary, carbon will be formed. There is no escaping it any more than you can prevent a lamp from wie e Ad oe es x ies similar tool. If you cannot remove the cyl- inder head, you will have to supply your- self with the scraping tools made especially for the purpose of re- moving carbon. These are operated through the valve cap or spark- plug openings. HREE such tools usually are neces- sary—one for the pis- ton head, one for the cylinder head, and one for the various curved surfaces within the combustion chamber. Scrape with each tool until it no _ longer scratches, but slides easily over the surface. Then with a bellows smoking when the wick is turned too high. In either case you are admitting too much fuel containing a great amount of carbon to be consumed in the available supply of air. Your motor will become carbonized from lubricating oil for a similar reason. If you have loose pistons, or poorly fitting piston rings that permit the oil to seep through to above the pistons, part of this seepage will be consumed, and you'll notice a bluish smoke issuing from the exhaust. But at the same time the un- consumed carbon, released from the oil during the burning, will be deposited in the cylinders. Too much oil—using an oil that in body and quality is not suited to your engine, permitting the oil in your crankcase to become so thin that it will CARBON FIG.| CYL. BLOCK / PISTON Ig u FIG.3 Figure 1 shows the points in the cylinder where deposits of carbon are most likely to collect. In Fig. 2 are shown the uses for three special types of scraper in scraping the piston head, Removing carbon from cylinders and valves with a newly invented electric brush of steel bristles, driven by a small motor through a flexible shaft - use of chemicals. the cylinder head, and the out-of-the-way cavities around and over the valves. After the scraping, the carbon should. be blown cut thoroughly with a hand bellows, as shown in Fig.3 blow the carbon dust out of the cylinder. This dust, carelessly left in the combustion chamber after scraping, will become red hot when you run your motor and will cause pre-ignition and carbon knocks just as if the cylinders had never been scraped. A substitute for scraping, recently in- vented, is in the form of an electric brush with steel bristles, driven by a small motor. "THE best known way of removing car- bon, however, is to burn it out with an oxygen torch, a method employed in service stations and garages. An oxygen decarbonizer is an expensive apparatus, however, and few persons except repair- shop mechanics have access to them. Another way of removing carbon that, I am assured, is very successful, is the Several preparations on the market, when poured or sprayed in the cylinders, are supposed to dissolve the carbon accumulations and to cause them to be discharged through the ex- haust when the car is operated. Still another method of fighting carbon with chemicals is by mixing certain powders or liquids, which are sold commercially, with the gasoline. These chemical prepa- rations are said both to remove carbon and to prevent its formation by chemical action in the natural process of consuming the gasoline. Among the newest of these preparations are boyce-ite and ethyl gas, both of which are said to have proved their efficacy in scientific test. Now, assuming that your car is free of carbon, how are you to keep it so? The first thing is to make certain that (Continued on page 156)

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\ , J HY are wabbly wheels so preva- lent? It is easy enough for one driving along the road to see the other fellow’s wheels, but it happens very frequently that a man will drive for months before he realizes that his own are out of line. At times the wear on the tires is so slight and gradual that it does not show; but it may be detected by the sharp edges on one side of the tread pat- tern. Run the hands across the tread pattern from each side. If there are sharp edges, they will be felt. In alining front wheels, the first step is to loosen the tie-rod bolt-yoke at the end of the steering reach rod and remove it as shown in Fig. 1. Since these yokes are clamped to the threaded portion of the reach rod, it will be necessary to loosen the clamp bolt and then turn the yoke on or off, depending on the amount and the way in which the wheels are misalined. In at least one case, right- and left-hand threads are used: and the adjustment is made by loosening the yoke - clamp bolts at each end and then turning the reach rod. The center of the tire must measure from Y{ to 3¢ in. closer at the front than at the rear. Set eo > the wheel on a jack Fig. 4. Two nails aid and mark the cen- in grinding valves ter of the tire by holding a soft lead-pencil against the tire as it spins. Measure with a stick. When the proper alinement has been secured, the tie-rod bolt is cleaned and replaced, the cotter key inserted and the clamp bolt locked tight. Regular in- spection is essential for maintaining front wheels in proper alinement. Dh ghe of the cheapest and most efficient means for locking a Ford car is shown in Fig. 2. First, get two small strips of copper, bend these in the shape of a shallow U with an inch left flat at each end. Then punch holes in these flat ends and screw them on the under side of the floor boards. Be sure and leave only enough space between both strips so that a common eightpenny nail will touch them when inserted between. One of these strips is connected with a wire to the magneto binding post and the other is grounded. When the nail is placed the current can flow through the circuit; but when the nail is removed, the electri- eal circuit is broken and it would take some time for a thief to find the trouble. HE troubles incident to connecting the universal joint of a light popular type of car can be overcome to a large ex- tent by the simple expedient of connecting the brake rods to the hand-brake lever, ices that How the Motorist Can POPULAR SCIENCE MONTHLY TIE-ROD BOLT = WIRE TO ee TIE-ROD YOKE te td PLATES Fig. 1. Adjusting Fig. 2. Secret igni- the tie-rod yoke tion lock for Fords eee, PRESSURE ON BRAKE LEVER . PULLS AXLE ASSEMBLY FORWARD Fig. 3. Assembling the Ford universal REAR BOW OF TOP ° SCREWEYES (FS =p |/ E y : WY, ROLLED-UP SIDE CURTAINS Fig. 5. Keeping curtains out of harm’s way as shown ¢f—) ¢-—3mm in Fig. 3. W ork screap-iRoN JAWS-f 18 ing on the forward & oa region of the car A |__APIPECOUPLING nq over the uni- Gheghe. —_ versal joint, it is most in- conve- Fig. 7. A homemade nient to bring the spring-leaf spreader axle for- ward when en- tering the squared end of the universal and holding the axle in position while inserting the connecting bolts. With the brake lever connected with the axle assembly, the worker, singlehanded, easily can pull the axle assembly forward and hold it in position. In spite of its simplicity, this suggestion has not been widely practised, possibly because it is known only to a somewhat limited number of mechanics. The in- dividual owner will find this method well worth adopting in the course of repairs that involve connecting the ever trouble- some universal. y= valve heads are provided with holes instead of a screwdriver slot, the method shown in Fig. 4 can be utilized while grinding them. Two nails are inserted in the chuck of a hand brace, Cut Garage Bills Save Time and Money the heads having been cut off previously The nails then can be spread to provide any hole centers, while the chuck wil] hold them in position so that removal becomes quite simple. A CONVENIENT method of carrying Ford side curtains when they are not in use is to hang them up in the corner at the back and close to the top, as in Fig. 5. Place three screweyes in the wooden cross piece and secure to each of these a piece of rawhide belt lace by tying it in the middle. The curtains are then neatly rolled up and tied as shown in the illustration. This keeps the curtains in much better condition, and they are always handy when wanted without dis- turbing the occupants of the rear seat, AIN-WATER or distilled water should be used in the storage battery. For some autoists it is not always convenient to obtain distilled water. One way to collect rain-water is to place a large glass funnel in a milk bottle and set it out on the lawn (see Fig. 6). The water should not come in contact with any kind of metal and it is best to wait for a half hour or so after the rain starts to get the cleanest water free from dust in the atmosphere. The bottle, when full, must be kept sealed to prevent dust or dirt getting into the water. PAILURE to lubricate properly the springs of an automobile causes the spring leaves to rust, or ‘‘freeze,”’ together, which results in annoying squeaks and spring breakage. The device shown in Fig. 7 will spread the leaves of the springs far enough apart to permit the insertion of lubricant. Each of the spreading jaws is made of strap iron bent as shown, with the ends ground down to a wedge shape. The blunt end is bent around so as to butt against the back of the wedge and act as a support. A clearance hole for a 34-in. bolt is drilled through the jaws with a distance, A, sufficient to allow the spreader to reach over the maximum thickness of the spring to be lubricated. Pipe nipples placed as shown serve as braces to keep the sides from buckling when the nut is pulled up. To use the spreader the wedge ends of the jaws are placed between the spring leaves on either side and the nut tightened with a wrench until the wedges pry the leaves apart. The best lubricant is a mix- ture of graphite and cylinder oil sti into a thin paste and applied with the blade of a knife the full length of the spring leaves. Fig. 6. Gathering rain- water for the battery arou shop hous shel mak fixin kidd nish with amt to 1 cab 100 “ of 1 hav det Mc pie tai wil

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Is oney viously, | Provide will hold becomes Carrying they are 1€ corner P, as in In the ) each of by tying are then m in the ‘tains in hey are out dis- eat, water storage or some is not venient distilled > way to n-water a large el in a and set he lawn ). The ild not contact kind of t is best > a half fter the to get t water . The aled to > water. ‘ly the ses the gether, ks and spread h apart . Each ‘ap iron d down end is he back ort. A drilled 1ce, A, o reach 2 spring aced as 1e sides lled up. ends of | spring zhtened pry the $ a mix- stirred ith the of the POPULAR SCIENCE MONTHLY Valuable Hints on Furniture- Making for Beginners tions are much the same asmine. I like to putter sound my little cellar work- sop. Doing the necessary house repairs, putting up shelves, easing cranky doors, making and repairing screens, xing up toys and kites for the kiddies, and painting and var- nishing—these are a real hobby with me. But they don’t sat- isfy altogether my workshop ambitions. I’ve always wanted to make furniture or put up cabinetwork fit for the living- room. “That’s where the real sport of making things comes in,” I have said to myself many a time, when looking at furniture details in POPULAR SCIENCE Montuty. “It must be fine to carry through one of these pieces, one step after another, as time permits, with the cer- tainty that the finished work will be worth while.” Pin ar your inclina- AND I have pictured myself saying casually to a vis- itor, “Oh, yes, I made that smoking-stand. It’s walnut. Notice the choice figure of the wood in those door panels.” Ihave more than one friend who always has something like that to show and say, but they are all good workmen or have had the benefit of considerable manual - training instruction. That’s where the difference comes in. I know next to nothing about cabinetwork. Whatever knowledge I have of woodworking tools comes from the trial-and-error sort of ex- perience that so many amateur mechanics have; and, besides, Thave only a small kit of tools —just the average outfit. It so happens that the Home Workshop Editor of POPULAR SIENCE MONTHLY commutes ‘0 New York from the same ‘uburban town as I do, so I marked to him _ several ‘tonths ago on the predicament it workers like myself who vould like to make worth- vhile furniture and yet haven’t the time, tools, nor knowledge. (Continued on page 114) By Edward L. Munson -— — 18"——— VENEER. STRIPS COVER, FRONT EDGES OF CASE: BROWN ENAMEL MAY BE USED INSTEAD TOP VIEW CORNER OF STAND “aBOTTOM SY END Wo RAit : i t 4 CENTER STRETCHER ~— OVERLAYS | BOTTOM | END RAILOR STRETCHER FRONT CORNER 2 SQUARES OT 2 y 4 LA | ; Ve SQUARES OVERLAYS ¢ 7 7 THIN \WAL.OR MAHOG. VENEER. GLUE ON PAPER BEFORE CUTTING WITH FRET- OR. COPING-SAW. DETAIL OF [ LEG INTERIOR OF CASE TO BE FITTED UPTO SUIT RADIO RECEIMING SET USED J SIMPLIFIED RADIO CABINET IN WALNUT OR MAHOGANY WITH OVERLAYS, TWO-TONE FINISH A PROJECT FOR THE BEGINNER, IN WOODWORK _.

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86 HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY How to Construct an Upholstered. Footstoo| HE making of a stool similar to either of those illustrated is an enjoyable pastime, and the fin- ished product will find a useful place in any home. Few tools are required and the cost of materials is reasonable. The construction of each design is made clear in the working drawings below at the right. Design No. 1 requires a mor- tise and tenon joint in each corner. The section AA shows that the tenons must be mitered or cut at angles of 45 degrees and that a space is left between the tenons where they meet in the mortise. If the first design is chosen, the rails may be made of any soft wood, as they will be entirely covered when finished. The soft wood is much easier to tack into. The legs should be made of some wood that will take a pleasing finish. Oak or black walnut are very good, but if you cannot obtain these, a piece of yellow pine 2 by 4 by 18 in., ripped down the center, and cut in two crossways, will provide four good legs. These should be well sanded and an oil stain used. Should you decide to make a stool similar to Design No. 2, it will be neces- sary to use the same kind of wood for the rails as for the legs. Figure 9 shows the reason for this. A doweled joint is shown in the corner construction for this stool, but a mortise and tenon could be used if you prefer. In laying out a doweled joint, always work to center lines and use a very sharp, hard pencil or a knife for marking. You will find it of great aid in securing accu- racy in such a layout to place a leg and rail in their relative positions in the vise FIG.1 STUFFING REGULATOR; Steps to follow in upholstering a stool, and details of stretcher and stuffing regulator or a clamp and mark for all four openings before taking them apart. The curve for the rail should be drawn on heavy paper and transferred to the wood after it has been cut out from the paper. A coping- or scroll-saw should be used to make the cut, taking care to hold the saw-blade square with or at By William T. Weld Shopwork Instructor, Peoria, III. F YOU have been avoiding up- holstery work because you do not know how to do it, you will find this article most helpful. It is the first of a series prepared especially for Popular Science Monturiy by William T. Weld, an expert on this subject. Next month he will tell how to make flag or rush chair seats. Trimming an upholstered stool with fur- niture bind- PONG ing or gimp th yf y vi right angles to the surface of the rail. The upholstering of both stools is the same with the exception of the final covering and the binding. In the case of Design No. 1, the gimp or binding used as a finish continues around the inside of the legs (Fig. 7). In No. 2 no gimp is used. The final covering is carefully fitted around the legs, drawn down to a straight line on the rails, and tacked as in Fig. 9. After the frame has been built, it should be thoroughly sanded, given a coat of stain and two coats of good var- nish, and allowed to dry in a dust-free room. You are then ready to begin the upholstering. There are several kinds of webbing on the market; but for our purpose the 3 !4- in.-wide, close weave should be chosen. About 2 yds. will be required. The inner edges of the rails should be filed or sanded a trifle before the webbing is tacked, as this will prevent its wearing through in use. Figure 1 shows how to begin. Let the webbing project about 14 in. toward the inside and drive in three 10-oz. tacks, keeping the outer ones about 3/16 in. from the edges of the webbing; then fold over as shown and drive in three more tacks at places that will just miss the lower ones. This same method is used in all cases. 6 webbing is stretched as shown in Fig. 2. The end then is cut off about 1 in. beyond the rails, folded back over the first tacks, and tacked again. The weaving is shown in Fig. 3. The stretcher may be made of any scrap wood of the size shown. This stretcher also serves as an effective clamp in holding the rails to the legs while the glue in the joints is drying. Next, you should cover the webbing with burlap. Cut a piece larger than the stool frame—about 114 in. should project beyond the edges of all four Tack this in place with a few 4-oz, ¢ Cut out a square piece at each ¢ and fit the burlap around the legs, Take some of the material you are to use for stuffing and make several rojj; of it. These should be rolled quite tighti, and when finished would be of a diam. eter slightly larger than a pencil. La. these rolls along the edges of the rail; and turn the projecting edges of the burlap back over them (Fig. 4). Pyg, the roll out to the edge of the rail ang holding it in place under the burlap, drive in tacks all along the edge. Take care not to let this rolled edge project beyond the face of the rails, as this will spoil the appearance of the covering when it js put on. This edging will protect the final covering from wearing through. Corner blocks made as indicated anq having their outer edges rounded a little next are nailed in place in the corners with a few small nails. (A, Fig. 4.) These blocks should fit snugly against the two inner faces of the legs. They form a place into which tacks may be driven when making the turn around the legs, Any stuffing such as moss, tow, curled hair, or excelsior may be used. Tow is inexpensive and makes a good job. Make a pile of it about twice as high as you want the final shape to be. One pound usually is enough. Spread it out evenly over the burlap, being careful to remove any hard sticks or lumps that it may rails, acks, orner : wt SECTION A-A. “4 iS = 3t agRAD 1 ae ‘ 1 "he ' & 1 1 rE as + Boy DESIGN NO] Wy Se * ye 1 pA } @ ye dah apn aR h CORNER BLOCK A a (SEE FIG.2) FIG.7 | ee Working details of two types of stools, and methods of applying the top coverings contain. Only a smal! amount should be put on the corner blocks. ; Next, cover the stuffing with muslin, beginning on one side rail by turning the muslin under about an inch so as t0 tack through two thicknesses of materi (Continued on page 127)

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‘0ol four rails, 02. tacks, ich corne, PRS, YOU are to veral rolls lite tightly of a diam. neil, Lay | the rails €S of the 4). Push @ rail and rlap, drive ake care et beyond l spoil the rhen it js ‘otect the ough. cated and ed a little rners with .) These t the two y form a be driven the legs, wW, curled . Tow is b. Make h as you ne pound ut evenly s, and erings should be . muslin, turning so as to material HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY 87 A Roomy Filing Cabinet for Your Papers built to fill the need that sooner or later every man feels—the necessity of having plenty of room to keep ,is papers in an orderly manner. The material cost $10, so that, T* filing cabinet illustrated was By Edwin M. Love Simplicity and low cost are features Ly of this cabinet —— 2-4" 4 in comparison with the cost ofa commercial cabinet, the juilder was well paid for the time expended in construct- ing the piece. ; The novel joining of rails and posts commends itself for simplicity and strength. The four corner posts are of sock fir, 2 in. by 2 in., sur- faced four sides; but the actual dimensions are 114 by 114 in. Cut these 4 ft. 9 in. in length, and select the two best adjacent sides of each, marking them for face sides. Lay off the two front posts according to dimen- sions given in the elevation, and cut mortises 5g in. deep by 34 in. wide to receive the ends of the rails. Be careful to make the two in pairs, keeping the mortises back \ in. from the front faces. Next, cut similar mortises in the posts for the top and bottom side rails, keeping them 3/16 in. back from the outside faces. Plow %-in. grooves %¢ in. from the side faces, making them 14 in. deep, and run- ning them from the top to the bottom rail mortises. The rails are 34 by 134 in. net by 18 in., plowed in the center of one edge toadepth of 14 in. Two pieces of 3-ply fir panel veneer 34 in. thick are cut to a width of 18 in. arid a length of 4 ft. 534 in., keeping them square and straight. Assemble a front post with the two rails, a piece of panel veneer, and rear post. Glue the ends of SLIDES | By X1% ORNER ey POSTS, . ne WAxk ~ r i eo | GLAS Mu eats "2 DRAWER RAILS AX 3 The com- pleted cab- inet and the lower part of the framework are illus- trated at the left. Above is a dimen- sioned front view and details of the corner and drawer construc- tion the rails and clamp the posts firmly over the edges of the veneer, afterward nailing through the groove from the inside sur- faces of the posts. The resulting panels are neat and substantial. Rabbet the inside back edges of the ve aenne Zk LEZ Py | LS ka» ' DRAWER FRON back posts }9 in. deep and 3¢ in. wide, to receive a back panel of veneer 2 ft. wide and 4 ft. 534 in. long. The seven front rails are cut 2 ft. 14 in. long. Six are dadoed 14 in. deep 2 in. from the ends, to receive the drawer slides shown in the sectional photograph. One is left plain. In assembling the side panels with the rails and the rear panel, glue all the rail joints and draw them closely together with clamps, nail- ing through from the inside. Cut the back rails between the rear posts opposite the front rails and nail in slides as shown, keeping the up- per edges flush with those of the rails.. Put in the center guide slides, keeping the upper edges 4 in. above the rails. Brace the bottom as in- dicated. The center muntin between the two small drawers is of the same material as the rails, and is toe-nailed to the top and second rails. Build the drawers in the usual way by rabbeting the sides into the ends of the fronts. Use 34 in. by 6 in. tongue-and- groove pine drawer bottoms in grooves made 4 in. from the bottom edges of the sides. Nail guide strips on the bottoms. Enough clearance must be kept on the sides to allow of stops 14 in. thick being nailed to the front posts on each end of the drawer openings. The drawers, which close flush with the rails, may be divided by partitions to meet the individual needs of the builder. The glass drawer pulls are not put on until after the finish- ing isdone. The cabinet may be stained, shellacked, and either varnished or waxed, or it may be painted, as preferred. Cabinet Type Bench Made Cheaply from Old Washstand starting a home workshop, and it is reasonable to suppose that the owner wants to be as proud of it as of his tools. True, he might improvise one from a few planks, but the result would be neither pleasing nor altogether satisfac- tory. On the other hand, to build a pre- tentious bench requires another one for working up the stock lumber. There is, however, a way to build a compartment bench very quickly and at little expense. You will need a discarded washstand. If there is none in attic or cellar, visit a secondhand dealer, from whom you prob- ably ean buy one for about $1.50. Small defects do not matter, for they are easily remedied. First remove the drawers and towel- rack, The back boards, which usually are nailed on, should be knocked off carefully witha hammer. The screws retaining the top then are accessible for removal. A new top of birch or maple will replace the old one. If the washstand is about 30 y 17 in., as mine was, it will carry a bench top 414 ft. long, 22 in. wide, and 1% in. thick. The use of dowels will be necessary, as two pieces of plank will be A ssrine is the first requisite in By Austin G. Tribute ; hoe front view of bench (le f t) and the vise end (below) required to get the width. Glue doweled joint, and, when dry, smooth off any inequalities. Attach the new top. with substantial screws to. the frame of the washstand |} ¢ 27] . through the holes [2 == = = already there. Make slots in the back edge to hold try-square, gage, and one or two chisels. The next step is to estimate the height at which you can work best (have the top high enough) and add hardwood legs 3 in. wide and 1%in. thick. Screw them to the inside bottom corners. Then replace the back boards and drawers and renew broken knobs and hand-pulls. If the bench is not firm enough for work that requires heavy planing, it can be braced with diagonal strips across the back or otherwise reinforced where necessary. As for a vise, the kind will depend on the sort of work that interests you most. By way of suggestion, the old-fashioned screw vise is cheap and rugged. The screw and wooden handle cost a little over a dollar. The two jaws generally are made of 2-in. oak, although birch was used in the one illustrated. The outer jaw reaches downward almost to the floor, while the other may be short, secured to the bench top with bolts and supported by an end piece. In order to hold the outer jaw parallel to the inner, the device shown is used. A (Continued on page 122

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HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY Craftwork Holders for Gongs and Chimes 5 Yq HOLES i Ya" APART e868 “ 5-6" SHELVES — oO TENNONS E MORTISE FIG.1 ae ee , we a Hf +5 4" MORTISE CLEAR THROUGH ses : f— 15" re = ‘ ¥. Po -5 4 ' ‘+ my t rar MORTISE 1 : { ‘J ' nt 1 : iy ! ' o ' y , ” n » | G ' q 47a 1! Nall | ' a tye ‘4 ' I Laie 434 Ai]; | EF ; mn”) h iz ' i: | I ; i {fe - ‘4 ~ x Ws 12% 2s i L mS) ON Gal Tc SO of ss “ wide i . le BAL Re ny in | eae) J ; 1 ' | R54 ra t : ' | -t ' ' t a 124 I i) tt t ' , \ 1 ‘ 1 |i ! | \ { : : BEVELAND || | | § ' MORTISE { MORTISE ' Ly ! x ' . est yee, \ wy t GG aA di fad | Pa el |G TENNONS Dt w24 J By J. T. Garver home workshop. answer the purpose well. planed and sanded well. The gong shown in corresponding holes in the two uprights, A. Ordinary tube-phones are adapted to this purpose, and a tune may be played upon them. The uprights A are each 5 ft. 6 in. long, at the top. The base pieces, 214 by 15 in., are beveled back on the under edges 214 in. from each end, making them 114 in. wide inside. They also are mortised 2 in. from the ends, but not clear through, to take the corresponding tenons cut in the cross rungs, E, which are 34 in. square and 8 in. long, not including the tenons. HE base pieces and the cross rungs are; glued and pinned together and fas-} tened to the uprights with glue and long screws from the bottom. i Shelf C, 5 in. square, and shelf D, 4 in! square, are beveled to suit the slant of th uprights and are fastened to them with angle brackets and screws at distances o 2 ft. and 3 ft. 4 in. respectively from the bottom. The ornamental spanner at the top; from which the hammer is suspended with a chain or cord, is of brass or copper and is fastened with 4 round-headed -in. screws. The holes for the brass tubes should now be bored. Carefully mark on each originality, the Dutch craftwork dinner- gong mountings illustrated are interest- ing and unusual pieces for construction in your QO’ CHARACTERISTIC sturdiness and Oak preferably should be used in building them, but soft woods, such as pine, poplar, cypress, and chestnut of selected grain, will The stock should be A clear, sound board 34 by 12 in. and 14 ft. long will allow for some waste in the construction of any of these pieces. Fig. 1 is made by mounting a series of brass tubes of different lengths and tones with felt bushings through tapering from 8 in. at the bottom to 4 in. ' ca won --p 20” i : bottom, J J} the top. Four styles of simple sup- ports to hold ornamental dinner gongs or chimes side, beginning 114 in. from the top, and bore 34-in. holes straight through and across the uprights. Make the holes 114 in. apart. Chamfer off all edges and, after the stain and finish have been applied, insert the bushings and tubes and hang the hammer. The upright, A, of the gong holder in Fig. 2 is sawed from wood 7%{ in. by 5 ft. 5\4%in. The pieces B, each of which is 314 in. wide at the three widest points and 3 ft. 61% in. long, are fastened with screws and glue to A. The upper shelf, 734 in. square, is notched 1% in. on two sides to make a flush fit with the outside of A. The three lower shelves may be either round or octagonal. They are 5}4 in. in diameter. These shelves are pushed into their places and need no further fastening. The base, C, is made by halving at the center 2 pieces similar to those used for the base of the stand in Fig. 1, and is fastened to the uprights with glue and long screws. The gong is suspended with an ornamental screweye and chain. Figure 3 is an assembly of 9 pieces of the dimensions and shapes indicated. The mortise and tenon joints are well glued and those at E are pinned as well as glued. The upright A is 11% in. wide and 5 ft. 314 in. long, beveled and mortised 114 in. at the bottom to fit tenons in the base pieces B, which are 214 and 1} in. wide at the wide and narrow portions, and 8 in. long. Piece A also is tenoned at the top to fit a mortise in C. The ornamental bottom block, D, is 5 by 6% in, the upper block J is cut from a piece 6 by 67% in, These parts are mortised for the upright, F, which is 34 in. square and 5 ft. 45% in. long, not including the 34-in. tenons at each end. The upright, G, is 11, in. wide, except at the where it is 214 in., and 5 ft. 45¢ in. long. Allowance should be made for the 34-in. tenon at The cross bar, C, is mortised for A and G, the mortise for A extending clear through so that the ornamental top H can be tenoned into the same hole, The top H is 214 by 514 in. over all. In Fig. 4 is a small mounting for either tubes or bells. The over-all length of the board is 20 in. and the width runs from 8 to 12 in. Making a perfect glue joint is not the difficult task many amateur woodworkers imagine. It depends upon the fit of the parts to be joined and, of course, the grade of glue used, which should be the very best. RIVE the parts together before ape plying any glue, to assure yourself that you have a real joint. Do a little squinting and, if necessary, try the parts together a number of times until they shoulder up. Small brads are then driven in the glued joint and if conspicuous should be countersunk and puttied. All edges should be chamfered off before finishing the work. A brown Flemish wood dye is recommended, after which a light filler and a flat coat varnish, or wax, well rubbed, will bring out the fine grain of the wood and enhance the beauty of the lines. The gongs or tubes may be obtained at or through any city supply house. | The charm and beauty of these pieces will be appreciated by the builder who conscientiously applies his best efforts and ability, thereby molding into his finished work a lasting usefulness and an individ- uality all his own.

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. at the hich are vortions, 1 top to 6% in.; r 64% 8 in, which is ding the t at the in. long. enon at i and G, that the me hole, or either th of the ins from not the lworkers it of the rse, the 1 be the fore ap: yourself . a little he parts til they n driven spicuous od. ff before ish wood . a light vax, well in of the che lines. ‘ained at 2, se pieces der who ‘orts and finished individ- POPULAR SCIENCE MONTHLY If you have a hobby for making radio cabinets, furni- ture, work benches, porch swings, etc., you will find our Book invaluable for, naturally, you want to give your handiwork as beautiful a finish as possible. JOHNSON’S FREE--25¢ Book on Wood Finishing Tells You How To Radio Cabinets Seto «Sonne Finish This Book gives complete instructions for finishing all wood—hard or soft—old or new. It is the work of experts—beautifully illustrated. Gives covering ca- pacities—includes color charts, etc. Use coupon below. WOOD DYE (Penetrating) Johnson’s Wood Dye is very easy to apply. It dries in four hours and will not rub off or smudge—penetrates deeply, bringing out the beauty of the grain. Johnson’s Wood Dye is made in 17 popular shades as follows: No. 128 Light Mahogany No. 125 Mission Oak No. 129 Dark Mahogany No. 130 Weathered Oak No. 127 Brown Mahogany No. 110 Bog Oak No. 329 Red Mahogany No. 172 Flemish Oak No. 120 Fumed Oak : No. 123 Dark Oak No. 178 Brown Flemish No. 126 Light Oak No. 131 Walnut | No, 124 Golden Oak No. 140 Early English No. 160 Brown Oak No. 180 Gray All shades may be easily lightened, darkened or inter- mixed. Full directions on every label. Select the shade of Dye you want from the list above and order it from your dealer by name and number. 8. 0. JOHNSON & SON, Racine, Wis., U. S. A. “‘The Wood Finishing Authorities” Johnson’s Wood Dye is a dye in every sense of the word. It contains no finish whatsoever. Like most first class products it answers one purpose only—it dyes the wood —the finish must be applied over it. We recommend Johnson’s Varnishes or Johnson’s Polishing Wax. Ask for a FREE copy of the Johnson Book at the best Paint or Hardware Store in your locality. Stores dis- playing the Johnson Service Department Sign shown below can furnish the Book and full information on how to finish wood the proper way or use coupon. S.C. JOHNSON & SON, Dept. P.S.M. 10, RACINE, WIS. : SERVICE . “The Wood Finishing Authorities’’ Canadian Factory—Brantford DEPARTMENT , . ; F] Please send me free your Instruction Book on Home a Beautifying and Wood Finishing. I enclose 10c to 4 i cover postage and wrapping. ; MY DEALER IS...............-.--+++ssseeeee Oj a ET Te | 5 IN = 565 oo oii aces 8 : - Ci ROE GROG iio oii :k acess, 6:0 ove epnieniede diane ae j cee cee es Ss Se

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90 POPULAR SCIENCE MONTHLY ri Op i lethods ¢ How Expert Mechanics Save Time and Labor _ Machining Troubles and Their Remedy HE foreman gave me 24 bronze bushings (A, Fig. 1) and told me to bore, face, and turn them to the The cored hole at C was small, rather rough, and full of sand, sizes shown at B. as I soon found out when I put a tool into it. I held the work in chuck jaws on an engine Jathe and first tried boring out the hole with a tool like that shown at D. This entered easily and passed partway through until it reached a point it; DAVILA 4 WOLD TOIT Z “hihh i hiddbdli “SANDY CORE C By Albert A. Dowd Consulting Engineer CHUCK Vv JAY ‘je eel : ' on a mandrel. Although the bronze was hard and full of sand, the tool did not “erawl” up on the scale, because the shape of the point kept it in position so that the keen cutting edge was not subjected to wear. Since this experience, I frequently have ground boring tools in the same way with very satisfactory results when using them in cored holes, Long cored holes oftey are troublesome in _ pro- duction work, because the sand in the core acts as an x/) 5 = abrasive on the tool and about at E, where the edge Ys P soon ruins the cutting broke down so that I had eat eae? | wARRON A CHIP edge. If we attempt > SO that 1 ha ,. 8] AE i LAY hoa age. ve attemp to to take it out and regrind ets citi os SSA ; wi. drill a hole of this kind it. After regrinding, it cies ee a \ y | with a core drill, the tool stood up long enough to diagram at left, below E age has a tendency to follow finish the hole, but it Wi: 9: Miteinn 0 ee the irregularity of the hole, needed grinding again berias problem ier may be pre and if this runs out of true by grinding the DEF AI vented by shaping tool correctly TOOLPOS!) tools properly WORK TURRET HEAD te peeine fle foe er TOOL BG sod—=9 i) E ) ! ST SiDE HEAD gs - ox POS CORE = 2 FACEPLATE DRILL A T f Uy, il | FOLLOW REST _ WORK, EE B sation, | WORK Vg - (WORK a I SPECIAL JAW Fig. 3. gave incorrect results, after it had passed through all the way. I saw that this method would not answer, so I took another piece and after placing it in the chuck, I put a 9/16-in. drill in the tailstock and fed it through the work. The hole produced was very bad and the cutting lips of the drill were worn considerably from contact with the scale. Finally, I obtained another boring tool, took it over to a wheel and ground it differ- ently, as shown at F. After cutting and trying several times for diameter, I set it to bore the hole about 1/64 in. under size. This tool went right through the work, cut- ting freely, and the hole ap- peared to be very good. I followed it up with a reamer, which brought the bole to the proper size. Method of using a core drill that and the remedy once for all the 24 pieces. operations on the work are immaterial as they consisted only of turning and facing Fig. 5. Diagram that illustrates how chatter is caused and may be prevented in turning The boring tool required grinding only The other } a= qwioe D CHATTER MARKS .-... CHATTER sR MINT, PRONOUNCED, STOPPED ISHED™ Creer a Fig. 6. Diagram illustrating peculiar chatter caused in long shaft as the result of torsion slightly (as is often the case), hole will run out also. the resulting Hence, if it is afterward reamed, the hole usually will be slightly eccentric to the center of rota- | Old Bill Says:— | ORK without personal interest is drudgery. Unless you take real pleasure in your work, you never will know what real pleasure is. A simple rule for getting the right cutting speed and feed for any tool is to give the tool all it will stand without burning. | Always lift a file on the return stroke; dragging it dulls the teeth and scratches the work. iron. keep them together. Get the tool under the scale when planing or turning cast Hunting all over the shop for tools is waste of energy; tion of the work, though it may be correct as to size. I remember there was i! the shop not long ago 2 bright young fellow, who was an exceptionally rapid opera- tor on a vertical boring mill. This man had 50 castings to machine, as shown at A ip Fig. 2, and he was holding them by the inside of the rim in chuck jaws, as at B, 80 that he could bore, ream, turn, and face the surfaces C, D, E, F, and G in one set ting. The cored hole C ran out of truth more or less with the outside portion F and the (Continued on page 96)

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Ze Was ‘id not > shape hat the ‘ted to juently g tools th very ; when 1 holes. S often nN pro- use the iS as an 01 and cutting mpt to is kind he tool . follow he hole, of true patter rsion -esulting if it is ally will of rota- nough it size. . was in y ago a who was id opera- ing mill. stings to at A ip holding f the rim at B, s0 e, ream, surfaces | one set- an out of with the and the re 96) The Burglar was fussy, too “T hear Bill got robbed last night.” POPULAR SCIENCE MONTHLY “I'll say he did. He was supposed to go enti on a job today and took his tools home to get an early start. Somebody busted into his place, found the kit bag and picked out all the Starretts. Bill’s madder’n a wet hen, but he says you gotta hand it to the burglar, he certainly’ knows tools.”’ STARRETT INSIDE MICROMETER No. 124 One of the popular features of the Starrett Inside ““Mike”’ is the positive method of setting. Each rod is fitted with a collar by which it can be instantly and accurately seated in the micrometer head. The auxiliary handle allows the tool to be used in places too small for the hand, THE L. S. STARRETT CO. & World’ s Greatest Toolmakers—Manufacturers of Hacksaws Unexcelled ATHOL, MASS. se St Over 2200 fine Precision Tools for Machinists, Ap- prentices, Auto- Mechan- ics, Carpenters and other tool users fully described (pictures, uses, prices, etc.) in the NEW Sauar- rett Catalog. Get a free copy at any good hard- ware store or write us, Ask for No. 23 W.

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BETTER SHOP METHODS DEPARTMENT OF POPULAR SCIENCE MONTHLY How to Solve Milling Problems with a Universal Dividing Head milling machine is almost indispen- sable. ‘o most mechanics, but to the novice in he toolmaker’s art the use of the dividing |: ALL toolroom work the universal Plain milling work is familiar ead presents many difficulties. As a arge portion of tool work is accomplished vith the aid of the dividing head, it is ,ecessary for the toolmaker to understand horoughly the use of this attachment. The first and most important step in his direction is to study the construction »f the head and become familiar with the arts and their function. A dividing head is a milling machine ittachment used for indexing or dividing , piece of work into any number of livisions. Work of this character somes under two divisions, plain ind differential; and these are 0 sometimes subdivided into simple ind compound indexing. Both ‘lasses frequently involve _trigo- ,ometrical calculations, especially in aying out and boring holes in drill igs when the locations of these anoles are designated in degrees with relation to other working 0ints of the jig. There are many designs of lividing heads in use. These liffer only in the arrangement of yarts; the general principle is practically the same for all. They are made with a 40-to-1 eduction — a_ single-threaded worm engaging i 40 - toothed worm wheel mounted in a suitable hous- ng — and by neans of index jlates having vumbered = cir- ‘les accurately lrilled, it is pos- sible to obtain iny fraction ofa evolution of he main spin- alle. As the worm wheel has 40 FiG.! Divisions easily made with dividing head By H. L. Wheeler Machine-Shop Foreman plate is a pair of sector arms that serve as a guide in counting the holes and reduce the chance of error in counting. To explain the operation of the dividing head, let us suppose we are to cut a gear having 72 teeth—plain indexing. The work is mounted on an arbor between centers as shown in Fig. 3. The cutter is centered with the work and set for the proper depth of cut. The driving dog on the arbor must be wedged securely in the slot with setscrews so that there will be HOLES TO BE BORED FIG2 tables have been lost or destroyed, making it necessary to calculate the required number of turns. In any case a knowl- edge of how to do this will give a better understanding of the work in hand. Take the gear we have been discussing as an example. To find the correct index circle without a reference table, proceed as follows: Divide the number of turns required for one revolution of the spindle by the number of divisions to be made on the work. This will indicate the number of turns and fractions of a turn on the crank required for one division. To illus- trate: We have 40/72 = 5/9. Now we must select the index circle most convenient for this frac- 7 tion. The rule is to select a circle having a number of which the de- nominator of the fraction isa common multi- ple. Looking over the plates available we find 18, 27, 36, ' ————|_ any of which Fig. 3. Plain index- will do ing on gear work ss Photos courtesy Taking the Cincinnati Mill- 18-hole circle, meson multiply 18 by - 5/9 to obtain the number of holes the crank must be moved; then 10 holes on the 18 circle will index the gear 1/72 of the circumference of the circle or one tooth. In selecting the circle always take the lowest number when more than one circle is available, as this no backlash when the work rotates; this is important in all in- dexing work. The index pin then is set for the correct circle, which is ob- tained from _ tables provided with the seeth, it will be apparent that 10 turns of the rank will produce one complete revolu- sion of the spindle. All modern dividing neads are designed on this principle. Every index head is provided with one or more index plates, and special plates can oe made for unusual purposes. In addi- tion, it usually has a quick indexing plate attached to the spindle for obtaining all *ommon multiples of 24. * Most index plates are drilled with a series of holes on 6 circles of varying iameter, each circle having a different number of holes and known in shop par- tance as the “‘index circle.” Some makers, thowever, provide a greater number of circles on one plate, so that fewer plates are required for a given number of circles. Mounted on the same shaft with the Fig. 5. rise with the aid of a dividing head Milling a cam of uniform machine. If the cor- rect circle is not found on the plate that is already attached, it will be necessary to change it for a plate having the correct circle. Before starting to cut, make sure that everything is properly set and tight. To set the cutter for the depth, start the ma- chine and bring the cutter in contact with the work so that it just touches. Now set the vertical feed dial to zero, raise the table the required amount, and we are ready for the first cut. After the first tooth has been cut, the stop pin is withdrawn and the crank rotated the required number of turns to bring the stop pin to a new position. This operation is repeated until all of the; teeth have been cut. It sometimes happens that the index Fig. 4. The correct set-up for a typical job of spiral milling requires the smallest number of holes to move the crank. Set the sector arms to count 10 holes on the 18 circle and proceed with the work. Regular gear-cutting machines are built on the principle of the dividing head, ex- cept that the worm wheel has a greater number of teeth and the indexing is auto- matic instead of hand operated. CIRCLE can be divided easily into degrees or fractions of degrees. Fig- ures 1 and 2 are typical examples. The layout in Fig. 1 may be expressed as 6 equal divisions that are equal to 60 de- grecs each (360 degrees divided by 60). In this case we would follow the same pro- cedure as for the gear prob!em. Figure 2 is somewhat more complicated. In the first division we wish to move the spindle through an arc of 55 degrees. One complete turn of the crank is equal to 1/40 of 360 or 9; then, dividing 55 by 9, we have 6 1/9 turns to make, or 6 turns and 2:holes on the 18 circle. To move for the next 65, we calculate 65/9 = 7 2/9, or7 turns and 4 holes on the 18 circle. The same method is followed throughout. Spiral milling is a combination of move- ments in the head and the feed screw of the table. Figure 4 shows a typical job of spiral milling and the correct set-up. (Continued on page 104)

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rennin aking uired nowl- etter ssing index ceed turns indle de on mber 1 the illus- must nient frac- - Tule ict ing a S IOn » de- of nisa aulti- oking lates 2 we ’, 36, vhich the ircle, 8 by holes on 10 x the { the Ways more this r of ; the 1 the built , ex- ater uto- into Fig- The as 6 ) de- |. In pro- ited. > the One al to vy 9, urns e for or 7 The ove- Ww of ob of t-up. POPULAR SCIENCE MONTHLY 93 Stop Mistakes in Painting — follow the Household Painting Guide TOPAINT— |TOVARNISH SURFACE NAMED BELOW | NAMED BELOW

S-W Auto Enamel AUTOMOBILES .. ae ito Enames

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For instance~ © painting woodwork © Sirst thing todo. ©

ENAMEL USE PRODUCT NAMED BELOW

TO STAIN— USE PRODUCT |

| CEILINGS, Interior Exterior CONCRETE

Seeathar ! m car-Not Varnish Floorlac nome -<ibcatcepaiiaac Veivet Finish No 1044 | S-W Handcraft Stain

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Porch FURNITURE, Indoo: P. HOUSE OR GARAGE |. Exterior LINOLEUM

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Old Dutch Enamel Enameloid Old Dutch Enamel

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WALLS, Interior «Plaster or Wallboard

WICKER

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WOODWORK SWP House Paint Scar-Not Varnish Interior .......-.++ t-Tor Loox on the “Guide” for the right thing to use for woodwork. Consult the ‘‘Guide” before selecting the finish for any surface. Something is wrong when a once beautiful room has to be done over again too soon. The chances are the wrong type of material was used. Every expert knows that each type of sur- face (indoors and out) calls for its own type of paint. Paints must be selected according to type. The same is true of varnishes, of stains and enamels. When you look at the Household Painting Guide you look at authoritative recommenda- tions. On a line with the surface to be finished you pick out the correct material as easily as you select a color from the color card. Save this copy of the ‘‘Guide’’ for use when needed. THE SHERWIN~WILLIAMS Co. 659 CANAL ROAD, CLEVELAND, O. good work Largest Paint and Varnish Makers in the World Getting Hire a good painterif you have big work good one, ’

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Your “Paint Headquarters” serves you with the Sherwin-Williams Household‘ Guide. It will pay you to look up this store. You will know “Paint Headquarters” by the Household Guide displayed in the window and inside the store. This store serves you intelli- gently, backed by the “‘Guide.”” The proprie- tor and clerks help you save money by avoid- ing mistakes. Look for this store and “follow the ‘Guide’.”’ It costs you nothing to be sure. Write for free suggestions on your painting problems to the S-W Dep’t of Home Decora- tion. Ask, also, for free booklet B450 and the handsome set of color plates giving eight beautiful color schemes for different rooms. Send 50c (65c in Canada) for the 177 page book of valuable detailed information on beautifying the home. Reproductions of the latest color ideas for interior and exterior—a book you would not part with for many times its price. Write Dept. B 435 at address below.

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BETTER SHOP METHODS DEPARTMENT OF POPULAR SCIENCE MONTHLY How to Avoid Forcing New Belts | over Their Pulleys MELLWRIGHTS agree that it is bad | i practice to force one of the edges of a large belt to catch on a pulley and then run on the belt either by hand or by power. This is apt to cause the belt to stretch more on one side than on the other and injure it permanently. Where conditions allow it, a good kink for putting large belts on the pulleys is to loosen the adjusting screws on the hang- ers, as shown. This allows the shaft to move over, temporarily shortening the | distance between the shaft centers, Sometimes the shaft may be moved in- ward 2 in. or more, thus making it pos- sible to put the belt on easily. Shortening the center distance 2 in. is equivalent to eis adding 4 in. to the : - belt’s length. To > assist further, one of the hanger bolts may be loosened to allow the hanger to swing inward. Where patented overhead beams are employed, it is sometimes possible mm iy : wn ‘i a S = 5 For Shop or School i Belt is slipped over Without touching loosened pulley the adjusting N your training at school or screws. 5 After the belt is on the pulleys, bring in the shop, Brown & Sharpe the hanger back to its normal position. tools will help you on the This is a simple thing to do by turning road to good work. the nuts where the first and second meth- ods mentioned above are employed. The A Brown & Sh arpe “Set of original position of the hanger should Seeaiinndl Tonte Wo BAT” Saas always be marked before moving, to avoid otan ar OOIS INO. equip tedious realining. Turn the bearing and you with the necessary tools to adjusting screws back to their original The No. 847 Set contains 8 useful : 4 ositions. These positions are easil tools. The case can be folded and is of meet the jobs of checking, meas- P . p ily a convenient size to slip in the pocket. ‘ee fae tapork whick found because the screw on the opposite Size folded 7% x 435" x 134". uring ar aying Out WOrK W 1c¢cn side and the top screw need not be moved arise daily. at all. 5 ‘ To be sure, this method is not always For getting measurements in practical where there are belts running in thousandths of an inch, . 7” both directions, as on a common line Rex Mic , : : shaft, but where it can be employed, it is ex .Viicrometer 1S an inex- well worth while—W. F. SCHAPHORST, pensive but dependable tool. Newark, N. J. It has proven its worth by giving — mechanics long years of faithful Simplified Lathe Tool Chucks sary HUCKS for holding a variety of lathe vice. 7 dc C tools can be made quickly and easily These tools will help you do along the lines shown in the accompary- : cc ing illustration. é the best work. Start right with A short length of cold rolled steel is cut a complete set of Brown & lengthwise with a Sharpe tools. CUTTER TAPER saw to form the : clamp jaw. The If you want a handy pocket ————=)\\ two parts then are reference book write today for SSE “Connected ri is) a Brown a Sharpe Small ,Tool o allt loosely with a bot. | 4 A setscrew at the | Catalog No. 29. q rear of the mov- The rectangular shape of the frame SSS SSS a able jaw provides sa Renal comruage Decimal ~ Qe = pressure for hold- quivalents of parts of an inch a ° ° a Brown & Sharpe Mfg. Co. Holder for toolbits ing any form of Y small cutting tool. | Providence, R. I., U.S.A. The end of the bar is turned to a taper to fit the headstock or tail spindle of the lathe. | . The same chuck also can be used in the “Standard of the Mechanical World ” | ari press in conjunction with a fly cutter | of the usual type.—G. L.’ — DOTTED CLIND UECTUONCG NEVADTVUENT OF POPIIT ARP CCIFNCE VONTHILY

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—! Belts | | is bad | iges of d then or by elt to mn the d kink 7S is to hang- 1aft to 1g the enters, red in- it pos- ‘tening lent to to the n. “To er, one rr bolts ened to hanger nward. itented beams 1d, it is ossible - entire orward yuching sting , bring osition. turning 1 meth- d. The should 0 avoid ing and original easily pposite moved always ning in on line ed, it is PHORST, ucks of lathe d easily mpany- el is cut with a rm. the yr, The then are quite h a bolt. y at the) ne mov- provides or hold- form of ing tool. » a taper le of the ed in the POPULAR SCIENCE MONTHLY ly cutter — $$$ A new Kodak with a new shutter Nos. 1A and 2C Kodaks Series III Both models are equipped with the famous Kodak Ana- stigmat lens 7.7 and the ac- curate Diomatic shutter. Mechanically precise; Optically proficient A fully-jeweled watch is corrected to one second but the Dio- matic shutter must time up to 1/100 of a second—and it does. Fractions of seconds—1/10, 1/25, 1/50, 1/100—are clipped with greatest accuracy and this mechanical precision, together with the sharp-cutting Kodak Anastigmat lens f7.7, makes good picture- making all the easier. Additional refinements—the new quick action focusing device, the rising front and the automatic shutter dial, which points out the proper exposure un- der existing light conditions—combine to equip an unusually capable camera, at a conservative price. PRICES No. 1A Kodak, Series III, pictures 24x41 inches - $30 No. 2C Kodak, Series III, pictures 23x4Z inches” - 33 If it isn’t an Eastman, it isn’t a Kodak Eastman Kodak Company, Rochester,N. Y ., ric Kodak city

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BETTER SHOP METHODS DEPARTMENT OF POPULAR SCIENCE MONTHLY | ; ; J ; ; A motor-driven home workshop \that you can build yourself If you have electricity you can easily build this motor-driven home workshop. Then you can construct all the things you have always wanted to, in wood or metal, at a great saving in time. Do all the work yourself, save money and have loads of fun besides. Starting with the bench, superstructure, and a one-quarter horse-power motor, you can build up this home workshop with the Goodell-Pratt tools listed at the right. Send for free illustrated folder Get all the details of this new popular home work- shop. Find out how reasonably it can bein- stalled. Free folder explains simply and clearly what to buy, the cost, and other details. A postcard will bring this folder at once. Other tools for the amateur mechanic In the Goodell-Pratt Catalog No. 15, you will find many tools, at low cost, that will help you do more and better work. Write for it. It’s free. GOODELL-PRATT COMPANY GREENFIELD,MASS. © Soolemitis, Makers of Mr. Punch What this home workshop consists of: (A) (B) (C) (D) (E) (F) (G) (A) Bench, Dimensions 58" x 26" x2" Legs 4" x4". Super - Structure. Two cast-iron flanges 7' in diameter, 1:;"' thick, bore 1" bolted to bench with four carriage bolts each 2?4"" long. Two pieces of XX heavy 1"' iron pipe 28" long threaded at both ends. Two pieces of 1" iron pipe 58"' long. Two 1" crosses. Two 1" close nipples; double heavy. Two 1" T’s, heavy duty type. Three 2ffsets sunporting jack forward, forged out by a blacksmith and off: set forward approximate: ly 12" and upward 10", Motor. One-quarter horsepower, 1,700-1,800 revolutions per minute (24) G. P. Polishing Head No. 24. (12) G. P. Bench Drill, No. 12. (125) G. P. Bench Lathe, No. 125. (132) No. 132 Slide Rest. (644) Milling Machine No. 644 (130) G. P. Countershafts No. 130. (728) G. P. Aluminum Pulley No. 728. (729) G. P. Aluminum Pulley No. 729. GOODELL PRATT 1500 GOOD TOOLS Machining Troubles (Continued from page 90) operator was roughing out the hole with a core drill as shown at A in Fig. 3. As he found that the tool “walked around,” fol- lowing the cored hole, he put a large bar of steel B in the side head of the machine and used it as a support for the drill, but it did very little good. I was passing through the shop at the time, so I in- quired, ‘‘ What’s the trouble, Archie?” “Well, sir, this cored hole doesn’t run true and I’m trying to use the side head to hold the drill from wabbling.” “Why don’t you bore the hole instead of using a core drill?” I asked. “‘Oh, that’s too slow,” he replied. “J ean’t get the work out fast enough that way.” So I told him to get a tool like that shown at C and set it so as to generate a true running hole, D, for a short distance in the hub of the casting, boring it about 1/64 in. smaller than the diameter of the eore drill. He soon caught the idea and found that after the core drill had once been started in a true running hole, it fol- lowed the same direction very well and was not so greatly influenced by the irreg- ularities of the cored hole as it had been previously. A single boring cut following the core drill and then a reaming opera- tion gave an accurate hole concentric with the outside surface. NY time you have a job to do that is troublesome, first make sure that you know the cause of the trouble—then remove the cause and your job is half done. “‘Chattering” is found in nearly all kinds of cutting, drilling, boring, turning, facing and milling operations, and sometimes it is difficult to find the cause of the trouble. It may be in the machine itself, in the work-holding device, or in the tools. If your machine spindle and various gibs are snug and tight, so that there is no chance for looseness here, you can eliminate the machine in looking for the trouble. If your method of holding gives ample sup- port to the work and there is no spring to it, you can forget this also and make up your mind that the trouble lies with the tools themselves or the method of holding the tools. Sometimes a very simple remedy can be applied, as in the case shown in Fig. 4. The work A was a steel ring forging about 7 in. in diameter that was to be faced at B and a recess cut at C. There were other operations on the work, but with these we are not interested. 7 E piece was held in chuck jaws anda shovel nose tool D, having a 1-1. face and 1% in. deep, was used for the recess. The tool was ground as shown at E and set \% in. above center to give a slight shearing action to the cut. I had to feed the tool into the stock in the direction of the arrow F. Unfortunately, the machine, a hor- zontal turret lathe, happened to be placed on the floor directly over the superintend- ent’s office. As I started the job, hand feeding the tool into the work, it began to “chatter” very badly. I pulled it out and (Continued on page 98)

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POPULAR SCIENCE MONTHLY 97 7 ——————— n.| & ‘Wherever men depend upon Cutting tools most’ | As he - fol- : ze bar achine ll, but assing i 2 ine e?” ’t run 2 head ¥ * nstead d. “7 h that e that prate a istance about of the ea and d once , it fol- ll and 2 irreg- d been lowing opera- centric that is e that —then is half 1] kinds , facing imes it rouble. in the ols. If You should use Simonds files be- ribs are cause of their teeth—their sharp- chance ate the ole. If yle sup- ring to ake up rith the holding ness and their hardness. If you would have good cutting tools worthy ol the task you assign to them, say SI-MONDS to your dealer. The Simonds organization hasbeen produc- ing cutting edges of tempered steel since 7 can be Fig. 4. forging s to be There rk, but 1832. You may be certain that a tool bearing the Simonds name is RIGHT — in materials — in design — in work- manship. But be sure to pronotince the name SI-MONDS. vs and a a 1-in. for the t . gem SIMONDS SAW AND STEEL COMPANY I had to IS) “ The Saw Makers” Fitchburg, Mass. Established 1832 lirection Branch Offices in Principal Cities a hori- e placed rintend- yb, hand began to out and —$—$———

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we te oe a CE Slat OUP A Mee ee RE ga it cae te we Oe EE es sr b> ip UMBIA’ HOT SHOT ES) BATTERY = a Fees ff gh teal mata y ¢ | wveote HOT | B Columbia Hot Shot Batteries contain 4, 5 or 6 cellsin a neat water-proof steel case. Packaged Electrical Power FOR long-lasting punch and pep on home, office, work- shop and laboratory electrical tasks, use Columbia Eveready Dry Batteries. Press the button or throw the switch and they respond with lightning speed. Open the circuit and the Columbia Eveready rests easy, recuperating its force and restoring its energy. Bells, buzzers, telephones and telegraphs come to vivid life at the command of Columbia Eveready Dry Batteries. Lights for dark places burn brilliantly. Gas engines putt-putt away without a miss when Columbia Eveready Dry Batteries furnish crackling hot sparks for ignition. Electrical experiments and tests are made easily when you have these good bat- teries on hand. Industrial and college laboratories use them when steady, unvarying voltage and amperage are needed for delicate work. When you buy dry batteries, don’t just ask for “a dry cell.” Ask for “Columbia Eveready Dry Batteries” by name and get 100% battery efficiency. Columbia Eveready Dry Batteries are sold by electrical, hard- ware and auto accessory shops, implement dealers, marine supply dealers, garages and general stores. Columbia Eveready Ignitors can be purchased equipped with Fahnestock Spring Clip Binding Posts at no extra cost to you. Manufactured and guaranteed by NATIONAL CARBON Co., INC., New York—San Francisco Canadian National Carbon Co., Limited, Toronto, Ontario Columbia Dry Batteries -they last longer for— Gas engine ignition Telephone and telegraph Doorbells Buzzers Motor boat ignition Ringing burglar Firing blasts Heat regulators alarms Lighting tents an: Tractor ignition Electric clocks outbuildings Starting Fords Calling Running toys Protecting bank vaults porters io “A BETTER SHOP METHODS DEPARTMENT OF POPULAR SCIENCE MONTHLY Machining Troubles (Continued from page 96) tried again with about the same result except that the superintendent came rush. ing up the stairs and wanted to know what I was trying to do.. Said I shook the whitewash off the ceiling all over his desk and made a few other remarks unneces- sary to repeat. I didn’t want to lose my job and, of course, I saw that the “chatter” was caused by the tool springing and digging into the work. I pushed it back as far as I could into the holder, so as to have as small an overhang as possible, but still it chattered. Finally I took the tool out and WORK with a pocket carborundum stone dressed it up on the end to form a nar- WORK row “‘land,” as tt =z shown at G, just | ° E below the cut- ll ting edge. This land gave _ enough support to the cutting ea edge to prevent Fig. 7. Good and bac the tool from methods in turning digging in. The chatter stopped at once and the tool thus dressed produced a good smooth surface. Too much overhang of tools is a fre- quent cause of chatter. In lathe work, long tools often are used as shown at A in Fig. 5. If the overhang is too great, the tool may deflect on account of the pres- sure of the cut, and by springing back | into the work cause chatter. Under a| heavy cut, even when the overhang is | reduced to a minimum, there may be chatter, but sometimes this can be remedied by adding an extra toolpost, as shown at B, to give additional rigidity. By setting the tool a trifle below center, as at C, any spring to the tool causes it to deflect away from the work, as shown by the dotted line, and, therefore, it does not tend to dig in. A “‘goose-neck”’ tool, as shown at D, also is very useful for wide cuts or for forming cuts, and this type of holder prevents chatter by allowing the tool to spring away from. the work without dig- ging in. I once had a number of long slender shafts to rough turn, as shown at A in Fig. 6, and, following the usual practice, I turned a spot on the shaft and applied a steady-rest at B. When I started feeding the tool in the direction of the arrow, 4 chatter became apparent at approximate- ly the point C. This chatter increased for a short distance and then gradually diminished as the tool approached the steady-rest. This was doubtless due toa slight amount of vibration between the steady-rest B and the headstock. Fig. 8. Facing and bottoming operations (Continued on page 100) = A 1 Ny i, . a\ Va a e si

Page 99

result, € rush- know 0k the is desk neces. ave as still it ut and pocket ndum ssed it he end a nar- Ye lig as G, just ie cut- . This gave upport -utting revent from n. The topped »duced a fre- work, it A in at, the 2 pres- r back nder a ang is ay be an be ost, as gidity. ter, as s it to wn by es not at D,

MILL FOR | US CUT and tions lied a eding ‘OW, @ mate-

Welcome News for Gasoline Alley HIS will sound mighty good to you if you’ve been : along in Gasoline Alley with a flock of assorted style and misfit wrenches. You can now havea kit of Snap-On Socket Wrenches, the tools mechanics use and recommend, that will service your car in garage style. No matter what car you drive your Snap-Ons will be especially selected for your use. Any one of the 200,000 mechanic users of Snap-On Wrenches would pick out of his Master Service Set the same identical tools that are in your kit for work on your particular make of car. The interchangeable principle of Snap-Ons gives you in a handful of units, wrench combinations with which you can service your car throughout as easily as you can take off rim nuts with a rim wrench. Decide now to own this real set of tools. Keep your car tightened up—prevent wear and tear and replacements of worn parts—be prepared for road emergencies! You'll be surprised how little a kit of Snap-On will cost you. nap-on INTERCHANGEABLE Socket Wrenches MOTOR TOOL SPECIALTY CO. Distributors 14 E. JACKSON BLVD., CHICAGO, ILL.

POPULAR SCIENCE MONTHLY

R dyhi' | WH yt <=. NG Saas PAM e” / ema : = / L ah | ae

The dealer who has this Snap-On Cabinet is a socket wrench expert. He can tell you anything you want to know about ’em—supply you with the right wrenches for your car or for any other purpose. Fill out and mail the coupon today. Snap-On Interchangeable Socket Wrenches have been approved by an impartial author- ity—Popular Science Institute of Standards. e MOTOR TOOL SPECIALTY CO., i 14 E. Jackson Blvd., CHICAGO. Send me Free illustrated folder and full particulars about Snap-on Kit ae ......car. (If interested in Master Mechanic’s Kit, for servicing all cars, check here. . ) I buy tools from Name.... Address....

Page 100

cow ne ame nt rr lites Taal ee eee 2! la NSS Py oo a Se ee ee i. SL hs ae aaa Sn TREE ie Cae eee cl Pen ne BEE rs ge > BETTER SHOP METHODS DEPARTMENT OF POPULAR SCIENCE MONTHLY Anyone can use a storage battery now CCHARGING a storage battery ten years ago was a task needing expensive apparatus and the services of a specialist. Today, anyone can do it in the home. No knowledge of electricity is needed. It can be done economically, simply, automatically with The New Silent LD SEAL HOMCHARGER just as more than 200,000 satisfied users of Homchargers are doing right now. If you are one of the many who envy the results of storage battery tubes but think you can’t enjoy them unless you are a battery expert, go right out now and buy those tubes, a battery and a Gold Seal Homcharger. ; Here’s all you have to do to maintain a storage battery: add a little water once in a while (your eye will tell you when); charge it regularly. To use the Homcharger, screw a plug in any lamp socket, slip two spring clips over the battery ter- minals, go to bed and forget about it. Next morning the battery is charged. What could be easier? The Gold Seal Homcharger: simple, efficient, dependable, quick. Cannot injure battery, furnishings, anything or any- body. Handsome, finished in mahogany-red and gold. Ap- proved by Fire Insurance Underwriters. Unqualifiedly guar- anteed. Only one moving part, replaceable for $1 after thou- sands of hours of use. Silent: its faint hum cannot be heard in next room. Popularly Priced: buy it at your dealer’s for $18.50 com- plete; $25.00 in Canada. For radio at its best, use storage battery tubes, any good battery and the Gold Seal Homcharger. FREE! Send for our interesting free booklet, ‘“The Secret of Distance and Volume in Radio,’”’ con- taining valuable information on this subject and fully describing the GOLD SEAL HOMCHARGER. THE AUTOMATIC ELECTRICAL DEVICES CO. 131 WEST THIRD STREET, CINCINNATI, OHIO. Largest Manufacturers of Vibrating Rectifiers in the World. Machining Troubles (Continued from page 98) I removed the steady-rest and set upa | follow rest, as shown at D, and stil] found | more or less chatter, which was most pro. nounced near the tailstock and gradually | diminished as the tool approached the headstock, finally ceasing altogether about as indicated in the diagram. This had me puzzled for a while, for the marks on the shaft took the form of a long, gradually | diminishing group of spiral lines of eon. stantly changing pitch, but finally I made | up my mind that the peculiarity was caused by torsion in the work. The farther away the tool was from the point | | where the shaft was driven, the more | | flexibility there was in the shaft, so that | _ the resistance of the work to the tool and | | the twisting of the shaft caused the | trouble. The only remedy was a finer | feed combined with higher speed. I have | recently seen a much more pronounced case caused by reducing with a special | three-tool hollow mill a 2-in. shaft to 1 in, | diameter in a single operation with a very | coarse feed. ANY men like to use a round-nose | toolfor roughingstock, butsuch tools often chatter because of so much surface | in contact with the work. I saw a man in | the factory the other day roughing downa bar of stock with a round-nose tool set in the toolpost as shown at A in Fig. 7 (page 98). Of course, the arc of contact with the work was a quarter circle, as in- dicated at B. The tool was being fed in the direction C and, therefore, the natural pressure tended to throw the tool into the work. The way in which the tool was set and the action produced on it reminded me of a man walking along the sidewalk pushing a cane before him. It is evident from the diagram that this is a very bad way to set up a tool. If you must use a round-nose tool for this kind of work, set it up as shown at D, so that the pressure of the cut will throw it away from the work and not into it. Some men use a side tool, as shown at E, for roughing down a piece of stock. They give it a slight round on the point F so that it will not leave a surface too much like a thread and also so that it will stand | up better. This will answer very well for large stock reductions by using a very fine feed and comparatively slow speed. A better way, however, is shown in the | diagram at G, as a heavier feed can be used with this type of tool. It is best to set the tool on center or slightly below it; it should never be set above center. © In facing a steel forging or casting, 4 wide tool often can be used to advanatge with a comparatively coarse feed, as In- dicated in Fig. 8, if you set the tool from 14 to \ in. below center, as indicated at A. This gives a better cutting action because the metal is removed by a shearing cut. Any tools used for facing cuts will remove metal faster and produce a smoother sur- face if a shearing cut can be used. A face | mill, for example, having teeth 1 m. ahead of center will do better work than one with teeth cut on center. I remember a facing job on malleable iron where I had occasion to use 4 face and bottoming mill on a turret lathe, as (Continued on page 102)

Page 101

Set upa | ill found | nounced special | to Lin. | ha very | surface 2 man in | r downa contact was set eminded sidewalk evident very bad tool for wn at D, r a very speed. n in the | below it; Tr. lathe, as POPULAR SCIENCE. MONTHLY $15.0 oe Home INTERNATIONAL PRIZES First PrizE— $15,000 Model Electrical Home _ (To be built on lot provided by winner) Two SEcoNnD Prizrs—1 Boy—1 Girl $1200 scholarship in American or Canadian Col- ; Jege or University of accepted standard. Two TuirD Prizes—1 Boy—1 Girl $600 scholarship in American or Canadian Col- lege or University of accepted standard. Two FourtH Prizes—1 Boy—1 Girl $600 scholarship in American or Canadian Col- ‘ lege or University of accepted standard. Two FirrH Prizes—1 Boy—1 Girl $300 scholarship in American or Canadian Col- ¥ lege or University of accepted standard. Two SixtTH Prizes—1 Boy—1 Girl $300 scholarship in American or Canadian Col- } lege or University of accepted standard. “REMEMBER: To compete successfully in the Home Lighting Contest, your child must obtain a copy of this Home Lighting Primer’ from your localelectrical people. Have your child go to the local electrical club or league, or to the office where you pay your electric light bills and get free, the ‘Home Lighting Primer.” —Jt tells how to win this $15,000 electrical home or a college scholarship, contains a complete _ illustrated series of simple lessons on better home lighting and fully explains both the local and the international phases of the Home Lighting Contest activity. Watch for the announcement of the essay contest in your town. — Any school child, ten years of age or older, may compete. Better Light—Better Sight The Home Lighting Contest is designed to teach the public, particularly the young generation, more about electric light, and how in their daily lives to properly use it so that in future years there shall be less eye trouble and better general health. This activity has the support of our leading educational and health authorities. Your Local Electric People Will Help The Electrical League or Club, or the Electric Light Company serving you, will gladly enter your children in the Home Light- ing Contest, supply them with the “Home Lighting Primer” and tell them what to do. There will be local prizes, and the winning children will be contestants for the international prizes—the $15,000 electrical home and the university scholarships. Be sure that your children enroll for the essay contest as soon as it is announced in your city cr town. Watch your home paper. “The gua LIGHTING EDUCATIONAL 680 Fifth Avenue - ~°- ° New York,NY I I On i in IO OO Oe rr Ne NN ee ee

Page 102

tthe, vam Sci ll sl eae aaa Ta eh tt A es i ie Aa a Aa ! ' | 4 BETTER SHOP METHODS DEPARTMENT OF POPULAR SCIENCE MONTHLY *: a aL FO gaa” a = ¢ “—o en. ga ra i. Te Lf 4-. aig, . on Pom —~, General Motors Tracks The Guarantee of Better Haulage Ownership of a GMC truck is a guarantee of uninterrupted, economical haulage. Not alone because GMC trucks are built of the finest materials— Notalone because they embody exclusive features of design that make them operate cheaper, wear longer and that allow every wearing pert to be renewed indefinitely— Not alone because their list price is lower and represents the actual cost of building plus a fair profit only — Not because of any of these individually, but because together, they provide every quality essential to profitable trucking. GENERAL MOTORS TRUCK COMPANY Division of General Motors Corporation PONTIAC, MICHIGAN JQ RECENTLY we had a large number of General Motors Truck Co. Pontiac, Michigan Department 47 Gentlemen: Please send me further information. I am interested in a (truck) (dealership). Le, Stripped Drafting Instrument Nut Replaced with Babbitt About four years ago, when the nut | on my bow dividers wore out, q| friend suggested that I pour a new nut | out of hard babbitt. We made a smal] wooden mold as shown and poured the | BABBITT NUT—~ & WOODEN MOLD YZaygrZZ babbitt around the screw. A little coaxing | loosened the babbitt from the screw, and the nut so made has been in use ever since.—F. N. C. Driving Nuts Rapidly bolts on which the nuts had to be driven close up under the heads. As the cost of screwing them up by hand was prohibitive, a driving tool was made as shown. With this we com- pleted the work in a short time. The tool is a bushing, which first was drilled out to clear the bolt. The outer or eam SS end of the bush- : ing then was ———— = bored to a 90- degree taper. Six slots were cut, as indicated, and the bush- ing was held in the chuck of a lathe. In use, the nut was started on the bolt by hand, and then held against the slotted part of the bushing, which causes it to turn with the chuck. When square nuts are used, it is necessary to use a bushing with only four slots.—R. H. KASPER. Machining Troubles (Continued from page 100) indicated at B. The mill was about 3 in. in diameter and had 12 teeth cut on center with a 3-in. radius at the end. The hole previously had been bored and rough faced and there was no trouble about these operations, but when it came to the final facing and cutting of the radius, I found it almost impossible to make the mill take hold, even with all the pressure I could apply to the turret-feed hand wheel. All I could get was a scraping action, producing the chip in a fine pow- der, and an occasional chatter. I put my wits to work and decided that the mill would not cut because each tooth had nearly 1 in. of surface in contact with the work, 12 in. for all the teeth, equivalent to a cut nearly as wide as this and requiring more pressure than I pos- sibly could apply to the hand wheel. | took out the mill and ground away the cutting edges on every alternate tooth, leaving only 6 cutting teeth. After doing this I had no further difficulty, as the mill cut freely and gave a smooth finished sur- face. I have had a similar experience since that time with other tools and the experi | ence gained on this one job has helped me materially on others. —

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POPULAR SCIENCE MONTHLY 103 | =| | Clever mechanical contrivance | “| makes cold radiators HOT — J Ai xnviyptected and improved air valve, known aa Ai, —— has been produced after many years of experimenting in the In- — stitute of Thermal Research at Buffalo, N.Y. This valve not only prin rids steam radiators of cold air under all conditions of operation, in use but automatically prevents the escape of the steam itself. The result is hot radiators. Installed by anyone in 2 minutes mber of ° e to be —and works without adjustment S the — No tools are needed to install Arrin. It is made to fit the same hole With provided for old-fashioned air valves, and is tightly screwed on ‘ sii in a few seconds. wor . time. After that, it need never be touched. There ) i ° ° ° : : SLSR EB AE CR La OE eS js “77 is nothing to adjust and no one can tamper with by oe le drilled it. Air1iD works automatically and permanently , _o to keep the radiator hot. » tae. 4 The moment that steam fills the ra- 1 Was Why many radiators diator and enters Arrmw's innercham- 2 90- half ] d ber, a remarkable contrivance shuts per. Six are co the door of escape, and holds back e bush- min : d the steam. This operation is con- e. Co & up from the boiler, sewapian pushes a trolled by a sensitive little float he bolt air ahead of it. Unless the air can get out, it which expands under the heat of ist. the fills the farther end of the radiator, and acts as steam, and forces a pin up into the aaa a wall to keep back’ the vent-hole—making the valve absolutely it is steam. Hence many ‘“85t ly four good radiators are con- Water, always present in steam pipes, will : very often get into the chamber of the air tinually half cold. valve. This menace has been foreseen and . provided for: the float rises on the water and If youexamineAiriwclose- immediately shuts the vent. A glance at the 8 in. in ly, you will notice a tiny hole illustration of Airm will show you the in- . center at the very top of its nickel- genious syphon-pipe which draws the water he hole plated cone. Out of this hole back into the radiator. Because the valve Tough the air can pass freely, until the radiator is full of hot chamber is free from water, the path of es- : - = steam. But this is only half the story. cape is always open for cold air. idius, I . ake the SEND COUPON with $1.60 and watch AIRID: work 1 hand Air is guaranteed by the American Radiator and your first Arrm will come to you by return pi Company. The only way to appreciate how differ- mail. Your heating contractor can sell you more ent it is from all other air valves is to see it work. Arrips at the same price, after this one has ed that Try it on your coldest radiator; transform your demonstrated its magic power to make a cold h — chilliest room, Fill in the coupon, attach $1.60, - radiator hot. oo. contac it | > teeth, Pa ss this Made and guaranteed by the uy” sual So age AMERICAN RADIATOR COMPANY _-7~ COMPANY yay the Sold at all heating and plumbing shops Pil 1807 Elmwood Ave. | : tooth, Pd Buffalo, N.Y. | r doing a“ I am enclosing $1.60 for an AIRID the mill ag Air Valve to make my coldest radi- j ed sur- ator hot. | ce since Name... j xpe> Address ......---- | ped me j $$

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fear ti Ey | babes me ‘To-morrow’s Telephones So vital a factor has the telephone become in American life that the demand for it would undoubtedly grow even without increases in population. New businesses are founded; others expand. New homes are established in town and city, in suburban dwellings and apartment houses. To meet the needs of America, to-day and to-morrow, with the best and cheapest telephone service, is the responsibility of the Bell System. The telephone will grow with the population and prosperity of the country, and the plans of to-day must anticipate the growth of to-morrow. The service which is given to-day was anticipated and provision was made for it, long in advance. Money was provided, new developments were undertaken, construction work was carried through on a large scale. The Bell System, that is, the American Telephone and Telegraph Company and Associated Companies, has continuously met these requirements. It has enlisted the genius of technical development and the savings of investors for investment in plant construction. Over 315,000 men and women are owners of the American Company’s stock and over half a million are investors in the securities of the System. With a sound financial structure, a management which is reflected in a high quality of telephone service, the Bell System is enabled to serve the increasing requirements of the American public. AMERICAN TELEPHONE AND TELEGRAPH COMPANY AND ASSOCIATED COMPANIES BELL SYSTEM One Policy, One System, Universal Service The New Tinsmith Helper “= ae and Pattern Book By Hall V. Williams The Conn Saxophone, easiest of all wind instru: because of i = _A handbook giving a practical explanation of nomen somata + a eal simple geometrical problems, the forming of seams, ure and profit to you. Write for details of laps and joints, and one hundred problems on the Free Trial; Easy Payment plan on any Conn layout and cutting of conical vessels, elbows and instrument. Used by world-famous artists; piping, furnace fittings, ducts, gutters, leaders and Conns cost no more than others. ; roofing, unclad fireproof doors, cornice and sky- recipes, etc. Ve “yh ONN 4928 pp. 248 Illus. $3.00 J ~ BA 7 BAND Popular Science Monthly C.G.c Ltd., 1032 Bidg., Elkt ~~ light work with 165 tables and many shop kinks, BETTER SHOP METHODS DEPARTMENT OF POPULAR SCIENCE MONTHLY How to Solve Milling Problems with a Dividing Head (Continued from page 92) When the index head is connected by suit. able gearing to the feed screw of the table the movement of both will be positive and a cutter in contact with the work will cut a spiral or helix around the circumference of the cylinder. The gearing to do this class of work is found in tabulations provided with the machine. The table is swiveled to the angle given for the helix angle clearance right or left, depending upon the spiral being cut. Each successive cut must be indexed by hand as for plain indexing; this is governed by the number of divi- sions or teeth to be cut. When a spiral is being cut, the index plate rotates with the work. It should be held stationary when indexing the teeth and the cutter brought back to the start- ing point before turning for the next cut, To do this, drop the back lock pin into place while turning the crank and release it before starting the cut. ‘7T principle of milling spirals is based upon the relation of the lead or pitch of the spiral to be cut with the lead or pitch of the feed screw of the table and it always signifies the distance the table will advance in one revolution of the index head spindle. Leads from about 34 in. up to 60 in. can be cut with the average index head. For special leads it is some- times necessary to provide special gearing or use compound gearing. Spiral milling is confined mostly to the grooving of cut- ters, reamers, twist drills, taps, spiral gears, and similar work. Figure 5 shows a cam milling job. In this work the head is geared the same as for spiral milling when the cam has a uni- form or constant rise, and the lead can be varied by changing the angle of inclina- tion of the head. The cam is always turned back to the starting point for each new cut in order to keep the back lash in one direction all the time. When possible, set the cutter to mill on the under side of the cam. Tabulations usually are fur- nished for finding the correct gears and angles for various cam rises or leads. Differential indexing is used to extend the range of divisions beyond the limits of the available index circles on the plates. It is about the same in principle as com- pound indexing, but it cannot be used for spiral milling work. More than 2000 divisions are possible with this system, whereas 380 is about the limit when using the index plates. Differential indexing is accomplished through a combination of gearing whereby the spindle of the index head is geared to a worm wheel shaft and connected with suitable idler gears. This system can only be used with the head in a horizontal position, as it requires a gear on the spindle. Some milling machine index tables are very complete and contain all the neces- sary information in regard to placing the gears in the right place, and generally illustrate one or two examples of typical problems. When there is no gear indi- cated in any of the columns of the table, the indexing is plain. Where gears are (Continued on page 106) en SORES WARCRY MANUPACTUNRD 250 Fourth Ave. New York City

Page 105

tie Oblems id d by suit. the table, ‘itive and neces- ing the nerally typical ar indi- e table, ars are

————————— POPULAR SCIENCE MONTHLY

Pe Pull a Good One When You Write—or Lend cA Pen You Need Not Apologize For Never Failing —‘Never Ailing A Point the Other Man’s Hand Cannot Distort—Jewel-Smooth—Guaranteed 25 Years ULL a good one — meet the world on even terms. For today Parker Duofold is the pen with which Success associates— it’s replacing old pens, thousands per day. For solely to have this super-writer is worth several times its price, aside from the high intrinsic value of the Duofold itself. Its balanced symmetry and jewel-smooth point steady the hand, abolish resistance and give one that stimulating urge to write. Not only this, they bring to the hand that speed and character which win with the world. And wherever you carry this black-tipped lacquer-red beauty it evokes admiration and respect. A color that makes it a hard pen to lose— an Over-size barrel which holds that extra ink that is just like money in the bank when you need it. “I signed 1067 checks with one filling of my Duofold in just 1 hr. 30 min.,” writes an executive of the Public Securities Corporation, Los Angeles. Yet Parker Duofold not only carries ink to spare, this Over-size barrel forms a man-size grip that can’t cramp your style or your fingers as does a pen too small. A sure-fire writer on account of the “Lucky Curve” feed. A clean pen to carry and handle on account of the double sleeve of the Duo-Sleeve Cap. Fill it by simply pressing a Button, capped inside the barrel where it can’t disfigure the beauty or catch on the clothing. And fill less often than the usual pen. Any good pen counter will sell you this Parker classic on 30 days’ approval —black-tipped lacquer-red or flashing plain black. Step in and get it. And come out and pull a good one. THE PARKER PEN COMPANY - JANESVILLE, WISCONSIN NEW YORK CHICAGO SAN FRANCISCO SPOKANE THE PARKER FOUNTAIN PEN COMPANY, LIMITED, TORONTO, CANADA Parker Duofold Pencils to match the pen, $3.50 d Black

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‘old Duette—$8.50

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¥ ie A bigger hold! Compare it with the hold on old-type shaving sticks ILLIAMS Doublecap is the newest thing in shaving sticks. It does away with slippery, finger-tip holds. Gives you a handle you can wrap your fingers around. And from first to last, even when the soap is but a thin wafer, the Doublecap hold remains the same. Your first Doublecap at 35c is a perma- nentinvestment. Whenthe original soap is gone, get a Doublecap Re-load, 25c. A Doublecap stick is astoundingly economical. “It never uses up,” says one man. And it’s a time-saver. Apply it to your cheeks. Then take your brush. Instantly you have billows of thick, creamy lather. And such lather! Only Williams can give it. It softens any beard quickly. Itslubric quality makes your skin pliable, instead of hard and resisting to the blade, and leaves your face feeling as smooth as a kid glove. Complete Doublecap is 35c; Double- cap Re-load, 25c. THE J.B. WILLIAMSCO., Glastonbury, Conn. The J. B. Williams Co. (Canada) Ltd. St. Patrick Street, Montreal

Aqua Velva is ournewest triumph—a scien- tific after-shaving formula. For free trial bottle, write Dept. 1010.

Doublecap Shaving Stick By the makers of the famous Williams Holder Top Stick, and Williams Shaving Cream with the Hinge-Cap BETTER SHOP METHODS DEPARTMENT OF POPULAR SCIENCE MONTHLY

Two Boring Tools that Aid in

Le CUTTER HEAD HIGH SPEED fe STEEL CUTTER LSS Te ea HOLLOW BAR) FOE )\ G9 7 f oe é ers FIG.2 CUTTING EDGE 14" ABOVE CENTER caine, Williams

Heavy Work oe boring large cored holes with a horizontal boring machine, the tool shown in Fig. 1 is well adapted. It is provided with two high speed toolbits, held in place by setscrews. This holder may be drilled to receive four tools, if de- sired, as in many cases two extra tools will do better and faster work. The holder should be a sliding fit on the bar and fastened with a setscrew. Place a piece of round brass under the setscrew so that the bar will not be marked. If the tool is to be set to a certain size for dupli- cating the same hole in many castings, the 1 ” 72 ROUND HIGH SPEED STEEL BORING BAR

ee er

FiG.} OILTUBE OIL HOLE

Tool for boring large cored holes and a “hog-nose’”’ drill for deep holes cutters may be set and ground to the re- quired size in the grinder. Figure 2 shows a design for a deep hole drill, or “‘hog-nose”’ drill, as it is some- times called. The body, including the shank, is made of cast iron for holes of large diameter. steel may be used. For holes up to 3 in. A pocket is milled in the front left-hand corner to receive a high speed steel cutter, which is fastened to the body with two cap bolts. body to supply oil to the cutter when working in steel. An oil tube is fitted to the For unusually long holes a hollow bar is used and the oil is pumped through the bar. Where a solid bar is used, a groove is cut on the outside of the bar to receive a 14-in. brass or copper oil tube. The body diameter of this type of drill should be about .010 in. smaller than the diameter of the hole. ground for size in place and on centers, and is relieved for side clearance. The cutter is

Solving Milling Problems (Continued from page 104) shown, the indexing is differential or com- pound; for this, all that is necessary is to find the gears having the number of teeth indicated and place them in their proper place as shown, select the correct index circle, and index with the crank as in plain indexing. The use of the universal index head covers a great variety of work and is capable of solving many intricate prob- lems in tool and jig making. It is one of the most interesting and absorbing devices found in the shop and is worthy of the best attention and study of enterprising young mechanics. And when once its fundamental principles are understood, it will be no longer just a box of mysteries. Wee id Batte ry

ASTRA

A24-Volt “B’’ Storage Batteryposi FREE with each purchase of a WOR, ge Pattery. The WORLD Battery is f,. teed quality and service. Back of Successful Manuf: Thousand ed Badsasa Users. You save tate _ Kia of Prices That Save and Satisfy Auto Batteries €-Vokt, 11 Plate $12.28 — Batteries G-Von, 13 Plate 14.25 > 200 Amps. 12350 22-Vot, 7 Plate 17.00 SVon: tac Ames: 14:50 tE C. O. D. eubj i 5 Spor cent tscou: Shes with o no pga 2-Yr. Guarantee Bond In Writing wan Each World Storage Battery Droves factory World performance. Mall faiveds endive you your cholve of PBS day orderinre seh alc — ae FREE. Write Tobay 2219 So. Wabash Ave. Dept. 7 ~~ Thie FREE ‘*B’’ Storage Battery the place of “B’’ be Gan bs Sd and ean ecg ok gy coll To ts d'vetall for $6.00. It Es the only bate ns ks, ‘er NO

e agains oi Ey handsome nickel finish Me tnsreey tt 20nd FREE 0 Geng. Bo cure to ennai wat to wan of the “B”" Bat- GIVEN F REE intr this geo |

Home Protection with an eens encasement,

Automatic will cost little Nearly every man ‘wants a gun in the house—he feels better able to protect his family. We are able to offer these Genuine Astra guns at special prices because we bought be- fore recent tariff raises became effective, Really fine guns, beautiful y finished, hard hitting. ( se standard ammu nition. Order direct from U. S. imperters, » Zshot ASTRA, C.0.Q. Automatic 8.95 25 CaL, 7 shot ASTRA, Automatic 9.95 25 caL, 7 shot ASTRA,, triple safety. 10.95 32 cal., 10 shot ASTRA, extra magazine, $16.95 “The Plainsman” Revolver

< ew: $2-20 and 38 long call- bre; except for difference in calibre, the same gun fin weight, size and appear- ance. A regular he-gun, best blued steel, fully guaranteed, uses standard revolver ammunition. $16.95. Write for firearms catalogue. We guaf- antee perfect workmanship and material; every gun brand new; of drop forged steel throughout. Before buying any gun insist on this guarantee. mo money unless you wish. Pay postman on delivery plus postage. Money cheerfully refunded if not fully satisfied, ACT NOW to get these SPECIAL LOW PRICES. WRITE TODAY. CALIFORNIA TRADING COMPANY Dept. 110 747 Warehouse St., Los Angeles, Cal.

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lly fine guns, dard amimu- Automatic, tic fety. azine, volver aed | Tong call- r difference e same gun nd appear- e-gun, best guaranteed, tion, Only We guar- 1 material; throughout. utes. on delivery * not fully 1AL LOW PANY geles, Cal. OED POPULAR SCIENCE MONTHLY THIS BATTERY WILL MATERIALLY REDUCE YOUR OPERATING COSTS ON HEAVY CURRENT SETS he AS 48 45 Ni Wi aN NEW! Eveready Heavy Duty “B” Battery. 45 volts, Three Fahnestock Clips. Length, 83% inches; width, 4% inches; height, '7°4 inches; weight, 13% pounds, New low price, $4.75 New Heavy Duty 45-volt “B” Extra Large Cells— | Extra Long Service For maximum “B” Battery economy, use this New Eveready Heavy Duty 45-volt “B” Battery, in the following general cases: 1—On all receiving sets operating at 90 volts or more, having four tubes without a “C” Battery, and all sets having five or more tubes, with or without a “C”’ Battery. 2—On all power amplifiers. 3—On all sets that pull heavy currents from the “B” Battery. Under the above conditions, the New Eveready Heavy Duty 45-volt “B” Battery will give much longer service than the 45-volt “B” Battery of usual size. If your receiving equipment falls under any of the above classifications, you can make a big saving in “B” Battery costs by using this New Eveready Heavy Duty 45-volt “B” Battery No. 770. No, 7112 Eveready Radio wae Dry Cell Specially manufactured for use with dry cell tubes No. 766 Eveready “B” 2234 volts. Six Battery No. 770 Eveready 6-volt Storage “_ Battery Manufactured and guaranteed by "ao teaee ef Tia NATIONAL CARBON COMPANY, Inc. Boro - Headquarters for Radio Battery Information New York—San Francisco Canadian National Carbon Co., Limited, Toronto, Ontario If you have any battery problem, write to Mr. G. C. Furness, Manager, Radio Division, National Carbon Co., Inc., 116 Thompson Ave., Long Island City, New York. No. 771 Eveready “C™ Battery Clarifes tone and prolongs “B” Battery life Z f Ph « Radio Batteries | ~ they last longer

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Receptrad Parts are engineered to Super- Heterodyne standards under the personal su- pervision of Lieut. Vic- tor Greiff. Their effi- ciency and _ perfect construction combine to produce a Super-Het. that is unsurpassed. Ask your dealer or write for free blueprint No. 6 of the Famous Pro uc? Greift 8-Tube Super—mentioning your dealer’s name and address ——— eS rs —— > oe Oscillo Coupler—mazxi- Other RECEPTRAD parts for the Super-" Tuned Filter Coupler— mum inductance in Heterodyne are two low loss coils, sim- minimum space. Two 3 RF-1716 Transformers—-Range 5 to 25 M. meters ilarly tuned to corre- : 1 Audio Traneformer, Type oe coils, one takes energy 1 Audio Transformer, Type ATX spond with intermediate through loop, while the 2 IMF By-Pass Condensers, Type G-1000 frequency transformer's other feeds its energy ¥ =. Price for all parts $53.50 best range. No inter- to first detector. Price, Lieut. Greiff’s famous Super-Heterodyne Manual, $1.50 ference—Real selectiv- Write for complete literature and : Pri 7 $6.00. prices on individual items ity. “Price, $7-50. RADIO RECEPTOR(CO. © 59 BANK STREET NEW YORK CITY Reason No. for Specifying SINGLE~HOLE MOUNTING SUPERIOR CONDENSERS Just ONE Hole to Bore HE only condenser that requires the drilling of just ONE hole. You can’t spoil the panel. No possibility of mounting screws pulling plates out of BORING ONE HOLE alignment. All types of Rathbun condenscrs T (except the No. 3 plate Vernier) are interchangeable in the same hole. Alterations in the circuit are thus mad INSERTING SHAFT extremely easy. ‘The Rathbun condensers incorporat pC every possible improvement so far developed by scientific research in the principles of variable condensers. Mini- ; mum amount of pure Bakelite used, consistent with: ADJUSTING NUT strength, to insure low dielectric loss. No current through bearings. In Combination Types, vernier and main rotor shafts absolutely independent, impossible for one to move the other.» Non-Magnetic material used exclusively. There is no such thing as a condenser being just as good as a Rathbun without these important advantages. es For Your Protection Look for this moulded seal appearing on every original Single Hole Mounting, low loss, uncon- ditionally guaranteed condensers. Prices for 3 to 43 Plate Types $1.00 to $6.00 © RATHBUN MANUFACTURING CO., INC. JAMESTOWN, NEW YORK BETTER SHOP METHODS DEPARTMENT OF POPULAR SCIENCE MONTHLY Filing Costs Cut by Use of Lathe Attachment By Frank N. Coakley HEN much filing is to be done ing small shop, the homemade filin machine illustrated will be found a great saver of time. It is designed to be driven by a lathe, and the construction is simple strong, and inexpensive. 4 The main body is a piece of oak 8 jn, thick, 74 in. wide, and of a length to suit the width of the lathe bed. The crossheag is made from a piece of 1}4 by 13; in, steel, 3144 in. long. This block is slotteq as indicated to allow the crosshead block to slide in it, and it is also slotted on the opposite side to fit a 5-in. square bar, This bar, which is fastened securely to the crosshead, is turned down to %-in, diameter at both ends to allow it to slide in the two solid “dead-eye” bearings, which are standard bearings and can he purchased at low cost. The bearings are 4 \FACEPLATE é steniine x CROSS*HEAD BLOCK FLAT-HEAD SCREW LEFT-HAND THREAD FACEPLATE PIN Front and left-hand views of the filing machine, and detail of faceplate pin fastened to the wooden body with through bolts. The upper end of the %-in. bar is drilled to receive the end of the file, which is held in place by two small setscrews. Back of the crosshead and fastened to the main body is a brass plate against which the crosshead slides. To support the table a piece of 2 by 2 by 14 in. angle is fastened to the top of the body with two lagscrews. A 15- or 3¢-in. hole is drilled near the top of the vertical leg of the angle. : The table is a piece of 3/16- or }4-in. plate smoothed and polished on the upper surface. A slot is provided to allow the file to pass through. To the under side of the table a three-cornered piece 15 riveted with countersunk rivets. A round extension projects from one side of this piece and is threaded so that it can he fastened with a nut to the table bracket. | This arrangement allows the table to be tilted. The machine is fastened to the lathe bed with a hanger screw and a piece of flat plate. . The stroke of the machine as shown }s 2 in. A longer or shorter stroke may be obtained by moving the faceplate con nection in or out. If a much longer stroke is used, the bearings will have to be farther apart. THE best method for locating holes - curately in jigs and dies will be so plained in an article by H. L. Wheel scheduled for early publication.

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lone in a de filing 1 a great e driven S simple, ak 3 in, h to suit rosshead 13% in, 8 slotted ad block d on the are bar, ly to the » Yin. to slide earings, | can be ings are ing pin y with bar is , which Screws. l to the ; which by 2 by of the r 5¢-in. vertical 3 1/-in, > upper ow the er side iece is round of this can be racket. 2 to be e lathe iece of 1own is nay be fe con- stroke farther les ac- be ex- heeler, ae _rAo= RADIO VACUUM 10R TUBE TYPE A isa storage battery tube for use as audio frequency and radio frequency amplifier in all standard circuits. Highly recom- mended also for detector use. This tube is not critical of adjustment either as to plate or fila- ment. Filament consumption one quarter of an ~ ampere, The most notable feature of the new Magnavox Radio Tube consists in eliminating the grid. Unlike the ordinary storage battery tube, Mag- navox Tubes give the electrons an unobstructed passage between filament and plate, with the result that the Magnavox has less than one half the internal capacity of other tubesof similar type. POPULAR SCIENCE MONTHLY | 109 i. a 84 Sn De ae See ea ine og? rf: Be fe OR - Peighte ae ‘ees eR BH Se ree pee * Fi Bess 9 2 — Tube HE engineers who developed the famous Magnavox line of radio reproducing and amplifying equip- ment have now produced a vac- uum tube equally distinctive and successful in its own field. One trial convinces the most exacting user that the Magnavox will replace ordinary tubes to great advantage in any receiving set. Magnavox Products Power Amplifiers for audio- frequency amplification, one, two, and three-stage; $27.50 to $60.00 Vacuum Tubes: A storage bat- tery tube of new and approv- ed design for all standard cir- cuits . j ‘ $5.00 Reproducers of electro-dynamic and semi-dynamic type, for all vacuum tube receiving sets; $25.00 to $50.00 Combination Sets combining a Reproducer and Power Am- plifier in one unit; $59.00, $85.00 Magnavox Radio Products are sold by reliable dealers every- where. If unacquainted with the Magnavox store in your vicinity, write us for information. © The name Magnavox is your as- surance of quality and efficiency. THE MAGNAVOX CO., OAKLAND, CALIF. NEW YORK SAN FRANCISCO Canadian Distributors: Perkins Electric Limited, Toronto, Montreal, Winnipeg

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110 HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY TRIMO The PipeWrench For Men Who Love Fine Tools In Steel Handle— All sizes from 6" to 48". In Wood Handle 6, 8, 10, and 14 inch sizes. It’s good to grip a TRIMO. You feel ready for any job, it’s such a finely built, powerful, capable wrench. Here are some of the reasons why Popular Science Institute of Standards endorses the TRIMO and why you'll find it one of the best tools a man Can own: Drop-Forged jaw and handle and pressed steel frame that does not break. Strip-Proof Threads in nut and in. movable jaw, rounded top and bottom, guaranteed not to strip or burr. Nut Guards to keep adjustment perfect when working in close quar- ters. Insert Jaw in handle. Can be readily replaced when dull or worn, making the TRIMO the most econ- omical wrench, since it lasts longest. You'll find the TRIMO Pipe Wrench one of the most serviceable, likeable tools you’ve ever used. Ask your dealer for a TRIMO. Accept no substitute. NOTE: When you need a Monkey Wrench, Chain Wrench or Pipe Cutter ask tosee a TRIMO and judge for yourself as to quality and value. 7106 TRIMONT MFG. CO. ROXBURY. MASS. How to Fit New Piston Rings By Ray F. Kuns Author of “Automotive Trade Training’’ a Y OLD 1917 bus runs like a top since I put in those new rings according to the directions you gave me last month,” said a friend the other day. ‘*Several of my neighbors had tried new rings that did not seem to do much good. I hunted all over town and finally did find them. I had to get .007 in oversize on the width, as the ring grooves were worn tapered, and I had a time to fit them, but I finally got them fitted and now I have to keep the brakes on most of the time to hold the old wagon.” This literal repetition of the owner’s statement tells the whole story. Here is an owner who likes to maintain his car in good running condition by doing his own repair work. His equip- ment is that of the average home ga- rage; his problem that of fitting new rings into piston grooves worn ta- pered by long ser- —_—__— SHEET OF EMERY CLOTH : lathe or with a Piston. | groove cutting tool, o- | failing this, observe the | instructions given ™ detail below for filing to a fit. . Estimate the oversize of the cylinder diameter. Unless previously rebored or reground, this may run from .005 to .019 in. Usea feeler gage to learn the amount of wear in the piston-ring groove; the top one usually has most. From these figures order the rings. As to what type of ring to purchase, that is largely a matter of per- sonal opinion—one piece, two Piece, or three piece; bevel, step, or patented joint —the success of the rings rests in the three points mentioned above. With the rings at hand, test them to see that they are properly oversize and not too large, or that too much « work is required and a fit js impractical, Knowing that they are the proper size, they are fitted to the cylinder they are to be used in, This means filing the end joints until vice. In the service garage, it is likely that the pistons would be discarded in favor of new ones, and rightly so. At least the ring grooves would be trued up in a lathe or with a special tool. the proper clear- ance is obtained. When testing the ring in the cylin- ders, hold a drop- light under them and note if they lie in even contact with the cylinder walls. If they do not, it is useless to The first thing this owner did was to find the rings he needed. It is easy to find rings hav- ing the proper oversize when con- sidering cylinder diameter, but a bit harder to find the ones with the oversize on the width, and in this case, that was ab- solutely essential. ° Having the rings, he then proceeded to fit them. The most important consideration in fitting rings is to have a ring that lies in perfect contact with the cylinder walls. The next is to have a ring that fits the piston groove, and the third consideration is to have a ring in which the end clearance is not excessive. There are others, but if these three have been met satisfactorily, the owner is reasonably sure of a satis- factory job. First, remove the pistons and connect- ing rod assembly, being careful to main- tain all shims and bearings in order. Next, use three thin strips of steel to slip under the rings and slide them from the pistons —hacksaw blades or old case knives do nicely. Remove all carbon deposits from the piston-ring grooves and clean thor- oughly. Inspect the rings and grooves for evidences of wear. If the grooves are worn tapered, have them trued up on a ROLLING PISTON RING IN GROOVE Grinding a ring, testing it for width and concentricity, and filing it to fit the groove attempt to fit them. While rings may be lapped to a fit with the cylinder walls, that is not always advisable. The best fit is se- cured when a lathe-finished ring has been properly peened or has proper tension to fit the cylinder walls at first hand. When the rings lie against the wall properly, the ends are filed to allow proper clearance between them. The top ring has .002 in. allowed for each inch of piston diameter; the lower rings half this amount. Next, fit the ring to the piston- ring groove, fitting individual rings to individual grooves, and maintaining them in that position. The first step in fitting rings to grooves is to roll the ring around the piston with the outer edge of the ring in the groove. If the grooves are true, practically all the fitting may be done in this fashion. Where the grooves are tapered, the first step is as above, and if the ring should be too wide, reduce it by means of a piece of emery cloth laid on a piece of plate glass or other true surface until it just starts to enter the groove. With a file, carefully reduce the inner edges of the ring until the ring is tapered to fit the (Continued on page 112)

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tia S | Piston. tool, or, eT Ve the iven jy cylindey 0red or to .010 amount the top @ figures > of ring T Of per. lece, of red joint 3 in the them to ize and 0 much a fit is tical, lat they per size, itted to er they ised in, S filing its until ' clear- ytained, ing the > cylin- a drop- r them if they contact *ylinder hey do eless to to fit gs may (O a fit ylinder is not visable. t is se- 1en a d ring operly has ion to ylinder hand. 2 wall allow he top nch of If this iston- gs to them “ooves : with roove. ill the , the . ring ans of ce of itil it ith a of the t the POPULAR SCIENCE MONTHLY Make the World of Music Yours HEN ‘a famous soprano sings the ‘Gypsy Song from Carmen, hear it in ‘your home exactly as she sings it. Through Music Master, the musical in- strument of radio, let her voice be crystal clear. Music Master gives to radio life and beauty, lending a wholly new charm to the wonders of the air. Music MasTER is not just a loud speaker it is a true speaker, a clear speaker, a pleasing musical instrument. Radio impulses entering the sensitive pre- cision instrument in the base are translated into sound waves, undistorted and faithful to the original voice or instrument. In the tapered tone chamber of cast aluminum these sound waves grow clear and bell-like and, finally, the full, mature tones pour forth in rich resonance through the Music MasTER amplifying bell of natural wood. Your dealer knows. Have him send you a Music Master to be proved with your own set. Dealers Everywhere {Music Master Corporation Makers and Distributors of High-Grade Radio Apparatus 10th and Cherry Streets Chicago PHILADELPHIA Pittsburgh Ul S il @ , Connect Music Master 14-inch Model, for $3() in place of headphones. the Home Sel 1 HF 21-inch Model, for $ i / Cl No batteries required. + pam oe 35 ‘| ie: No adjustments. Dancing RADIO REPRODUCER

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Illustration of file, actual size Newe Here it is, your handiest file. Just what you’ve wanted. The only file of its kind. It files everything, sharpens anything, with its two faces— double-cut (coarse) on one side; single- cut (fine) on other side. Two files in one. PLUMB DOUBLE-LIFE All-Work’ File with sheath *Trade Mark Reg. U.S. Pat. Off. Handle, forged as part of file, fits your hand, guides your stroke, saves your knuckles, makes work easy. Carry a Plumb AIll- Work File in your kit or in your pocket. Sheathcomeswith every file, to pro- tect the teeth from damage or rust. You want this file for every job around the house, . for your radio, to sharpen your knives and your tools. The better hardware merchants, who sell the latest good things, have Plumb All-Work Files for you. Only Seniors or by mail (40c west of Rocky Mts.) It’s no trouble to supply you if your dealer can’t. Just send 35 cents and we'll see that you get your Plumb AIll- Work File by the next mail. Your money back if you want it. FAYETTE R. PLUMB, Inc. 4810 James St., Philadelphia PLUMB DOUBLE LIFE HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY How to Fit New Piston Rings (Continued from page 110) taper of the ring groove. To test the fit of the ring it will be necessary to slip the ring onto the piston in its natural position rather than by the rolling process. Make quite certain that the piston ring will go into the groove at every point a distance to allow it to come flush with the outside of the piston. In all cases this must be looked to, or scored and frozen pistons and cylinder walls will result. In fact, it is well to measure the thickness of the new rings and compare it to the depth of the groove before starting work. There should be at least .005 in. back of the ring and .001 to .002 in. clearance in the ring groove. In final assembly it is well to go over all parts and clean thoroughly. Apply oil generously and assemble. If the car is to remain a considerable time before start- ing, introduce new oil into each cylinder to be certain of immediate lubrication. When the engine is first started, run it on the floor with a line of hose to the radiator to keep it cool. See that the oil pump starts immediately (if a pump is used) and have plenty of oil in the engine. Place a pint of oil in the first five gallons of gasoline, and while the engine is run- ning in, squirt a gunful of oil into the air intake of the carburetor each 10 or 15 minutes. After two or three hours’ run- ning, the oil should be drained and new oil used. Drain again after from 200 to 300 miles and after each 500 thereafter. Cheap Captive Golf Tee Most golfers who use a captive golf tee have to buy a new one every few weeks. They either are left behind on the tees or are broken. Although they generally cost less than a dollar, some golfers who are thrifty and like to make things may be glad to learn how to _ provide themselves with tees that cost practically nothing. As will be seen in the accompanying illustration, the tee is made from an old cork stopper, a lead dress weight, and a few inches of string. The small end of the cork is counter- —TEAD DRESS-WEIGHT sunk to afford a How the homemade better seat for the ‘ee is constructed golf ball. A small hole is made for the string, a knot on the end keeping it from pulling out of the cork. The other end of the string is tied to the dress weight, and the captive tee is finished.—F. S. Root, Fall River, Mass. Aa COUNTERSUNK OME WORKSHOP features sched- uled for early publication include: How to Duplicate an Early American Arm-Chair, Lighting the Attic, What You Can Do with a Vise, Timing Auto Engine Valves, A Simply Constructed Smoking Stand, How to Make Rush- or Flag-Bottom Chair Seats, Duplicat- ing Cheaply an Expensive - Fireplace Screen, A Handy Spice Cabinet, Secrets of Varnishing Furniture Successfully. ie One ONE PIECE STATOR One of Several New Features in Four New Types Stamped out of one piece of aluminum—th. one piece stator elimi. nates broken contacts and soldered joints, Pos. itive results—no leak. age. Found in types 3 and 4, celoron end plates, and types 5 and 6, low loss—metal end plates. Ask Your De Show You the reo Mood Stator and other Im. provements. . 00% Guaranteed Write'for Literature U.S. TOOL CO., Inc. 127 Mechanic Street, Newark, N. J. Mfrs. of Special Tools, Dies, Jigs, Automatic Machinery and Sub Presses, : as shines y , Sas So Handy OU will say so just as others have as soon as you see the Simore screw- driver or combination knife and screw- driver. Model No. 11 has three screw- driver blades, No. 12 has a fine steel knife blade and two screwdriver blades. Both tools unusually useful around the house or car, or on a camping trip. Blades are selected and produced by gravity action thru the chuck, and cannot be lost, or misplaced. When in place for use the blades are rigid and dependable. Handle blued to prevent rust. Model No. 11 for $1.80, and No. 12 for $2.25. Send money order or your check and we will ship post prepaid at once. Each tool guaranteed, and your money refunded if not satisfactory. Dealers are requested to write for information on these tools and the Simore Automatic Try square. THE SIMON & SKIDMORE MFG. C0. Dept. 5-10 Santa Ana, California e Saw Books FREE **Saws in the Shop,” “Saw Sense,’ “Saws on the Farm.” Just send us your name and address and say which of these helpful books you want—Free. Write NOW. E. C. ATKINS & CO., Inc. Dept. D-20 Indianapolis, Ind. 1S) - “WONDER” COLD PIPE, TUBING & BAR BENDERS HAND and MOTOR OPERATED 14 Sizes of Machines ah ages . Per : Y’' pipe Scents 4’° pipe 25 2’’ pipe 10. cents D coats ts Oe ” & Send for Catalogue. AMERICAN PIPE BENDING MACHINE CO. S1 Peart St. Boston, Mass.) con

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Pei umber One TOR tures of one im—the r elimi. contacts its. Pos. 0 leak. SS and tal end aler to ne Piece er Im. sl (7 ALS a) ————— ———— Soft Mellow Light You attach the light cord to any socket and switch on a soft glowing light. Then and there you will be convinced that you have the most beau- tiful library lamp money can buy. POPULAR SCIENCE MONTHLY ae} £ Ni MY f Spectal loud Speaking unit 113 Clear Resonant Radio Tone Simply attach the Radia- lamp in place of the head phones. Then switch on your Radio set. Instantly the room is flooded with music sO amazingly clear—so flaw- lessly resonant--you will wonder that any Radio loud speaker can give such per- fect reproduction. No. extra batteries—no adjustments. azing New Twin-Feature ¢ is RADI ; have screw- 3 L] ; crew , ' > steel ae. > ; ates HERE have been ~ orn Two Superior Features “60a if a already ie an a the ” : ° ° oud speaker you will also want the type’ loud speakers, box P be spa ; . a p Peer 8 gee cal For the Price of Either RApIALAMP for its beautiful music e lost, k r viele > aha As a loud speaker alone compare the and its excellent reading light. -You 5 ca spea ers—but never before in| RADIALAMP with any of the old- can put it in another room—if you 7 the history of Radio has there type horns. Examine it carefully—see wish to. Eastly connected by a long ‘het been such a sensation as the latest scientific prin- wire to your receiving set. ach j i = ° funded the RADIALAMP. It DEALERS ciples that make it a su Step in to your dealer to-day—see the . isa loud speaker. It is San Cn tak a Oh perior Radio horn. From RApJALAMP for yourself—you will he a library | Al This Radio Sensation | the loud speaking unit con- be won over instantly by its astonish- ' ry ijamp. sO cealed in the base the tone : ge Pm : - 00 teen iaih ‘babl arpit this beautiful tamp | ified th ee ing beauty—it will positively add to . INGESCTIDADIY | hnter and ell tt forthe | 28 Amplified through the she grace and charm of the alread fornia better loud speaker, from | price of either @ good} tapered tone chamber to . hi nel A sear lamp or loud speaker— “i ri eee a lovely furnished home. As an art piece b perfected unit in the as. us ae cone the “sound mirror in the —you will see that it is in a class by EE ase, to the taut parch- See the radio fans collect top of the shade. Here it is ‘seek sad the vsice--the ee hade th oases —watch them stream in to defl d i I h- ? b } : ss onan’ ment shade that gives it the ask questions, see fhem emecte into the parc LAMP is a superior lamp and loud t send flawless, human tone reso- cnn a Milas ment shade through the S ker for th sual i f either which nance And it i . is lighted and they can 2 ir which is k - peaker itor € usual pr ce 0 € . 1s an in- appreciate the soft, mel- Warm alr W 11CNn 1S ept at a ss a b fill Free. ; : ane Se ot. wee : one. If your dealer hasn’t it, just fill in romparably more beautiful oe bates was toreme | uniform heat by the light 2.3 25 the coupon. It will bring baa amp, from the artistic cast tion, (Thousands are buy’ | globes. The sound waves you complete information tats metal stem to the light- | Yow. Jt sill make just | are intensified by the warm “ “PIPE, nellowing shade madeof spe- Witte See Suriher Sntee- air which greatly increases Radiolamp Company Re dally selected parchment. the purity of the tone. pent. 210, 234 Fifth Ave, New York PERATED ON SALE AT LEADING RADIO STORES EVERYWHERE WRediolamp Co. Dept. 210. 1 a 3 nines : on i 334 Fifth Ave., New York. sil Bo Please send me at once complete information pe 25 cea \ bY A about RADIALAMP loud speaker. r CO. a bed ee 1 INNES 6-dic-n:a cardbt'ee 6 0 s:e:cs0.wcrin's'eac we amolbe temas — MARKT = UD SP E R E.G Soe err rerrr rrr ror cL

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-No.81 sticking. size marked plainly. will endure. tool, At your dealer’s. COMPANY Millers Falls, Mass. New York Chicago MILLERS FALLS | TOOLS ; Specifications Eight drill points Improved ball chuck Improved shell; can- not be completely unscrewed and lost Handle handsomely knurled Spiral nut of Tobin bronze Highly polished and nickeled overall Length1034”". Weight, each, 9 oz. Tacked one in a box. HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY Bore Holes T’S new. We've built this drill difference into it. Hard wood tests drills. Smoothand clean No.81 makes itstwisting cut into hard wood—no Simplicity— another of No. 81’s virtues. It’s easy to get out the right drill point. Just loosen the knurled magazine nut—the handle slides down the frame, exposing the points. Each drill point has itsown pocket—numberand The handle fits the hand » comfortably. The whole tool is polished and nickeled with a bright finish which If you don’t own an auto- » matic drill you need No. 81. If you do—you'll quickly see the difference in No. 81. Another good Millers Falls | MILLERS FALLS 28 Warren St. 9 So. Clinton St. Easily Built Radio Cabinet (Continued from page 85) ‘Show me,” I said, “‘something that looks really well and yet can be made without mortises and tenons and dove- tails and dowels and a whole lot of time- consuming cabinetwork!”’ He took up my challenge without hesi- tation and a few days later sent me a blueprint, with this letter: *Inclosed is a blueprint of the radio cabinet I was speaking about on the train the other day. With the exception of the crude ‘soapbox’ furniture that was written about so much a few years ago, it is about the easiest piece to make that has been designed. Any one able to make a box can construct it, and with the experi- ence you have had in doing odd jobs around your house, you won’t have any trouble at all. “The cabinet will hold your present radio set as it is and leave room in the back for your dry cells and your table talker. If you buy the big horn you have been talking about, you can place it on top of the cabinet. “The details of construction, I might add, were worked out by George F. Kaercher, of Philadelphia, who has de- signed and supervised the construction of fine furniture for many years and whose firm has made hundreds of thousands of radio cabinets and wooden horns. ‘All the joints are plain butt joints— the kind you’d use in making a box.” The reason the cabinet looks so well: when finished is because the upper part is made of five-ply mahogany or walnut veneer. This is the material the furniture manu- facturers use so much and every home woodworker certainly should take full ad- vantage of it. aS i! THE first place, you buy it in large sheets, usually 30 or 36 in. wide and 60, 72, or 84 in. long. These sheets can be had with either one or both faces covered with choice veneer, often with fine figures —the sort of wood you see in expensive furniture and the paneling in shop win- dows on Fifth Avenue. “The surface is smooth and perfect— it has been scraped and sanded to a finish that the amateur woodworker can rarely equal, even with the most painstaking work. Nothing whatever needs to be done to it except to cut it up and use it; and, of course, you can use as large pieces as you please without the work entailed in gluing together and cleaning up solid boards. Besides, this five-ply veneer holds its shape well; it doesn’t crack or check or twist as so much solid woodwork does, especially as put together by ama- teurs. Finally, the veneer takes a splendid finish. You can make a professional- looking job with it, and do it easily. “You will see that the cabinet is orna- mented with overlays of thin veneer. Such ornamentation is now popular on commercial furniture of high quality, and, luckily, it is about the easiest decora- tion the amateur can apply—far easier than carving, inlaying, or even painting on decorations. And there is a great ad- vantage in the use of overlays—they will cover the unsightly joints. Notice how the overlay around the edges of the ends covers and hides the plain butt joints. "|- ‘Making these overlays is really the same as the fretsaw work taught so gener- ally in the lower grades of grammar schools. Get some thin veneer and glue it with the best quality of liquid glue or good hot glue to tough brown wrapping paper. Let it dry under pressure. You do not (Continued on page 116) Next time you get a chance, ask the fellow who is a ‘‘crank’’ about fine tools, to let you look at his assort- ment of Klein’s. Pick up a pair; feel the easy way they balance; note the shape and spring of the handles, that make them easy to work with for hours without cramping; try the keen knives—get the hang of a fine plier in your own hands! tao on 10) pa Any hardware distribu- tor has them—just ask for Klein’s! Klein’s “Pocket Tool Guide” is full of useful tables for the electrician. Drop usa card for one. It's free for the asking. 3220 BELMONT AVENUE 1S) CHICAGO, ILL. aan KLIEDNa

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POPULAR SCIENCE MONTHLY These Exclusive Features Assure Better ‘Reception The shellis ORANGE Bakelite — the base genuine Thermoplax At Last—A Radio Socket Worthy of This Famous Trade Mark OR EI prong cleaned when inserted—-no contact or wear on soldered end. After months of experiment and research the Cutler-Hammer . ° ° . ° ° B engineers announce this masterpiece of radio socket design. With All metal parts silver plated— features never before found in any socket, it brings to your set a perfect contact for the life of the set. f Silver may tarnish but its contact degree of efficiency that means added miles of range and hours resistance does not change. of clearer, more enjoyable reception. c - ale . . One piece contact construction. Capacity has been absolutely minimized—without sacrifice of The binding post is NOT a part of > . : the circuit—the wire to the socket mechanical strength, and its base of ebony black Thermoplax in sinuses: snditadha ania beautiful color contrast with the thin shell of orange Bakelite whick carries the current direct to J : the tube prong—no joints to cause adds as much to the appearance of any set as this socket’s con- losses. . e es D struction does to its efficiency. Convenient terminals for solder- 3 rs - - ing —full length to allow bendin You'll like all of its many exclusive features—the silvered ae aaane Sane ait bronze contacts that afford sermanently perfect contact; the slot- wire in place for soldering. ‘ ide ' : ; St ; - is ; ted binding nuts; the handy terminals for soldering; the wide spac ee ae to Ing of current Carrying parts. connections with either wrench or t P : , ' , ‘ screw-driver. Lock washers hold , You'll like its appearance—neatness—small size. You'll like the terminals rigid. se - fe F ss way the tube is inserted and removed without twisting. And best Wide spacing of current carrying 5 , . . ° both in air and insulation = parts ot. Tra ula 1 ad of all, you'll like the price, goc. r. his socket that meets the specifica Se ee a tins of the most exacting radto engineer costs no more than most of those o ai on the market today. Until all dealers have been stocked, you can _ A minimum of both metal and . m , ; insulation for low capacity. Shell of 4 be supplied direct from the factory at the retail price plus 10 cents thin Bakelite—the base of genuine - or packing and postage. Be sure you have the genuine—it will er t ° - ° . } pay you in every way to refuse all substitutes. The tube is held in place by merely a vertical motion — no k : twisting to separate bulb from base. THE CUTLER-HAMMER MEG. CO. ; The attraétive orange shell helps IS) Member Radio Section, Associated Manufacturers of Electrical Supplies ped oe 8 poe Cyne —— MILWAUKEE, WISCONSIN . ey oy Soe apa genuine protection RADIO SOC KET

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Ly & “Experience is the Vital Factor in Excellence™ | The first “talking machine” became a finished reproducer of speech and music only by years of experience devoted to gradual development. GnOOPsON SPHAKHER. Fourteen years devoted to making radio products furnished the background from which the Thompson organization has perfected the Thompson Speaker. Each part of the Thompson is the result of the best known engineering experience and these parts are assembled in a manner that is possible only to experi- enced radio engineers. The 7 superior and distinctively Thompson features are seven reasons why you should not ‘‘Just get along” with an ordinary speaker when you can get a Thompson. $28. * * 7 . * *

Few users ever need all the range and power that the Thompson Neutrodyne Radio Receiver will deliver. Made by the same organization. Now $125 without tubes or batteries. R. E. THOMPSON MANUFACTURING CO. Manufacturers of Radio Apparatus for the U. S. Army and Navy and numerous foreign governments 30 CHURCH STREET « » NEW YORK,N. Y. FACTORY: JERSEY CITY, N. J.

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TWENTIETH CENTURY Book of Recipes, Formulas and Processes This book of 800 pages is the A mine of information, up-to- most complete Book of Recipes date in every respect. Con- ever published. Hints, Helps, tains an immense number of Practical Ideas and Secret Proc- formulas that every one ought esses covering every branch of to have that are not found in the useful arts are given. any other work. Price, $4.00 Popular Science Monthly, 250 Fourth Ave., New York

Easily Built Radio Cabinet (Continued from page 114) have to glue it on paper, but I have found that it is desirable to do so in most Cases because there is so much less danger of | cracking the veneer or breaking off deli. | cate corners in sawing. ‘| “You can join several pieces of the | veneer, one on top of the other, with touches of glue in what are. to be ‘waste’ | parts and, after marking the outline oy the top, saw them out all at once. Use fine fret- or coping-saw. A sharp knife also ean be used for cutting the veneer, jy which case it is well to moisten the veneer a little first. The miters and straight lines can best be cut by means of a knife and straight-edge. “Then, to apply the overlays, you have two methods. One is to use cold liquid glue, not too thick, and spread it on the veneer or on the brown paper, if you have paper on the back of the veneer. Lay it | aside with the glue exposed for about 10 | minutes. Then put it in place and press it down well with a hammer or fiatiron. The other method is to use hot glue, in which case the overlays are applied im- mediately and pressed, or ‘laid,’ as a shop man would say, with a hammer. “The front edges of the box part of the cabinet may be covered with veneer put on like the ornamental overlays; this makes the best job. You can make square joints where the strips meet at each corner or miter the joints, as you prefer, Trim the veneer and round the edges a trifle with sandpaper after the glue is dry. “TF YOU don’t want to go to the trouble of veneering the edges, you can paint them with a brown enamel or with shellac colored opaquely to match the final finish; but to my mind that would be as much or more trouble than using the veneer. “The stand is made of %-in. stock throughout and the parts are glued and nailed together with finishing nails. You can use screws from inside to fasten the legs to the upper rails, if you wish, but the nails and glue will serve. “In finishing, you can get easily the modern two-tone effect—the body of the stand and case being one tone and the overlays either lighter or darker. An easy way to accomplish this is to apply either walnut or mahogany oil stain—better use oil and run no risks of accidentally blistering the veneer or loosening the overlays—to either the over- lays, if you want them darker than the rest, or to everything but the overlays. Then dilute the stain as directed on the label to lighten it considerably, and stain the whole piece. Fill the wood with either walnut or mahogany colored paste filler, or color some natural paste filler with a little of the stain you have used. Be sure to rub off the filler well, across the grain. Next, give a thin or wash coat or shellac to ‘fix’ the stain. “ After that, there are several methods of procedure. One of the best is to give several coats of shellac, and sandpaper each lightly with 00 paper, preferably a well-worn piece. Then finish with one or two coats of furniture wax, put on thin and polished long and briskly. Another method is to use one coat of shellac and two coats of varnish. The last. coat df varnish should be rubbed with fine | powdered pumice-stone and oil. “‘Kither of these finishes, if you use| good material, will last and look well for | half a century or more. Indeed, finished | in this way, the fine cabinet woods im: | prove with age and get more mellow ane | beautiful.” (Continued on page ny |

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' Veneer straight a knife DU have | liquid on the | u have Lay it out 10 d press latiron. flue, in ied im- ” asa mer. ; of the er put > this square t each prefer, dges a is dry, rouble . paint shellac finish; much eer, stock od and . You en the h, but ly the of the id the . An is to ny oil isks of er or > over- in the orlays. ym the | stain with paste - filler used. ss the oat or thods ) give paper bly a yne OF . thin other ce and vat of fine 1 use 1] for ished s im- y and = | Easily Built Radio Cabinet (Continued from page 116) So there I was, well launched into my cabinetmaking venture. The first thing I did after studying the blueprint, was to go over the bill of materials, which was as follows: rpc. 56 by 18 in. by 2 ft. 4 in. five-ply veneer, ma- “"hogany or walnut faced on either one or two sides, for top and bottom of case. — ape. 5 bY 17 54 by 16% in., same material, for ends. 2 pe. 56 by 13%% by 1634 in., same material, for ors. 1p 86 by 1634 in. by 2 ft. 4in., three- or five-ply veneer, mahogany or walnut, for back. ape. % by 2 in. by 2 ft. 314 in., mahogany or walnut "~ (golid, not plywood), for front and back top rails. rpc. % by 134 by 1534 in., same material, for top * “end rails. . Py * by 2%4 in. by 2 ft. 4 in., same material, for facing of legs. : . spc. % by 15% in. by 2 ft. 4 in., same material, for returns of legs. ; ; pc. %-in. quarter-round molding 2 ft. 24 in. long, mahogany or walnut, for filling pieces inside legs (optional; may be omitted). 2pce. % by 134 by 13% in. mahogany or walnut, for bottom end stretchers. . ipe. % by 134 by 20% in., same material, for bot- tom center stretcher. : 1 pe. 2 ft. wide and 2 ft. 6 in. long, thin mahogany or walnut veneer, for overlays and to cover front edges of box. 2 pr. ornamental hinges, brass. 2? door knobs or pulls. ; j 2 ball-eand-socket catches, % in. in diameter, for doors. Glue, nails, and screws. I saw that there really wasn’t much lumber needed—a sheet of 5-in. veneer 3 ft. wide and 6 ft. long and a small piece s¢-in. veneer for the case, and a board for making the stand. My own lumber dealer had some mahogany on hand and I got a board 6 in. wide and 12 ft. long— more than enough to cut the stand. He didn’t have any plywood, however, al- though he said he probably could get what I wanted in a week or two. For the moment I was tempted not to bother with plywood, but to make the case from solid lumber, as it would be so easy to do, but I decided not to deviate from the original plan. The next day I dropped into a lumber yard in New York and was taken up a ladder to a sort of loft, where I was shown immense stacks of plywood of all kinds. We couldn’t find any mahogany pieces % in. thick. There was plenty of 4% and 7/16 in. I was on the point of taking a piece of 14-in. mahogany veneer, beauti- fully marked in a sort of fiddle-back pat- tern, when I stopped and asked the price. It was 60 cents a foot for a 3 by 7 ft. piece, or $12.60. I thought that was pretty high, so did not take it. My next effort to get the veneer was at a veneer factory in a town near my home, and there I got exactly what I wanted for 45 cents a square foot, and a piece of 3-ply stock, 34 in. thick, for the back, only one side mahogany, for 30 cents a square foot. These were cut up the exact sizes I wished, so that the making of the case was merely a matter of nailing the parts together. I took no chances on splitting the wood, but drilled holes first. In laying out the parts for the stand, I found that by turning the legs end to end and laying them out one within the other, as it were, it was possible to economize material. I sawed the wood up just out- HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY side the lines, using my crosscut and rip Saws for the straight lines and a narrow Compass saw for the curves. Then, with a cabinet rasp, I completed the curves (Continued on page 119) We Amaze Men With this Shaving Cream, whatever they expect By V. K. CASSADY, Chief Chemist GENTLEMEN: Our claims for Palmolive Shaving Cream sound almost too good to be true. But they tempt millions to ask for samples. Then comes the test. Our cause is lost if we fail to make good on these claims. We do make good. This Cream has become a sensation. Just because we learned the five things that men wanted most. We worked 18 months to excel in those things—made up 130 separate formulas. Now give us a chance We offer a Shaving Cream which millions like. So will you regard it. We ask you to accept a Ten-Shave Test to prove the claims we make. It may mean new shaving delights. 1—Multiplies itself in lather 250 times. 5 2—Softens the beard in one minute. 3—Maintains its creamy fullness 10 minutes on the face. Delights 4—Strong bubbles hold the hairs erect for cutting. 5—Fine after-effects, due to palm and olive oil content. To add the final touch to shaving luxury, we have created Palmolive After Shav- ing Talc—especially for men. Doesn’t show. Leaves the skin smooth and fresh, and gives that well-groomed look. Try the sample we are sending free with the tube of Shaving Cream. Clip coupon now. THE PALMOLIVE COMPANY _(Del. Corp.), Chicago, IIl. PALMOLIVE SHAVING CREAM _ and a can of Palmolive After Shaving Talc Simply insert your name and address and mail, Address for residents of Wisconsin, The Palmolive Company (Wis- Corp.), Milwaukee, Wis., Dept. B-906. Address for residents other than Wisconsin, The Palmolive Company (Del. Corp.), 3702 Iron St., Chicago, IIl., Dept. B-906.

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a The Drill that works where 9 others can’t! HEN small holes must be drilled, in places too cramped for ordi- nary drills to operate, call on “YANKEE” Ratchet Hand Drill No. 1530 Even when you can move the crank only an } inch one way or another in tight corners, the “Yankee” DOUBLE Ratchet keeps the drill cutting continuously. There are five adjust- ments, changed by a finger touch on ratchet ' shifter: (1) Plain Drill. (2) Left-hand Ratchet. (3) Right-hand Ratchet. (4) DOUBLE RAT- CHET. (5) Gears locked (for changing drills). Although only 10% inches long, and weigh- ing only 114 lbs., this little “Yankee” Drill is built along the same lines as the big “Yankee” Ratchet Hand and Breast Drills. 3-jaw chuck holds up to 3/16 in. Some other ‘‘YANKEE” Tools Spiral Ratchet Screw-drivers Ratchet Bench Drills Ratchet Tap Wrenches Automatic Push Drills FREE Tool Book ' Write for your copy of the “Yankee” Tool Book. All ; the ingenious “Yankee” Tools are pictured and described within. Dealers Everywhere Sell ‘“‘Yankee’’ Tools » North Bros.Mfg.Co.,Philadelphia, U.S.A. “YANKEE” TOOLS Make Betlov Mechanica HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY The Home Shipshape_ ae THE importance of taking proper care of window screens can be illustrated by the experience of a friend of mine who owns 15 medium class one-family houses. To these homes every spring he sends a truck and gathers up from 75 to 100 screens, all requiring repair and many needing new wire. Yet in his own large residence practically no replacements have been made in the last 10 years. The reason for this is that in his own case the man in charge of his grounds takes proper care of the screens, whereas, in the case of the tenants, with a few ex- ceptions, the screens are taken down care- lessly in the fall and thrown into any va- cant corner of the cellar, uncovered and unprotected un- til they were needed in the spring. When you take down the screens, gather all the loose screws, hooks, but- tons, and attach- ments and tie them securely in a piece of canvas, fastening the bundle to the handle of one of the screen doors. See that each screen is marked so that it can be replaced without waste of time next spring. The simplest and _ best method with which I am familiar is to mark all outside screens with Roman numerals cut with a 14-in. wide chisel. I prefer to mark on the left-hand edge of the window screen (looking through the window from the inside), about 2 ft. above the window-sill. The outside window-casing is marked in the corre- sponding position with the same number. It is surprising what an aid it is to number all the screens on the same side and about the same height from the sill. If one doesn’t care to mark the wood- work in this way, as, for instance, on cer- tain styles of inside screens, metallic num- ber tacks, which may be purchased cheaply at any hardware store, may be used, or the bottom of each screen may be marked with a heavy colored marking crayon, the designations being “B.R. Front” or “‘B.R. South,” meaning bed- room front or bedroom south; ‘“D.R. East,’”’ meaning the east window of the dining-room, and so on. If different colored crayons are used for different floors, the sorting out is facilitated. A good crayon mark on the bottom of an inside screen will remain visible for years. When the screens are down, brush them well, doing the work outdoors and keeping Caring for Fly Screens “= winoow NUMBER ‘= ON SCREEN your back to the wind so that the dust will be carried away from you. While doing this, note carefully whether any of the screens have a brown or slightly rusty look. These should be placed at one side for painting at the earliest oppor- tunity; the wire may be past service jf left until spring. Asphaltum varnish, which is so useful both for preserving metal work and for use as a wood stain, may be used for painting the wire, or use regular black or green screen enamel. Boiled linseed oil to which a little lampblack has been added also is excellent, and this may be applied either with a brush or a small piece of close-grained sponge. If any tears or holes are seen, they may be repaired readily, if not too large, with small screen wire patches, the edges of which are un- raveled and caught in the screen. Usually it is im- possible to repair a “run” or tear along the line of tacks. In such a case, even if the wire is otherwise in good condition, it is best to put on new wire. The pieceremoved may be used for covering a smaller screen. The screens should be packed together as closely as possible, on edge, and covered completely with cloth or strong paper. It is best to store them in the attic ora storage room. If they must go in the cellar, they should be put on a rack well off the floor.—A. E. ELLING. How to mark and store door and window screens THOSE who have Felt-Covered hardwood floors in Rockers their houses know , the difficulty in keeping them free from _ furniture scratches. Pushes and slides overcome the difficulty for furniture that kas straight legs, but these will not prevent rockers from scratching the floor. I have found the best thing to do with the bottom of a rocker is to glue on a strip cut from an old felt hat. Don’t let the joint come where the rocker rests when idle. The felt lasts a long time and can be renewed easily when worn.—H. C. ies A coop furniture Polishing polish for general Furniture use is: One half pint of raw linseed oil, three tablespoons of turpentine, two tablespoons of grain or wood alcohol, three tablespoons of vinegar. Shake well before using. It may be used on the finest finish and will produce a rich gloss.—H. L. W.

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> dust While any of ightly ced at OPpor- Vice if useful nd for ed for ack or | oil to added pplied ece of Lined ars or 1, they paired ot too small wire edges ‘@ un- caught \. is im- pair a r along . case, 1 good n new e used gether vered paper. c ora in the k well have ors in know y an niture rcome > kas event ) with . strip >t the when ‘an be niture eneral half nseed , two three yefore finish L. W.

Easily Built Radio Cabinet (Continued from page 117) | where they were roughest and smoothed them with a spokeshave, scraper, and | sandpaper. The other surfaces and edges | were smoothed with a fore plane and a smoothing plane, although I could have done it all with the smoothing plane alone. J glued and nailed together the legs first of all, then fastened the legs in pairs with the end rails and stretchers, and finally put the whole together. HEN it came to buying the thin veneer, I suppose I might have dropped into the shop of the old cabinet- maker in my own town, because he, no doubt, uses veneer in repairing antiques, but I looked up the New York telephone directory and found a firm that specialized in veneers andinlays. The workshop was on one floor of a loft building overlooking the East River—a rather rambling collec- tion of workrooms, littered with an amazing profusion of veneers, bandings, inlays, and fretwork of many kinds. There I obtained a very fine sheet of thin mahogany veneer at the rate of 30 cents a square foot; plain, unfigured veneer was obtainable for 25 cents. The veneers were prepared just as I had been told and cut out with a coping-saw. It was much less work than I had expected because I was able to cut four thicknesses at once. While sawing, I supported the work on a board with a V notch in the end; this was clamped so that the notched end projected from the bench top. In gluing on the veneers I used liquid glue and was not a little astonished at how well the pieces stuck after the glue had set for five or 10 minutes. Next, I put on the hardware, fitting the doors a little with a plane where necessary and placing a small block at the top and bottom to serve as a stop. To apply the ball-and-socket catches I found it was necessary only to bore \4-in. holes in the case and push in the catches, screwing the corresponding strik- ing plates to the doors, where the ball- lixe projections would catch in them. I fastened the box part to the stand with | four small brass angles. A’ ABOUT this stage, my wife was willing to admit that the cabinet looked like a piece of realfurniture. Before this she had been more or less skeptical. “Do you know,” she said, ‘‘I think it could be made into a very nice desk. I Saw one along the same lines—a box on | legs—in a furniture store. Instead of the | doors it had a single lid, hinged at the | bottom; when open it was the writing | table.” Another suggestion she made was that I build another stand exactly the same and put a plain top on it, with an inch or two overhang on each side. | “It would be just the right size for the little sewing-table I have been wanting to get,” she explained. _ The finishing was the most tedious and, if anything, the most difficult part of the | Whole work. I stained everything but the overlays a brown mahogany. Then I gave the entire cabinet a coat of thinner stain, puttied the nail holes with colored putty, | and filled, shellacked, and waxed it. erences

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HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY Drills Easier! If it’s Spaulding BAKELITE-DURESTO —and furthermore, you can depend upon Spauld- ing Bakelite - Duresto panels as combining in one material these vital qualities—drills without chipping; cuts clean, leaves no ragged edges; engraves easily; retains its natural mirror gloss, finish and color; will not sag or warp under weight of mounted instruments; possesses high dielectric properties. Ask your dealer for Spaulding Bake- lite-Duresto. Insist on it and be assured of these fundamentals of good construction and best results. Write for descriptive circular. Spaulding Fibre Company, Inc. Tonawanda, N. Y. SALES OFFICES—WAREHOUSES New York City Chicago Philadelphia Boston BAKELITE- © DURESTO Radio Cabinet Is First of New Simplified Blueprints UNIQUE addition is made to the Home Workshop series of blue- prints this month in No. 35, a simplified radio cabinet. This is a useful and at- tractive piece of furniture that can be made without difficulty by beginners in woodwork. It requires only a few of the more common hand tools, and the joinery neces- sary is of an ele- mentary kind; plain butt joints are used through- out. The blueprint is substantially the same as the illus- tration on page 85, but on a much larger scale. The details are full size, so that the outlines of the dec- orative overlays can be used directly as patterns. This saves considerable re-drawing and insures accurate conformity to the details as originally worked by George F. Kaercher. A complete bill of materials, or cutting list, is included on the blueprint. Another simple project is the book (Continued on page 121) Book trough and end table, Blueprint No. 3 Complete List of Blueprints NY one of the blueprints listed below can be obtained from POPULAR SCIENCE MONTHLY for 25 cents. The Editor will be glad to pro- vide, upon request, information rela- tive to tools, material, or equipment. Blueprint Service Dept. Popular Science Monthly 250 Fourth Avenue, New York GENTLEMEN: Send methe blueprint, or blueprints, I have underlined below, for which I inclose........ cents: No. Title Price i es ee ee 25¢ 2. Smoking Cabinet............... 25c 3. Book Trough End Table........ 25c 5. Ritcnen Cabinet... oo... scece 25c 6. Two-Stage Radio Receiving Set. .25c 8. Shaving Cabinet............... 25c¢ 9. Arbor with Gate and Seats...... 25c¢ Lee jee ae 25c 11. Bench and Tilt-Top Table...... 25c 12. Electric Washing Machine. .....25c Le eee eae 25c 14. Toy Train, Horse, and House... .25c 15. Home Workshop Bench......... 25c 16. Inlaid Radio Cabinet........... 25c 17. Cedar and Mahogany Chest..... 25c 18. Telephone Table and Stool...... 25c 19. Grandfather’s Clock............ 25c ee ee Se eee eee 25c 21. Colonial Writing Desk.......... 25c 22. Girl’s Cabinet and Desk........ 25c 23. Pergola Garage ............... 25c DA, GRMIERES TBIME: 6 5 veios ocececccus 25c 25. Sailing Outfit for Canoe......... 25c 26. Baby’s Crib and Play Pen....... Zc 27. Kitchen Cabinet Work Table... .25c 28. Pullman Play Table............ 25c 29. Toy Tea Cart, Garage, etc...... 25c 30. Tool Cabinet, Bench Hook, etc. .25c 31. Priscilla Sewing Cabinets........25c 32. Chinese Game Table............25c 33. Pullman Dining Alcove......... 25c 34. Trellises for House and Garden. .25c 35. Simplified Radio Cabinet ....... 25c Name... This $22 VICTOR Pure rier LOUC Speaker © $950 GUARAN. TEED to re. ceive Clearly any broad- 1 your set_brings jn, Sent PRE. PAID to you direct from S nufacturer, Li Promptly and taetved a — cost. Scientific construction and guaranteed performance of the VICTOR SPEAKER plus this extraordinary low price makes it unquestionably one of the greatest loud speaker values on the radio market. Its unusual vol- ume and clarity of tone insures you the height of radio enjoyment, The VICTOR SPEAK. ER is backed by an ab- solute factory guarantee Dominating Features In the VICTOR Speaker 1, Our fiber horn has a crystalline finish, coupled with an adjustable loud-speaking unit that permits wide range and clear resonant tone quality without distortion. 2. Metal parts are of heavy cast aluminum, brilliantly polished. Base is of cast iron, producing an even balance to the whole horn. 4 year’s guarantee from purchasing date against mechanical defect. 5. There is no necessity for auxiliary batteries of any kind. Just plug right in on the second stage. VICTOR SALES CO. 210 Bigelow St., Newark, N. J. GENTLEMEN :— Send me one VICTOR speaker on ten days’ trial. subject to conditions you advertise. I shall pay post- man $9.50 upon delivery. "spacapetteg Fo 2 REAR IES Have a Business of Your Uwn Get into the Automobile Business,—the world’s Greatest Industry. Start a business in your own town. Thousands of opportu- nities for Trained Men, Fifteen Million Autos, Trucks and Tractors to repair; fifteen million Bat- teries to keep in service; seventy million Tires to re- pair and replace. Thousands of our Graduates Earn $2000 to $10,000 Yearly Fit yourself for a better job at bigger pay. Auto factories and service stations continually asking for our graduates. Big Auto Factories endorse our school. Detroit, the “Heart of the Auto Industry” is the logical place to learn the business. Get the facts. Be a winner! Have a Business of your own. Write today for illustrated catalog. MICHIGAN STATE AUTOMOBILE SCHOOL 590 Auto Bidg., Detroit (The Auto Center) LOS Ll lelUcrl Photography atHome_' plan qualifies you quickly in spare sed at home for this great, Mscinsting feesion. Camera men earn $100 t vious €s° \ $250 a week and more. No = " 4 MOTION E ) A 1 Sense PICTURE CAM ERA Handsome Motion Picture Camera given free if you act . Takes real motion pictures on standard professions! film used all theatres. Earn monev on side. E Send for Illustrated Book—FREE Write today for handsome, ill d book exp , ee 4 tunities in Motion Picture Photography, also Com aEE Motion Portraiture. News Photography, with details of F Picture or View Camera. ‘Addeess: New Vorknsitat of Photography =z iit

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‘OR ker )S0 ARAN. D to Te- | Clearly broad. on your rings in, it PRE. ) to you ct from ifacturer, Pped ‘d at our tion and ance of ZAKER, ary low stionably st loud he radio isual vol- of tone > height lent, SPEAK. y an ab- Uarantee BS ker 1, coupled it permits y without Juminum, n balance ing date tteries of stage. ays’ trial, pay post- f opportu- on Autos, illion Bat- Pires to re- uates Yearly to factories graduates. etroit, the ace to learn gy SE HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY a —— substitute for Vacuum Bottle Made for a Few Cents HE picnicker and tourist can con- T struct with little difficulty a homely put serviceable container for keeping \Jiquids hot or cold. | Obtain a 1-gal. pail with tight-fitting | jid and a heavy glass bottle short enough to fit into the pail with an inch to spare, ‘and about 2 in. less in diameter than ‘the pail. Such a bottle will hold from '1% to 2 qts. A supply of heavy corru- | gated cardboard, a circle of plain card- board, a cork and some hard sealing- wax — wax that scarcely is affected by very hot water —also are needed. Cut from the cor- rugated board five disks just large enough to fit into Corrugated paper the bottom of the os ae pail. Wrap another strip until five turns have been made ‘about the bottle itself, and then slip bottle and tightly wrapped covering into ‘the pail. Cover this with a disk of plain ‘cardboard in which a hole has been cut ‘for the bottle neck. Then seal with | about 14 in. of wax. If suitable wax is hard to obtain, mold a cover of cork dust to fit over the top of the bottle. The dust is mixed with glue diluted one half and allowed to dry. When the can cover has been put on, the insulation is exceptionally complete for a homemade affair and this bottle can be handled quite roughly.—D. R. V. H. Stop for Bench Drawer | (\FTEN abench drawer is | pulled out too far , > /and the contents | |are upset. This! « ‘cannot happen if ia simple bench drawer stop is pro- vided, as_ illus- | trated. To install or remove the drawer, | the clip is pressed down.—A. L. SPRING CLIP Radio Cabinet Blueprint (Continued from page 120) | trough and table illustrated, of which the | builder, H. Caldwell, of Toronto, Ont., | writes: | “The first article I have made with the \aid of PoPULAR SCIENCE MONTHLY’S | blueprints is shown herewith, and I am | very proud of it, as, for one not ac- customed to it, it is very gratifying to observe the work of one’s hands. “This production is the end table, blueprint No. 3, and I made it of oak | ata cost of $3.50 for the material. It was very simple to make and the blueprint easy to follow, but it was some contract to jig out the ends. “I finished it by sandpapering well, uming with ammonia and giving two coats of shellac, which I rubbed down with felt and pumice. This gave a fine satin finish, which makes this end table a ‘classy’ piece of furniture, and well worth my effort. I am so tickled that I am going to try my luck at one of the [other articles on the list.” BLACK & DECKER QUARTER-INCH PORTABLE ELECTRIC DRILL “With the Pistol Grip and Trigger Switch”’ Bench Drill- ing Stand. The drill can be in- serted or de tached quickly by means of handle clamp. $12, In Canada $16 Free to Owners ot Black & Decker ve Quarter-Inch Drills | A grinding outfit (as illustrated above) for the Black & Decker Quarter-Inch Drill, price $3.00, will be given free to the first 100 owners of Black & Decker Quarter-Inch Drills, who will write and give us information on the follow- ing three points: 1 The serial number of your Black & Decker Drill, which is shown on the name plate. 2 The name of the store from which you purchased it. 3 Not less than 25 words and not more than 50 was telling us for what work you find it most useful. In order to receive one of the above stands free your letter must be written in ink or on a typewriter, on one side of a sheet of paper, with your name and address clearly shown, and must reach us at the address shown below not later than October 31, 1924. We will not wait, however, to send you the grinding outfit, but will send one of these grinding outfits free to each of the first 100 who reply to this advertisement just as soon as their reply is received. IS) Address Contest Department eae} i ee a Orders and inquiries may be mailed to 5 WHe BLACK & DECKER MFG.CO. ~ 700 Pennsylvania Avenue,. Towson, Maryland 121

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ab W-LDouglas © $5,°6,°7 « *8 SHOES 4 BOYS AT $4.50 & $5.00 Women of fashion should know that our women’s shoes are high-class, made in the most distinctive, up-to-date and exclusive styles, which appeal to those who desire stylish, comfortable and serviceable shoes at reasonable prices. le fr” MiG: le —vy { » (Qi (oh > - = iI\| WARD a] New = = ss [— ~7/ ; New Fall Style FF We: $ pag Broad Toe Women oH or M rat wei Colt. Centre Strap W L.DOUGLAS PEGGING - In Black Pee att Pump,with ElasticGore. $6.00 SHOES AT 7 YEARS OFAGE alsolight Russia Calf, $7.00 WEAR W. L. DOUGLAS SHOES AND SAVE MONEY FOR 38 YEARS, W. L. Douglas’ name and portrait have stood for quality, for economy end for satisfactory service. W. L. Douglas shoes are exceptionally good values. Only by wearing them can you appreciate their superior qualities. The exclusive, smart models, designed especially for young men and women, are leaders everywhere. W.L. DOUGLAS $7.00 SHOES are remarkably good value. Seldom have you had the opportunity to buy such high-grade shoes at this popular price. Shoes of equal quality, comfort and service are rarely found in other makes at our prices. WHEREVER YOU LIVE, demand W.L. Douglasshoes. They are sold in 120o0f our storesin the principal cities and by over 5,000 shoe dealers. For economy and dependable value, wear shoes that have W.L. Douglas’ name and the retail price stamped on the soles. The stamped price guarantees the value. If not for sale in your vicinity, write for catalog. a W.L. Douglas Shoe Company, 124 Spark St., Brockton, Mass. =) from the Inside ! AKE and keep vour cellar cry by filling cracks and coating concrete or brick walls and floor with Smooth-On No. 7. Excellent also for waterproofing garage, stable and wash-room floors, boiler pits, cisterns, septic tanks, water troughs, foun- tains, duck ponds, swimming pools, manure pits, etc. Requires about 25 lbs. of Smooth-On No. 7 for each 100 sq. ft. of surface and you can do the work yourself. Smooth-On No. 7 is the only practical waterproofing material that can be effectively applied from inside and to wet or dry surface. Can also be laid in a thicker layer Over worn wooden floor for concrete effect and watertight surface that is easily washed and kept free from odors, Sold in 5 and 10-lb. cans and 25, 50 and 100-lb. kegs. Write for Prices and FREE BOOKLET SMOOTH - ON MFG, CO. Dept. 60 574 Communipaw Ave. JERSEY CITY, N. J. yt poet WET CELLARS MADE DRY = _ CUNNINGHAM TECTOR-ame R SToR-a el ST * RADIO THE STANDARD TUBE FOR ALL MAKES OF RADIO RECEIVING SETS Back-country isolation melts into world con- tact as you tune-in on music, drama, and the final battles of the presidential campaign. Cunningham tube, type C-299, used with your radio set, trebles vacation pleasures. Cunningham Radio Tubes C-299, C-11, C-12 Dry Battery Types $4.00 C-301A, C-300 Storage Battery Types $4.00 Patent Notice: Cunningham tubes are covered dy patents dated 2-18-08, 2-18-12, 12-30-15, 10-23-17, 10-23-17, and others tssued and pending. Licensed only for amateur experimental and entertainment use in radio communication. Any other use will be an infringement. Cunningham 40-page Data Book fully explaining care and operation of Radio Tubes now available e by sending 10c in Stamps to San Francisco Office. po fn E OFFICE SAN FRANCISCO CHICAGO NEW YORK HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY Wall Ironing-Board Folds into Small Cupboard bere difficulty of building an ironing- board to fit into the wall lies in the construction of the leg. Some types have a hinged leg that extends straight down when in_ use. Others have a leg that is long enough to be placed at a slant, but this has had to be detachable to permit folding it into the wall. A STRAP IRON The leg is hinged with two iron links The illustrations show the method I devised to allow the use of a long leg placed at an angle. The ad- vantage is that garments may te slipped over the end of the ironing- board, yet the board and leg fold together into the closet. The leg extends from one end of the board down to the intersection of the floor and wall. It it fastened to the board by means of two strap irons, as in- dicated. A long hook in the inner wall of the closet keeps the ironing-board from dropping out unexpectedly when the door is opened.—J. G. BYBERG, Silverton, Ore. Cabinet Type Bench (Continued from page 87) piece mortised at right angles into the lowered end of the outer jaw passes through a slot in the baseboard of the bench. This piece slides in and out, as necessary, and is held in position by a pin that is placed in any one of the several holes, according to the width the jaws are to be opened. To preserve the new wood, rub it with raw linseed oil and when dry follow with a coat of shellac. You will find such a bench will become more valuable to you every day. Your tools are free from dust and close at hand. Expense has been kept to a minimum, and the parts of the washstand not used can be saved to develop other ideas in the home workshop. Carpenters usually prefer to place a vise of the type described by Mr. Tribute at an angle, so that the outside jaw, or at least, the right-hand edge of the jaw, slants downward from right to left. The lower guide piece then has to be far- ther toward the left. Such an arrange- ment gives considerably more “‘grip’’ to the jaws where it is most needed, that is, to the right of the vise screw. This is important because one’s work frequently is so large that only the right-hand side ef the vise can be used, |

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ng- the ave the 3Ses the ae pin oral are ith vith yme our nd. and 1 be yme ea ute , or aw, [he ‘ar- ge- ’ to hat ew. ork the ed, HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY 123 Photographic Vignetting Masks Made of Cut Film By Edward H. Flaharty ITH the use of cut film, vignet- ting masks may be made to pro- duce the effect: of diffused edges or fade- outs on photographic prints (Fig. 1), as though an air-brush were used on the negative before making the print. This new method does away with air-brush york or the slow and uncertain method of exposing through a mask a few inches from the print- ing frame. Rr , : A piece of j process cut film (process film is of extreme con- trast) is placed in a printing frame with the emulsion, side out, Over the printing frame (and aé_e few inches away from it) is placed a card- board box or other mask in which a hole has been cut, either round or oval, and about one-third smaller than the diffused area desired. A short exposure is made by a dim electric light a few inchesfrom theframe. The distance will determine the amount of diffusion. When the film is developed, it will be found that a large diffused black area ap- pears in the center (Fig. 2). When this piece of film has been dried, it is placed in aprinting frame. Behind it another piece of flm is placed and a second exposure made. The center of the second film is transparent and the outside black (Fig. 3). In making prints from the portrait neg- ative, this second piece of film is placed in ‘front of the picture film and the paper. |The result will be that the portion of | paper in back of the opaque edge of the mask is not exposed and the resulting | print shows the edges of the picture fading | out into the white space around it. A set of these celluloid masks may be made of many _ | eee Fig. 1. Portrait made with mask |, eaanl Fig. 2. The first or Peliminary film different sizes and ‘Shapes and used to | Meet various needs. These masks may be used in grouping several prints on one piece of paper, as is often done in arranging different poses of children on one strip of paper for framing. | Similar masks to those described above could be made by the same method for bust portraits where it is desired to have only the bottom half of the picture fade out into white or black. Fig. 3. The second or maski film FISEMANN ELE ¢ T R..1C Ack. EQUIPMENT The outstanding characteristics of this new Receiver are extreme selectivity, extraordinary distance range and exceptional clarity. Tuning is very simple. The 6-D is a non-oscillating Receiver, and no potentio- meter or stabilizer is employed. Step into a radio store and examine this new Receiver. Ask for a demonstration, and see for yourself its many superior qualities. SPECIFICATIONS Circuit: Two stages of tuned radio frequency amplification, detector and two stages of audio frequency ampli- fication. Tubes: Five in all. Jacks provided for either five or four tube operation. Batteries: Either storage or dry-cells. Cables: Complete set supplied for “A” and ‘‘B”’ batteries. Wave lengths: 200 to 600 metets, with uniform efficiency of reception. Aerial: 75 to 125 feet, single wire. Panel: Aluminum, with attractive crystal black finish. A perfect body capacity shield. Dials: Sunken design. Shaped to fit the hand and permit a natural position in tuning. Rheostats: Adequate resistance for all standard base commercial tubes. Condensers: Single bearing, low leak- age losses. Sockets: Suspended on cushion springs which absorb vibrations. Cabinet: Mahogany, with distinctive lines and high finish. Ample space pro- vided for ‘‘B’’ batteries. Price, Without Tubes and Batteries, $125.00 (1 For Sale by Reliable Dealers eAnnouncing the 6-D Receiver 5 tren 6-D embodies the most modern developments in radio engineering, together with unusual design and workmanship. It meets the most exacting re- quirements of discriminating buyers. EISEMANN -MAGNETO :CORPORATIO General Offices: 1065 Broadway, New York DETROIT ° SAN FRAN CISCO cCHICAGSG

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—— Workshop] hemistry Simple Formul, Will Save Tig. and Money Hew putty can be made has been mentioned before, but the removal | of hardened putty from cracks and erey. | ices is another story. At times it is i ceptionally difficult, or almost impossible. | To loosen putty under such conditions dissolve lye (sodium hydroxide) in a litt water in a glass vessel and add, for each two tablespoons of lye, one teaspoon of hard soap cut in shavings. Dissolve the mixture with slight heat. When cold it should have a gelatinous consistency; jf this is not the case, add a little more soap, | Apply this mixture to the putty quite thickly and leave for a day or two, and the putty will be softened so that it can be removed easily. Knives that have loosened from their handles can beresetfirm- ly. Ina por- celain or iron dish melt two

Using a plaster - of- Paris ce- ment to re- paix @ broken or- nament (above) and _reset- ting knife in handle (at the right)

teaspoons of rosin and add, while stirring, one teaspoon of precipitated chalk. Pour the molten mass into the handle. If the handle is thin and narrow, merely mix the two substances intimately to gether after they have been powdered, and force as much as possible of this powder into the handle. Then take the knife and, wrapping the blade in a wet cloth to keep it cool, heat the haft over an alcohol or bunsen flame. When it has attained a red heat, insert the handle into the powdered mass. The hot shank. will melt the mass, which when cold will hold the knife firmly in the handle. Uniting broken pieces of marble, plaster-of-Paris figures, alabaster and ob- jects made from composition ivory is not difficult provided the broken pieces are not too heavy and are not subjected to much wear. To make a cement for this purpose, take four tablespoons of plaster of Paris and mix with one tablespoon of powdered gum arabic. When it is to be used, add a little cold water until a thick paste results on mixing. Apply this paste within five minutes of preparing, as it sets and hardens quite rapidly. This is valu- | able for reuniting objects of sentimental | value, which are not used every day. Repairing broken glass, porcelain, and (Continued on page 126)

r f I —rnre — ae ee.

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shop ry j las thet ¢ Time Money | ae | iS been emoval | id crey. | t is ex. | Ossible, | ditions, | a little | ‘or each Poon of | Ive the cold it ney; if | re soap. | Y quite wo, and t can be m. their lles can set firm- In a por- ain or n dish lt two stirring, k. Pour idle. If merely ately to- »wdered, of this take the in a wet aft over en it has ndle into 1ank. will will hold marble, - and ob- ry is not ieces are jected to t for this of plaster sspoon of t is to be i] a thick this paste _as it sets s is valu- ntimental | day. Jain, and } a Your POPULAR SCIENCE MONTHLY Int O THIS one brilliant book of 280 pages have been condensed the outstanding facts that scientists have discovered since Aristotle, the father of science, dissected a frog to see what made its heart beat. How often have you wanted to know about the won- derful discoveries in science that have so changed the world we live in... the secret of radium... the romance of the atom . .. the origin of the earth! Or you may have wanted to know why glass is trans- parent .. . how fireflies produce light . . . why the grass is green, ..if radio waves move in a straight line? All of these questions, and hundreds of others, have now been answered, for the first time, in one book— THE POCKET GUIDE TO SCIENCE. And you can get this wonderful book absolutely free! All that you probably will ever want to know about science is told in this one book that will fit in your pocket or grace a library table. The curiosity-satisfying facts about the world we live in are made instantly available to you in simple question-and-answer form in THE POCKET GUIDE TO SCIENCE, ame in Gold ~on this Wonderful Book. 0 are assured of the accuracy of the answers in THE Pocket GuipE To SciENCE because it has been edited by Dr. E. E. Free, the distinguished author of “‘The Story of Man and His World.” Dr. Free has a re- markable genius for condensing the known facts about scientific questions into vivid, easily remembered paragraphs. FREE THE POCKET GUIDE TO SCIENCE is not for sale. It is offered to you absolutely free with a 14 months’ subscription to POPULAR SCIENCE MONTHLY. In THe Pocket GuipE To SciENcE you get full information of all that the scientists have discovered up to the summer of 1924. Poputar Sctence Montuty “carries on” where THE Pocket GuIDE TO SCIENCE leaves off. The Pocker Guipe gives you all the information up to right now— Poputar Sctexce Monruty will give you all the im- portant, interesting and new discoveries of science for the next 14 months. In every issue of Poputar SciENCE ONTHLY area dozen or more important arti- és that explain and picture the most fascinat- ing and significant new developments, dis- coveries, and undertakings in exploration, ch PopuLAR SCIENCE MONTHLY, 250 Fourth Ave., New York in engineering, in health, in electricity, in medicine, and in every branch of science. And there are also, in every issue, a hun- dred or more articles describing the impor- tant new inventions in every branch of A Few of the Hundreds of Questions Answered in the POCKET GUIDE TO SCIENCE Why does static interfere with radio messages? What gland makes people grow tall or keeps them short? Why do we grow old? What is the safest stimulant? What is the function of the liver? y are tears salt? Can energy be destroyed? Why can’t you skate on glass if it is smoother than ice? How do self-winding clocks work? Why does an iron ship float? Can we see atoms with a microscope? What are electrons? Ts electricity a form of matter? What is a crystal? How large is the universe? Why do the stars twinkle? How do we know what the stars are made of? Is the inside of the earth molten? What is an electric spark? What makes the noise of thunder? mechanical activity—page after page filled with photographs and descriptions that show you how you can save money in the shop, around your car, in your store, office and home. But all this is only part of the contents of one issue of the amazing Poputar SCIENCE Montu_y. It takes over 300 articles and pictures every month to tell the readers of Poputar Science Monrtuty all that has happened in the scientific, radio, mechanical, and automotive fields. Your Name in Gold We will stamp your name in 22-carat gold on the cover of THe Pocket GuIDE To SclENCE at no extra cost to you if you use the coupon below immediately. You are offered a 14 months’ subscription to Popuar Science MonrTu-y, regular price if bought by the month would be $3.50, with Tue Pocket Guipe To Science free—all for $2.95, plus the few cents’ postage. If you are already a subscriber to Poputar SCIENCE MontHu ty we will be glad to extend your sub- scription 14 months if you accept this offer. In using the coupon please PRINT your name SEND Send no money, just the coupon. If within 10 days after you receive the book and magazine you decide that you are not satis- QO fied in every particular you may return them and your entire payment will be re- ONEY funded promptly and without question. Address Could any offer be fairer? —— Name POPULAR SCIENCE MONTHLY 250 Fourth Avenue, New York I accept your offer of THe Pocket GumpE To SCIENCE and a 14 months’ subscription to Poputar Science Monrtaty. I will pay the postman $2.95, plus the few cents’ postage when he delivers the Pocket Guiwe and the first issue of PopULAR ScreNcE MonrTHLY. If the book and magazine are not fully satisfactory to me I will return them within 10 days and you are to promptly refund my full payment. Please stamp my name in gold. City P. S, 10-24

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‘4 » THIS NERVE MEANS HEALTH ara HAPPINESS PINCHED NERVE MEANS SICKNESS axzd DISEAS!I ne neé es, t] interfering v Une , . } flow = \ \ ~& & a a \ g : 1, _" 4 A O\ > ; l NKER HALF OF WOOD BLOC? MOL E Details of the wire gang and the sinker, which is cast in a wooden mold two blocks of wood. An eye let of heavy 2 copper wire is inserted in the mold before the melted lead is poured. f +} wir Ol Ue Bend the ends inserting, so r the eyelet. peiore 1 good hold f f e outward as Oo lnsure : About 10 ft. of line is used to connect the sinker with one branch of the gang. The — is connected with 15 or 20 ft of line to the other branch, while the mai: lir gue es boat is fastened to the remain- va portion. This gang allows the lead to sink the troll, but keeps it 10 ft. away from the bottom and consequently lessens the likelihood of entanglement at. all times. When the lead is felt touching bottom, take 1n a few feet of line or speed up the boat a little and the troll will be kept spinning along in just the right place. STANLEY W. BLANCHARD, Grand Mere, Quebec, Can. sé Home W iiilioaie Chemistry (Continued from page 124 the like can It is possible fully that the but se ries be done with various cements. to mend the fracture so skil- joint hardly can be noticed, if ever, will the repaired irticle be safe to use. If mended with alum, isinglass, gelatine, any other substance that is either soluble or softened by water, the repaired article will loosen at the point of union and break at the slight- est pressure, especially if placed in hot water. White lead thinned with boiled linseed “ to a very heavy paste so that it can hardly be spread with a knife will mend china and porclain, but its disadvantage : is the long time required for it to dry, three or four months being necessary. White of egg mixed with a small quantity of plaster of Paris is also good, but it re- quires careful handling, even after uniting the break. But above all, remember that water is injurious to this cement.

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Serviceable Bar Compass Made from Brass Curtain Rod BAR compass or a pair of trammels frequently required in laying out circular work in the home workshop can be made easily and cheaply from an old brass curtain rod and a metal pencil clip, as shown below. A hole the size of a tenpenny wire finish- ing nail is drilled in the end of the inner INSIDE PART OF of | CURTAIN \ i ~ . : J i . PIECE OF OUTSIDE 7 PART OF CURTAIN ROD Drawing an arc of long radius with sim- ple homemade bar compass or trammel rod. The nail is ground to a sharp point and fastened in the hole with a drop of solder. A 3-in. length of the other rod is used as the sliding part of the compass. To it the pencil clip is soldered. S. Root, Fall River, Mass. How to Build and Cover an Upholstered Footstool (Continued from page 86 and driving in only a few large tacks. This is called ‘‘slip-tacking’’ and is shown in Fig. 6. Draw the muslin over the top of the stuffing and slip-tack the other side. Repeat the the ends. A stuffing regulator, which is a piece of wire shaped as shown, is used as in Fig. 5 to scratch the stuffing under the muslin, should it appear uneven. Care and patience should be used drawing this muslin tight to form a smooth top. process at A piece of sheet wadding usually is placed over the muslin. This is cut to fit the legs, but is not tacked. The final covering is put on in much the same manner as described for the muslin (Fig. 6). Genuine leather, imita- tion leather, tapestry, and cretonne, all make excellent covers. It is well to choose some material that will match other pieces of furniture in the room. Much around the legs. Always cut out a small square in each corner first and gradually fit to the legs as the covering is stretched |on. Stretch the final covering very | tightly and slip-tack as in Fig. 6. Use 4-oz. tacks for finishing and keep them close to the edges so that will be hidden by the gimp. You may buy gimp to match your covering or you may make it from 1-in.- wide strips of the same material as your cover and turn both edges under so that they will held in place when the upholsterer’s tacks or nails are driven. If Design No. 2 been chosen, gimp is necessary, but especial care be taken to turn the covering that a smooth finished edge will fit closely against the legs and along the edge, where it is nailed as shown in Fig. 9. Small metal glides driven into the bot- tom of each leg add much to the service- ableness of the stools and prevent the marring of polished floors. they be has no must care should be taken in cutting | under so | ‘Coast to Coast HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY reception verified hy Miraco Users NO »s E Beca Miraco ey New York Hears London and California! Have reached i lar LO, London, Eng] KGO, Oakland. (¢ : | Miraco is the best set I 1 ed ( \ H \ bank \ N. ¥ The fi pick p was Cuba. The M finest I ha I ri r i! ] } Will t 1 order ' | c, Holt, Mich, Texas Hears Porto Rico! I hav 125 ’ my log t late [ o M San |] ] ge S vi San J Por R Cliff G Texa . Illinois Hears N. Y. and California! Our Mirac M reat and | bel ird U.S \ ( We New Y k Ca kK Pt yhet, P Ohio Hears Oregon! Mit f J urd At! \ Cit yo Seete port I pa, Fla., I t W D and Portland, O I ti range t it Pe Rov NM \ 1 O Oklahoma Hears a- Plenty! Am Q + c M to every I H ce ed 1 t than | with any fitt or an oe ( e, Okla. Minnesota Hears Texas! I ng Mir od get recept n fror « to 4 i in mM ( ( mn id + HI + Dalla Tex . I quist, 4 ksto, M A West Virginia Hears California! I iv my Mirac 1 \ SOstations, inel ng WFAA WBAP, WGAM and best of all—KGO, Oakla ( | H. Davi \\ . town, W. \ 0 h ft you can't get a program with the J\IRACO [ you need not try any other set . AM ge tting all over the United States with mine, says J. C. Brown of Albertville, Ala **T heard New York and California the first night on my rhage "Mee advises F red Knappe nberg, Jr., Burns, Colo. ‘“Never operated a set before. Heard Pittsburgh, Cleveland, Chicago, Cuin- cinnati and others the tried Miraco, writes L. F. Car ascoag, R. |. In the improved Miraco, thrill getting vast distances obtainable only costing up to three or four times as first time | my penter, Fr thousands find same gener ill, ibor ite sets much. As “The stations No blurring sound 1S as with expensive, el easy to operate as a phonograph! all come in so clear and distinct. The ] . ° } and whistling. production ol plain as is that of a a cabana only much more satisfying,’ says C. H. Eacker, McCarroll, Ill. Send ‘coupon now—learn fully about radio's finest low-priced receivers. DEALERS -JOBBERS Write for our new proposition! AGENTS “GETS *. COAST TO COAST” Tested and Approved = by Highest Authorities ty) THE MIDWEST 808 Main Street, RADIO CORPORATION Cincinnati, Ohio \,

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HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY w New York Fe What do you expect from Radio i Selectivity? But have you thought of tone and simple oper ation? Itis there that Federal’s quarter- century experience in the manufacture of electrical communication devices gives the Federal set such outstand- ing advantages. You must operate a Federal—you must hear the full, rich beauty of Federal Tone — to know what these advantages mean to you. TELEPHONE ia Chicago FEDERAL & TELEGRAPH CO. Buffalo, i; X. veral Sanat ADI OPre aia Pittsburgh ancisco Can ada urg, Wr of Free Trial; Easy Payments G t mar GIBSON 1005 Parsons St Pisani: Mich. | sTRINGED INSTRUMENTS Lin s Leading Manufacturers WD ira ee natruments ws | | Small Motors, Transformers and Electromagnets Design and construction data for small , small, low peer high-tension tran rmers, electromagnets and induction coils le how to rewind used motors for chang in voltage, speed 1 frequency Price postpaid, $2.50 Popular Science Monthly New York, N. Y. aD Using ‘i Truss 250 Fourth Avenue, STUART’S PLAPAO- FADS I self-adhesiv. No straps, nicl oe or spring attached s cannot Reduced Reduced Fac-Simile : aa Fac-Simile Gold Medal : es pe ae Grand Prix velvet easy to appl; inexpensive. \ rded Gol het dab PREE Magat Coss 790 Stuart Bldg., St. Louis, Mo. Sunlight Used in Stenciling Designs on Woodwork By Ernest Bade, Ph.D. FOODWORK made W workshop, such as frames, book ends, smoking the like, stenciled by means of sunlight. The process is simplicity itself, but re- quires considerable time. All that is done is to cover the panel or piece to be decor- in the home trays, picture ‘abinets, and Stencil ready for exposure ted either one of the commercial that be obtained in great at any paint store, or a homemade witn a stencils can Variety can be ornamented with designs | stencil, and expose it to the sun for two or | t This results in a rich brown , varying in depth according to the time of exposure. It is much clearer hree weeks. design and irper on the edges than “4 ordinary stencil made with stain or pain The soft woods, that is, the a rive the best results. The stencil, which may be stencil board, cardboard, tin or wood, is attached to the freshly planed surface of the wood in such a way that it will not shift or curl. If it is of thin cardboard, cover the stencil with plate glass. When the desired shade or darkness has been obtained, the design is fixed by polishing or by coating the surface with Waxing the de sign at left is best first to oil the wax. It surface with a mixture of boiled linseed oi! varnish or Use just a little and rub the wood. When dry, repeat the operation. The is used primarily to bring out the grain of the wood. Follow and turpentine. it into oil the second coat with one or more coats of furniture and wax, thoroughly polish with a clean rag. Mending an Umbrella i ROKEN joints between the braces and ribs of an umbrella can be re- paired with friction tape. Simply put the end of the brace where it belongs and wind tightly with the tape in sucl the of the joint will unduly. The umbrella opened and closed without be f¢ 1a way action not be with be and the rfered then can difficulty inte repair will yund to gly well.—W. 5S. last surprisit

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HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY Simple Tools Form Raked and Rodded Brick Joints EVEREADY MORTAR FLASH LIGHTS remover for iy BATTERIES recessing brick last longer joints can be made from a 1 by 6 in. block of wood with a large wood screw turned into one edge. The head of the screw is left exposed the depth that the mortar groove is to be. When the mortar has set awhile, the tool is run along the joints, cleaning out the mortar neatly. A set of ordinary S , wrenches provides excellent burnishers | “4 Pa for the grooves. Different sizes will fit e : joints of different widths.—FRED W. PAGE, Winfield, Kan. Cement Repairs Split Water- Pipe in Emergency For safety’s sake—ase you flashlig hi! OW Portland cement was used to | repair a cracked water-pipe is shown | in the accompanying illustration. The pipe, which was split by freezing for about 4 in., was located in a rather awk- ward place, so that the cement trick saved much time and expense. The water was shut off the line and a piece of sheet iron bent around the pipe to make a retainer about 21 larger in — than the pipe. The How cement saved evlinder was tied an awkward water- : pipe replacement with wire and the ends were stopped with two pieces of thin board. An opening was left at the top to pour in the cement, which was allowed to set for several | hous before the water was turned on. | The cement sealed the break and stood the pressure as well as the original pipe. | This will suggest other possible repairs to | valves, tanks, wooden tubs, vats, cisterns, well pumps, and the like.—H. W. Ne 950 ao EVEREAD Ho teeiie lire 5 s He . 1 e e Pails Have 7 , Sener caus Handles Riveted on Bottom ; FOR ruasmuients “TONAL carson CO." IRE pails filled sai with sand or water should be kept at convenient places around every shop or farm _ building. HE heavy, nauseating odor of gas. Reload your flashlights and ke Sand should be used Leak in the line somewhere. Use on the job wi I sh, strong | in pails that are your flashlight! Trace the deadly Unit Cells. And if you havent hung near electrical fumes to their source. Use your flash- light, see the nearest Ever machinery. lig rht! Meter-readers always do Use at O1 Fire pails may be vour Eveready wherever there is need Buy the 1 oved E I made at home by - for safe, brilliant, portable light. lichts from. electrical, i a nn } lers j « fastening a heavy yanpie RIVETED ON 1 é é g You can safely poke a lighted Ever- oe _ ij 1 , eady right into places where an open Ji 46 accessory shops. 65c¢ to $4.50, « to the ottom of an ordinary pail, as illus- tk poke ies = Eu oo an ecentnal saclay tua trated. This gives an excellent grip wher So, play safe. Use your flashlight age the contents are to be thrown on a fire and : , : . Use it on those dark cellar stairs. Use is as effective as the rounded bottom in : : it in that dark attic. Flood that dark NATIONAL CARBON COMPANY, preventing the use of the pails for other ; heillianc 7 ee . , ses than fire preventior closet with the brilliance of high noe New York c | Purposes thi prevention. Keep several Evereadys about the house Nat ( ‘ | The handle may be riveted on for use with sand and soldered for use with water. And keep them handy!

Page 130

HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY

Good “Turns” that Register When you're winding a coil for your radio, a Veeder Counter comes mighty handy for counting the turns of your winder. When you’re trying to step-up the production-rate of a newly de- “VEEDER™ or operations so for your guid- veloped machine, a counts output each gain registers ance. are : When you want to run a machine, a generator or other apparatus at x! ) certain speed, you get a count R. P. M. most conveni- trom COUNTER

i small Revolution Counter be- | gisters one for a revolution especia ly han ly for ~* inting the turns of a coil winder Also adapt to recording outp t (or operations) of many types t light machinery Mechanism _ will stand a very high rate of speed. If run backward the counter sub- Price (Cut 4-5 size.) Small Ro- tary Ratchet ter, to register reciprocating move- . also $2.00 tracts. $2.00.

Ir small machines, ¢ Speed Counter the handiest instrument lor hinding revol att r itions-per-minute of a You hold the tip the counter against end of revolving lightly when the second 1 of your watch comes to OQ; nute is up. A spring ording mechanism nywneel. haft; press release

Cut less than |, size \ ler Opec ‘ounter enabics Keep motors, engines, generators, line fting and machines operating at effici ient speeds. Price, with tw ips, (as illustrated) $3.50. FREE— The 80-page Veeder booklet of counters you’d like to see—or set working. The Veeder Mfg. Co., 44 Sargeant St. Hartford, Conn.

Heating Coil Operates This Simple Electric-Light Flasher AX’ ELECTRIC-LIGHT flasher that operates automatically on the prin- ciple of a thermostat is made as shown in the accompanying illustration. This type of flasher is in extensive use, to control a single lamp behind a transparent sign. The heating core is 250 turns of No. 38 insulated German silver wire. If this is not available, No. 38 s.s.e. copper wire will serve the purpose for experiments, but it heats excessively with constant use. HEATING-COIL ING SCREW BAR 31N ADJUST

Alternately heating and cooling, the coil moves the contact arm back and forth The flasher arm is insulated with thi asbestos paper before the coil is wound on. When a current is tu the heat- being in series with the lamp, re- ceives current and its resistance prevent the lamp from lighting above a dull red The heat from the coil causes the brass bar upon which it is wound to expand, and it pushes the other bar, until contact is made with the adjusting point. This short circuits the eating coil and causes the lamp to ugh ip to full brilliance. The heating coil the cools and this causes the bar to return to its original position, when the whole series is repeated.—THOMAS E. MILLER. rned on, ing coil, being cold, over Screw

-atherproof Corn Shocks Made with Simple Tying Tool HE tool illustrated for tying shocks has proved most efficient. By turning the handle like an auger, the rope is wound around the pin and the shoc! compressed evenly in all directions. This insures a weatherproof shock. The curved shield is made of a 114-ft. section of : wide wagon rim. A central hole is drilled through it to take a free working pin and two other holes are drilled to take a cor?

sharpened end of the pin is shoved into the corn shock and the rope, one end of which is fastened to the pin and passed through one of the holes in the shield, is carried or thrown around the shock and slipped through the other hole in the shield and the remaining hole in the pin. It is pulled tight and the handle is twisted to compress the shock.— HARRY FRYE, Tullahoma, Tenn. handle together the shock Twisting draws small rope. The pin, which is 21% ft. long, also has two holes of the rope size. n use, the’ | |

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HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY Send *1 Now! Graceful Music- Stand ‘Sade from Left-Over Pieces of Wood “HE ordinary metal folding music- stand used by violin and saxophone players and other instrumentalists always looks out of place in a well furnished living-room. Wooden stands of the com- mercial type are usually so cumbersome and heavy as to be equally out of place. When a more appropriate music-rack is desired, it is a simple matter for the ama- teur woodworker to make a light and graceful stand that will look well along- side any piano. The original of the stand illustrated was made of the finest mahogany, but any good cabinet wood will serve. It is used for sheet music only; for heavy music books the pedestal should be stouter, but the same method DOWELED JOINT:

\ 0 of construction o. and general pro- aj ai portions should be | I followed. d 1 Left-over pieces a t were used for the 7 material, the parts a! § f required being as Af) square pe. for stand by 1 by 1 i1 Re i-] led screws Make the stand of three pieces, using doweled joints. Glue only one end of eac} dowel, so that the stand can be taken apart. Then place the pieces together and plane them up straight and square, making the standards 1 in. square at the bottom and 5¢ in. at the top. Insert the small blocks at the joints and complete gluing the joints together. The feet may be cut out of pieces of the size given above, or, with less waste, out of one wide piece. Nickel-plated, brass, or other round-headed or oval screws are used to fasten the feet to frame. The bottom frame has a half-lap joint at the center and is glued together. It is then screwed to the feet with fine screws, or doweled and glued. The rack itself is made as shown in the detail. The bottom piece is made the shape indicated and screwed to the rack. The shaped block at the back also is screwed on the rack at top and bottom and is bored at the correct angle to receive the standard.—A. E. Thong Holds Watch § Securely oo SLIT FOR BELT I put on rough clothes for 2) yy \

camping, I use a leather thong for / my watch as a if‘) | ¢ safeguard against Vi) loss and breakage. << a. Belt lacing about FOR WATCH Stucy 1; in. wide and 10 in. long with slits cut as shown is entirely satisfactory.—L. W. H.

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Expert Toolmakers and Diemakers in Demand “Sipe a pt rywhere arching are S¢€ and are willing to pay em mone) The 1 ger of one of the largest ma t works in the world, in a letter i s y us h him secure the ser Vi S ( tec! y tra mechanics, wi —“There is not much difhculty in ‘ g re ent—but we must have B ( the trained 1 You can lly try Right at home, in Ss € Ss I spar time that now LQ to vas the Ir erna al Ce rrespon- S vols will te 1 all you need t ae & king, Diemaking, M Shop Pract iny other sub- } lich you are interested Mail the Coupon To-day for Free Booklet! INTERNATIONAL CORRESPONDENCE SCHOOLS Box 7619-D, Seranton, Penna, v c r obl my part, ple tell me I can qual r t t before v 1 I have r BUSINESS TRAINING SOUnSES a tion is it I i riA ) Cost A ng Spa 9 French TECHNICAL AND INDUSTRIAL COURSES (Electrical Engineerin [ : B Arch itects’ Blue J [ ti ¢ {js Ar tural D C) ne B t {J - >} ic QO Pha macy ‘2 O ng CO Ag i Poultry (js Engineering C) Radio CJ Ma atics Name Str 3 24 Ad City State Orr ation Per a residing in Canada should send this coupon to the nt 1 resp € Schools Canadian, Limited, . 7 — — i. mI os I \ ~~ \/ t \ = O78 ~d) “UN > . 7 ean Easy toDraw Cartoons When Shown in the RIGHT WAY > of the cl cartoonist nd co artists d how_to « in thei r spare time oo foll ing ‘artooniet Evans’ Simao and Easy to Learn Method re now MA \KING (¢ OOD MONEY Send one of and let Mr. Evans h 4 ty » Portfolio of Cartoons and full rse. It is not expensive. erest ir ir dra see if you na ve THE W. L EVANS SCHOOL OF CARTOONING Cleveland, Ohio 825 Leader Building Special Curtains Convert Canoe into Comfortable Shelter By Leroy W. Hutchins J HEN a canoe cruiser needs a water- proof shelter for stormy weather, fortunate if he has provided props and special curtains so that he can turn his canoe upside down and convert it into a small tent. To fit up a canoe in this way, fasten metal loops to the inner sides of the gun- he is wales, one on each side of the canoe, about one-third from the end. These hol the two prop poles, which may be any light wood about 5 ft. or more in length, and carried along, or new poles may be cut for the purpose at each camp. To fit the curtains, prop up the canoe and tack one edge gun- of the cloth to the g The canoe shelter set up and method of fastening brace poles and side curtains wale on one side; pull the cloth to the Q ae : ms art en ee ee | floor as desired, and tack it lightly. Wher shape of the side is satisfactory, cut just beyond the line of tack to a hem. When one side is made, Sia be used a pattern for the 4 cloth llauyr ¢ as Provide obtain patented to attach the curtains to the and either insert metal grommets along the lower edges for wn the canvas. Provide tapes rd end for tying them. Such a is quite roomy, 6 or 7 ft. 5 or more ft. high center and usually about 16 ft. Snaps or fasteners Canoe, tape loops . staking do at the forwa being at the shelte r * 4 wide, long Ordinary C-Clamp Lengthened furniture clamp for Cabinetmaking AN + may be constructed cheaply from an ADJUSTABLE ordinary iron C-clamp and a length of stiff band iron. Saw the clamp in two and drill two holes about 1 in. apart through the back of each half. Rivet or bolt the bar to the half that carries the thumb-screw. Drill one hole about 1 in. from the other end of the band iron. Fasten a_ stove bolt through this hole and through the hole nearest the end of the other half of the Ais ~ STOVE BOLTS Band iron used to lengthen clamp clamp. Using the other hole as a guide, drill the band iron; then move the clamp along one hole and repeat the operation. In this way a series of correctly spaced holes will be made, giving a wide range of adjustment between the ends of the clamp. The uses to which the furniture clamp is put will determine the length of the band iron.—RICHARD C. TARR. HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY FE demand ormous right now for McCarrie-trained Dental Labor EXVERTS at $ $15 0 a week! Only prof i ed—only kind of profess ional work that y« u cal im er inafew months! 70,000 Dentists Need Laboratories At Chicago ne I Ires Dent al Labor Bk n tl W Sd. Pe ndivid tion, Piseasill by doing pel Dental Laboratory jobs. I prepar f — iver $3 No classe xt-bo $50. 00 Outht FREE! If you write at once! For oe, aes ee every studer n DP 0 f tool materials and wets 3. Writ efor free offer today. Open a Laboratory of your own. Littl ipit al needed I you are Me rie ai i, My “it structi includes Lal ra- manager 1 $15,000 a r profits mad easily by Dental Laboratories, 1 Wil Make You a FREER.R. Fare $2.75 f0iecg inset Dental GET MY OFFER QUICK! Big, New Book FREE! Pells you all about the ties waiting for Laboratory Exper.in4to6 Menths urprisir ag opie rtun.- ers o sme persone 50 ayl H. A. McCARRIE, Director McCarrie School of Mechanical Dentistry | | | emia ' Vept. 902-J, 1338S. Michigan Ave., Chicago || oxmke4oO-aeTRar, a4 Pay in easy monthly paymentsand getaStudebaker, the lifetime watch, direct from the factory at low- est factory prices. ‘21 Je wels, 8 adjustments including heat, cold, isochronism and 6 positions, 5 Write for po bw Bok WRITE showing 64 newest, thin-model «. - : designs. Sent FREE! pane poveere io . s ffer. sainazing Studebaker Chain FREE $7201), Ofer. FREE Sook of Ad- lasts. Get pbesntital Style Book in vance Watch Styles colors FRE and $1 down offer. STUDEBAKER WATCH CO., Dept. W23 SouthBend,Ind’ | Canadian Address: W indsor, Ontario NOW! New Low Engine Prices Only $F)69 amonth forafew months —easy toownthefamous standard WITTE En- gine. Uses Kerosene, Gasoline, Distillate or Gas. Equipped with celebrated Troubleproof WICO Magneto. Simplest and cheapest to op- erate. New device makes starting easy. 60% surplus s 2to25 P—all 1 FREE BIG NEW ae ahaa tenen Gusher to ban se ENGINE BOOK NINETY DAYS’ FREE TRIAL. Write today for my new illustrated engine book—sent absolutely Free. No obligation to you. WITTE ENGINE WORKS 2222 Witte Building, KANSAS CITY, MO. 2222 Empire Building. PITTSBURG, PA. a ON °* Big ba: poring, easy payments on late ple Ry os derwoods, oyals, L.C. Smiths ‘Remieetoon. ete —per- fect machines expe rtly emanu~ factured by the** Y oun: Process’? guaranteed like new for five years. Shipped direct de doe our factory to you » ig sav Our big iitustrated catalog FAY sent free and without —” to buy. Write for yours to ‘ Young Typewriter Co. Dept. 142A b 654 W. Randolph St., Chicago, It.

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Homemade Loop-Former Insures Neat Radio Connections NE of the greatest aids to radio fans is a loop former for bending neat and uniform loops in the bus bar com- monly used for connections. Various types of commercial benders are avail able, but I have found that the home- made one illustrated serves excellently To make one like it, take any flat strip of iron you have on hand, say 1/16 in. thick, °, in. wide, and about 5!4 in. long, and drill a hole in the center. In this rivet a a pin, or else make a large dent or impression. In = er case, the projection need be only a trifle higher than the bus bar or wire that is to be used. Next, drill as shown, a hole for the pilot, which should be about 5/32 NARROW STRIPS 7 SID ; N a9 See ee) J gs \ gy es) CUT OUT f Vl i| = GO 7: _ A L fa | t 2 / L R = I t ia » | 4 = € + || ) c rm hi cae How the bend and used to bus bar former is made loops and angles in in diameter for in. machine screws. To bend the loop-former, loops to fit No. 6/32 clamp it as indicated in a vise, after first placing it between two other narrow striy »s of iron one of which should have a clearance hole or cutout. To shape the grip or handle, bend out the ends at right angles and fasten with a rivet or bolt, or leave straight and pass a rod through the ends. The base plate is approximately 1/16 in. thick, 134 in. wide, and 3 in. long Near the edge and at the center, rivet a pilot to fit the pilot hole intheloop-former Alongside, rivet a guide pin or make a dent as in the case of the loop-fermer. Scribe marks on the base plate to facili- tate bending offsets at various angles. Also indicate by an arrow how far the bus bar must be inserted between the pin and pilot to form a perfect loop This can be ascertained by trial. Insert the bus bar between the pin and pilot on the base plate, press down firmly with the loop-former and turn to right. Give it another slight, quick turn before releasing it and you will have formed a perfect loop._—P. A. DASCHKE. SOLDERING paste may be carried and applied most conveniently when in a tube such as is used for tooth paste or shaving cream. An old tube can be used for this purpose if it is unfolded and the | end cut off. After it has been filled with | soldering paste, crimp the end tightly. HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY 133 An Amazing Advance in ands Tube $i Solid Mahogany Cabinet of unique and artistic design Sold u vith or or with- oul the Loud Speaker Combination ~ pda ace RITE TODAY for full particulars of this most exceptional offer M Sets embody the very latest improvements known to radi T} licensed under Pfanstiehl Patents Pendin t itilize \ efficient Pfanstiehl Non-Oscillating System. Thi iscove! f Carl Pf the big sensation of the 1924-25 radio st n. Th t that coupling, the big thing that every igner beer f A coupling cannot oscil late. It is posit I I I new sag f musicai quality. It yperator. Yet it is so easy t ine prove that the outfit you select is eve bai hew 1g we have said for it. If it doesn’t make good our claims, back it comes, and your deposit will be cheerfully re funded. But if it fulfills all yo ur expectations, you may pay for it in e monthly installments. You don’t risk a cent when ordering from us. You must be satisfied, or we don’t do > the business. Is it any wonder that the radio buvers tl! vantage of such an offer? If YOU in early, while prompt shipment can be made. Send for full pa age of radio supplies this season. Beautiful Solid Mahogany Cabinets Just compare the beautiful outfit pic- tured above with the usual radio box and The speaker cabinet appears as horn! part of the combination unit. by a master designer finest solid mahogany, hx ymes. of merchandising, set—plus easy terms for actually less money sets sell for on a cash basis. Complete Outfits if Desired In buying from Marshall, you have the ch« acc essories, or the You have choice of dry cell or stor- Unless you already own the accessories, you can buy them from us at less-than-market prices, with your set on easy Your outfit will come all ready to set up and operate within a few minutes,—saving of aset complete with all set alone. L age battery outfits. terms. time and trouble—and saving money, too. bia Bd Wy My ™% This Beautiful Marshall 4Tube Non-Oscillating Receiver Complete with all accessories Easy Monthly Payments_2 Weeks Free Trial That is y remarkable offer we are prepared to make to you! Designed = an fashioned of the te it will harmon- — curpri ize with the furnishings of the finest Yet through our different way this exceptional cabinet value— plus the unequalled mechanical qualities of the Marshall you get them all than ordinary that th handle it Two weeks to 1 e country over are rushing to take are interested, figure on getting your order Everyone predicts a serious sh rticulars today Send Coupon for Special ae If you have any idea of buying a radio s year, don’ We also have an yadio dea Marshall Radio enbieees Inc. Marshall Blvd. and 19th Street Dept. 13-67, Chicago Marshall Radio Products, Inc. Marshall Blvd. & 19th St., Dept. 13-67, Chicago Please send me your special off r pr re, terms ar f description of Marshall Ra On ts Tt gh I may ange my mind on receiving your proposition, my ¢ f- PTTL erence now is for a 3 Tube . 4 Tube Tube (Please check) Nam A e * I, \ e )

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HOME a DO YOU WANT IMPROVED TUNING? BREMER-TULLY LOW LOSS “LIFETIME’”’ CONDENSER 13 plate - = = $4.50 23 plate - - = $5.00 35 plate - - = $6.50 Pen ae larantee it res, I lore esse ge st ther N tter what circuit you’re using tl ner Tully ‘“Lifetime”’ cor undoubtedly improve it. te for “20-point”’ folder telling ' wl BREMER-TULLY Leads again with a new real LOW LOSS TUNER Gives Results Heretofore Impossible roved method of inductance ijustable untuned prin 1eets the great problem of nied t1 tuner the e, circuit requuire- mts and lao ving conditions tments permits greater selectiv ty or creased signal strength as desired. Two types For Broad meters, for short wave work Price $5.00. Better tuning (now tells you why and shows you how. Com- plete instructions and Pte am for pro- gressive construction from Crystal to Re flex and Radio Frequency Sent on receipt of ten cents BREMER-TULLY MFG. CO. 532 S. CANAL ST., CHICAGO, ww A past—th a to \ ous tyr = ad- in- 215-585 meter. neg ast 60-22 in sixth edition) circuits. Simple Vacuum- Tube Amplifier Replaces Megaphone By B. Francis Dashiell, M.E. HIS loudspeaking or signaling device is designed especially for use where it is necessary to transmit the voice across such as from ship to shore, from ship to ship, and for announcements during athletic contests. It is valuable in some cases on the farm. The device also might be used in directing airship land- ings. With the use of this set it is possible for the speaker to talk into the transmitter of the apparatus in an ordinary tone and have his voice amplified to such an extent arry perfectly many times farther space, or as to ¢ Announcer using portable loudspeaking out- fit to introduce boxers in a large stadium The causes and the understand an is possible with a megaphone. use > of a me ~gaphone, or like device, the speaker to strain his voice lieben er often unable to easily what is being said. The entire apparatus is contained in a small box, which is portable and may be fitted with jacks for plugging in the trans- mitter and the loudspeaking horn. On shipboard, the box may be placed where convenient. The transmitter is on the bridge, and a horn on either side of the is vessel is connected by means of a switch- | Wiring di hook-up is used in this amplifying device agram showing how familiar radio g arrangement at the transmitter so that a horn on the side of the vessel next to the pier may be used. The apparatus consists of a series of amplifying radio tubes and_ audio frequency amplifying transformers con- nected somewhat similarly with the usual audio-amplification stage of a radio re- ceiving set. Too many tubes can not be used unless great care is exercised in the se- lection and wiring of the parts. However, (Continued on page 135) in }}ORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY Newly Discovered Paste Shines All Shoes Rece ntly a chemist invented a remarkable paste which shines any shoes. This amazing new kind of p ste is cream white in color and comes in a con- venient tube. It is only necessary to apply a little ind rub with a soft rag. Immediately a lustrous fin- appears on black, tan, brown or patent leather oes. ‘his paste known as CEROLA, It ftens and preserves the leather and will not stain the hands or clothing. CEROLA is now demanded by particular people everywhere. Mer and women are making amazing incomes introduc- g this and other Harley specialties to their friend and neighbors. The big Harley line consists of Food Products, Spices, Fl g Extracts, Toilet Preparations, Home eee I other h 2 used every day ir ‘ry home. If you ke $15, $20 or $30 a week in your spar vermanent, profitable me work, write t larley Co., Dept 380-L, Third & Cl ton, Ohio, for free infor ation which te ] 1 in a free assortment “these famous food ales xdu THE S. C. HARLEY co. mi 389- iL Dayton, Ohio Don’t throw away This stropper gets as lov smooth shaves from we a blade. Automatically re- ver es blade, sharpens > ~ both edgesatonce. Guar- )\ anteed for life. io = yn a Ss em KANNERS eg 50 Dubeledge Stropper Models: For Gillette: Durham Duplex; allsingleedga blades. Order now—pay when you receive stropper AGENTS WANTED Samuel Kanner, 73-F 10‘ Street, Long Island City,NY BOYS! BOYS! BOYS! o 2THROW YOUR Into a trunk, under the bed or anywhere. Lots of Fun fooling f the Teacher, Policeman or \ Friends, THE VENTRILO, a little instrument, fits in the mo ry * ut of sight, used with above for Bird Calls, etc. Anyone can use It. NEVER FAILS, Also a 32 PAGE BOOK which gives full instructions on Ventriloquism, Formuls for Secret Waiting [Invi sible Ink], 12 Money Making Secrets 0 od 10 BIG TRICKS ON MAGIC all tor [OZ ROY. NOV. CO., Dept. 717 Norwalk, Conn. Mai! Order Housein Connecticut. MAKE MONEY. AT HOME you can earn agg your sp re tir No canvassing or s how, supply both money at home in making show cards’ citing. We show you men and women work at ne no matter where you live and pay you cash each week. Full particulars and book- let free. Write to-day. AMERICAN SHOW CARD SYSTEM LIMITED 206 Adams Building Toronto, Canada Daytime System Nighttime protection for your tools pro- vided by Cerstner Tool Cases for MACHINISTS and TOOLMAKERS Write for Free Catalog. H. GERSTNER & SONS 510 Columbia St., Dayton, 0. Do You Need Financial Aid? | Financial aid givenin the development and marketing for you of any new metal auto- | mobile specialty. Let us help you work out your idea. Write today naming item. | THE METAL SPECIALTY CO. 1535 W. 6th St., Cincinnati, ° 4,

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| ing, especially when a Old Binding Nuts Useful for Kmergency Radio Connections N ALMOST every handy-man’s or | radio fan’s ‘‘catch-all’’ box may be | found thumb-nuts from discarded dry | cells and also 8-82 machine screws of | various lengths. These, when used illustrated, are a great d : i | help in radio and other CF an you electrical experiment- hurried connection or extension of wire must be made for testing purposes. This little kink saved me from em- barrassment one eve- ning and Lam confident others will welcome the several binding posts suggestion. —H. WENZ. used on one screw

DISCARDED THUM B-NUTS

Testing a Radio Receiving Set for Battery Connections HERE is an easy way to find out whether a radio B battery is con- nected with the filament or A-battery circuit without the necessity of using a voltmeter. Before making the battery connections, | connect one terminal of the A battery with the positive A-battery terminal of the set and try the other terminal of the A battery on the various positive B- battery terminals. Next, connect the positive of the A | battery with the negative A-battery | terminal of the set and try the negative of the A battery on the various positive B-battery terminals of the set. Have the tubes in and the rheostats turned on. Then, if the tubes do not light up, it is safe to connect the B batteries into the circuit. If the tubes light, it will pay you to check up on the connections.

Amplifier Replaces Megaphone | (Continued from page 134) te det Jroi ge £. Free Trial our amazing typewri her offer except to two or three tubes and transformers will | Big Book FREE You have ten full days pte te pe ' give a powerful amplification that will | earry long distances, provided suitable | f loud-speaking horns are used. An ordinary telephone transmitter is used. It should be connected with the primary of an audio-frequency trans- former using one dry battery cell, with a | potentiometer to regulate the current | flowing through the transmitter.

The secondary of the transformer is connected with the grid of the first tube, of either the 114-volt or 6-volt type, HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE Genuine Underwood it from a brand-new Underwood all ar me your benefit. Send in the coupon | either in appearance, durability or 2 : and we will send you prepaid our quality of finished work. Send wirtan big : includ a PATHFINDER, 559 Langdon Sta., Washington, D.C. for $1.00; se nd. stemp e, Os

yin or money order AUTOMATIC RUBBER CO., Dept. 22, COLUMBIA. S. C ARN GOOD MONE Be a Bricklayer

2 C. BROADCASTING TAKE AND SHO YOUR OWN movies ovies of your family

Come to Michigan and learn brik aying at a school operated by Buik sing C mitractor “ iths’ day course. Evening course aite op eg ig Wri te today ASSOCIATED BUILDING EMPLOYERS 1120 A. B. E. Building, Grand Rapids, Michigan PARAMOUNT MFG. COMPANY Dept. PS-5 Boston, Mass

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HOME

Tested and Listed as Standard by Underwriters’ Laboratories

A noiseless bulbless radio battery charger Entering the field late last year, the Balkite Battery Charger is today universally accepted as one of the most efficient and_ trouble-free methods of charging radio batteries. [his charger is entirely noiseless. . It cannot deteriorate through use or 3. It has no moving parts or buibs. 4. It has nothing to adjust break or get out of order. 5. It cannot discharge or short-circuit the battery. 6. It requires no attention other than an occasicnal filling with distilled water. 7. it delivers a taper charge, und cannot damage the battery by overcharging. 8, It cannot fail to operate Ww hen connected to the battery and line current. 9. It is unatlected by temperature or fluctuations in line current. 10. It is simple, efficient and indestructible except through abuse. 11. Without added attachments the charger may also be used to charge “B” storage batteries. 12. It can be used while the set is in operation without disturbing sounds. 1 s ~ disuse, The Fansteel Balkite Battery Charger will charge the ordinary 6 volt radio or auto- mobile storage battery at 3 amperes, from 110-120 AC, 50-60 cycle current. Manufactured by Fansteel Products Company, Inc. North Chicago, Illinois Price $19.50 West of Rockies $20 In Canada $27.50 At your dealer’s. If your dealer annot supply you, sent prepaid on receipt of price rs) Balkite ‘Battery Charger

WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY Winder for Making Radio Coils By L. B. Robbins WINDER is a necessity for the radio experimenter who makes many The one illustrated at the top of the accompanying illustration can be made easily by the amateur and will save many hours of arduous labor. It is designed primarily to wind plain, cylindrical coils, but three attachments be made by which basket, spider honeycomb coils may be wound. The base is a board about 6 by 18 in. with a 5-in. upright at each end. A deep groove in the top of each upright acts as i the shaft. Caps over each bearing hold the shaft in while operating, but can be swung to allow the shaft to be taken out n desired. The shaft is of 14-in. ~square iron or steel coils. can and bearing for « id asiae whe

rounded at each end. One end should MOVABLE FA —— CYLINDER-*

yy MW Phas y/ game Lee A 3 muti

FOR BASKET COILS oii J B FOR SPIDERWEB COILS 1 3 > ? » IQNAILS _ fatto ‘ a ™ ap 37 ¥Cc PT he = 2.2368 =~ <©° Cee JA | — eS 194 js- AYLILA if I\\" C FOR HONEYCOMB COILS The winder with cones for holding tube forms and fixtures for special coils be threaded and furnished with two lock- nuts for a crank. Two wooden cones, as illustrated, serve as the coil-mounting holders. They made of wooden disks connected by thin The large end is 4!4-in. in diameter and the small end 21% in. in diameter One should be fixed permanently to the shaft; the other has a hub block with a setscrew to allow adjustments. A eylinder is placed in Sage by re- moving this cone, lifting the shaft, slip- ping the cylinder in place, and then re- placing the shaft and pushing the two cones together. Attachment A are slats. is for winding basket It is a disk 5 in. in diameter, with nails evenly spaced in a 4-in. circle 20 nails in a 3-in. circle. The larger the stator coil and the smaller rotor. The nails must be removed This fixture is placed on coils. 24 and winds the after winding.

the shaft in place of a cone and is held by a setscrew. Attachment B four down is a similar disk with screws near the rim for fastening the spider form. The setscrew block should be on the opposite side. For winding honeycomb coils use a wooden cylinder, C, 4 in. long and 2 in diameter. Drive two rows of 19 nails each around the circumference, parallel with each other and 7% in. apart. A hole then should be drilled through the exact center and a retaining screw and block fastened to one end. Setting Radio Dials Quickly \ Y MOTHER, who is quite old, enjoys listen- ing to radio pro- grams, but does not care to tune in stations by the usual hit-or-miss fashion. To allow

her to turn in- stantly to the sta- tion she wished, I cut a cardboard disk and fastened it with a nut to the knob section of a two-part dial. The old dial was discarded and the new cardboard one marked to show where each station could be tuned in.—R. A. KELLY. Adjustable Loop Aerial for Use with Super-Heterodyne LOOP aerial that is adjustable in length to suit receiving conditions and therefore is especially suitable for sets of the super-heterodyne type, may be made easily by the method illustrated. A frame of conventional design is made of '4 by 1 in. white pine, with a round or The arms are studded with such as photographers square base. glass-head pins, , [eke 2 bake) Ag GLASS-HEAD P lA K Gf yp es - Gp A Vii) Y Vl af Ah, TNX Ys \) A i a a€ yy “1, « Hate \ Vi Yp A, FLAT BRAIDED COPPER WIRE PHOTOGRAPHERS —, IRAP pins

LOOP ANTENNA

ee — ay By adjusting the clip, any number of turns may be included in the loop circuit use. On these pins is wound a length of bare, braided copper wire. One end of the winding is fastened to the pin in the center, and the other to a binding post on the radio panel. Connect a short piece of flexible wire with the other binding post and solder a clip on the loose end, so that it may be snapped on the loop at any place. This allows the closest possible tuning of the aerial circuit.— GEORGE A. MOHL, Buffalo, N.Y.

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Safety Strip icin’ Mix- sik of Radio Connections HERE is hardly a radio fan who at some time or other has not burnt out one or more tubes by connecting the bat- tery wires incorrectly. Even though a tube is not blown out, a wrong connection often gives a great deal of difficulty. A friend of mine tore down his set entirely before he discovered that the trouble he

} ]

it LATING MATERIAL The incoming wires are threaded through a marked strip of thin insulating material had been having was due only to a mix-up in the incoming wires. To aid in overcoming these difficulties, provide a safety connecting strip made as shown from any odd, thin, narrow piece of fiber, hard rubber, or other insulating composition. If there are six incoming wires, as is generally the case, pierce the strip with six rows of three holes each. Lace wires through them, as shown, and mark each wire distinctly.—PAuL A. DASCHKE, New York. Imitating Fumed Oak U MED oak is one of the most effectiv and popular finishes for plain or quarter-sawed oak furniture, but an air- tight box large enough for fumin; rarely available, especially in the home workshop. A similar finish can be obtained quite easily by making a stain of ordinary isphaltum varnish well diluted with tur- pentine. Thisis applied with a brush and wiped off with old cloths. A filler is not used, but, when the stain is well dried, give the wood a coat of orange shellac and finish with furniture wax well rubbed in. A dark wax is more effective than the natural color. This may be made by melting any standard wax in a double boiler and stirring in some ivory black mixed with a small amount of turpentine to break up the lumps. Great care should be taken because of the violently inflam- mable materials used. Keep a cover for the melting dish handy and if the wax should catch fire accidentally, clamp on the cover. The wax is used cold. The same method of finishing is effec- tive on interior woodwork.—S. W. B

Carpenter's s Handec rew Siu es as Bench Vise for Small Work A CARPEN- TER’S hand- screw made of hard maple, as it usually is, forms a_ practical bench vise for small work on brass or wood. T is handscrew is fas- tened near the edge of the bench with two wood screws, and a large nail, spike, or rod may be used, if desired, to turn the handle on the far side.—J. D. (

HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY

}

Will She Say) ~ the Second Time ? HE the last strains of the music ie faded away when the dance 1 over—you thank your partner and miles back at you. But is her smile force did she really enjoy the dance? \W say thes” when VOU a | her for the ( dance ? Does iny girl Want to dances clums y, awkward leader? Does she | ; to nbl tl \ falls f constan Why Good Dancers Are Popular | M1 ionyg >i I

t ici ) dancer VY , home with neit! mu par you need is Arthur Mur vondert home ~le »I in d \ | > le vou now t ' ) ) m i np as I ) i 7 + 1 ‘i lost po ‘ \ ‘ ll be 1 be able ) 1 follow with Manv oft tl ) \mer a | | Murra a I ) la Vv in Arthur Murray, Studio 275 Five Dancing Lessons FREE 06 Geenean Maw Fe Over 200,000 I 1 ) I } r y hing \ ne lo 235 rco pr t t tion whate ~ | S bs oe oe 0 | (

CLASS 25¢PINS

N a at home to mount birds, ani-< a mais, game heads; tant Ny __ gel DIRECT FROM THE MAKER tS r, ; roves. ¢ omplete lesa a8. Baniy and quickly CATALOG FREE : CRE N Wi ite a 5 "Free ‘Taxidermy Either pin shown made with any letters ar A 2 | 4 Ai N FREE E sions Bere sma a se figures 1 or 2 colors enamel, sinver plate 2 of y Nature er ss ua. w th ae naar ea. $2.50 doz. Sterling silver. 40¢ ea.. $4.00 ¢ ay N rot at - art - stale y u 6s . rofi Succ eed a BASTIAN BROS. CO, : Rates. loveseat. Write for bree f 591 Bastian Bidg., Rochester, Foss | [Norshwestere School of oe 1787 Elwood ‘Bldg Omaha Neb.

Convert any cook stove, range or heater into a re< al gas stove. OXO-GAS. the ch eapest, cleanest and mostefficient fuel known to science, is mz - right in your own stove from kerosene or distillate and air. Burns a pure, blue flame of high heating intensity as silently as city gas,

Send for catalog illustrating and describing twenty different, distinctive designs of oil burners for Furnaces,Cook Stoves, Heating Stoves, Base Burners, Hot Water Heaters, etc. AGENTS Some choice territory for Heat, plenty of it, in base WANTED OXO-GAS agencies still burner or heating stove. open to thoroughly responsible parties. Clean, satisfactory, eco- Yourown locality may yet be unassigned. nomical, convenient as ‘ steam heat. Brings happi- GLORIA LIGHT co, Burner i ness, plus. 103-10 North May Street, Chicago, Illinois

e OXO-GA fina f

s da

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His Iver Johnson Has Been On Duty 25 Years EAD what Mr. J. S. Van Voorhis of New Jersey has t the Iver Johnson oO say about > 5) : Revolver: ‘I have had this revolver for twenty-five years. Have used it iot duty thing of four years as a n service aS Well aS ONT + , > tO Say n pocket gun—while a member of the Pennsylvania Constabulary. The fact that it has never been t of order speaks for itself.”’ f service can certainly be de pended upon to stand by you should an emergency ever arise. Keep an Iver in your home Johnson Revolver as a guarantee ol protection. The ious Saf H ill Re ] é le ing he cylinde toy ppe I tr maximum it Handsomely designed, finished in blue, k er copper. 22, 32, 32 Special six shots, and 38 caliber hammer and 2 ls with Regular, Per b Pear] Western Walnut griy Barrel lengths, from two to six i es inclusi Send for FREE Booklet illustrates and describes the of Iver Johnson ‘(Hammer the lvers, as well as Iver Johnson gle Barrel Shot Guns and Ham Barrel Guns River Street. Fitchburg New York: 151 Chambers St Chicago: 108 W. Lake St San Francisco: 717 Market St IVER JOHNSON REVOLVERS IVER JOHNSON’S ARMS & CYCLE WORKS } Mass HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY Three-Sided Shield Hides This ceiling, bined with a } Antproof Garbage Can OUR angle irons, two lengths of strap iron, a few feet of tongue-and-groove and six 1 by 3 in. battens, com- it of ingenuity, will shield effectually the unsightly garbage can and lso eliminate the dreaded all-summer army of ants in localities where ants art troublesome. elevate the e, | Make three sections as shown, a little higher than the garbage can. Then, to WW Ny LO7 The shield in place and details of the stand, which is set in a pan of water take the two pieces of strap iron, each of which should I can from ants, longer than the diameter of the 6 In in, and bend the ends down 38 in. to form feet. Bend one iron down in the center, so hat when the other crosses it at right ngles the top will be level. Rivet the irons together at the center. The garbage can rests on this iron stand, the feet of which are placed in 1 large shallow pan of water so that ants nd beetles cannot climb up.—A. MAy HLOLADAY, San José, Calif Belt Splice Is Made Quickly with Ordinary Staples MALL staples may be used for making a cheap belt splice that will give as good service for ordinary work as com- mercial fasteners. A pair of pliers, a hammer, and a vise are the only tools needed. for fastening chicken wooden stick being used as a sure peen removed and the similarly The staples, which are of the type used netting, are placed bent as shown with the Then they are fastened at regular the vise and the end of the belt, a small ervals over the How belt splice is made guide to in- uniformity. When the points have driven into the leather, the stick is other end of the belt is treated The two ends are brought together and a long cotter pin or else a piece of wire is pushed through the loops One advantage of this type of splice for use around the farm is that one belt may he inserting pieces to lengthen it.—J. J. B. used for many different purposes by 2 Nothing about the DUOPLUG complicated It takes two headsets—and is SO simple that no tools are necessary to make connections. Unscrew the handle and look inside—you can tighten the special thumb-nut connectors with your fingers, and be as- sured of a secure and perfect contact. A substantial plug—with genu- ine bakelite handle and heavily nickeled metal parts. Good radio shops have it—at $1.00. Pacent Electric Company, Inc. 22 Park Place, New York, N.Y. PACENT Radio Essentials For a Generation of Daily Use A generation of daily usage is built into every WHITING - ADAMS Shaving Brush. WHITING - ADAMS BRUSHES work perfectly and hold to- gether until actually worn out. WHITING -ADAMS BRUSHES The satisfaction of using a WHITING- ADAMS Shaving Brush increases day by day. They satisfy —serve—and survive ! JOHN L. WHITING-J. J. ADAMS CO., BOSTON, U. S. A. 3rush Mancvfacturers for Over 116 years and the Largest in the World The Electrician’s Wiring Manual By F. E. Sengstock, E. E. Contains all the information needed for the proper installation of lighting and power systems in housing and other buildings. It completely covers inside elec- trical wiring and construction in accordance with the National Electrical Code Pocket size —fcxible binding 448 pp. Price $2.50 POPULAR SCIENCE MONTHLY 250 Fourth Ave., New York City

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A Sea Scooter with Air Propeller Is a Novel Toy N ODELED somewhat after the style of a racing seaplane, the toy scooter illustrated, if properly constructed, wil travel quite rapidly for a short distance. | propeller, but the works of a dismantled clock or a toy spring motor can, with a bit of ingenuity, be rigged up as the power plant. The hull is fashioned from a piece of white pine 2 in. thick, 6 in. wide, and 15 in. long. The shaping is done with plane and chisel. The cockpit is cleaned out with augur bit and chisel, a half- inch ridge being left along the center

This shaped hull seaplane toy has a wooden of a fascinating like that racing

otherwise the bottom would be too thin there. \ rudder is made by soldering a piece of tin, properly shaped, to a piece of wire, which is then placed and bent as shown. There is considerable vibration, so it necessary to brace very rigidly the engine” and the part that holds the propeller. This done by means of pieces of wire having the ends bent to form eyes, held in place by screws. The propeller should be modeled after those used in airplanes. Soft pine whittles easily and is satisfactory. Bend the end of the shaft and fasten it to the hub of the propeller with a double-pointed tack. iS ‘6 is Decorate the scooter after the fashion of | racing boats, paint a name on the bow, and you will have built a boat that will be the envy of all.— KENNETH R. LAVoy.

Cheap Shopping ‘Bag Serves as Landing Net Emergency ECENTLY I found myself near plenty of good fishing and able to procure all the necessary tackle except a landing net. As a landing net is almost a necessity for a game fish hooked on light tackle, I set to work to im- provise one. Looking around a country store I found a 20-cent mesh shopping bag for the net. For a handle and frame I used a forked sapling of hard wood, as illustrated.—S. B.

How a fisherman may improvise a net A rubber band is used to turn the air |

HOME WORKSHUP DEPARI MENT OF POPULAR SCIENCE MONTHLY

at oi AL rs Q a Santa Le Special 21 Perfect Jewels Adjusted to Positions Adjusted to Temperature Adjusted to Isochronism Adjusted to the Second 25 Year Gold Strata Case Your choice of Dials Mg Montgomery R. Dial) New Thin Models, Ail Sizes, proud \ ,' YHILE other watch dealers ing their prices, asking you for] larger monthly payments, and mak- ing payment terms harder for you to meet, we are offering you our new model Santa Ke Special, no advance in price, down, easier terms and smaller payments. We realize the war is over in order to double our business we MUST | give you pre-war inducements, better | prices, easier terms, and smaller payments. | oO ne | | }

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| are rais- monthly | and Send No Money Without one your hs to in in inds inspect, vance to see, to payment let us place to approve a admire, | watch to maste rpie ce examine, real creation. Our determination to this year double our sales of the world famous Santa Fe Special and Bunn Special Watches prompts this matchless offer. Ladies’ Wrist Watech—New Elite This Artisti nen ble , 1 Vat fitted with genu I Sy nge- ld movement \ perf rt ¢ € Deau- tif 11 14 Karat white or green solid gold « e Many desi Ask for New Watch Book showing Ni y g in Watch sent on ap] Land n } nts Page 12 of Our Watch Book Is of

Special Interest to You! | Ask for our Watch Book fre then select the watch you would like to see, either the famous Santa Fe Special or the 6-posi- tion Bunn Special, and let us explain our easy payment plan and send the watcl express prepaid, for you to examine No, money down. , SANTA FE WATCH CO., t REMEMBER—No money down—easy p Ly | A-80 Thomas Bldg., Topeka, Kan. ments buys a master ens a 21- ‘lease § nd prey t ° Jewel guaranteed for a lifetin at about] ms it ‘ , 1 half the price you pay for a sin aflar wa chy Ml r . | of other makes, No money down, A won- at | derful offer. t SANTA FE WATCH COMPANY \ 7 ' A-80 Thomas Bldg. Topeka, Kansas, , j “Home of the Great Santa Fe Railway” Ne ’ — aor EE Aa ne 4G. OS ~o C®, CGE BIT mens Dynamos, Motors, Battery ——e Farm Plants Motor - Generators, Etc. 3 K.w. $§39-50 5% 10 K.W. Any voltage Fit

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SOLES SRR OT BAU BURGESS RADIO BATTERIES OMETIMES it’s Dad who does the buying for his radio family, but you may besurethat that youngster of his sits in on the advisory board. In all events, whether it be the boy or his father who buys receiving set equipment, the service of Burgess Radio Bat- teries provides a most satisfac- tory and economical means to greater enjoyment of the even- ing’s radio entertainment. “ASK ANY RADIO ENGINEER” Encinecers - DRY BATTERIES - FLASHLIGHT + RADIO IGNITION GENERAL SALES OFF LABORATORIES AND WoRKS BRANCHES REW YORK BOSTON KANSAS MINNEAPOLIS SASH NGTON PITTSBUR NEW ORLEANS IN CANADA PLANTS NIAGARA FALLS AND WINNIPEG BRANCHES: TORONTO MONTREAL ST, Jone © gee BSS “See! Dad, how much stronger it’s coming in since you bought me BURGESS BATTERY COMPANY MANUFACTURERS TELEPHONE E HARRIS TRUST BLDG.. CHICAGO MADISON, WISCONSIN ATT ET GGT HOME WORKSHOP DEPARTMENT OF POPULAR SCIENCE MONTHLY Miniature House Insures a Warm Shelter for Watch-Dog “Can you furnish me with a good design for a dog house?’’ is a request received at intervals from_ readers of the Home Workshop Department The excellent design shown below will answer the majority of these questions. A GOOD dog is worthy of a good home. At least that is what one Nebraska farmer believes. So he has made for his watch-dog a small but com- fortable home that is attractive and weathertight. The floor is elevated above the ground so that it is always dry and warm. The house is 2 ft. wide and 3 ft. 4 in. long, with a shingled roof and ‘‘trim”’ like that of a house. One important feature floor roof A raised joints make this a weatherproof dog-house shingled and tight legs, which anchor it to the Some sort of anchorage is im- building so small might be toppled over in a strong wind. The pipes ppl 1a St ng ind. he pipes Is the gaspipe ground. perative, aS a extend two feet in the ground and the tops are bolted to the corners of the building ll 1g. The house faces the east cleaned when necessary. HORN, Walton, Neb. and is readily DALE R. VAN Special Lettering Pens Made from Ordinary Steel Points ipblitcetgpaetcrh pens, with — which the ama- teur draftsman { Fee can do a fair (| yt grade of bold f is hand lettering Cd yi without much 2 -\ practice, can be J “s made in a ment with aid of a pair of old shears from ordinary steel penpoints. Simply remove a portion of the point, as in Fig. 1. —_——— In Fig. 2 it will oS mene ie that the a more the points Sos ARNT are cut away, the Fig. 2. A set of pens mo- Fig. 1. Cutting the po pen nt with old scissors seen wider will be the lettering made by the pen. Use the pens in an ordinary penholder. For ink, use writing fluid with several pinches of gum arabic dis- solved in it—-KENNETH B. MURRAY. Gs 5 te % train N° 690 is a wonder- S ] 520 HEN you see it you will be as tonished that such a large, fin tra operating on No. 2144 Gauge Track, can be sold for such a reason ble price. It represents a new value in miniature railroad outfits. There are many splendid new fea- tures in the 1924 Ives Railway Lines. Foremost among them is the wonder- ful Ives electrically-reversing locomo- we 1° : ° Ss new electric n af- vel, running at express speed, and then verse it | ns of the control switch located away from the track. It’s the only toy locomotive in the rid that reverses electrically. - , Train No. 690 R $19.50 HIS train is the me in ever respect jo. 690, but the locomotive is ped with reversing motor de- ribed at Pe, Ii } as no equal! Ives Toys make happy boys M upon below for book describing a istrating the Ives mechanical and el ns for boys of all ages, and at prices rar f 1 $1.50 to $50.00 Toy, ardware and partment stores sell Ives Trains. THE IVES MANUFACTURING CORPORATION 197 Holland Ave., Bridgeport, Conn. IVES CTR ae Ic Tie Bens: Ai iashachiing Corsocktica 197 Holland Ave., Bridgeport, Conn P c ur 32 page r vad | c owing the te | | I I s, new Siz and A | I 10 (I S. stamy r | | } Gc Er reh vee | | | Cay ccakkooeasae hecee ence State 1| B Tams

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A Triumph for the Airplane (Continued from page 34) intentions of turning into a_ swan! At a casual glance the Liberty motor used in the round-the-world flight today | is the same motor that was turned out in | huge quantities during the war. And | yet it is a different motor in more than 600 vital particulars. Little refinements have transformed it from a mechanism of questionable value into an internal com- bustion engine of the highest efficiency ever attained. In all Army flying since the war, when- ever a motor part broke or failed, it was sent to the technical section for examina- tion and test. And not only was the defect remedied in that particular motor, but every motor in service, and every motor thereafter placed in service w changed to conform. as HAT is the way the reliability, staunchness and durability of the Liberty motor were developed—little by little through a total of more than 600 changes, some of them trifling but tre- mendous in their cumulative effect. Nor was this new efficiency won without sacrifice. Many pilots and observers died martyrs to the effort to improve the Army Air Service and to point the way to the development of commercial aviation. And the result? It is not ar to look to the world flight to find i In two years not a single plane flyin g » from Mitchel Field has had to descend because of motor trouble. Army planes now give 98 per cent continuous performance. A plane flies for 160 hours; then, whether it shows signs of wear or not, it hauled and made ready for the air is over- again. Which is equivalent to saying that an | ordinary stock plane is expected to | stand up for a period of flying about | equal to that consumed in, say, five trans-continental flights. Early this summer I got an idea one morning that I’d like to pay my parents a little surprise call. They live at Colum- Nebraska, and I was at Mitchel Field, approximately 1385 miles away. I got into a stock plane of the HD model, and I took dinner at my old home that evening. Moreover, there was an hour and a half to spare before dinner. On the return trip I visited several Western cities with greater convenience than could have been obtained by any other means of transportation—and the plane has been running ever since without the slightest sign of trouble. bus, * AN you imagine a locomotive ac- complishing any such trip as that— more than 3,000 miles, with the throttle wide open all the way, stopping only for fuel and oil? You can’t, because locomotive ever made was capable of such service. Observe the next time you take a long railroad journey with what frequency the locomotive is changed; you'll probably be astonished to note that a new engine is pulling your train every couple of hundred miles. no Of course, other phases of aviation were not at a standstill while the Army Air Service was taking the “‘bugs’”’ out of the Liberty motor, as those in the service (Continued on page 142 POPULAR SCIENCE MONTHLY Why Does a Fellow Talk About His Lionel? Much } OOKS just like my Lionel, doesn’t it?” That is wh . i! boy said at the movies as the Express came rus a along the track, a | 7 Boys are always comparing their Lionel Electric Trains to real +] because they know how real Lionel Trains are. The only differ j j between Lionel and real railroads is the size. i j Since 19¢ 0 Lionel has specialized exclusively in th manufact } model el lectric railways. Lionel makes true model trains and equipmen | —not mere “toys.” } } Lionel trains and enn are fine looking, of course, but even n | important than their distinctive beauty is the engineering skill, th ! ey b terial and workmanship that go into their manvutac- ! 4 ture—they are electrically and mechay illy perfe | And this is why “Lionel Standard” and “O”'G — Trains are far and away the most popularinAmerica 7 jo), a eer? today. Tra You can buy a complete Lionel Tr: 1in from $§.75 ereal up | slightly more in the far west). é than at | 1. men ing toy stores, department stores, electric sl Sy r | Lionel “ Multi- sporting goods and haraware stores. § | volt’’Transform- Be sure to write today for the handsome 44-page | ers. Ever-reliable Lionel catalog illustrated in 4 colors. Sent FREE. ly power plants. THE LIONEL CORPORATION Dept. B., 48-52 E. 21st St., New York City fine of TIONED STRAIN Run all trains best. A type for every size train. sOTIeS. Make'l00aWeek IN THIS FREE FORD BLANK CARTRIDGE PISTOL | . Protection against Burglars, Tramps, & Dogs aoe ——y iG want a few more men to ridear gry ving ar PoSsT- ribu sg dyes us Harley line of Groceries, Tea Coffees, Spices, Flavoring Extracts, Toilet I aratior | Home Remedies, ‘and ‘ rt 1 ne N Well made and ef- experience ne ssary.8 av ear! t fective; modelled on ent work. I pay are t . 8 pan! latest type of a Iver: free sa eass ] appearan ne ie ri fs t , care: ae urglar f ation ar EE FO test aded it may be as Costs y im g to start every ctive 8a real revol th It takes standard .22 fank Cartridges btainable everywhere. Price 50c. Superior quality $1. ‘00 Postpaid, Blank Cartridges, by express, 50c per 10 Johnson Smith & Co., Dept. 163, "Racine, Wis. ut danger to life. THE E. C. HARLEY | COMPANY 650-L Harley Bldg. Dayton, Ohio - (TER PRICES cur ee ie REGISTERED PATENT ATTORNEY SINCE 1905 2 ’ may,» CHARLES W LOVETT Smt 8 (YAN MA35 and it S yours Aa Ns Ma SEND FOR FREE BOOKLET r eis, completels rerun enase~ ewe 7S Free YE AF e ; ca ee WV Trial Satekcatinual emauitor? EX. “ ‘186 wW. ‘ion ake st. Chi 220 Develop Your Ideas At Home! It is easy to build all kinds of things with a BOICE-CRANE JUNIOR SAW It will saw, sand, grind, miter, rabbet, tenon and many other operations with ease and accuracy Saws | stock Dadoes 5,'' x Driven h.p. motor attached to any light so cket SOLD ON MONEY BACK GU ee lder t bern r Write for descriptive f “Buzz Boice” vill be you. W. ‘& as BOICE, ian, PS. 10, Toledo, ©

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This loudspeaker is made of a new light- weigh naterial which eliminates rattling and rasping Requires no bi atteries 2rates on all ordinary plate voltages, 45 J 14 high Choice of artistic f he Write for Free Descr tive folder © ore ad LOUDSPEAKER

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reflect j s k € I " € ¢ to f the: Its sn an I An 7 id 1 1 hes, w ar i 1e dé l It s ne Burtex, a itifi prod N ke br wood or metal pre S br: is ¥. ating unpleas ig cn r I S ngl mellow N fr thus Ps S tical Listen new invention on your own s We ze N & K Dealers to Loe t responsib t r FIVE DAY $ FREE TRIAL te with 6 foot cord, $27.50. If i yet nines i, notify t I midt Cc rporat ion Dept s.9 15 W ‘Nev w York Ci and you will be given prompt opportunity to listen to this new N & K wil a prot Me aker

Made by the makers of N & K Imported Model D, 4000 Ohms. Price $8.50 Phones,

Th Loudspeaker has made an instant sensational success wherever displayed Tt is big pr aker because it eets eI nand pu ipon high grad idspeakers ye quality ppearan price. If yur regular ' bb cannot supf U rite us for name of nearby N & K | authorized Distributor | | Th. Goldschmidt Corporation ; Dept. C-10, 15 William St., N.Y. C. i

POPULAR SCIENCE MONTHLY

A? Triumph for: the Airplane 141 ( ‘0? tl nued ron pa ge i describe the process of bringing about the many refinements that have resulted in its present efficiency. New equipment of many sorts contributes to the comfort and efficiency of the modern air pilot. The earth inductor compass, for example, with which the round-the-world planes were equipped, enables a pilot tc main- tain his course independent of fog, snow, in, or hail. This instrument, a series of coils set earth’s magnetic ra developed recently, is in ition to the es of f and rotated tby induction. connected with a delicate the cockpit and are oppos lir yrce rapidly to produce a curren These are galvanometer in 4 | cols so arranged that when the airplane travels its predete rmined course the coils rotate long the line of the earth’s magnetism, and nduced. however, coils to cut the magne no current is i from that course, Any de viation will cause the tic lines of force of the earth and so generate a current, moving the needle of the galvanometer and thus permitting the pilot to see how far he is off course. It was this instrument, undoubtedly, which permitted the world pilots to pass safely through the fog and snow encountered off the Aleutian Islands. eee camer he altimeter, is apparatus that empl to enable a pilot a his exact height or his exact from any object he may be f condenser Oys 4 ) static elec ctrici ty Lways to determine distance ppr oaching, is of prime importance inso venturesome an undertaking as a world- flight, in which the pilot is almost con- stantly flying over strange country. The world-flight is an |-American ndertaki 1g j every sense of the term Planned and sponsored by the flying arm cf the country’s land forces, it is carried out by soldiers of the United States Army in planes designed and constructed by an it] A moriea \merican aeronautical engineer—Donald Douglas—and that get their power from n engine the de velopment of which is a triumph of American ingenuity, industry and sl at The Douglas World Fliers, as the planes are called, are a modification of the Douglas torpedo plane. A thicker wing section, demountable pontoons that per- mit the planes to land on, and take off from water as well as land, and other body refinements fitted the Douglas mach iH Lodge rs ontinental fli ress in av ines for their epoch-making journey. ARKING back to the and his a ight, and recallir iation since then, can be made for the rs? Will men of the asually as the a dozen states? I hesitate to make One thing I will say, my days of Cal day trans- ig the prog- what predic- next air girdle tl now ver e dozen : ne as Cc pass proj yhe Sy. at in full con prediction will i is, that matter what de oo in aviation come in the futu Americans then, as now, will ars forth the leaders of the world. a speci % 1 idence’ that fid fulfilled. That no Next yrwwag? —A rem: arkable pictorial story of the Navy’s new peace airship ZR-3, and her warlike sister, th» Shen- | andoah.

You can be expected, anticipat- ed, welcomed with open arms. You canbe a favorite at parties, dances and other social affairs. The charm of jazz refined is yours with a Buescher Saxo- phone. Young folks find those syncopated tunes simply irre- sistible.

SAXOPHONE | r , , | You don’t have to “‘study”’ the Sax- | ophone as you do other instruments.

There’s no practice drudgery. You don’t have to be ‘‘talented.” Three lessons sent free with the in- rument start you. Ina week you can play popular airs. No teacher needed. It’s all fun, and even though you’re only interested for pleasure now, you can, in 90 days’ time, join a band or orchestra, if you wish. First class Saxophonists make big money. Try it ae for six days in your own home. Free Saxophone Book — Send a postal for your copy. Mention any other egies nt in which you may be interested. No obliga- ion. Do this today. (127) Str BUESCHER BAND INSTRUMENT CO. Everything in Band and Orchestra Instruments 206 Buescher Block, Elkhart, Ind.

s “ . « Buescher Band Instrument Co. ® * 206 Buescher Block, Elkhart, Ind. = ® Gentlemer 4 7 Rie id . I rested in the instrument checked below: e < t ( net l'rombone Trumpet : « 1 therin ument interested in) . . . . . . . . . . dd 2 . . . ” e J ’ State . . emeceeeeeeenear~ Seeeeeeeeeeeeeeeeeeeeeeeee

Page 143

You Can Save Your Wife 10,000 Steps a Day (Continued from page 82) material. Here is where the experienced architect, builder and dealer know how to save hundreds of dollars. If all the dressers, the breakfast nook, table and benches, and other woodwork have to be made specially at the mill or in part, at least, by the carpenter on the job, the arrangement is not practical because the cost is disproportionately large. Two families that I know of each are building a house from the same archi- tectural plans and in the same city. The details for special built-in woodwork were drawn to scale carefully by the architect and were reproduced in the blueprints. The head of one family had his con- tractor order all of this specially designed woodwork specially turned out at a local mill. In the other family, the housewife studied various stock woodwork or mill- work catalogs and bought stock designs of built-in furniture that closely re- sembled the architect’s designs. The difference in cost saved her about $259, and about $100 of this saving was in the built-in kitchen equipment. HIS woman discovered that in every lumber dealer’s stock a wide variety of millwork is available, and that designs and sizes which are not in stock can be ordered from catalog. In any type of stock woodwork there is an unexpected range of choice in dimensions andstyle. Dressers, for example, may have glass or panel doors, and they may extend to the ceiling or not as you wish. Bins and drawer sections are interchangeable so that almost any desired combination is possible. Used singly or in group as- semblies, such units will fit into compact space in kitchens already built, as well as in newly constructed kitchens. Most architects and builders now provide comfortably sized kitchens for their clients. A builder of small houses who has sold more’ than 2000 five-, six-, and seven-room homes during the past two years told me recently that women prefer a kitchen containing from 100 to 150 square feet, with plenty of built-in convenience and labor-saving features. This space, he has found, allows room, without crowding, for the equipment needed for the many household tasks that center in the kitchen, yet does not involve miles of walking for the worker. Unless the popular separate dining nook or breakfast alcove is provided, the kitchen should be large enough to be used for breakfasts and other informal meals. F your house was put up before built-in devices came into general use, you still may install some of them without costly alterations. Not long ago when I went to dinner at the home of a middle- aged couple, I observed that my hostess was limping slightly. ‘Have you met with an accident?” I inquired. “Yes.” she replied, ‘‘That dratted ironing board! It just fell out of the kitchen closet on my foot.’’ (Continued on page 144)

efficiency or u Court of Appeals,

POPULAR SCIENCE MONTHLY PROTECT YOUR IDEAS ANY NEW : ination of parts or

t 1 yrovement thereof, or any new , May is sateaed, i tion. If You Have Any New Id eas which you fee your cas Ta if arts, Or improvement, or any MODEL OR DESCRIPTION protection. 1d novel, tz eke prompt action to protect apes of Write Today for Blank Form ‘Record of Invention’’ USE THE COUPON att you this form to be return idea; promptly upon receiving

DRAFTING and SPECIFICATION ROOM of CLARENCE A. O'BRIEN, Registered Patent hanes Washington, D. ( No cigeaniel for Above Information All communications are thorough attention is given service—based upon practical exy WRITE TODAY for free b and Industry.’’ These books save you much time and effort. rict confidence. My per use. I I mu effi t nce. fiaslieas jaleanan. ‘“*How to Obtain a Patent”’ a ‘““‘Invention give you valuable informat Send for them NOW. My practice is devoted exclusively t to United States and | Trad sx gre Write me freely that ( elp vou Write TODAY. a A. O'BRIEN REGISTERED Member of Bar of District of Columbia, United States Court of Claims, Supreme Court of United States, Supreme Court, District of Columbia , frankly and th ft PATENT LAWYER Practice Confined to Patents, Trade Marks and Copyrights j-----;- FREE COUPON.-------- CLARENCE A. O’BRIEN, Registered Patent Lawyer, ' fashington, D. ¢ 887 Security Savings and Com’! Bank Building, directly across street from U.S. Patent Office. Ple id me n

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Page 144

POPULAR SCIENCE

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.\ Nine out of ten sets use Nine out of every ten sets are made with Micadons—the standard fixed radio condenser. Set builders choose them They know that the Micadon is a Dubilier product, hence superior in quality and efficiency. They know that Micadons can be obtained in accurately matched capacities and that the capacity is permanent. They know that Micadons are easily installed, equipped as they are with extension tabs for soldering and eyelets for Set screw assembly. They know that Micadons are made with type variations MICADONS!

or many reasons. oO meet every possible requirement. For the best results use MICADONS. ‘Dubilier CONDENSER AND RADIO CORPORATION

| How to Make} “Experiments With 110-Volt Alternating Things | Electrical | Cusnnat” Jet. € 771 POPUL 250 Fourth ot lea ] would ERE at last is a book that gives a practical working knowledge of the alternating current. VE Spice paar ight jor The only way to gain a thorough understanding of electricity is by direct personal experiment. How ¥ ir ee a practical knowledge of the alternating current can gig eagpe cag ae be gained in an interesting and inexpensive way is is shown. The knowledge that comes from experiment is of vastly more value than that acquired from the Make Things Electrical” performance of the stereotyped series of battery ex- : a I TET periments usually described in books on Alternating id d Current. mer) 3 The book “Experiments with 110-Volt Alternat- epee yf Gary tegen er a Re ing Current” is needed by every man experimenting Make Thi Electri ‘ with alternating current. 256 pases, 135 illustrations. Price, postpaid, $1.75 AR SCIENCE MONTHLY | POPULAR SCIENCE MONTHLY Avenue ew York City \ _' 250 Fourth Avenue | New York City

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You Can Save Your Wife 10,000 Steps a Day (Continued from page 143) | ‘Why don’t you have a built-in ironing board installed?’ I suggested. ‘In this old house?”’ she asked. I explained that to install such an iron- ing board in an old building, all that is necessary is to cut out lath, plaster and baseboard between two studdings that are about sixteen inches apart, to a height which will take the stock cabinet con- taining the hinged ironing board. First, of course, make sure that there are no obstructions such as pipes or wires between the studding to prevent the cabinet from going back the proper depth, about six inches. Nails fasten the cabinet in place between the studs. The stock door casing, door cap and door then can ve hung. My hostess followed my advice. On my next visit she led me out into the kitchen. There, practically flush with the wall, was a six-foot cabinet. She opened the door, and pulled down the large board, revealing a smaller board hinged just above. ‘There they are, as you see,”’ she said, ‘the big and the little. They are always in place; never fall down; are never in the way; require neither chairs nor table for support; are clean and free from dust, and are always ready for use. For convenience I have had an electric outlet installed next to the cabinet.’’ White enameled, it perfectly matched the other woodwork the kitchen.

N OST manufacturers of stock mill- + work and built-in furniture and equipment furnish the material assembled or partially so, in the natural wood, so that it can be finished on the job to suit. Hardware sometimes is supplied with it. Always buy good hardware. Inferior, cheap hardware, quickly rusts. Bronze or brass hardware is best and cheapest in the long run. There is nothing mysterious about built-in kitchen equipment. It has come to stay. Moveable kitchen units, of course, are avilable in both wood and steel; but the built-in kind seems to be steadily gaining in popularity in the average man’s house today. As an integral part of the house, these built-in features—particularly for the well equipped and well-planned kitchen very often sell the house, builders find. Every man and every woman construct- ing a home should remember that one day it may be necessary or desirable to sell that house. Details that lend com- fort, convenience and attractiveness com- bine to create a better home that should not be hard to dispose of almost any time at a good price. HY it is economy to build in permanent furniture in other rooms of your home—whether you are planning a new house or building over an old one—will be discussed by Mr. Moore in an early issue. He will show you how you can do it and will explain why built-in furniture increases floor space by taking its place as part of the

wall, increases property value, and is useful, peecticat: and decorative.

Page 145

| no good, and substitute deeper sleep of

| their night’s sleep if they will follow a few |; you

Do You Sleep Too Much? (Continued from page 43) most relaxed, your blood pressure lowest, and your skin sensitivity least. After the first couple of hours, sleep becomes lighter, After four hours it is very light. The slightest noise will awaken an average sleeper after this time. Now, to continue this light sleep in the morning is not restful. The extra hour’s sleep usually is made up of short naps broken sleep. It is beneficial neither your body not your mind. On the trary, it is likely to do you grave harm by helping build up a habit of laziness. to con- not, W eM light, then, do away with this | fitful slumber that does you shorter duration? Cut two or three hours from your night’s sleep and still obtain more rest than you do now? You can do it very easily if you can manage to take a noonday nap of less than an hour every day. You are usually drowsy at this time, and apparently nature intended you to sleep then. Forty- five minutes of deep, restful sleep at mid- day is equal to three or four hours of the light sleep you get from three to seven in the morning. If you can take this noonday nap, follow it with a short period of light exercise, such as rapid walking, to aid digestion. It may take you a few days to accustom yourself to sleeping during the day, but within a week you should be able to do it easily, and you will find yourself able to cut three orfour hoursatleastfrom your night’s sleep and still be stronger and more efficient both mentally and physically. Of course, I realize that it is difficult, if not impossible, for some people to take a nap at noon. Those who can’t, will find themselves improving the quality of simple rules for sleeping. To begin with, restful sleep depends on entire relaxation of the body. The only way can relax entirely is to lie at full length. Some animals can sleep standing up, but human beings seldom attempt anything like that. Still, I knew a man, several years ago, who would sleep while standing by his bed. There must be something wrong with a man like that, you are thinking. Very likely. When I knew him he was a patient in a hospital for the insane, which is about where all of us would end if we tried sleeping the way he did. JROBABLY you would find it impos- sible to do as he did. Muscular re- laxation is so essential to the sleep of maa beings that you can prevent your- self from sleeping by clenching your fist or bunching the muscles of your legs or arms. Conversely, you can coax slee p by relaxing every muscle of your body—your arms, legs, trunk, neck—even your ear muscles. The best way to do this is to sleep partly on your side—either side—and partly on your stomach. To sleep on your side will not permit entire relaxation, for some of your muscles must be kept tense to pre- vent you from rolling out of bed. Neither (Continued on page 146) POPULAR SCIENCE MONTHLY

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Do You nied Too Much? f l from page 145) Continued can by sleepin g on your back. relax. This will cause snore loudly enough possibly to yourself or others. Not that snoring paniment of slumber. is a sure sign of deep, can avoid snoring, however, quite as much muscular relaxation ] muscies you is an evil restful sleep. position I have mentioned. of the very likely ways of causing the morning ‘‘tired feeling’ to disappear. i.e DES muscular relaxation, the other prime requisite for sleep is monotony. Excitement prevents slumber and causes bad dreams. Indeed, the excitement that usually accompanies evening gatherings probably tribute to something they have before going to bed. The be attributed to their stence., The best way to obtain ‘p in a quiet room. absolutely essential to monotony. larly repeated sounds, cessant ticking of a clock, can exi monotony Slee such the are as ous. They are good instigators of sleep after you become accustomed to them. The muffled ticking of a watch under- neath your pillow will help you to sleep. tend to You can learn to sleep in a and find the constant up- Extraordinary sounds, though, awaken you. boiler factory roar conducive to sleep. 3ut a com- paratively slight noise—the passing of trolley car or an automobile, or the foot- step of some one near your bedside raises your blood pressure immediately and is likely to awaken you if you are not sleeping deeply. The next most important considera- tion in seeking deep, fort. A soft, comfortable bed, a comfortable pillow to raise your head and prevent the blood from rushing to your brain, and covers that are sufficiently warm without being too heavy are essen- A hard bed, a lumpy cause are tial to sound sleep. mattress, heavy covers uneven pressure on the body. They irritants, and tend to make sleep light. or very \ YITH these aids—muscular relaxa- tion, monotony, and comfort—you soon can teach yourself to sleep deeply, very quickly. Within a short time you will find that six hours’ sleep is enough for you. During my recent investigation re } of sleep leep properly ar hours of You cannot, mind toda to get along with six hours’ sleep, put that schedule into effect You would find that harmful, sleeping. however, make up work. (Continued on page 147) such complete relaxation be obtained In this posture, gravity will cause your lower jaw to drop and your mouth to open when your jaw to awaken accom- On the contrary, it You and still get and quite as much rest if you will sleep in the This is one is the cause of the nightmares that most people at- -aten deep sleep of old people and people who live in the country monotonous is to Yet quiet is not Regu- in- monoton- restful sleep is com- soft, I taught many persons how to nd how to cut down their your y that hereafter you are going and tonight. especially with regard to your ability to do mental

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Page 147

POPULAR SCIENCE MONTHLY Do You Sleep Too Much? (Continued from page 140) In one of my experiments I found that persons who have lost two hours’ sleep are unable to work as well on the follow- ing day. The reason for this is that they are forced to use more than their ac- customed amount of energy in accom- plishing any of their usual tasks. With the loss of a whole night’s sleep mental efficiency is lowered by as much as 25 per cent. In fact, doing without sleep is more dangerous than doing without food. A | dog can be starved for 20 days. It will | lose weight, but will recover rapidly when | fed again. To deprive a dog of sleep for five days, is fatal. With men virtually the same thing holds true. ROFESSOR G. T. W. Patrick, of the University of Iowa, not long ago kept three men awake for 90 consecutive hours—virtually four days. At intervals he gave them psychological tests to measure their working efficiency in various mental functions. Their mem- ories were affected particularly. After 72 hours without sleep it took one man 20 minutes to commit to memory a selec- tion similar to one which he had memor- ized in a little more than 2 minutes before losing sleep. After 86 hours, he could not memorize at all! Another man began to “‘see things”’ colored insects which he tried to kill. All of the men suffered immeasurably. However, you need not be afraid that something like this will happen to you if you learn to dispense with two or three hours’ sleep a night by learning to sleep deeply. The subjects I used in my in- vestigation all were accustomed toeight to nine hours’ sleep a night. Now they get six. They discover that the shorter sleep- ing time not only is giving them more time for work or play, but actually has increased both their mental and physical efficiency. This is not guesswork. Scientific tests of the body metabolism and men- tal efficiency that each man _ under- | went before breakfast during the in- vestigation show that this increase in efficiency undoubtedly has taken place. If you are going to cut down your sleeping time, make the reduction from | the night end of the sleep period. That | is, stay up later and rise at your usual time. When this is done, the deeper sleep that you get when you go to bed seems to compensate for what you have lost. Remember—it is not how much sleep you get that counts; it is the kind of sleep. Are you getting enough of the right kind? Or do you get too much poor sleep? ID you know that one out of every 10 persons in the world suffers from defective hearing of some sort? | How well do you hear? Perhaps you are | partially deaf and don’t know it. | In an article next month a dis- | tinguished expert will tell you how to | test your hearing, and how to safeguard | yourself from the tragedy of living in | eternal silence. | Seventy-eight Years of Practice HE firm of Munn & Company filed its first application for a patent in 1846, and for seventy-eight years has endeavored to keep pace with the inventive genius of the United States. An experience of many years is at your disposal. If you have an invention which you wish to patent, send your sketches or model together with a description of your device, explaining its operation, and you will receive prompt, courteous attention. Write for our Handbook on PATENTS A full and complete booklet on Patents, Designs, Trade-Marks, Foreign Patents, Copyrights, Labels and Patent Office Practice with an explanation about our methods, terms, etc. All communications strictly confidential Keepin touch with the inventions of the world by reading ~ SCIENTIFIC AMERICAN The MONTHLY MAGAZINE with a special appeal to every man of inventive genius. Recent rulings of the Patent Office, descriptions of the latest patented inventions, legislation and court decisions affecting patents, are noted in this authoritative publication. MUNN & COMPANY Patent Attorneys 683 Woolworth Building, New York City Scientific American Bldg., Washington, D. C. Tower Building, Chicago, Ill. Hobart Bldg., 582 Market St., San Francisco, Cal. Van Nuys Building, Los Angeles, Cal. NVENTORS your ‘peas Send for our Guide Book, HOW TO GET A PATENT, and Evidence of Invention Blank, sent Free on request. Tells our terms, methods, etc. Send model or sketch and des ription of your invention for our Examina- -—-- ----------------- ----------- tion and Instructions without |.) ' Nam charge. i RANDOLPH & CO.: °°" Dept. 130, Washington, D.C. | crv STAT! '

Page 148

hat I Learned | About O > } “ ee.

By Byram C. Kelley, A.M.,L.L.D. a ) n consti ( st star a iI al | ive eCVveé { ed | 0 \ irs ¢ ly

wonder Sor yn beg n

‘ ( le pep vt es S und resis 1 s{ I V re | A s< I he Sl hiex to ( SS ( S wh Ce is so | ey n n past 40. Then through l friend, | de t!] cquaint: ince I bet ol Am ican \ssocia r the Advancement of Science, who I 1g to light ost inter- esting facts about the peculiar conditions Why Many Men Are Old at 40 Have Gland Trouble Common Middle Age Ailments 10,000 Men Find Relief

All Explained in FREE Book rit ail request t aR: Rasen Manatee Cow pany, 4038 Main St + Fiera ami wee Ohio, t istrib Itir t t 1ut r W ern office, Dept. nC. “ped Angeles, Calif. POPULAR SCIENCE MONTHLY A New Era in Auto Construc tion Ase ri ei a record of eve rythin g op does to the ec: y turn of a wrench or down. If during this in the 1 the road—every screwdriver is put interval repairs are garage, a detailed record “Then at the completion of 25,000 miles of this strenuous pace, in about three months, the car is taken down and mea- surements and tests made to determine the wear of parts, the fatigue of metals, and other scientific data. In this work e) necessary is kept. the most exact instruments and devices are employed. Then from this informa- tion we set to work to improve. or strengthen the parts that show the need. HESE cars sometimes carry sand- bags equivalent to the weight of four or five passengers. In road-testing a five- truck, it is loaded with six or tons of gravel and otherwise subjected to extreme conditions. A scientific de determines the fatigue limits of metals. Like a piece of pasteboard, metal wil give take within its limits, but eventually will break.”’ I had the rather freezing pleasure of stepping out of a Dayton summertime into a temperature 20 degrees below zero, which experiments were being made with the performance of retors, lf-starters and ignition The refrigeration room is big enough to hold an automobile, and when the losed and the recording devices out- the results can be watched ton seven PviICe and elastic g carbu S¢ systems. big doors re c side ( onnected,

comfort. Motor-cars must be made to run in winter, so all designs must be checked for temperature. in, on my own responsibility, it seems not too much to predict that some we may have a carburetor that can start an engine smooth ly and quickly ir he coldest weather. There another kind of science that played a tremendous part the development of the automobile industry. This is the science of the mechanical engineer, supplemented by the achieve- ments of the production engines [ p to 1910, automobile were made under mechanical conditions that were rimitive as we now see them Hol were bored one by one, men wit rd hand rewdrivers and wrenches, and 10 or 12 husky laborers were used to peram- ulate an automobile body to an elevator. ODAY the multiple drill scoops out

dozens of holes from four directions at the same time. The power screw- “pe } . : 3 1 driver completes in a few seconds what hand power required a minute or two to accomplish, while another device faster 4 , 4 7 18 or more nuts a* one twirl. And now mighty cranes and other conveying mechanisms take over th work ‘of hundreds of men. One suc} ta ig under the steel rafters of the factory roof, actually moves four directions’ at the same time, re ing out with ics various arms like a giant octopus. down and takes out a carload of steel at motion machine, travelir in } one gContinued on page 149) -ach= The great lifting magnet reaches Registered Patent Attorneys Nc’ in U. S. and Canada

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— ee » casi A New Era in Auto Construction (Continued from page 148) Monster presses come down on sheets | | of metal and—presto!—a whole fender is made. One of these great presses, | operated by two men, does the work formerly accomplished by 40. A steam hammer with a 7000-pound blow elimi- nates the labor of dozens of blacksmiths. It was once the custom to assemble automobiles by gathering the parts and setting them up as a child stirs up his box of blocks and builds a house. One of the most sweeping changes in auto- mobile production was wrought when the present method of assembling under motion came in. The automobile grows as it moves slowly through the factory on a traveling rack that runs on rails. Certain parts must be attached when the car reaches specified stations on the route. Every man has prescribed work to do. If greater production is required, the speed of the traveling rack is increased and | more men put on. THOUSAND men _ now produce three or four times the cars they did. In some operations months are actually crowded into days. ‘‘Here in Dayton,’ Mr. Kettering said, ‘‘we use the most exact instruments for experimenting with the physical properties of metals. We can take almost any piece of steel and pull it apart as you might stretch and break a rubber band; an instrument measures and records the pulling power required, be it 200 or 200,000 pounds. “‘We determine the hardness of steel by dropping upon it from a predetermined height a very hard steel ball. We caleulat the resistance by the rebound. N another room of our laboratories we conduct microscopical studies of stee] The internal structure tells us many things pertaining to strength, hardness, and all the qualities necessary to th particular uses. The microscope may ré veal overheating in forging, for instance or impurities. ‘““We make microphotographs of the | | inside of the metal. showing the molecular formations magnified hundreds of times. | “There are many wonderful instru- ments for checking the accuracy of | ammeters and speedometers, determining | the horsepower of engines, and getting other scientific data. “But don’t forget that the machine we are experimenting with is already mar- velous beyond conception. For instance, | the engines of some ears fire 16,000 shots a minute, while the most rapid firing gun fires less than 1250. Every one of | these 16,000 explosions is caused by a | spark delivered on schedule time. ‘“‘This is the wonderful machine we are seeking to improve.” HIS is the second of a series of for- | ward-looking articles by Mr. Wool- | ley on what science is doing for modern industry. The third will appear in an | early issue. POPULAR SCIENCE MONTHLY Charge ’em overnight Ce With Sprague BX Cable it is easy for your contractor to wire the garage for electricity. Then you take the Tungar to the motor Car battery. How to plan complete wiring in your home told in the new fully illustrated book, “‘The Home of a Hundred Comforts”—the book that thousands have sentfor. Write today for your free copy. Address Section PS 10 Mercl wand Department General Electric Company Bridgeport, Conn. The handiest electric outlet at home is the place to recharge your radio or auto storage battery. All you need is a Tungar Battery Charger. It will ‘‘charge ’em overnight.” The Tungar for home use embodies the same safe principle as your garage man’s larger Tungar. With a completely wired home you attach Tungar anywhere without disturbing lamps. Sold by Electrical, Auto-accessory and Radio dealers. ange _(BATTE RY CHARG ER) s on iternatir GENERAL ELECTRIC ing which provides preparation For Cuts and ices gi uat re inst it ne rapid promotion of ie those who demand all else, a sat >} Atalldruggists’, $1.2 postpaid a ( zig ) rae Liberal trial bottle, 4 W. F. YOUNG, : 350 Lyman St. Springfield,Mass. a postpaid EAT Without Coal a 30 DAY FREE TRIAL a For esis te Sore Throat, Mouth Wash, Strains, Rheumatism 3 — Internat ional He ating Co. ¥ y he ) Deets 30-J ,117S.14thnSt.,St.Louis,Mo re 4y Agents: .” We pay $60a ee Write * for e Sample Off

Page 150

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Factory connections in both East and West. We ship from ae point. Don’t consider buying any furnace until you find out about the Bu! T tony Write now — before you forget! Fits Any Floor Height No matter what the de or cellar may be — the Bulldog fits it. The adjustable casing (another common sense feature) takes care of this. Write at once for our offer and our free catalog together with the wonderful record of Bulldog success. Mail this coupon Today. Saaceseeee Babson Bros. Seeeeeeese pth of your basement 19th and California Ave., Dept. 13-67 Chicago Without obligating me in any way, please send me your free catalog and special offer on the Bulldog Pipeless Furnace . = Name .---------------—-—-—---—— es a E Address snceanangil POPULAR SCIENCE MONTHLY Why Animals Understand (Continued from page 51) Quicl contract the throat and inhale with same whistling squeak with which you began. Repeat this four times and you have the complete salutation of the zebra when he “‘he-haws.”’ The domesticated ‘“‘*haw-he, haw-he, haw- long sound of “Shaw” in exhalation first and whistles with his contracted throat each time he inhales between ‘‘haws.”’ In imitating the bray of either the donkey or zebra, the prolonged sound upon exhala- tion should be given a slight nasal quality. * you find monkeys amusing, you will enjoy being able to chat with them in their own ‘“‘dialect.’’ In addressing monkeys or apes, friendly sounds must be accompanied by appropriate facial ex- pressions. Give a_ guttural staccato grunt, open your eyes wide, raise your eyebrows and protrude your lips, making a clucking, kissing sound. If Mr. Monk responds by raising his eyebrows and then lowering them in a frown, you may just as well drop the conversation, because he is in a surly mood and it is useless to coax. After you gain confidence in your ability to make animals answer you, you will probably want to make the lion roar. Breathe in as much air as your diaphragm will permit. With contracted throat give the sound of ‘‘ou” as in “you.”’ Prolong this in imitation of the long growl of the lion, as if you werein pain. Then suddenly open the throat and rattle the palate. An ordinary lamp chimney, used as a mega- phone, will give volume to your “roar.” The pigeon is one of the most affection- donkey really says he.’’ He gives the ate of birds and learning to imitate its ‘coo’ will give you many new bird friends. The sound of ‘“oot,’’ as in “root is the primary sound in the pigeon’s call. Give a long ‘oo’ then shove the tongue forward, quickly, be- tween the teeth until it touches the lips. This cuts off the air, producing the sound a ae?” oe this several times. to form the lips in an oval shape and make decom sound with the of the ue you make the sound; complete the call with the forward motion of the tongue. Repeat this dozen es, then fill your pockets full of cracked n and go out and calla flock of pigeons 1d see what happens. Familiar to all bird lovers is the the Listen carefully to his whistle. You imitate him by curving the tongue up in the palate back of the teeth Now, tT! rv a b ac k tor as oo a call of robin. can and whistling with an exhalation as in “he ha ha.” i Heer crow is justly known as a wise old bird. His ‘“‘caw’’ is not pretty, but you will find it easy to imitate and very responsive. When you call a flock is sure to come, so take refreshments enough and you will find them an entertaining company. By the time you have perfected the bird and animal sounds I have described, you will find many new suggestions in the fields and woods, the park and the zoo. When you begin to speak their ‘“‘lan- guages,”’ you will find innumerable shy crow, a for all creatures ready to be friends with you. Beautiful Rocker , Lamps, Sil- Save big money at our Pay as little up to Get all your Furnishings Thousands buying this new way. Big Catalog FREE Over 1000 other bargains, ver, China, Blankets Factory-to-Family prices. a year and a half to pay balance. at once—pay as you use. Furniture, Rugs ,otoves,etc. as $3 down; New Fall “Larkin Book of Better — sid Shows oe ing for parlor, dining-room bedroom, kitchen axcaie Prices on famous Symphonola Phonographs Also Symphonic Pianos, Pl ayer Pianos in genuine Mg ahogany, Wal- n umed Oak. Pres trial. Up to 4 y 5to pay. Satisfaction or money back “k below artic le interested in, () Home Furnishings () Pianos or Players [) Phonographs ——}Cut out thisadv.—write TO-DAY for FREE Book. Lttkhitt Co tac. Dept. 1040, BUFFALO, N. Y. Peoria, Ill. Chicago, lil | Pulls Hills in High Saves Gallons of Gas ———— Mr. W. W. Henderson, a Kansas City mechanic, las perfected an amazin ivention that goes on the carbur fa car. Three minutes to take on or ff i mechanical work to do. But chan rmance of your car. Not only runs more power, less carbon, but deliv- ers “d mileage. AGENTS WANTED. Mr. ints to send one driver in each local ing vaporizer to try on his own car. See f how fine it works and how easy to lrive around in ir spare time and pick up $80 to $100 a week No capital, mechanical skill or sales experience “ded. Just send name today. W. W. HE NDI RSON Pres., SAFETY MFG. CO., 1815 WALNUT ST., KANSAS CITY, MO. “DON’T SHOUT” “T hear you. well as anybody. I can hear now as *HOW?' With THE MORLEY PHONE. I've a pair in my ears now, but they are invisible. I would not know had themin, myself, only that I hear all right.”’ The Morley Phone for the DEAF is to the ears what glasses are to the eyes. Invisible, comfortable, weight less and harmless. Anyone can adjust it. Over one hundred thoo- sand sold. Write for booklet and testimonials THE MORLEY CO., Dept. 797, 10S. 18th Street, Philadelphia Saws Logs — Falls Trees — » Buzzes Branches —Does Belt Work 6-YearGuar- entes — Cash orEasy Terms. \ Saws15CordsaDay! —Easy with the OTTAWA Log Saw! Wood sel- ling for $3a cord brings owner $45 a day. Use 4H. P. Engine for other work. hee! mounted--easy to move. Saws faster than 10 men. Ship from facto y or near- est of 10 Branch houses. Write for FREE Book today. OTTAWA MANUFACTURING CO. 1801-U Wood Street Ottawa, Kansas Room 1801-U Magee Bidg., Pittsburgh, Pa. Big Value for 10 Cts. 6 Song word ind music; 28 Pik tures Pre Gin ; 40 Ways to Make Mone i Borge 00k; 1 Book on Love 1 Magic Book 1 Book Letter Writ- ing; 1 Dream Book and _ Fortune Teller 1 Cook Book; 1 Base Ball Book le for games; oy Maker »%k, Language of Flowers; 1 Mor lelegraph Alphabet; 12 Chemical Experiments; Magic Age Table Great North Pole Game 100 Conundrums; 3 Puzzles; 12 Games; 30 Verses for Autograph Albums All the above by mail for 10 cts. and 2 cts. postage. ROYAL SALES CO,,. Desk 937, Norwalk, Conn.

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The Most Accurate Man (Continued from page 45) measurement comes into play in making each individual part of the gage precise to the ten-thousandth. For example, if a part is iri d witha length of 2.0165 inches, the rules of stan- dardization insist that it must not be 2.0168 or 2.0162, but as closely as possible to 2.0165. Modern with a tolerance as two ten- thousandths. That, for instance, was the tolerance allowed in the vital parts of the Liberty motor for airplanes. By the use of the Hoke gages it is pos- sible to make parts with this precision and to be sure that they will fit precisely into mechanism of the most complicated and delicate character. Naturally I was curious to learn where this master of accuracy found his starting point for his method of hair-splitting. “When the war broke out,’ he told me, “Il had been working for 10 years my notions of the new standards. Blocks of great accuracy had been made in Sweden, but the methods had been kept secret. My first results were dis- couraging, but the experience stood me in good stead when I sought to demon- strate my method to the government at the outbreak of the war. The Bureau of Ordnance and the Bureau of Stan- dards became interested and the machinery is made close as on help me. Within two or three junk, for making gage blocks. days later we had turned out a blocks of one size. Tested by any instruments these were not but optical measurements by the of Standards showed them to identical size and accurate that amazed the experts. interferometer, a machine that rays for measurement, showed never before Cc -onceived inch.”’ set be ust e Oot an HE use of light rays for measurement gave rays by using one of his gage blocks and a piece glass ground to exact is a fascinating process. Hoke me an idea of the action of the of optical glass smoothness and uniformity thickness. He placed the highly bit of steel against the ] precise surface of glass and had me look down upon steel through the glass. I saw a rainbow a spectrum of parallel lines. not parallel—that there was a The distance between anothe ward one edge. green line and variation in the wideness of this space. exerting a wringing motion. blue, denoting perfect contact. growth of a life passion for accuracy. know that his | 15 minutes.” (Continued on page 152) latter gave me a place to work and a man to days we had rigged up a machine out of some old A few of known convincing, 3ureau of to a degree Tests with the light accuracy within millionths of polished the the This indicated that the surfaces of steel and glass were wedge- shaped space between them, widening to- one r, in the spectrum, represented ten-millionths of an inch of Hoke then applied the steel block more accurately against the face of the glass, by The colors disappeared and the metal became steely The Hoke precision gages are the out- In boyhood it was not enough for him to yalk to school took ‘‘12 or He figured it in seconds and

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Page 152

152 He takes his pipe 1800 miles | I t Chi | | | ieincciascei | ' . , } No, it isn’t i Sé S Wile ypvects to nis | smo gy in the hous¢ We d t WwW hat he has a wife, f nat matte Mr. Mellor takes his pipe far into the erior e Land of Confu ' t ittac ) I ie od I : whic! among other waters, Salis tne upper Yangtse Kiang. This is what Mr. Mellor writes: } USS 1 | ( 4 | 1.1924 | x R ‘ 4 i lan n ] t t te tl i! ti i us | L Cat t I t f-the-way | nok We . t bh ] | | See ; | | ( } } f | ¢ a . t . se t \ 2 you would try Oo pu le us you free samples Edgeworth and chance to rst hand ) ma mok- ce 10. Writ oul name 1 ad- ares » Larus & Brother Compat 59 South 2\st Street, Ri mond, Va Edgeworth is id in various izes tos tne eeds d mé r rs. Both Edgewortl Plug Slice d Ready-Rubbed are packed in sn eke packages, in hand- some nun iors a pound A 1 ilso in several handy vetween size We ye gratetui for f ame and ad- ( of lr tobat ) hs r too f ou ( to them To Retail Tobacco Merchant If your j pper 1 yt up rly you witl I dge - worth, Lar & Brother Company will gladly send you pre paid DY parcel post a one- or two-dozen carton of any size of Edgeworth Plug Slice or Ready-Rubbed for the same price you would pay the jobber. POPULAR SCIENCE MONTHLY The Most Accurate Man (Continued 1 from page 151) trained himself to cover the distance in exactly the same time, to the second, each day ° The boyish passion for accuracy caused him to know that his fishing line measured five yards, some inches and certain sixty-fourths—I that degree member \ HEN he took the family sewing- machine apart, the boy of 11 first made a diagram with pencil on a sheet of wrapping-paper, showing the outfit as it stood. Spreading this paper on the floor, he deposited each part, as removed, on the spot corresponding to the proper place in the works of the machine. To prevent the screws from rolling, he stuck them through holes in the paper. In this way he succeeded in putting the machine together again without one part omitted. He was always timing something. Ifa train were 43 seconds late, he would com- ment on the fact. If the morning school- bell rang five seconds ahead of time, he knew it and secretly rebelled. Today he is looked upon by his fellow members of the Baltimore Yacht Club as a necessary evil; necessary in that his timing of races is the official standard of accuracy; and an evil in that he has a habit of showing that the boat reputed to sail 15 miles an hour never exceeds 1234 “Measurement is the fundamental of manufacture,” he told me. ‘‘The use of precision gages has made possible me- chanical operations that formerly were out of reach. Swiss watches formerly ere made by hand. Today they can be turned out by machinery with greatly increased accuracy. Particular people used to insist on hand-sewed Man- ufacturing precision now makes it possible to turn out millions of shoes that are bet- an the individual hand-sewed type. have not yet arrived of accuracy where I can re- the exact measurement he gave. Ww shoes. ter th “AS matic A result of precision we now are able to produce new forms of auto- machinery. The unskilled work- man is able to produce things once pos- sible only to those of the highest skill. T oday the skilled mechanic is needed only the production of the machine by accurate parts are made. The killed mechanic can do the rest. “The new accuracy in parts has revo- lutionized every of mechanics. Human life is safer because accuracy in the parts of an automobile prevents dis- asters that would from a lack of precision. Money is saved in vast volume because of the new possibilities in quan- tity production. By precision, the life of a machine lengthened in that spotty resulting from unevenness, eliminated.” 8) which he phase result is wear, is wholly TATURALLY I wondered if tended to elaborate his a millionth of an inch. “For the present,” he told measurements are far ahead of the re- quirements. It is easily possible, how- ever, to carry them as far as we please. When finer measurements are needed, we'll have them.”’ Hoke in- 4 gages to less than me, “‘the A Universal Kit Kellogg Radio Kit—— For Your Favorite peeneny HAT contains everything complete for assembling two stages of audio frequency amplification. The panel is drilled for three tuning units, which together with this No. 501 Kit will com- plete a radio set using your favorite hook- up, or most any other that you may desire to try. It is easy to “Butld your own” with this Kellogg No. 501 Radio Kit. Every part guaranteed. At vour dealers for $43.00. Use—Is The Test © Kellogg Switchboard & Supply Co. 1066 W. Adams St., Chicago, Ul. on Gallon of Gasoline ith Ai J e We guarantee nM HOT cars bar HOT present mileage, power and flexibility. Models for any car, truck, tractor, marine or stationary engine. Makes old cars bet- ter than new. See our mileage guarantees. Ford. .34 mi, | Chevrolet, .32 mi. ] Dodge... .28 mi. Maxwell. _.30 mi. | Overland...32 mi. | Oakland. .24 mi. Mileage guarantee on any other car sent on — ou can SENT ON 30 DAY’S TRIAL aiive ans car in heaviest traffic without shifting gears. Starts off on high in any weather without priming or heating—No jerking king. Agents Wanted AIR-FRICTION CARBURETOR COMPANY 1287 Raymond Building or ch oe ede: ton, Wales and all standard make +s often at less than one-third regular price! All sizes and styles. A-1 condition. Rebuilt by experts. low as $5 down. Why pay big pri Hundreds of well-known firms models and bargain prices you money. Do it NOW. RELIABLE ADDING MACHINE CORPORATION 168 L W. 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Page 153

REDUCE mou TAXES Taxes are too high, and legislators are rather 3m ye finding ways to reduce taxes. Why watt for govern mental action? Cut a big slice from your taxes by spending a ibly less for coal and apply the saving to paying your taxes. It can be done ettectively. Yes—and you can get more heat than you need. Simply attach the inexpensive CROWN Fuel Saver to your furnace. This remark- able device will save you from 20 to 50% of what you ordinarily spend fer coal. There's no political bunk to this reduction for The CROWN Fuel Saver is GUARANTEED to make at least a 20% coal-saving or your money back. HEAT FROM PERFECT COMBUSTION (i The CROWN Fuel Saver fits the feed door of any heating plant. This scientifically- de signed device provides, by means of na- tural draft, the s f pre-heated necessary to burn -tl mo ke 1 ¢ that usually escape thru the chimney. See illustration.) This gives amazing results a slower fire, less ashes, more heat, and , steadier heat on the minimum of coal. If uu want real comfort this i r, aller coal-bills and less furnace worr Ww for with money-back guarantee. Cc. F. S. Co., 110 N. 10th St., Richmond, Ind. Distributors Wanted—Men who seek a solid business connection and a steady income, write giving details of past business experiences. details and special low price of CROWN, YOU 100 CAN PLAY THE TG knowledge of the psychophysiological | HAWAIIAN eh we ‘i effects of light and color entering our lives *¥ \ietin: deaiiaiaindachaals deal FT| through the doorway of vision. He rea cannot supply you send us™ JUST AS THE HAWAIIANS DOL-EP) PLAY ALL THE LATEST EAS ONLY MOTIONS used in ions \ the fascinating Hawaiian Gui- C= tar, Our native Hawaiian instruc- 40,000 students have learned The 52 printed less ¢ man y pic tures quickly. You how te ) ead note ical knowledge learn to play o y xind of music pay as you pla FREE “GUITA 2 we give this full size, high grade Send your name at once and let % tell you ail about the 52 easy less« Band the tree guitar. You have eve thing to gain. Don't put it off. cial offer and easy terms. Special courses on Vie- of Music, Inc. lin, Tenor-Banjo, Ban- jo-Ukulele and Ukulele Dept, 46, New York, N, Asa special offer to new stude 233 Broadway (Woolworth Bide. tors teach you to master them quickly. Pictures show how Kverything explained clearly. PLAY IN HALF HOUR After you get the 4 easy mo- tions, you can play harmonious chords with very little practice. to | play in this easy, pleasant way. PEASY LESSONS sary You nts in- atrument free of charge. It is sent atonce without red tape or delay. WRITE AT ONCE us ns ry A post card will do. Ask for new spe- First Hawaiian Conservatory POPULAR SCIENCE MONTHLY Lights Aid Happiness (Continued from page 57) atomic radiation exemplified by radium and its family. It is a fascinating picture. The atom of radium or of a relative, containing it ‘solar system’”’ of electronic bodies of almost infinite smallness, yields its energy | verhaps the source of all energy ’ ‘ne Th ionared — © erg It’s a Genuine Solder throughout stellar space—for the benefit of those who acquire knowledge of its | properties. How different we are from ‘ f 17 rac To | \ . man of only yester-century! Compara- : 7 ee. his Th um ncae Lost sat. | Simple to Use tively we know so much more; but actu- ally so little. Requires Only Heat \ YHAT countless millions have died 'Y through ignorance in past centuries! But what a pity they are still dying through prejudice, for even today there are persons who are jealous of the powers of radiant energy. Then there are also those ever-existent HOUSEWIVES A simple, practical mender quacks who pretend to know more than for metal ware in the home actually is known. Thus we find, as always, diligent scientific workers battling on one front against the cowardice of prejudice and on the other against the valor of i ignorance. In the field of colored light there is op- portunity for the honest and the dishonest, SCHOOL BOYS the scientist and the quack. A famous For mending and making royal prince was cured of smallpox with- a out pitting by keeping him under red light. Naturally the unthinking drew a positive conclusion to the effect that red light was efficacious. As a matter of fact, it was the absence of the other radiation and not the presence of red light that achieved the result. Darkness would have sufficed in this case as well as in the photographic darkroom, but red light is better because it has no influence either way and enables those present to see. Up to the present time we have little knowledge of the biological or physio- logical effects of colored lights on the human body. However, we do have some KESTER METAL MENDER HOMETINKERS Need will develop from roof to cellar MOTORISTS For repairs on the road of at home FARMERS For use in dairy, garage, household and emergency repairs SPORTSMEN Keep a can in your kit you'll have need for it again, we find the valor of ignorance doing business, but fortunately serious damage is confined to the purse of the unwary. | \ HILE scientists are unraveling th sean ow vlc, en tangled skein, all of us can utilize Gentlemen: Send me one can Kester Metal Mender for color to some extent by adding variety to | “MP! ®*°tBostpaia ‘any here in U. S.A the drabness of every-day life. The emo- | Name tive value of color is not as strong as that Address of music, but it is just asreal. A little mu- | City State sic daily is good for us, but we could not Dealer enjoy continuously a symphony concert ~ : ora Wagnerian opera. Soitis with color. Exposure to colorfulness each day is a bit of variety the effect of which is similar to music, and this effect is confined not merely to appreciation of the beautiful, but has a deeper influence upon our minds, our emotions, and consequently our health and happiness. RNEST BADE, Ph.D., who in pre- vious articles in POPULAR SCIENCE MONTHLY has given practical hints for $25.00 in Prizes See top of page 6 in front of book for full details | planting and caring for your garden, will tell in an early issue how to harvest your crop and store your products for | the winter. A PAT. 9913; 51.1% B 7-16-18 10-19-20 THE STEMCO ENGINEERING CO 201 Webb St., Dayton, Ohio

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M S. Cc H A | : C Ss’ ow Broadcasting HANDBOOK 330 PACES More than 300,000 sold Measures; Easily Under- stood Mathematics; ; Belting; Hydro-mechanics; S of Materials; Boiler Design; Care and In- Horsepower of Boil- ys; Exhaust Heating; Machine Horsepower of Engines; The Slide Valve; Rope Bel: ing; dhe “vsomeirs and Steam — of Boilers; 5: ‘He rward earned rr works oa hal f ti ime cand d made $100 sina he w mon ths on $100 Auto Gwner, Store and Fac “ce a at ive ; euaiaene i vetons er sold Fire Extinguishers before. you on road to success first day. » can show you_how to make big money No Experience Necessary. Get our new — ‘find out how to make TH HE FYR- FYTER CO., fpecial trais ing course starts y real money—write today! 404 Fyr-Fyter Bidg., Dayton, O. POPULAR SCIENCE MONTHLY Works (Continued from page 71) sounds made near by. The aerial, or “‘antenna,” is a long wire, one end of which is high in the air and the other con- nected with the ground. Over this the modulated radio waves pass to the ether. A detailed description of the trans- mitter cannot be attempted here. Suffice it to say that it is made up of coils of wire, metal plates, insulators, and glass bulbs its units are technically known as ‘vacuum tubes,” ‘‘inductances,” ‘‘con- densers,”’ ‘‘transformers,’’ and so on— arranged in such a way that electric cur- rent supplied by large generators near by flows back and forth through the coils very rapidly—-possibly a million times a second. This oscillating current is the ‘fcarrier wave’’ speed of vil to above. Its nd other remarkable due to the vacuum tubes transmitter, which are quite the most amazing things in radio referred ration a properties are in the VACUUM tube electric lamp. like a big Within it is a metal looks tube called the ‘“‘ plate,’”’ which surrounds another tube of wire gauze called the ‘grid.’”” Within the grid is a filament, just like a lamp filament. If an electric cur- rent is permitted to flow through it, this filament becomes white hot. From it then shoot millions of tiny charges of electricity called ‘‘ These form a sort of ‘*bridge’”’ the filament and the electrons.” between plate, over which a current of electricity may pass, but in one direction only. When an electric current of proper potential is applied to the grid—-which you will recall is between filament and late—the grid acts as a screen, prevent- ing the passage of from the fila- current plate. In the transmitter, are so connected that this nd flow’’ of current is the ment to a this os¢ Now, ee a muilion vibrating the trans- mitter, might be put on the air and picked up by a radio receiver. No could hear it, though, se the most sensitive human ear is incapable of detecting vibra- tions of a rate greater than about 8000 a Anyway, the vibration of the carrier wave is not nor music. Speech, music, ther sounds that make up ng’’ are transmitted by modulation carrier wave in this way ‘illating current, tim . } ° times a second 1n one becau second. speech and the ¢ ‘broadcastit of the HE performer sings, talks, or plays into a sound-sensitive instrument called a ‘*‘microphone.”’ This is much like the telephone instrument you talk into. When sound waves strike this instrument, part of it moves in unison with the sound vibrations. These movements cause corresponding variations in electric cur- rents passing from the microphone to the broadcasting transmitter. These are the currents used to modulate the carrier wave and thereby put the broadcasting program “‘on the air.” The currents as they issue from the microphone, however, are very feeble, and must be magnified greatly before they will affect the powerful carrier wave. (Continued on page 155) “LIGHTING FIXTURES” Ready to hang. Direct from the manufacturer. Completely wired including glassware. Send for Catalogue No. 26 (Just off the press) Specia! proposition to Dealers ERIE FIXTURE SUPPLY CO. Desk A. Erie, Pa. Motorcycle Bargains ot 2 ES SAVE 25% to 65% $ nm Slightly By S\ Used and Rebuilt i fotorcycles, Ace «4 N ~ycles, Ace, Indian, Excelsior, ® > Harley-Davidson, Cleveland, Side = Cars, Johnson Motor Wheels, Evans Send for ¥ i Power Cycles, Bicycles > | Free Bargain Bulletin and ay Saag Money Saving Message, listing ae - hundreds of bargains supplies, ere et MERIC AN MOTOR CYCLE CO. 2047 W. Chicago Ave. CHICAG Oo Squab Book FREE Squabs selling at st prices ever known. Greatest market Pa ope Make mo breeding them. Raised ir month. ship everywhere our famous breeding and supplies. tablished 23 years Write now for big illustrated free book, oney Breeding Squabs in used, rebuilt and new machines Dept. 1028 We stock one How to Make I PLYMOUTH ROCK SQUAB CO. 616 H St., Melrose Highlands, Mass, Fifth Avenue, New York Custom Tail- ors Want acents tosell advertised brand al wool tailored to measure suits and overcoats direct Lowest prices in America. Sell! or No capital or experience required. Big line swatch samples Free. Biggest Commissions eee daily Fermanent positions. $75 to $100 weekly o Free to agents onneo’ TaHOrnes Co., | 100 Fifth Ave. «Devt. L-2. New York. FORD ‘x72 THIS MAKE YOUR Other types down to $3.50. Famous sure fit, Roth life- $ a. ize patterns and picture instructions show how ou i easily convert your Ford into this fa: aucy Sport Ca as bundreds have done with a few dol ~ material from the hardware store. No ee an fe 's Pres ssed een, Classy etal Streamline ° Rear only $6.40 de up to- the-Minute ~~ livered. Built ae rides wonderfully « e pany. Order NOW wt while we can make good delivery a ne in for illustrated prospectus of Sport Baltes, Jifdanu’’ i (Josum Windshields KUEMPEL. co. 534 Ke compel Bidg., Guttenberg, lowa Ford Runs 57 Mileson Gallon of Gasoline \ new automatic ar ilating device been inve ohn A. Stt ky, 3679 Fourt S Pukwa kota, with which autom« biles have 5 ona f ine carb pre I par pl t It can be installe by ti Mr nsky want da ple at I Owl > him today Adv. AGENTS 500% PROFIT GENUINE GOLD LEAF LETTERS Guaranteed to nevertarnish. Any put them on st« Enormous demar res and office win s. id, large profits, Paul Clark r says: smallest day $28.70. R.L. Reel mad $920 in two months. Write today for free sample and liberal offer to general agent METALLIC LETTER co. BUCHSTEIN’S FIBRE LIMB soothing to your stump— strong, cool, neat, light Easy payments. 433A N. Clark Street, Chicago Braces for all deformities Guaranteed 5 Years Send for Catalog Today P. BUCHSTEI N C O., 610- aed Ave., So. Minneapolis, Minn. AR GRAF ‘otect your tools from theft. Write, nay name, engrave any design on tools and metal with electricity =~ writing on paper with en or pe * Complete outfit 3.50, orapeia anywhere Interest- ing descriptive circulars free. Write to-day. Agents wanted Arkograt Pen Co., 1171-A East Stark St., Portland, Oregon)

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How Broadcasting Works (Continued from page 154) This magnification is accomplished by means of vacuum tubes in a amplifier.” The magnified current, reaching the transmitter, causes the carrier wave to vary in exact accordance with the speech or music waves striking the microphone. This modulated current is carried to the aerial, and the program of the broadcasting station travels at the speed of light—186,000 miles a second — to radio listeners at all points of the com- pass. In up-to-date broadcasting studios, the program delivered before the microphone is not carried directly to the transmitter, but passes through apparatus in a control room, where an operator checks the quality of the broadcasting. A similar check is kept by the ope- rator at the transmitter, and in this watchfulness lies the explanation of the uniformly good quality of the programs of the larger broadcasting stations. “speech ANY of the programs broadcast, of course, are performed outside the studio—in theaters, hotel dining-rooms, lecture halls, baseball parks, and similar places. In these cases the microphone is removed from the studio to the where the event to be broadcast is taking scene place, then connected with the broad- casting station over ordinary telephone lines. When the radio waves carrying speech or music encounter an aerial, they set up in that wire currents that correspond to the vibrations of the radio waves. Your receiving set picks up those currents and transforms them into audible sounds by a process that will be explained in a later article. The next time you use your radio set, try to visualize these various processes of broadcasting as the programs sound in your head phones. You will probably find your enjoyment of radio greatly en- hanced thereby, and a knowledge of these few fundamental facts regarding radio will supply you with the groundwork upon which to build a really expert knowledge of this marvelous new art. EXT month's article will carry the story of radio waves from the aerial of the broadcasting station to the head phones or loudspeaker of your receiver. Recent Publications Shanks’ Mare, by Charles Coleman Stoddard. Sets forth the recreational value as well as the charm of walking in city or country, with practical hints on how to dress for all kinds of weather. George H. Doran Company. ZR Wins, by Lieutenant-Commander Fitzhugh Green, U.S.N. A thrilling novel of adventure in the Far North, describing an airship voyage to the ‘‘Lost Polar Continent,”’ of which Commander Green wrote recently in POPULAR SCIENCE MONTHLY. D. Appleton & Co. Making of Man, by Sir Oliver Lodge, F.R.S. A study in evolution. George H. Doran Company. The Common Sense of Health, by Stanley M. Rinehart, M.D. George H. Doran Company. POPULAR SCIENCE MONTHLY i New Self-Massagin¢ Belt Reduces Waist—Easily! Produces same results as an expert masseur, but far quicker, easier and less expensive. } Substitutes good, solid, normal tissue for le. that bulky, useless disfiguring fat, yet does fs it so gently that you hardly know it is there nastics oT Formerly those who vy | dieting or strenuous exer had fessional masseur H { ectiv : lodged the fat and brought about the desired reduction But it wa exper VC ind tim suming, and But now a w lerf ‘- new invention bri thi same effect met d vithis the reach of ll rhe Weil Scientific Reducir Belt uses this same sage principle tin ) ‘ of its specially pre pared and scient lly fitted rubber It ) con lt t, every b t u take ve ke " cons er t eV incl f ttl abd W kir 1 t \ evel 1d day ight, it i m > rap t I yrdina massage, saving both time nd m Actually Removes Fa It does not merely draw in your waist and 1 you appear thinner. It actually take f ew weeks \y find 4to 6 I r waistl \t 1e t disord constipat backacl t breat lisappear t “1 t put back in 1 I Pp M \ filled with a wondert Vv ¢ b and feel 10 to 15 yea unger, rhe Weil Belt i ed by hundreds of prof nal hl 3 an ke I | { 1 but t t trength. Hi f I ciple b Pp r e 5 lar f b it Wr 1 at I i Op IX I P Ort ) rT it M c t iy t THE WEIL COMPANY 1010 Hill Street, New Haven, Conn. $25. 00 in PRIZES SEND FOR THE INTERNATIONAL CATALOG Se te net pr ky auto and acce ries for F 4 st W Price a buying Dir n FOR FORD-—Prices from $27.85 up. consumer direct—Pay only One Profit Ponsa to International Body Works, TIRES WITH 500 NAIL HOLES LEAK NO AiR A new puncture-proof inner tube has been i by a Mr. M. E. Milburn of Chicago. In actual test it was punctured 500 times without the loss of air This wonderful new tube increases mileage from 10,000 to 12,000 miles and eliminates changing tires. It costs no more than the ordinary tube. Mr. Mil burn wants them introduced everywhere and is n ing a special offer to agents. Write Sales Manager L. R. Hansen, 336 West 47th St., Chicago. 914 W. Ohio St., Dept. 8. Chicago, III nvented See top of page 6 of this _ issue for full details. DRESS UP $3. 8S YOUR CAR CUSTOM MADE peegeni dies Maxwe Writet LIBERTY TOP & TIRECO., Dept. E-3 Cincinnati, Ohi HAVE You AN INVENTION? Protect and Profit From Your Ideas “WHAT TO INVENT” Suggestions to Inventor WORLD PROGRESS PUB. CO., INC. Room 202 Victor Bida. Washington, D. C. REE rai. B sport. powerful lenses. _aeroplane 4 miles away.’’—Mrs. as clear as if in front °o Clyde Scribner. R E E watchin submarines handsome, sturdy miles otf the coast.’ 12 in. leatherette ——_ Grosh. Can Carrying Case} Sisying in sent FREE with| school P Wonder Tele- “4 scope for short See people and objects miles away, on land or sea, as if they were close, Wonder Telescope gives new pleasures to home, See moon and stars as never before, long, in5 sections; measures 12 inches closed; Thousands pleased—*‘Could tell color of Yarbrough - Provincetown Light, 23 mies away, have been P neighborhood; entertain your friends, send only name and address for telescope and ease by parcel post. 5 On arrival deposit with Postman only $1.85 plus a few pennies postage. Satisfaction guaranteed or money refunded. Order today While supply lasts. farm, camp, travel, Opens out over 3 feet ; Brass bound; has ‘Saw nis gf the pu mbers on freight ¢ rarer away, see mountains on moon a. G. & — Because of fortunate purchase fro ym a Eur maker we can give you a big bargain. Be st in your ‘eae no money; 7 ton.

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« POPULAR SCIENCE MONTHLY | ogue A Valuable 68-Page Reference Book on Radio—a Market Place for the Best in Sets and Parts We want you to have a copy of Ward’s new Radio Catalogue. You will find it to be an encyclopedia of information on Radio, the livest topic of the day. It con- tains a new Radio map—diagrams of the best hook-ups—descriptions of complete sets, and standard parts for building sets. Headquarters for Radio Montgomery Ward offers you all types ESTABLISHED 1872 Montgomery of Radio Equipment at a saving. We sell direct to you only merchandise of high est quality. Everything you buy from us, carries our 52-year-old guarantee—‘“* Your money back if you are not satisfied.”’ Enjoy the Long Winter Evenings Every form of entertainment can be brought into your home by Radio. Keep in touch with the world—Sports—Elec- tion Returns—Dance Music—Speeches —Sermons—Current Events—you can enjoy them all by Radio. Write today for your copy of this com- plete Radio Catalogue. Address our house nearest you: Dept. 5-R. Ward &Co The Oldest Mail Order House is Today the Most Progressive Chicago Kansas City St. Paul Portland, Ore Oakland, Cal. Ft. Worth ‘Stop LEAKs! REPAIR BREAKS! MAKE Loose Parts Stay TIGHT! Smooth-On No. I SMOOTH-ON et re REPAIR SMOOTH-ON MFG. CO. BOOK Dept. 58 574 Communipaw Ave. Jersey City, N, J. SSPECIAL INTRODUCTORY PRICE a limited time only, and to introduce this w and superior St ‘B”’ Radio Battery t t Public, we are selling it for $4.00, Regular Retail Price is $6.00. You sz $2.00 by orderings NOW. We believe there is no better battery than the World Storage “B” Battery (12 CELLS—24 VOLTS To ten million homes 3 lions of o§ and to countless mi! rs—this WORLD Storage ** sat ngs @ new conc ion of battery economy and perforr ance Here is a battery that pays for itself ina few week will last for years and can be recharged at a negligible cost And you save $2.00 by ordering now. * Equipped With A Superior Battery sclia Robber Case Hee basye duty 21-8in. x lin. x 1-4 in. plates and plenty of a y acid circulation. Ext y glass jars allow ready observa of charge and j les It holds its charge, v akage and seepage of current You will find this , while idle, at constant voitage yattery a boon to long distance receptio t does away with a great many noises so often blamed on **static.’’ Mail your order today. SEND NO MONEY Just state number of batteries wanted and we will ship day order is received. EXTRA OFFER: 4 batteries in series (96 volts), $15.00. Pay Expressman after examining batteries. 5 er cent discount for cash in full with order. Send your order OW and save $2.00. WORLD BATTERY COMPANY Makers of the famous World Radio **A’’ Storage Battery 1219 S. Wabash Ave., Dept. 80, Chicago, IIL SAVE $2.00 BY ORDERING NOW! = ; ‘ ; . | Keeping Your Car Free of Carbon (Continued from page 83) there are no loose, badly fitting, or broken piston rings. Next, see that your oil sup- ply correct. There should be just enough—every car has a gage that makes it simple to determine that—and it should be of the right quality. Next, make sure that the carburetor is adjusted correctly. A too rich mixture is about the quickest and surest way of clog- ging your cylinders with carbon. As a last measure, take care how you drive. Long trips and steady driving with an even, economical feeding of gas, will not cause carbon to form in excessive quantities if the motor is in good mechan- ical condition. On the other hand, short trips and frequent starting and stopping cause carbon to form rapidly. \ 7JHEN your motor is idling, it is likely that carbon is being depos- ited in the cylinders, especially if you have the bad habit of choking the motor almost until it smokes in order to cause it to idle slowly. Another bad habit is is | ‘racing’? the motor by suddenly opening the throttle while it is idling. This is a certair way of filling your combustion chambers with carbon, for when you open the throttle suddenly, you introduce a charge of gasoline too great to be con- sumed, and the residue always will be carbon. If your motor misses, the cause often will be found in carbon-fouled spark plugs. This condition should be remedied at once, for every time a cylinder misses it becomes filled with gasoline and oil, and, when it does fire at last, this accu- mulation will turn rapidly to carbon. Clean spark plugs with the spark gaps properly adjusted are necessary to the proper operation of your car. Many per- sons make the mistake of assuming that a wide spark gap results in a better spark. This is not so. The spark gap should be between .02 and .025 of an inch, and if you expect your motor to run evenly, every spark plug should have exactly the same adjustment. The best way to assure this is by means of a gage that you can buy for a few cents. N | ANY drivers make the mistake of ad- 4 justing the spark gaps to the width of a‘‘thin dime.”’ A new dime is .05 of an inch thick, and one on which the figures are barely visible is .04 inch. Either of these measurements is too wide. If you haven’t a gage, you can come closer to the proper spark-gap adjustment by using a postal ecard. A postal card is almost exactly .01 inch thick. Two of them are .02 inch thick, exactly the correct width of a spark gap. If you will exercise a little care about these things, I can promise you that your carbon troubles soon will be over. You’ll have a car that will cost you less money in gas, will be more satisfactory to drive, and will take you past other cars on the hills. Ne month—How to detect and trace your automobile troubles from warning noises given by your car.

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How to Build a Super- Heterodyne Set (Continued from page 68) Next, start a wire at terminal F of transformer 59, connect it with terminal F of transformer 58, bend it toward the panel, until it reaches a point about three- quarters of an inch from condenser 43, then bend it toward the right and bend again at a point directly in front of the C terminal of potentiometer 42. Terminate the wire at the C terminal of potentio- meter 42, soldering the end to the terminal. The A terminal of condenser 43, the A terminal of condenser 49, and the in- side end, J, of coil 52 all are connected with the wire just mentioned by short pieces of wire. The F terminal of transformer 60 is connected with the positive A-battery lead that connects terminal 41 terminal 48. Terminal P of socket 57 is connected with terminal 46. HE internal wiring is completed by joining, in the order named, the B terminals of transformers 58, 59, and 60 and terminal 63. All that remains is to solder leads to terminals 53 and 63 for connection with the B batteries. The lengths, of course, will depend on the distance from the set to the batteries. If you have wired units numbers 1 and 3 in accordance with the instructions given in last month’s issue, and have not changed the wiring so as to enable you to use units 1 and 3 together as a simple honeycomb coil receiver, you are ready to connect the three units together and enjoy the programs that the super- heterodyne will get for you. If you changed the wiring, change it back to its original form. You are now units together. One end of the loop aerial, consisting of about 10 turns wound on a two-foot frame, is connected with post 1, and the other end with post 2 of unit 1. The negative A-battery lead is con- nected with terminal 3, and the positive A-battery lead with terminal 4 of unit 1. Arrange the units as shown in the front view of the completed receiver and make the following connections: Con- nect terminals 21, 22, and 23 of unit 1 with terminals 39, 40, and 41,respectively, of unit 2. Then connect terminals 46, 47, and 48 of unit 2 with terminals 24, 25, and 26, respectively, of unit 3. ready to connect the N a receiver of this type, using so many tubes, the low consumption types of tubes should be used. A B battery of 90 volts usually is sufficient for all purposes. Terminal 9 of unit 1 is connected with the negative terminal of the B battery. Terminal 12 of the same unit is connected with the highest B-battery voltage. Terminal 53 of unit 2 is connected with a voltage not higher than 221% volts if a soft tube is used. used, it may be connected with voltages of from 45 to 90 volts. The same con- (Continued on page 158) with | If a hard tube is | POPULAR SCIENCE MONTHLY SUPER COUPLING OR YOUR SUPER Short Wave Coupler (Oscillator Coupler) Gives a uniform output at any frequency from 150 meters to 650 meters. Housed in a bakelite case (exactly like Type R-120) effectively protecting it from injury. Type R-130 Coupler $5.00 10,000 Meter Transformer Filtering) Built to pass an intermediate frequency of 30 kilocycles, together with side-band (26 to 34 kilocycles); other frequencies effec- tively dropped out. Beautiful bakelite housing. Type R-120 Transformer... $6.00 Long-Wave Transformer Broad-Tuned kilo intermediate fre Provides maximum amplification at 30 cycles, as well as at other quencies in standard use, from 15 to 75 kilo cycles (4,000 to 20,000 meters) Type R-110 Transformer $6.00 Audio Frequency Transformers Their uniform reliability and splendid amph fication characteristic are re ognize 1 every where Type R-12, (Ratio 3 to 1) $4.50 Type R-21, (Ratio 5 to |) 1.75 Type R-30, (Push-pull Input) 6.00 Type R-31, (Push-pull Output) 6.00 AN ANNOUNCEMENT BY E. N. RAULAND Asa picture grows to completion under the hand of an artist, so has the world’s favorite audio transformer grown under the development of its engineering staff. Soundly designed Day by day it is brought nearer to perfection; a little refinement of winding here, a little more costly material there—the in perhaps balanced by the adoption of some labor-saving tool, rendered it requires no yearly remodeling | reased cost economical by an enormous output Ina word, the All-American you bought two years ago, unsurpassed a it was at that time, is overshadowed in quality of performance by the All-American of the present day as the strength of a child is exceeded by that of a grown man Continuing, without radical change, the present standard A\i!- American models (Audio, Power, Long-Wave) we shall announce during the months of October and November, achievement in the art of transformer building, surprising in their far-reaching importance even to those long familiar with All-American superiorities. The Radio Key Book is Out—Y ou ée surprise rdered yours, send 10 RAULAND MANUFACTURING CO., 2668 Coyne St., CHICAGO PIONEERS IN THE INDUSTRY AMPLIFYING TRANSFORMERS Largest Selling Transformers in the World

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POPULAR SCIENCE MONTHLY nble of wires, a arrangement of st ? The otherisa neat, well-balanced panel board assembly, Is your radio set a The ‘‘potato patch”’ set is neither at- tractive in appearance nor efficient in operation. It is simply a jumble of wires 1 instruments. ine instruments snoulk xe Mountes F t ts should t ted on t-class panel. Use a good bake- lite panel, preferably Celoron. Arrange r instruments properly on a Celoron pan nd you begin your radio career th one less obstacle to clear rec ption. Celoron is one of the finest insulating t known. It possesses high di € t strength and the abil'ty to resist tmo ric attacks It never chips, « wary or t s. It is practically indestruc- Celoron has been tested and ap- proved by the U.S. Navy and the U.S. CELORON potato patc 999 e Signal Corps. Itisused today by leading manufacturers by thou- sands of radio fans. If you radio and want to build a beautiful cabinet use Vulcawood the new cabinet material If your dealer has not received a supply of Vulcawood, write us. We will send you pamphlet telling you how to build a Vulc: wood cabinet and will give you the address nearest Vulcawood dealer of the Send for FREE booklets We have prepared two interesting booklets **Getting the Right Hook-up with Celoron, and ‘‘Vulcawood—the New Cabinet Material,’ which contain many helpful suggestions for building and operating a radio set. Send for your copies now. They are free. Diamond State Fibre Company Chicago, Ill. Branches in Principal Cities Bridgeport, Pa. Toronto, Canada London, England © BAKELITE RADIO PANELS Protect Your Tools with - NY Om Y lutely fror fl that de olo: or | gum. Makes an excellent ‘d rs autom e anc td other highly fini ed surfaces Buy Nyoil of your dealer or write us. W. F. NYE, New Bedford, Mass. Demonstrate once—results mean sure sale Coast to Coast, lowest prices, attractive four tube instrument $39 50. Big commission to you. Exclusive ter- ritory to proven salesman. Te rritory oing fast, write or wire today. Don’t fail to give name of your county. OZARKA, INC 21 N. Feewen St., CHICAGO, ai. to Build a Super- Heterodyne Set 157) How a (Continued from page ditions apply to terminal 32 of unit 3. Terminal 63 of unit 2 is connected with a voltage of from 45 to 90 volts, while terminal 38 of unit 3 is connected with the highest value voltage of the B battery. Enclosing each unit in a_ separate cabinet the inside walls of which have been covered with tinfoil or other such material used for purposes of shielding will increase the selectivity of the set, but such shielding is not absolutely necessary. Vhile shielding increases the selectivity, it has a tendency to cut down the sensi- tivity and signal strength. The super-heterodyne receiver is fairly simple to operate after a little practice. Once a station is tuned in, the readings of the two dials can be re- corded so that when you desire to listen to that station again, the settings can be adjusted almost instantly. In tuning the set for the first time, begin by setting the tuning condenser 16 at zero, then vary the oscillator con- denser through its range. While doing this, the slider arm of the potentiometer should be set about a quarter of a revolu- tion from the negative terminal A of of the potentiometer. When trying for near-by stations, the or of the tuning condenser 16 can be changed about 10 degrees at a time, and the oscillator condenser may be turned through its entire range as before. For more distant stations a closer adjust- ment is required, and the tuning denser should be turned through degrees or less at a time. When once obtained, the signal can be cleared up and strengthened by adjustments of the two condensers of the Vernier attachments by adjustment of the potentiometer. © not try making any changes in the wiring until after you have tried the set for two or three evenings and have acquired the knack of handling it. If after that time you still experience difficulty due to use of parts of a different type than were used in making this try using different values of capacity in condensers 49 and 50, or disconnect them entirely. Do the same condenser con- five finer by and means any set, with condensers 8, 34, and 43, and with grid leaks 18 and 62 If the set works all right up to the second detector stage but you have trouble when switching to the audio amplifier stages, try the effect of changing your tuning slightly when changing to the amplifier stages. Also try using con- densers of from .00025 to .006 across the primary and secondary windings of the audio transformers, and connecting grid leaks of from 1; to 10 meghoms across the secondary windings of the audio frequency transformers. When properly adjusted and operated, you should have no trouble in pulling in stations 1000 and more miles away on a loudspeaker with a loop aerial. The use of the set with a large outside aerial is not advisable. It can be used, however, with a small indoor aerial by (Continued on page 159) ~—

Page 159

How to Build Heterodyne pba Super- Set (Continued from 1e 158) plugging a honeycomb coil size for the station to mounting 11 of unit 1. Very good results can be obtained also | by using no aerial whatsoever, but con- necting the ground wire with aerial post of unit 1. In that case a honeycomb coil of the proper size should be plugged into coil mounting 11. of the proper received into be In an article next month, Milton B. Sleeper, one of America’s foremost radio engineers, will tell you how to build a short-wave receiving set. Here Are Correct Answers to Questions on Page 78 1. There are about 520 of them that have to do with the moving of the body. 2. It is made up of our sun and the planets that revolve about it. There are eight planets: Mercury, Venus, the Earth, Mars, Jupiter, Saturn, Neptune, and Uranus. 3. They are not only the particles inside of atoms, but the smallest known par- ticles of electricity. An electric current is merely a stream of electrons through a wire. passing 4. So that the bridge shall not be set into vibration by the regular and re- peated tap of the falling feet. Sometimes this makes bridges sway in time with the feet and this may strain their ironwork structure. 5. Yes, exactly; though the ice occupies a little larger volume. 6. Soil is rock that has been broken up and altered chemically by the weather and that contains more or less organic matter left in it by plants that have grown there and died. 7. Because copper carries the stream of electrons with less resistance. A copper wire will carry about six times as much current as an iron wire of the same size. 8. It is a way of expressing how fast energy is being used. One horsepower equals 746 watts of electricity, about 15 times as much current as is burned by an ordinary lamp. 9. In primitive man and lower animals they doubtless served the purpose of keeping insects from crawling into the eye during sleep They still serve to some extent the purpose of keeping things | out of the eyes. | | ; | 10. Because gasoline is more easily | vaporized. The air all around it gets full of gasoline vapor and this makes an ! explosive mixture. Kerosene gives off very little with it. vapor, so this does not happen 11. Aleohol paralyzes the muscles that move the eyeballs, so that the two eyes no longer point in exactly the same direction. This means that the brain gets two sight messages of the same object, one from each eye. | | 12. So far as we know they do not, | though it is possible that the playful | chatter of some of the higher apes | equivalent of our laughter. is an POPULAR SCIENCE MONTHLY Marvelous New w Transformer AGIAN AY \ UN or Our logan *‘The Best Transformer pes mnproved Radio Reception Your Money Back NLESS enthusiastically you can our unconditional money-back guarantee say: «I have never heard aradio Over a year ago our Engineers set out to design give forth such pure, full, rich, 2%¢ develop an Audio Fr y Transformer round. pleasinely natural tones’? wa ‘hat Would raise the quality of radio music and ound, wee ngly natural tones’’ we geehegoae ar e Ith be will promptly return the money you of inte: } Ed + ' ¢ pay us for a pair of KARAS HAR- many thousands of tod But nowt R : MONIK Transformers. new KARAS H ARMOD VIK rer ; . a reality and available for you to u OY That’ ‘ peci ] t 31, fer! ' : ats our special introductory ofrer! Our transi | , ' / ir transformers are being through regular You are both Judge and Jury. jobber and dealer channels t bes ( You will agree that the only criticism of radio ffect comple I mal di If y reception at the present time is that the full a r i our New Kar I k Tr beauty of music is lacking owing to the fa I in K | } or inability of radio sets to reproduce and ty »y I i the rich overtones and ha cs of d } ’ Y>y y t are so necessary to really TRUE 1 l ) now we have been receiving only asi r by ¢ c that y musical tones—that’s why voice and mu ry t and prov VK H struments sound so unnatural in a radio set. The MONIKTransfort W itrisK nef NEW KARAS HARMONIK ‘ Here’s the Offer We Make You have changed all this by reproducing and fully T 1 mail the « we tiling ant amplifyin ig entire tone: he harmo iy + pair 'oti , ton $ equally with fundament il or primary t fr ™ iv t You want the most perfect tone quality a radio of the T: y r set can possibly give you. So does everybody else that new set you are buil You want reception from a P ino to nd like When the Transformers ue % beautiful full toned piano music not like tl p ba ( thin, stringy tones of a heske. The new Karas P Pp Harmonik Transformers will give you such an 4 aise then f p unbelievable volume of delightt ally pure music ¢ 1¢ } that you will be enthusiastically surprised. hs quality You say ‘*Prove this to me and of course I’lluse is vastly improved you are free t your Transformers’’.'To prove itto your entire Iransformers and we w satisfaction is exactly what we propose to do by money im! KARAS ELECTRIC CO., 4040 N. ROCKWELLST. DEPT. 13-67 CHICAGO To Jobbers and Dealers. . . one = * Distribution of Karas Harmonik Trans- = Karas Electric Co., Dept. 13-67 mers throug ecular iobbe e * > rina 7 : b ages a mee =~ * 4040 N. Rockwell Street, Chicago, LIL ealer channels is Delng ca led out as — rapidly as the output of our factory per- = Plea e send me pair of Karas Har mits, In the meantime mail applica- mw Frequency Transformers. I pay the tions will be taken care of in the order ie n delivery, It rstood that I they are received, on an allotment basis, g ‘transformers J ‘ Write us for test records, discounts, etc. ~ 4 is To Set Manufacturers. - We positively prove that Karas Har- . as monik Transformers will vastly improve - the musical quality of your set by any © form of test you wish to impose, When - AD occ og scene vane once lcs you are convinced of this you will nat- a urally want to use them. Write or - wire us and arrangements for tests will RS Ae aE Re be made promptly. — If you send cash with order we'll send transformers " postage prepaid

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Complete Parts for Two-Stage Amplifier May Be Used in Connection With Any Recel ving Set 1 7x9 or any indard Bake- 1 Thor or Columbia High-rat I former. 1 Th rsol ‘ imbia I y + Ir , - ry er. 2 Bake ] S 2B oS $4.q90 lice Tae COMPLETE PARTS FOr 3-TUBE 1 ¢ H ( ( R 6 ( r All All 1-Tube Set ereccecccoscoceooessecs ° 7 Complete Parts for > bd 4-TUBE ~ ACM = REFLEX $ e ; A-2 1 rs @ e 7 ° > co e re e re e e © I) | ’ 6 7 ( - 2 * f . 7 e 2 = e e I ~ + rt ad oe ( r®@ o i e ¢ - ~ 25 ( @ 2 2} ‘ > ® |} | ( 4 ‘ Ww ) = > e - © I . ~ | Dial © s | ad e - neth S ° 'N 14H Wire. @ . + Ont m ¢ i Leak. @ > CRB : ° > 7x21 Pak Panel @ ° 2 - Peas : e oe ( t _fet blueprints $ - ] for wirl % . 4-Tube Set 4 . s . 4 $3985 : a * r . s * 2 1 2 doz. Switch Points ar oft stops 7 Mining Pot Strip, 2 resented. ain article is @ 3 Lf wg pot a 8] Fon . ° tested before shipping. Com- © 1. aE oe argh: AY ire. , Binding sie eet reshman Grid Leak a a: ye A seT ° plete satisfaction guaranteed ° To loss Cone ndenser. 1-TUBE SET 3 Rez .§ 4 or money will be cheerfully Ss fp Py nt ale ; —* 45 y diact 1995 e refunded. e Blue-print —_ Complete emree tions. osm sia ‘45 Secoccceccecoceoscoesoecesooes = 3-Tu > tee ongtiparey aguatiapaprpyties

COMPLETE PARTS SUPER-HETERODYNE a wee 1 23-plate sy s Vernier Bremer Tully or Duplex Condenser. 1 8x36x#:" Dr’ld. Bak. Pan. 1 23 eL s Ve ernier Bremer-Tully or Duple x Condenser. 8 Bakelite Socket 1 4¢ m | P tiometer. 1 1-Meg. Leak 7 Binding Posts $ 75 2 ¢ m Rheostat 2 4” Bakelite Dials 1 Filter Transformer 2 30 m Bakelite Rheostats, 1 Single Circuit Jack. 1 Oscillator Coupler. _ 1.60025 Fixed Condenser. 2 2-Circuit Jac ks. 1 “‘C”’ Battery. 4 .002 Condenser 8 x 35 Baseboard. 1 Battery Switch. 1.006 Conder 35 * Busbar Wire. 1 Bakelite Termi ing al 1 Strip for Bindis ing Posts 3 All-American or Columbia Long-wave Transformers. 1 Mu uce CG ¢ r connecti +* atteries 2 All-American or Columbia Audio Transformers. In price Ane blue-prints and complete layout. RANDOLPH RADIO CORPORATION 159 N. Union Ave. Dept. 25 Chicago, Illinois

ART COLOR PRINTING NEW YORK

——parts u +s, complete parts for complete sets, etc ) a mine of very latest informati oe on all different circuits, com plete list o broadcasting stations, and other valu able, up-to-the-minute radio data. Send your name and address on a card or letter. We will send cata- log free. Free Service Department Our radio engineers will help you solve all your radio problems, and fur nish up-to-date informa tion on set construction ope ration and improve- ment. This service is free to our customers. SOOSHSHHSSOSSESSEC TES

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ROUND the world for rich and poor alike Ingersoll Watches keep vood time and good faith. Ingersolls are doing service as work watches for millions; and as all-around watches 1 millions more. r eee The NEw INGERSOLL Improved YANKEE ‘1-75 The New Improv Waterbury — 4 jewels; stylish 12- Waterbury Radiolite—Lumin- Reliance I size. ** The best watch $5 will $=.00 < ha i f r I t - $6.00 at Low Prices © 7 Reliable Watches buy,” —,

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onsider these Victrola features What records will you use? The Victor catalogs list the great numbers from the musical repertoire of the world. What assurance have you of lasting satisfaction? The assurance that only the highest quality could have established the Victrola as the standard by which all talking-machines are judged. What about cost? The unequalled Victor plant—the largest and most modern in the music industry—is devoted entirely to Victor products, assuring you the utmost value for the price of any Victrola style. “My Victor Records shall be my bi- ography,” said Caruso in an interview published some time before his death. The statement was made during the close association with the Victor Company, which existed throughout the great tenor’s artistic life. The Victor Records by Caruso constitute a library of living music with- out parallel in the history of the art. Hear these and you will want to hear all: Double-faced

ucchella CARUSO Victor Artist I id—O souverain, © juge ,opere! | \ Rachel! quand du Seigneur ae ms of Long Ago 6015 2.00 Love Me or Not Before Galli-Curci had sung a note to any American audience the Victor labo- ratories in Camden had caught imperish- able records of the voice with which she was so soon to conquer another conti- nent. How well our faith in her was justified, how well the public’s judgment was founded—these things are attested again by such records as these: Double-faced

Dinorah—Ombra leggiera GALLI-CURCI Lucia—Mad Scene ee wee am : Lakme < Dov’e l’Indiana bruna 6132 00 \ ictor Artist “pate oles 629 0 Caro mio ben Possession of any Victor Record by Kreisler is possession of a masterpiece. There is little in violin music that he has not explored, humanized, enriched with his own knowledge, and recorded for the Victor Company. On many of his Victor Records, he plays his own compositions. Choose for yourself, but in your choosing be sure you hear these: Double-faced

Liebesfreud 6182 $2.00 Liebesleid Gey eee ; ee am of Youth ( 70 1.50 KREISLER “ebm ofit Victrola No. 400 ye ° The a n ¢ 9790 1.50 vi Victor Artist The Re ; $2503 « There is but one Victrola and that is made by the Victor Company—look for these Victor trade marks i as 7ic tro 1 a ) 7 ‘Victor Talking Machine Company, Camden.N. J. Victor Talking Machine Co. of Canada, Ltd., Montreal

“HIS aaetiatasitn VOICE™