Modern Mechanix, February 1938

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CLOTH FROM MOLTEN GLASS—NEW MARVEL OF SCIENCE MODERN .. A FAWCETT PUBLICATION ay 38t61 ‘aad I i SNULLNSANI GNW 53iaHUH XINVHJSJKA NHUJUUN v. ^ "SEE PAGE 53 B 3 SPECIAL PHOTOGRAPHY SECTION

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Costly Work Formerly “Sent Out” by Business Men Now Done by Themselves at a Fraction of the Expense This is a call for men everywhere to handle exclusive agency for one of the most unique business inventions of the day. Forty years ago the horse and buggy business was supreme—today almost extinct. Twenty years ago the phonograph industry ran into many millions—today practically a relic. Only a comparatively few foresighted men saw the fortunes ahead in the automobile and the radio. Yet irresistible waves of p buying swept these men to fortune, and sent the buggy and the phonograph into the discard. So are great successes made by men able to detect the shift 1n public favor from one industry to another. Now another change is taking place, An old established industry—an integral and important part of the nation's structure—in which millions of dollars change hands every ycar—is in thousands of cases being replaced by a truly astonishing, simple inven- tion which does the work better—more reliably —AND AT A COST OFTEN AS LOW AS 2% OF WHAT IS ORDINARILY PAID! It has not required very long for men who have taken over the rights to this valuable invention to do a remarkable business, A Money-Making Opportuni for Men of Character EXCLUSIVE FRANCHISE FOR AN INVENTION EXPECTED TO REPLACE A MULTI-MILLION-DOLLAR INDUSTRY EARNINGS One man in California earned over $1,600 per month for three months—close to $5,000 in 90 days’ time. Another writes from Delaware—''Since I have been operating (just a little less than a month of actual selling) and not the full day at that, because I have been getting organized and had to spend at least half the day in the office; counting what I have sold outright and on trial, I have made just a little in excess of one thousand dollars profit for one month.” A man working small city in N. Y. State made $10,805 in 9 months. Texas man nets over $300 in less than a week's time. Space does not per- mit mentioning here more than these few random cases. How- ever, they are sufficient to indicate that the worthwhile future in this business is coupled with immediate carnings for the right kind of man. One man with us has already made over a thousand sales on which his earnings ran from $5 to $60 E sale and more. A great deal of this business was repeat usiness. Yet he had never done anything like this before coming with us. That is the kind of opportunity this business offers. The fact that this business has attracted to it such business men as former bankers, executives of businesses— men who demand only the highest type of opportunity and income—gives a fairly good picture of the kind of business this is. Our door is open, however, to the young man looking for the right field inwhichto make his start and develophis future. and show carnings which in these times are almost unheard of for the average man. Not a “‘Gadget’’— Not a ''Knick-Knack"— but a valuable, proved device which has been sold successfully by busi- ness novices as well as seasoned veterans. Make no mistake—this is no novelty—no flimsy creation which the inventor hopes to put on the market. You robably have seen nothing like it yet—perhaps never reamed of the existence of such a device—yct it has already been used by corporations of outstanding prominencc—by dealers of great corporations—by their branches—by doc- tors, newspapers, publishers—schools—hospitals, etc., etc., and by thousands of small business men, You don't have to convince a man that he should use an electric bulb to light his office instead of a gas lamp. Nor do you have to sell the same business man the idea that some day he may need something like this invention, The need is already there— the moncy is usually being spent right at that very moment —and thc desirability of saving the greatest part. of. this- expense is obvious immediately. Some of the Savings You Can Show You walk into an office and put down before your prospect a letter from a sales organization showing that they did work in their own office for $11 which formerly could have cost them over $200. A building supply corporation pays our man $70, whereas the bill could have been for $1,600! An automobile dealer pays our representative $15, whereas the expense could have been over $1,000. A department store has expense of $88.60, possible cost if done outside the business being well over $2,000. And so on. We could not possibly list all cases here. These are just a few of the many actual cascs which we place in your hands to work with. Practically every line of business and every section of the country is represented by these ficld reports which hammer across dazzling, convincing money-saving opportunities which hardly any business maa can fail to lerstand, Profits Typical of the Young, Growing Industry Going into this business is not like selling something offered in every grocery, drug or department store. For instance, when you take a $7.50 order, $5.83 can be your share. On $1,500 worth of business, your share can be $1,167.00. The very least you get as your part of every dollar’s worth of business you do is 67 cents—on ten dollars’ worth $6.70, on a hundred dollars’ worth $67.00, —in other words two thirds of every order you get is yours. Not only on the first order—but on repeat orders —and you have the opportunity of earning an even larger percentage. This Business Has Nothing to Do With House to House Canvassing Nor do you have to know anything about high-pressure selling, ''Selling'* is unnecessary in the ordinary sense of the word. Instead of hammering away at the customer and trying to "forcc'" a sale, you make a dignified, business-like call, leave the installation—whatever size the ‘customer says he will accept—at our risk, let the customer sell himself after the device is in and working. This does away with the need for pressure on the cus- tomer—it climinates the handicap of trying to get the money before the customer has really convinced himself 100%. You simply tell what you offer, showing proof of success in that customer's particular line of business. Then leave the invention without a dollar down. It starts working at once. In a few short days, the installa- tion should actually produce enough cash money to pay for the deal, with profits above the investment coming in at the same time. You then call back, collect your money. Nothing is so convincing as our offer to let results speak for themselves without risk to the customer! While others fail to get even a hearing, our men are making sales running into the hundreds. They have received the atten- tion of the largest firms in the country, and sold to the smallest businesses by the thousands. No Money Need Be Risked in trying this business out. You can measure the possi- bilities and not be out a dollar. If you are looking for a business that is not overcrowded—a business that is just coming into its own—on the upgrade, instead of the downgrade—a business that offers the buyer relief from 2 burdensome, but unavoidable expense—a business that has a prospect practically in every office, store, or factory into which you can set foot—regardless of size—that is a necessity but does not have any price cutting to contend with as other necessities do—that because you control the sales in exclusive territory is your own business— that pays more on some individual sales than many men make in a week.and sometimes in a month's time—if such a business looks as if it is worth investigating, get in touch with us «t once for the rights in your territory—don't delay— because the chances are that if you do wait, someone else will have written to us in the meantime—and if it turms out that you were the better man—we'd both be sorry. So for convenience, use the coupon below—but send it right away—or wire if you wish. But do it now. Address IF. E. ARMSTRONG, President Dept. -:^-B, Mob Ala. — om =m ee e ee — RU $ FOR EXCLUSIVE i l TERRITORY PROPOSITION l F. E. ARMSTRONG, Pres., Dept. 4ui9-b. Mobile, Ala, L} Without obligation to me, send me full infor- mation on your proposition, 1 Name. Street or. Route. I l V Box No... l City.. State : l wt lo see maim ue. NS |

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*...and I had no money”? “A MAN can knock along on what he's making until something happens! Then when the emer- gency comes and the money he hasn’t got could do so much, the cold realities of life haunt him. “T know what I am talking about! forget the time when my chi Not an extra dollar ta my tame. for friend:.... “But now I am able to meet the emer life without depending on my friends. Ta st atiis an International Correspondence Schools Course and got the training I needed to earn more money. TIl never at stake. t been z life was Tr. Rod iz it Dan It was the wisest thing I ever did. I realize it every time I get another promotion!” * * 1 Is money one of your problems? Does every un- usual situation in your family life frighten you because of the lack of it? Remember this: It’s the trained man today who makes money and : And thousands of men have acquired this training by spare-time study of I. C. S. Courses. So can you! Don't delay —tomorrow never comes! Mark and mail the coupon—today! BOX 2316-P, SCRANTON, PENNA. Without cost or obligation, please send me a copy of your booklet, “Who Wins and and full particulars about the subject before which I have marked X: Wh TECHNICAL AND INDUSTRIAL COURSES O Sheet Metal Worker C Boilermaker Z Telegraph Engineer Telephone-Work D Radio Mechanical Engincering Mechanical Draftaman Machinist D Toolmaker teramaker Engines a Engines 5b Mechanic O Heat Treatment of Metais BUSINESS TR D) Business Management Q Industrial Management O Traffic Management Q Accountency = O Cost Accountant = D C. P. Accountant [e DOMESTIC O Home Dressmaking D Advance: D Professional Dressmaking and Designing rem! Age 5E International Correspondence Schools Canadian, When Answering Adi O Plumbing O Heating O Air Conditioning D Steam Engineer O Steam Electric Engineer O Marine Engineer O R. R. Locomotivea O R. R. Section Foreman O Air Brakea [] R. R. Signalmen O Highway Engineering D] Civil Engineering O Surveying and Mapping AINING COURSES vice Station Salesmnanehip First Year College Subjecta Business Correspondence = Stenography and Typing Z Civil Service O Mail Carrier C Railway Mail Clerk Bi Stream Fitting 0 Ventilation SCIENCE COURSES Z Millinery * D Bridge Enginoer Lj Bridge and Building Foreman D Chemistry Li Pharmacy E] Coal Mining O Mine Foreman T] Navigation D Cotton Manufacturing O Woolen Manufacturing O Agriculture O Fruit Growing O Poultry Farming O Fire Bosses O Grade School Subjects L1 High School Subjects E College Preparatory O illustrating LJ Cartooning OU Lettering Show Cards [O Signe O Foods and Cookery 5 Tea Room and Cafeteria Mansgement, Catering „Address. Limited, Montreal, Canada nents Please Mention February Modera Mechanix

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PRICE February 15 CENTS 1938 SAME PRICE Volume XIX IN CANADA Number 4 Circulation over 250,000 Copyright 1938 by Fawcett Publications, Inc. j A L G t In This Issue Modern Photography Section SPECIAL FEATURES Glass Cloth—New Marvel Oi Science 35 Winners Of Photo Awards ...... 103 Flying The Subway Express 38 By Donald G. Cooley Modern Photo Spotlight .......... 104 Darkroom Lamp Tilts To Àny ABgle- patinais LOT Science Battles Fog Menace - - - - - 42 Tricks Of The Composite By Bob Gordon l Photograph ssssssisssssrrsersrres 108 Camera And Darkroom Kinks 110 Man Makes His Own Rubber - - - =- = 50 How Camera Shutters Work.. 112 Copying Device ......... ato. TIA Uncle Sam—Model Maker- - - > - «+ 58 opying Device By Walter E. Burton Photo Puzzlers esee 116 Color Films—A "Hobby" Invention - + >- 66 Each month MM offers cash awards for the best pictures sent in by amateur photo fans. By Montgomery Mulford For full details see page 103. Stamps And Railroad Anniversaries - - =- 70 Landing Your Fish Throughice- - - - - 88 By Dad. Williams NEXT MONTH In addition to many interesting and novel workshop projects that will provide ample outlet for your skill with tools, readers will find (Continued on page 10) many general features of an in- teresting and informative nature. Published monthly by Fawcett Publications, Ine., 11th St, & Broadway, Louisville, Ky.. U. S. A. Business office, 22 West Putnam Are., Greenwich, Conn. Entered as second-class matter under the Act of March 3, 1879, at the post office in Louisville, Ky., with additional entry at Greenwich, Conn, Editorial offices: 1501 Broadway, New York, N. Y. Not responsible for unsolicited manuscripts, In U, 8. and Possessions and in Canada, 15c a copy; $1.50 a year, Send subscriptions to Greenwich, Comm., address, Other Postal Unions, $2.00 a year. East Indian Agent, P. C. Eranee Sons, Bombay, India, Printed in U. S. A. Advertising farms close the first of second month. preceding date of issue. Advertising offices: New York, 1501 Broadway; Chicago, 360 N. Michigan Ave.; San Francisco, Simpson-Reilly, 1014 Russ Bldg.; Los Angeles, Simpson-Reilly, Garfield Bldg. Member Audit Bureau of Circulation, : . W. H. FAWCETT, Publisher RALPH DAIGH, Managing Editor ROBERT HERTZBERG. Editor AL ALLARD, Art Director THOMAS A. BLANCHARD, JOHN L. SCHERER, CLIFFORD PETERS, Associate Editors S. S. RABL, Naval Consultant

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Be Somebody- ND there is something. Here it is: Become an „À Accountant; train at home in your spare time— with LaSalle! Fit yourself to get bigger pay in a modern respected profession. Prepare yourself to get what you want from life—a home, money for education, a car, luxury for your family—everything you've hoped for! Accountancy through home study opens two fields for you. First, it can put you in line for higher bracket jobs in your present company. It can give you the drop on untrained men—can lift you out of their class. Your increased value will quickly be apparent in your work and noticed by your superiors. Accountancy training can give you ability and experience for which business is looking—for which it is glad to pay. The second opportunity LaSalle Home Study Ac- countancy offers is a profitable profession of your own! Right now the professional accountant faces a greater demand than ever before. It is’not uncommon for trained accountants to earn $3,000, $5,000 and more. Three Men Who Proved It Can Be Done Read the actual experience of three men who started accountancy training with us in 1936: After a short period of intensive study, the first man started bookkeeping jobs on the side. Soon he got » Get more money; prestige; a betfer career You can do it. Read this € “YOU KNOW, MARY, 1 DREAMED OF BETTER THINGS FOR Us— BUT SOMEHOW PVE FAILED TO : GET WHAT WE HOPED FOR—" € “1 KNOW, JIM — WE'VE WORKED HARD, TOO. BUT YOU DO WORK ANYONE COULD DO. THERE MUST BE SOMETHING—” enough of them so he opened kis own business. Today he is his own boss, a successful business man with a splendid income. All in one year! . Another member—five months after starting his study— was called into the office and given a more responsible position paying $40 a month more. His employer told him anyone studying a LaSalle home- study course was obviously more alert than most men and therefore capable of a bigger job. To the employer of the third member we sent infor- mation about the member's study. The letter resulted in his being chosen—above five other candidates—for a better position with shorter hours and more pay. Just three of thousands who tell us that LaSalle home study was the turning point in their lives. Their cases, which may seem extraordinary to you, are not uncommon to us. Many others have done as well. Perhaps you can, too. Át least, it's worth investigating. Send for This Free Book The facts about LaSalle training in Accountancy and the opportunities in this growing field are clearly out- lined in a 64-page book which LaSalle will send you free. If you have the urge and the will to increase your income, clip and mail the coupon for it—NOW. LASALLE EXTENSION, Adult Business Training, Dept. 2493-HR, Chicago, lll. T'd like to see whether I should take up Accountancy. Send me—without obligation or cost to me—your booklet Accountancy, the Profession That Pays, and full information about your Accountancy training program. O Higher Accountancy i Other LaSalle Opportunities: Jf more interested in one of the fields indicated below, check and mail now. (Business Management LiModern Salesmanship LjLaw—Degree of LL.B. LiCommercial Law DjRailway Accounting DJExzpert Bookkeeping L)Practica] Accounting and Office Management Oc. P. A. Coaching Business Correspondence Business Englis LiStenotypy When Answering Advertisements Please Mention February Modern Mechanix 5

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ANY MAKE 50575 A WEEK pisen] | | Will Train You at Home— mail coupon for FREE Book has directed th Do you want to make more money? Radio offers you many opportunities for well-paying spare time and full time jobs. You don’t have to give up your present job, leave home or spend —Ó a lot of money to become a Radio Expert. ator Broadea cet OP Eon s Dom Many Radio Experts Make «when I completed | j»deast, | x a $30, $50, $75 a Week tained mind E diately now C iet Radio broadcasting stations employ engineers, operators, sta» fieense PC, ua p. HATES, tion managers and pay up to $5,000 a year. Spare time Radio perator.” — } > Mich. set servicing pays as much as $200 to $500 a ycar—full time Madison Ste ^77 jobs with Radio jobbers, manufacturers and dealers as much A ii as $30, $50, $75 a week. Many Radio Experts operate their ovn full time or part time Radio sales and service businesses. Raie manufacturers aud jobbers employ testers, inspectors, , oremen, engineers, servicemen, paying up to $6,000 a year. "My pl jn Spare Time 2 Radio operators on ships get good pay, see the world besides. servicing, with "Bane. pina Radio set Automobile, police, aviation, commercial Radio, and loud tems "work—all in me nara T speaker systems are newer fields offering good opportunities earnings in Radio amount to SP 1 ; now and for the future. Television promises to open many $10 a week." —WILLIAM MEYER - : good jobs soon. Men I trained have good jobs in these MS Ridge Road, Hobart, Ind, F branches of Radio. Read their letters in my 64-page book. Mail the coupon. There's a Real Future in Radio vo man with Store for Well-Trained Men Head Regio. man of the Steren Radio already gives good jobs to more than 300,000 people. «qam head Bad anta, Ga., making And in 1936, Radio enjoyed one of its most prosperous Siores, ne eomm ons. I years. More than $500,000,000 worth of sets, tubes and aalay, Pianta’ pest t É parts were sold—an increase of more than 60% over 1935. p my succe: enm wat Over a million Auto Radios were sold, a big increase over Q, CARA Eco 1933. 24,000,000 homes now have one or more Radio sets, and more than 4,000,000 autos are Radio equipped. Every year millions of these sets go out of date and are replaced with newer models. More millions need servicing, new tubes, repairs, etc. A few res $30, $50, $75 a week » A ae jobs have grown to thousands in 20 years, And Radio is $200 to $300 a Month in Own Business E still a new industry—growing fast! “For the last 18 months I have b in business for myself, making bet Many Make $5, $10, $15 a Week Extra in Spare Time While Learning $200 and $300 a m N. R. I. to thank for my siet Im i feld.” ARLIE J. FROEHNER å A 3 W. Texas Ave., Goose Creek, Texas, Almost every neighborhood needs a good spare time service- man. The day you enroll I start sending you Extra Money Job Sheets. They show you how to do Radio repair jobs, how to cash in quickly. Throughout your training I send you plans and ideas that have made good spare time money— 1 n for TWO Stores from $200 to $500 a year—for hundreds of fellows. I send rvicema" own Work, E you special Radio equipment and show you how to conduct ‘ oF ouk for two experiments and build circuits which illustrate important g serve a salary a oto B Radio principles. My training gives you PRACTICAL i am paid On NA ER E EXPERIENCE while learning. f WEEE A iamsport, i Accept No Substitutes! Always Insist on the Advertised Brand!

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SET SERVICING. Spare time set servicing paye many $5, $10, $15 a week extra while learning, Full time servicing pays as much as $30, $50, $75 a week. BROADCAST. ING STATIONS. Employ munagers, engineers, oper- ators, installation and maintenance men for fascinating jobs and pay up to $5,000 a year. I Give You a Professional Servicing Instrument Here is the instrument every Radio expert needs and wants—an All-Wave, ^ All-Purpose, Set Servicing Instrument, © It contains everything necessary to measure A, C. and D. C. voltages and current; lest tubes, resistance; adjust and align any set, old or new. Tt satisfies your needs for professional servicing after you gradu- ate—can help you make extra money servicing sets while training. LOUD SPEAKER SYSTEMS. Duilling, installing, servicing and operating publice ad- dress systems is another growing field for men well trained in Radio, You Get a Money-Back Agreement I am sure I can traln you successfully. I agree in writing to refund every peuny you pay if you are not satisfied with my Lessons and Instruction vice when you finish, I'll send you a copy of this agreement with my Free Book, AUTOMOBILE RADIO. Another new Radio field—sclling, iu- stalling, servicing, One milllon ov more auto owners will install radio sets within the next sear, Find Out What Radio Offers You Act Today, Mall the coupon y for “Lich Re sin R free to any felluw over 15 soli I Ru thue and full time opportuni ec Television; tells alout my training in Radio you letters from meu I trained, telling w d earning. Find out what Radio offers YOU! [AIL THE COUPON in an envelope, or paste on a postcard —NOW ! J. E. SMITH. Pres., National Radio Institute Dent, 88H Washington, D. Q J. E. SMITH, President, Dept. 8BH National Radio Institute, Washington, D. C. Dear Mr. Smith: Without obligating me, send "Rich Rewards in Radio," which points out the spare time and full time opportunities in Radio and explains your 50-50 method of training men at home in spare time to become Radio Experts. (Please Write Plainly.) NAMH m ———ÁÁ— P ÓD AO spirer When Auswering Advertisements Please Mention February Modern Mechanix 7

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How To Determine The Patentability Of Your Invention Before you spend money in making a model, or spend weeks in its design, we advise you first to have a preliminary search made through U. S. Patents in the U. S. Patent Office to see if there are inventions like yours already on record; and, if sc, let us give vou our opinion as to the patent- ability of what vou have. We employ experienced searchers to perform ihis service for you. From the reports of our searchers we can quickly form our opinion as to whether your invention is conironted with ob- stacles in the form of already granted patents. First get our FREE BOOK and read the chapter on "How Can I Know Whether My Idea Is Patentable ?” How We Serve The Inventor 7; LIESS every state in the Union. Our organization is a large and efficient one. Our practice is con- fined entirely to Patents, Trade-Marks, and Copyrights. We have had vears of experience in Patent Matters. When you place your in- vention in our hands, we are in position to proceed at once to secure protection for you. Our fees are reasonable, and, if you desire, we can arrange convenient terms of payment, 8 Accept No Substitutes! CLARENCE A.OBRIEN & HYMAN Help is the Patent Attorney? Your invention may provide your life's greate est opportunity. If it is to bring income to you it should be legally yours. Upon your patent attor- ney’s skill rests how completely your patent covers all the protectable points in your invention. The inventor may actually lose money on his invention by overlooking a single claimable point that a skilled patent attorney would not miss. What The Inventor Must Know »; gie the inventor must follow certain definite steps that precedent has established as the quickest way to reach his goal. Our FREE BOOK, "Patent Guide for the Inventor," gives a concrete logical, and thorough resume for the inventor to follow. It takes him, through 48 pages, from the crude first model to the finished commercial product. It shows the inventor how to avoid mistakes, how to shorten the road in getting his invention ready for market; it also points out how to save money and avoid the errors of inexperience in applying for patent. Getting our FREE BOOK should be the first step in definitely declaring yourself an inventor. , After you get this illustrated, clearly worded guide of care- fully compiled patent knowledge you will know how to proe ceed without expensive mistakes and discouraging setbacks from “wrong-track” methods, Always Insist on the Advertised Brand!

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Keen competition in every form of in- dustry has put manufacturers feverishly at work trying to speed up output, reduce overhead, save on materials, outsell trade opponents. The inventor is the key-man in making advancement possible to any business, Upon the inventor rests the success of many enterprises. This does not mean that you must have something gigantic to win commercial success. Anew way to open a door or button up a shirt may be the looking for. The Importance Of immediate Action In making application for pat- ent it is important to be first. Even if your application is de- layed by a few days you may be placed at a disadvantage. The short time that elapsed be- tween Elisha Gray's application for his telephone patent and the application of Alexander Graham Bell probably cost Gray the rights to the tele- phone. very thing hundreds of manufacturers are If you have something novel —if it is practical to manufacture— no matter whether it be an improved rattle for a child or a whistle for a mechanical automobile, there is likely a wait- ing market, FREE RECORD OF INVENTION This FREE FORM Record of In- vention Form enables you to make 1n con- venlent form a sketch of your invention and have it wit- nessed in a manner of value to you should the occasion for evidence arise, THE COUPON and oblain our FREE BOOK and Record of Invention Form, CLARENCE A. O'BRIEN i & HYMAN BERMAN Le 3179 Adams Building Washington, D. C. Registered Patent Attorneys Before U. S. Patent Office Please send me at once your Big Free 48-Page Book, “Patent Guide for the Inventor" and your ‘pecially Prepared ‘Record of Invention" form. ‘his request does not obligate me. NAME When Answering Advertisements Please Mention February Modern Mechanix 9

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Betis, ee ee PS E. [-——3 BEE EE F E A eget are ae — ot — a] [—5—1 lh Da ee ae oa os L— a a et " [9 —1 emn am pn — — 17] ea or we po eee oe ay ee muma os ons [—E—| = o oan on oe wa I oa we we Las BOOKS SENT FREE! a ON APPROVAL 5 VOLUMES BRAND NEW EDITION Only 15 minutes a day with these WON- DER BOOKS can prepare you for a good drafting job in less than a year, Mechani- cal and architectural drafting from simple straight lines to important complex plans. A step at atime! Built especially for be- ginners, for men with only grammar school- Drafting room practice, PLUS EN- For Beginners Written, so you can understand every wore, by 22 well known engi- ing. neers and architects. GINEERING, made easy and clear. fn- DeLuxe flexible binding, eludes complete course in — blue-print nearly — 2,000 pages, reading, : i 1546 blueprints, charts Big Fjeld Big Demand Big Pay and diagrams; prepares n Competent draftsmen ar 11 you for a good drafting p nen are urgently needed right now in all building and manufacturing jab in mechanical or lines at 530.00 to $73.00 a week. That’s architectural lines. Sent Just the beginning—FOR DRAFTSMEN HAVE for 10 d ^n : aml- THE BEST CHANCES FOR ADVANCEMENT. or. ays Irce exami- pleasant, fascinating work, easy to learn and nation if you mail cou- «do. Learn quickly with these books—send pon immediately, coupon for a set and see for yourself. Th I trume t Pi year's egnsulting Ecnberoniy in the merican ecimicai joctety Row cem í dud "d Tumenis io all readers of this famous cycloped ia z] rafting. Many soy that it is worth more neiude than the cost of tha books. Complete set of drawing instruments if you send for these drafting books NOW, These instruments are made of the finest of German silver, are absolutely accurate and are packed in velvet lined leatherette pocket case. Real $10 value, but included with these books. AMERICAN TECHNICAL SOCIETY ain Dept. D-2320, Drexel at 58th St.. Chicago, lil, — — — MÀ — À e i m$ am Miam ium mu em wm emm m Lp sw reram — American Technical Society, Dept. D2329, Drexel at S8th St., Chicago, IIl. Send for 10 days' al New 5 volume set of drafting. I will pay the few cents delivery charges. If I wish, I may return books In 10 days and owe you nothing, but_if I decide to keep them, I will send $2.00 after 10 days, then only 83.00 a month until $24.80, the adver- tising price, is paid. Send latest edition and include drawing instru- ments and Membership Certificate. Name .-.-.22l222.l2o22l--22222ll2222l2lll22gllgcezen2cll.. Address Attach letter stating that of at least one bus ga um m ee mm cn I : Which i of These EA i i Do YOU Want? | No special education or experience usually required. Steady work. Short hours. Vacations. PENSIONS: Age 18 LA 0. Extra Social Sec X ected soon. MEN-WOMEN ook. Tested Method v ü Civil Service Examina START $1.260 to OsSibl pointiment. Liquor-Gauger Arthur R, " Stenoprapher ü ] Meat Inspector Custom House Ofiice Clerk—Typist Accountant 3 File Clerk L Income Tax Auditor Patterson, {Former Govt. Examiner) rincipal, TERSON $ . 432 Mercantile 8 Eier Send FREE Government Ic Icing. Rochester, N. Y. Hew to Secure a Name *Giftmaker Sr." - (Oulsida U, S. A. & C. 0. D. $5.15* A heavy duty, smooth lathe at a S emarkal f long, 7^" high. Turns p diameter by 24". Ful 2-spesd. Weighs 10 Ibs. and short tool rests. OILLESS b ings. Satisfactlon guaranteed or money back. d Free Catalog describing cash prize M contest and illustrating complete pover tool line: Shaper or Circular Saw with oilless bushings, $3 each: Drill Press. $2.50; Jig Saw, $1.50: 912" Lathe, $2; Sander, $1, cte. Order today 'or'send card for catalog. CONTENTS—Continued from page 4 HOW-TO-BUILD FEATURES Novel Cigarette Automat - - - - - - *71 Steps In Making An Inlaid Footstool 72 You Can Learn Glass Blowing - - - - - 476 Build This Sturdy 12-inch Band Saw 81 Home Science Stunts With Soap - - - 86 Hammered Copper Ware For Home Crafts- men - - - - - = - - - = = = 92 Microscope Discloses Real Identity Of Fur Samples - - - - - - - - - - - 96 FOR THE WORKSHOP FAN These Winter Projects Are Easy To Make - 74 Build This Modern Radiator Grille - - 75 Pipe Fittings Make Blow Torch Stove Home Use - - -- = - - - - - 7 Roofing Holds Pipe In Place. I ' t I I -] Ls) Paper Clips Aid Soldering - - - - - - 79 Blade Holder Gives Even Cut - - - - - 79 Practical Home Suggestions - - - - - - 80 A Port-Hole Door Knocker - - - - - = 85 Sander Aids Sticking Door - - - - = = 85 I Li 1 1 [| to pS Hammer Handle Holds Tacks Ball Prevents Hammer Slips - - - - - 95 Electrical Kinks For Snop And Home 98 NEW MECHANICAL INVENTIONS Foot-Powered Vehicle Travels On Water Or Land e =.= = = 6 = & — m8 Wind Charger’s Vanes Fold - - - - - - 37 Device Exposes Drunkards - - - - - - 46 Street Alarm Box Calls Either Police Gr Fire- men - -------- - - = 49 Camera On Police Revolver Snaps Evidence 49 Belt Drive Replaces Wheels On Novel Motor- cyce - - = = - - - - - - = 53 Power-Driven Timber Saw Has Stationary Blade - =- =- =- ------- 58 Foot Pedal Controls Mainsheet Of Ice Yacht 54 Machine Analyzes Coloring - - - - - - 55 Eye Exerciser Apparatus Resembles Circus Wheel - - - - - - - = - - - - 61 "Planeometer" Detects Pavement Deviations 62 Fire Box Traps Pranksters - - - - - - 65 "Legcuff'" Prevents Running - - - - - 65 Machine Air-Conditions Tent - - - - - 68 Machine Cuts And Blows Hay Into Truck Or Barn - =- - - - - - = = = = = 69 [Continued on page 14] Accept No Substitutes! Always Insist on the Advertised Brand!

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UNION Ed ue. BU = TELT oes nuw TOR 0 west! Yauna pear 9 nos ameEr per STABLISHING new mileage records on cars in all sec- tions of the country, the Vacu-matic again scores in a new speed record established by Bob McKenzie transcon- tinental automobile champion. Los Angeles to Chicago — 2,322 miles in 39 hours and 42 minutes— driving 75 and 80 to maintain a speed average of 59.7 miles per hour! Here is speed—a gruelling grind—where quick accelaration, greater top speed — and less stops for gasoline mean those precious moments saved that make new speed records possible ‘The same Vacu-matic that helped Bob McKenzie establish this speed record and gave him such fine gas savings is now available for all car owners. It is positively automatic—simple to install—inexpen- sive—and pays for itself many times over in gas savings. QutsmaLz +» Nothing Like It! Vacu-matic is entirely different! It operates on the super- charge principle by automatically adding a charge of extra oxygen, drawn free from the outer air, into the heart of the gas mixture. It is entirely AUTOMATTIC and allows the motor to “breathe” at the correct time, opening and closing automatically as required, No idl- ing troubles—no carburetor adjust- ments necessary. It is so simple it will amaze you—so practical it will save you many dollars on gas costs. Fits All Cars VACU-MATIC is constructed of six parts, assembled and fused into one unit, correctly adjusted and sealed at the factory. Nothing to regulate, Easily attached in ten minutes. The VACU-MATIC Co. Wauwatosa, Wis. Agents and Salesmen VACU-MATIC offers a splendid opportunity for unusual sales and profits. Valuable terri- tories now being as- signed. Check and mail coupon. Guaranteed Gas Savings VACU-MATIC must prove itself on every car. It is guaranteed to give worthwhile gas savings, quicker pick-up and more power, or it costs you nothing. “On my V-8 Ford it works miracles", says Ralph Fields. James Seeley “On an International Truck on a round trip to Cleve- land, 385 miles, it saved 19 gallons of gas.” A. V. Grove —“On the Buick it showed 5 miles more per gallon.” F, S. Peck—"T average 22 miles per gal. on my Plymouth, an increase of 7 miles, for a saving of $15.00 a month, or $180.00 a year." Wm. Lyons—" Averaged 25 miles on a gal. with a Model A Ford at 40 miles per hour.” Free Details You owe it to yourself to know all about this remarkable discovery, Mail the coupon below. Start saving gas with VACU-MATIC and enjoy a new driving thrill! There’s no obligation—so get the facts now! Write today! -æ c we i» e = = -PREE OFFER COUPON =- = = 4 THE VACU-MATIC COMPANY 7617-357 W. State St, Wauwatosa, Wis. Gentlemen: Please send me full particulars concerning the Vacu-matic and details of your Free Offer. This of course does not obligate me in any way. Name . rested in selling proposi z "-— m m € ue m n "A When Answering Advertisements Please Mention February Modern Mechanix 1i

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Since the ‘‘Horseless Buggy” Days, We Have Helped Inventors pes you have already heard about our firm, because one client tells another—and we have served men 3n every state in the Union, and in nearly every foreign country. We have been working with inventors since 1898. If you have a good inven- tion—or an idea for one—and don't know what Victor J. Evans & Co. can do for you, NOW is the time to find out. How We Can Help You Both the Patent Office and ihe U. S. Supreme Court have made it clear that the inventor needs the assistance of a competent patent lawyer when it comes 1o protecting an invention. It is onc thing to think up a good invention—it is another to get effective patent protection on it. For more than a third of a century —it has been our business to give sound advice and counsel to in- ventors. Our free books (described on the opposite page) tell what steps to take first, how to protect your- self, how the law protects you, what you must do, when to offer your in- vention for sale, how others have succeeded, and much more. You need this information. Simple Inventions May Have Excellent Com- mercial Possibilities FREQUENTLY inventors confuse the size or the complication of a device with the question of commer- cial value and patentability. These two factors, of course, have no re- lation to each other. Most of our present-day complicated machines represent a process of evolution, a series of inventions. On the other hand, every so often some inventor comes along with a very simple “gadget” which possesses the ele- ments of broad utility and is patent- able. Scme of the most profitable in- ventions have been of this latter class. Shown above are a few such examples. Whether a device is simple or complex, if it represents a forward step to save manufacturing costs, to save labor, or to add enjoyment to human life, it may prove patentable and profitable. This subject is more fully discussed in the bceoklet en- titled ‘‘Patent Protection" shown on the opposite page. ee DAYI SARNOFF, once a poor lad and now the famous President of ihe Radio Corporation of America, in an article in Liberty Magazine states: “Civilization means elimination of un- necessary labor. The sewing machine and the vacuum cleaner save millions of women from backbreaking toil. The iractor makes the farmer's life bear- able. The automobile lends wings to us all The airplane is our magic carpet. It would be madness to slow up invention because our trouble is not that mechanical science moves too speedily, but that the governmental and social sciences move too slowly e... In a world reorganized to vibrate within certain wave bands, human intelligence will be able to dis- tribute equitably nature's boun- ties from above and below, and make princes of paupers." What Will Be Next? VER since George Washington signed the first patent, America has led the world in inventions. It may be said that not a year has gone by without some important inventions being patented and commercialized. David Sarnoff, president of the Radio Corporation of America, sees a big future ahead for science and inven- tion. Just as sure as the sunrise, 1938 will see new inventions come out— new wealth made from patents. Your idea may be one of them. You never can tell. For this reason you should send for our books tocay and get the facts about patents and inventions. 12 Accept No Substitutes! Always Insist on the Advertised Brand?

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These FREE books tell you Get the answers to your questions: How can I protect my invention? When can I show my invention ta manufacturers? When can I offer it for sale? How should I go about selling it? Can I get protection with- out a patent? What are my em- ployer's rights? These and other imm- portant questions are fully answered, Learn how our patent laws protect you The U. S. has liberal pate ent laws, an much of our national wealth is based on pate ents. In tact, a Japanese come | mission decide that American progress was mainly due to our patent laws. These laws are made to protect you. Find out about them now. This is for your own good. Mail Coupon Today Delays are dangerous. If you have a good invention you should get protection for it just as soon as possible. Don't turn this page until: you have clipped and mailed this coupon—you will hear from us by returu mail. x NIS E € Y 115 Mechanical Principles WASHINGTÓSS aset BIN JE CHAR a K a jeest Ye B,D aüdnoct a petes egnen ano other Of 1445-9 Yopart 2. bos An n and "V e ranch Shown 1010-B. id Bldg., p Protection.’ SM any of 405-5, G ooks, “rater ipplied 3 s of yol te; Same Request the book "Patent Protection" (sent free send me FREE on DI NE m to inventors). Not only does it tell you what to do How 10 Fred abel 000000 use gan for protection, and how to do it—it also shows you M T c T i s+ 115 different mechanical movements that you may i "——— - a use in developing your own inventions. Inventors MESE alleen State. 3 tell us they have found these useful. sureet and Now T mE Se AN: cus or Tem When Answering Advertisements Please Mention February Modern Mechanix 13

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AIR CONDITIONING ELECTRIC REFRIGERATION RAE Aa cea for ee ao i quirements, we will train you in spare time at home for a Good pay position as an Installation s. In addition we will AL Shop Practice when you grad- you to qualify for profitable em- ployment with ‘an exceptionally bright future. Can You Qualify? To be acceptable for enrollment you should be j mechanically inclined, between ages of 13 and hý 40, have fair education and be able to furnish Character references. GET FREE BOOK Get amazing facts about actual opportunitles for amhitious men in Alr Conditioning and Electric Refrigeration. Our new Free Book describes these money-making op- portunities and tells about our low-cost, easy-pay plan of training. end coupon below, or write for your copy today, stating age and which industry interests you most. No obligation. UTILITIES ENGINEERING INSTITUTE Fetsblishes 400-410 N. Wells St., Dept. 228 Chicago, Ill. SEND THIS COUPON FOR FREE BOOK Utilities Engineering Institute, Dept. 228 400-410 N. Wella St., Chicago, I. - tne big’ opportunitice offered m Alt Conditioning and Elcetrie Refrigeration. I have marked which Interests me most. L] AIR CONDITIONING LI ELECTRIC REFRIGERATION CONTENTS—Continued from page 10 RADIO Machine Jots Code On Tape - - - - - ~ 4 New Giant Antenna For KDKA - - - - 48 The MM Short-Wave Transmitter - - - - 99 AUTOMOTIVE New Tire Irons Aid Mired Cars - - - - 47 Miniature Autos Exhibited - - - - - - 63 Exhaust Gas Made Harmless - - - - - 63 Elevator Garage Stores Auto Under Lawn Of Home - - - - - - - - - - - - 64 “Stiltmobile”? Aids Mailmen - - - - - - 68 Timely Short-Cuts For Motorists - - - - $1 AVIATION Navy Acquires Giant Patrol-Bomber Flying Boat - - - - - - = - - « - - 55 Private Planes And Boats Engage In Sham Battle - - - - - ------ = 6 Aircraft Has Bird-Like Wings - - - - - 64 Speed Up Of Coast-To-Coast Air Travel Shown - - - - - - - - - - -07 Build “Mock—Up” Air Liners - - - - - 67 DEPARTMENTS Problems - - - - = - - - - - - 18 Chips From The Editor’s Workbench - - - 28 Nic Sprank’s Oddities- - - - - - - - 56 Crafts And Hobbies - - - - - - = - 7l MISCELLANEOUS Croquet Game Modernized - - - - - - 37 Builds Odd Sternwheel Boat - - - - - 46 Family Of Three Travels In Home-Built “Cyclemobile”? - - - - - - - - - 4 Scale Model Demonstrates Novel Racing Vessel - - - - - - - - - - - - 84 Photo Lens Registers Rays Predating Dino- saur - - - - - = = - - - = - 57 Compound Irradiates Heat - - - - - - 57 Kiddies Taught Traffic Laws - - - - - 57 Edison Memorial Bulb Ready - - - - - 61 Railroad Tests Mile-Long Stretch Of Welded Track - - - -~ - - - = = = = 6 Artist Makes Wood Pictures - - - - - €7 Welded Home Developed - - - - - - 68 Nail Holds Fractured Bones - - - - - 69 14 Accept Ne Substitutes! Always Insist on the Advertised Brand!

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Puts This All-Purpose LECTRIC ARC WELDER IN YOUR SHOP TEN DAY TR IAL GUARANTEED SOM TEN MONTHS AWAY PROFITS! DO YOUR TO PA OWN WELDING! That’s the modern way to increase income and customer satisfaction. And, it takes only 22e a day to do it, Yes, you get the sensational, ALL-PURPOSE Commonwealth Are Welder, Model 120-FS for only $5.75 down, with Ten whole Months to pay balance out of profits. Now it is EASY for every inventor, laboratory, home workshop owner, garage, repair shop, and factory to afford a complete welding service for manufacturing, maintenance, experimental or repair work. Model 120-FS makes and saves money for you 1001 ways, Repairs gears, brackets, shafts, pump parts, sheet metal, machine "s, cast- ings, stampings, motor blocks, auto frames, body metal. fenders, bumpers, ete, Ideal for making special tools, dies, jigs, fixtures, etc. Works On Both 110 or 220 Volt A. C. Simply plug. into_a 110 or 220-volt. 60- cycle A.C. line, Economical—costs only a few pennies an hour to operate. Often pays for itself on first or second job—yet you have ten whole months to pay ortable—move it anywhere in shop on its heavy-duty, tempered steel Casters, FREE or carry it right to outside jobs in auto, truck, or side-c: Anyone can, weld . with its easy-striking, automatically- wi th stabilized arc. Comes complete with all necessary accessories, Nothing else to Ever buy. Fully guaranteed. Breath-taking y low price!’ Saves and makes hundreds More Than Twenty- Welder and even thousands of dollars. T : N Handles All Welding, Sheet Five Thoasand cod ipee Metal to Heavy Castings use in every section of the Unit Modet 120 TS d a big. 41 0-pound. men very S D size eavy-duty welder, with effici States, and in practically every f. ACCESSORI ES of machines costing many dollars more, eign country. They have been put- and capable of doing exactly the same chased for every welding purpo: Welding cables, elec- work, Welds iron, steel, cast iron. cast urn 1 trie holder, extension steel, and alloys of them. Six instantly and by every type and kind or bu cord. professional Weld. obtained heats handle everything from ness, from the smallest to the Ja e Helmet, supply of fenders and light sheet metal to motor est. The United States Government, assorted welding rods, blocks. and heavy castings. Also EXE " 7 Carbon rod. struc: solderinmz Y g. , Us n Bethlehem Steel Company, Gulf Re E 1 Tol and Meus welding rods. No experience or special fining, American Elevator. Swift n otrs training needed to operate. Simple, Coni- and Company, and scores of other nt eXtra CORE. plete instructions for doing all ki £ nationally-known concerns are on Welding jobs included. MAIL COUPON our list of customers. 'The quality and e v of Model 120-FS BELOW for complete FREE details. are praised in hundreds of letters from ent tic, satisfied users. Get Amazing Details — FREE Send today for amazing detalls about Model 120-FS—at a fraction af tho price asked for others. Learn how, for only C a day, you can own this highly efficient, all-purpose, PROFIT-MAKING weld- ing machine. Send NOW fo. full facts. COMMONWEALTH MFG. CORP. 4208 Davis Lane, Dent. E-52 Cincinnati, Ohio. State---777^7 I| Pien Answering Advertisements Please Mechanic iy en

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Bea Civil Engineer! Le: koe Way It’s Paying Big Cyclopedia os Civil Engineering 7 great volumes. 2,800 pages. 1,600 illustrations. New revised edition a Year—and U by twelve of Amer- “Civil engineers are wanted bw. Enor- - mous amounts are being spent in all mas greatest engi kinds of public Works an nor a dime 1S e — spent unti e engineer S prep: Includes: Surveying, plans. Then He must direct the work. bridges, railroads, It’s a big job and there are not enough 1 - men to go around, Everywhere you g0, ne e E ater Md you see Ead work going on—water and cip g me Sewer systems being built—vast projects water supply, road of all Kinds. Here is Your opportunity building, ete. Spanish Grain Flexible Covers Gold Stamped to get the necessary training Tight at home. These books are complete and simply written so anyone can understand them. Start now on our FREE examina- fion plan. Mail the coupon without ob- igation American Technical Society Dept, C2320, Drexel at 58th St., Chicago —— m — m - — — — X e — — American Technical Society Drexel at 58th St., Dept C2320, Chicago I want to examine the CIVIL ENGINEER. ING Cyclopedia for 10 days FREE. I will gladly pay ihe few cents express, but I to pay uothing for the 7 big volumes return them within 10 days. If Y to keep them I wil send you $2 after the 10 days, then $3 a month un- tll advertising price, $29.80 is paid. we Send latest Edition and Slide Rule. will include a° Srana new, circular slide Name --- Address zme to E d i. AE pocke avaluable: dn (Attach letter stating agé, occupation, Solving all kinds of employer's name and adress and That of at least one business man as reference.) engineering problems. This Man Makes BIG MONEY! "Six years ago I bought a Foley Electrakeen Lawn Mower Sharp- ener and mounted it on a smali truck for a portable shop. First day I took in $13.00 in the afternoon. From then cn I earned from $25 to $30 a day for the balance of the season. The Foley turns out a perfect job and I have the same customers year after year.” H. N. WOODMANCY, Minnesota Free Plan Starts You A BIG OPPORTUNITY is waiting for wide-awake men who want BIG PROFITS and an INDEPENDENT INCOME. I'lenty of busi- ness. We tell you ho ` to get started. No experience necessary —very little capital ne. led. Build a steady, permanent business sharpening lawn mowers by the Foley Electrakeen System. i x» Attachment for grinding axes, hatchets, Special Offer: Knives, ctc., included FREE with Foley Lawn Mower Sharpener on our Special Offer, brings you business the year around. Send postcard today—no salesman will call. FOLEY MANUFACTURING CO. 206-8 Foley Bldg., 11 Main St., N. E. Minneapolis, Minn. Learn to MOUNT Birds... Send Todayfor Free Book Old reliable school (250,000 students) will teach you AT HOME to Mount BIRDS ANIMAL HEADS, FISH and TAN | SKINS and FURS. Write now—at once. SPORTSMEN: £^ nem rowing searcer — every Specimen is valuable. Keep them—save them — mount them. Decorate your den. Fun and fascination, Profits, ou TAN y eg yere light skins and fu ESS LEATHER, BUCK Tore tate! ETC. Bes! method known, but easy end simple. Don’t sell those hides cheap, Tan thern for your own use. Male leather vesta, belts, gloves, ete, TAN FOR OTHERS. TUR- WORK for men and women. Tan and scerfs, capes, coats, mufs, mitts, trimmings. Quickly, easily learned. $40 to $80 & month, even EXTRA MONEY 20 to 550.» month, even EAE pay oR for TAXIDERMY, TANNING AND URW A real spare-time business aod i in every community. If you need extra money, WRI 48 pages, 100 beautiful pictures, tells ALL about Taxidermy, Tanning, Fur-Work, Write Today— this minute for this STRANGE, MARVELOUS FREE BOOK. A postal will do. State AGE, N. W. School of Taxidermy, 4732. Elwood Bldg. WHIZ ELECTRIC TOOL DRILLS—GRINDS—POLISHES—SANDS SHARPENS—SAWS—CARVES A whole shopful of tools In one. Most useful power " tool for home owners, hobby workers, mechanics, etc. Works on: Metals, Woods, Alloys, Pastics, ete. Powerful 110 volt, AC—DC motor. size chuck, Ya” capacity. Pistol Erlp with umb switch. ‘Uses 50 different accessories, stantly interchangeable. FREE! Accessory outfit includes set of drills, mounted 114” grinder, sanding discs, cutting wheels, mounted brush, etc. (Regular value $2) FREE with each outfit ordered NOW. Everything sent postpaid for $6.05 on 30 Day Money Back Trial. PARAMOUNT PRODUCTS CO. Dept. 2-B, 245 Broadway, New York TAKE ORDERS FOR THIS FAMOUS LINE, Make big money with nationally-adver- tised custom-tailored suits and overcoats. eg ot house, noted for its clothes and service, We'll help you. Want active men with personality and intelligence. Write at once. P. H. DAVIS TAILORS, Dept. R, Cincinnati, Ohio MAKE MONEY IN YOUR WORKSHOP Build furniture. auto trailers, canoes, iceboats, cruisers. sailboats and electric refrigerators described in REE BLUEPRINT BOOKLET MODERN MECHANIX PUBL. CO., Fawcett Bldg., Greenwich, Conn. WRITE BE AN ain omnia 89:3 TODAY GOOD PAY. . . AND PLENTY OF OPPORTUNITY Active Men—19 to 50—tralned as Railway and Bus Passenger Trafic Inspectors are in constant demand. Simple, home-study course tralns you quickly and upon completion we place you at up to $135 per month, plus expenses, to start, or refund tuition, Splendid opportunily for ad- A RAILWAY Tancement — Free Tooklet STANDARD BUSINESS TRAINING INSTITUTE. Div. 6102, Buffalo, N. Wo 16 Accept No Substitutes! Always Insist on the Advertised Brand!

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_ Enjoy a Rea Steady Work As nearly all manufacturing—construction— building starts on the drafting table, the drafts- man is one of the first to be hired and one of the last to be laid off. It is his blueprints, his specifications, that give the last word in what the workmen are to do. No article—building or con- struction job is started before the plans drawn by the draftsman have been officially approved. Good Pay The draftsman has been called the Junior Engi- neer which title just about describes his work — position and pay. He combines his knowledge of principles, mechanism and construction details with the ability to draw and reproduce motions and methods on paper. On the average, his salary is con- siderably above the wages of the mechanic and, of course, less than that of the engineer. Li Chance for Promotion Working on plans, helping design new machines or new methods of construction, the draftsman is working directly with the important men of the organization. Consequently he knows what is being considered end planned. It may be the superintendent—the engineer—or even the prospective buyer with whom he consults. Because of these contacts, his ex- perience and knowledge of the business in general he is in an excellent position to be promoted when next there is a good opening, 2 Lessons Free Test yourself — see how readily — * you, too, can learn Drafting Young at 40 Athletes—farmers—and factory and shop work- ers who rely on muscle start growing old even before they reach 40 while office workers—executives —teachers—professional men, in fact, all kinds of brain-workers are just approaching their prime at 40 to 50. Training increases your value at once and continues to help boost your earning power as you mature and as you increase your experience and background for forming judgments of the firm's policies and methods. Don't grow old at 40. Train now for the job you want at 50. 'Training helps you to be inde- pendent—self-supporting. It helps you to enjoy associations that are denied the untrained man. Training helps you to increase your earning power and by so doing to offer members of your family ad- vantages far in excess of what you could give them as an untrained man. Train and enjoy PROGRESS— CON- TENTMENT-—INDEPENDENCE. American School, Drexel at 58th, Chicago =a " ns American School, Dept. DD-228 Drexel Ave. at 58th St., Chicago Without the slightest obligation, send 2 beginning Drafting Lessons and free Bulletin. Pp: ——————————U webesaaunpeueu Slll nguais When Answering Advertisements Please Mention February Modern Mechanix 17

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Editor's Note: not require special research or involve trade secrets, scribed in this issue can also be obtained free upon request. reply. Address: CEMENT FOR IRON AND MARBLE My problem is to find a cement that will enable a sheet of iron to be attached to a marble slab. Can you supply me with a simple formula for such a cement?—Walter Johnston, New York, N. Y. À satisfactory cement for the use you have outlined can be made as follows: 30 parts of Plaster of Paris, 10 parts iron filings, 15 part sal ammoniac. Mixed with vinegar to *»rm a fluid paste, the adhesive is easily applied to the iron and marble surfaces. DRILLING HOLES IN GLASS I am writing you to see if you can supply me with the proper method of drilling small holes in sheet glass. Please advise.—Chester Bush, Anderson, Indiana. Take any piece of steel wire and file it to the shape of a drill. Hold the drill in a flame until it is a dull red and then quench it in metallic mercury. Thus treated, the steel wire will drill through glass very easily. Lubricate the drill with oil of turpentine while using and when the point of the drill has touched the other side of the glass, place the glass in water and drill very slowly. In making the drill do not make the cutting edges too acute. MAKING TYPEWRITER RIBBON INK I am making a toy requiring a typewriter ribbon which I must make myself, due to size. Can you provide me with information as to how to make a good ribbon ink?—-Paul Slusher, Plymouth, Pa. Dissolve 14 ounce of aniline black in. 15 ounces of alcohol and add 15 ounces of concentrated glycerine. Apply the ink to the ribbon by means of a soft brush and rub it well into the ribbon with an ordinary toothbrush. Be sure to stir the ink mixture well before applying it to the ribbon. SOAP FOR CLEANING CARPETS Can you tell me the name of chemicals which, when mixed, will form a good cleaning fluid for rugs and carpets?— Vincent M. Gantt, Hickory, N. C. 18 Your questions will be answered personally and free of charge by MM experts provided they do Naincs and addresses of manufacturers of new products de- Enclose a self-addressed and stamped envelope for Problems Editor, Modern Mechanix Publishing Co., 1501 Broadway, New York City. Commercial rug cleaning preparations are available at small cost, but if you desire to make your own the following formula is rated highly: mix 4 ounces of Fuller's earth with 8 ounces of Pearlash and 1 ounce of turpentine. Make into a stiff paste with the consistency of soft soap. REMOVING FUEL OIL ODOR FROM HANDS Can you tell me how to remove the odor of light fuel oil from the hands?—James Lawrence, Vancouver, B. C. Canada. To remove the odor of fuel oil from the hands, wash the hands in a bowl of vinegar. Rub the hands vigorously in the vinegar aud then wash off with soap and water. AIRPLANE PILOT LICENSE EXAMS Please inform me as to the proper procedure to take in acquiring a student pilot's license. Do I have to have the license before 1 can take any instruction in aircraft?— Walker Bartlett, Hewlitt, L. I. The Bureau of Air Commerce rezulations concerning the issuance and qualifications for pilot licenses (incidentally they are no longer termed licenses, but “certificates of com- pelency’’) have been greatly changed within the past few months. Direct your inquiry to the Bureau of Air Com- merce at Washington, D. C., or consult the manager of the airport at which vou plan to take flying lessons. MAKING LUMINOUS PAINT Kindly send me a formula for making a luminous yellow paint.—Alexander Egbert, Philadelphia, Pa. The following formula will provide a luminous yellow paint: 100 parts (by weight) of strontium carbonate, 30 parts of sulphur. 2 parts of sodium carbonate, 0.5 parts of sodium chloride. 0.2 parts of manganese sulphate. The materials must be heated for about one hour at a tempera- ture of about 2,375 degrees Fahrenheit.

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21 Contributing and Consulting Editors: great book. By placing your reserva- 12 VOLU MES IN ONE W. K. Green, Amherst College tion now, however, you may have it at —Astronomy; F. T. Morse, of the special pre-publication price of only

The contents of more than 12 average-size volumes. Virginla—Mechanical Engineers 95-4 s Here is a brief outline of some of the Sub]ects: ing; L. L. Smail, Lehigh U., | 5? e payable in easy monthly install- » , —Mathematics; R. M. Fleld, nens CHEMISTRY: Chemleal elements—symbols, atomic Princeton — Geology; R K number, atomic weight, donsit. hardness, melting id ayi s xd point, common reactions, orcurence im nature, pro- Strong, Rose Polytechnic— READ IT FREE duction from ores, uses in in Compounds, Chemistry; A. W. Lindsey, 1 manufacture and use. Organ 1 l Denison U.—Zoology; L. D. products. Agricultural cher n Weld, Coe Colleze—Physles; R. Send no money now. We will send ihe Scientific PHYSICS: Mechanics. heat. light. sound, electricity. S. Mueller, M. D., Columbin Encyclopedia to you Tor free examination. Read it, magnelism, X-rays, ele., ec Tedicine; R. M. Wheldon, use it for 10 days. ‘Then pay the special low pre- I.I. T., Botany; and many publication price of only $8.95 in easy monthly in- MATHEMATICS: Arithmetic to 4 trigonometry, calculus, differe 2 stallments, or return It and you will not be obligated special emphasis on application in the least. Mail the coupon at once. ASTRONOMY: Covers the entire subject. p locates each im- ——— — — Ó— —À — —À — — —À —À — — —À — —— portant constellation jn the sky. Planet: telescope, spectro- TE | MAIL THIS COUPON - SEND NO MONEY |

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INVENTORS Whether YOUR Invention Requires ECHANICAL a PATENT : “| A PROCESS OR ACOMPOSITION | METHOD PATENT | Our Patent Service Can Help YOU! Securing brond patent protection for an invention requires specialized skill. Our business is confined exclusively to Pat- ents, Trademarks and Copyrights. We have served inventors throughout the world for over 62 years. From the mo- ment you send us a sketch and descrip- tion of your invention, we take all the detailed work of the complicated patent Process off your hands. Every member of ður firm is a U. S. Registered Patent Attorney. Take These Steps te Secure Broad Patent Protection FIRST you will want to know exactly how the Patent Laws protect you, how much the cost will be, how to sell vour invention. Our free books answer hun- dreds of questions ahout Patents and how to sell your invention. SECOND, we will make an examination through per- tinent U. S. Patent Office records. Then we can tell you whether in our experi- enced opinion you can obtain a patent. THIRD, we will carry your case through the patent office with all possible speed, consistent with obtaining for you the broadest possible patent protection. Finished Models or Drawings Are Not Necessary Don't go to the expense of a costly model or finished drawings. All we need now is a sketch and description of y^ur invention. Our “Certification of Invention” illus- trated on the right is valuable to you because after it has been properly filied out, signed, dated and witnessed, it can be ofiered as evidence in support of your claims should some other person endeavor to prevent you from protecting your In- vention by claiming prior rights. It is free. Send for it now and fill It out at once. FRE : a ON" no. o OUR DEFERRED PAYMENT PLAN We have helped thousands of Inventors with our deferred payment plan. This plan is very flexible. You may spread the cost of your Pat- ent over several months in convenient payments. The most important step is to GET STARTED. We can help you oven though you cannot pay the full cost of your patent NOW. Money Making Inventions Are Often Very Simple Don't be discouraged if your invention isn't complicated, Many of the greatest money-inaking inventions are ex- tremely simple. Then, too, your invention may be vai- vable even though it is very similar to an invention already patented. An improvement over some “gadget” already on the market may be patentable. Our free books go into this subject thoroughly. Important Things to Remember Secrecy in Patent matters is of the utmost ime portance. Your case will be treated with strict confidence from the moment you entrust us with your secret plans. We never buy inventions or sell them, Our only business is to serve inventors efficiently, quickly, and CONFIDENTIALLY. C. A. SNOW & CO. Registered Patent Attorneys Since 1875 SNOW BUILDING, WASHINGTON, D. C. SEND FOR THEM TODAY! C. A. SNOW & CO. 3010 SNOW BUILDING, WASHINGTON, D. C. Gentlemen: Send me your free handbooks for inreniors by return maii. No obligation on my part. Name Address I | | i i i | I | l Don’t Delay Write Today! State. City When Answering Advertisements Please Mention February Modern Mechanix N NM

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Brand New Radio Section, Pub Address Systems Covered Here’s great news for anybody interested In Electricity, BRAND NEW edition of Applied Electricity including Diesel Electric plants brought right down to date with every NEW Electrical subiect fully covered. 10 big Volumes and all shipped FREE for examinatlon. BIG FIELD! Big Demand! For Men who understand electricity Beginners Bi Pa V are urgently needed right now in g ig y: thousands of industries. s Autos. airplanes, machine shops—practically eve: in- dustry depends on electricity and men who know this subject make big money. Pleasant, fascinat- i work, easy to learn and do; learn quickly with these books. Send coupon for a set for TREE examination and see for yourself. A year's consulting membersh!p in the American Technical Socies ty now given to all readers of this famous Cyclopedia of Elec- tricity. Many say, ‘That’s worth more than cost of books.’’ AMERICAN TECHNICAL SOCIETY Dept. 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Works Off 110 Volt Electric Light Circuit == $ —" Pu ^" For this unheard cf price, you can get the marvelous Dynamic Super-Charged Welder complete—all ready to plug in your light socket —nething else like it has ever been made. This new Dynamic Super-Charged Welder is a radi- cal departure from accepted welding practices. Jt will do the work of welders selling for much higher prices—such as cylinder blocks, bumpers, tanks, etc., and at the seme time will solder and braze on the lightest material—and the cost is not $200.00 or $100.00—think of it, the complete price is only $19.73. These pictures show how easy it is to operate the Dynamic Super-Charged Welder, A ten year old boy can do a swell fender rcpair job—an Inexperi- enced man soon can do all kinds of welding. WELDS CYLINDER BLOCKS, FENDERS, AXLES, BODIES, BUMPERS, FARM MACHINERY, CAST IRON RADIATORS. ETC. With the Dynamic Super-Charged Welder, a man without previous welding experlence can make for himself as much as $5.00 on a repair job that can be done in less than one hour. Many welders make as much as $15.00 to $20.00 a day. Despite its serviceability, the Dynamic Welder js light and easily portable—can be carried around by hand and set on the running board of any car you are working on. DYNAMIC SUPER-CHARGED Does Both Metallie Arc and Carbon Arc Welding. Can be used efficiently on both types of welding, The cost of using the Dynamic Super xed Welder is amazingly low—costs only a an hour to operate. It Is built so strong repalrs are practically unknown—you'll never have to worry about them. It cools so efficiently that you can use it continuously without, ever having to stop in the midst of a job to let it cool down. AGENTS WANTED! can make factories, mechanics, janitors and maintenance men Do you want something easy to sell? You g profits introducing to garages, WORKS ON !RON, STEEL, TIN, BRASS, COPPER AND ALL OTHER METALS. With this welder you ean work on all kinds of metal—nothing will stump you—you can tackle. anything and in no time at all you will be alle to do finished repair jobs that will do credit to an expert, Once you have the Dynamic outíit, you are all set in a profitable welding business of your own—you boss it yourself. the new Dynamic Super- 3 1 Gentlemen: — —— — À— — 1 — 9À — «o — o o — -— A A € : DYNAMIC WELDER CO., 2225-BG Silverton Rd., Chicago, Illinois. Charged Welder—we'll let you try it for ten days at our risk so you can be convinced of the immense sales possibilities, Get our big profit plan and ten day trial offer. Just send coupon below and mail it TODAY. You may send me full particulars on your big profit plan and 10 days trial offer. DYNAMIC WELDER CO. | ^ — 2225-BG SILVERTON ROAD, CHICAGO, ILL. I NER RR EIER Stste- ae oe » When Answering Advertisements Please Mention February Modern Mechanix 25

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TURN SPARE HOURS INTO CASH! No soliciting! No canvassing! We show you how to make big money decorating fast-selling Giftwares, We start you with the big $10 Artist's Outfit shown above, We supply you with $150 worth of Giftwares free of extra charge and show you how to dis- pose of them without leaving your home, We give you 29 Tested Plans for making money, One Fireside Member says, “I made $100 on furniture in one week.” Another writes, ''My sales were $500 for 5 weeks, This is my first year." R. M. P., of Ill., says, '' did $3,500 worth of business last year and over $12,000 this year.’” D. W., New Mexico, reports, “I would not take $1,000 for my Course."* No Experience Needed You too may have a splendid income opportunity with Fireside, No tiresome study, You learn by doing, No artistic ability neces- sary, Our easy 3-Step Method makes the work easy to learn and easy to do and fits you to make S$ good money practically from the Start, Quick Sales in Your Home No need to quickly fu the Giftwares you can t No Cost Plan Send coupon for d plan that pays for Course besides putting profits in your pocket. D pon now while openings for new members are still being offered. FIRESIDE INDUSTRIES Dept. 142-B Adrian, Mich. Fireside Industries Dept. 142-B, Adrian, Mich. Send me FREE Book on Home Deco- yating for a big steady Income. Also details of plan that will pay for my Course and give me big profits be- || l [ | sides, l l i I NAME ADDRESS I CITY..... circular No. 5, | 201-204 Manchester Bldg. HOW To DRAW FROM The NUDE Learn how art is really taught in the studios of Paris and New York. Send for FREE ilustrated brochure describing in detail a great new plan that brings real studio methods, with actual professional model poses, to your home or office. This plan, "How to Draw From the Nude," shows by text and illustra- tion, how art is studied in “life” classes, It’s great fun learning art this way. You will also receive details of our FREE offer of "Making Art Pay," a guide to art markets and “tricks of the trade." No cost or obligation—write to NATIONAL LIBRARY PRESS, Dept. K. 110 W. 42nd St. New York, N. Y* Make money in advertising. Prepare quickly during spare time. Also emru while you learn. No experience necessary, New, easy method. Nothing eli like it. Send at once for free booklet—''Win Success in Advertising,’’ and requirements, No obligation. Page-Davis School of Advertising 3601 Michigan Avenue, Dept. 2052, Chicago, Illinois, U, S. A. WANTED — MEN to cast Christmas Goods, 5 and 10c Novelties, Toy Autos, Ashtrays, etc. Can be done in any spare room, basement or garage and no experience necessary. A rare oppor- tunity to devote spare or full time to profitable work. Write Dept. 2. METAL CAST PRODUCTS CO. 1696 Boston Road New York City ON FUEL COSTS. A. = zx ©) Convert your car to burn Diesel oil. Save up to 70% fuel costs, Cheap installation. Wonderful performance, Proren factory method. Different and better, Costs nothing to investigate. Write for free HARRINGTON COMPANY Portland, Oregou ‘Learn Profitable Profession: „in OO days at Home — Salaries of Men and Women in the fascinatt TO fession of Swedish Massaga run as high as $40 to \ $70 per week but many prefer to open their own ol- i fices. Large incomes from Doctors, hospitals, sani- 4j! tariums and private patients come to those who quallfy through our training. Reducing alone offers rich rewards for specialists. Nar for Anatomy Charts, sample Jes- Bon sheets and booklet—They’reFREE, J THE College of Swedish Massage 1601 Warren Blvd., Dept. 258, Chicago (Successor to National Collegeof Massage) ! Save Mouey—Fit Guaranteed We send a large assortment for you to select from in your own home. Over 100,000 on hand at all times, All sizes, shapes, coloring. Finest quality obtainable——at substantial saving. color guaranteed, Old reliable firm tomers, that tells how we fit eyes for custom DENVER OPTIC CO., Satisfactory fit and rith thousands of regular cus» Send name of anyone who wears an eye for FREE BOOK all over the world by mail, 1202 University Bldg., Denver, Cola, Accept No Substitutes! Always Insist on the Advertised Brand!

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Sind. ELECTRIC ARC WELDER ew Works Off Any Storage Battery A or Ordinary Light Socket. . This New Electric Are Welder is made possible by the invention of a low voltage carbon. Auto batteries may be used without = removing from car. Uses about SIS d same current es four headlight bulbs. Can be ) used on 110 Volt electric light socket or 32 Volt electric light plant by using a Trindl Con- verter'in place of battery. Broken parts are SIMPLY MELTED TOGETHER by the j white HOT electric arc, in just a few sec- |Z onds. Produces about 7,000 degrees heat. i x HOTTEST FLAME KNOWN d ~ Melts iron and steelin-[7z N stantly. Welds fenders,| AGENTS radiators,holesinbodies| Men with cars to and milkeans, tanksand] Bel! mechanice i repairmen and brazes broken castings. farmers, facto- WORKS onANYTHING| ries. radio and ron,steel,copper,brass,| B&ttery shops. tin or galvanized metal.| monetration Permanente) airamade males gales, p oralmost nothing. Us: To by factores in many op- Write TODAY. erations Positive rnoney back guarantee, TRINDL PRODUCTS, 2229-YZ Calumet Ave.. Chicago, ill. Raise giant patented mushrooms! We supply materlals und instruct with pictures. Our 25 Coast-to-Coast branches buy all crops, Big FREE book, photos tell if your cellar, shed, barn, ete., suitable, Write today. (Established 1908.) UNITED MUSHROOM COMPANY 3848 Lincoln Ave., Dept. 317, Chicago EARN MONEY «s WE SHOW YOU HOW! 5 Simplified plans make old auto generator light buildings, play radio, operate washing machine and other motors. Sell friends and neighbors. Dime brings complete plans, and 1938 farts catalog. LEJAY MFG. CO., 414 LeJay Bldg., Misneapolis, Minn. EARN MONEY Make Color-glazed Concrete Products New, perfected low cost method. No molds, power or costly tools. You build your own equipment from plans we furnish. Experience not necessary to make color-giazed concrete garden pottery, statuary casting, giftware—in home or shop—to earn money. MEN—Send 10c TODAY for booklet, colonplate, No obli- detalls of this money making business. Eation. NATIONAL POTTERIES COMPANY Room B, 13 W. 26th St. Minneapolis, Minn. WORLD'S SMALLEST RADIOS Just a handful—Wt only 2 lbs.—Size 312x5”—4 tube Derformancel Midget BUILT IN LOUNSPEAKER and AERIAL—Requires no ground—Hi-efflclency?cireuit and juality parte. Has Broadeast, short wave and foreign banc. mple to operate—durable—trouble free, Ideal Radio for ffice, Apts.. Bedrooms, College, Camps, Traflers, Tourists, etc, B. has batteries inside case for use on farms, boate, autos, etc. Electric model uses „C.D.C. Either model kit of parta for $6.49— Wired ard checked 50c extra 11! SENI complete ready to llsten! Beautiful breakproof cabinets. State Color. ND ONLY $1 and pay postman balance on livery. (Bat- terles for battery model 51 ra.) Free catalogue listing 100 other radios at factory price. Order n aranteed. TINYTONE RADIO CO, M-2 KEARNEY, NERRASKA Go 1o High School at Home o You can secure a high school education in your spare time by studying the new courses prepared by the International Correspondence Schools. These courses are equivalent to the courses given in resident high schools. They have been specially arranged for men and women who wish to meet college entrance examinations, to qualify for a business position, or to make up the education they missed in past years. The lessons are easy to understand and you will make rapid progress because you will be im a class by yourself and you will study under the guidance of instructors who are sincerely interested in you. Just mark and mail the coupon and we will gladly send you interesting free booklets describing the High School Courses of the I. C. S. or any other subject in which you are interested. ORRESPONDENCE Box 2318-P, Scranton, Penna. Without cost or obligation, please send me a copy of your booklet, “Who Wins and Why,” and full particulars about the subject before which I have marked X in the list below’ O College Preparatory Course D High School Commercial Course [O High School English Course O High School Vocational Course O High School Agricultural Course BUSINESS TRAINING COURSES O Business Management D Service Station Salesmanship D Office Management D Business Correspondence O Industrial Management D Lettering Show Cards D Signs D Traffic Management D Stenography and Typing LI Accountancy and D Civil Service C.P.A. Coaching G Mail Carrier D Bookkeeping C Railway Mail Clerk O Secretarial Work D Grade School Subjects O Cost Accountant D First Year College O Salesmanship O Advertising [D Illustrating U Spanish D Wallpaper Decorating D Cartooning Li French Salesmanship D Lumber Dealer TECHNICAL AND INDUSTRIAL COURSES O Architect O Plumbing O Heating D Contractor and Builder D Air Conditioning D Structural Draftsman O Sheet Metal Worker D Structural Engineer O Steam Engineer D Electrical Engineer D Civil Engineer O Reading Shop Blueprints D Surveying and Mapping O Telegraph Engineer D Refrigeration CG Telephone Work Dn R. Locomotives O Air Brakes DR. R. Signalman D Highway Engineering D Chemistry O Pharmacy D Coal Mining Engineer D Navigatioun D Boilermaker O Textile Overseer or Supt. D Cotton Manufacturing D Mechanical Engineer D Mechanical Draltsman D Machinist [D Toolmaker D Inventing and Patenting [3 Patternmaker D Heat Treatmert of Metala D Bridge Engineer D Gas Engines O Diesel Engines D Woolen Manufacturing O Agriculture O Marine Engineer O Fruit Growing D Radio Age.. [D Aviation Engines D Automobile Mechanic Name. Adcress. Occupation. gu df you reside in Canada, send this coupon to the International Correspondence Schools Canadian, Limited, Montreal, Conaua When Answering Advertisements Please Mention February Modern Mechaniz 27

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Constructed from MM plans by Charles Nowak, this “Buddy” sailboat presents a pretty picture as it cruises along. Sail area is 300 square feet and mast stands 26 feet high. A LETTER describing a trim looking boat, con- structed from MM plans, won first prize of $5 this month for Charles Nowak, of Milwaukee, Wis. He writes: Dear Editor: Enclosed is a photo of "Buddy," which I built from plans in your "How To Build 20 Boats" book, There are three "Buddys" here in Milwaukee, but mine is the fastest. (Proved during races.) The boat has proved to be a good rough-weather sailor, taking high seas in a very satisfactory manner. 1 use 400 pounds of ballast and the total weight of the boat is about 2,900 pounds. Charles Nowak. We compliment Nowak for the craftsmanship evident in "Buddy's" construction. The photo of the craft under full sail undoubtedly will inspire many other MM readers to construct a boat for use this coming summer. 28 An award of $3 was sent to Clyde Kempf, of Canton, Ohio, for his letter in which he says: Dear Editor: Here is a snapshot of my "Runlite" trailer, which I built from plans appearing in your book "How To Build Trailers." I use the trailer for fishing and hunt- ing trips and find it very practical. "Runlite" was very easy to build and I have received plenty of compliments on its appearance. Keep run- ning good workshop plans in MM. Clyde Kempf. Judging from the photo, Kempf's trailer is well equipped—a veritable "camp on wheels." *okok Readers are urged to accompany their letters to the Workbench with clear photos. Many letters received must be rejected for entry in the monthly contest simply because the photos sent with them are poorly taken, preventing reproduction. Gk x An interesting letter received from Mike Liptak, of St. Paul, Minn. was awarded a $3 prize. He Says: Dear Editor: Enclosed is a photo of my brother and I holding our five-foot gas model airplane. It represents 100 hours of work. During a contest we filled the model plane's motor with gasoline and it flew out ef sight, but was returned to us the following day. We hope to see more gas model plans in future issues of MM. Mike Liptak. Mike sent us a clipping describing the flight during which the gas model airplane was lost and home- f to make hunting MM plans were used, Fully equipped with camping P para ae pl this lyde built “Runlite” trailer enables and fishing trips in maximum comfort. M Modern Mechaniz

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all we can say is that the model certainly turned out to be a "flying fool," having made more than 40 good flights since its construction. ok ok Midget racers still appeal to a majority of MM craftsmen and a letter from William Walker, of Akron, Ohio, describing his home-built racer was awarded a prize of $3. The letter reads: Dear Editor: I am sending you two photos of my midget racer, which I built from plans in your "How To Build It" book. The car does 40 m.p.h. easily and averages about 40 miles per gallon of gasoline. My racer is powered with a single cylinder motor- cyc'e engine and boasts a three-speed transmission as well as internal brakes on the rear wheels. I have driven the racer about 500 miles and didn't encounter the slightest trouble. I am a constant reader of MM and enjoy every issue. Your workshop projects are excellent. William Walker. Midget racer fans, we are certain, will agree that Walker's tiny car is a "winner" as far as appearance is concerned. Congratulations for a job well done, Walker. From far away Australia came a letter written by Donald A. McBean. Awarded a $3 prize, the letter reads: A speed of 40 m.p.h. and mileage of 40 miles on a gallon of gasoline is claimed for his home-built midget racer (top) by William Walker. Lower photo shows front view of car. Dear Editor: You may be interested in the enclosed photo of the good ship "Mayilower," which was built to MM plans. Your plans and directions certainly are easy to follow. Ship modeling is certainly a test of patience when you have to make every part by hand. Ready-made paris are not obtainable in this country. Donald A. McBean. A beautiful model, McBean. Congratulations! ae ee Another letter Mike Liptak and his brother proudly hold the five-foot “gas”? powered model airplane they constructed. The model fiew out of sight during a contest, but was returned to the boys again, February, 1938 which wasawarded a $3 prize in this months Work- bench contest was received from John S. Phill of Belfield, N.D., who wrote: Dear Editor: I am enclosing a photo of a built- [Turn to pege 31] Donald McBean’s model ‘May- flower,” built to MM plans. 29

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“PAY AFTER GRADUATION" Don't let lack of money stop you from sending in the Coupon, I'm rea take you into my bic shops, give you 12 weeks of COYNE ind you won't have to pay your tuition until Sixty days after gular 12 weeks training period ends and then you have over a Year to pay the balance in small monthly payments, I'm willing to to this because so many of my successful graduates have proved that thelr increased earnings with COYNE Training make it possible to easliy repay the loan. REAL OPPORTUNITIES FOR THE RADIO TRAINED MAN Prepare for jobs as Designer. E 3 maa and in Servie o Broadcasting Station — a eless as a Talktng Pleture or Sound pert for fascinating, WELL PAID JOBS] 12 WEEKS’ SHOP TRAINING AT COYNE IN CHICAGO —YOU DON'T NEED ADVANCED EDUCATION OR EXPERIENCE At COYNE you "LEARN BY DOING'' or equipment similar to what io will work on when you take a job. You get your Practical Traln- ng by ACTUAL WORK on a great outlay of Radio, Broadcasting, Tele- vislon, Talking Picture and Code equipment. TALKING PICTURES — TELEVISION Talking Pictures and address systems offer preat opportunities to the trained mi. Television is the great new branch of Radio w : now belng developed very rapidly, Be ready for your chance i vision. At COYNE you are trained on rdal vision equipment. ELECTRIC REFRIGERATION Training Included WITHOUT EXTRA COST This combination Training (Radio and Refriger: be of great value to you. Whether yon go into busin E ob ‘working for a [tadio Sales and Service C: ou aré trained in servicing Electric R be profitable Gd Qu. Many Radio Manufacturers also c Refrigerators and men with this combination trai ore valuable to these employers, You can NOW get t. nout extra cost, spare to fill a job as This combination training will_erable Tustallation and Service man, Shop ‘Te er, Assembler, In- Spector, ete, You will learn about v. compressors, con- densers, temperature control device iic and expansion valves. This tralning is in addition to the r lar radio tralning which Offers so many opportunities today. PART TIME WORK WHILE LEARNING Speclal low room and bpard rates for C My Employ- ment Department helps you to ect a p to cover ving: expenses, You get employment help afte e, SEND COUPON FOR DETAILS Free “COYNE Opportunity Book'" containing pictures c? m: hi Bnd ft! details of my amazing Offer wlll be sont to you. $ Shops H. C. LEWIS, President Radio Div., COYNE ELECTRICAL SCHOOL 500 S. PAULINA ST., Dept. 28-1H, CHICAGO, ILL, a ip E ane — SDREDS of Opportunities = 2 en alking Picture and Tuvie- =- eD Bu D op p - See Sues eR eB Sseeres, H. €. LEWIS, President, Radio Division, Coyne Electrical School, 500 S. Paulina St., Dept. 28-1H, Chicago, III. Dear Mr. Lewis: Send me your Blg Free kadio Book and all de- tails of your Special Introductory Ofer — and your plan where I can pay my tuition in easy monthly payments after I graduate, CELLE I L i] Was aa m m m m C m 30 Accept No Substitutes! AIR CONDITIONING and Refrigeration Trial Lesson A fast growing field of opportunity. Trained men are needed. Learn the easy C.T.C. way, AT HOME IN SPARE TIME AT LOW COST Write today for FREE TRIAL LESSON CHICAGO TECHNICAL COLLEGE 8317 Tech. Bldg., 118 E. 26th St, Chicago, Iinolg If you can go away to college to learn Air Conditioning, Engineering, Architecture, Drafting, Electricity or Radio, Send for FREE Blue Booz, MAN IN EACH TOWN To Plate Auto Prats Reflectors, Bicycles, Fixtures, Mirrors, by late method. Simple pla» ct munutaeturingz at home starts you IN GOOD PAYING Write today for FREE particulars and proofs. BUSINESS. GUNMETAL CO., Ave. P. Decatur, til. For 30 Days Reading No Money Down—Actual Crime Cases— If Yow Act Quick! We will send you this stirring book on Crime Detection, Secret Service and Idene tification Work for 30 days free reading. Send no money. If you decide to keep it, then send me only $1.00. If not, return it. WRITE TODAY. Liter. ature will be sent only to personsstating their age, Become an expert photographer Get into this fascinating field. For pleasure or career. Our famous method of personalized instruction will make you an expert in Com» mercial, News, Portrait, Advertising, Candid or Motion Picture photos graphy. Blg money-making opportunities! Personat Attendance and Home Study courses, 28th year. Free booklet. NEW YORK INSTITUTE OF PHOTOGRAPHY New York City 10 West 33 St., (Dept. 153) AT HOME You can learn by our modern and original system of instruction every part of the Watch repairing Trade at home. You can earn money white learning and prepare yourself for a well paying positlon or start in businesa after completing our course of instruction, | Good watch repalrers are in demand and generally earn very good salaries. For par» iculars apply to the WISCONSIN SCHOOL OF WATCH REPAIRING 524 E. Mason St., Dept. €, Milwaukee, Wig. R COLLEGE -EAST ST.LOUIS, ILL= Offers you college education majoring in aviation Four courses lead to B. S. degrees in Professional Flight, Aviation Operations. Aviation Mechanics. Aeronautical Engineering. 100 acte airport. 14 buildings, 33 in faculty. 302 enrolled for Fall term, 6,400,000 miles fight tralning. 1,562 planes, 538 engines repalred and rebuilt in shops. Graduates with all leading aviation companies, Dormitories, dining hallonield. Spring term Mar. 28th, Catalog. Write EGISTRAR, DEPT. MM-2 Tith YEAR PARKS AiR COLLEGE EAST ST. LOUIS, ILE, Always Insist on the Advertised Brand!

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Editor's Workbench Chips [Continued from page 29] Resembling an airplane fuselage in appearance, this novel windcharger was built by John S. Phill, of Belfield, N. D. Top photo shows how moving the wheels retracts generator. up wind generator device I constructed. semblance to an airplane. When it is desired to stop the device, the wheels can be moved back, tilting the generator and propeiler by means of cables, Unlike the Indian sketched on the charger, I am a "paleface" cowboy. Note the re- John S. Phill. Se oe Reader Phill certainly selected a novel mount- ing for his wind generator. Any day now, we'll be expecting to see someone send in a photo of a wind generator like Phills to which a wing has been added to heighten the illusion of a plane in flight. Don't forget that MM awards cash prizes every month for the best photos and letters received describing completed projects made in home workshops. Take several clear photos of your latest project, write a short description of it, and send it along to the Workbench. Your entry will receive careful consideration and you may be one of the winners of next month's awards. ww A list of addresses of manufacturers of items mentioned in MODERN MECHANIX will be sent to any reader upon receipt of a stamped, return envelope, IMPROVES YOUR APPEARANCE 100% Have that healthy T. ^I e that Men and Women Admire! ys the first impression that counts! Get that healthy, vital appearance that opens the door to success! Many a man has lost his big chance because his appearance didn’t "click." Social as well as business success depends on your looks . . . and the pale, pasty-looking chap won’t get to first base. Now a daily “sun bath” in the privacy of your own home, will keen you looking like a Million Dollars—and feeling as physically fit as you look? MU LOOK SUCCESSFUL—BE SUCCESSFUL! WE ^ good, healthy coat of tan has a surprising effect on your ap- pearance, Salesmen find their sales actually inerease after they have acquired a real bronze zan? And you will become more popular, for women, too, admire that healthy outdoor look! IMPROVES HEALTH AS WELL AS APPEARANCE! @ Frequent exposure to the ultra-violet rays of the sun tones up the entire system, stimulates tne body into energy and vitality, increases aland activity, builds up resistance to colds , . , and aids in clearing up many skin diseases. 4 TIMES AS POWERFUL AS SUMMER SUN! Bi You know what a glorious tan your skin would acquire if you could spend an hour every noon sun-batling, The Health Ray Sun Lamp has been tested by the well known Electrical Testing Laborztories of ew York, Their report indicates that this inexpensive Sun Lamp rives the same amount of beneficial ultra-violet rays in I5 minutes in your home that you would get in one hour's exposure to the mid- INEXPENSIVE HEALTH INSURANCE FOR EVERY MEMBER OF YOUR FAMILY W Build up resist- ance and vitality. Insure yourself against illness the sunshine way! b FULLY GUARANTEED! MAKE THIS FREE TEST! Test this lamp at our expense NOW! Compact, easy to use, tested and approved . . . it is yours for 7 days FREE trial! This genuine carbon-are lamp, fully euaranteed by The Healih Ray Mfg. Co., Deep River, Conn., will he one of the greatest health investments, you evec made, \ f H HEALTH RAY MFG. CO., INC. 152 Elm Street, Deep River, Conn, 1 (Check below for free iiterature or Sun Lamp) 3 1 taiis of FREE trial offer. fe ! Send Ide Lamp at once. I enclose $1. In 7 days I - wil either pav $6.95 or return the lamp and receive my i 1 I Li LIC dollar back. ee Copyright Deep Rt When Answering Advertisements Please Mention February Modern Mechanix 31

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) TOAPRACTICAL UNDERSTANDINGOF — ELECTRICITY @ AUDELS HANDY BOOK OF ELECTRICITY For Engineers, Electricians, Students and allinter- $ e, ested in Electricity. A quick, simplified, ready eu. reference, giving complete instruction and practical information. Easy to understand. A reliable au- thority and a handy helper that answers your questions. @ INSIDE TRADE INFORMATION ON The Rules and Laws of Electric- ity-Maintenance of Machinery- A.C.and D. C. Motors--Arma- ture Winding and Repair-Wir- ing Diagrams House Lighting ^ Power Wiring--Cable Splicing^ Meters Batteries^" Transformers + Elevators ve Electric Cranes « Railways- Bells Sign Flashers-- Telephone--Ignition--Radio Prin- ciples» Refrigeration- Air Con- ditioning--Oil Bumers~Air Com- opressores W elding: and many Modern Applications explained. so i you can understand. 1340 PAGES To get thisassistance for yourself, simply 2600 ILLUS. fillin and mail the FREE COUPON below. BUSREBEREEEENERENESEUZSRUESSEENNRNHEREREREREESEBRE AUDEL & CO., 49 West 23rd Street, New York m Please send me ‘‘Audels Handy Book of Practical Elec- Wtricity’’ for free examination. If satisfactory, I will send A Ho $1 in 7 days, then $1 monthly until $4 is pald. Otherwlae wi will return it. E Name. m a B Addres: FH a" Occupation u M. M. AiR CONDITIONING is the next big indus- try. Mark that pre- diction! Its oppor- tunities are as big in winter as in sum- 3 mer. Plumbing and heating engineers must know Air Conditioning —the field in its broader aspects invites ambi- tious men. And a new, up-to-the-minute course on Air Conditioning now offered bv the I. C. S. will help you qualify for advancement in this new field. Full information — free. BOX 2320-P, SCRANTON, PA. Explain fully about your course in thesubiec: marked X: OL AIR CONDITIONING D Chemistry O Accountancy O Radio D Advertising D Aviation O Electr Engineering D Refrigeration. U Inventing & Patenting D Architecture D Drafting D Show Card Lettering L1 Good English Big cash profits! Full or spare time. 4 Over 250 household necessities — things peonle must buy. Proven fast sellers; NEW FORD SEDAN OR $500 CASH BONUS BESIDES YOUR WEEKLY EARNINGS. I’ll show you how to start earning very first day; send you every- thing—Rig Display Outfit and quick cash plans— no money risk. Detalls FREE. Just mail postcard. Albert Mills, 4910 Monmouth Ave., Cincinnati, Ohio. 32 THE ATLAS HAS EVERYTHI rd . New FREE CATALOG All who see the Atlas pre- cision lathes and other shep equipment are amazed at the power, versatility and extra features of these modern ma- chine tools, See for yourself before you huy, Send for new 1938 Catalog today, ATLAS PRESS Co. 252 N, Pitcher Street Kalamazoo, Mich. Write for free booklet describing '*107 Plans for J Operating a Successful Business of Your Own". " Make from $20 to $100 a week starting in spare time at home. No peddling or house-to-house selling. Booklet sent free, and without obligation. Write for B your copy today. ELITE PUBLISHING CO. 214 Grand St. New York, N. Y.i f Dept. G No JOKE To BE DEAF -Every deaf person knows that- Mr. Way made himself hear hia watch tick after being deaf for twenty-five years, with his Arti- ficial Ear Drums. He wore them day and nigh "They stopped his head - : noises. Theyare invisible P endcomfortable,nowirea or batterles. Write for TRUE STORY. Also Ñ booklet on Deafnesa, Artificial Ear Drum THE WAY COMPANY 741 McKerchey Bldg. Detroit, Michigan ENTORS. BE SUCCESSFUL ` Read Invention & Finance—it’s your chance to.make money, Two | year subscription $1.00 entered upon promise to pay on receipt of first copy. Place your order by eutting out and mailing this advertisement. INVENTION & FINANCE MAGAZINE $0-H WALL ST., NEW YORK,N. Y. YOUTHFUL Enjoy the vigor that comes from relfeving pressure on Spinal nerves. 15 glorious minutes on Pandlculator gives applianee. Send f: 3 1 | PANDICULATOR CO. 416 Newman i Accept No Substitutes! Always Insist on the Advertised Brand!

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MOTHER-CAN'T 1 ET NO, CHARLES - -ruAS E 69^ 4 CONDEMNED AT 17! EVEN RIDE A TOO MUCH EXERCISE 3 Yes—at 17 years of age I was condemned to the life of a sissy! I couldn't even ride a BICYCLE FOR A BOY IN : bicycle! I weighed only 97 lbs. I had no health, no muscle, no fun or good times ANY MORE ? YOUR CONDITION ! E À THEN my amazing discovery won me the tit 1 now hold: TODAY — “THE WORLD'S MOST PERFECTLY DEVELOPED MAN”! HAT'S all I ask. Give me 7 DAYS, and I'll show you flesh-and-muscle PROOF —in your own mirror, right at home— that I can make you a NEW MAN! I don't care how skinny or flabby you may be. You can't be worse off than I was! My mother forbade me to even ride à bicycle! I was the laughing stock of every fellow in town. Afraid to defend myself, too puny for sports, too ashamed of my skinny carcass to wear a bathing suit! THEN I discovered the amazing secret that made me champion— that won me the international title, “The World’s Most Per- fectly Developed Man"! NOW I AM READY TO TELL IT TO you! How to Get a Perfect Build Without “Apparatus” as he looks TODAY. This mag- nificent picture is taken from an aclual, untouched snapshot — nothing added, nothing taken SEND COUPON The coupon be- low or a postcard will bring you I tried every type of “apparatus’— FOR FREE my new without results. I¢ was my discovery of THIS illustrated book, Dynamic Tension that did the work! I saw Everlasting at once that the only “apparatus” you need 48-PAGE Heal th and is your own body. I have no use for dangerous FREE Strength.” This contraptions that might strain your heart or other BOOK remarkable book contains actual vital organs. Dynamic Tension is the NATURAL, method of developing you inside and out. In just seven days you'll feel the new muscles starting to bulge! I'll trim your waistline into shape. Your arms, shoulders, legs will quickly be toned into tireless dynamos of POWER. If your neck, biceps or calves are scrawny now—watch them surge up to new, he-man measurements! What's more, Dynamic Tension digs right down after such conditions as constipation, pimples, skin blotches—and gives Nature her first real chance to clear them up, tush them s—with a circulation of clean, purified, healthy 5l Those are strong pror them if I weren't ready to PRO! that—give you PROOF absolute à photographs show- ing you how Dy- namic Tension has developed thou- sands of others— what it can do for YOU! I don't ask you to take my promises. I want you to SEE the PROOF! And I guarantee that you "ll see plenty—in even the FIRST WEEK Where shall I a your FREE copy of “Ever- lasting Health and Strength’??? Tell me at once, so I can get its valuable advice into your hands without delay, Write your name and address carefully on thls coupon and mail it to me NOW. I want to MAKE you the NEW MAN you WANT to be—and T’m ready to do it fast! Address: CHARLES ATLAS, Dept. 62, 115 East 23rd st., New York, N. Y. DARE make Til do exactly Mail FREE ng all mazing DAY TAL OFFER! I CHARLES ATLAS, Dept. 62, 115 East 23rd Street, New York, N. Y. [| I want the proof that your system of Dynamic Tension will make a New Man of me—give me a healthy, husky body and big muscle development. Send me your free book, ‘‘Everlasting Health and Strength.'* Le o Ul lf X nr like the [| [| 3 L| E Names i. oe ee ee eee eee eee ees [| (Please print or write plainly) a a 1 E real living! When Answering Advertiscitexts Please Mention February Modern Mechan'x 33

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Volume XIX Number 4 MIBERUAHIDA FEBRUARY 1938 W. H. FAWCETT, Publisher NEW MARVEL OF SCIENCE LASS is one of the hardest and most brittle substances known to man. Yet comparatively simple but highly ingenious machines trans- form it into a soft, lustrous and flexible ma- terial which is woven into actual “cloth” on ordinary looms, as pictured above. Known as “Fiberglas,” the new textile is not affected by temperatures as high as 700 de- grees, is resistant to corrosive chemicals, does not absorb water, and is a highly effective electrical insulator. It promises to revolution- ize old industries and create new ones as it goes into commercial, large-scale production for the manufacture of such things as cords, threads, ropes, tapes, webbings, filters, awn- ings, curtains, draperies, screens, wall cover- ings, table pads, doilies, pictures, ete. Al~“ though now available only in natural white, the glass cloth eventually will be offered in 35

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Left: These thin mats, composed of thousands of strands of Fiberglas, are used as air filters for warm air furnaces, and indus- trial machines operating in dusty atmospheres. This is one of the many appli- cations of “glass cloth.” Below: Fascinating to watch is this "staple process" of forming glass threads. The molten glass is blown down past the drying flame at the edge of the picture, and forms almost out of thin air as fine white threads, which are taken up on the spools. a wide variety of permanent colors for every decorative purpose. Fiberglas is made by two methods de- veloped by the Owens-Illinois Glass Com- pany at Newark, Ohio. One is known as the “continuous filament" process, the other as the “staple fiber" method. In both processes glass marbles about 34-inch in diameter are fed into electrically-heated furnaces which have a trough or V-shaped bushing made of costly metals of a higher melting point than glass. The molten glass, entering the open end of the bushing, is “drawn” downward by the force of gravity in the continuous-process method, the glass emerging from 102 tiny holes in the bottom of the bushing. These fine filaments, almost too small to be seen with the naked eye unless light strikes them at critical angles, are combined to make one thread-like strand only .024 inch in diameter, for winding on spools. The latter are trans- ferred to machines for fabrication into tapes and cloths. A single marble, weighing only l4-ounce, produces the incredible amount of 90 MILES of glass fiber, so finely are the threads drawn. In the staple-process, the molten marbles are forced downward through tiny holes in similar bushings, but instead of being “drawn,” they are blown downward by blasts of steam under high pressure. Passing through a burst of flame which removes the moisture from them, the fibers gather upon and are drawn from a revolving drum, to be In the “continuous flinent procie 102 fine Tune en CE - 'of glass, formed by tiny holes through whi e wound on revolving spools, which are taken molten glass passes, are formed into a single thread. to textile spinning machines for twisting and They have been greatly retouched in this picture, i actually they are hardly visible to the eye. reduction to thread. ‘ 36 Modern Mechanix

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Foot-Powered Vehicle Travels On Water Or Land ROPELLED by a foot-pedal mechanism, a hydro-cycle invented by M. Villeneuve. of Paris, France, is said to travel with equal facility on land or water. The novel vehicle consists of a boat-like body mounted on axles featuring small rubber tired wheels. A foot-pedal mechanism placed before the driver’s seat is geared to the rear set of wheels, providing locomotion on land. For use on the water, the front and rear wheels of the craft are removed and a set of small paddle wheels is attached to the rear axle. Wind Charger's Vanes Fold Top-——Presenting less air resistance than common windmill types, this novel wind-power generator features collapsible blades actuated by equalizing springs in center housing. Lower photo—The slightest breeze causes the blades to rotate. NEW tail-less wind power generator de- veloped by H. H. Raulerson, of Long Beach, Calif., operates regardless of the posi- tion in which it is set or the direction from which the wind is blowing. The device features four collapsible two-piece vanes connected to a center housing. When the vanes rotate in the wind, one side catches the full power of the wind while the other is folded flat, the action being governed by equalizing springs and small gears located in the center housing. The slightest wind is said to actuate the device. February, 1938 iid Propelled by a foot-pedal gear mechanism, this hydro-cycle travels en water or land. When used on water the four wheels ate removed, being replaced by paddle wheels on reat axle. Croquet Game "Modernized ODERNIZED croquet sets consisting of hard sponge rubber balls and semi-hard rubber mallets are finding favor with game- loving Americans. Produced by a large rubber products manufacturer, the new equipment is claimed to have speeded up the game, requiring skillful play on the part of the participants and creating a new respect and interest which may return the pastime to its former popularity. The rubber equip- ment shows very little wear after unusually hard usage, according to players. Speeding up the game and requiring more skillful playing, tubber balls and mallets have modernized the game of croquet. 37

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OU shoot through a winding tunnel streaked with colored lights, dive under a river, zoom up on the other side, fly past crowded platforms, sway dizzily as you dash around a curve at breakneck speed—it's a crashing, flashing, thrilling scene that thun- ders past as you ride the subway express! Sightseers in New York soon discover the subway to be one of the city's miracles. For five cents they can ride for hours or for days 38 by Donald G. Cooley Left——New "York's mayor, Fiorello La Guardia, in the control cab of the train that opened tbe new link of the Independent Subway connecting Queens and downtown Brooklyn. Top-—-A quick-accelerat- ing, short-stopping train of the Independent Subway pulls into the Hoyt Street station. Subway sta- tions are brightly illuminated and well maintained. on the world’s most ‘exciting underground railroad. When the American Legion held its big 1937 convention in New York, hun- dreds of Legionnaires stated that the big thrill of their outing came when they stood in the first car of a speeding subway train and found adventure around every curve. Cave-dweller that he once was, man finds the subway an irresistible lure. There is mystery in every inch of it, the mystery of Modern Mechanix

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Top—A typical station scene during rush hours. Carrying about 1,000 passengers each, as many as 32 trains enter and leave a station each hour during the rush periods. Right—A subway motor- man at his controls. No current can be applied to the motors until the doors in every car of a train have been safely closed. (I. R. T. photo). Mother Earth who yielded grudgingly to human burrowers. That block which you just flashed past in hurtling seconds—above it rises a $50,000,000 skyscraper. That pres- sure in your ears which warns that you are diving down—over your head flows a mighty river carrying tugs and ocean liners. Actually, New York does not have a sub- way, but subways. There are three systems, the I. R. T. (Interborough Rapid Transit), February, 1938 the B. M. T. (Brooklyn Manhattan), and the Independent, the latter municipally owned. Their routes cover more than 200 miles and on a single day they carry some 4,000,000 passengers. This is equivalent to transport- ing every person in a city larger than Chicago every day. To achieve this major miracle more than 5,000 cars which travel at speeds up to 48 m.p.h. are required. Since Manhattan itself is only 13 miles 39

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24275 T. HUDSON RIVER NEW LOTS ANE ROUTES OF THE INTERBOROUGH RAPID} TRANSIT COMPANY | ee e DVISION | ELEVATED DIVISION | JOINTLY OPERATED Shown above is a map of the New York and sub- urban routes of the Interborough Rapid Transit | Company, one of the city's three subway systems. long, much of the subways’ trackage reaches out to suburban regions. The subway runs under the East River to Brooklyn, under the Harlem to the Bronx, through the Queens- boro tubes to Queens. In the Bronx, Brook- The Subway Comes Up For Air ; r n 4 e e HUDSON RIVER m. Owned and operated by the city, the Independent Subway, the routes of which are shown above, is New York's newest and fastest underground railway, reaching far into Queens. lyn and Queens, it comes out from underground and becomes an elevated. The place to savor the thrill of a subway ride to the utmost is in the very front of the first car of the train. An open doorway with guard-chains hung across it is all that stands between you and the stretch of gleaming track that runs off mysteriously into the dim distance. The motor- man's compartment lies behind a steel door which shuts him off from the rest of the car. The space is just about large enough .to accommodate one man, but since this is a special sightseeing tour we will edge in with him. The train is halted in the sta- tion, the doors are open, and the control handle is moved to its Modern Mechanix BROADWAY. T ew Q CHURCH AY.

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LUSH, ^ SN bro fg cl Ds usd At « B Y Q^ CORONA. Lo h^ mom UNES E " d *- d PARK « INDEPENDENT CITY OWNED . RAPID TRANSIT RAILROAD A ains ‘ Avi. ru 2 Hy A — eon GERE e HE ES EN Ww c e e QweR — wane, N QUEENS D MENS 1691257. BROOKLYN B EXPRESS STOPS ockaway av. KEY OcocAL stops a LINES «+ Ee ————— ae RAPID TRANSIT DIVISION COCEEEITETIGID ELEVATEO LINES SCM SUBWAY LINES © tocat TRANSFER STANON > @ express TRANSFER STATION | & The majority of the Brooklyn-Manhattan Transit subway routes extend into the boroughs of Brooklyn and Queens, as shown on the map above. first notch. The controller is very much Speed! More speed! Speed with safety! like that used on electric street railways. Speed is the driving genie of the subway, The instant the last door closes, the train not alone speed on the straightaway, but starts to move—a precious split-second has speed on the getaway. Ahead of us, around been gained by that little trick of leaving the [Continued on page 132] e 2? control handle “on Two electric bulbs on the controller in front of the motorman light up to give him the “all clear” signal for starting, but they are really unnecessary. While the ear doors are open, no current can pass through the motors; the very second they close (unless the controller is off") voltage hurtles into action and almost by the time the last car has cleared the platform, the train is notched up to full “Time Out" For Periodic Inspections speed to-maintain schedule. ie lisivelsparobody oian subway car is lifted from its February, 1938 “fucks in preparation for thor: ough overhaul. (ER.T. photo).

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SCIENCE BATTLES Almost totally obscured by fog, the disabled schooner Uvira is towed into port by the U. S. Coast Guard cutter Pontchartrain. Note the lengthy towline slung between the two vessels. HE maritime nations of the world are spending millions to obtain speed at sea. The Queen Mary, the Normandie, the Rez, and hundreds of lesser liners plow fearlessly through the oceans at express-train speeds, working on schedules almost as iron-clad as those of railroads. Mountainous green seas, breaking in white foam over the bows, might terrify the landsman, but they are of little concern to the mariner, for they menace neither the safety nor the speed of the ship. It is minute droplets of water, so tiny that . they hang suspended in air, that endanger life at sea—that cost ship owners millions in wages, fuel and lost revenue. Twenty thou- sand collisions in fog during the past ten years have taken toll of 23,000 lives. Fog is still the big menace to navigation—still remains the challenge to science. A few years ago, while on recruiting duty with the Marines, I tried to get a mother’s consent to the enlistment of her minor son. She wired that she consented, providing that he would not be sent more than ten miles to sea. She did not understand that the high seas are comparatively safe—that it is close to shore, especially at the focal points of traffic, 42 Unaffected by magnetic variations, the gyro compass (above) is used in conjunction with ʻa polarus to obtain accurate visual bearings near shore.

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Fog MENACE Left—The 10,000- ton liner Iroquois with her bow high out of the water after grounding on the Maine coast during a heavy fog in July, 1936. The 112 pas- sengers were safely removed, after which the liner was success- fully refloated. à. Mechanical devices minimize the clammy mists .death toll. by Bob Gordon In the photo at left, a lighthouse tender crew is shown placing a tank of acetylene gas fuel in a lamp-equipped channel buoy. ^ Above-—AÀ victim of fog, the Welboro grounded on the rocks off Fisher's Island lighthouse in Long Island Sound. near port or in the harbor, that the real danger lurks. The most vital concern of a navigator is to determine his position when approaching the coast—to keep his ship in deep water and out of the path of other ves- sels navigating in darkness or fog. For this last ticklish stage of an ocean journey, the U. S. Lighthouse Service main- tains 25,000 aids to navigation along our coasts and inland waterways. There are 2,000 such aids in the vicinity of New York alone, 600 of which are within the harbor. These aids consists of lighthouses, lightships, buoys and radiobeacons. 'The U. S. Navy also maintains several radio stations at strategic points along the coast. Upon request these stations will take radio compass bearings and transmit them to the ship. With bearings from two or more such stations plotted on the chart, the ship's posi- tion is readily determined. The ship requires no equipment other than its regular radio to receive such bearings. The radio, however, is not absolute. With only two bearings the lines will meet at a single point. A third bearing will seldom 43

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The bridge of a modern ocean liner (above) is equipped with every known device that will help her officers navigate through fog. Right—Lightship No. 12, guardian of the treacherous Nantucket Shoals. Her sister ship was cut in two when rammed by the liner Olympic during a heavy fog, seven of the eleven-man crew perishing. cross this point, but may form a triangle several miles on each side. The captain will only know his ship is somewhere within this triangle. This failure to obtain an absolute fix by radio is due in part to the fallibility of the human ear, for which no satisfactory substi- tute has yet been found. The man taking these bearings swings a loop antenna over a compass card until the sound of the signal dies out completely. Noting that azimuth, he swings his loop in the other direction until he gets another null. The bearing he re- ceives will be the difference between the two determined fading points. This method is found to be more accurate than attempting to determine the point of the signal’s greatest intensity, but it still permits an error. If this error is only one degree, it will mean an error of four miles to a ship 300 miles at sea. Errors of from five to ten de- grees are not uncommon. Having thus determined his approximate off-shore position while several hundred 44 miles at sea, the navigator making a landfall in a fog will then tune in on the various light- ships and lighthouses having radiobeacon equipment, from which he may obtain con- tinuous bearings, or fix his position by cross bearings in a manner quite similar to that previously described. _ Getting a radiobeacon bearing is just the reverse of obtaining bearings from the Naval stations, in that the radiobeacons broadcast assigned dot and dash signals, which are au- tomatically repeated over and over again. These signals are picked up by the ship’s radio direction finder—a separate receiving set on the bridge, having a loop antenna with an indicator mounted over a magnetic com- pass or gyro-compass repeater. Here again the receiver, this time the navigator, obtains a null on both sides of the signal, and takes NAN as his bearing the azimuth between the two determined fading points. Such bearings are subject to the same errors as those received from shore stations: but, like the dial phone, which allows us to pick our own wrong numbers, the navigator has the consolation of knowing that any errors made are his own. Each radiobeacon sends signals for sixty seconds and remains silent for two minutes, during two ten-minute periods of each hour, except in fog, when it broadcasts continuously. It is the usual practice for ships approach- ing New York from Europe to steer directly on Nantucket Lightship during a fog. In the spring of 1934 the S. S. Washington followed the beacon so closely that it brushed against the lightship, carrying away some of its upper rigging. A short time later the liner Olympic Modern Mechanix

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loomed out of a heavy fog to cut the 133-foot Nantucket squarely in two. Seven men, of a crew of eleven, perished. Since that disaster the Light- house Service has developed a low-power warning transmitter, broadcasting on the same time and frequency as the radiobeacon, that gives out a distinctive warble note. When this note is heard, the navi- gator knows it is no longer safe to steer directly on the beacon. The Lighthouse Service has completed installation of equip- ment on most of its lightships that synchronizes the compressed air fog horn with the radiobeacon signal by means of an electric timer. The radiobeacon has a si- lent period of a few seconds near the end of every third minute. There is then a one-second warn- ing note on both the radiobeacon and the fog horn, a one-second [Continued on page 118] February, 1938 Radio direction finders (left) help mariners deter- mine a ship’s position when sky and sea are ob- scuted by fog. Top—By taking soundings with a fathometer, as shown in top sketch, a navigator can check depth of water under his ship’s keel to avoid reefs. Shown above is a chart of ocean depths from Nantucket Lightship to Halifax, as recorded by a fathometer aboard $, S. Cyrus Field.

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Builds Odd Sternwheel Using a washing machine motor, two fan pulleys from a refrig- erator, spokes from an old chair and other salvaged materials, Louis Goodman of Detroit, Mich., built this sternwheel boat. OWERED by a one-cylinder gasoline en- gine salvaged from a washing machine, a novel sternwheel boat constructed by Louis Goodman, of Detroit, Mich., carries three persons at a speed of five miles per hour. The craft is steered by moving the sternwheel and motor unit by means of a handle that projects from beneath the motor frame. The sternwheel can also be raised or lowered, per- mitting use of the boat in shallow water. ` Goodman constructed the sternwheel, which has a diameter of three feet, from odd pieces of equipment such as two fan wheel pulleys from an old refrigerator, spokes from an old porch deck chair, and six flat pieces of board. A curved and adjustable galvanized sheeting shield serves to protect occupants of the boat from the spray caused by the churning of the sternwheel. Chemical Ends Dye Bleeding OU might shudder at the odor of a stale egg, or turn up your nose at the smell of a bad fish, or choke on ammonia fumes, but the ammonia which chokes, the hydrogen sulfide gas which makes the egg smell bad, and the phosphine gas which makes the fish smell foul, are the basis of the newest test tube “babies” for the textile industry—the “onium” compounds. Watch particularly the quaternary am- monium, phosphonium, and sulphonium chemical infants. These are complex com- pounds with hearts of nitrogen, phosphorus and sulphur atoms. They bring joy to the textile dyer, printer and finisher, who is re- 46 sponsible for the beautiful color and finish of the clothes you wear. Does the dye in a dress “bleed;” that is, run when it is wet or con- tacts perspiration? Just dip it in a warm solution of cetyl pyridi- nium bromide, rinse and dry. Notice how fast the dyes become. Water and perspiration no more make them run. Did the dyer put the wrong dye on the fabrie, or didn't the dye go on evenly? He needn't worry. He can strip the dye completely from the fabric and dye all over again. Trimethyl ‘cetyl ammo- nium bromide, another one of those new “onium” compounds does the trick. Other of the “onium” chemicals whose names need not worry the layman have now made it possible for the dyer to use wool dyes on cotton and synthetic silks. This is helpful for the wool dyes have always been of brighter shades than the others. Boat Device Exposes Drunkards one CMM Professor R. N. Harger shows a Missouri trooper his new de- vice for checking amount of alcohol in autoist's. breath. "DRUNKOMETER'" device, designed to determine the amount of alcohol present in the breath of persons arrested for driving while under the influence of liquor, was re- cently demonstrated at a National Safety Congress held in Kansas City, Mo. . The test Modern Mechanix

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apparatus was invented by Pro- fessor R. N. Harger, chemistry professor at the Indiana Univer- sity School of Medicine. To operate the “Drunkometer,” the suspect blows his breath into a rubber balloon to which is fitted a tube leading into the machine proper. The balloon is then emptied, the air passing through ` tubes containing special chemicals which register the amount of alco- hol fumes present by changing in color and clearness. New Tire Irons Aid Mired Cars ONSISTING of two pairs of steel bars fastened at each end with U-shaped irons, a device in- vented by Louis Karon, of Su- perior, Wis., is said to provide an improved means of enabling an auto to pull itself clear of a muddy ditch or snow bank. The new device can be attached to an auto wheel in a few minutes time without lifting the car from the ground. If necessary, it can be installed directly over regular type anti-skid chains. Additional extensions to the bars give even greater traction in soft snow. The U-shaped steel bars of a new auto tire device (bottom) are said to enable a car to free itself from a mud ditch or snow bank. Device is installed without jacking car (top), February, 1938 Family Of Three Travels In Home-Built "Cyclemobile" The A. Martin family of Dracutt, Mass., uses this ‘'Cycle- mobile" for trips to nearby towns. Vehicle consists of two bicycles joined together and covered with a canvas hood. WO bicycles joined together by means of a specially constructed frame and covered by a streamlined, water-proofed canvas hood, serve as a novel and cheap medium of trans- portation for A. Martin, of Dracutt, Mass. Dry batteries supply current to operate the front and rear lights of the “eyclemobile,” as the odd vehicle has been named. Resembling an automobile of radical design in its appearance, the cyclemobile's hood boasts ising-glass windows. The interior is fitted with luggage compartments and a berth for Martin's 18-month-old daughter. Hus- band and wife work dual sets of pedals. Machine Jots Code On Tape ESIGNED for attachment to any radio receiver, the code reader device illustrated here transforms code signals into a visual record of. dots and dashes on a special chemically treated tape. The machine will op- erate at speeds up to 300 words per minute. 47

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NTENN or KDK 500 WATT BEACON TOWER BROKEN AT 336-FOOT LEVEL FOR SECTIONALIZING INSULATORS 360 COPPER WIRE RADIALS PLACED UNDERGROUND EACH RADIAL 700 FEET LONG SPACED ONE DEGREE APART STARTING AT BASE OF TOWER | FORMING A COMPLETE CIRCLE AS SHOWN BY DOTTED LINES. RADIALS CONSTRUCTED OF NO. 8 COPPER WIRE MAKING A TOTAL LENGTH | OF APPROXIMATELY 48 MILES EIGHT-WIRE TRANSMISSION LINE FROM STATION WwESTINGHOUSE PORCELAIN INSULATOR U CONCENTRIC CABLE TRANSMISSIO LINE TO SUPPRESSOR ANTENNA —TYPICAL EXAMPLE TRIANGULAR STEEL TOWER Sla FEET | BETWEEN LEGS—718 FEET HIGH WITH LADDER ON INSIDE KDKA's new 718-foot antenna is composed of 32 three- cornered welded steel sections placed one atop another (above). The 60-ton structure rests in a ball-and-socket joint of a huge porcelain insulator, as shown at left. OWERING 718 feet high, a new vertical an- tenna erected for radio station KDKA in East Pittsburgh, Pa., will enable primary broadcasting service to be given over an area ten times greater than that previously provided. The mammoth an- tenna, claimed to be the highest welded structure in the world, is encircled by eight 90-foot antennas designed to suppress interfering waves normally emitted in radio transmitting. To improve the conductivity of the ground around the antenna, 48 miles of copper wire have been buried a foot under the surface, radiating out, one degree apart, for 700 feet. A brilliant aviation beacon tops the skyscraper antenna. SIX STEEL GUY WIRES BROKEN AT INTERVALS BY INSULATORS EIGHT WOODEN POLES 90 FEET A SUPPRESSOR ANTENNA OF COPPER TUBING AS SHOWN BY TYPICAL EXAMPLE — POLES LOCATED 504 FEET FROM BASE OF TOWER Plan layout of the complete antenna system. The efficient ground system reduces effect of skywave emissions. | HIGH FORMING A CIRCLE AROUND TOWER— EACH POLE SUPPORTING

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Street Alarm Box Calls Either Police Or Firemen N EMERGENCY alarm system developed by Berkley E. Cover, of Chicago, Ill., enables a call to be made for policemen or firemen, according to the emer- gency, from the same signal box. The sender of the alarm can talk into a microphone at the street signal box or, if too excited to talk, can send the alarm by turning dials marked “Fire” and “Police.” The street signal boxes in the new alarm system are connected A new street alarm box (left) enables fire or police alarms to be sent verbally over a phone or by turning proper dial. Central switchboard operator (above) receives call and sounds alarm in fire or police station that is nearest the street box from which the original call was sent. to the switchboard of a central office. Upon receiving an alarm, the dispatcher at the central office speaks into a microphone connected to loudspeakers in every fire station in the city. In less than one minute, the fire-fighting apparatus nearest the blaze is on its way. The same procedure is followed in contacting police stations in order to send a patrolman, squad car, or emergency crew wherever needed, enabling authori- ties to gain control of situation in minimum time. TTACHED to the barrel of a service re- volver, a compact motion picture camera enables a policeman to take action pictures of any person at whom the revolver is aimed. The pictures thus obtained can be presented as evidence at court. The motion picture camera is triangular in shape and is attached under the barrel of the revolver by means of metal clamps. The lens is directly in line with, and under, the revolver muzzle. The camera is set in action by a slight pressure on the revolver trigger, independent of the firing of the weapon. Due to the compact size of the gun camera device, only a small roll of film can be accommodated at one loading. If you are interested in items described in this issue, send a stamped, return envelope n MESES E I , Attached to the barrel of a revolver, a new compact motion for a tist of manufacturers addresses. picture camera helps policemen secure evidence of crime. 49

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Night view of the E. I. du Pont de Nemours & Company plant at Deep- water, N. J., which can produce one million pounds of neoprene yearly.

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HE diversified chemical manufacturing industry of America is finding a way to make this country free from dependence on foreign sources for an increasing number of vital raw materials. Only a few years ago, Ameriea depended on the nitrate beds of Chile for fertilizers and raw materials for industry. Today, it makes its own ni- trates from the air. . Camphor was from time immemorial a natural monopoly of the Far East. Today, America makes its own synthetic camphor for medicine and the needs of industry. A large and inereasing number of medicinal *Plasticizing: and’ drying neoprene. Apparatus unlike -anything the chemical industry ever before knew made it possible for chemists to produce a rubber substitute. that excells Nature's product in its adaptability. Neoprene resembles natural rubber more closely than any other artificial product. An X-ray discloses that its physical structure is the same even though its © chemical composition is different. Photo shows one | 1 of numerous steps required: in processing neoprene. and other compounds, formerly imported, are now being produced here. And now rubber may be added to this list of essential raw materials. Rubber is a vital element in our life. It is used not only for tires but for thousands of other products that are essential to our industrial civilization. More than ninety- nine per cent of the world's rubber is grown in the tropies. Many attempts have been made to grow substitutes for rubber in the United States, but none has ever succeeded. Millions of American dollars, British pounds, and German marks have been ex- pended during the past fifty years in an attempt to produce a synthetic rubber; that is, a product identical with natural rubber made by chemical means, preferably from raw materials that are freely available in . these industrial countries. All of these efforts to produce a true synthetic rubber have met with failure. Germany, during the World War, did produce a synthetic product that was used as a substitute for rubber, but it was a very poor imitation of the natural product and consequently its production was dropped as soon as the war ended in 1918.

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Finished articles made of neoprene (right) not only look like those made of crude rubber and have the same elasticity and tough- ness, but also have the added ability to resist the action of oils, gasolines and solvents which destroy real rubber. Because of these advantages neo- prene's use increases daily. Some of the massive equip- ment used to carry out the chain of chemical miracles involved in the production of neoprene is shown be- low. The process consists of an intermarriage of cet- tain gases to produce liquid chloroprene, which in turn is converted into the tough, rubber-like solid known as neoprene. In 1925, research chemists of the du Pont Company began to work on the rubber prob- lem, but they did not try to duplicate natural rubber as others had done. “Why,” they said, “should we assume that the product created by nature for an entirely different purpose is the best material for making the thousands of rubber products that modern industry re- quires? Why be content to reproduce in the laboratory the product that Nature has pro- vided? Let’s start with different raw mate- rials and produce a product that is even better adapted to present-day industrial re- quirements.” Among other things, they visualized a process for the production of a 52 rubber-like material from acetylene gas. The first experiments were quite disappointing, but help came from an unexpected quarter. The chemical director of the du Pont Com- pany attended the first symposium on organic chemistry which was held in Rochester by the American Chemical Society. At that meeting, Father J. A. Nieuwland of the Uni- versity of Notre Dame told of the results of some of his experiments on the chemistry of acetylene. Father Nieuwland had been studying the gas and conducting research into its properties for many years and was recog- nized as the outstanding authority on its be- havior from a scientific point of view. His report told how he had succeeded in causing acetylene to polymerize, or, in plain words, to form giant molecules by combina- tion of smaller molecules with one another. Acetylene when combined in this way became _a different chemical entirely called di-vinyl- acetylene. That was something that the du Pont chemists had not tried. Arrangements were made to have Father Nieuwland’s ex- periments duplicated in the du Pont labora- tories and an effort was made to convert this di-vinyl-acetylene to synthetic rubber, but it did not work. From di-vinyl-acetylene the . chemists were able to obtain only the hard, brittle resins that Father Nieuwland had already produced. The next step in the pursuit of a better rubber substitute was taken by a group of chemists who found that by changing the [Continued on page 118] Modern Mechanix

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Belt Drive Replaces Wheels On Novel Motorcycle DA acenot o pHOTOGRAPHY section | «Sete AL EVELOPED primarily for operation over rough ground, a new type of motorcycle invented ` - = by ae Lehaitre, of Paris, France, Equipped with a drive belt instead of wheels, this '"'tractor-cycle" is said i to traverse steep hills and rough roads with ease. A military adaptation of features a tractor-type drive belt the novel cycle is shown on the MM cover miniature reproduced at the left. as its means of locomotion in place of conventional wheels. Named the “tractor- trol a sideways motion of the drive belt. cycle" by the inventor, the novel vehicle is The tractor-cycle could easily be adapted said to be superior to an ordinary mo- for military use, as depicted on the cover of torcycle in its ability to climb steep and this issue by a Mopern MEeEcHanix artist. rough grades, although its speed on level Fitted with a machine gun, the cycle could be ground is limited to about 25 m.p.h. Steering used by dispatch riders or entire military is accomplished by handlebars which con- units to travel over shell-torn terrain. Power-Driven Timber Saw Has =a) Blade POWER-DRIVEN saw used to cut timber during the construction of a huge wood crib at Grand Coulee Dam in Oregon features a blade that actually stands still while the cutting process takes place. The “secret” of the novel saw is that the teeth run on an endless chain around the blade, which merely serves as a guide for the teeth as they cut into the timber. A three-horsepower compressed air motor drives the chain. The saw is so de- signed that it can also be used under water without impairing its efficiency. Addresses of manufacturers of products mentioned in MODERN MECHANIX can be : r These workers are using a novel saw featuring a blade that obtained by sending a stamped, self-ad- stands still! The cutting teeth run around the blade on an dressed envelope to the editors endless ¢hain, which is powered by a compressed ait motor. February, 1938 53

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Scale Model Demonstrates Novel Racing Vessel m uui NNNM ox are A scale model enables Otto von Kories to explain how hollow steel drums will propel a new vessel in which he hopes to travel over the water at a speed of more than 180 m.p.h. SCALE model of a streamlined vessel in which he hopes to attain a speed of 180 m.p.h. has been constructed by Otto von ' Kories, of Los Angeles, Calif. The model fea- tures all the equipment that will be found on the full-sized vessel when it is built, according to the inventor. As shown by the model, Kories’ design re- lates to a non-sinkable craft which will have a draft of only six inches, traveling over the water on hollow steel drums that act as paddle wheels. Driving motors will be located upon stationary carriages within each drum, being connected by gears to the circumferences of the drums. Three-foot circular openings in the ends of the drums will permit entry to the interior in the event that motor trouble de- velops. Control will be maintained from a bridge at the forward end of the novel craft. Foot Pedal Controls Mainsheet Of Ice Yacht TEERED by a wheel instead of a tiller, an ice boat produced by a leading manufac- turer features a special clamping device that enables the skipper to hold the mainsheet by means of foot pressure on a pedal. The device automatically releases the sheet as soon as the foot is lifted off the pedal. The bottom of the new ice boat is rounded, the runner plank being set flush with the bot- tom so as to reduce wind resistance. The craft is 18 feet long and features a 13-foot runner plank for single-seater types and an 11-foot runner plank for two-seaters. A hollow mast of clear airplane spruce, which is secured in such a way that it will rotate freely and set itself automatically at any angle to the boat which continues the curvature of the sail, is also featured. Designed for Class E racing, this ice boat features many improvements. 54 Close-up shows pivot joint of free-rotation mast. Modern Mechanix

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Navy Acquires Giant Patrol-Bomber Flying Boai Four engines of 1,050 horsepower each are required to power this huge Sikorsky flying boat. LAIMED to equal any known plane in military load-carrying capacity, a new patrol-bombing flying boat has been con- structed for the U. S. Navy by the Sikorsky . Aircraft Company, of Bridgeport, Conn. The huge aircraft is powered by four Wasp en- gines. of 1,050 horsepower each and is equipped with the latest type three-bladed constant speed propellers. Designated as XPBS-1, the bomber is an all-metal, high-wing, full cantilever mono- plane of new design. Every known approved device for safety and ease of operation is in- corporated in the construction of the craft. While strictly a flying boat, provisions are made for the carrying of beaching gear, such as is shown in the above photo, to facilitate beaching, docking or ramping when desired. The new flying boat features an innovation in equipment—a 110-volt electrical system which generates power for all electrical units such as flaps, anchor winch, radio, lighting system, bomb controls, etc. An auxiliary ‘ gasoline engine drives the generator supply- ing the electricity. Complete radio equip- ‘ment, comparable to that used on a destroyer, is installed in the Sikorsky bomber. The armament of the XPBS-1 consists of bow, rear, and center gun turrets incorporat- ing many new features in design. Being soundproof throughout and equipped with commodious living accommodations for the. crew—a mechanics workshop, galley with electric stove, water distiller and diy-~ice re- frigerator—sustained military operations are possible without affecting the physical en- February, 1938 Plane has three gun turrets. durance of the crew. No performance data has been released as yet. Machine Analyzes Coloring RECORDING photoelectric spectro- photometer, an instrument which auto- matically determines the light reflection properties of any object by means of a com- plex photoelectric system, has been developed by a leading ink manufacturing firm. Ap- plicable to all types of color analysis work, the machine can also be used in determining chemical compositions. In operation, the color sample to be tested on ihe machine is placed at the end of a long tube. Its characteristics, transmitted by a photoelectric system, are then translated into a prosaic curve traced on a recording drum. This photoelectric device enables operator to analyze color. 55

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Za FLYING SORT RESSES ARE NOT NEW! — ALTHOUGH THE U.S. ARMYS NEW FLYING FORTRESSES WITH 8 MACHINE GUNS ARE CON- SIDERED THE LAST WORD IN DEFENSIVE AIRCRAFT, INIS2I THE ARMY HAD A PLANE MOUNTING THIRTY MACHINE GUNS AND WAS PROTECTED BY 8 INCH i ARMORED STEEL = Card Jacoby, Brooklyu, MY [J ARTH SUPPLYS FISHERMEN WITH PAINT/—NEAR LUBEC ME. MATERIAL FOUND IN THE GROUND,WHEN MIXED WITH FISH OIL,FURNISHES PAINT WHICH HAS BEEN USED BY FISHERMENFOR NEARLY A CENTURY, TOPAINT i H g THEIR BO. UTOMOBILES PRODUCE WATER! Cerald redd] Aubuz ffe, i \ FOR EVERY GALLON OF GASOLINE ; BURNED, APPROXIMATELY ONE GALLON OF WATER IS PRODUCED IN TUE FORMOF VAPOR EXHAUST.— Fred A. Janke, OzÁ mong Pe. wu = A PENNY PLACED TIGHTLY à- = GAINSTEACHDRIVE WHEEL OF A LOCOMOTIVE WILL PREVENT TT FROM STARTING — -ohn PlessnecHeHeury LU. Five dollars will be paid for the oddity selected by Nic Sprank as the best of the month. One dollar will be paid for all others used on this page. Send your oddity to Nic Sprank, Editorial Office, Modern Mechanix, 1501 Broadway, New York, Y. Source or proof of each oddity must be given. Send all oddities separately, not with other manuscripts or letters. 6 uou

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Photo Lens Registers Rays Predating Dinosaurs ELIEVED by its makers to be the fastest in the world, a new astronomical photo- graphic lens has been used at Mount Wilson Observatory in Pasadena, Calif., for taking pictures of light rays which, scientists claim, left distant stars before dinosaurs trod the earth. In conjunction with the 100-inch re- flector at Mt. Wilson, the new lens has photo- graphed spectra of nebulae 30,000 times fainter than the faintest star visible to the unaided eye. Dr. M. L. Humason, who conducted the Mt. Wilson Observatory tests, reported that the speed of the observatory's spectrograph was doubled through use of the new lens, which has a speed of F. 0.59. Astronomical data placed the nebulae observed by Dr. Humason as being an estimated distance of 80 million light years from the earth. Through use of the new lens, scientists can now ob- serve faint objects which have previously been deemed hopeless from an astronomical viewpoint, according to Dr. Humason. Compound Irradiates Heat Gatvanometer tests of steam-heated cubes, one painted with a new compound developed by W. F. Alder and the other un- painted, indicated that treated cube gave 40 degrees more heat. PPLIED to a surface like paint, a new compound developed by W. F. Alder, an Altadena, Calif., scientist, is said to possess great heat absorption and irradiation quali- ties. In tests, galvanometer readings indi- cated that a steam-heated cube of polished copper painted with the compound had a temperature 40 degrees higher than a similar untreated cube. "The compound is being used by California fruit growers to increase the heat given off by smudge pots placed in orchards during periods of frost. This new photographic lens enabled astronomers at Mt. Wilson Observatory to take pictures of nebulae estimated to be 80 million light years away from the earth. Dr. M. L. Humason adjusts lens, believed to be the fastest in the world. Kiddies Taught Traffic Laws MINIATURE roadway complete with signs, stop-and-go lights, crossings and safety zones is being used to teach pedestrian and auto traffic regulations to school children in Brentwood, England. The lessons are made interesting for the tots by letting them ` drive miniature autos over the "highway," impersonate policemen, etc. ` English tots learn traffic rules by means of this “highway.” 57

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Top photo-—Relief map of Vicksburg (Miss.) Center-—Making a model use in an historical exhibit. mold from a clay relief map. National Military Park. Indian village for Lower--Pulling ihe ea) e by Walter E. Burton r MHE man in the lookout station leans for- -L ward tensely. His eyes ache as he gazes through his binoculars. Yes, there is a wisp of smoke all right; and it seems to be grow- ing in size. Looks like the fire might be near North Fork. The lookout leaps across the floor to a re- lief map hanging on the wall. With his pencil he traces a route the nearest fire-fighting crew can take to reach North Fork. Two or three times he has to back up and detour around small, but deep, canyons or small streams whosé sides are steep, and which might delay the crew too long. It is but a matter of seconds until he has worked out the shortest and easiest route; and not many more seconds until the men from the nearest Station are preparing to depart. In a few hours, thanks to quick work of the forest fire fighters, thousands of dollars worth of timber, scores of wild animals and perhaps even a number of human lives have been saved from the Fire Demon. But the story might have been different, if that relief Not child's play, but a

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map had not been at hand for pointing out the quickest route to the fire. Behind that map is a story of Uncle Sam as an up-to-date builder of models and man- hood. For the map in question is one of the products of government model laboratories operated by Civilian Conservation Corps boys as part of the Emergency Conservation Work program. There are two such laboratories in the country. One of them is at Fort Hunt, A sculptor (top) checks a clay model to be used in making a diorama. The hunter (above) was modeled for use in a miniature group depicting commercial Buffalo hunting during pioneer days. A CCC worker (left) com- pletes the running gear of a. wagon to be used in a model display. Considerable re- search is undertaken to as- sure authenticity of details in fully completed models. Virginia, not far from George Washingtón’s historic home at Mount Vernon. The other is at Berkeley, California. These laboratories carry out projects of model building and relief map making sanctioned by a committee. The models serve a variety of useful pur- poses. Perhaps the superintendent of a na- tional park will want a relief map of the park to exhibit to visitors to acquaint them with the topography of the region, or a diorama valuable service is this branch of government activity.

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A general view of a workshop in Uncle Sam's Model Laboratory at Fort Hunt, Va., is shown above. Experienced model makers are in charge, Model trees (above) are made of permanent ma- terials. Contours on a relief map are developed from heavy cardboard layers, as shown below. to explain some historic event, or natural or scientific feature. The original relief map of a certain area may be duplicated many times for museums or schools which are willing to pay for the materials required to make the casts. In laying out trail systems and roads through parks or other territory, thousands of dollars may be saved by making prelimi- nary layouts on relief maps instead of making expensive surveys on the actual ground. When working out a fire control system for the protection of a forest area, a relief map is of great value in selecting the most ad- vantageous positions for observation towers, eutting trails, and placing fire-figbting equip- ment. In reforestation work, a relief map makes it easy to work out a planting schedule, so that trees will be placed where they will _thrive best and do the most good. The use of a relief map for helping fire fighters reach a forest fire by the most convenient route already has been described. But relief maps are not the only projects turned out at the government model labora- tories. Carefully-made scale models of his- toric Indian villages help tell effectively the early history of the country. Sometimes the relief map of a region includes a complete model village or town, each detail, down to. the smallest building, being faithfully repro- duced to scale. For instance, a model of the Hot Springs, Arkansas region, includes scores [Continued on page 128]

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Eve Exerciser Apparatus Resembles Circus Wheel ESIGNED to strengthen eye muscles through exercisé, a new apparatus in- vented by Dr. William I. Henry, of Akron, Ohio, resembles a carnival chance wheel in appearance. The device consists principally of a large rotating disc to which toy animals are attached in slots in such a manner that they assume different positions as the disc rotates by mechanical means. To use the apparatus a patient sits before the disc, placing the chin on a special rest. Watching the antics of the toy animals as the dise rotates at various speeds provides exer- cise for the eye muscles. Edison Memorial Bulb Ready Standing 14 feet high with a diameter of 9 feet, 6 inches. this electric bulb will be placed atop Edison Memorial Tower in Menlo Park, N. J. Interior features 960 electric lights GIANT electric light bulb, 14 feet high. which will surmount the $100,000 Edison Memorial Tower at Menlo Park, N. J., in commemoration of the invention of the incan- descent lamp by the famous inventor, has been completed. The bulb, in position atop ihe 150-foot tower, will also serve as an air- ways beacon. The bulb consists of 164 pieces of glass cast in two-inch diamond patterns around a steel skeleton frame. The interior features 960 in- candescent lights and a 24-inch reflector. Placing her chin on a rest pad and watching antics of toy animals as they pass by on a rotating disc, this young lady indulges in an exercise said to strengthen eye muscles. Three In Family Blow Glass STREET shop in Los Angeles, Calif, displays glass-blown decorative objects created by three generations of artisans— father, daughter and grandson. The grand- son, Dick Manley, is only ten years old, but already has four years of glass blowing ex- perience to his credit. Together, they have created an interesting exhibit of the glass- blowers’ art which includes objects such as sailing ships, airplanes, animals, candle holders, flowers, trees etc. Three generations—father, daughter and grandson—of gíass- blowing artisans display their craftsmanship in this photo. 61

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"Planeometer" Detects Minute Pavement Deviation Deviations in highway pavement as small as 1/100th of an inch are readily detected and magnified by this "Planeometer" device, which is used by Oregon State Highway Commission. Builds Midget Locomotive MINIATURE locomotive designed and built by Robert Hunter, of Wilmot, South Dakota, is said to be capable of hauling a train of cars carrying ten persons weighing approximately 1,800 pounds without reducing its power or speed. Mr. Hunter is 50 years of age and construeted the locomotive and cars in his home workshop during spare time throughout winter months. The miniature locomotive is complete in every respect. Weighing 1,140 pounds, the engine is five feet long and is rated at six and seven-eighths horsepower. Two hundred and forty feet of oval track are used as a “right-of-way” for the complete train. Transporting his home-built train to fairs and other celebrations, Hunter has developed an extensive business by taking interested spectators for a ride over the oval trackage at ten cents per passenger. Controlled from its tender, this home-built locomotive has. a power rating of 675-horsepower. It successfully hauls a train load of ten passengers weighing about 1800 pounds. -62 NABLING authorities to check the work of laborers as well as traffic load effects, a “Planeometer” device used by the Oregon State Highway Commis- sion detects deviations as small as .01-inch in any ten feet of pave- ment parallel to the center line. The machine was invented by W. C. Newell, of Portland, Oregon. The amount of variation is re- corded on a special scale, being magnified four to ten times. A chalk marking device attached to the machine marks the rough spots as they are encountered, enabling work crews to re- locate the points of deviation later when repairs are to be made. Device Bares Vocal Chords Angela O'Byrne, voice authority, examines the vocal chords of Thomas Freebairn-Smith, radio singer, with an "'auto- phonoscope" consisting of tiny mirrors in a long tube. ONSISTING of an intricate maze of hid- den mirrors in a long, slender metal tube, one end of which is inserted into the mouth far back toward the throat, an “auto- phonoscope” device enables voice teachers to peer at pupils’ vocal chords while they are in action. Tiny, but powerful, electric bulbs at the tip of the tube provide light within the pupils throat during the examination. Modern Mechanix

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Private Planes And Boats Engage In Sham Battle NOVEL sham battle between private airplanes serving as bombers and small cabin cruisers serving as an enemy fleet was re- cently staged on Long Island Sound. Sacks of flour were used as bombs by the aircraft, while cameras constituted the anti-air- craft defense of the pleasure boats. Swooping low over the zig-zag- ging motorboats, the airplane pilots dropped their flour bombs, hoping to score a hit on the decks before their planes were "shot" down by the cameras in the hands of the eager boat crews. Booth Is Minus Door TELEPHONE booth without a door, yet without a disturbing sound, is on exhibi- tion at the Museum of Science and Industry in Chicago, Ill. The doorless booth is made quiet by liberal use of sound absorbent ma- terial and is kept cool by perforations in its sides. The sound absorbent material creates a "zone of quiet" inside the booth. : Miniature Autos Exhibited These young ladies are comparing the craftsmanship of two models entered in a miniature auto show staged in New York. MINIATURE autombile exhibition staged at the International Building in Radio City, New York, for the benefit of the Boys’ Brotherhood Republic of New | York City, featured many excellent models ranging in size from tiny vehicles one foot long to several capable of seating two persons. February, 1938 —á Swooping down upon pleasure boats representing an "enemy" fleet, privately owned airplanes dropped bombs, in the form of sacks of flour, during a sham battle on Long Island Sound. Chain Stump-Puller Devised POWERFUL, noiseless and hand-op- erated chain stump-pulling device which uses the principle of the hydraulic jack, has been developed by the German engineer von Nickish-Rosenegk. A steel tripod is set up over the stump to be pulled and chains at- tached to the stump. These chains fasten into one end of a plunger which gradually ascends, due to the pumping on the handle of the hy- draulie jack. A force of over 66,000 pounds thus created pulls out the stumps. Exhaust Gas Made Harmless ESEMBLING a muffler in appearance, a device designed for attachment to auto- mobile exhaust pipes is said to burn up carbon : monoxide gas before it can escape into the air, thus reducing the danger of concentrated exhaust fumes in garages, tunnels, etc. The burner l contains a special porous earth, to which copper oxide has been applied. The hot exhaust gases mix with air drawn in through a vent in the burner and glow brilliantly as they pass over the copper oxide, which causes dissolution of the poisonous mon- oxide gas before it is released. 63

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Elevator Garage Stores Auto Under Lawn Of Home Restricted by law from building a regular garage on his lawn, a London suburbanite solved the problem by installing an elec- trically driven elevator garage under the lawn. Controlled by switch (center photo), the elevator quickly rises or descends. ACKING room to build a garage at the side of his home and being forbidden by city ordinance to erect one in front or at the rear, a suburban Londoner solved his prob- lem by installing an elevator garage under Aircraft Has Bird-Like Wings NSPIRED by the actions of birds in flight, R. Passatt, of Surbiton, England, has con- structed a flying machine that features wings shaped like those of the feathered fliers. “The Lark,” as the novel aircraft is called, is equipped with a ten-horsepower engine and a propeller which provide forward motion, the bird-like wings revolving rapidly to create vertical flight only. The wings of “The Lark” are not only Presenting a novel appearance, this flying machine features bird.like wings covered with gauzy material to “catch” air, 64 the front garden. The elevator is electrically driven and control switches within the house cause it to rise or lower within a few seconds. -When in a fully lowered position, the elevator roof is flush with the ground. shaped like those of a bird, but are covered with a gauzy material which is said to catch the air like feathers do. The entire aircraft weighs only 360 pounds, the motor and wing mechanism being mounted on a metal frame encased in a wooden fuselage. Hobby Results In PWA Job OBBIES sometimes grow into million- dollar projects, as the experience of H. A. Siedelmeyer, a U. S. Forestry Service draftsman, indicates. Some years ago, Siedelmeyer became in- terested in building relief maps as a hobby. It wasn’t long before the Forestry Service decided that he was just the man to super- vise P. W. A. construction of a great relief map of national forests of the west, which will be placed on exhibition at the 1939 Golden Gate International Exposition to be located on à man-made island in San Fran- cisco Bay. The relief map, which is now two-thirds completed, will be approximately 100 by 150 feet in size and will cost about one million dollars. The map is being built on a scale of one inch to the mile and at the peak of work about 800 persons wil be employed. Modern Mechanix

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Railroad Tests Mile-Long Stretch Of Welded Track NE of the longest stretches of continuous railroad track—a mile-long pair of welded rails—has been placed in heavy-duty service near River Valley, Pa. With 75,000- pound engines hauling from eight to ten trains a day, each having up to 125 loaded cars, the welded track is being used as a proving ground where American railroads can learn the ability of the novel trackage to stand up under heavy traffic. The cost of maintaining the new type of track will be made available to all railroads. Welding the sections of track into a con- tinuous unit was accomplished by the ther-: mite process, wherein the rail ends are brought tightly together, placing a mold around the joint, preheating rail ends and generating liquid steel by thermite reaction, letting the molten steel run into mold. Fire Box Traps Pranksters Demonstrated above is a new fire signal box that locks the hand of alarm sender until released by a policeman or fire- man with a key, thus deterring the sending of false alarms. HE sending of false fire alarms by mis- chievous persons may be eliminated through use of a newly developed call box. To use the device, the sender of an alarm must passva hand through a special compartment to reach the signal dial. Once the dial has been turned, the sender’s hand is locked in the compartment until released by a fireman or policeman with a key. February, 1938 Flexible enough to bend around a 15-degree curve without being fastened to the flat cars, a mile-long continuous stretch of welded track is carried to a Pennsylvania test site. "Legcuff' Prevents Running RIMINALS are prevented from making a break for freedom while being trans- ferred from court to jail through use of a mechanical "legcuff" recently devised. The device permits the prisoner to walk or sit, but locks and holds the leg in a flexed position should he attempt to run. Simple in construction, the "legeuff" is held to the leg by means of small chains which pass through locks attached to steel bars which are pivoted by a ratchet mechanism at the knee. Criminals can walk, but not run, when wearing the "'legcuff" demonstrated. above. Device locks if running is attempted. 65

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COLOR FILMS- A "HOBBY" INVENTION N INTEREST in photography as a hobby is responsible for the development, by two talented musicians, of one of the greatest advances iu the photographic field since the appearance of the first camera—pictures in color. Leopold Godowsky, Jr., a pianist, and Leopold Mannes, a violinist, are the young men who have achieved world renown through development of the Kodachrome process, which may revolutionize some phases of the photographic art. The. world today honors them for their con- tribution to the science of colored photog- raphy because, strange as it may seem, neither man happened to like football while attend- ing a school in Riverdale, N. Y. While other students reported for football practice, Godowsky and Mannes spent their time walk- ing over the countryside. During their numerous walks they developed an in- terest in photography and considered the possibility of photographing, in color, the picturesque woodland scenes they saw dur- ing their jaunts. The crude experiments of their school days led them, 18 years later, to the elaborate Eastman Kodak Laboratories in Rochester, N. Y., where further experiments finally cul- minated in the production of Kodachrome color film, now available to the owners of movie and “still” cameras. The invitation to use the facilities of the Kodak laboratories was exiended to the two hobbyists in 1931 by Dr. C. E. Kenneth Mees, vice-president of the film and camera company, who had supplied materials, apparatus and advice to the experimenters as far back as 1926 during their early research work. Godowsky and Mannes developed their hobby into an industrial venture of the first magnitude only by hard and never-ending work. During the 18 years before their invention was crowned with success, experi- ment followed experiment as their enthu- siasm surmounted each tantalizing discouragement. Every spare minute be- tween concerts and recitals was given over to study, reading and experimentation. Finally, in 1931, the pull of their hobby became para- 66 Forsaking the musical field, in which they attained no small degree of success, Leopold Gowdowsky, a pianist (left), and Leopold Mannes, a violinist, "rode" their photography hobby to world renown as the inventors of Kodachrome film. Photo shows the youthful inventors at work in Eastman Laboratories. mount and they laid aside violin and piano for the chemist's test tube. Today, the “hobby riders" continue their work as Eastman Kodak Laboratory tech- nicians. Each pays tribute to the efforts of © the other and to the assistance provided by fellow workers in the Rochester laboratories. The fruit of their work stands as a monument of inspiration to all other inventors and hobbyists whose work, at first, may not be blessed with success. Modern Mechanix

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Speed Up Of Coast-To- Coast Air Travel Shown HE tremendous advance made in speed- ing up commercially operated coast-to- coast air transportation is strikingly por- trayed in the photograph at the right, released by United Air Lines. Through development of high speed aircraft, the time required for a transcontinental flight has been reduced from 33 hours to 15 hours, while the ticket cost to passengers has dropped from $400 to $149.50. The first transcontinental transport planes carried only two passengers in a small, poorly ventilated cabin. Today, club-type “Main- liners” carry 21 passengers in quiet, com- fortable salons. Super “sleeper” planes transport 12 passengers in berths larger than a twin bed and provide individual dressing rooms for men and women passengers, while real linens, silverware, etc., give a regal air to meals served aloft. Artist Makes Wood Pictures J. W. Show, a California artist, exhibits one of his unusual pictures made up of bits of untinted wood secured from forests throughout the world. Pictures are 34-inch thick. SING bits of wood containing natural colors, J. W. Show, a California artist, has developed a new method of expressing his art. The wood is used to make pictures, each piece being fashioned and placed in po- sition to complete a desired scene. Wood from twenty trees is usually required to com- plete a picture and months of tedious work are involved in the process. February, 1938 Ten Years of Coast to Coast Flight 11937-15 hours à) Progress in transport plane design, with consequent lowering of time required for transcontinental flights, is shown in above photo. Top to bottom—~Boeing 40; Boeing 80; Boeing 247; Douglas DC-3. Larger planes are under construction. Build "Mock Up" Air Liners OOD, in the form of Douglas Fir ply- wood, still plays an important part in aircraft production, the principal use of the material being in the construction of “mock | ups’—full size models of projected new planes. The “mock ups" provide engineers with a visual reproduction of their plans, enable pilots to test control locations, and help determine seat arrangement, finish, etc. E» Before building an airplane, engineers first construct a wooden "mock up’? model to determine seating arrangement, etc. 67

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t Arc welded together at the factory, this all-steel house is delivered to purchaser by means of a 12-wheel trailer. Fittings, plumbing and wiring are installed while en route. NEW development in home construction is an all-steel home which is are welded together at the factory and delivered to the purchaser in a completely finished condition. The new type homes are of average size and feature three bedrooms, four other rooms and a lengthy central hall. Plumbing, fixtures, and wiring are installed in the steel homes while they are enroute to the purchaser. Special flat trailers equipped with 12 wheels and pulled by powerful trucks are used to transport the ready-built dwell- ings to the purchasers’ lots. Machine Air-Conditions Tent LACED against the side wall of large tents such as are used by circuses, a newly developed machine blows fresh air, chilled by passing over ice, into the tent by means of a canvas duct suspended over the heads of the audience. Only 200 pounds of ice is consumed by the unit during an average day's operation, it is claimed. The air conditioning machine is carried on No longer need circus patrons complain of the heat within the "big top", for this new machine completely air-conditions tent interior by blowing fresh air through an ice-filled duct. lded Home Developed a two-wheel trailer and power for its motors is supplied from the show's . lighting plant. When not used for the comfort of patrons, the equipment can be utilized to provide cool quarters for performers, working crews and animals. Airplane Uses Lamp Oil NABLE to secure proper fuel for his Diesel powered airplane when he landed at Kabul, Afghanistan, a Ger- man pilot tried lamp oil in the engine. The motor worked satisfactorily on the unusual fuel, enabling the plane to make its next flight of 1,000 miles without trouble. "Stiltmobile" Aids Mailmen The large wheels on this "Stiltmobile" are said to enable it to travel over roads of heavy mud without becoming mired. ESIGNED for use by rural mail carriers who must travel over roads which are frequently covered with heavy mud and snow, a new “Stiltmobile” is equipped with greatly enlarged wheels, elevated fenders and a specially designed body. The odd looking machine is said to travel 20 to 30 miles on a gallon of gasoline. For ordinary transportation purposes, the large wheels and elevated fenders can be removed and replaced with conventional types. Sea Level Drops Yearly HE Caspian Sea is three feet lower than it was one hundred years ago, according to a scientists recent report. The sea has been dropping steadily at an irregular rate, the report states, because the 300 rivers and lakes flowing into the sea do not compensate for losses of water through evaporation. Addresses of manufacturers mentioned in Mopern MEcHaANIx can be obtained by send- ing a stamped, self-addressed envelope to the editor.

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Machine Cuts Ánd Blows Hay Into Truck Or MACHINE developed by a tractor firm in Milwaukee, Wis., chops up hay and blows it into a barn mow, eliminating the tedious job of removing | the hay from a wagon or truck with pitchforks. When placed in a silo, the chopped hay is said to preserve as well as "long" or unchopped hay. In operation the entire hay machine is hauled to a field by a tractor where a silo-filling unit picks up the hay and deposits it in a funnel-like cutting ma- chine. The cutting machine chops the hay and drops it into a blower device which blows the chopped hay through a pipe leading to a waiting truck. The same blower is then used to blow the hay into barn mows at a later period. The advantages of stowing away the hay in chopped form lies in the fact that three tons of it can be stored in the same space that one ton of uncut hay would occupy. Bus Rider Wears Gas Mask To eliminate headaches caused by monoxide gas, B. P. David- son wears a gas mask while commuting to work on buses. EADING a campaign to impress local bus operators with the need for some means of eliminating the monoxide fumes that pro- duce headaches and cause passengers to suffer attacks of nausea, B. Palmer Davidson, of Montclair, N. J., wears a gas mask when commuting to his office. The mask is a type used by employees in industrial plants. Fr Cutting hay into small bits, enabling a large quantity to be stored in a small space, this machine ālso loads hay into trucks or barn mows by blowing it through a long pipe. Nail Holds Fractured Bones A “hip nail guide," one of the latest ap- pliances used in treatment of bone frac- tures, was recently demonstrated before members of the American College of Sur- geons attending a convention in Chicago, Ill. Constructed of Vitalium, one of the strongest known metals, the device guides a special type of nail accurately and rapidly into a fracture | when tapped with a metal mallet. The nail serves to hold the fractured bones in proper relationship to each other during the healing process. A. M. Stephenson, inventor of the new surgical device, conducted the impres- sive demonstration, aided by a nurse. Tapped with a metal mallet, this device is used to guide a special nail into bone fractures. Nail holds bones in proper relationship to each other throughout the healing process.

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Montgomery Mulford LARGE number of postage stamps pic- ture railroad subjects, including loco- motives and railroad bridges; it is said that there are about 130 types of loco- motives shown on issues from all about the world. - The modern stream- lined train has yet to appear on United States or British issues, but other countries have pictured this mod- ern mode of transpor- tation. The 1936, 40- ore Swedish stamp pic- tures a streamlined steam locomotive simi- lar to the famous "Royal Scot" at right. Several of these postage issues picturing locomotives were issued primarily to com- memorate the first railways; others appeared to mark the international railroad congress meetings. Thus Egypt, in 1933, issued a set of commemoratives showing old and new locomotives—four different styles were de- picted on the stamps. In 1935 Belgium celebrated its first loco- motive, issuing stamps picturing the first as well as the latest used in that country. The first one, of 1835, was named “La Belge," and it was pictured on the lower values of the [Continued on page 142] 1 "These are but a few. of the many stamps issued by the various countcies throughout the world to commemorate raii transportation. Left to right are shown the railroad stamps of San Marino, Spain, South Africa, Nicaragua and France. 70

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= ~~ Sat and HOBB en Pattern for making bird appears at left. Photos 1 and 2 show spring and - cord mechanism. Right— The completed project and perspective assembly. 2 MR (for ST 7. 2^ Foe c A /, CIGARETTE E US CUT > CONSTRUCT ls DRAWER OPENS ; =~ HOPPER TO ; ; | ALLOW DRAWER AN! EASY SLIDING FIT .TRAY FOR CIC ARETTES 6D. NAILS 3" iB DIAM. WOODEN ROLLER S" > ' t B OU probably never saw a real E z f BOTTOM live bird that looked like this ffo d 4 b ecu one, but then you never saw a real 9. 9 PRINCIPAL. PAI live bird do what this one does. NN Ges utis SEMBRA When you want a cigarette he bobs i d .72 SECTION THRU DRAWER down and comes up with one in his S 9 4 beak, just like that. Unlike most À ha | [Continued on page 140] | HOLE O, " 2 | WOODWORKING . RADIO . METALCRAFT . BIOLOGY - CHEMISTRY SPORTSMENS CAMPFIRE . HOME AND SHOP PROJECTS . HANDIEINKS : 1

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SIEPS IN MAKING an Inlaid Footstool Completed, the inlaid stool makes a useful living room decoration. OR your next lathe project, why not make this lovely inlay foot stool? .It has an unusual design and the striking contrast between the white pine and s figured gum top makes fit addition to any room. The first step calls for placing the stock, for the top, on the lathe face plate and turning it down to size, The small, center screw type . was used throughout this job. Next, the recess in the top side for the white pine dise is cut out, care being taken to have the cut square. The piece is then removed and a block of white pine l-inch thick cut down to make a tight for the hole. The cross design is laid out on the pine and this jig sawed out with | a slight taper—the bottom being very slightly smaller than the top opening. This taper insures a tight glue joint for the inserts when they are tapped home. Proceed by putting the block for the top back on the face plate, wiping glue inside the recess and around the rim of the pine block, then tap home with a block of wood under the hammer. Before doing this a pattern is taken of the insert size. Four pieces are sawed to shape, slightly oversize. These are fitted one at a time, their 72 by Dale R. Van Horn size reduced by holding them lightly against the sanding disc. Glue holds them firmly in place. All four inserts, however, should be fitted and a trial assembly made first to insure a good fit. While the inlay design shown is simple and of plain lines, any suita- ble figure can be used, such as the outline of a scottie, swan or some other appropriate . design. Scribe a circle to designate the posi- tions of the top leg dowels on the under side, divide into 6 spaces and, with a cloth pro- tecting the top, bore the dowel holes 34-inch Left — Tap white pine inlay disc in place with a block of wood and a hammer. The glue should be pre- viously applied to the disc so as to. hold it in securely. Below — Fit each piece, inserted in the cross, in the white pine disc in- dividually. After a good fit has been obtained, apply glue to the edges and hammer them ‘down into position.

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Jig-saw the white pine disc to a slight taper so the figured gum inserts can be tapped down to provide a tight fit. " 6 HOLES wo SPACED \ | LU* EVENLY i oY E 93" NE E ‘ek x DETAIL OF INLAY $ BASE SEGMENTS-AREQD — ^ ^ Oee Ye deep. Put the piece back in the lathe and finish with a good coat of clear lacquer. Later rub it lightly with No. 000 steel wool and finally wax. The base is a simple turning. To get away from such a large piece setting flat on the floor and perhaps teetering a little if the floor is not true, a depression is turned l4-inch deep in the bottom side of the base. Most of the remaining wide, shallow rim is then sanded away to leave 4 or 6 feet as indicated. These will not be conspicuous, nor need they be included if not desired. They will be desirable, however, under most conditions. [Continued on . page 120] Apply glue to each dowel before fitting the top and bottom to the legs. Glue is also applied to inside of i ee holes. WHITE PINE FIGURED GUM DISC I" DEEP E a INLAY PIECES w 27 oe. | ah e 2" STOCK = f ; E f FIGURED “SECTION THRU BASE SHOWING SANDED FEET e) Left — At this stage the top is ready for polishing. The deco- rative inlay around 2" STOCK the edge of the top POURED is a narrow pine strip glued into a “VY” : Du LEGS 7/8" groove made with a à SQUARE — shaped file tang. Fin- i : CORNERS ish the top by apply- = ROUNDED ing a coat of clear = SLIGHTLY lacquer. When dry, i ES E rub with No. 000 * SANDED > 7 3/8" HOLES steel wool and last FEET EE ER E 3/4" DEEP polish with wax. A : c MO wm Él : COMPONENT PARTS & ASSEMBLY 73

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THESE WINTER PROJECTS ARE EASY TO MAKE s5: LEFI) £i jn can Jer de handle _ o_o SA eue! braces plank sol af xc ; ot ajou. a ee raka This snowball target thrower permits the trapshooter to con- tinue practice throughout the winter. Construction is of odd planks as shown. A piece of inner tube operates catapult. V "a hand SP 4, sang < nut f EO LOIN v ga" brace

Here is an ice scooter that is simple enough for any young- “ster to construct. Odd lumber, cut to the dimensions s can be utilized in order to keep cost at minimum. To insure rigid construction, all members should be fastened with screws. 1 beveled runner Bamboo poles exa or 70140" cotton sail large screw ey Although extremely simple in construction, this ice surf board will provide endless thrills. Using a single runner, it travels over ice with little resistance. On windy days a simple sailing rig can be added. An old sheet will serve admirably as a sail. 74 oer] esc M wn. Lia hood 10 wide y Aida Car No elaborate work is involved in building the toboggan car described above. Planks 1 by 10 inches form the bottom. The. hood is formed from tin. Sides are cut from 1 by 10 inch stock. 122" pm" ong UTII ty ro^ use hoards from Old bicycle handle bars are used for the steering mechanism of this speedy ice coaster. Cut all parts to dimensions shown, making them from hardwood if available, otherwise use pack- ing case material. Plane and sand runners perfectly smooth. E s uii L746" J rd z C room stiot Sharpened CL Dufaf, “Lee Se The Dutch’? IceSled described in the above detail needs little explanation. Scrap lumber is used throughout in its construc- tion. The occupant seats himself in the sled and uses the broomstick pushers to provide the necessary motive power.

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HE modern grille illustrated in the accompanying details not only serves as a disguise for the unsightly living room radia- tor, but makes an attractive fernery as well. The grille is of plywood con- struction throughout. No dimen- sions are given, since they will depend entirely upon the radia- tor over which the grille is to be installed. Three-quarter inch plywood is recommended, al- though if necessity warrants, lighter stock may be used. False shutters or louvers made from plywood strips 2 inches wide give the grille a distinctive appearance. Fern boxes of the “balcony” type are secured in grooves at each end. The com- pleted grille should be painted in colors that will match the decorative scheme of the room in which it is to be used. ip a HOLES FOR LOUVER TENONS This practical and decorative plywood cover also serves as a home fernery. PLYWOOD CONSTRUC- CONSTRUCTION OF CORNERS, | VA" X 172! GROOVES - ed FOR FERN BOX

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HE reason that amateur glass blowing is such an in- teresting hobby is that the work "Gathering" glass is an impor- @CtS as a stimulant to your tant operation. Notice the creative ability. With very small glass tubes and corks A z ^ used for holding larger tube Simple and inexpensive tools, blown, flame. Left sua" in a corner of a room or in the type, nine jet gas-air burner. attic or basement, you can -© quickly learn to make dozens of useful and ornamental pieces such as vases, small glasses of different shapes, beverage sippers and other articles of that nature. With further practice and experience you will not find it difficult to make the tiny animal, bird and flower novelties or “what- nots," which are so popular in the home, and know that the design is original and that a Similar article cannot be purchased in the stores. Í E If you are an amateur chemist, a knowledge of glass blowing will enable you to repair broken retorts and other apparatus, in Modern Mechanix This home-made glass blowpipe de- livers a hot flame. Inner tube is for air, outside tube for gas.

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by Kenneth Murray addition to making test tubes and other small equipment. Or do you prefer to dabble with electricity? Then try blowing glass bulbs for homemade experimental electric lamps, along the line of the mercury-are type of light, which is similar to the well-known “neon” tubes. Amateur model makers frequently have use for miniature glass parts, and in fáct there are very few crafts or hobbies where a knowl- edge of glass blowing would, not be useful. Locate the glass-blowing laboratory in a convenient corner free of drafts and with poor illumination, so that it will be easier to judge the condition of the heated glass. An ordi- nary workbench, about 3 feet high, is satis- factory, or use a kitchen table. Cover the top with sheet asbestos, or preferably asbestos board, and at the back provide a rack for holding your stock of glass tubing in various sizes. .February, 1938 The attractive bud vase at extreme left was made by blowing a series of bulbs and pushing them flat. The bird nov- elty was shaped from a solid glass rod. Close-up photo at right shows forma- tion of a beverage sipper from tubing. All amateur glass blewing, and a con- siderable amount of professional work,. is done with glass tubing instead of using molten glass in a heated retort. You will find that soft sodium glass is most satisfactory; it should have walls at least 1 mm thick, and a bore of from 5 to 10 mm for general work. Quite often you can purchase this at a local drug store or high school laboratory, other- wise you can order it of a scientific supply house. Ordinarily the tubing is offered in 5 or 6-foot lengths and costs as little as 25c a pound, according to the amount purchased. Professional and advanced work is done with two or more special blowpipes which oppose each other and are fed with both gas and air under pressure. A professional outfit of this kind is shown in one of the illustra- tions. However, the beginner can handle small work with the aid of a bunsen burner 77

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ful flame. Attach rubber tubes with stop-cocks to control the amount of gas and air. The latter can be supplied by a small foot bellows. Adjust the mixture to give a hot blue flame that ends in a fine point. : Rotation: In order to heat the tubing evenly it is necessary to keep it revolving in the flame, gen- erally by turning it with the left hand. In case the middle of the tube is being heated; use both hands. This must be done carefully and in synchronization so that the glass does not become twisted. _ Ordinarily the professional glass blower heats each end of the tube and draws it off into a narrower tub- ing, which is broken off to leave a smaller 6-inch spindle at each end. The spindle is much easier to turn than the larger tubing. A more satisfactory method for the beginner is to secure a number of corks in different sizes and drill them to take short pieces of small tubing. These can be inserted in either end of the working tube and serve as remova- ble spindles. Glass is not a good conductor of heat, so the corks will not become charred. “Gathering” Glass: This is a most important operation for the beginner to learn. Possibly you have tried your hand at : glass blowing in the past and have given it up because on blowing the heated tubing it quickly expanded into a [Continued on page 128] After blowing a series of bulbs in the tubing that will form the bud vase. proceed by heating the end and flaring. Use a putty knife ground into a tri- angular shape for this operation. Use the corner of the tool to form the flutes, as shown. Beverage sippers made in the home workshop find appro- Ptiate use as prizes for bridge parties or social gatherings. After heating the end of the bud vase, gradually force the flaring tool into the tubing with a twist- ing motion. This work must be done over the bunsen flame as depicted at right. such as those used for chemical experiments. The larger size, like the one shown in use by the author, will afford a much hotter flame and is to be preferred. It is also supplied with extra gas jets of different sizes, which allow some degree of control over the gas-and-air mixture. If the mixture is too rich there is the possibility that the glass will become darkened as it is heated. If you should wish to construct a profes- sional-type blowpipe at once, you will find that one made entirely of glass gives a very power- 78 : Modern Mechanix

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pine Piltings eg o Torch Stove For Home Use OE SUPER HEATING * BLOWTORCH STOVE EXCEPTIONALLY HOT FLAME ot "u 2-4 REDUCER ^ HOLES DRILLED NEAR TOP NIPPLE., FILLED WITH T"«CONCRETE TO DEFLECT FLAME UPWARD BLOW torch is a great convenience in the home workshop, and at times is a very necessary piece of equipment. The two- inch nipple connected to the floor plate should be of sufficient length to make the opening into which the flame is pointed the correct height. The torch will throw an exceptionally hot flame upward. Tobacco Can Makes Swab 1: >? of using an expensive paint brush for paint remover, an empty tobacco tin with the help of small pieces of cloth or bur- lap wil do the job just as well and far more in- expensively. Any loose heavy cloth will do to fill the ean. After it is in position, the end of the can is hammered to hold the cloth tightly in place. Spike Tightens Barrel Hoop RAILROAD spikeisa handy tool for lightening loose hoops on bar- rels. The spike in its regular form is shaped so that no fur- ther work on it is required. In use, the head is placed on ORDINARY RAILROAD SPIKE IDEAL TOOL FOR meu ENING HOOP ON KEGS, BARRELS AND TURS.. February, 1938 the edge of the hoop to be tightened, and struck forcibly by a hammer. Blade Holder Gives Even Cut HE safety blade holder showninthe drawing will be found to be a most useful de- vice for the home workshop, inas- much as it can be adjusted to s make any depth of cut from the TEC of a piece of paper to.one-quarter of an inch. Any convenient piece of strap iron, steel or brass may be used. i | | i pen RAZOR BLADE FITS BETWEEN SIDES ere Clips Aid Aid Soldering ee RDINARY í P O — PINCH í ge» paper clips of the spring va- Er ex | riety, when pre- pared as sbown in the drawing, make it possible to solder wires close to insula- tion without burning. Several thicknesses of asbestos should be used to line the clips. Roofing Holds Pipe In Place STRIP OF CORRUGATED ROOFING CUT SOMEWHAT WIDER THAN DISTANCE THRU WALL FITTED INTO HOLE IN WALL MAKES "GOOD THIMBLE FOR STOVE PIPE . BEND TO GO AROUND STOVE PIPE HERE stove pipe runs through a parti- tion, ceiling or floor, it is advisable to have an air-cooled thimble around it to eliminate possible fire danger. A strip of corrugated roofing, cut slightly wider than the depth of the hole in which it is to be used, will end danger and present a good appearance. 79

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PRACTICAL HOME SUGGESTIONS Special Putty Repairs Leaded Glass HE constant opening and closing of doors fitted with leaded glass windows, often results in the glass cracking during cold weather. Such breaks can be repaired so as not to be noticed ware waite) by simulating the lead with putty. DARKENED WITH Make the putty from either commercial white lead and a good grade of whiting or from pure linseed oil and whiting to which has been added enough lampblack to give the mixture the dull gray color of lead. Apply the putty to both inside and outside of the window so glass will be held secure.—G. H. T. m Vacuum Cleaner Aids Furnace Draft DISC PiVOTED DISCARDED N EFFICIENT blower for home furnaces that do not draft properly can be quickly assembled from the motor and fan mechanism of an old electric cleaner. Remove the unnecessary parts from the motor and mount to the side of the furnace with a strap iron bracket. A hole cut in the side of the furnace allows for insertion | of blower end of cleaner. Draft is regulated by a metal ux] disc attached over the vacuum fan. A 7-watt bulb in series with motor prevents it from running too fast. FLY SCREEN KEEPS DIRT E FROM FAN switch | i, Rugs Made From Cast-Off Clothing — Pim | ANY housewives are finding a new use for cast-off clothes (orien, VA ed by converting them into attractive throw rugs. The old clothing is cut up into strips about 1 inch wide, then wound on a length of stiff wire bent into a U-shape. The base of the rug is cut from burlap and the strips sewed fast on a sewing machine. As each strip is secured, the wire is pulled out and the operation continued until rug is completed.—Mrs. E. R. HEAVY WIRE B M Y || Hose Silences "Singing" Guy Wires SILENCED ^ \ UY wires such as used to support chimney stacks often produce an annoying buzzing or singing sound on windy days. To overcome this simply cut several pieces of garden hose about 1 foot long, slotted at one end to allow for the insertion of the guy wire. The opposite ends of hose sections are tacked to the roof. Stitches Add Life To Window Shades FTER being in use for several months, the cheaper grades of roller type window shades usually show wear at the edges. Any housewife having access to a sewing machine can {ef p 3... avoid expense for new shades by sewing parallel stitches along BREF? aco ure sont GS both edges of fabric with thread matching color of shade. ^ emm 80 Modern Mechanix

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BUILD THIS STURDY 12" Band Saw . by Melvin A. Noecker and Douglas P. Rolfe HIS saw is built to standard size, handles any wood up to 6 inches, and cuts to center of a 24-inch circle. It has adjustable blade guides above and below the table and the table itself may be ad- justed to any angle. The operator is protected by a 2-inch guard which covers all but the exposed working portion of the blade. The saw illustrated cost the designer only ninety-five cents to build! This, the sole expense, was incurred for the 4% by 78-inch blade, the remainder of the parts being taken from old cars and obsolete farming machinery. As some of these parts may not be available to prospective builders, the drawings show substitutes in certain cases. Anyone with an in- genious turn of mind can probably equal or even better these with the material available in his own locality. p “SLOT FOR i2" BLADE J fso u WALNUT l8 x 2" ^' 8/8" X 2" DOWELS j "a STAGGERED 2" CARRIAGE , BOLT ~a \/2" X 3/4" HARDWOOD BRACKETS - CLAMP OVER PISTON PIN PIVOT - SPACE TO AT suit CONNECTING ROD HEAD COUNTER SUNK HEAD y, 22 LAG S SCREW DETAIL Á STEEL PIN AT "A" ROLLER PISTON PIN WING NUT ~ LOOSEN TO ADJUST February, 1938 SEE F1G. 5 FOR BLADE TENSION en SHD 7 LA MS PE si SEE FIGI FOR [A DETAILS OF f TABLE & IT'S PA | SUSPENSION A e [gos FORD T CONNECTING ROD TABLE COLUMN SEE FIGS.5 AND || 2 FOR DETAILS OF SAW FRAME AND BEARINGS | | 8" DIAM. X 5" | | FACE PULLEY . FROM GRAIN a SEPARATOR : ~OR TO SUIT —- MELT / us ANCHORHOLT CREAM | SEPARATOR BASE OR B MAKE OF ANGLE IRON fS AS SHOWN IN FIG.3 t FIG.4 FOR DETAIL This illustration shows the band saw as it looks when com- pleted. Details of the parts indicated are described on the ensuing pages. Left—Perspective plan of saw table. Start with the base. In studying the draw- ings and photographs you will observe that two types of base frames are illustrated. The Anchor Holt cream separator base used in the original is fine if you can get hold of one handily, but the angle iron type shown in Figures 2 and 3 will prove equally satisfactory and is, moreover, quite easy to construct. 81

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B NSVERSE | CONNECTING OD BLOCKS | ROD POST LENGTH OF OLD REAR AXLE l-74" DIAM.- HUB ` ENO UTILIZED ANGLE IRON BASE -SEE FIG.3 BELOW | BEA RER SEE DETAIL OF MOTOR MOUNT FIG.2 REAR ELEVATION OF SAW SHOWING ALTERNATIVE BASE FRAMING If this base is anchored solidly to the floor the legs E may be given considerably less spread, making it still easier to build. The frame is either bolted or welded to- gether. Note that the top rails are mitered at the ends. The saw frame on the origi- nal was taken from an old gang plow. However, it is simply formed from ordinary 34 by 2-inch bar iron to the dimensions given in Fig. 5. When obtaining the bar iron enough should be purchased to cover the other frame com- ponents as shown in Fig. 5. Slots are cut in the saw frame to permit ad- justments of table column and guide arm units, also, although not shown, for the upper shaft anchorage. Exactly 634 inches from the U end of the saw frame, are drilled and tapped for the Y!2-inch and 5s-inch bolts 82 Ua"x 2" BAR IRON BEARER(2 READ FlG.3 BASE n ) DETAIL. 4 which hold the tension adjustment pipe in place. The %-inch tap occurs at the top of the frame as shown. The exact purpose of this pipe and the manner of fitting it will be explained later. In the meantime, tap as mentioned and the frame is ready to set up on the base. The frame and a 9-inch length of 34 by 2-inch bar iron rest parallel, directly on the base as indicated. Across them are placed two timbers which carry the main drive bear- ings. As the exact size of these timbers de- pends upon the style of bearing obtained, the dimension will have to be fitted to the job. It must result in the 19-inch dimension given between centers of the band wheels and, as the bearing blocks referred to are bolted clear through the bar iron members into the top rails of the base, it will be necessary to de- cide upon the main shaft bearings before bolting the saw frame down. A length of old rear axle sawed off, re- taining the hub end, makes a good main drive shaft. Two main bearings from an old car — TIGHTEN TO INCREASE TENSICN OFBELT DRILL FOR BEARING / LOCK BOLTS SPRING. CHANNEL meas MOTOR MOUNT DETAIL " 5 14 ANGLE IRON 3" CHANNEL IRON The plan drawing at upper left shows the basic dimensions. The 19-inch dimension be- tween shaft centers is important and must be provided for. Lower de- tail shows motor mount and angle iron base. SLOTS eS p y 5/i6" STOVE BOLTS(ORJO/ATS MAY BE WELDED) e) engine will serve for the bearings of this shaft. (Ford T bearings were used on the saw depicted here.) The bearings are bolted, as shown, to the hardwood timbers or bearing blocks; the exact width and height of these blocks depends, as already stated, Modern Mechanix

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upon the type of bearing used. > The band wheels are 12-inch : brake drums complete with hubs, in this instance from an old Elgin car. They are faced with rubber taken from an old, large inner tube (see Fig. 8) and mounted with the flange side facing the frame. The lower drum is fitted directly to the axle shaft that forms the main drive shaft of the saw. This presents no difficulties at all, but the mounting of the upper drum is slightly more complicated. The upper wheel is supported by a 1-inch shaft which is threaded on one end. The shaft passes through the ball bearing (which in this wheel is re- tained) and is clamped to the inner race by means of a nut and washer on either side, the’ The simplicity of the band saw is verified by these pictures show- GUIDE ARM FiG.6 ing both f d sid iew DRILL AND TAP * " n g O! ront arn: side views. FOR 5/6" DIA, 7 SERIA SAR IRON UPPER GUIDE ASSEMBLY GUIDE ROD 5/8" X 14" / 20" E N vd UM GUARD ADJUSTMENT ! | SUPPORT SLOTS palin STRIP OF || HEAVY q INNER TUSE TURN DOWN FOR l/2" DIA. SHOULDER GUIDE ROD V2" PIPE SLEEVE FLANGE un TENSION ADJUST- MENT LOCK NUT 3 BRAKE DRUM SING WITH HUB NX 2x78" BLADE FIG.8 DETAIL OF DH BAND WHEELS ADJUSTMT. SLOT 172" PIPE FOR TABLE TE COLUMN TWIN STEEL RIVET 2 BRAKE ROLLERS BANDS TOGETHER 2" WIDE m WASHER BOLT THRU HARDWOOD BLOCKS à TO TOP OF BASE FRAME 3/4" BAR IRON ADJUSTMENT 2" SCREW FIG.5 DETAIL OF SAW FRAME _ a {4 STRAP IRON RIVET OR BOLT STEEL PIN ball bearing being held in place a by the outer hub. The drum | B A ROLLER - FIG.9 DETAIL OF now revolves freely on the Y S eu AR ORT shaft, which in turn is anchored to the frame either in the Frome iene nce and arsi aga d details of n. ; Pand pul fitina: . are shown in this group o letails. e manner in whic the lower guide [Continued on page 124] roller and piston pin projects from the saw pivot is shown in Fig. 7 insert. February, 1938 83

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Tubing Gives Spring To Hook RUBBER TUBING SCREEN DOOR CREEN doors can be kept closed more tightly if held with these spring-acting hooks. The screw eye and the eye on the hook are spread open to permit a short piece of rubber tubing to be slipped over them. In use, the two rubber covered eyes give a spring-like action to the hook. Bracket Strengthens Door SUITABLE repair for shaky and sag- ging doors ean be made by fastening ordinary brackets to the inside corner of the door as shown in the drawing. The bracket should be slightly nar- rower than the thickness of the door frame so that there will be no projection to spoil the ap- pearance of the door or to catch on clothes as persons pass through. This same arrangement may be used to good advantage on other wood frames. Felt Cleans Clothes Line DOUBLE clothes line that has wire guides circling the line to keep it on the pulley can be kept clean 84 if equipped with this simple felt cleaner. It consists of a round piece of felt slit to the center with a small groove around it to hold the cleaner in place. Screw Eye Ends Hasp Danger WINGING lock hasps constitute a con- Stant danger to clothes, and at times have caused serious injury to persons running into. them. This dan- ger can be elimi- nated by a screw eye placed so that it will fasten the hasp out of “the way when it is not needed. The screw eye should be placed so that the hasp can be folded back out of the way with the eye passing through the hasp opening. By twisting the eye slightly, the hasp will be locked securely out of the way. Tubing Protects Door Finish ANY times the spring on a screen door is placed so that it rubs and scrapes the finish on the door when it is opened and closed. This can : be stopped by 7 = stretching a short length of rubber . tubing over the: spring, thus offering complete protection for the finish. This tub- ing also will prevent small children from getting their fingers caught between the coils. Hooks Form Box Handles OXES can be lifted and moved easily : about the home or shop if equipped with common coat hooks as shown in the drawing. The first three fingers fit the shape of the handle, making the box easy to carry. For boxes holding heavy material, larger hooks should be used. Modern Mechanix

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Pull Loop Saves Cord Wear ANY poor connections in a separable plug can be traced to the fact that the plug has been removed from its socket by someone using the cord as a handle. If a piece of linen cord or string is used instead, the problem of poor connections will' be removed. To attach this cord to the plug, make two small holes in the fiber cover which fits over the prong connectors. Then thread the cord through these holes and out through the hole in the rear of the plug used by the wire. A Port-Hole Door Knocker HIS door knocker has a useful as well as decorative purpose on any house, because it not only notifies the householder that some- one is at the door, but permits the person knocking to be seen before the door is opened. The circular brass rim is cut from medium gauge brass, seven inches in diameter. The handle is a strip of brass, one-half inch wide and five and three-quarters inches in diam- eter, with the center flattened at the top. The .ends are bent so as to produce a graceful appearance. Cut out a base from plywood, one-quarter inch thick, and seven inches in diameter. Turn down the back to form a depression equal to the thickness of the pane of glass to be mounted in the base. This glass should be about six inches in diameter, while February, 1938 . when a pipe must the opening in the door should measure about five inches. Drill holes in the brass rim three- eighths-inch from the outer edge so that the screws will clear the glass. Solder a small brass hinge to the handle and to the port- hole rim for mounting the knocker. Sander Aids Sticking Door OORS which do not open and close readily because they rub on the floor usually must be taken off their hinges before a sufficient amount of stock can be removed to eliminate the difficulty. How- ever, with this device, the nec- essary amount can be taken off without remov- ing the door. The flat piece of wood for carrying the sandpaper should be thin enough to be inserted between the door and the floor at its widest point. Although almost any type handle can be fitted to the device, the handle from an old plane will be found most suitable. To pre- vent marring the painted or varnished sur- face of the door as the tool is moved back and forth, a thin strip of wood is clamped along the edge. Pipe Tee Forms Floor Flange LD pipe tees can be converted easily into efficient floor flanges for attaching a pipe to a floor or wall when regular flanges are not available. It is necessary only to saw the fitting as shown in the drawing. Dril holes at each end of the tee for the mounting screws. Flanges made in this manner are especially useful be mounted at an angle to the floor or wall. By careful planning, the tees can be cut so that when set in place the threaded hole will extend in the required direction. 85

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Into a narrow bottle place a few crystals of copper sulphate or “bluestone.” Cover these with a few inches of water. Then add several pinches of soap chips and shake the mixture for an instant. It will be found that a beautiful emerald-green solidified mass develops. This is caused by the soap solution reacting with the copper sulphate, which has an acid reaction. “SHADES OF IRELAND by Prof. Victor Lewitus Make a strong soap solution by mixing shaving soap and water. After taking a puff on a cigarette, blow the smoke through a bubble pipe to make a soap bubble. The inside of the bubble then will contain the white smoke, and when it breaks, it does so with a puff, furnishing a very striking. experiment. A clay or corncob pipe will be more suitable than the CUIDIFIED briar variety, inasmuch as the soap mixture probably GREEN MASS — Q- will make the pipe unsuited for further smoking. FIGHTING FIRE WITH SOAP é Below—Fill three drinking glasses of the same ARING s z size half full of water. Use ordinary tap water NS 7 in the first; the same water for the second into which has been placed some salt; and distilled. or rain water for the third. Place small equal quantities of soap into each glass of water and shake each for the same length of time. Notice that a thick lather will form quickly in the dis- tilled or rain water while practically no suds will appear in the salt water. The tap water probably will have suds but not as many as in the rain water. This experiment will show the softness of tap water as compared to the other extremes. . Into a glass of water place two tea- spoonsful of. bicarbonate of soda (baking soda). After it has dis- solved, add one or two teaspoonsful of soap chips, which should be dis- solved before proceeding with the experiment, Finally add some ordi- nary vinegar and notice the thick, voluminous foam that forms. This type of mixture may be used to ex- tinguish ‘a fire, and is very successful because of its tenacious character. If a sufficient quantity is avail- able it will act as a blanket covering the burning area. 86 HOW HARD IS YOUR WATER?

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7 3 02. LIME WATER Below—Into a small glass receptacle place two ounces of water. Then pour into the water a half an ounce of mineral oil. Shake the combi- nation and note that within a short time after the shaking, the oil and water will separate. Add one ounce of soap chips to this solution, and this time after shaking, the oil and water will not separate. This shows that oil and water will mix under the proper conditions. MINERAL OIL ` Iu OIL 4 WATER MIXED Mj eet FOOLING YOUR FRIENDS Place two quarts of water in each of two pans and add some salt to one of them. Ask someone to wash his hands in the water to which salt has been added. He will find that try as hefa ^ will, no lather will form, while if yo ' z wash in the plaiy water, an abu MERGUROCHROME 3 DROPS 3 02. LINSEED OIL This burn-aid soap will be found to be a very useful preparation to have on hand in the home at all times. Children particularly are subject to many minor burns, and because of the pink color of the material, they probably will have no objections to having it applied when necessary. Into a glass vessel pour three ounces of lime water (obtainable at the drug store). Add to this, with constant stir- ring, linseed oil until you have incorporated three ounces. Mix thoroughly by shaking, in a six- or eight-ounce bottle. During the shaking, the material will turn to a milky-appearing substance. To this add about ten drops of mercurochrome solution (obtainable at the drug store). This last addition will turn the solution a pink color. These simple experiments will be found interesting and simple for the amateur chemist, and give to the experi- menter a broader knowledge of soap-—one of the most common and useful things in life. While in continual use by every person, few understand its workings other than for washing purposes. 87

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dt | ROD FLATTENED. MINNOW PAIL The ice fisherman’s gear need not be elaborate. All essentials are shown above. Fishing can be done, mechanically, with "tip-ups," or Hand jig- ging, as pictured at right, may be employed. Landing Your Fish ROM our northern snow-belt states, up through Canada and even Alaska, ice- locked rivers, ponds and lakes are dotted in winters with men and fishing outfits. Even snow and bitter winds driving over their frozen surfaces fail to chill the enthusiasm of inveterate fishermen. Despite conservation legislation limiting catches and shortening fishing seasons, in- terest in the sport is definitely on the increase. Many mere onlookers of a Sunday afternoon return the following week-end with the sketchy outfit required to try their skill at ice fishing. Good luck or bad, they usually succumb to the multiple lures of keen frosty air, the contrasting beauty of black evergreens against snow-blanketed hills and the exhilarating feel of lively perch, pike and pickerel tugging against a taut line. Some of the charm of ice fishing lies in its uncertainty. One day you may pull a good string from a single hole, but catch nothing when you hurry back to it the next morning. Fishermen on one side of a pond may be seen frantically pulling in perch, hand over hand, while less fortunates on the other side flail 88 READY-MADE TIP -UPS 4 FISH LINE idle hands and stamp cold feet in an effort to keep warm. i Familiarize yourself with the laws of your particular state as regards ice fishing before gathering your gear together. Yellow perch, - pike, pickerel, whitefish, grayling, bullheads, lake herring and trout, and others, may be taken through the ice—if your particular state permits. Even the methods used—the jigging spoon, tip-ups, “plunking” for ciscos and spreader fishing for smelts—the subject to our everchanging legislation. Ice fishing tackle is characterized by its simplicity. The majority pin their faith to "tip-ups," either buying excellent ready- made affairs at reasonable prices or pattern- ing their own after one or another of the many amateur designs. The ribs from an old umbrella may be used to help make the half-dozen "tip-ups" re- quired. A lath, not quite as long as the rib, is used as a wood support, notched at one end and the rib hung in the groove there by driving a rivet through the side of the notch . and on through the hole in the center of the y The line is tied — . rib to form a T-like affair. to one end of the rib and over the other is

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slipped an adjustable weight such as a lead bullet slug, the rib tip being bent to prevent it from slipping off. The weight should be just sufficient to balance the pull of the set line. A “tell-tale” flag of cloth is tied (preferably to the weighted end) to signal the fisherman of a bite. The support is shaped from a thin 3-inch board, 20 inches long. This is whittled roughly into a wedge-shape and a 1-inch hole bored three-quarters of the distance from the larger end. A 44-inch peg, driven to a tight fit through a hole in the smaller end, permits winding the line for adjusting to the depth of the water being fished, while the “tell- tale" threads through a hole in the other. Use 2-foot broomstick-like poles, with a loose fit through the center hole, for cross arms, so as to lighten the weight of gear to be carried. A tip-up can be made at the pond by lash- -ing two lengths of sapling together in the form of a cross. Tie the line to one end and fasten a handkerchief to the longer length. The disadvantage is that the cross arm may A jigging rod. can be whittled to shape from a stick 18 inches long. ttach a cleat to one end for securing the line. if desired, a leg from an old chair. may be uséd as a jigging rod. “Purchase the spoon ready- B. or cast it from block tin. by Dad Williams CEAD WEIGHT “Tip-ups” need . not be fancy. One made from a length of sapling will serve admirably. This efficient. mechanical ice fishing device 1s easy to make. It is merely an umbrella zib : supported in a notched board driven in ice. A bullet siue, drilled through center, serves -as a counter-balance. Below— “Wip-up?? made from saplings,

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freeze fast to the ice, preventing the "tip-up" from pivoting unless the lashing is on the loose side. Indians merely tie the line to the tip of a strong, supple branch, shove the butt in the snow and slush alongside the hole to freeze fast. The better manufactured "tip-ups" have some sort of spool for the line, so the hooked fish is able to run off with the bait unaware it is fast to anything. Jigging is a more recent method of fishing. The spoon may be purchased in brass, copper or nickel finish, or homemade from block tin molded roughly to the shape of an egg, sliced in half lengthways, a gang hook cast into the smaller end and a hole bored in the other for the line. An 18-inch stick serves as a pole. For this, either a length of hardwood, with a cleated line holder fastened to its butt, or the leg from a discarded chair, with a short length of rung left attached for the same purpose, may be used. “Jigging” is done through a hole in the ice with or without bait- ing the hook. After ascertaining the depth of the water, the line is adjusted to keep the spoon 8 inches off the bottom. From there it is raised another foot, with a jerking motion of the wrist and forearm, to allow it to descend with the spoon fluttering so as to attract the 90 This “tip-up” is one of the simplest to make and most effective. It is merely a length of plywood drilled to receive a broomstick. The line is attached to a peg on one end and the tell-tale flag to the other. Left—A carpenter's chisel, inserted in a length of pipe, provides an excellent tool for chopping through ice. fish. As fish will respond to the upward jerk, as well as to the downward flutter, the fisher- man must be ever alert to strike the hook. Cisco and smelt fishing is carried on in small board or canvas covered shanties, usually as a commercial proposition. In Maine these smelt village shelters are warmed by oil heaters and lighted by lanterns, as much of the fishing is done after dark: spreaders with three or four hooks attached are used. Cisco fishing, as carried out in Lake Geneva, Wisconsin, ice fishing colonies, employs the technique of “plunking” or "tweaking" a bead or minnow baited line through a hole in the ice. Others often choose to fish with a regular rod and summer lures. Finding, playing and bringing the fish successfully through the small hole in the ice demands skill and utmost care. Either minnows or worms are required for effective “tip-up” fishing. Even in coldest weather earth worms may be found in un- frozen ground beneath a sawdust pile or in a farmer’s manure heap. Live minnows on silver shiners are probably best and may be bought at sporting goods stores, near ice fishing locations, or secured from fishermen [Continued on page 134] Modern Mechanix

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Timely Short-Guts For Motorists

Carburetor “Pickling” Adds Mileage N CARS which have seen a considerable amount A PLACED IN TEAPOT of service there is usually evident excessive fuel consumption troubles. In many cases the carburetor is at fault due to the corrosive film accumulating on the inside metal surfaces. To restore the carburetor to its original condition disassemble, place the parts in a muriatie acid bath for a few minutes, wash in a dilute baking soda and water bath and reassemble. Drift Boards For The Garage Doors , HINGED O KEEP drifting snow from packing against the : 7 : X um garage doors construct a pair of folding drift boards cu——À p el oN | E from 12-inch stock. Each of the hinged panels should a AURS IE be about 6 feet high and from 3 to 4 feet wide. Mount juod \ | the boards to the sides of the garage on heavy hinges. Drive stakes in the ground to hold them open during bad weather. The drift boards need not be taken down in Spring as their construction permits them to be folded flat against garage when not in use.—Everett Van Horn.

<a PANELS ABOUT 3x6” 2" oe SD TO1x4* MES

j HINGED TO | | CORNER OF GARAGE

Tape Tabs Aid In Removing Fuses [| ns WRAPPED AROUND HE fuses used in automotive wiring are in nearly every instance mounted in some out of the way loca- tion where they are difficult to get at. To avoid scratched CHOSE fingers when replacing a burned-out fuse in the future, MT HANDLE FUSE attach a strip of tape around the glass tubing to form a small tab. Either medicinal or electrician's tape can be used. The protruding tab provides a firm grip for the fingers and at the same time aids in locating the faulty fuse cartridge.—H. Waychoff.

CANTUS Replacing Switch Type Spark Coils i HEN the ignition coil of the type that combines an ignition lock burns out it can be replaced with an or- dinary type without affecting the operation of the switch. Remove the high tension wire from old coil and place it on “oLD COIL A : z IGNITION SWITCH uf 9 í connect ow so New. Connect one side of new coil to terminal of old where —1 AMMETER 4, GF COIL TO DIS= lin TRIBUTOR , ,4E2| gasoline gauge is con- EE Gs nected and wire other side [Gouna aw iz ; BLADE- of new coil to distributor. GAS GAUGE

Hack Saw Blade Forms Door Handle Tool HACK saw blade ground down to form a hook like the one shown in the accompanying illustration makes a useful tool for removing certain types of window cranks which are secured with a small spring clip.—Wilkie Walter. February, 1938 91

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'The candlestick uprights are formed from two strips of copper, twisted into a spiral column. Template and cross-sec- tion of candle cup is shown. in plan at left. LENGTH BEFORE Q SISTING (I8GA, COPPER) SAUCER BLANK DETAIL OF 3" 3! COLUMN 32 x8 23 UM f b— $—- E: SAUCER ger TOARM] H 1 ROLL AROUND 3/4" DIAM. BAR. FLATTEN 3f DETAIL OF CANDELABRA ROLL AROUND 7/8" DIAM. BAR. The candle cup is hammered to shape over the tip of the anvil, as illustrated in this scene. RODUCING metal articles in the home workshop does not involve the use of expensive bending ma- chines or other costly equipment. The candlesticks, ash tray and picture frame described here are not only easy to make but provide the craftsman with something that he can show his friends with a feeling of satis- faction. Tin snips, ball pein and planishing hammers and an anvil are all you will need in the way of tools. In making metal candlesticks the crafts- man is usually at a loss as to how to form the cups. Also, it is almost impossible to produce an attractive column for a tall candle holder. In the production of the pair of 92 a L f | : ae | SOLDER TO SAUCER} Las i M lon qM ER ae Gu d HAMMERED FOR HOME by Dick ER > Hutchinson Place the upright strips in the vise and twist them to shape by grasping them in the jaws of a wrench. Left-— Hammer the sauc- ers to shape with a ball pein hammer. candelabra illustrated here both of these obstacles have been overcome very beauti- fully. The column for each piece is of -inch sheet copper, 36-inch wide by 1035 inches long. The edges are filed smooth and the pieces hammered. Place two pieces together with the ends even, and set down in the vise 2 inches and clamp. Then, grasp them with a small monkey wrench and twist into a spiral as is illustrated, making it about 3 inches long. The spiral, when twisted tight, Modern Mechanix

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COPPER WARE CRAFTSMEN Ash trays like this one are easy to make. A spring clip holds them securely to the edge of table. The clip may be twisted to form a handle when using the trays in the conventional manner. I Right — Shap- ing bowl on anvil with ball pein hammer. Modern in style is this hammered copper picture frame. Pattern and per- spective are shown below. FIG.2 COMPLETE PICTURE FRAME LAYOUT- i8 GAUGE SOFT COPPER BLANK FOR UPRIGHT (BGA) TRAY BLANK (16 GA. COPPER) Rivet the combination clip and cigarette holder loosely to tray with a No. 14 brass escutcheon pin. February, 1938 BASE BLANK & BEND The metal frame is bent in the vise between hardwood blocks, as illus- trated in the photographs below. will hold together evenly, making a very attractive column. — Bend the two lower exds to shape, and spread out flat with the planishing hammer, drill holes for rivet- ing to base, then bend the other ends out and shape ` as shown. Drill two holes in each for riveting to candle saucers. The base is of 16-gauge sheet copper, 2% inches wide by 8 inches long, hammered and the ends are rolled under. This is done by rolling them around [Continued on page 130]

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Clothes Pin Removes Bulb ANY times a broken bulb is difficult to remove from its socket with- out danger of cut fingers or shocks. A straight clothes pin makes a good tool for removing these broken bulbs without the usual dangers. Slip the prongs over the glass stem, with the tips down into the cavity. The base usually will turn easily. Bend Huproves Plug Contact HEN the contacts of any electrical ap- pliance become worn either by wear or arcing, they may be im- proved by mak- ing a slight bow in the center of one of the ter- minals. This method is useful on all appliances having the flat type of contact. Weight Aids Coil Winding WEIGHT capable of maintaining tension on the wire will be found to be a great help in coil winding. A spring type clothes pin as shown in the drawing will be found satis- factory for attaching the weight to the wire. It should weigh approxi- mately two pounds for best results, and can be made by pouring cement or lead in a short length of gas 94 pipe. Ín use, the coil form is held in the jaws of a vise. After the coil is started, the extra wire is dropped to the floor and the weighted clothes pin is clamped to the wire just high enough to be above the floor. As the wire is used, the weight may be slid down. In this way, a uniform tension is maintained, result- ing in a more even winding. Also, the use of this device permits the operator to have both hands free for the actual winding opera- tion. Hammer Handle Holds Tacks NYONE who has occasion to use several small tacks at a time will find the idea illustrated at the right very useful A small hole is drilled in the handle of the hammer to be used for driving the tacks. The holes can be two or three inches deep. Close the opening with a small cork, and the ham- mer never need be without tacks. The depth of the hole will control the amount of avail- able space for holding the tacks or small nails. Soot Scraper Aids Furnace HEN the water heating pipes inside a furnace become coated with soot they lose à consid- erable amount of their heating efficiency be- cause the layer of soot acts as a heat insulator. An efficient and easy means of keeping these pipes free from Soot is to attach a scraper to them as shown in the drawing. This scraper consists of two iron straps shaped to conform to. the pipe walls, and bolted together between the pipes. A hole in the center is provided so that a poker can be inserted to move the scraper back and forth over the pipes. This action will remove the deposit in a few minutes. Modern Mechanix

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Spring Prevents Lock Loss m n > | | | : ; || | SHORT. STAPLE 7 Hi | SMALL | —E—RH--SPRING | DOOR | | SHUT H X Lock ra | \ | ~~ SPRING Á ISTRETCHED FIG. 1 2 LOCK HELD UP |; & OUT OF WAY HE spring hanger shown in the drawing is a simple way to keep a padlock where it can be found at all times, while it does not interfere with locking the door. Drill a small hole the diameter of the spring wire, through the hook of the lock. Insert the end of the wire and bend it so that it will not slip out. Then fasten the spring, with the lock hang- ing, far enough above the hasp to keep it out of the way when the door is open, but not far enough to prevent it from being pulled down into place when it is needed. Rubber Ball Guards Hands 1. LARGE RUBBER i eon BALL / Se CE Tw. s. j * / m POINTS OF SHEARS t 24 1 ED ^ er NWO PUSHED THROUGH A SHEARS HEMISPHERE TO JOINT ANY times sharp thorns on rose -bushes seriously interfere with the cutting of the flowers, and occasionally painful scratches are the result. By fastening half of a hollow rubber ball over the shears, this difficulty is removed. Use a ball large enough to cover the hand but not so large that it becomes diffi- cult to push it through the bush. After the ball is cut in half, make a small hole where the points of the shears are to pass through. Push February, 1938 the ball over the ends of the blades up to the point where they are fastened together. If the ball is placed either side of the junction, the shears will be hard to open. Bent Metal Holds Brushes BENT STRIP GF SHEET METAL IN CONTAINER WITH OIL KEEPS BRUSHES IN GCOD SHAPE ALLWAYS DIL IN CONTAINER CONTAINER AINT brushes not in use can be kept in good condition by placing them in a con- tainer such as shown in the drawing. The size of the box and the number of folds in the metal will regulate the number of brushes it will hold. The metal need not be of heavy gauge—just heavy enough to maintain the position of the brushes. When the metal is selected, be sure that it is not too wide to per- mit the oil to flow freely around the brushes. Ball Prevents Hammer Slips Tv. N PREVENTS. SLIPPING SOLID RUBBER BALL SCREWED ON HAMM Y FASTENING one-half of a solid rubber ball to the end of a hammer handle, danger of the hammer slipping out of the hand is eliminated. 95

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fT. MICROSCOPE DISCLOSES REAL |NCREDIBLE, but indeed true, the hair of no two of all the thousands of different species of mammals is exactly alike. Amazing, too, that the microscope is an important tool in this great industry as it is in so many others; the limitless powers of this unique instrument seem capable of invading every field. A journey via your microscope into the mysterious domain of fur is certain to prove fascinating. Examination of hairs under a microscope is a meticu- lous business, and yet the technique is very simple. Hairs as obtained from the body or from pelts are dirty and greasy and must be thoroughly cleaned in order to reveal their minute structure which, like the fingerprints of the human hand, affords a positive means of identification. The solution for cleansing is a mixture of equal parts of 95 per cent alcohol and ether. As ether is explosive, keep it away from all flames! Hold one or a few hairs with a pair of fine forceps and wash them back and forth slowly in the fluid for a few minutes. The hairs are next dried over an electric bulb, and are then placed on a scrupulously cleaned slide and capped with a cover glass for tem- porary inspection under the microscope, without any mounting medium. Any dust or dirt interferes seri- ously with determination of the exceedingly fine scales which clothe the exterior of the shaft. If any dust or grease remains on the hair, repeat the cleaning, drying and This photomicrograph of a beaver fur hair illustrates a simple medulla of the discon- tinuous ovate type. Cuticular scales may be seen at the edges. . by Julian D. Corrington, ie Ip 96

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inspection, mounting perfect specimens in balsam. Staining helps bring out the cuticular scales, the best reagent being a saturated solution of safranin in 95 per cent alcohol. This means the maximum quantity of the dry powder that can be dissolved by a given amount of the alcohol. Immerse a hair in this stain for two minutes, then dry as before and mount in thick balsam. Don’t use thin balsam as the stain will run and spread. Hairs are commonly mounted unstained, however, so this procedure may be omitted if desired. Specimens are not at all difficult to collect. Provide yourself with a number of gelatin capsules, preferably the kind that veteri- narians use in putting up horse medicines, and ransack first the various fur pieces be- longing to feminine members of the house- hold such as coats, neck- pieces, trimmings and gloves. It will do these garments no harm at all to remove the three or four hairsthatare needed. In pelts like mink and fox, collect both the over and under fur hairs, which can be mounted together under The protective hair from a mink pelt is shown in the photomicrograph below. It illustrates a simple medulla of the continuous nodose variety as it appears when viewed through microscope. Right—Before mounting on slides, hairs are cleaned in alcohol and ether bath. ANNAN * AA 4 5 : D Ai IIS Jap The fur of the beaver is only one of the many types that is well adapted for examination and study under microscope. the same cover glass. The typical structure in each case is to be found about one-third of the distance outward from base to tip of the entire hair, and this is the portion to put in your capsules for mount- ing. Of course the outer two-thirds or more in many garment furs will already have been removed by clipping, as in Hudson seal, which is trimmed and dyed muskrat, while some hairs even when complete are so short that their en- tire length will go under a cover glass, so these factors have to be taken into account in collecting material. Then come the domestic pets, as cat, rabbit and dog; the farm animals and occasional opportunities offered by unusual captures or pets, and perhaps some friend connected with a zoo or museum can be en- listed in this enterprise. Finally there is the fur store and commercial supply house as sources for the larger slide collections. Pay particular attention to keep hairs from different sources in separate capsules so [Continued on page 122] 97

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ELECTRICAL Kinks Fon Snop Aun Home Button Insulates Socket Pull-Chain FTENTIMES a portion of an electric lamp socket will develop a short circuit on the insulated side of j the line. Accidentally pulling the chain while holding the 777 other hand on a water faucet or standing on a damp | basement floor will result in a noticeable shock. To 5 avoid this danger, cut the pull-chain and insert a small bone button to serve as an insulator. Use fine wire or thread for attaching button to cord.—A. Tempe. Paper Clips Form Handy Switches A FEW thumbtacks and paper clips provide the neces- sary essentials for making inexpensive push and throw switches for use in low voltage electrical experi- ments. Spring each paper clip slightly and attach it to a block of wood with a thumbtack. Another tack mounted about 1% inches from the other serves as the contact. Illustrated are two simple switches. The combinations are unlimited. — H. W. Cardboard Electric Cord Rug Bridge T? KEEP electric cords, which run under carpets, from pulling out of place or breaking down the nap of the fabric, run them under a cardboard bridge. Cut D a strip of corrugated packing carton about 3 inches wide ^ GoRRUGATED _ and the length of the rug, passing the cord between one of y the corrugations. Several pieces of cardboard can be 9 HOLE FORCED THROUGH fastened together with gummed tape if necessary.—V. H. x ed Plumbers' Wool Makes Tight Splices HERE electric wires cannot be satisfactorily spliced LEAD WOOL- BEDDED ; with a soldered joint, plumbers’ wool can be used A TIGHT CONNECTION PONE to insure a good contact. Wrap a small wad of the wool ax around the stripped wires before forming the joint. The resulting splice, if made as shown, will not only be neat, but provide the lasting conductivity of a soldered connection. — A. H. Waychoff, SECTION OF OLO HACKSAW BLADE Hack Saw Blade Insulation Scraper BROKEN hack saw blade attached to a wooden handle and ground down on one side to a knife edge i serves as a handy tool for stripping insulation from heavy j SCD KITCHEN stranded wire. Toothed side is used for scraping.—A. H. : ias SHARPENED 98 Modern Mechanix

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The MM short- peeve The completed trans- mitter. “The oscillator is on the left side of the chassis and the am- plifier at the right. The neutralizing condenser is mounted behind the T55- HE amateur about to go on the air for the first time, or the old timer who took down his antenna when the U. S. entered the war and put it up again after the Armistice, have one thing in common: both want to get as much out of their rigs as possible. Also both want to be able to increase power with a minimum of additional expense. For the beginner, this transmitter offers a n B x B : The antenna coupling unit is shown in the fore- simple and inexpensive means for getting on ground. Condenser at right is connected into the circuit when antenna feeder arrangement requires it. the air with low power—using only the 6L6 oscillator—or with medium power—using the 6L6 to excite a T55 output tube. Designed uses the first thing that comes along for a principally as an exciter unit for a T-125 am- power supply. This procedure is fatal to plifier, to be described in an early issue, this satisfactory transmitter operation. Usually it rig can put a healthy sock in any “sky wire.” is a shock to the builder when he finds that Many times the inexperienced builder gives — 1,200 volts thought to be supplied to the plate considerable thought to the selection of parts of the final actually is but 1,000. Filament for the r.f. section (transmitter proper), but transformers which do not supply the correct February, 1938 99

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The amplifier power supply. 866 filaments. of the r.f. chassis. voltage greatly shorten tube life. Saturated chokes have no filtering value, and they, therefore, might just as well not be in the circuit. The point to be remembered is: Use a power supply capable of delivering its rated output. While emphasis is placed on the selection T1, the plate transformer, is at the right. The filament transformer for the T55 is not shown, as it is mounted near the rear The swinging choke is behind the 866’s. T2 furnishes power for the The bleeder, R5, is shown at the rear. of power supply equipment because this part of the transmitter many times is overlooked, r.f. section components should be selected just as carefully. Nothing is more disturbing than having individual’ parts break down during use. The experienced amateur knows, but the Parts Required 100,000 ohms 1-watt (IRC BT-1) 35,000 ohms 2-watt (IRC BT-2) 10,000 ohms 10-watt (IRC DG) 5,000 ohms 10-watt (IRC DG) 60,000 ohms 200-watt (IRC HOA) 400 ohms 10-watt (IRC DG) .00015 mf. (Cornell Dubilier 4-6T15) .01 mf. (Cornell Dubilier DT-10S1) .01 mf. (Cornell Dubilier DT-10S1) .00014 mf. Hammarlund MC-140-M) .00025 mf. (Cornell Dubilier 4-25T25) .000020 mf. (Hammarlund MC-20-MX) .006 mf. (Cornell Dubilier 4-12D6) .006 mf. (Cornell Dubilier 4-12D6) .00015 mf. (Hammarlund MTC-150-B) .002 mf. (Cornell Dubilier 4-22020) 2 mf. 2000-volt 2 mf. 2000-volt .00035 mf. (Hammarlund TC-350-C) 0-100 milliampere meter 0-50 milliampere meter 0-200 milliampere meter 2.5 mh. choke (Hammarlund CH-X) 2.5 mh. choke (Hammarlund CH-X) T4 7.5 volt 4-ampere center tap (Kenyon T-353) Chl 5-18 Henry swinging choke (Kenyon T-513 Ch2 10 Henry filter choke (Kenyon T-176) 1 Taylor T55 tube 2 Taylor 866 tubes 1 Ratheon 83 tube 1 Ratheon 6L6 tube Xtl holder (ICA No. 414) 3 grid caps (ICA No. 870) Insulating rods (ICA No. 2175) Fuse mounts (2) (ICA No. 2342) Terminal strip (ICA No. 2413, No. 2420) 3 dials (ICA No. 2169) Standoff insulators (ICA No. 2300) Insulex standoff insulators (ICA No. 2338) 8 four-prong sockets (Hammarlund S-4) 1 five-prong socket (Hammarlund S-5) 1 eight-prong socket (Hammarlund S-8) four-prong coil forms (Hammarlund SWF-4) 5 flexible couplings (Hammarlund 81. S2 (ICA No. 1230) 1 metal chassis 10x12x3 (ICA No. 1515)! > standoff insulators with jacks (ICA No. 2304) 2 transmitting plugs (ICA No. 403) 500 milliampere choke (Hammarlund CH-500) Bakelite tubing 6 'x215" (ICA) 1460-0-1460 (Kenyon T-666) 2.5 volt 10-ampere (Kenyon T-360) 6.3 volt 3-ampere cen:-r tap (Kenyon T-351) 100 Miscellaneous wire, bolts, 2 four-prong tube bases 1 or more crystals washers, screws, etc. nuts, Modern Mechanix

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An old tube base is used to connect power leads to the r.f. chassis. Two are used, one for oscillator power supply and one for amplifier supply. DUMMY ANTENNA FOR TESTING OLD TUBE BASE m IGH. VOLTAGE kj) : FILAMENT L5 and L6 are A dummy antenna always should be coupled by one or used when testing the transmitter. L7 two turns of wire should be a coil of approximately six around each coil as : to eight tucns and mounted so that indicated. —— Antenna ANTENNA coupling with L5 may be varied. C13 then is clipped on COUPLING should have a capacitance. L6. Correct position L ANTENNA for clip is deter- UNIT mined by experiment. ; February, 1938 101

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Right—Under view of the r.f. chassis. C5 is the coupling con- denser between the oscillator and the amplifier. Slightly larger or smaller capacity than the one rec- ommended may be found more suitable after experiment. A five- prong socket shown at lower left is used for the crystal holder. Below—-A rear view of the r.f. section. T4, shown at the right, should be mounted near enough to the chassis so that filament leads are as short as possible. Connections from the power sup- plies are made to the sockets shown at the left corner of the chassis. newcomer many times overlooks the fact that a transmitter is far more demanding on its parts than a receiver. Lucky indeed is the “ham” who has not lost a pair of rectifier tubes, a choke or a transformer, when a filter condenser “shorted.” Assuming that the builder has obtained all the parts, the next step is the laying out of the transmitter. While the experienced *ham" probably will have his own ideas as to changes he would like to make, the new- comer will do well to follow the one shown. To anyone contemplating changes we make but one statement: this layout works! Although wood could have been used, the metal chassis was selected because of its shielding properties and snappy appearance. Driling metal is of course a little more troublesome than drilling wood, but if sharp drills are available, the additional effort will be negligible. The set was wired throughout 102 with No. 14 rubber cov- ered wire. Where leads are brought through the chassis, the hole should be considerably larger than the wire to minimize possibility of arcing over. -An even better method is to use feed-through in- sulators. Probably the most troublesome holes to make are those for the sockets. With a saw drill i this operation is simple. If this tool is not available, a series of small holes should be drilled around a circle, and with the help of a chisel to break the metal between the holes, the job becomes much easier than appears at first glance. Two sockets were mounted vertically at the rear instead of binding posts. Two old tube bases are cleaned of class and wires, and are attached permanently to the leads from the power supply. Connecting and discon- necting the set from the power supply then becomes a simple matter. The metal type 6L6 was selected because the oscillator was intended for fundamental frequency. operation only. The T55 can be used as a doubler and still give plenty of output. Inasmuch as a T125 is to be used as a final amplifier, and the T55 will give more than enough excitation even when doubling, the oscillator was kept in the simpler form. [Continued on page 142]

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MODERN MECHANIX PHOTOGRAPHY SECTION PAGES 103-116 FIRST PRIZE-—$15-—goes to Fern France, of Hiawatha, Kan. for "The Singing Lesson", an unusual baby pic- ture. Taken with a Ross reflex camera, 1/25 second at f. 6.3 on supersensitive pan film. North window at child's right, and two photofloods in reflector at left. SECOND PRIZE—310—to Stephen F. Harris, of Dover, Mass., for "A Dog's Life". A lot of patient waiting by the photographer and an exposure of 1/000 second with a Graflex caught this prodigious yawn! Taken in bright sunshine at f.8 on Verichrome film, developed in D-76. Background is piece of black velvet Dads to wall to emphasize the dog's light coloring. OURTH PRIZE-—$5—to Franklin Davis, of Ocilla, Ga., for this difficult shot of a spider in its web. Made at night with a small flashbulb in hand reflector, £.11 on Panatomic film, shutter held open at “B” while flash was set off. Eastman 5x7 camera. A flashlight was used to illuminate the spider while the camera was being focused. THIRD PRIZE--$5-—to John Steiner, Chicago, Ill. Exposure made by putting dish of flash powder on stick and touch- ing it off in the camp fire. Speed Graphic camera, f. 4.5 opening. FIFTH PRIZE —$5—to Grant Russell, St. Louis, Mo., for this wellcomposed scene of two camera fans out for a day in the country. Zeiss Maximar, 1/50 sec. at f.8, with K-1 filter, Panatomic film. MONEY FOR YOUR PICTURES Get busy with your camera and send in unusual pictures of people, animals, machines, trains, airplanes, etc. Each month we will pay $15 for the best picture received from readers, $10 for the second choice, and $5 each for the next three selections. Prints should be glossy, as large as possible up to 8x10 inches (although a small, clear photo is more desirable than a big, fuzzy one) and should be accompanied by the following data: make and size of camera, type of film, and how developed and printed, lens opening and shutter speed, and lighting conditions. Wrap all prints carefully and include postage if you want them returned. Address all contributions to Photography Editor. MODERN MECHANIX, 1501 Broadway, New York, N. Y.

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Constructed of simple and easily secured parts, oto spotlight shown at top wil e you to obtain striking aphic effects through use o eian and light in making spotlight contrast. Steps i : i cutting lens hole in auto «up with scroll saw; (2) bend- as lens-holding brackets which «ut from stiff spring m 2 attaching Sous to tim of with bolts; (4) bolting the 51 swivel in place on sec- ton of stovepipe, 12 inches long, which serves as wall of spotlight. 304. F YOU want to achieve the latest and most modern effects with your indoor photography this winter, you will find a good spotlight almost a necessity. This one is entirely up-to-date both as regards performance and appearance. With it you can make sparkling photographs with bril- liant highlights and rich, black shadows that stand out amazingly from the usual run of medium-tone, gray pictures. Interesting, too, is the appearance of the finished lamp; you will agree that in de- sign and finish it has all that could be asked for in a factory-made article, yet all of the parts are common and inexpen- sive. Exclusive of the lens, you can build this spotlight for less than a dollar, using new parts. The lens will probably cost several dollars more. The first stop will be at the hardware store, for a 12-inch length of 6-inch stove- pipe. This. should be cut from the un- crimped end. You will also need an 8- ' inch piece of !/s-inch brass pipe, threaded at both ends to take a keyless socket and ornamental brass loop which you can get at an electrical supply store. In addition to a friction swivel and various small parts, most of which you can retrieve from the junk box, you will need two automobile hub caps of about a 6-inch diameter. The kind shown in the illustrations are for a popular make of automobile; they fit snugly into the ends of the stove pipe, and being heavy and chromium plated, they make a fine appearance as part of the com- pletely finished spotlight. Most of the constructional and assembly

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details are explained by the photographs. Cut a hole in one hub cap for the plano-convex condenser lens, which you can get at a camera supply house. It is a good plan to first consult a local theatre manager, how- ever. Condenser lenses are no longer used 'on modern high-intensity projectors and can usually be picked up for a small sum. The method of attaching the lens inside the hub - cap, as shown in the accompanying photos, will hold it very securely and yet allow for - expansion due to heat from the photoflood lamp that is used in the finished spotlight. The piece of brass pipe serves as a control rod for focusing the lamp and also as a con- duit for the rubber-covered lamp cord. It passes through a brass bushing which is bolted over a hole in the center of the other The focusing rod bushin wile bolted on the inside of the hub eap (5) and provided wi a simple screw clamp outside (6) to permit easy control. MODERN PHOTO SPOTLIGHT Economical and easy to build, thisspotlight gives excellent performance. p DE Kenneth Murray As an example of what the home- built spotlight can do to provide light and shadow contrast, . study the photo reproduced in circle. 105

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106 A piece of cardboard held in a paper clamp at- tached to end of bent curtain rod, which passes through bushing inserted in hub cap (above). serves as a mask that can be used to vary the amount and shape of beam cast by spotlight. % A practical demonstration of the use of the spotlight is shown above. Illumination from the spotlight, behind the subject, touches the hair, shoulder, and hands. General illumina- tion, to show detail in the shadows, was secured by means of an ordinary floodlamp. al | Pd hub-cap. The bushing should be provided with a screw clamp at the outside so that the control can be held in position once it is focused. When it is withdrawn, removing the photoflood lamp farther from the lens, the light spot will become smaller. Pushing the control all of the way in causes the beam of light to widen until it is almost a flood light, and can in fact be used for that purpose. A unique feature of this spotlight is the light control mask shown in photo 7. This consists of a piece of cardboard held in a paper clamp and adjustable so as to be any distance from the lens. The cardboard can be cut with a mask-opening of any shape so as to vary the amount and shape of the light and secure some really novel effects. The paper clamp which holds the mask is attached to the end of a bent 5c sash or curtain rod, which passes inside the outer sleeve of the rod located in holes between front and rear hub caps. The bushing shown in the illus- tration is merely a brass nut drilled to fit the rod and then soldered over a hole in the front hub cap. The clamping screw, to hold -the mask in any position, passes through a threaded hole in the rim of the hub cap itself. For this purpose the 10c taps and dies sold at 5-and-10c stores are very handy. An ordinary brass swivel was used to mount the spotlight on a metal stand, but you can use any other method, as long as it is possible to tilt the lamp to most any angle. It becomes less effective if the angle is limited, for many of the best effects are secured by throwing the light directly down from above, or directly up from the floor. For utmost flexibility the stand should be adjustable for height. It will be noticed that no provision has been made for ventilation, as it has been found to be unnecessary. The thin stovepipe walls of the lamp radiate the heat quickly. Getting the best results with your spotlight depends on practice as much as anything else; with a little experience and a few failures to your credit, you will have learned to judge the intensity of the light and the darkness of the shadows it casts, and how to balance these with one or more other lights, of the flood- light type, so that the results are striking. As an example of what can be done with the spotlight and one other light to show detail in the shadows, examine the still-life and portrait studies shown with this article. Al- though the spotlight effect is somewhat ex- aggerated in order to provide contrast that will not be lost in reproduction, it gives a hint of the possibilities in this direction. Modern Mechanix

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DARKROOM LAMP Tilis To Any Angle WHE inability of darkroom lamps to tilt is.a serious shortcoming. The need for a tilting device is felt especially in the tray development of films, chloride and bromide papers, where it is necessary to keep a close watch on the formation of the image. Obtain a chalk box having a cover which slides in a groove. The box and the cover are carefully sand papered, and a hole a !2 inch in diameter is drilled in the bottom center of the An adjustable safelight is specially useful when doing tray back. A porcelain socket is screwed development of films, chloride and bromide papers. -This light ^ Spe 3 was built around a wooden box such as used for chalk sticks. in position as shown by the il- lustration. A piece of 3$-inch pine, 3 inches square, is glued ‘OLD CHALK BOX to the bottom of the box. A TRIPOD #;-inch hole is drilled in the TILT TOP center of the block. The ex- terior of the box is stained mahogany or walnut, while the interior is left untouched. Shellac is applied and a 3-foot length of wire is attached to the socket through the hole in the back. A 3-inch square is cut in the Cover Lip inches from the w Components of the safelight are shown here. An opening and a 3-inch square of ground 3 inches square is cut in the chalk box lid, and a piece glass is put in the hole. Cellulose cement is $f 5A Sls re d à porcelain cleat socker and wired used to secure the glass, and adhesive tape through small hole in rear. Assembled light is mounted to $ plaster of paris base by means of a tripod tilt-top. Light [Continued on page 146] source is provided by a 7-watt electric ruby dark-room lamp. Fe. 3! SQUARE 4" SQUARE PLAST- E ROUND GLASS PINE ER OF PARIS -IN BOX COVER BLOCK BASE February, 1938 107

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Measuring the image on the ground ~ glass before photographing to make sure the object will be the right size to correspond with the other print. by Paul Hadley HE making of composite, or combination photos, is one of the simplest branches of trick photography, yet is one which the amateur photographer seldom attempts. Easier by far than the double exposure or distorted perspec- tive pictures, the results are more unusual and bizarre, in that parts of any two or more photos Above: ‘How’s the air up there, big boy?” asks this tiny man of his larger self. Both figures were posed by the same model. Right: “Need for Potato Control!” One tuber like this is a crop all by itself. 108

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may be combined to make a freakish result. Professionals often resort to this method in making “photomontages,” which are often seen in publications. Probably most of you have seen the novelty photo cards in which, for instance, a wagon is seen creaking under the weight of two giant apples which it is carrying to market, or perhaps an ear of corn being loaded on a flat car with a derrick. Many other variations of this type of picture are to be found, all of which were made by the simple method of combin- ing parts of several prints to make a whole. No expensive photographie equip- ment is necessary in making these pictures. One should, of course, use a camera on which the image can be seen full size on the ground glass before making the exposure, and which has sufficient extension of bel- lows to allow copies to be made of the combined prints. The larger size plate of film accommodated by the camera, the better, for this gives The potato was photographed close up, the print cut out, and then pasted on the photo of the man and the wheelbarrow. Scraping the edge of the potato print with a knife or sandpaper to make it thin allows it to be pasted down without a tell-tale line showing. This “prehistoric monster" is simply an enlarged photo of a rhinoceros, on which a smaller photo of the hunter was pasted; the combination was then copied through the : camera. _ you a better chance to study the composition of the picture before making it. A copy lens, which can be purchased from any supply house, will enable you to make closeup photos or copies on cameras which do not have the double extension bellows. The possibilities of composite photos are infinite, and the results you will obtain are limited only by your imagination. The ac- companying illustrations show examples. of a few of the effects. One shows a modern huntsman armed with a repeating rifle about [Continued on page 126] 109

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Owners of vertical enlargers often find it difficult to provide their projection prints with neat borders. Simple Ec : frames formed from 1 by 14-inch lattice strips and ^ TT painted dull black on the inside offer the solution. Placed over the printing paper, they not only serve as masks, but hold the paper flat on'the easel of the enlarger. Pictures of unusual effect can be made by photographing buildings illuminated with floodlights. This picture of the Nebraska Capitol building shows the striking effect of greater height and contrast which would not be evident if photo were made in daylight. The scene was snapped on a cloudy night on super-pan with camera at f. 4.5 with an exposure of 30 sec. Commercial ortho film with 3-minute exposure is also effective for taking outdoor night photos. and D A simple tester for testing flash guns is shown at left. It is merely a 3-volt flashlight bulb inserted in a male attachment plug and wired to prongs. Plug is then inserted in female plug ard screwed into flash gun. Center illustration shows a handy reflector made from crinkled foil attached to a wire frame. Its use will provide better contrast on still subjects taken ihdoors with a time exposure. Use it to reflect light on dark areas. Right—-To move a camera without disturbing the tripod a simple tripod truck formed from light stock can be easily built. Ball-bearing furniture casters permit it to be moved without difficulty. 110 Modern Mechanix

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box to protect it against dust. 'To avoid mixing up black and white "spotting" paints each time a print is retouched, mix up various color tones and deposit on old glass plates from which the gelatin has been removed. File each glass "palette" in a separate film In retouching, se'e't a palette having correct tone and use paint on it to "spot" print. Left—To keep developing solutions at their proper tempera- «ure in cold weather, place tank in bucket of warm water. New ideas and timesavers for the amateur picture-taker and darkroom hobbyist that will add professional A permanent shelf for supporting 2 or 3 glass funnels is a great timesaver when both developer and hypo are to be filtered at the same time. Space holes so that 2 trays or tanks can be placed side by side. Shelf can be fastened to worktable with a short upright. February, 1938 touch to his photographic work. While chemical bottles of uni- form shape and size look nice on the darkroom shelf, it is better Practice to use containers that are physically dif- ferent so that their contents can be instantly rec- ognized when working in dark- ness. Bottles suitable. for de- veloping and fix- ing solutions are shown in photo- graph at left. To obtain soft focus effects on "still" subjects, rotate a loose wad of No. 000 steel wool before camera lens. An exposure of 2 or 3 seconds is suffi- cient for average indoor pictures. 11

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RSS - ME IAMERAS are constructed to be light- tight, and yet in order to make an exposure it is necessary to let light into the camera and onto the film. This requires a special mechanism called the camera shutter. It is so designed that when a release is pressed, it will move, let light into the camera . for a moment or so, and then close and protect the film again from the light. As films have been made more sensitive and shorter ex- posures made possible, the design and con- struction of camera shutters has been improved until today there are shutters that split seconds into almost unbelievably small fractions and let light into the camera for just that fractional part of a second. Most of the smaller hand cameras With which we are familiar are fitted with one, or even both, of two types of shutters. shutter i This is the popular “Compur” used on many cameras. The leaves H which admit light to the negative are : shown here partially open. The num- $ bers around the top outer edge represent i i fractions of a second: 1 is one second, ji 2, 15 second, 5, 6 second, etc. j H The first type is built right next © 2 to the lens, or more properly, be- f tween the elements of the lens. f For this reason it is termed the lens-plane, or more commonly, the “between-the-lens shutter.” The other type of shutter is the focal- plane shutter, so named because of its position right in front of the focal plane or the position occupied by the film in the camera. In aspect, the between-the-lens shutter roughly resembles a doughnut. It consists of a circular metal casing containing the mechanism in such a way that a large circular opening is left in the center. To either end of this opening are attached the cells of the lens, hence the name between-the-lens shutter. The light-tight part of the shutter consists of a set of movable blades or leaves, from three to five to a shutter, which control the length of time that light shall pass through the lens. When closed they overlap tightly and when open they pass out of the central opening into the shutter casing. Early between-the-lens shutters were actuated by a piston working in a cylinder and controlled by an air brake. This type of shutter is quite satisfactory and is still used on large lenses. However, its popularity has recently been over- shadowed by the develop- ment of a newer and more accurate type of shutter of which the Compur is the leading favorite. This shut- ter is’ fitted with a strong spring and a train of gears which controls the action of Upper left—The curtain of the focal- plane shutter showing the slots of varied widths. Center—-Photographic reproduction showing volume of light projected by lens through a between- lens shutter. Below it is a similar re- production of a focal plane shutter. Modern Mechanix

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CAMERA Sj, by T. T. Holden shutter leaves. In some instances this mechanism is so finely adjusted that the leaves open and close in 1/500 of a.second. In the newer rim-set Compur shutter, there is an additional set of gears providing a built-in self-timer which delays the actuating of the shutter for approximately twelve seconds after its release. The shutter casing also contains another set of much smaller leaves which do not close entirely, but which can be moved to produce circular openings of different sizes. These are the leaves of the iris diaphragm, so named because of the similarity of its action and function to the iris of the eye. It will thus be seen that while the shutter leaves control the length of time that light can enter the camera, the diaphragm leaves control the amount of light that can pass through the lens when the shutter leaves are open. When the between-the-lens shutter is tripped or released the leaves must open from the center, allowing light to pass through that part of the lens first, then through the entire lens, and finally through just the center as the leaves close. Yet to stop the motion of the image moving across the film, the total exposure period, or the time elapsing from the instant the shutter leaves start to open until they close, must not be any greater than the time to which the control dial is set. For instance, if the shutter is set for 1/200 of a second, the leaves must open and close in that time. It can be seen that a certain percentage of that time will be consumed by the opening and closing of the leaves, so that light will pass through the entire lens for only a portion of the 1/200 part of a second for which it is set. The advantages of the between-the-lens shutter lie in its relatively compact size, its position on the lens, and the ease with which it may be synchronized with Photoflash lamps. The focal plane shutter in its simplest form, as it appears in the Graflex, Speed Graphic and some of the better grade “minia- ture” cameras, consists of a long curtain or roller-blind. Across this curtain are openings or slots of different widths. When the shutter mechanism is released a slot passes across the film at the back of the camera and light cn- tering the lens can pass through to the film. If the slot is narrow the length of time it will take to pass across any point on the film will be shorter than when a [Continued on page 132] HUOM Sua» Back view of a Graflex camera with the back removed to show the focal-plane shut- ter, with one slot visible. Focal-plane shutters are also used on many small cameras of the so-called “candid” type. February, 1938

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PLYWOOD PANEL GREAT convenience in photography is a simple and certain method of making copies. Especially for those who have no elaborate dark- room, this is quite difficult, Since the average copying de- vice is bulky and hard to store away in an odd corner. The one described and illustrated here folds up into a flat pack- age that slips into a closet or under a bed, sets-up in a moment on any table and fur- ` nishes absolutely standard conditions each time so that exposure may be accurately 114 "CILE Le c E— BE T odo a - E — Nr BOTTOM BOARD a - The copying device pictured above is designed for the amateur photographer who must do his work in limited space. Its use permits photographs, drawings or other illustrations to be copied without loss of detail. Assemble the plywood light boxes and attach to the pivoted arms. Photo mounting board is a plywood panel with battens at- tached at top and bottom. Pivoted arms are screwed to the bottom batten. DEVICE LIGHT- calculated and guesswork eliminated. The copy support is a large piece of plywood nailed to battens top and bottom. On the front are pivoted two arms that swing out from the board as shown and which carry upright boxes at their extremities. These boxes contain two 50-watt bulbs each, top ahd bottom, in porcelain sockets, so arranged that the light shines on the board and not into the lens of the camera. Blocks the same height as the bottom batten on the plywood are attached to ends of the arms, enabling the whole arrangement to stand upright. The camera is mounted on a board that has three rubber feet so it may be shifted forward and backward, yet remain in place when slides are withdrawn, and a spot marked on the plywood on a level with the lens of the camera. Now attach a picture to the board with thumb tacks or transparent scotch [Continued on page 146] ARMS SWING BACK HEN NOT IN USE CAMERA

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See your Harley-Davidson dealer. Get “hep” to the big times and wonderful companion- ship in store for you when you ride this ‘world’s champion motorcycle.. Learn about the fun-packed activities of the local motor- cycle club. Take a ride on a snappy new 1938 model—ask about Easy Payment Plan. Send in the coupon now! Em m EX EE EM EM NM DE EG EGER ER RES REG LEA EE DG GE ED EUG IER LN GA AUD HARLEY-DAVIDSON MOTOR CO., Dept. MM Milwaukee, Wis. Motorcycling sounds like great sport to me. Send illustrated literature and FREE motorcycling magazine, '"The Enthusiast.” No obligation. Postage stamp is enclosed to cover mailing cost, My age is ( ) 16-19 years, ( ) 20-30 years, ( )31 years and up, ( ) under 16 years. Check your age group. When Answering Advertisements Please Mention February Modern Mechanix 115

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Amateur & Photo Puzzlers In this department the Photography Editor will answer any question or problem relating to cameras of all types, enlarging, printing, developing, taking pictures, and the various phases of home movie making. When sending questions to this department, be sure 10 include a stamped, addressed envelope, so that we can answer directly in case space does not permit publication of the question on this page. Send all inquiries to the Photography Editor, Modern Mechanix, 1501 Broudway, New York, N, Y. DISTINGUISHING SCALES ON A CONVERTIBLE LENS There are three diaphragm scales on the shutter of my camera. Just what they are meant to represent I do not know and would therefore appreciate some imformation regarding their use.—Richard Daley, Providence, R. I. The lens on your camera is a convertible type per- mitting the front or rear parts to be used separately. One of the diaphragm scales is for using the entire lens unit, one for using only the front part and the remaining scale for using the rear part of the lens alone. The three scales are undoubtedly marked either with the focal lengths of the different lens combinations or with R (rear), B (back) and F (front) to identify the elements, When using a con- vertable lens as a whole, the element with the longer focal length should always be in front. MEANING OF PROJECTED OR PROCESS BACKGROUND What is meant by a projected or process background? I have often seen these terms used in connection with motion pictures, but do not know just what they refer to.— Arthur Kingsley, Toronto, Ontario. A projected or process background is one in which the image in the background is projected on a transparent screen placed behind the set. The screen is shaded from lights on the set so that the action on the screen and stage are photo- graphed together. In the case of motion pictures, the back- grounds are photographed with a motion picture camera, in the usual way, then projected on the transparent screen from the rear with a powerful projector. The film is, of course, placed in the projector reversed, so that it appears in its correct position when viewed from the opposite side of the screen, Using the projected background, it is possible to bring “location”? scenes into the studio and avoid consider- able expense of sending the company to the actual scene. HOW TO DETERMINE WHEN FIXING BATH IS EXHAUSTED While I realize that hypo solutions may be used over and over again, I would appreciate some information that would be more specific as to its exact life and how to de- termine just when it has become exhausted. Is there any simple way for me to test my hypo solution?—]ohn Sargent, San Francisco, Calif. . In the case of an acid fixing and hardening bath, the time of clearance is a fair indication of the degree of exhaustion, When the time of clearance for a given film is double that required by fresh hypo, the solution should be discarded. Another test consists of adding a few drops of 2 percent solution of potassium iodide to about 34 ounce of fixing bath. If a yellowish coloration forms, the amount of dissolved silver in the solution is sufficient to render its further use questionable. Another test is to fix a small strip of bromide paper for 2 or 3 minutes, rinsing it briefly in water and then im- mersing it in a 1 percent solution of sodium sulphide. The appearance of a brown deposit of silver sulphide indicates the presence of unfixed silver halides which, in turn, shows that the bath is no longer able to function satisfactorily. 116 USING POLAROID SPECTACLES FOR POLARIZING SCREENS Can Polaroid spectacles be used as polarizing screens over the camera lens so as to shield out objectionable re- flections?—Ralph Brown, Philadelphia, Pa. While the use of Polaroid spectacles as filters for shield- ing out objectionable reflections and glare will impair, the definition of the camera lens to a certain extent, excellent experimental results can nevertheless be obtained. ‘An interesting article on the use of Polaroid spectacles, as screens for reducing glare and reflections from pictures, will be found in the January issue of MODERN MECHANIX on pages 108 and 109 under the title, “Polaroid Glasses Make Glareless Pictures." RELATIVE SPEED OF PANCHROMATIC FILM WHEN EXPOSED IN ARTIFICIAL AND DAYLIGHT A photo hobbyist friend of mine says that panchromatic film is faster by tungsten light than by daylight. I am some- what doubtful as to his statement and would appreciate your advice.—Earl Forrand, Des Moines, Iowa. "When photographing a subject free from color the ex- posure speed of panchromatic film is not increased by using a tungsten light in preference to daylight. Although some published speeds may show a shorter exposure under tungsten light, these values have been obtained by comparing the ex- posure required for panchromatic material, with daylight and tungsten illumination, with that required for ordinary blue-sensitive film under the same conditions. As ordinary film is sensitive to only a small portion of the light emitted by tungsten lamps, panchromatic film will be relatively much faster under the same conditions, Never- theless, all panchromatic films in general use are actually faster by daylight than by tungsten. BEST DEVELOPING METHOD In developing my films I have been determining my work by inspecting it in the tray rather than using a fixed time method. It is said in some photographic manuals that only the time and temperature method will work satisfactorily if good results are to be obtained. Is this true?——Marie Wells, Oakland, Calif. Due to the fact that the emulsions of most films are very sensitive to light it is poor practice to examine them under the safelight. Doing this will often fog the image. Speed films as used in night photography should be developed in total darkness. Here it is essential that the time and tem- perature method be used. In all cases develop your films according to instructions printed on developer package. MODERN MECHANIX AWARDS $40 EACH MONTH FOR BEST PHOTOS SUB- MITTED BY READERS The editors of Modern Mechanix distribute $40 in cash awards each month to the five persons who, m their opinion, submit the best pictures suitable for publication in the Modern Mechanix Photography section. Full particulars regarding these awards will be found in this issue on page 103.

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Teeter S eS WAS, y When Answering Advertisements Please Mention February Modern Mechanizr [Spoons at night, there’s a fascinating new world in which to ride your favorite hobby. Scores of exciting pic- ture chances, and an interest- ing technique to learn—gaug- ing distances, placing subjects, arranging lights. You get good pictures, too, from the very start; snapshots at night aren’t difficult—just interestingly different. Equipment is simple. You don’t need a costly camera. Any camera that takes Kodak “SS” Film will do—even a Brownie. With “SS” Film, you use two or three No. 2 Mazda Photoflood lamps, which last for hours, and inexpensive Kodak Handy Reflectors. If your particular camera is equipped with an f.6.3 or faster lens, then No. 1 Photo- floods are powerful enough. FREE BOOKLET... Suggests a variety of picture opportunities ... shows you how to arrange your lights... how to place your subject... tells you everything you need to know about two ways to make night pictures—snapshots with Photoflood lamps, fast exposures with Photoflash lamps. (You can use Photoflash lamps, each good for one picture, if your camera can be set for “time.”’) The directions are simple and easy to under- stand. Get a copy at your dealer's today . . » Eastman Kodak Company, Rochester, N. Y. 117

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Man Makes His Own Rubber [Continued from page 52] conditions that Dr. Nieuwland had used it was possible to convert acetylene to another chemical known as mono- vinyl-acetylene. It was hoped that a good artificial rubber could be made from this chemical, but again the experi- ments were unsuccessful. The chemists who were working on this problem, how- ever, refused to believe that it could not be done, They continued their work, and a few years later they found that by treating mono-vinyl-acetylene with hydrogen chloride gas they could produce a new channel which had never before been made and which they christened chloroprene, Chloroprene is a volatile liquid; it certainly does not bear any resemblance to rubber. But the next and most startling discovery of all was that this liquid chloroprene can easily be converted to a tough, elastic solid. Imagine the elation of the chemists when they found that they had at last produced what chemists had been striving for so many years and had failed to find—an artificial product that is fully equal to natural rubber in strength, toughness and resistance to abrasion. But the real thrill came a few weeks later when they proved that this chloroprene rubber is actually superior to natural rubber in many ways. They had not produced a synthetic rubber but had made something immensely more sen sBle an elastic material that is superior to natural rubber. 'The first step in the manufacture of neoprene is to heat coal and limestone in an electric furnace, producing calcium carbide, designated by chemical symbols as CaCe. The next step is to add water to the calcium carbide and produce acetylene gas (C2H2). ‘There is nothing new about the manufacture of calcium carbide and its conversion to acetylene gas. Everyone who is old enough to remember the early days of the auto- mobile will recall the acetylene generators that were usually mounted on the running board in which grayish lumps of calcium carbide were treated with water, producing the acetylene gas that was burned in the headlights. How- ever, the next step in the manufacture of neoprene: carries us into a new realm of chemistry. Acetylene gas is treated with a catalyst in specially-designed apparatus made of new corrosion-resisting alloys with the result that the acetylene molecules combine with one another to form a previously unknown chemical compound, mono-vinyl- acetylene. Mono-vinyl-acetylene, also a gas, is then put into another catalyst chamber where it is caused to combine with hydrogen chloride gas. The intermarriage of these gases produces another new chemical, chloroprene, which, strange as it may seem, is no longer a gas but a liquid. The final step in this chain of chemical miracles is to subject liquid chloroprene to a polymerization process which causes the molecules to combine, producing a tough, rubber-like solid which is known as neoprene. The perversity of chemical reactions is such that the materials being combined often tend to react not in the desired manner, but to combine in different proportions with the production of unwanted impurities or by-products. The problem of the chemists and engineers who were charged with the responsibility of making this process work was to design equipment and methods of chemical control which would make the reactions follow the desired channe's and produce neoprene having a maximum degree of strength, toughness and elasticity. It was not an easy problem, The first special equipment designed for the job did not work satisfactorily. Changes were made and again the results were disappointing. "The process was further modified and the result was more dis- appointments, but in the end the problem was. solved and now in 1938—seven years after the first experimental factory was built—a huge chemical plant is converting millions of pounds of calcium carbide into neoprene. Ape paratus and equipment unlike anything the chemical in- dustry ever before knew made it possible for manufacturing chemists to direct these reactions in the desired channels, keep them under control, and produce an even better product than was originally made in the chemical laboratory. Neoprene resembles natural rubber more closely than any other artificial product. The X-ray discloses that its physical structure is the same even though its chemical composition is different. It looks like crude rubber shipped from the rubber plantations and is mixed with other materials, processed, and vulcanized by rubber manufac- turers just like the natural product. But although the finest articles look like those made of crude rubber and have the same elasticity, stretch and toughness, they, also have the ability to resist the action of oils, gasolines and solvents which destroy rubber. They resist heat, and direct sunlight does not cause them to check and crack so readily. They resist the passage of gases and have a much longer, useful life than like articles made from nature's product. 118 Science Battles Fog Menace [Continued from page 45] silent period, and a five-second synchronized note. The navigator presses a stopwatch when he hears the start of this radio note, then listens for the fog horn signal. Since for all practical purposes radio signals are trans- mitted instantaneously, while sound travels a sea mile in approximately five and one-half seconds, a simple problem in mental division will give the navigator his approximate distance from the lightship. It is also possible to obtain a stop-watch made especially for this purpose, with the dial graduated into miles instead of seconds. This device works splendidly if the fog horn is heard, but sound waves are notoriously unreliable. All mariners know that a noise that is heard distinctly miles away may be inaudible close at hand. A few years ago a ship ran aground only 200 yards from a fog siren which nobody on board heard, yet the wail of that siren disturbed the slumber of persons on shore twelve miles away. The very atmospheric conditions that produce fog are responsible for this distortion of sound waves, according to Dr. W. J. Humphreys of the U, S. Weather Bureau. Sound travels faster in warm air than in cold. With a thin layer of warm air over the water, and a colder layer above, the bottom of the sound wave will travel faster than the top, thus deflecting the wave upward, just as dragging one foot will turn a sled. If the sound waves encounter another warm layer of air above, the process is reversed, and the sound comes back to the surface, to be heard per- haps miles away. Without the radio as a guide, sound may also be mis- leading as to the direction of its source. Sound waves travel in everwidening circles, like the ripples when a stone is dropped into a still pond. A strong wind will distort tke circle into an elipse. Since the source of sound always appears to be at right angles to the front of the waves, a strong wind might so distort the waves as to make the apparent source as much as 90 degrees from true. By causing echoes, nearby land, or even the front of a [og bank, might also deceive the hearer as to the direction of a sound's true source. The tone of a sound also has much to do with its directional qualities. A very deep note, such as is used on the steam whistles of most of the larger liners, carries a surprising distance, but even in clear air the listener has trouble in identifying the direction from which it comes. A very high note, such as a policeman's whistle, has very high directional qualities, but can be heard a comparatively Short distance. The, Lighthouse Service has been studying the qualities of various tones for years, and attempts to select a note for each fog horn or buoy that will best serve the purpose for the particular location being considered. With a lightship, distance is more important that di- rection, and the fog-horn tone is fairly low. With many buoys in a crowded harbor, direction is usually paramount, so the whistles, bells, gongs and sirens will have a com- paratively high tone. Where both qualities are important, such as with the large sea huoy two miles off the entrance to Ambrose Channel, a delicate compromise has to be reached in the tone of its whistle. Several of the more important lightships, such as Ambrose and Fire Isiand, are equipped with submarine hells and Nantucket Shoals lightship is equipped with an oscillator, synchronized with the radiobeacon signal in the same manner as is the fog horn. Sound travels about 4,800 Íeet per second through water, the speed remaining constant under all conditions. Under-water sounds are not subject to zones of silence, as are sounds transmitted through air, and the waves travel greater distances before dying out. Distance finding by submarine signals is thus íree from some of the uncertainties attached to the transmission of sound in air, although factors having to do with the speed of the ship, the draft, the location of the microphones, etc., are important, and every ship is not equipped to receive such signals. The Olympic was so equipped when it ran down the Nantucket, but that did not prevent a collision. As the name indicates, lightships are equipped with powerful lights in addition to their radio and sound signals, but lights are practically useless in a fog. Large ships must run so fast to maintain steerageway, that when a light is sighted in a heavy fog it is usually too late to stop or turn out of the way. Increasing the strength oí a light seems to have little effect on its power to penetrate a fog. A hundred candlepower light might be seen 100 yards in a particular fog, while a million candlepower light would penetrate the same fog only 200 yards. Another important aid to navigation that makes use of the uniform speed of sound through water is the fathometer. This device consists of an impact oscillator that delivers 2 sound of great intensity through the skin of the ship, a hydrophone to pick up the sound when it returns as an echo from the ocean's floor, an amplifier that changes the [Continued on page 120]

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f pres a POY en Copyright 1938, LicGETT & Myers ToBacco Co. When Answering Advertisements Please Mention February Modern Mechanix 119

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New Black & Decker Utility Power Drills THE new Utility Power Drills are designed for intermittent service, yet have the same high power and high torque as the heavier duty Black & Decker Production Line Units. They speed up and cut costs on hundreds of jobs now being handled by lower-powered service drills—and have the reserve power necessary to economically handle the heavi- est type of work in any shop or plant. Made in 54”, 34" and 7$" sizes. Mail the coupon today for name of the nearest dealer where you can see the new Utility Power Drills—and the many other Black & Decker Electric Tools that are “Helping Good Mechanics do Better Work.” World’s Largest Manufacturer of PORTABLE ELECTRIC TOOLS MAIL THIS COUPON NOW The Black & Decker Mfg. Co., 702 Pennsylvania Ave., Towson, Md. Please send me literature describing the new Utility Power Drills, and the address of my nearest Black & Decker Dealer. Science Battles Fog Menace [Continued from page 118] sound waves into electrical impulses, and an indicator that translates the time interval between sending and receiving into light flashes on a calibrated dial. By taking frequent soundings with a fathometer, the navigator may compare the readings with the chart, and not only know how much water he has under his keel, but have a very good idea of his location. Twenty-four sound- ings a minute may be taken while proceeding at full speed, in contrast to the time-honored method of swinging the hand lead, which required almost ten minutes, with the ship almost stopped, to obtain a sounding. Owing to the extreme speed of sound through water, the fathometer is not accurate enough to be of value when it is needed most—when it is foggy and there are only a few feet of water under the keel. It will show the difference between filteen and seventeen fathoms of water accurately enough, but when it comes down to determining the dif- ference between five and six feet, the navigator must feel his way with the hand lead. en the fog has closed down, and the captain, or the harbor pilot he has picked up, is faced with the ticklish job of bringing the ship through the narrow channels of a harbor entrance, not only the ancient hand lead, but the lowly buoy, are the things he depends upon most. A buoy can be moored out in deep water, close to the track of tlie vessel, without adding another hazard to navigation. Run- ning one down may wreck the buoy, but will do no material damage to the ship. Buoys have !certain characteristics to indicate their posi- tion relative to the channel, or to obstructions. As a ship enters a harbor it will find red, conical-topped buoys, called "nuns," marking the right of the channel, and black, flat-topped buoys, called “cans,” on the left. Isolated middle ground or danger buoys will have stripes of red and black. All will be numbered, odd numbers to the left and even numbers to the right, and these numbers will be indicated on the chart, making it possible to fix the position definitely, once one is sighted. Certain buoys on the right will carry red or white lights. Those on the left will show lights of white or green. Some of the lights will shine steadily, while others will flash for varying periods, making it possible to definitely identify them in the dark, If the fog is so dense that the buoys cannot be seen even close at hand, certain of them will have identifying sounds, such as whistles, gongs, or bells, all sounded by the action of the waves. It is now possible to equip buoys with low- powered radiobeacon transmitters, although the Lighthouse Service has not yet adopted this equipment. Cable com- panies are now successfully using such buoys to mark the ends of severed cables. A fogbound ship entering or leaving a harbor will feel its way slowly from buoy to buoy, following a compass course and keeping track of speed and time accurately. With buoys only half a mile apart, it is seldom one is missed; but if the pilot does miss one, down goes the anchor immediately, Making An Inlaid Footstool [Continued from page 73] Bore the %-inch holes for the leg dowels %4-inch deep around a lightly scribed line on top of the base. A drill press will make short work of this step, insuring even-depth holes and accurate alignment. Sand, rub with steel wool and give a heavy lacquer coat. Be careful to prevent lacquer from getting into the dowel holes. Patting the finish on with the brush held flat will help. Either the jig or band saw can be used to cut out the legs from a pattern shaped as shown in the details. Note that the lower end of each leg sets 1 inch in from the top. Sand all surfaces smooth. Bore the holes 34-inch deep. If a shaper is accessible, slightly round each corner. Lacking this, sand off the sharp edges. Glue the top in place first, align the legs by sighting along pairs, then glue the base in position. Cut off the remainder of the knob left when recessing the base, at the center, with a chisel. 120 Accept No Substitutes! Akoays Insist on the Advertised Brand!

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ae U ae © mplete 1938 Radio Catalog. Every- thing in radio in one great book, at lowest prices—164 pages of Sets, Parts, Kits, Sound Systems, Amateur Gear, Test Equip- ment, Books, Tools, etc.—every Radio requirement at your fingertips for instant reference—-easy to use and profitable to order from. For ALLIED's complete stocks and fast service save you time—and ALLIED’s low prices save you money. Send coupon today for ALLIED’s free 1938 Catalog—Radio's Com- plete Supply Guide! e e 8? IP TM T. eo PL SF D A AT STARTLING LOW PRICES ! In KNIGHT Radios, ALLIED brings you Push-Button Tuning and every other newest feature at prices that fit every- body's purse! Advanced R.C.A. and Hazeltine licensed circuits, World-Wide Range, Push-Button Tuning, Select-O-Matic Slide-Rule Dials, Electric Eye, New A.F.C. Action, Giant Elec- tro-Dynamic Speakers, Broadcast Studio Tone Quality, Dual Tone Control—all these and more, at far less than you'd expect to pay. Only ALLIED’s volume and low distribution costs make these values possible. 61 great KNIGHT models to choose from —a set for every purpose—for AC, AC-DC, 6 Volt, 32 Volt, Battery and Auto operation. See them all in ALLIED's Catalog now—just send coupon! . 6-B 1 Send your Free 1938 Cataloz. Send Free Parts Lists for Name Address City... state When Answering Advertisements Please Mention February Modern Mechanix 121

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x | et have found in microscopy a fascinating per- sonal home hobby. A new 20- page booklet tells what to look for through a microscope, how to begin your exploration into the mystic unseen world. Write for your free copy today. At left, precision Bausch & Lomb Model R Microscope, 75 to 300 power, with 455-page book. $21 Book alone, $5.00. Other 9 microscopes, $ 14.50t0$774.50. BAUSCH & LOMB 231 BAUSCH ST., ROCHESTER, N. Y BAUSCH & LOMB MICROSCOPES do-it-with-squabs à. & national ‘markets are wide open for all the SQUABS you can ship, every day in the year? We give a large bonus in stock for promptness. Write today to RICE FARM, 602 H St., Melrose, Mass. SHAMED BY PIMPLES AT 17? Keep your blood free of pimple- making adolescent poisons Don't let your face be blotched with ugly hickies! Stop being shunned and laughed at! Learn the cause of your trouble and start correcting it now! Between the ages of 18 and 25, vital glands are de- veloping, helping you gain full manhood or woman- hood. These gland changes upset the system. Poisons are thrown into your blood . . . and bubble out of your skin in hated pimples. Resolve to rid your skin of these adolescent pim- ples. Thousands have succeeded by eating Fleisch- mann's Yeast, three cakes a day. Each cake is made up of millions of tiny, active, living yeast plants that fight pimple-making poisons at their source in the intestines and help heal your skin, making it smooth znd attractive. Many get amazing results in 30 days or less. Start eating Fleisehmann's Yeast today! Copyright, 1937, Standard Brands Incorporated demand and markets up. Write a_post-card, get FREE EYE. OPENING Picture Book. Why breed for Supply low, 122 Accept No Substitutes! Discloses Identity In Fur [Continued from page 97] as to avoid mixing; include a tiny slip with the animal’s name written in India ink or else a key number referring to a card index record. In making identifications, begin with a study of the outermost layer of a hair, the cuticle. This sheath is made up of a great number of minute scales which vary in their disposition and shape. Two main types are recognized, the imbricate and coronal Imbricate scales overlap around the hair shaít, there being more than one encountered in making a circumference; coronal scales encircle the shaft as a continuous band, oíten presenting the appearance of a crown. Both types are shingled, the lower scales over-. lapping the upper. Subdivisions are named according to the shape of indi- vidual scales. Among imbricate scales are the ovate (oval in outline), acuminate (pointed), elongate (larger and longer than the acuminate), crenate (notched or wavy out- line) and flattened (like ovate but very low and flat), The crenate variety is commonest of all and the flattened is also often encountered. Sparse hair and coarse or spiny hairs are invariably of the flattened type. Coronal scales are designated according to the appearance of the border as simple (plain border), serrate (edge saw- toothed) or dentate (bluntly-toothed), The first two of these are characteristic of various bats and because of their beautiful appearance under the microscope, bat hair is in demand by microscopists. “Mink and otter exhibit the dentate pattern. Next below the cuticle comes the cortex (bark), com- posed of spindle-shaped cells that are so compact the whole layer appears transparent and uniform. Keratin, or horn similar to that of our finger nai!s, is deposited among these cells and gives to the hair shaft its characteristic cornified (horny) appearance. Also in this layer occur various pig- ments granules, usually responsible for the color of hair. These granules are scattered between and within the cortical cells in a fairly regular design that is sometimes of aid in making identifications. Lastly there is the innermost part, the medulla (pith), with its material disposed in a column running lengthwise of the hair shaft. In this column are sundry shrunken cells, spaces and dried and horny epidermal structures, the pat- tern of which is characteristic of each species, Unstained hairs are necessary for microscopic examination of either cortex or medulla and so if stained specimens are uscd for study of the scales, mount both stained and unstained ma- terial on the same slide, so that complete determinations can be made. . Medullas are classified first of all as simple or compound. Simple medullas have only a single strand of material run- ning through the hair and comprise three types: continuous (a more or less solid rod), fragmental (isolated patches probably resulting from a breakdown of the continuous type) and discontinuous (separate blocks lying one above another, regular in arrangement). The compound medulla is rare and shows two or more parallel columns of the dis- continuous style, side by side. Shapes of the individual elements of these conditions are described with terms like those used with the scales. Thus one may have a simple discontinuous ovate medulla, the word ovate referring to the shape of a single medullary block. Continuous medullas are either homogeneous (straight and plain) or nodose (with constrictions or irregular outline). Color of a hair specimen is sometimes helpful in identifi- cation, though since it varies with sex, age or part of body in many species, differs throughout the extent of a single hair, and 1s easily altered with dyes, it is of only minor importance. Size and particularly average ranges of size are used somewhat, being more or less constant within known limits. These diameters are measured in microns and determined hy means of a micrometer eyepiece. With all this data at immediate disposal, nature of cuticular scales, pigment g-anules of the cortex, medullary structure, éclor and size, it may readily be appreciated that many thousands of combinations of all of these factors are possible and that the hair of no two species of mammals will he exactly alike. Make your own sketch drawings of the cuticular scales and types of medullas. on cards and file these by sca'e pat- tern, cross-referenced to medulla and to a file of the mammals listed by name, arranged alphabetically. Do this only for those species of whose identity you are positive. For keys by which unknowns may be identified, see one of the two following articles: Hausman, L. A., “Structural Characteristics of the Hair of Mammals.” The American Naturalist, Vol. LIV, Nev.-Dec., 1920, pages 496-523, or by tke same author, “Mammal Tur Under the Microscope,” Natural History, Vol XX, No. 4, 1920, pages 434-444. These journals are on file in the larger public and college libraries, Always Insist on the Advertised Brand!

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Let Engineer Dobe E Show YOU How fo Get a , BETTER JOB end MORE PAY Engineer Dobe can prepare you just as he has trained thousands of successful students, aged 16 to 18 to past 50. His practical ‘‘Work-Job’’ method requires no previous experience. High school edu- cation not needed. He offers you a real opportunity to get 2 complete training in drafting right in your home in a surprisingly few months. Trained draftsmen enjoy good salaries. Engineer E| Dobe teaches his students until 2 thoroughly trained and until | holding a good paying job. That's Engineer Dobe's guarantee. Send for FREE BOOK Mail the coupon today for FREE illus- 4 trated book "Successful Draftsmanship'' and full details of Engineer Dobe's re- markable trial.offer that includes all necessary tools and equipment. Learn just how you can be trained successfully 7} at.home in your spare time. Time is money. Now is the time to prepare. Don't waitanother day. Send thecoupon NOW for Engineer Dobe's FREE Book. ENGINEER DOBE Div. 4732 Libertyville, II. When Answering Advertisements Please Mention February Modern. Mechanix If you want to learn drafting asa profession—or if you want to learn drafting to advance in your present work—Engineer Dobe can train you at home in your spare time by his long established, ' proven-practical 'Work-Job'' Method. A . knowledge of drafting is a vital aid to your suc- j cess—for all modern industry begins with the draftsman. The drafting room is the nerve center of manufacturing, building and transportation. New inventions, new designs, new plans, basic improvements must begin with the draftsman. Heis the key man of our industrial system—with rich opportunities for advancement and better pay in scores of fields. In Machinery, Building, Aviation, Elec- tricity, Transportation, Automotives—draftsmen must be used. Many trained draftsmen will be needed on better jobs at better pay and shorter hours. DRAFTING at Home You'll be amazed at the speed with which you can learn in your spare time by Engineer Dobe’s Practical Method. Send coupon TODAY for free book entitled “Success in Draftsmanship.” All Working Tools Furnished Complete Outfit, size 20x25", furnished to you. Here’s a draftsman’s set of tools—sent at once (also a drawing table) — all without extra charge the day you enroll. - è = p ü | ENGINEER DOBE, Div. 4732 Libertyville, ll. g E Send me your free book “Successful Draftsmanship", B I Please explain how you assist your graduates to good B H positions as draftsmen. H ' ING ohio ee Eee ee A EPEN TEE OE A i - E --———————— H sar ee es ie eee IMEEM 5 H TO --- me RT TLree H H State.-.-.-~----------------------- +--+ +--+ Age .-___----- a 123

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MORE POWER TO YOUR SHOP WITH THESE è e IM 6) POWER TOOLS BY DRIVER Direct drive, from motor to saw blade, without belts or pulleys—saves up to 40% of your motor's power formerly wasted by belts, and economical to operate. Efficient, sturdy DIRECT DRIVE MJ917 The combination of the three most JIG SAW $48.50 outstanding features since the in- vention of jig saws makes this ma- chine a pleasure to operate. Direct Drive—built-in drive means more power, no belts to slip. Fingertip Speed Control—a flip of a switch from low to high speed while tunning. Motion Blade Tensioner —permits accurate tensioning of lade while in operation, Same model with single speed (774) priced at $38.50. GEAR DRIVE 999 TILTING ARBOR SAW $72.30 (without motor unit) The tilting 8” blade gives you full 2” depth of cut, at any angle, The big table is always level; unwieldy stock is easy to handle, And the new Geared Motor Drive assures increased power transmission to the saw blade, preventing stalling even under heavy cuts, Precision con- trols, sealed ball bearings, handy control switch, The 1100 series, with [0" blade, also available at $107.25 (less motor unit), Driver makes three lines of lathes, bench saws, band saws, jointers, drill presses, flexible shaft grinders, bench grinders, surfacers, and a complete line of motors and accessories. Send for your 1938 Driver Catalog and examine the many features of the year’s most important tool developments. Walker- Turner Co., Inc., 528 South Ave., Plainfield, N. J. ete VEINS 124 Build This Sturdy Band Saw [Continued from page 83] manner indicated on the drawings or by some similar means. The packer bearing used for this purpose on the original was taken from an old grain binder. Slots should be provided in the frame to permit alignment of the wheels. These are not shown in the drawings but are essential! The blade guard may be two brake bands riveted together (see Fig. 9) and passed round the drums as shown in the drawings. A handsome table can be made by alternating strips of black walnut and maple as shown in Fig. 1. Assemble with %-inch dowels and glue with water-proof casein glue. The table is sup- ported by a column which is simply a Ford T connecting rod. The journal end is bolted to the saw frame from beneath the frame. The table pivots on an Overland piston pin which is clamped into the upper end of the connecting rod. The brackets used to pivot the table on this pin are shown in Fig. 1. The upper half of each bracket is screwed into the bottom of the table, exact position being determined on the job. The lower guide roller is part of the table column assembly. As shown in Figs. 1 and 7, a steel roller is pinned to the piston pin and is adjusted by sliding the column on the frame and the piston pin in and out of its anchorage. The upper guide assembly is clearly shown in Fig. 6 and requires but little explanation. A length of 54-inch steel rod slides in the collar and may be held in any desired position by means of an adjustment screw. At the lower end a piston pin is anchored and in turn carries two rollers which engage the saw blade. The fitting used to secure the piston pin on the original was a casting taken from an old grain binder. A satisfactory and practical substitute is shown. The *s-inch rod is traversed to fit the 14-inch pipe tee, and the piston pin slides in the tranverse portion. Ream the pipe to fit the piston pin if it is too large and bush the tee with babbit if the pin comes too small. Slots cut into the saw frame as shown permit the entire guide arm to be adjusted in line with the lower guide. The rollers were taken from push rods off an old tractor. The tension of the blade is adjusted by means of the 44-inch pipe previously mentioned. The lower end of this pipe rests over a 12-inch bolt which is screwed into the frame and projects for this purpose. At the top of the frame a ?s-inch bolt is used with a slight shoulder turned into it as shown in the detail sketch on Fig. 5. This bolt bears down to fit inside the pipe, the shoulder bearing on the pipe edge itself. Turning the bolt thus forces the frame apart to increase the blade tension. By means of a spectograph—an optical instru- ment—very tiny amounts of lead in the brain of an individual can be detected. Accept No Substitutes! Always Insist on the Advertised Brand!

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NY tits RADIO? . . DOES THE FUTURE OF TELEVISION Interest You ? ^. SEND FOR YOUR FREE cory | OF THIS BOOK OF FACTS 4 Full of Instructive Information on Employ- ment Opportunities and Requirements You men who are sincerely ambitious to make good in radio and related in- dustries will want a copy of this new beak about employment opportunities and requirements. Written in plain, understand- able language with no exaggerations and no mis- statements, this free book gives you facts you want to know about these profitable trades. 95 illustrations. Major subjects include Television Theory and Construction, Pick-up Systems, Ampiimers. Transmitters, Receivers, Cathode Tubes. Sound-Recording on disc, Loud Speakers, Talking Picture Projection and Radio Cem- munication. Many students can earn room and board while learning. National students are allowed coach railroad fare from any point in the United States te L. 4. REQUEST FOR FREE BOOK NATIONAL SCHOOLS (established 1905) Dept. MMR-2 4000 S. Figueroa St., Los Angeles Please send me, without obligation, your FREE BOOK and information regarding Radio and Television Employment Opportunities and NATIONAT SCHOOLS c story building, exclusively mien. Latest equipment. engineers and instructors. NATIONAL fs cwn modern three- x ng ambitious experienced stof of LA Se Reguirements. NAME. AGE____ SCHOOLS use — i Los Png eles CITY — ~ STATE ESENES ED EDS ENED ENEN ED EDS ES EDEA PENEDEN EMED EDEDED OLDEST TRADE INSTITUTION IN THE WEST— EST. 1905 E E a NI C IS When Answering Advertisements Please Mention Februcry Modern Mechanix 125

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FIXED FOR 1A LIFETIME Now you can make home repairs with CASCO, the same glue used by Master Woodworkers € No more gluing failures! Now permanently fix broken furniture, loose linoleum, toys, luggage, any- thing that needs gluing...and get the same weather- proof CASCO joints that leading manufacturers use in building custom furniture, pianos, airplanes. EASY TO USE. Just mix one part CASCO powder in one part water, and it’s ready to apply. No mess. No heating, And no waste... you mix it as you need it. PERMANENT. CASCO sets chemically like concrete. It's not loosened by atmospheric heat and moisture like ordi- nary evaporation-setting glues. ECONOMICAL. CASCO plus cold water makes a full- strength glue at less cost than ordinary l qua glues. More than a glue, CASCO has many hous uses. (Send for the free book offered below.) AMAZING EVIDENCE of CASCO’S Moistureproof Strength: "LOST 11 YEARS UNDER WATER, the 84-inch hull of the model yacht ‘Witch’ was recov- ered, washed, and found to be in excel- lent condition. The CASCO-glued con- struction was strongas ever..." (Johu Black, Watertown, Mass.) FREE! NEW 1938 CASCO GLUING GUIDE! 32 pages, 40 pictures, the book that saves dollars in repair bills: How to make— Sizing Water-Resistant Paint Tile Cement Crack Filler How to repair— Furniture Musical instruments Sports Equipment Automobile Tops Airplanes Swedish Putty Gliders Tralters New ways for— Boats Erecting Fibreboard Luggage Veneering Books Fiush Door Construction Send for your copy now. Jost write your name and address and the words *' Gluind Guide'' on the back of a penny postcard. and mail to— CASEIN COMPANY OFAMERICA, INC. Dept.M.M.238, 350 Madison Ave., NewYork WEATHERPROOF POWDERED CASEIN GLUE 4 Handy Sizes —10c to 65c— At Your Hardware Dealer’s Composite Photography [Continued from page 109] to do battle with a “prehistoric” monster which appears to tower far above the man as it comes over the brow of a hill. In making this picture, the first step was to make the picture of the bug. For this purpose, a dead rhinoceros beetle was obtained from a bug collection and placed upon a small square of sod set upon the studio table. A white cardboard background appears as sky, and the towering effect was obtained by placing the camera lens an inch or two lower than the bug, and pointing up at it. A time exposure by the light of a window produced this first nega- tive. The next thing done was to get the picture of the hunter. Carefully measuring on the bug negative the height at Which I wished the hunter to be, a second negative was made, (outdoors) of the man, getting far enough away to get an image of the size to correspond with the idea oi the picture, This was ascertained by measuring the image of the hunter on the ground glass with a small ruler before inserting the plate and making the exposure. When prints of both negatives had been made, the figure of the man and gun was cut out with a scissors, scraped to extreme thinness at the edge, and pasted to the suríace of the bug print. This was then copied exact size through the same Camera on process film to obtain good contrast, The procedure was exactly the same with all the other pictures, In the potato view, the man pushing the wheel- barrow was made first, then the potato photo raphed to correct size, and pasted on. The man shaking lands with his tiny counterpart is another ena of what can be done, in this case both photos being taken out of doors, with the light coming from the same direction. This is one thing that should be noted when selecting pictures to be combined together—the lighting should be coming from the same, or “nearly the same, direction in both prints. To go back to the print of the bug and hunter, notice how the light is coming from in back of the bug and striking the hunter in the face, as though both coming from the same source, yet one was made outdoors, the other in the house. Scraping the edge of the print, as illustrated in one of the photos and mentioned before, is done to make the edge extremely thin, so it will lie as flush as possible with the surface of the larger print when pasted down. This will eliminate the possibility of the edge of the paper showing in the copy as a light or dark line. The edge may be scraped with a razor blade, or even rubbed down with fine sandpaper, but of course you should be careful not to wear down or remove bits of the edge of the picture itself. A few other effects possible, just to start your imagination to working, would be to have a large image of yourself towering above your home, which is reduced in size to look like a small doll house. Or to reverse the procedure. you could be small enough when placed upon your doorstep to make the house look like the abode of a giant. If you are a flower or garden enthusiast, have a picture of yourself walking through your garden, with the blooms oi the poppies towering far above your head, or show yourself attacking one of your cornstalks with an axe. A fisherman could be shown with a trout or bass being brought home on a truck, as an example of one that did not get awav. But such bizarre examples are not the only uses to which combination photography may be used. If you have photos of two or more of your friends or relatives taken separatively, these may be combined into one picture to look as though they were all taken together. Size oi the different prints does not matter, as the images may be reduced or enlarged in the camera to correspond. Another thing that is important is copying the prints to obtain even lighting. Of course, if you have regular copy- ing equipment, this becomes a simple matter, as the light- ing is part of the equipment. Any camera with a ground glass back and which uses plate or film holders may be used for copying. Extending the bellows to full length enables you to get up close enough to the print to get a large copy. he camera should be set on a table or tripod, and the print on any suitable support, so it is eractly parallel to the ground glass, and centered with the lens. By having tbe print directly facing the window, flat lighting may be obtained, or by placing the camera so light will fall on it evenly from two windows. By doing the latter, you will have no difficulty in light reflections from the suríace of glossy prints, which sometimes ruin the copy. Ordinary film or plates are not suitable for making the copy negatives, as they do not have enough contrast. Special film and plates, known variously, as slow, copy, or process, have much more contrast, and are obtainable for any plate camera, These films are from five to ten times slower, how- ever, than regular film, so give from five to ten times the exposure. As a rule, these films and plates give more con- trast with overexposure than with underexposure. All the photos illustrating this article were made this way. The originals were on regular portrait film, the finished combi- nation copies on process film. 126 Accept No Substitutes! Alwavs Insist on the Advertised Brand!

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*[ buried manuscript unseen in a vault. It is in a monument. In imitation of mummies I wrapped important comic, tragic, philosophic and mathe- matic writings in paper, in a bag, in sycamore wood. If I am dead, do not discover it, until a century is past; reburie it." So wrote Francis Bacon, renowned mystic and unknown author of Shakespeare's plays. in a cryptic code over three hundred years ago. Haunted every hour of his life for the secret of his uncanny power to probe the mysteries of life and his strange ability to accomplish miracles, the world now seeks his long-lost manuscript. From what strange source came his wisdom? Had he received the great knowledge of the ancients as a heritage? While eerie cemeteries and ghastly churchyards are being scoured by the curious, fifty thousand men and women, in the privacy of their homes, in every nook and corner of the world, are sharing quietly the tremendous advantages of his concealed wisdom. Not in crypts or vaults did they find these rare truths of nature he taught, but by sharing the teachings of the secret brotherhood with which he had long been associated. If you have the worthy desire to master life, to develop a confidence that comes from under- standing. and to acquire a dominant power by which to When Answering Advertisements Please Mention February Modern Mechanig Has the Greatest Manuscript Ever Lost, Been Found ? hat Strange isdom Lies | 9 overcome adverse circumstances and rise about your envi- ronment, then this great heritage of wisdom may be yours, Accept this Gift Book Thousands have been led by it toa greater mastery of life. For centuries the Rosicrucians (NOT a religious organi- zation) have perpetuated the teachings which Bacon pri- vately taught. Use the coupon below and receive the free, inspiring book of full explanation, “The Secret Heritage. The ROSICRUCIANS CAMORC) USE THIS COUPON Scribe B.S.Z. The Rosicrucians, AMORC, San Jose, California. I am sincerely interested in knowing more about these helpful teachings. Please send me, without . obligation, the book, “The Secret Heritage,” which I will read as directed.

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GIRLS DESPISED HIS SKINNY, PIMPLY LOOKS but now he's gained 21 POUNDS ; and new popularity Roy Rigby "At parties I felt like a back number. I was so skinny and my face was so broken out with pimples that none of the girls ever noticed me. On the advice of a friend I started taking lronized Yeast. In 12 weeks I gained 21 pounds and my face began to clear up and take on a healthy color. I’m strong as an ox now and so popular that the fellows call me a ‘Ladies’ Man’.”’ T Rey Rigby, De Kalb, IIl. Posed by professional models SKINNY? Thousands gain 10 to 25 Ibs. with new IRONIZED YEAST tablets N? longer need thousands remain skinny and friendless, even if they never could gain before. Here's a new easy method for them that puts on pounds of naturally attractive flesh—in just efewweeks! Scientists have discovered that hosts of people are thin and rundown simply because they do not get enough Vitamin B and iron in their daily food, Without these vital elements you may lack appetite and not get the most body-building good out of what you eat. One of the world's riehest sources of health-building Vitamin B is the special yeast used in making English ale. Now hy a new costly process, this rich yeast is concentrated 7 times, taklng 7 pounds of yeast to make just one pound of concen- trate—thus making it many times more powerful in Vitamin B strength than ordinary yeast! It is then combined with 3 kinds of strength-building iron (organic, inorganic and hemoglobin iron); also pasteurized English ale yeast. Finally, for your protectlon and benefit, every hatch of Ironized Yeast is tested and retested biologi- cally for its Vitamin B strength. This insures its full weight- building power. The result is these new easy-to-take little Ironized Yeast tablets which have helped thousands of skinny people who needed their vital elements quickly to gain normally attractive flesh and peppy health. Make this money-back test Tf, with the very first package of Ironized Yeast, rou don't begin to eat better and to got more benefit from your food—if you don’t feel better, with more strength, pep and energy—if you are not convinced that Íronized Yeast will give you the pounds of normally attractive flesh you need—the price of this first package will he promptly refunded. So get Ironized Yeast tablets from your druggist today. Special offer! To start thousands building up their health right away, we make this valuable special offer. Purchase a package of lronized Yeast tablets at once, cut out the seal on the box and mail it to us with & clipping of this paragraph. We will send you a fascinating new book on health, “New Facts About Your Body." Remember, results with the very first package—or money refunded, At all druggists. Ironized Yeast Co., Inc., Dept. 562, Atlanta, Ga. WARNING: Beware of the many cheap substitutes. Be sure you get the genuine Ironized Yeast. 128 You Can Learn Glass Blowing [Continued from page 78] bulb with walls so thin that they immediately collapsed. This is avoided by gathering the glass so as to thicken the walls of the tubing. As an experiment, heat the middle cf a short piece of glass, and while rotating it uniformly, gradually and carefully bring the hands together. This must be done slowly and with judgment. You will find that the walls of the heated part of the tubing will become thicker and, if you wish, the bore can be entirely closed. Cork the end of one spindle and blow gently into the other, meanwhile continuing the rotation. The heated glass will expand into a more or less perfect bulb, according to the amount of skill you have acquired, and the walls will be thick enough for practical use. In this connection, the blowing of different sizes and shapes of bulbs in a single piece of tubing is excellent practice and will provide skill in handling glass. Making a Beverage Sipper: A glass "straw" for sipping cool drinks is an easy project to commence with, and they make very attractive and useful bridge prizes. Choose a piece of narrow tubing and heat one end until a considerable amount of glass has been gathered. Blow into it very genily to form a thick-walled bulb about 34-inch in diameter, then while the glass is still hot, almost flatten it with a tweezer- like tool made by bending in half a narrow piece of spring brass. Suction applied to the open end of the tube will make the sides of the flattened bulb concave. Heat and bend it at an angle to the stem, then heat a small spot, blow hard into the tubing and a hole will be formed. This can be made smooth by further heating. Make the stem to the desired length by cutting it with a triangular file and then tapping, when it will part neatly. Heat the mouth of the stem to smooth and round it. The stem can be heated and bent in the middle if desired. Flower Vase: Cut a 12-inch piece of your largest tubing and at 3 inches from one end gather the glass together, closing the bore, to form the stem. Gather more glass im- mediately next to the stem, then gently blow it cüt into a small bulb. Before the glass has cooled, bring the hands to- gether so as to "squeeze" the bulb to shape. Bicw six more bulbs, closely adjoining, in the same manner. The ends are flared, to form a base and mouth respectively. Ly rcetating the heated glass against a spear-shaped tool made cf sheet steel or heavy brass. Lips are formed around the mouth with a sharp corner of a putty knife ground to a triangular shape. A distinguishing feature of handmade work is tkat it i seldom uniform, otherwise it would be in the same machine-blown glassware. For this reason it is not x or advisable, to try to make the vase absolutely pez: Uncle Sam — Model Maker [Continued from page 60] of tiny model buildings, the largest of which rcp an 80-ft. building, is but one-half inch high; yet exact scale! The CCC boys spent four months bu modcl. Historic battlefields of the East are being re in miniature, so that students of history, military just plain citizens can understand more readily s highly important events that have helped shape ths of the United States. Tn all, the making of models and relief maps primarily as a relief project, has proved to while investment. Those in contact with the w that the money to be saved by the models conjunction with the building of roads, fightin planting trees and doing other things in the 4 eventually will pay for the work many times cve Nearly al of the actual labor of buildi maps is done by CCC boys who, when first model laboratories, are totally unfamiliar work. The skill developed by many of these yc comparatively short time continues to amaze e perienced technicians who supervise the work The making of a relief map proves to le « interesting processes. These maps are based maps and surveys that already have le maps on which winding lines show the cc of every point in the region. First the scale of the relief map is determined, and card- board of the proper thickness selected for building up the form. Thus, if a map whose contour lines represent dif- ferences in elevation of 50 ft. is to be reproduced or a scale of 1 in. equals 500 ft., cardboard 1,10 in. thick would be employed. exacting men ina > the ex- ci the most icpographic made, paper cur and height [Continued on page 130] Accept No Substitutes! Always Insist on the Advertised Brand!

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THE BEST MOTORCYCLE “BUYS” FOR 1938 WHO BUT INDIAN could bring you engineering triumphs like these new 1938 motorcycles at such smashingly low prices! These great new Indians have everything — easy handling, power, pep, economy, and all the thrill and adventure of motorcycling. Visit your Indian dealer today! See the whole new Indian Line — JUNIOR SCOUT, SPORT SCOUT, DE LUXE 4, and CHIEF. Find out how easy itis to own any of these splendid machines on easy payments—and how you can get a fine RIDER'S HELMET and INDIAN SPORT SCOUT 45 FREE! Gat this RIDER'S HELMET .and INDIAN PIN MAIL COUPON TODAY! »umuumuguDEEWERBENETEBEFUVUNRERROXÓ NEUE? woran MOTOCYCLE CO., Springfield, Mass. Please send me at once, without obligation, your illuatrated- Folder showing the new 1938 Indian Motocycles, and CERTIFE- CATE of VALUE entitling me to FREE RIDER'S HELMET and INDIAN PIN, as illustrated, when I ploce my order. Name Address.. PIN absolutely FREE the minute you place your order. INDIAN MOTOCYCLE CO., Springfield, Mass. MM2 O 16-19 years 0120-30 years C331 ycarsand up O under 16 yeara Revolutionary New Scroll Saw ofa THOUSAND SPEEDS N 1932 Delta scored an engineering triumph by introduc- LU ing the first practical High Speed, Large Capacity Scroll Saw—permitting the running of the saw at full motor speed without troublesome vibration—and opening many new fields for this useful tool. Now—Delta is happy to announce a second great step forward in Scroll Saw design—Perfected Multi- Speed Drive. Through this remarkable development you can select any speed you want from 790 to 1700 R.P.M. regulating the speed within 1 or 2 R.P.M. if you wish. You can cut any material within the range of the scroll saw with full assurance that you have the best speed for your purpose. Furthermore, scientitic design has made this improvement simple, foolproof | ard trouble free. Te you are one of the many | thousands who already own a No. 1200 Delta| Deluxe Scroil you can obtain thís wonder- ful Multi- Speed I e at very small expense. Send | for civ cular. giving ull story of this unusual en-| SEND for CIRCULAR Send for 1938 Catalog showing the complet motor-driven tools and special circuiar on new Multi-Speed Scroll Saw —and the latest Delta Project Book No. 4—packed full of new and f different things to make, with many photograchs, working drawings, Enclose 10c for Project Book. Catalog G I enclose 10¢ (star me one coby OF in ne Delta Pi ets." ceive orbwork or coin) for which please sen 3 ok No. 4 of ''Practica place me on your mailing list t: 38 De a catalog of quality motor-drive: g tools. "speci tal circular on new Multi-Speed Scrol e line of latest Delta and complete instructions. will be mailzd postpaid. DELTA MANUFACTURING COMPANY 600-634 E. VIENNA AVE. MILWAUKEE, WIS. When Answering Advertisements Please Mention February Modern Mechanix

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MAKE $25 TO $30 PER WEEK AT HOME IN YOUR SPARE TIME THE IDEAL LAWNMOWER SHARPENER ike magic, the Ideal Lawnmower Sharpener makes old, dull. half DS out mowers cut like new. Simply set the mower in the Ideal and ihe machine does the rest. Sharpens any lawnmower to a perfect edge in 15 to 20 minutes and you make $3.00 to $1.50, Attach to light socket. Start In your basement or garage. Work in spare time. Attachments furnished for grinding Skates, OCA shears, hedge shears, Bickles, scythes, axes, etc. FREE CATALOG tells complete story. WHAT THESE MEN DID .. You Can Do ost men sharpen lawnmowers "Have made $1000.00 ve sharpened over M. Larsen writes: live in a town of Remember, no experience is necessary. M in spare time only. . V. Gebhardt w the past 6 months." George Seitel w 500 mowers and every customer is well p «I average 9 mowers a day.” ESY F. Stier 500 and to-date have sharpened 200 mowers at 51.25. Edward A. Mynderse writes: “Have sharpened around 500 mowers this season.” Nick Baltes says: ‘‘Last summer a sharpened 200 mowers at $1.00 each. Bucher Battery Co. write: “We sharpened over 600 mowers last year at $1.50 each. FREE BOOK Shows how! Right now, before you forget it, send for a TRA of our FREE HOOK, *'How To Make $25 lo $30 per week in SPARE TIME.” SEND POST CARD TO THE FATE—ROOT—HEATH Co. Box 328, Plymouth, Ohio For several years, Diese! engines have been replacing | steam and gasoline engines in power plants, motor trucks B and busses, locomotives, ships, tractors, dredges, pumps, | etc. And now the first Diesel-powered passenger ear is on = the market. Our home-study course offers you a real op- | portunity to prepare for a worth-whlle position In this į new field. Write TODAY for full information. No obligation. ¡American School, Dpt. D-228, Drexel at 58th, Chicago ANY PHOTO ENLARGED Size 8x 10 Inches or smaller if de- sired. Same price for full length or e bust form, groups, landscapes, pet animals, etc., or enlargements of any part of group picture. Safe return o; original photo guaranteed. 3for$1.00 SEND NO MONEY 205 man photo es snapshot (anyaize end within a week you will receive your beautiful enlargement, guaranteed fadeless. Pay postman 47c plus ostage — or gend 49c with order and we pay postage. Big XN6x20-inch enlargement sent C. O. D. HA plus postage or eend 30c and we postage. Take advantage of this amaz- Ing offer now. Send your photos today. Specify size wanted. STANDARD ART STUDIOS, 104 S. Jefferson St., Dep, 378-6, Chicago Uncle Sam — Model Maker [Continued from page 128] The map-maker first traces, on a sheet of cardboard, the two outside contour lines, those representing the lowest level of the region. With an electric cutting machine such as used for cutting jig-saw puzzles, he cuts the cardboard along the outside contour line. 'Then a second piece of material is traced with the second and third contour lines, and the cutside (second) line cut. The smaller cardboard layer is then glued to the larger, its edges matching the uncut con- tour line traced on the lower piece. This is repeated until the map is roughed in and consists of a series of cardboard layers whose edges form steps, At this point a fair idea of the surface of the area being mapped can be obtained by looking at the model. The terrain looks, however, like an area covered entirely with terraces. So a sculptor goes to work, and fills each tiny step with clay, moulding it carefully to conform as nearly as possible to the original contour of the ground. The application of moist clay does not change the shape of the map, for glue that does not expand or shrink, and is not otherwise affected by moisture, is used in assembling the cardboard layers. The map now resembles a pasteboard cake with clay icing. Plaster of Paris, is then poured over it, to make a negative cast of form. From this negative a number of durable positive casts can be made. These consist of a combination of plaster, plastic wood and celluloid. To give the model a hard surface, so that the fingernails of curious spectators, and other abuse will not mar it, the whole model is sprayed with a celluloid coating. Over this is applied whatever paint or other materials may be necessary. Various means are employed to make the maps look realistic, or to bring out certain important features. Thus, over forest areas, ground cork, stained green, is applied, 1o simulate the appearance of the actual region. Copper Ware For Craftsmen [Continued from page 93] a %-inch iron bar. The saucers are made from 18 gauge copper, 234-inches in diameter, and raised as shown. he cups are of 34-inch (outside diameter) copper tub- ing, 114-inch long. Hammer them on the outside, then place one end over the horn of the anvil, or a solid round bar, and flare the ends out slightly. Drill holes, and rivet the column to the base. Solder the cups in place in the saucers and to complete the pieces, polish and lacquer. 'The attractive ash receivers were designed with the idea of keeping the misused bridge table cover free from cigarette ashes. Once clamped to the edge of the bridge table, they will stay put. A set of four of these pieces is a worth-while project for any craftsman. The bowl is a 3-inch disk of 16 gauge soft sheet copper, cupped or raised to a depth of about Z$-inch, with the top rolled in slightly. Hammering is done with a ball pein hammer. The copper will have to be annealed about three times in order to raise the bowl to the required depth with- out hammering the metal so hard that it will crack through, The clamp is cut from the same material and hammered hard to make it springy. The cigarette rest is formed aud the piece bent into shape. Drill holes and rivet to the bowl with a number 14 brass escutcheon pin. The pin allows the clamp to swing up along the side of the bowl so that the ash receiver may be set down on the desk or table if desired. The trays may be finished in polished copper or they mav be coated with a nitrate of copper solution and burned black, burnished with fine emery paper, and polished with nm wax. Lighted cigarettes will not affect the latter nish. Metal stand picture frames are very popular, and they too are very easily made. The frame illustrated is made from 18 gauge soft sheet copper to accomodate a 5 by 7 inch picture. Cut out the base piece and hammer on one side with a planishing hammer, then roll the two ends under. around a 34-inch bar. The upright is cut out, and hammered in the same manner on what will be the outside. Place two hard wood blocks in the vise, and slip the bottom edge down between these up to the dotted line and bend torward sharply. Then place the side between the blocks, up to the first dotted line, and bend forward. Place a piece of flat steel 14-inch thick tightly against the bent up side, and clamp in the vise and bend the piece forward to form the guide for the glass. Bend the other Short side forward and the round disk up on the dotted lines. These operations are photographically illustrated. Holes may be drilled and the upright riveted to the base, or the pieces may be soldered together. 130 Accepi No Substitutes! Always Insist en the Advertised Brand!

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.. Now in . my OWN Business. s Would you, too, like to own a business where you could take in $200 your first week as did L. A. Eagles in Madison, Wisconsin? We want a reputable, honest man in each county. This man need not have any special experience or more than ordinary ability, but he must be honest and courteous. Such a man we will start in business for himself. You can make far above average profits in the rug-cleaning business—a high-grade business all your own. Many earn $125 to $200 per week—some considerably more, NO SHOP NECESSARY The rug-washer finishes rugs like new on the customer’s floor. Anyone can run it. Electricity does the work. A quick, thorough and highly-efficient method that restores the natural beauty of floor coverings. "There are hundreds of customers—in your vicinity and nearby towns. The business grows steadily, Simply clean a few rugs or carpets. These customers tell others and also give you their future work. Soon you will have a prosperous year-around business. Send coupon for booke let explaining everything. "Profits Pay for Home" Harry Hill built and paid for a home from rug-washer profits, His first day's business was $86, A. L. Miller says, ‘Have had rug-washer 6 years—have earned as high as $92 a day.'' M. O. Malmin earned 3 times the cost of hls machine the first two months. Another letter says, "Made $70 in 13 hours.'' You, too, can enjoy a large income. Ones, Rooke! MAIL COUPON NOW 1 VON SCHRADER MFG. CO. 1 202 PL, Racine, Wis. 3 Send at once (no obligation) your free booklet illustrating j | rug-washer and telling how I can own my own permanent 4 business; how I can earn large profits at prices below other methods; how I can become f nancially independent In a short jy time; and how I can pay on easy terms. “Never a Complaint" C. J. White says: “$100 business in six days—never a complaint." That is the nicest part of this business—every customer is more than satisfed. Stains and blotches disap- pear and vivid colorings and freshness in faded floor coverings come back. ^" EVERY MACHINE GUARANTEED You take no risk. These machines have been manufactured since 1018 and are used by the United States Gorernment and by many of the world’s largest hotels. They are fully GUARAN- TEED. EASY TERMS The complete equipment is inexpensive, A rede // sonable down paymeut brings every AS thing to you and the balance is E Y paid monthly. From the start, (Q k N) you have your own business— N- one that is profitable and of R which you can be proud, (© VON SCHRADER MFG. CO., 202 PL.. RACINE with your CK Ki-Yak—if you hurry! Welghs only 20 Ibs— Carry on Bike or by Hand BOYSI MENI See how easily thia MEIN old youngster carríee hia MEAD CK- ELYRE! What fun you' ave with one—. — you can assemble it YOURSELF at home in oniy 4 evenings from our numbered, cut-to-fit Construction Kit—and SAVE HALF the factory- built cost. , No experience needed. Thousands in use, Tell DAD about this inezpensive educational project —and the FUN it, will bring you during VACATION! Rush Toe N for Cireulara showin eautifu Sirs photos of Mond Ki-Yaks —salling, paddling. and with motor Low intro uctory actory-To-Iot Prices, $6 GIFT PADDLE OFFER. MEAD GLIDERS Weighs oniy 50 lbs. 15 S. MARKET Igbe ony motor Dept M-28, 414 hp. or le, CHICAGO oars and AUTOPOWER tells you how in plain, easy, simple and illustrated instructiong that anvone can follow. Change auto generators into useful, practical A C and DC generators and motors with voltage from 2 to 1,000 volts, for power, light, welding, Generat ROD. PLANTS. Send for dorsed-by thousands. S. W. DUNCAN, Publisher When Answering Advertisements Please Mention February Modern Mechaniz radio, sound, ete. s can be driven b: t T R BUILDING AN A C WELDER THAT ACTUALLY WORKS UP TO A 3/16 ALSO COMPLETE PLANS ND No previous experience nor snectal tools needed. v wind. water, fan helt. ete. INSTRUCTIONS FOR WATER POWER used and en- TOR WIND vour copy of “AUTOPOWER.” v $1.00 postpaid. ^ Already 412 S. Hoyne Ave., Chicago

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[They Need MORE PICTURES! |

HOW TO |! WITH YOUR CAMERA! Pictures| Pictures! Maga- zine and newspaper readers demand MORE! Editors are clamoring for them! Dozens of NEW picture magazines—and thousands of other magazines, newspapers, trade papers—are paying HARD CASH for them! How can YOU cash in on this de- mand? Use YOUR OWN CAMERA. You don't have to know how to take smart “angle” shots, "arty" views, or technically beautiful photographs! What editors are BUYING are pictures with news value, popular appeal, HUMAN INTEREST! Pictures you can take in your own back yard, cn your own street, in your own home town. Learn WHAT to photozraph, HOW to photograph it, WHERE tc SELL it, and you ean *'eash in’! FREE BOOK This FREE BOOK tells how you can learn to take the kinds of pictures that sell—and all about the horne-tra:ning course that has en-

3 Checks In 1 Week! York McClary, of Belvidere, Q., writes: ‘Have received 3 checks this week. Qwe you a lot fof starting me on I this path.” Made $237.50 While Still Learning ''Have added up how much I have taken in since I sold my first pic- ture, I have made $237.50!"

ivi i abled hundreds of amateurs to turn their Olive Hastings, hobby into a profitable business. And you can Dorchester, Mass, pay for the course in smal} monthly payments!

Get YOUR share of the money being paid every month for photographs. The world is go- $50 For His ing PICTURE-C Very First dust lock over ae Work! magazines cn EL per

newsstands YOUR SELF! Find out NOW how to make money

B Well-known mage azine paid L. D.

with YOUR , camera. Eldridge, of St. d for FREE TERR Pa ul, a inn., BOOK m Today NE bad, E et Money | $50.00 Or very a m SR CAMERE frst work sub- | GRAPHERS. Ing. gy ee mitted, S3rd St. N. Y. City. 2 See <a eme E " j 1 [ UNIVERSAL PHOTOGRAPHERS, Inc., * I | Dent. 332, t0 West 33rd Street, New York City i Please send me your FREE BOOK, “How To Make Money With Your Camera,” which explains i your home study course, No salesman will call on me. i - i Dame LLL desse — E T E I I E 1 Í scares aae rus vena nm TT I 1 e [| Clty cesceae afar aye eise ead NOXAE ERS bre area jaar’ ae Gtalercccsecceese LI Accept No Substitutes!

How Camera Shutters Work [Continued from page 113] wide slot is used. The focal-plane shutter thus exposes a single point on the film, not the entire film, for the time of exposure for which the shutter is set. In addition to the different slots producing different speeds, it is possible to increase the tension on the spring actuating the take-up roller at the bottom of the camera. This will cause the curtain to wind up faster and the same slots to move more rapidly, producing faster shutter speeds since the film will be exposed for a shorter time. The shutters on the Graflex cameras have four small slots and six tensions, producing a combination of twenty-four shutter speeds. <A fifth slot, as large as the back of the camera, is used for time ex- posures. Another type of focal-plane shutter, such as is used on the National Graflex cameras, consists of two curtains so designed that with one spring tension, different speeds are produced by varying the opening between the two curtains. Most of the focal-plane shutters are made of special cloth, although a few miniature cameras have a metal shutter. Focalplane shutters are capable of producing speeds as high as 1/1000 of a second and slightly higher in a few in- stances. The íocal-plane shutter, situated at the back of the camera near the film, is entirely independent of the lens and, as a matter of fact, permits lenses to be interchanged when the camera is loaded with film. With this type of shutter the container for the lens cells can be smaller. It is called a lens barrel and usually, although not always, con- tains the iris diaphragm leaves, hence the term “in barrel with iris diapkragm." Since the opening in the focal-plane shutter passes just in front of the film, light from the entire lens can reach the film during the total duration of the exposure. Because of the masking of part of the lens by the leaves of the between-the-lens shutter during a portion of the exposure, tests indicate that a focal plane shutter, when set to the same high speed, allows approximately one-third more light to reach the film. This is the basis of the claim of the one-third added efficiency of the focal-plane shutter. This added efficiency is quite necessary in speed photography when the diaphragm leaves should be closed as much as possible to increase the depth of field, and is also of importance in making any photograph when light is poor and but a very little more exposure will make a printable negative and thus save the day. At the present time, although the focal-plane shutters of the smaller cameras can be equipped with an accessory for flash synchronization, the focal-plane shutters of the larger camera cannot be synchronized with flash lamps. It is for this reason that press and commercial photcg- raphers, in selecting a camera with a focal-plane shutter, so necessary for speed photography, also equip it with a between-the-lens shutter. This shutter additionally pro- vides instantaneous speeds as slow as one full second. In the past, the Compur shutters without self-timer have been more satisfactorily synchronized with flash lamps. How- ever, these accessories are now being sufficiently adiusted so that synchronization will be satisfactory in either in- stance.

Flying The Subway Express [Continued from page 41] that beckoning curve, thunders, another train like the one we ride, and behind us comes another, all on the same track, racing in the same direction, carrying possibly 1,000 pas- sengers each—small cities going to work or going home at nearly mile-a-minute speed. During the rush periods as many as 32 trains like the one we ride will slide into a station, take on and discharge passengers, and roar away again, in a single hour—less than two minutes per train. In round terms, this means that a transportation population roughly equal to that of such cities as Elgin, Illinois; or Elkhart, Indiana; or Baton Rouge, Louisiana; or Ann Arbor, Michigan; or Riverside, California; is routed over a single subway track in one hour. Small wonder that subway schedules are far more strict than those of a transcontinental train. This tunnel through which we rush is not a dull, dark hole that concrete walls kut a sentient thing which speaks in crashing echoes, talks to the motorman in a language of blinking lights, warns him cf danger ahead, reaches out to trip his brakes if he ignores the signals. We zoom into a curve and the speed of the train slackens. 'The motorman, who knows every inch of his run as we know our backyards, takes the curve at its critical speed limit. It is a dangerous curve, threatening derailment or a pileup into [Continued on page 134]

Always Insist on the Advertised Brand!

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John made'42** in one day in his NEW e Bu . ee @ Get into this business NOW—a business which is so new that it is practically without competition. This alone should enable you to make realy BIG MONEY. Hotels, homes, clubs, coun- try estates offer tremendous possibilities. Our new DETER- GER washes upholstered furniture, tapestries, all sorts of fobrics, electrically right in your customer's home, with a new soapless soap whipped into DRY suds. No liquid touches the fabric, therefor the furniture is ready for use soon after cleaning. We have helped hundreds of men get into business for them- selves with our automatic equipment. The U. S. Government and many of the world’s largest hotels use our machines. Make Money the FIRST DAY You are ready to go to work the minute you get the outfit, so you ought to be taking in big profits the first day. We want an honest, ambitious man in every locality. If you are that man we will help you get started for yourself in a business with tremendous possibilities, You don’t have to rent a No Rent to Pay shop. You don't have to hire a building, for you do the work right in your customer's home. You save the expense of carting furniture back and forth to & central plant; the owner's home is your workshop. J. S. Corson says "I cleaned seven living room sets and fourteen chairs, as well as twenty-five automobile interiors the very first month and made $279.50.” Berger Hanson wrote’ My investment in your DETERGER was the wisest I have ever made. It is my most valued asset.” Barrett says: "Made $28.00 in eight hours, on another job made $11.00 á in two and one-half hours.” Alex Gulkin's business ex- panded so fast that he al- ready hassix DETERGERS making money for bim, PayasyouEarn Only a limited amount of moncy is needed for a down payment. The balance you send on easy terms. Most men find it possible to make far more than the cost of the machine before the payments come No liquid touches the fabrice when cleaning with the DETERGER. c due. Every machine is fully GUARAN- TEED and satisfied customers send their friends to you. Book sent FREE Write today for copy of our booklet “Get Into Business l'or Yourself." Let us tell you how easy it is to get started in a year around business where you are your own Boss and can stop Worry- ing about just a job. Write today —NOW, VON SCHRADER MFG. CO.D-202 PI; Racine, Wis. VON SCHRADER MFG. CO. D-202 PI., Racine, Wis. Send me (without obligation) your free booklet telling me how I can own my own business and become financially indepen- dent and how I can pay for the DETERGER on easy terms. Dr ——— as « The Plastex Industry needs manufacturers on small scale and for big production of Art Goods, Novelties, Souvenirs, etc., in Plastex and Marble Imitation. Experience unnecessary. Equipment and simple instructions furnished for specd production. Small invest- ment brings big returns. Nation-wide demand for these low priced goods. Ambitious men have chance for real prosperity. Our free book will interest and bencfit you. Big wholesale season now starting. PLASTEX INDUSTRIES, Dept. 3. 1085 Washington Ave., New York, N. Y. WITH LENS IPHOTO ENLARGER "25 APERFECT ENLARGER AT 9 95 B |A PRICE YOU CAN AFFORD j The FEDERAL Enlarger has all the superior features j found only in the most expensive enlargers. k Tall Ventilated Lamphouse uses 200 or 125 watt amp. * Book-Type negative holder enfarges all size film, plates up to 195g” by 21/2”, and holds negatives up to 4" by S". * Spiral type Micrometer Focussing adjustment with lock. * Built-in Disc Diaphragm and Red Screen Filter, * Interchangeable Lens Mount. *^ Fully corrected Achromatic F.8 Lens with 31/2" focal length. * Can be used for Contact Printing. * Designed to project Horizontally, largements or positive transparencies, a Made In + Sturdy lasting All Metal construction. v. *" * Hardwood Baseboard takes enlargements up to 12" by 14". extreme en- This is Truly an Qutstanding Value, com- are this enlarger with others selling at any “price and you will see it ls equal to the est, ORDER NOW at only $9.95 complete with Lens, West of the Rockies $10.75 Tostpald; C.O.D. 1f preferred, plus postage. Candid Camera Supply Co. Dept. W.F. 303 W. 42 St. New York, N.Y. When Answering Advertisements Please Mention February Modern Mechanix A REAL GAS ENGINE FOR ONLY 587 YES! Yes! A real gasoline engine that will provide thou- sands of hours of pleasure and instruction!! Just think of what you can do with one of these engines!| Fly a plane—install in a boat—power small tools—thousands of uses in work and play throughout the yearll ONE DAY _ DELIVERY 4 Port 2 Stroke Cycle— %” Stroke— i$" Bore— 300-12,000 R.P.M.— Weight, 12 oz, (Motor)— Turns 14” Prop. 8" Piteh— Bearing Surface, 35 "X1 "= Crankshaft, fs” Diam.— b Thousands cit use y enthusiastic cus- Rotation, Either Direction tomers! Lowest-priced gas engine in the world! Backed by the famous G.H.Q. Guarantee! An engineering triumph accom- plished after years of research. FINISHED PARTS KIT $8.50 No Machining! Quickly Assembled! FINISHED ASSEMBLED MOTOR treo flywheel $12.50 . G.H.0. MODEL AIRPLANE CO. - ET York, N. Y. POST PAID _ 854A East 149 St. 133

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NOW...vov can LEARN TO DRAW AT HOME ART BRINGS BOTH PLEASURE * +*+ ox* * Tf you would like to acquire the ability to become an Artist, you your own SPARE TIME. Study- ing Art at home is actually fun. can gain this practical way should equip you to earn good money Own"—and be your “own boss." @ DESIGNING e CARTOONING Maybe you have never studied Art before— is not too late to start now. Washington School Our in- tensive course of training Our plan is fascinating, pleasant, and can be made TWO ARTISTS’ OUTFITS Upon enrollment you will receive the Use Coupon Now! Tt brings you the details by return mail, Aus NAE "e can learn to draw AT HOME in The new knowledge and skill you Later you can start out * ‘on your All in ONE Practical Course perhaps you have always wanted to—if so, it dD of Art has been established 24 vears. i i ining includes all the important branches of Commercial Art. ating, sant, profitable. We invite you to write for full details. included in the W. S. A. Course first Commercial Artist's Outfit which includes everything needed to start the course. on, a niore advanced set UN of Art materials will be furnished, ^ iX / 1h ` WASHINGTON SCHOOL OF ART Studio 202E, 1115—15th Street, N. W. Washington, D. ©. I am interested in learning to draw, Please mail FREE ?opy of your Book, “Art for Pleasure and Profit.” Name .........-... e eene ^ Occupation.. 134 Landing Fish Through Ice [Continued from page 90] who capture them in the fall and keep them in running water for selling. One finds little difficulty in keeping minnows alive in cold weather, even without frequently changing the water. If you must find your own, look near mouths or streams where they enter a lake and in open water at its outlet, or else cut a good-sized hole in the ice covered stream and let down a net baited with cracker crumbs or soap shavings. Fishing holes must be at least 16 inches in diameter at their tops and enlarged and smoothed at the bottom to avoid chafing the lines. Cutting a long gash in the ice, then gradually enlarging its center, is a good method. Holes should be located 75 feet apart; fifteen * "tip-ups" is the limit one man can tend, but the law will likely limit you to less. While an ice chisel is the best tool to use for chopping, a hatchet will suffice for up to 10-inch thickn For heavier ice, a crowbar or a real stout ice chisel, made from a heavy carpenter’s chisel Jet into a 6-foot length of iron pipe, and an axe will be required. These tools, along with a good-sized minnow pail, a screen mesh dipper to clear slush off holes and dip minnows, and fishing tackle, are all the equipment required. A small toboggan makes an easy way to tote gear along with food and drink, if you can- not drive too near the fishing-grounds. A single correctly located hole will catch more fish than a dozen poor ones. To really catch fish, prospective fisher- men should know something about their habits in order to cut holes over likely spots. Luck is usually better on mild days, and through thin ice rather than thick. Try fishing where fish were known to have been caught in the fall pre- ceding spring. In general, perch and crappies favor weedy shallows with sand bottom; bullheads stick close to mud reefs and overhanging banks and wall- -eyes and pickerel cruise about in deeper channels, preferably about submerged weed beds and sunken rock piles, If you can locate an open patch amidst weed beds, cut a hole over it and rig a "'tip- The size of hooks used should fit the bait as well as the fish sought after. Use No. 1 hooks for yellow perch and No. 2-0, up to even 4-0, for pike and pickerel, with or without leaders of bronzed wire or twisted gut. Twenty- five feet of line should be enough for each "tip-up" over water averaging 10 feet in depth. Use a stout grade, around 18-pound test, preferably braided, as a twisted, kinked line snaps easily when frozen. The minnow should be hooked directly behind its top or dorsal fin, and a light sinker used to keep it from loafing up under the ice. The ideal setup would be to keep the minnow a íoot above bottom, but with the line shortened so as to just prevent it from reaching the weeds. Flying The Subway Express [Continued from page 132] a concrete wall if taken too fast, so human judgment is not relied upon. If the motorman enters the curve at too high speed, a steel foot rises and clamps on his brakes. We flash past a series of metal flags projecting from the tunnel wall outside the motorman's window. They bear the cryptic marks ''R-6," *R.8," and "R-10." The conirel handle is shoved up and the train gathers speed again. "R" means “resume speed," the motorman “explains. When the flags appear, it is safe to push the iron horse to top speed again. The figures 6, 8, and 10 refer to the number of cars in the train. Engineers with charts and slide rules have taken such imponderables as mess and momentum and gradients and calculated to the inch the points at which it is safe for a ten- or eight-car train te pick up speed. Every eight or ten blocks a brightly ligbted platform crowded with people flashes past, but we do not stop, for we're on the inner track flying the subway express. Three yellow lights, one on top of the other, flash into view. "Curve ahead," says the motorman, jerking his head toward the signal. Green flashes on in the signal box just ahead—all clear in the block we are approaching. Red——and we stop until a train we do not see pulls out of the block. Yellow, and we proceed with caution. These are obvious signs which any motorist who obeys a traffic light understands. But what are these mysterious “S. B." markers which swing .into view now and then and are left behind? They must be important, for they are illuminated by a powerful white light, but although our motorman watches them sharply he doesn't seem to do anything about them. You prompt him with a question and he shouts above the din: “Section breaks.” [Continued on page 140] Accept No Substitutes! Always Insist on the Advertised Brand!

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U. S. MANUFACTURERS desire men to learn Electric Arc Welding and get prac- tical experience under actual production conditions in the laboratories of the School of Engineering. Moderate training fee. Accepted appli- cants will be fully trained E. ae ; ~ uo F. "AIC Welding until ready to pass rigid test and assisted in securing em- modern Industry : ployment. presents one of the outstanding opportunities for steady income and future success. Welding is growing rapidly, i ; 4 .. replacing large and intricate castings, rivets, nuts, bclts, screws. It is commonly used in assembling cranes, hoists, bridges, structural steel work, etc. No limit to the appli- cation of welding to industry, increasing durability and reducing manufacturing costs. MU ie usc ones um tt tss us vens a ny UNE ums uam ns Rmi re ind a wr There is a decided shortage of properly trained Welding Operators. + 1 P Technicians and Welding Engineers. Why be content with ordinary work, a send: Free Booklet ‘‘The Dawn of A Gigantic Industry and its hit and miss jobs and low pay when in a short time you can become a utstanding Opportunity." Also tell me how I can become an trained Specialist in Welding? Are Welding Operator in 3 months... Welding Engineer (1 year).... Gas Welding Operator (6 weeks) ... Welding "ee MILWAUKEE mar Lun Ces AE dena Basie is 6 CHenL of ENGINEERING, | — Sustitute of Electrotechnics If interested in other courses, check here. Refrigeration and Air Conditioning Technician ) Radio and Tele- 5 E qommerclik Badio Engi, * x r gineer . 85. egr 238-M M N. Broadway and E. State Milwaukee, Wis. r gree ( EARN UP TO $75 WEEKLY RADIO SERVICE. Let R. T. A. Train You At Home Write quick for this Free Book that tells you why R. T. ÀA.s Practical Homs Prepare Yourself at Lincoln for a B e TRAINED PILOTS * anc MECHANICS Training Course offers the utmost. in i i 5 irli ts earn TRAINING including Television. Talking Pictures Pay dob in Ar MQUNERIEE- UR. to ane ene > T iustrations, including $200 a month, Government Approved Flight Training pre our sensational Service Equipment Offer that heips pares you for any Pilot’s License including Commercial you earn money almost at once. Radio progress Transport). Mechanics Truining prepares you for Mechanics License. is astounding ‘the world. Heed the call of RADIO! n A TRAINING BLAUE. 12 laboratories and shops. We RADIO TRAINING ASS'N. OF AMERICA assist graduates in locating positions, Write n LINCOLN AIR- Dept. MM-28, 4525 Ravenswood Ave., Chicago, III. PLANE & FLYING SCHOOL, 400-H Aircraft Bldg., Lincoln, Nebr. SEND FOR YOUR 80-PAGE CATALOG 100 PAGES—NO. 10—MAKE BEAUTIFUL FURNITURE at a fraction of store cost. 14 pages of lumber with prices. Veneers and plywoods of all woods cut in usable sizes without waste. USE THE CRAFTSMAN new process of inlaying, using our new process ART INLAY GLUE, needing no clamps for the finest work. Hard-to-find rare gralns for all woods, including forelgn —special hard-to-find hardware, mouldings, turned legs, ete. Lists and illustrates 76 blueprints of scroll pat. terns, inlay table tops—Kits for !nlaid art boxes. plaques, trays, book ends, ete., that anyone oo make 22 pages in color. VENETIAN BLINDS for one-third of usual price. All material requiring only a saw, screw driver, à tack hammer and paint to assemble. HIC co c A MAN WOOD SERVICE CO. 2731 MARY STREET Order f RAFT c When Answering Advertisements Please Mention February Modern Mechanix 135

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THERE ARE TIRE PUNE. TURED) 1001 Repairs In Home, Auto, Farm For Only New plastinoid “putty” — SO-LO— fills cracks, holes in tires, shoes, boots—any- thing of rubber, leather or Cloth. Spreads on like butter. Dries tough. Waterproof, flex- AIRPLANE AND on MODEL KITS — repairs) shows many uses. At any 10c or hard- ware store. EACH a+. To fit the Skill of EE EE T every Builder! QUAKER FLASH Outstanding among all G7 gas-powered models. * Uses any model airplane motor. Large, but folds to carry in car. 314 in. rubber wheels. Wing» span 67 in. Length 47 in. STINSON RELIANT ISR7A 3X4 in. Scale Model. . . . The highest development in seale model building ever offered. Complete in detail even to seats and hinged cabin doors. 31 in. wingspan. $4.95 plus 30c Postage r low cost deliveries, investigata thia new pum Ed Swift, safe, comfortable, amazingly economi- call Lees "th hen 1-8c a mile operating cost. Cheaper à than shoe leather! Eaey to park, Ideal for getting te S Work, school, making deliveries, pleasure spine, ete, deal i FREE BOOK! Sesso deeler or write DEALERS. Write quick for Speclal Offert THE CUSHMAN MOTOR WORKS, Dept. l-2, Lincoln, Nebr, $125 and up 1.0.5. Factory d $3.25 Go plus 20c | Postage "1938 CATALOG FREE à Quality Radio—Save up to 50% FREE HOME TRIAD. AVONET: BACK if not satisfied. ONE R GUARANTEE. 6i MISS STRATOSPHERE| beautiful models. H to iE tubes: AUTOMATIC yj ANDE d Exact 14 in. scale model kit tuning modela. Radios that get EUROPE. d la ce — Chamberlain's | T New battery radios for farms, Auto radios, ot. C Te. shia inueduc FREE HOME Send Vosteard for FREE catalog— ae „Send ORLD-WIDE RADIO Co. high al: ing a new type of construc- Order Now.Sen 2670 ELSTON AVE., DEPT. M-2, CHICAGO a f $1 Dep. Pay balance C .O. tion using wocd veneer. ARROW SPORT V3 | | 60 POWER TELESCOPE $2.19 Authentic detail model of an outstanding Ford V-8 pow- VARIABLE EYEPIECE. 20X--40X—60X ł A 4 i I : ered sport plane. 30 in. wing- NEW! Three telescopes in one. 3 different mag a span flier. images with 40 end 60 power (or extra long piana \ range. Guaranteed to bring distant Á c d objecta, people, sports eventa, ships, moon, etara, etc, 60 times aa close, Most powers T fl made for anywhere ar the money. Can be collapsed to less t than a foot in length. Multiple lens system. 30 mm. objective, in heavy brasa.mount. Directions., Included Tor using as a compound 4 lens microscope. American made. e pay the postage. Only $2.19. Catatog of Microscopes, Binoculars, ane E on request. BROWNSCOPE CO., Dept. 72, S W. 27th St. «a New York, N. Y. BDC pius 10e postage Al Williams’ GULFHAWK Easy-to-build model kit of famous Grumman, duplicate ing latest navy fighting plane, plus new features by Major 50¢ plus 20c postage Williams, pA SHIP MODELS ed SIGNS SHOW E In addition to scores of airplane models, the CARDS Psy new 52-page Megow catalog illustrates many fascinating BOAT MODELS, comprising almost AND ALL ro every type from ancient galleons to the modern | N aen FREEHAND TESTENIN QUEEN MARY. Also supplies and parts. 1 rite Dept. TTERING Send 5c postage for your copy! REGINA gehoor OF NETTI hil e Philadelphia, Pa. or—217 N. Desplaines St., Chicago, Il. Please send me: í QUAKER, FLASH f ] ARROW SPORT V-8 EARN EXTRA MONEY. _ MOUNT BIRDS G- ANIMALS FOR PLEASURE GEROFIL Send Today for FREE BOOK chock full of items and fully illustrated show STINSON RELIANT SR7. T WEK MISS STRATOSPHERE ^ NEW CATALOG Money Order for 2... .... Semanan - y is enclosed. a complete Line of GLASS EYES—EFUR- ` ~~~ RIERS and TAXIDERMISTS SUPPLIES, LEARN TAXIDERMY THE SCHOEPFER^ METHOD 'omplete course, best method known— mé EASY—S ,E. Get into this rapidly growing business. Write today. Send 50c and pay postman balance on arrival. Price $f. G. SCHOEPFER, 134 West 32nd St. (Dept. M-2) New York City cor 136 Accept No Substitutes!’ Always Insist on the Advertised Brand!

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AUDELS Carpenters and Builders Guides A 377454 vols.56 insido Trade. information for Carpenters, Builders, Join- erg, Building Mechanica and all Woodworkers. These Guides give you the short-cut instructions that you want— including new methods, ideas, solutions, plans, systems and money aaving suggestions, Án easy progresalve course for tha apprentice and student, Baerlon daily helper and uick Reference for the mester worker. Carpenters everye where are using Lhese Guides aa & Helping Hend to Easier Work, Better Work and Bete ter Pay. To get this assiste fo end mil the FREE COUS and meil . Inside Trade Information On: PON below, : How to use the steel equare—How to file and set Gaws—How to build furniture—How. to use & mitre box—How to use the chalk line—How to use rules and scales—How to make joints—Carpentera Brithmetic—Solving mensuration problems—Es- timating strength of timbers—How to set girders and sills—How to frame houses and roofs—How to estimate costs—How to build houses, barns, gar- eges, bungalows, ete.—How to read end draw plans—Drawing up specifications—How te ex- €avate—How to use settings 12, 13 and 17 on the eteel square—How to build hoists and ecaffolds— ekylights—How to build stairs—How to put on interior trim—How to hang doors—How to lath— lay foors—How to paint EEBNREEABERUEENERRZEEREREEEENEERESESERENENNEENNEESEEREEEERREENAR THEO. AUDEL & CO.; 49 W. 23rd St., New York City Mail Audels Carpenters and Bullders Guides, 4 vols.. on 7 daya’ free tria], If O.K* T will remit $1 in 7 days, nnd $1 monthly until $6 js paid. Otherwiso I will return them« Nz obligation unless I am satisfied, 77 AAATESO....usueeaenevavecosoaspeccsosossonosassesouroessososososousegene sesse Occupations: va ases YESSIR 4.ron IOt tt Reference... Learn Publie Speaking At home—in spare time. Many overcome stage-fright,’’ gain self-confidence, and increase their earning Power, through ability to eway others effective speech. Write for free bo: A Work Wonders With Words and requirements, ^ NORTH AMERICAN INSTITUTE, Dept. 2052 3601 Michigan Avenue Chicago, Illinois INVENTO RS PATENT YOUR IDEAS SEND FOR FREE BOOK =m HOW TO OBTAIN A PATENT Written by a Former Member of the Examin- ing Corps (1922-24) of the U. S. Patent Office. If you want to profit by your idea, you should = take steps to apply for a U. S. Patent at once, Your first step is to get this Free Book. This interesting illustrated book contains valuable information you should have. It tells you fully how to obtain a patent on your idea in the quickest way. With this Free Book you will also receive a “Record of Invention’? form on which you can easily record your idea. Personal and Confidential Service: Your case will be personally handled only by a Registered Patent Attornev who is also a Former Member of the Examining Corps of the U. S. Patent Office, All com- munications confidential. MAIL COUPON TODAY for FREE PATENT BOOK end RECORD OF INVENTION Form —. CARE MILLER | REGISTERED PATENT ATTORNEY "FORMER MEMBER EXAMINING CORPS U.S. PATENT OFFICE B Woolworth Bidg., 35th Floor, Dept. 28B, New York City MILLER BUILDING, Dept. 28B, WASHINGTON, D. C. Please send pe ur Free Book, ‘How to Obtain a Patent," and a your “Record of Invention’ form. -AND TREET YoursELF TO A PACK OF yp PERFECT SHAVES! NAMB e ——— E i f R GEM AND EVER-READY RAZORS ADDRESS ...eserscasaosesosacoonovesesssoecsoeopsessaseo Treet Safety Razor Corporation, Newark, New Jersey LAT mmm m Uam SRS NO UD UD UD ND GN UD UD FJ ND UD UD C GG UD UE UD OM JW When Answering Advertisements Please Mention February Modern Mechonix 137

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mington NOISELESS PORTABLE Now you can owna brand new, latest mode! Remington de luxe Noiseless Portable for only 10¢ a day. This amazing typewriter has all the mod- ern features of the big office ma- chines. Standard keyboard, handset tabulator, composition keys, autos. matic ribbon reverse, two color tibbon shift, etc., PLUS the NOISE. LESS ACTION that types ina hushed whisper! ENJOY 10 FULL DAYS TRIAL...FREE Try this great new Remington in your own, home for 10 days. Use it as much as you like. See how convenient it is to type letters, memos, reports; how much pleasure you get from putting your spare time to profitable use. Earn extra money—develop your ideas—enter contests. You can write better—think better—~spell better when you use your Reming- ton. If you're not 100% delighted, return it AT OUR EX- PENSE at the end of ten days, We pay transportation charges BOTH WAYS. ` EXTRA! HERE'S WHAT HURRY! RUSH COUPON FGR "FACTORY" OFFER Write for big Free illustrated catalog describing all of the fa- YOU GET mous Portable models; special F R E E ' 104 a day plan; 10-day free trial s offer, free typing course that 1.Typewtiter Course, makes ic easy for anyone to typewrite, and Double Duty Carrying Case that can be used as an overnight bag. Don’t send any money—just mail coupon and get all the facts WITHOUT OBLIGATION. Anyone can learn to typewrite with this FREE 19 pagecourse. 2. 10-DAY FREE TRIAL in your owa home.Convinceyour- ` self without risking REMINGTON RAND INC. a cent, , 485 Washington S!., Depl. 141-37, Butlalo, N, Y. REMINGTON RAND INC., Dept. 141-37 465 Washington St., Buffalo, N. Y. Rush FREE Catalog and full information about the ''10£ a day" blan, Free Trial Offer, Free typing course, etc., entirely without obligation. This ss not an order. Name; vus csiee noris saints voa VE ES enr cee Addressyeansss iune n rele S oL UU REISEN QM quom emma ta mo s en ra n o s is Ri vestes Stalb. 1. cies xs Accept No Substitutes! ARREST HIM, OFFICER! ULL HAVE COMPLETE FACTS ON THE OTHER ———— FELLOW TONIGHT! Secret Service Operator No, 98 is on the job, . . FOLLOW HIM through all the excitement of his chase af er the counterfeit gang. Write NOW for F R E Confidential Reports No. 38 Made to His Chief t It may open your eyes to the great epportunlty for YOU as a well paid Finger Print Expert. The kind of work you'd like, Excltement! Travel! Thrills! A REGULAR MONTHLY salary, REWARD MONEY. , Grad- uates of this school HEAD 47% of all Identification Bureaus in U. S.! Write for Free Reports, Finger Print Book, low prices. Easy Terms Offer, if 17 or over. E Literature will be sent only to persons stating their age. INSTITUTE OF APPLIED SCIENCE 1920 Sunnyside Ave., Dept. 2352, Chicago, Iit. IT’S NEW! MAKES! MENDS! PLASTIC! ELASTIC! FLEX-0-FIX—applied from tube as a plastic, dries tough and elastic—waterproof, acldproof, electrical resistant. MENDS: rubber, leathers fabrics, etc. (combination patch and cement MAKES: moulds, washers, packing, etc. INSU» LATES electric wires. Used by craftsmen, me. E » Booklet nd auto owners, etc. k: ea oe tubes: WRITE NOW for FREE BOOKLET showing hundreds of everyday uses. Ask for FLEX-O-FIX at har quare. au supply, sporting Eoods, varlety stores. If not available send money FAUND PRODUCTS CO. Dept. M-28 43 E. Ohio, Chicago Learn to Repair, Adjust, Oo S Test and Renew all Good pay in Auto Work now, Learn at home in spare time with Dyke’a famous training and ''Self Starter." Nothing else like it. Complete with 85 lessons comprising 1593 pages, 2300 Questions and answers and more tions, DYKE'S AUTO COURSE gares "ws Only $635 nes Self Starter Goodheart-Willcox Co., Dept. 12, 2009 Michigan Ave.,. Chicago than 4000 illustra Amazing value at Write for FREE seriptive Folder. HIGH POWERED TELESCOPE —"° ii money ^^ Marvel Long Range Telescope. Approx. 3 feet long extended. Good lenses, All 4 secs. bound in brass, Large 36 mm objective. Only $1.19 postpaid. C.O.D, 12c extra. Fine magnetic compass in chrome case included froe. ET offer go short time only. - 251 63 SPECIAL 5 Sec, telescope with powerful compound micro- Scope feature. 32 inches long open. Handsomely trimmed fn satin brass. Bright Images combined with long range. Made in U.S.A. Only $1.69 postpaid. (This telescope l3 not offered elsewhere at my price), Order now. The Hobby Man, Dept. » 703 W. State St., Jefferson, lowa Eren GET MORE REAL HELP FROM YOUR BOOKS AND COURSES, Learn the best way to plan your work and work your plane Amazing new course teaches you‘ *How to Study and Work for Best Results.'* Used by home-study studente, business and trade schoole throughout world. Full price only $1, postpaid. Or € O D, plus postage. Satiafaction or money ack, For free detalls ma‘! penny postcard. No obligation, PLYMOUTH SCHOOLS, Dept. 202, 432 Plymouth Ct., Chicage Write today! LETTERING ARTISTS MAKE Æi; MONEY BE A SUCCESS—LEARN SHOW CARD PRO- FESSION ''THE ACME STUDIO WAY''CSpend 2 full weeks our Big Chicago Studios—finish training spare time at Home. Hundreds taught this way now receive Big Pay. Free Employ- ment service, Positions waiting. Earn while learning. EZ low terms within reach of all. MONEY BACK GUARANTEE-NO RISK PROVED PLAN. Name, address and present occupation brings FREE ABILITY TEST AND BOOKLET. MM-2, 24 W. ACME STUDIOS, Dept. Hubbard St., Chicago, Ut. Always Insist on the Advertised Brandt

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NOW, MRS. MOUSE, FIND ANOTHER HOME...P.W. IS FILLING THIS CRACK! MAKES HOME REPAIRS EASY broken chairs loose casters — holes in floors floor cracks loose drawer pulle screw holes in plaster With Plastic Wood —the discovery that handles easy as putty and quickly hard- ensintowood—it’seasytodoan , expertrepair job. Youcan paint (| it, carveit—holds nails, screws. At paint, hardware, 10g stores, in 10g and 25g tubes, 357 cans. nicks ` COMPLETE: TAXIDERMY vac gs on ther DIPLOMA FREE OF OTHER COST Cost Due to (tremendous sales volume, Schmidt's Original $ E ! T Taxidermy NOW ONLY S1 COREE QU Eee) Fie eubert; GS nine Ta Has taught thousands to mount birds, animale, game h fil seven: books. v hole pourmen $1 Nothing more B Pay. All comes at once! mounting first day, eni o tage. — (Forei orders $1 cash.) If not 100 per cent salished, ‘tone funded at ence Gern CAMERA BOOK! Just out! Explains latest inventions, methods in photogs raphy and Home Movie Making, for funandprofit Offers | hundreds of .maz- ing, money - saving Bargains in new and used still, movie ameras 'Lenses, Films Exposure Mete: inlargers, Darkro ends, fish; make novelties. aoia everything photo- ^ graphic. Central of- fers you America’s most complete, varied stock of foreign and domestic merchandise from world’s leading makers: Eastman Kodak, Zeiss, Bell & Howell, Graflex, Geveart, Korona, Bausch & Lomb, etc. SAVE at Central! Satisfaction guaranteed or money back. We take your old camera and CEN in trade. Write for Free camera book! NTRAL CAMERA CO., 230 S. WABASH Dept. J-2, CHICAGO, U.S.A. PHOTOGRAPHIC HEADQUARTERS since 1899 When Answering Advertisements Please Mention February Modern Mechanix Tf it does, do some- thing about it] Get « raise in salary—but first get the training that will entitle you to this raise. Thousands of men in the same fix as you have gotten this training by spare-time study of an I. C. S. Course. Mail the coupon todayl INTERNA AL CORRESPONDENCE SCHOOLS Box 2317-P, Scranton, Penna. ~ Without obligation, please send full particulars about the subjeok before which I have marked X: TECHNICAL AND INDUSTRIAL COURSES O Architect O Diesel Engines O Architectural Draftsman D Aviation Eng. [0 Auto Mechanie O Building Estimating O Plumbing O Heating O Contractor and Builder O Air Conditioning O Refrigeration L] Structural Draftsman D Steam Engincer LJ Structural Engineer O Steam Electrio Engineer O Electrical Engineer LI Marine Engineer U Electrio Lighting O Civil Enginoor O Highway Engineer O Welding, Electric and Gag O Bridge Engineer O Reading Shop Blueprints D Bridge and Building Foreman O Telegraph Engineer O Surveying and Mapping O Telephone Work O Radio O R. R. Locomotives O Air Brakes O Mechanical Engineer H R R. Section Foreman L] Mechanical Draftsman R. R. Signalmeu O Machinist O Toolmaker H Chemistry O Patternmeker O Coal Mining O Foundry Practice D Navigation U Sheet Metal Worker Li Cotton Manufacturing Q Boilermaker O Woolen Manufacturing & Heat Treatment of Metale LJ Agriculture D Fruit Growing O Management of Inventions O Poultry Farming BUSINESS TRAINING COURSES O Business Management O Lettering Show Cards O Industrial Manage:uent O Stenography and Typing O Traffic Management DJ Civil Service Mail Carrier O C.P.Accountancy O Railway Mail Clerk O Bookkeeping D Grade School Subjects O Secretarial Work O High School Subjects J Cost Accountant O College Preparatory C] Salesmanship O Advertising O First Year College Subjects — — O Service Station Salesmanship O Illustrating C Spanish O Business Correspondence LI Cartooning O French DOMESTIC SCIENCE COURSES O Professional Dressmaking O Millinery and Desig: O Foods and Cookery D Home Dress D Tea Room and Cafeteria O Advanced Dressmaking Management, Catering D Pharmacy D Signs P —— RED — t € Address. ......... sess ———— "—— City....... State. Present Position. If you reside dn Cana Correspondence Schools "Canadian, Lii the International ted, Montreal, Canada 139

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PUANSUDIETEÀ Tool of l00l Uses g A WHOLE SHOP FULL OF TOOLS IN ONE For work on all metals, alloys, bone, resins, plastics, glass, stone, wood, ete. Uses 200 different accessories to grind, drill, cut, carve, sand, saw, * engrave, sharpen, clean, polish, etc. Saves hours of tedious hand work, Plugs in any socket AC or DC, 110 volts. STANDARD MODEL A sturdy little helpmate. Weighs 1 pound. 13,000 r.p.m. $10.75 postpaid, 3 Accessories Free. DE LUXE MODEL Fastest, most powerful tool of its type and weight, 12 ounces, 25,000 r.p.m. $18.50 postpaid, 6 Accessories Frec, GET A DEMONSTRATION at your Hardware, Department or Tool Dealer or order elther Model on 10- Days, Money-Back Trial. Catalog Free, CRAFTSMAN'S PROJECT BOOK Easy working plans for making many in- teresting and unusual projects, 25c stamps or coin, Chicago Wheel & Mfg. Co., 1101 W. Monroe St., Dept. H, Chicago, IM. ne (a ee O 810.75 Model O Project Book Ol Send C, O. D. Gi Send Catalog L] De Luxe Model IMI-2 Name .........esees € Ce e xir es Roe ce Address .......eeeeeeee eroesosoosesecuesesase X a dtes Ri n Fester Better jobs x Better Built Lower Prices Only Boats With Full Length Spray Rails Keep passengers perfectly dry—-even at high speeds. Catalog also shows today’s five most popular models of sailboats. Two big facto- ries. Prompt shipment. ab FOLE kind of * e kil Niger interested. 230 THOMPSON BROS. BOAT MFG. co. (87) nn "n MT St. PES! wis, either place CORTLAND. y. UICE ends tical Electricity in your own Home ‘Shop. No EQUIPMENT previous experience or advanced education is necessary. Money back if not satisfied. Send the coupon for full Informetion on this NEW, EASY WAY TO BETTER JOBS AND GOOD PAY. Lifetime FREE Employment Service to Graduates, RIGHTIN YOUR — " This FREE Book Tells YOU HOW, Age Novel Cigarette Automat [Continued from page 71] trick cigarette boxes, this one won’t be discarded very soon because you and your friends will never get tired of having cigarettes handed to you in this novel manner. The entire cigarette box can be made with ordinary hand tools, although a power jigsaw will simplify cutting out the bird. The drawer, cylinder end blocks and bird are all made of 12-inch stock, everything being 14-inch stock. , First make the 714 by 3%-inch bottom compartment, the sides of which are $$ inch high. Set sides about % inch in from edge of bottom piece. Make main board shown in the perspective and cut slots. The drawer is next. First drill the hole, then make parallel saw cuts for the trough, using a chisel to finish. The cigarette hopper should now be made a good fit around the drawer, yet allowing the drawer to slide freely. Transfer the bird design to wood by means of 14-inch squares, cut out, and then taper beak to about 4 inch at end. Cut out tail and attach. The parts are now ready for assembling. Procure or turn a wooden cylinder 136 inch in diameter by 2 inches long and on this mount the bird. This is done by cutting the heads off two six-penny finishing nails and driving them into both cylinder and bird in the manner shown. Mount cylinder in Slot “A” between end blocks shown in detail, using two nails as pivots with the heads cut off. On the under side of the cylinder glue and nail a 34 by 12 by Z-inch strip of wood to act as a stop. After fastening the hopper to the working board and in- serting the drawer, connect the spring and cord as shown in photos 1 and 2. Now tilt birds as if to pick up cigarette. The drawer will probably come out too far and to remedy this shave off the corner of the stop and shorten the cord until drawer opens the correct distance for bird to function properly. With this aecomplished, tack the end of the cord perma- nently in place and fasten the working board over the bot- tom compartment. Decorate the bird with enamel, blue with white wings arid eye-balls being a good combination if the rest of the box is done in walnut or mahogany. Flying The Subway Express [Continued from page 134] You begin to understand. Power is taken from a third rail running alongside the track; contact shoes on the car trucks feed current to the motor. If current were fed into one end of a third rail which is some fourteen to twenty miles long, voltage would drop so tremendously that cars a few miles away would be unable to operate. Consequently the line is divided into sections, each insulated from iis neighbor, each independently fed from the power house. Thus power can be cut off from any section without affecting the others. Those S. B. markers might just as accurately be labeied "Life and Death." The white light above one of them suddenly flashes red. Instantly the motorman shuts off his power, applies his brakes. Something has happened ahead. An emergency, possibly a short circuit, Men are working on the dead third rail, for power has been shut off from the section. Our motor- man has been prompt enough to halt the train before it rolls into the dead section. If the car had crossed the insulating break before stop- ning, service lights would have to be switched off instantly, leaving the train illuminated from batteries alone. Other- wise the rear contact shoes, touching the live third rail, would transfer current through tbe forward shoes to the dead rail which workmen are repairing and they would be electrocuted. The very spirit of the subway is one of galvanic life, but death is forever trying to crash the turnstiles. Human ingenuity keeps the grim reaper persistently at bay. A bit wryly, the motorman demonstrates the "dead hand control” as we roll in for a stop at the first express station. Rising up from the end of the control handle is a spring- actuated knob or butten, Only when it is held in depressed position can current flow through the controller. The instant the motorman fails to hold it down, the knob flies up, shuts off the power, applies the brakes automatically, When sub- way trains following close on each other's heels and racing along as fast as 48 m. p. h., the dead man control prevents frightful collisions should the motorman collapse at his post. Death in different guise rides ahead of the motorman each time he brings his train into a station. Schedules must be maintained; he does not shut off power until the first car reaches the near end of the platform. At any instant, out of the throngs of humanity packing the platform, a human [Continued on page 154] 140 Accept No Substitutes! Always Insist on the Advertised Brand!

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Know Electricity as Experts Know It—and Get an Expert’s Pay Recovery has begun! ‘The months ahead are charged with signif- tance and expectation. What will you do to get the jump on the other fellow? Thousands of men have used The Croft Library of Practical Electricity The Croft Library is & complete electrical educator. It is founded on prnctice—on 20 years of shirt-sleeve experience—on work as It Is actu- ally done. It is jammed from cover to cover with the kind of hard. headed facts you want. Written so that the beginner can easily understand it, yet so sound, so thorough, that It Is the gaily guide of 59,000 highly paid clectrical workers and engineers. Croft tells you the thinzs you need to know about motors, generators, armatures, com- Tnutators, transformers, circuits, switchboards, distribution systems— electrical machinery of every type- Witing for light and power—wirlng of finished buiidings—underwrlters' and municipal requirements—il- lumination in its every phase—the most Improved methods of lighting— lamps and lamp effects, etc.—how to do a complete job, from estimating it, to completion. No money down—easy payments Fill in und mail the coupon attached and we will send vou the entire Set of seven volumes for ten days’ Free Examination, We take all the Flsk—you assume no obligation. If you decide to keep the books, send $1.50 in ten days and the balance at the rate of $2.0 Send the coupon NOW and see the books for yourself. | FREE EXAMINATION COUPON | McGRAW-HILL BOOK CO., 330 W. 42nd St., New York | a month. Send me for ten days’ free examination the Croft Library of Practical Electricity. If satisfactory I will send you $1.50 in 10 days and $2.00 monthly until the price of $19.50 is paid. wanted, I wiil return the books potpala. shipment write plainly and fill in all Lines.) If not (To insure prompt | Name Position -----...--. | Name of Company. Plow Seed Cultivate Gardeners, Florists, Nurseries, Fruit Growers, Poultrymen. Mow Hay | ...2 & 2 Cylinders L High Wheels. Rubber or and Lawns Steel Tires. Walkor Ride. (3 : Do Belt Work—Free Catalog IRA STANDARD ENGINE CO, X Minneapolis, Minn, Philadelphia, Pa, NewYork, N.Y. 4023 Como Ave. 2532 Market St. 278 Cedar St. "UP T0 “DEAL DIRECT... FACTORY PRICES! Manymodels to se- lectfrom:AC-DC;All-Wave; tuning:car radios i that operate like city radios Send posteard for NEW Bargain Catalog FREE. 30 BDAY TRIAL plan and agent-user proposition! GOLDENTONE RADIO CO. DEPT. G2, DEARBORN, MICHIGAN MAKE MONEY IN YOUR WORKSHOP The Modern Mechanix, Blueprint Catalog describes 125 projects that can be constructed in the home workshop and so'd at a good profit. Send a 3c stamp today for your copy of this valuable MODERN MECHANIX PUBL, CO., Fawcett Bldg., Greenwich, Conn. UI |" MECHANICS & WELDERS oS Auto Mechanics and Welders are in big de- mand. Complete courses in are and Wiite D acetylene welding, metal finishins, 7 body and fender bumping, spray paint- jE Pr Ing. Special low rates, Write today. FREE MICHIGAN TRADE SCHOOL (ay anew 3763 Woodward Ave. Detroit, Mich. When Answering Advertisements Please Mention February Modern Mechanix with SMOOTH-ON No. 1 HY go to an outsider, await his con- venience and pay a high labor charge for what you can do quickly, casily and at almost no expense? When a leak starts in a boiler, furnace, heater, tank, threaded or gasketed joint, a smoke or hot-air duct, etc, or when wood screws, bolts, nuts, handles, etc., refuse to stay put and hold tightly, make the repair yourself, and keep the money in your own pocket, Smooth-On No. 1, requiring no heat, special tools or previous experi- ence in its application, affords a de- pendable means for doing exactly this. Used to stop leaks of water, steam, gas or oil, to tighten loose hinges, locks, handles, connections, etc., or to anchor shelf brackets, cabinets, fix- tures, partitions, posts, etc, in ma- sonry, Smooth-On No. 1 hardens into metal quickly and becomes stronger than the surround- ing material. Smooth-On No. 1 seldom costs over a few cents per appli- cation and can be used in dozens of places in your home and on your car, with an annual saving that amounts to a substantial sum. The Smooth-On Home and Auto Repair booklet, sent free, explains where Smooth-On should be used and how applied for best results with least effort, and is filled with helpful advice and diagrams for the guidance of home mechanics. Mail the coupon for your copy and get Smooth-On No. 1 in 7-oz. or 1 or 5-Ib. can from any hard- ware store. Your first Smooth- On application will probably more than repay the small investment, and you will be ready for many jobs that otherwise might be costly or annoying. nuoc a Kg — É SMOOTH-ON MFG. CO., Dept. 69 574 Communipaw Ave., Jersey City, N, Ja a Please send Smooth-On Home Repair ook, Name ..... Stopping leak of crack eo * 9 fe] 4 NOH Tightenin loose kandle Anchoring in masonry Home am AUTO REPAIRS Write for : FREE BOOK Address , 14

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JACK SMEAD, Service Mor. ILL. AUTO CLUB, SAYS: or: Gad IN GASOLINE” J] On Son Francisco To Chicago Road- Test with Stransky GAS ECONOMIZER Automobile owners are reporting GAS SAVING, MONEY SAVING Tesults with the use of a wonderful new improved auto gas economizer, which fits any ear, costs no more than a good wrench and anyone can lin ten minutes, Jack Smead, € Manager of Illinois Auto- mobile Club says, “I placed a Packard and in a drive from San Francisco to Chicago with another kard of the same and model, I had a saving of $19.38 in gasoline over the other car." Tt helps motorists cut gus &nd upkeep eosts, and thus SAVES GAS, SAVES MONEY, “AUTO GOES 32 MILES ON 1 GALLON OF GAS, 44 Says, G. Kuenkel “After installing a Stransky, now getting un of 32 MILES PER GALLON” says C, A. Anderson, “I can make 32 miles on a gallon €f gas, where I made 23 before," says Eddie Mashak. NEW IMPROVED GAS ECONOMIZER SENT ON TRIAL For 30 DAYS—Costs Nothing if it does Not Save Gas Yes, we are willing to send this new improved gas economizer to any motorist to test on his car on 30 days trial, the motorist himself to be the judge of its gas saving, money saving value to him, and if it does not save gas, save money for him, ii costs him nothing—but, that's not all, we will also pay a bonus for testing it if not delighted—so you can't lose, With- out obligation send name and address on coupon below—or paste on lc postcard and mail. J. A. STRANSKY MFG, CO. B-600, Pukwana, So, Stransky on m AGENTS SALESMEN BIG MONEY Startling Demon- Strator, T, M. Wiley says ''Cleared $39 in 3 Hours—on previous Saturday I cleared $18.” Get unusual money-making plan offer of NOQ-COST SAMPLE io sales- men for a little easy work, spare time or full Write qulck— be first in your lo- Dak. cality, FREE OFFER Coupon dS STRANSKY MFG. co. B-G00, PUKWANA, S. DAK. Without cost or obligation, send your a TRIAL OF B BONUS OFFER. r FER and GUARANTEED CHECK a HERE B L| if interested g in NO-COST SAMPLE and money making offer. I Potential Gasoline Mileage ACCORDING to an article by the president of the world's largest motorresearch corporation, there is enough energy in a gallon of gasolineif it were converted 100% in mechanical energy to runa four cylinder car 450 miles. NEW GAS SAVING AND TOP-OILING INVENTION Astonishes CAR OWNERS A Marvelous Device has accom- plished wonders inutilizing a por- tion of this waste energy. Itsaves gasoline, gives better mileage, re- duces carbon formation, creates more power, gives quicker starting, snappy pick-up and a smoother running motor. Saves many repair bills. Big Profits and Free Offer! ... To obtain national distribution quickly, men are being appointed everywhere to help supply the tre- mendous demand, Free samples furnished to workers, Write today for this free sample and big money-making offer. Diamond Fuelizer, Dept. 114, 600 High St., Akron, Ohio 142 Accept No Substitutes! Stamps, Rail Anniversaries [Continued from page 70] issue; the modern example, a streamliner, was shown on the higher values. In 1934 Germany followed suit, showing its first and its then-latest locomotives on a special issuc of postage. year later, 1937, France followed suit, with the first and latest types. Other countries have issued stamps showing railroads, thus marking (as with Nicaragua) the inauguration of new lines. Still other countries like Sweden “have produced stamps to illustrate the locomotives which were used, are used, or both, in the land. Many countries have produced stamps showing early, as well as late locomotives and trains, merely as attractive designs for their issue. Railroads and locomotives, particularly the latter, seem to be very popular as designs for postage stamps. The stamp collector who has interests along such lines will he able to form a fascinating album, displaying railroad and locomotive picturing postage adhesives! The English "Royal Scot" locomotive illustrates a popu- lar and fast type of steam-locomotive such as depicted on the Swedish stamps, which appeared in 1936, the 40-ore value particularly. From the photo and stamp upon it, the collector may discern the differences between the European and the Ámerican types of steam locomotive. The story of the railroad and the development of the locomotive, as well as its spread throughout the world, is being nicely told by such stamps of the several countries issuing them. Neither England nor the United States has yet entered the lists, although the story is otherwise quite pictorially complete with the issues we already have. The 1.50 franc stamp of France (1937) shows one of the latet of the streamliners, while the San Marino 20 centesimi value pictures an electric locomotive. The Spanish stamp shown may depict the "last train from Madrid!” MM Short-Wave Transmitter [Continued from page 102] The antenna coupling unit shown is the one actually used with this transmitter, but other arrangements may be more satisfactory with individual antennas. A single piece of wire approximately 160 feet long, including leadin, was used, and the coupling unit shown worked satisfactory. For complete information on this subject, the builder is referred to the chapter on antennas in the “Radio Amateur's Handbook." As the set approaches completion, some builders find it almost impossible not to rush the work a little to speed up that moment when it finally can be turned on. Speeding up work is all right, but occasionally the jol started as a masterpiece of good workmanship becomes “haywire.” And as would be expected, more mistakes are made during this period than when the work is first started. A little extra time spent on doing a good wiring job will pay good div idends. However, when the set is finished and ready for the test, take out a few minutes and check all the wiring. If every- thing is as it should be, turn on the power to the filaments. Let the 866’s and the T55 burn for about thirty minutes before applying plate power. Next, apply voltage to the oscillator. The needle of the milliammeter probably will swing over to full scale, indicat- ing that the tank circuit is not in resonance. Turn the oscillator tank condenser (C4) until a point is reached where the needle of the milliammeter will drop sharply to about fifteen milliamperes, indicating that the circuit is in reson- ance. If a single loop of wire, slightly larger than the diameter of the tank coil, is connected to a flashlight bulh, and held near the tank coil, the bulb will glow when resonance is reached. If a milliammeter ís not available, the flashlight bulb can be used alone as a means of checking operation. . If however, resonance is not indicated as the condenser is turned, check the wiring again. Also, the crystal may not be clean. Wash it off with carbon tetrachloride to remove any trace of grease which might have been left on the surface when it was handled. Assuming that the oscillator stage is working, the next step is that of neutralizing the amplifier. With the T55 filament lighted, and the oscillator in operation, disconnect the positive lead of the amplifier at the power supply. Hold the loop of wire and flashlight bulb close to the amplifier tank coil and turn the tank condenser (C9) until the bulb lights brightly. Then turn the neutralizing condenser (C6) until the bulb goes out. At this point it may be necessary to retune the oscillator stage for maximum output. Then with the flashlight bulb still in position, turn C9 again until the bulb again lights. This time it may not be as bright as it was the first time. If the bulb does light, turn the (Continued on page 154] Always Insist on the Advertised Brand!

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Hish School _ atome | Go as rapidly as your time and abilities permit. @ Equivalent to resident school work—prepares for entrance to college, Standard H. S. texts supplied. Diploma awarded. Credit for H. S, subjects already 3 completed. Single subjects if desired. Bulletin on request. E Specialized training is absolutely essential to Success today. Over $ 3 150 noted Educators, Engineers and = Business Men helped prepare our spe- Cou rses cial instruction material, used by many resident schools and colleges, k U. S. Navy and Province of Mani- toba, Can. Train at home for best-paying lines as listed below. No interference with present earn- ings while preparing for better job. American School, Chicago Mail Coupon for Information—No Obligation American School, Dept, H-228, Drexel at 58th, Chica, Tell me how to tr: "i success in line checked. d e - .,L) High School Course in 2 Years _ 2 Air Conditioning Electrical Refrigeration Architecture and Building Highway Engineering Automotive Engineering Liberal Arts (College) Lj Aviation Mechanical Engineering ess Management Private Secretary Engineering Professional Accounting Complete Law | inci. C. P. A. Coaching Diesel Engineering Radio and Television Drafting and Design Salesmanship _ Electrical Engineering Steam Engineering Mokes lumber, shin- ales, lath, ties, crates, LZ» a TURN TREES INTO i^ MONEY WITH A BELSAW Three capacities: 10, 14 and 20 1 for: guo ms feet, Accurate set works, posi» ative dogs. Hand or power feed. Runs on low ber wer—Many owners use old auto engine, 0 Paya” for Itself quickly—thousands in commer- S cial service, everywhere. Write for free lumber fiandbook and catalog of mills, Supplies, tools, saw tables, and woodworking equipment. ELSAW MACHINERY CO. . 834-N Davidson Bldg. Kansas City, Mo. BIED-UR- OWN E COASTER$-MIDGET AUTOS- SCOOTERS” DISC WHEELS equipped with 10’x234” e i w (GOODRICH-GOODYEAR-FIRESTONE) Balloon Tires offered at LOWEST PRICES Also larger tires and wheels— Motors, ete. BILD-UR-OWN DEVICES Dept. B-2 Best Support for Rupture h the Human Hand Why worry and suffer with that rupture any longer? Learn about my perfected invention. It has brought ease, comfort and goppiness WRITE TODAY FOR PRICES | Chicago, IIl. 5237 Lake St. thousands who suffered from reducible rupture. Jt has an Automatic Air Cushion which softly yet securely holds the rupture in any position. No steel springs or pads. No salves or plasters. Durable, cheap. Sent on trial to prove it. Beware of ions. Never sold in stores nor by agents. Write today for full mation sent free eb sealed envelope. cO., G-D State St., Marshall, Mich. fni BROOKS When Answering Advertisements Please Mention February Modern Mechanix WIREHAIRED m d i € Tough, wire-like beard absolutely requires Gillette Blades. That's because these super-keen blades are made for heavy duty work." No imi- tation—no substitute—takes stubborn stubble off so clean, close and comfortably. And re- member, Gillette Blades, precision-made for your Gillette Razor, cost less than one cent a day. @ More Gillette-made Blades were sold dur- ing the past 12 months than ever before in a similar period. Thank you men, for Gillette’s greatest year! Wh make a proving groun of your face? Demand Gillette Blades. Repu- table mer- chants give LESS you what THANIKA DAY\ YOR 35k fort à buys the worlds | gz finest blades REMEMBER IT’S: YOUR FACE Precision-made for each other MORE SHAVING COMFORT FOR YOUR MONEY 143

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i have a Fine Job » thanks : Am I glad T took up draft- ing! I used to slave at a :mere job once. Dut now I'm in a fascinating pro- fession... where the work is easy, pleasant... where every job is a new adven- ture. Believe me, it's a first rate thrill when you help design a new machine, * a new building—when you actually create things! And jI'm well paid, too. I’m satisfied! LEARN AT HOME IN SPARE TIME I didn't go to college. Only to grade school—and had ino special talent. But the *- C. T. C. lessons were so simple I caught on easily! = nn “ct And this “at home in spare time” training is inexpensive. You can afford it—terms are so low. SEND FOR TRIAL LESSON Act now—don't rob yourself of a better job and higher salary. Find out for your- self how you can master drafting—in the shortest possible time . . . at least expense. Send the coupon today for the FREE LESSON, It wl rove to you beyond doubt that the C.T.C. system s astonishingly simple. After examination, you'll Say,''"This college work—at hom You'll ad- mit that C.T.C., with 35 years of progress back ot It, is perfectly equipped to traln you. This come plete draw- ing outfit, In- cluding table, is given each Student. These ate first class tools =the kind experts NO MORE JOB AND PAY WORRIES More draftsmen are needed every day—by steel milis, auto plants, Tailways—by Deisel and Air Conditioning plants. Draftsmen are hired first—for every bridge, factory, ete., must be planned on ihe drafting table. Draftsmen come in contact with engineers, industrialists, financiers Make associations that lead to promotions . . . to your own business. Send now for complete information on how you tco can share in the great advantages that ie offers draftsmen. Use the Coupon. Get your FREE TRIAL LESS CHICAGO TE I B263 Tech Bldg., 118 CHE AL ae GHEE Ilinois B263 Tech Bldg., 118 E. 26th Street, Chicano, Ilinois Please send me FREE Trial Lesson in DRAFTING and show me how I can prepare for a good position in spare time AT HOME. @ Would you like to take a trip to Italy next summer, all ex« penses paid? The opportunity is yours. If you have never tried to play an accordion, you areeli- gible to enter Soprani's nation- wide aptitude contest to win one of these glorious vacation trips. No special qualifications re- quired. It is open to all ages; juveniles will not have to com- pete with adults. See your SOPRANI ACCORDION dealer. Register imme- diately with him. Or write direct for application blank. But you must act at once. No applications accepted after February 7. Final Contest July 9th. 198 SOPRANI, INC. P*"* iiaeo, uineis s n Nunzio Amazing rubber mold-making outfit makes perfect flexible molds of plaques, ash trays book-ends, etc. Molds cost from 6c to 25c each. Each mold makes hundreds of novelties and gifts to sell up to $1.00 aplece! No experience necessary. Everything fur- nished. Start profitable business in your home . sell to stores, frlends, resorts, road stands or by Jall-CNOW! Make BIG MONEY full or spare time. Write for complete FREE details and easy instruc- tlon: SO-LO GO-MA MOLD CO., Dept. B-834, Cincinnati, Ohio. -Ala j =Ele Se: 3l x nc New Radio Ecetia Ares SAVE MONEY on Technical Books! Newest, popue lar-size books now yours at Low Prices, only 206 up! By nationally known authorities! Crystal-clear. Profusely illustrated. Set includes Short Courses in Radlo, Electricity, Mathematics, Radlo Trouble Analysis, Electrical-Radio Dictionary, How to Start Electric Repair Shop, Ilow io Bulld Experimental Laby. Work Bench, dio E perimentss Electrical Expr., eres 13-Yol Sen On. . or compie! e " MAILED POSTPAID! fivrary: Yor mail card for" Free Folder describing our full line of Low Priced Books. ORDER TODAY? ELECTRONIC PUB. CO., Box 323-V, Lincoln, Nebr, MAKE MONEY IN YOUR WORKSHOP " Build furniture, auto trailers, canoes, iceboats, cruisers, sailboats and electric refrigerators described in FREE BLUEPRINT BOOKLET g MODERN MECHANIX PUBL. CO., Fawcett Bidg., Greenwich, Conn, A CHEA e e the [c4 J C m= , : t OOK and HEAT, Miror Wood F ERU Mae or Furnace—HOTTER DN NE opi ei YE —CHEAPER-—No Dirt LAU or Ashes—Twice the Heat Quick at SMALLER COST, COOK and HEAT for LESS Amazing oil burner AGENTS burns cheap oll a new bled e PLE ED. Salesmen erating orclogg H x Sis or vise | BIG MONEY | /r i^ Silipa Into SENT ON TRIAL Eurum Muere uickly by what it pavesat Sur EE Ofer ek FURNACE. 1S REE SAMPLE 29.5. be Arst to learn bow to end drudgery, dirt and ashes of coal and wood and make big money, spare or fub Ume mal) 1c posteard today. UNITED FACTORIES, B-G00 Factory Sullding. Kansas City, Me: Seve CHEAP Ol 144 Accept No Substitutes! Alceays Insist on the Advertised Brand!

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C DISSTON FINEST À

| 5000 NOVELTIES niy cata! i q entaths Over Sods Beek : thered from every corner of \ * : e world. Joke articles. puz- A < cuu les, cameras arms, punch 3,500 THustrations Bical “novelties, T ual . e-UD A æ Nearly 600 Pages \ struction kits, electrical neve A low priced radios, r Cov 114” Thi te

fireworks. unusual jewelry. P T . 24 pages musical items. ‘24 panes of jewelry. Banks, cameras, guns. S1 pocket radio: 25c home .,,Sen edition or complete, ‘bound, lis rary edition. JOHNSON SMITH &CO. \ gga Dept. 802 Detroit, Mich. Amazings Things You’ve Never Seen Before

This New P-A @ Such beautiful tone, and so easy to play! Just touch a à 4 key and blow nor- mally; you can't miss, Noih- ing to compare with these new Jj P-A Saxes, Clarinets, Trum- pets, and other P-A instru- ments. Fully guaranteed; your Success assured. See your ) music dealer or write direct for beautiful, free book. No obligation. Easy terms, 1286 /PAN-AMERICAN 230 P-A Bullding Elkhart, Indiana RAISE POULTRY FOR PROFIT START AT HOME. MARKET WAITING, Garage, barn or backyard all that is needed. Learn latest methods from our Home Study Course and put cash in your pocket every day. We train you, help you. Get facts about our unusual offer NOW! Men and women making money in every state—town and coun- try. Send for illustrated FREE BOOK today! NATIONAL POULTRY INSTITUTE CD Dept. 138-C Adams Center, N. Y. She Got $400" @ Times change! Homecraftsmen, like mechanics, are buying the best saws made. The thriftiest home workshop circular saw is Disston DeLuxe. On any job, it means easier, more accurate cutting. It gives a lifetime’s satisfaction. DeLuxe Cross-Cut—Rip—Combination 6"(15"hole),$2.70 8” (15", 94", 34" hole) ,$3.50

7" OL" hole), $3.10 10” (56",34" hole) » .. $4.50 DeLuxe Hollow Ground Combination 6" (V;"hole),$4.30 8” (14",54",34" hole), $5.40 7" (V&"hole),$4.90 10” (96",34" hole) . . . $6.90

VASA AAA wri aan P PPS Above. D-23 Disston. One of Also, D-8 Disston. Famous, world around, as the "Saw [ ; the finest hand saws. Light- for a Half Dollar MEE 6 en E A will pay. CASH for] {OLD COINS, BILLS end STAMPS} POST YOURSELF! It paysI <2 I paid £400.00 to Mrs. Dowty Ch of Texas, for one Half Dollar; J.D. Martin of Virginia $200.06 As for a single Copper Cent. Mr, SK Manning of New York, $2,500.00 for 6752 x55" oneSilverDollar. Mrs,G. F. Adams, Ohio, received $740.00 for a few old coins, I will pay big prices ting. Beautiful finish, 26" length oe cece eee $3.85 Most Carpenters Use.” Wide blade. Skew back. Same in narrow bladefor home work- shop. 26" length .. . $3.50 ASK DEALER for DISSTON SAWS

= æ æ = FREE MANUAL e oe — Write us for "Saw, Tool and File Manual” telling How to Choose and Use Saws. FREE. for all kinds of old coins, medals, bills and stamps. | WILL PAY $100.00 FOR A DIME! . » 38048. Mint: $50.00 for 1918 Liberty Head Nickel (not Bufalo) c^ snd hundreds of other amazing prices tor colns. Send 4c for Large Illustrated Coin Folder end further particulars, It may Henry Disston & Sons, Inc., 208 Tacony, Philadelphia, U.S. A.

3nean much profit to von, Write today to e Dr — ————————— B. MAX MEHL, 150 Mehl Bldg., FORT WORTH, TEXAS (Largest Rare Coin Establishment in U. $.) ELT E ———M— When Answering Advertisements Please Mention February Modern Mechanix 145

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Are Available trained men are in demand and earn good money in these fascinating well- paying trades. This is not a correspondence School—no books —no lessons. Don't look for a job—TRAIN FOR IT. Read below how a McSweeny-trained man made good. e AUTO MECHANICS € AVIATION MECHANICS e DIESEL MECHANICS Collision Repair (Complete) Body and Fender Repair Auto Painting € WELDING —Arc and Gas You Get Actual Shop Training Work on real equipment with real tools. In a few weeks you hould be trained by actual work to hold down a Good Pay Job. 1801 E. 65th St., Cleveland, O, Dear Mac—Imme- We get v diately after leaving school I went to work for many letters United Motors and am now located in Cleveland where I hold a good position. I have been able to f| take care of the most complicated electrical jobs. I thi i have done fine considering I had no experience before coming to your school, t Todd LEARN NOW—PAY LATER! We will give you complete information on how to get your training now and pay for it later out of your earnings, FREE Write today for Big Free Book. Get the facts about jobs; and low Tuition Offers. Mailing the coupon does NOT obligate you. It obligates ME to tell YOU how you ean train for Big Money in a few short weeks, Address Dept, 11-50, McSWEENY SCHOOLS DETROIT, MICH. and KANSAS CITY, MO. Pei Our School Nearest D like this Meseeeny fae Buildings | The finest of their kind. Every mod- WŒ. ern facility for thor- : ough instruction. KANSAS CITY = i : DETROIT = m ——— — x es Xm - m mí: McSWEENY TRADE SCHOOL Dept. 11-50, Detroit, Mich., or Kansas City, Mo. Without cost or obligation send me your big FREE Book, Il am interested in the course on Name Street Town —— State Ago Copying Device [Continued from page 114] tape and focus the camera on it. Adjust the angle of the light supports so that the copy is evenly illuminated and is not reflected back into the camera lens. Mark lines on the bottom batten along the sides of the light supports so that this position may be quickly arranged on future occasions without having to experiment. The exposure on Panatomic film in such a device ranges from % to % second at f. 11, de- pending upon the tone of the print to be copied. Once the proper exposure is found, note it on the back of the print and use it in judging the ex- posure on future copies to be made. When using various lenses for copying it is handy to know how to get equivalent results with different lenses and, in copying, the stop numbers on the lenses are sometimes a poor guide. A better way is to use the following procedure: Set the stop on the lens to correspond with the focal length of the lens. That is, set a lens marked f. 6.3 to f. 6.3 even if it is a lens that has an f. 45 opening. If you have a 10 inch lens, set it to f. 10, even if it opens to f. 8, and so on. Now focus the camera and get the image on the ground glass the size and sharpness desired and measure with a ruler the distance from the lens to the ground glass. The reading in inches will be the actual f. value. In other words, :f the distance from the lens to the ground glass is 11 inches, then the camera is operating at f. 11 and the exposure will be exactly the same as for any other lens which has been so adjusted and which measures 1l inches from lens to glass when focused. This permits the use of different lenses without sacrificing accuracy in results. Lamp Tilts To Any Angle [Continued from page 107] covers the joint. and shellacked. The base is made of plaster of paris. Make a cardboard mold 4 inch square, and pour in the plaster one inch thick. In the center insert a screw 114 inches long, 4% inch diameter, and 20 threads to the inch, After the plaster has set give the base a coat of silver paint. Every amateur has a tilt-top attached to his camera tripod. If not, one may be obtained for a dollar. Screw the tilt-top onto the base, and force the threaded stud on the head of the ball joint in the hole in the pine block, A bulb is inserted in the socket, and the lamp is ready for use. It can be tilted to any angle and will prove a valuable asset to any darkroom. The cover is likewise stained By using an optical instrument—the spectro- scope—to investigate the chemical composition of iron, two chemists in an iron foundry can do the work that kept six chemists busy when chemical analysis of the iron was made, 146 Accept No Substitutes! Always Insist on the Advertised Brand!

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A. C. GENERATOR PRACTICAL changes for automobile See our advertisement at Autopower. generators. bottom of page 131. ADVERTISING AGENCIES ADVERTISE: Get mail-order business, agents. Free assistance. _ Free Ad- Guide of newspaper, magazine, circula- tions, rates, mailing-lists. Chicago Ad- vertising Agency, 22 West Jackson, Chicago. ADVERTISE: 24 words in 250 news- papers $10. Lists Free. Advertising Service Bureau, 4515-B Cottage Grove, Chicago. 33 WORDS, 25 Magazines, Three Months, $2.00. Goodall Agency, 742 Market, San Francisco. IREE NEW advertisers rate guide. Drown Advertising Agency, 140 South Dearborn. Chicago. AGENTS WANTED HOW Would You Like To Own a Coffee Agency netting you up to $45 in a week? I'll send everything you need on 30-day No-Money-Risk Trial. New Ford car given you as bonus. Details free. Albert Mills, 8826 Monmouth, Cincinnati, Ohio. AGENTS: Smash go prices! Santos Coffee 12c Ib. 4-oz. Vanilla 8c. Razor Blades 10 for 8%c. 100 Sticks Chew- ing Gum 12c. 150 other bargains. Premiums. Experience Unnecessary. Carnation Co., MN, St. Louis, Mo. IF YOU agree to demonstrate I'll send you Free a big stock of actual samples food products, home necessities, etc., and show you how to earn up to $3.00 in an hour. Blair, Dept. 683-R, Lynch- burg, Virginia. PROFIT with new products. Make, sell, repeat. Analysis. Research. Guar- anteed formulas.. Biggest catalog free. Special prices, leads. Gibson Labora- tory, Chemists, CE-1142 Sunnyside, Chicago. GOLD Reflecting Window Sign Let- ters. Penny Each. Large Sizes. Easily Applied. New Styles. Absolutely Beautiful. Free Samples. Atlas Sign Works, 7941G Halsted, Chicago, Ill. LARGE Profits in your own business. Sell new and used clothing, bankrupt stock. Experience unnecessary. Every- thing furnished. Details free. Publix, 558-GM Roosevelt, Chicago. STRANGE Chemical wallpaper like magic. cleaning drudgery. Women amazed. Hustlers cleaning up. Details Free. Kristee 129, Akron, Ohio. 1000 BARGAINS, Drygoods, Notions, Drug Sundries, Specialties. Novelties. Agents undersell stores. Free catalog. Jobbers, Dept. 2698A, 930 W. Roose- velt, Chicago. eae M GEH. c ecu c uri ri BIG Money Applying Initials on Auto- mobiles; $1.45 profit on each sale. Write for particulars and free samples. Ameri- Sponge cleans can Monogram Co., Dept. 11, Dunellen, * New Jersey. BUSINESS Proposition Resilvering Mirrors, Autoparts, Reflectors, Making Chipped Glass Signs. Write Sprinkle, Plater., 850, Marion, Indiana. SIGN Letters for Store and Office Win- dows; 500% profit. Free Samples. Metallic Co., 448 N. Clark, Chicago, When Answering Advertisements Please Mention February Modern Mechanix Banishes house- ! *"TERE-UP" Popular Parlor Golf Game. Dollar. Agents wanted. Pippel, Pub- lisher, Grandhaven, Michigan. AMERICAN POLICE IU JITSU 13 KNOCKOUT Blows without use of fists, by internationally famous Jiu Jitsu instructor. Send 15 cents. S. J. Jorgenson, 291 Maritime Building, Seattle, Washington, AUTOMOBILES 60 SECONDS to Attach Present Tire Chains. No jack, same advantages, inclines or snow no obstacle. Last lifetime. Tested 10 years. Postpaid $1.50 or pay Postman $1.25 plus postage. Belco, 136 Balch Street, Beverly, Mass. ECONOMY! Performance! Mileage! Semi-diesel conversions for gasoline motors, $5.00 up. Manufacturer’s written guarantee. Learn hasic facts from free literature. Houston & Logan Conversions, 1719 Addison, Berkeley, California. SEMI-DIESEL fuel oil conversion units for auto, truck, other gas motors save 75% fuel cost. Units low as $5 guaranteed on Free Trial Offer. Agents Wanted. Free details. — Dies-I,-Gas, 3009 Foothill Blvd. Oakland, Cali- fornia. MIDGET Racing Car. 100 m.p.h. Build with our plans, parts. Details for stamp. Shipps, Box 543-B, Zanes- ville, Ohio. AUTO Owners—Safety Reverse Light $1.12. Automatic. Give make, year. Century Co., Box 127, Racine, Wis. AVIATION GET INTO AVIATION. Air trans- port pilots get up to $7,000 per year; mechanics, $2,500. Learn at this Gov- ernmént approved school, Write for complete information. State age. Lin- coln Flying School, 4002 Aircraft Bldg., Lincoln, Nebr. HEATH Motor Manual, conversion, installation, trouble shooting data, invaluable to Henderson motorcycle and Heath owners, $1.00 or C. ©. D. Heath Aviation, Benton Harbor, Mich. FREE AEROPLANES with motor purchase at $149.95. Easy terms— $12.50 down. Aeroplane—sled pro- pellers $2.98 up. Sensational values. Illustrated information 25c. Universal Aircraft, Fort Worth, Texas. AVIATION Apprentices. Good Pay— Big Future. Write, immediately, en- closing stamp. Mechanix Universal Aviation Service, Strathmoor Station, Dept. C, Detroit, Michigan. complete overhaul, | FLIGHT Photo's modern planes 8x10 glossy—for framing—35c each. Get yours free, details and list a dime. Air-Foto, 600 Michigan Theatre Bldg., Detroit, Michigan. INEXPERIENCED workers, apply for aviation jobs now. Fall salary while learning. Details for stamp. Airploy- ment, Box 553, West Los Angeles, Cali- fornia. Classified Advertisements Rate for classified ads, (8c per word (include name, address and all numbers), per insertlon, accompany order and be received in this office January Ist for the March issue (on sale January 28th), Mgr., Modern Mechanix Hobbies & Inventions, 1501 Broadway, New York City. : COD. .PLASTEX Industry Minimum 10 words, Cash must Address Classified AERO-SLEDS for ice or snow trans- portation, open and closed models, supplies. Send dime for details. Adastik Bros., Grand Rapids, Mich. BLUEPRINTS METAL TUBE Midget Radio. the last word in compact radio receivers. You can construct this set even though your knowledge of radio is limited by follow- ing the large pictorial blueprints avail- able, from Modern Mechanix Publ. Co., Greenwich, Conn., at 50c postpaid. BOATS LATEST Boat Sensation: New 20 Ib. Mead Sportsmans Ki-Yak assembled at home easily, quickly from complete factory-cut kit. $6.00 paddle now given with yours—if you hurry! Rush dime for catalog with pictures, description i.e. Mead Gliders, Dept. MC-28, Chi- cago, Ill. BOATS: New and used for sale. Take your pick. Send 25 cents Coin for complete list. _ Seashore Advertising Agency, Box 8, Beachwocd, New Jersey. CENTERBOARDS-— we supply them in brass, aluminum and iron. Estimates given, write us. Mar-Craft, Box 62, Maplewood, N. J. BOAT Bottom Paint. Finest quality. Red $2.25, Bronze $4.50 per gallon Small, 301 East 207th St., New York, N. Y. ICEBOAT parts $24.75. Skate sails 7 . Try-Sail Company, Patterson, New York. BOOKS & PERIODICALS SPORTSMEN’S MANUAL—The out- doors man's guide containing scores of practical articles by America's leading outdoor writers, covering every phase of fishing, hunting, camping, and trap- ping. This book, edited by Robert Page Lincoln, wil] make that next vacation a dozen times more enjoyable. Price $0c at your newsstand, or order directly from Modern Mechanix Publishing Co., Fawcett Bldg., Greenwich, Conn, NEWEST radio, electrical experiment books, 20c up. Amazing values. Cata- log free. Electronic Publishing Co., Box 323-Z, Lincoln, Nebr. BUSINESS OPPORTUNITIES needs manufac- turers on small scale and for big pro- duction of Art Goods and Novelties in Plastex and marble imitation. Cheaply and easily made in our guaranteed rubber moulds. We cooperate in selling goods. You are just in time for big 1938 wholesale season now starting. Interesting booklet mailed free. Plastex Industries, Dept. R, 1085 Washington Ave., New York. LOCAL, business—mail order business —pep for your present business. Authentic and inspiring folio "Business Development" reveals secrets of what you can do to put over your cherished dreams. Full time or spare time. Gets the money, realizes ambitions, present and future. $1.00 prepaid. Satisfac- tion guaranteed. Westgale, Plainview, Nebraska. 147

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FASCINATING business. Repair, adjust typewriters, adding machines. Learn easily at home from factory expert. Earn up to $15.00 daily. Com- plete instructions covering all makes $3.00 postpaid or sent C.O.D. Adding Machine Equipment Service, 3601 Michigan, Dept. 2042, Chicago. WE START you in business, furnish- ing Outfits and Instructions, operating “Specialty Candy Factory” home. Men and women, earn: $25.00 up to $60.00 weekly, all or spare time. (Our 29th year.) Booklet Free. W. Hillyer Rags- dale, Inc, Drawer 110, East Orange, MAN in Each Town to Plate Auto Parts, Reflectors, Bicycles, Fixtures, Mirrors, by late method. Simple plan of manufacturing at home starts You in Good Paying Business. Free par- ticulars and proofs. Gunmetal Co., Ave. A, Decatur, Illinois. MAKE Artificial marble, glazed tiles, uncanny. Tabletops, plaques, floors, hones, novelties. Hard, fireproof, in- expensive, cement secrets. Brilliant tile and liquid rubber samples 3c. ` John H. Payn, 945 Grande Vista Avenue, Los Angeles, Calif. LIKE To Write? Earn extra cash! Clipping and preparing newspaper articles for publishers. Simple, fasci- nating, profitable. Stamp brings details. Division 76, National Press, 3923 West Sixth. Los Angeles, California. COLOR Concrete Surface with chemi- cal solutions. Deautiful pottery with- out moulds. Garden wishing wells. Glazing concrete. Sample 10c. Holly- wood CementCraft. 8528 Wonderland, Hollywood, California. PROFIT with new products. Make, sell, repeat. Analysis. Research. Guar- anteed formulas. Biggest catalog free. Special prices, leads. Gibson J,abora- tory, Chemists, CE-1142 Sunnyside, Chicago. MRS. M. earned $267, three weeks, raising mushrooms in cellar! Excep- tional, but your eellar, shed perhaps suitable. We buy crops. Book free. United, 3848 Lincoln Ave., Dept. 86, Chicago. AFTERNOONS movies, free for outdoors, $340 month, home. Unique plan. No canvassing. Prepare for sur- prise, Folio-S, Station D, Ios Angeles. IF YOU have some spare room where you can do light work, see our offer on page 26. Metal Cast Products Co., 1696 Boston Road, New York City. SUCCEED With Your Products. Make- Sell Them. Formulas. Processes. Accurate analyses, Catalog free. A. Thaxly Co., Washington, D. C. FREE LITERATURE describes hun- dreds plans for making money locally or by mail. Gilbert Supply, 1107-M Broadway, New York. YOU'LL Like Resilvering Mirrors, Autoparts, Reflectors, Making Chipped Glass Signs. Write Sprinkle, Plater., 845, Marion, Indiana. ` PROFITS and pleasure making shell jewelry, novelties—Newest feld! Stamp appreciated. Challenge B-11, St. Petersburg, Fla. GET Cash Quickly, Steadily! — IIome business. Free booklet tells how. Century, 1261-M Broadway, New York. OPERATE a Collection-Credit Agency. Quickly learned. Big income assured. Write Cole Associates, Syracuse, N. Y. AGENTS—To mail our literature. Good profits. Home business. M. Maywood, 149 Fifth Ave., New York. SELL by Mail! Books, Novelties! Bar- gains! Big profits! Particulars Free! H. Elfco, 438 North Wells, Chicago. = Handy Shop Device The handy shop tool shown above is of great aid when cutting pipe or heavy cable, the material being placed on the special forked base and held tight by an adjustable clamp as shown. EARN cash income, copying and dupli- cating simple cartoons for advertisers. 3-N Service, Argyle, Wisconsin. WHERE To Buy At Lowest Wholesale Prices. Information free, Yorena, Box 312-A, Bayonne, N. J. HOW and where to obtain capital fully explained, free particulars. Star Service, Wapakoneta, Ohio. HOME Industries, 44 pages, year 10c. Melotz, Publisher, Benson, Nebr. CAMERAS & PHOTO SUPPLIES CAMERAS and supplies. Free illus- trated catalog listing everything photo- graphic—still and movie cameras, films, lenses—at tremendous savings. Hun- dreds of bargains, new and used. All guaranteed, We take your old camera or equipment in trade. Write now for your free copy of our newest money- saving bargain book—just out! Limited edition. Hurry! Central Camera Co., (Photographic Headquarters Since 1899), 230 South Wabash, Dept. 2-J, Chicago. MAKE money in photography. quickly at home. Learn Spare or full time. Easy plan. Previous experience un- necessary. — Common school education sufficient. Interesting booklet and re- quirements free. American School of Photography, 3601 Michigan Ave., Dept. 2049, Chicago. INCOME From your camera instead of expense, Low cost home course teaches you to make photographs for magazines, newspapers, advertisers. Tremendous demand, Earn good money wherever you live. Free book. Universal Photog- raphers, Dept. A, 10 West 33rd St., New York. MAKE MONEY Selling Snapshots— Dime brings hundred-page book com- plete instructions, buyers, real inform- ation, "Photomarkets", 402-M Evans Building, Washington, D. C. CHARTERS DELAWARE Charters: Complete in- corporating and organizing service $35. Submitted forms. Chas. G. Guyer, Inc., Wilmington, Delaware. CHEMISTRY CHEMICALS and Apparatus. Lead- ing school supply house offers Chemicals and Apparatus of professional quality at lowest school prices. Send 3c postage for Free illustrated catalogue and latest chemical price-list. New York Scientific Supply Co., Dent. 8— 111 E. 22nd St., New York City. BLACK Light Experimental Kit (Argon U. V. 5 fluorescent specimens) $1.00. Radium Spinthari- scope—$2.00. Slide Rules, Standard Type, 5 scale, 8 inches—30c. i prepaid. Catalog 10c—free with order. Laboratory Specialties Co., 130 S. Wabash St., Wabash, Indiana. FREE PLANS for inexpensive natural gas generator, New Style Bunsen Burner for natural gas, developes up to 2000? F., stays lit! $1.00 postpaid. Angelus Mfg. Co., Box 885, San Angelo, Texas. COAL SAVER A POSITIVE Coal Saver. Instruc- tions 25c coin. H. Pedersen, 1635 No. Mozart St., Chicago, Ill. CORRESPONDENCE COURSES 500,000 USED Technical and business hooks. Sold, rented, exchanged. AIL subjects. Satisfaction guaranteed. Cash paid for used books. Complete details and: illustrated bargain catalog free Send name. Nelson Co., 3225 Masna- hattan Bldg., Chicago. DETECTIVES DETECTIVES. Make Secret Investi- gations. Experience unnecessary, De- tective Particulars free. Write, George Wagner, 2640-V Broadway, N. Y. DRAFTSMEN DRAFTSMEN, Students. showcard writers save time with patented Uni- Does versal Drawing Instrument. free. wonders. Descriptive cireulars Box 451. Leominster, Mass. EDUCATIONAL & INSTRUCTION GET YOURSELF A 1938 GOVERN- MENT JOB. Start $105 - $175 month. Dependable. Men — women. Prep immediately. Common education. Ex- perience usually unnecessary. Fall particulars — list positions, FREE. Write today. Franklin Institute, Devt. M59, Rochester, N. Y. MEN Wanted—Learn Tool Making. Automatic Screw Mach. Machinist Trade. Big Demand. Actual Experience. Expert Supervision. Write for Free Book "M". Allied Screw Machine Co., Inc., School Div., 603-9 Lake St. Chicago. WANTED Immediately, Men-Wemen, age 18-50, qualify for Government Posi- tions. Commence $105-$175 morth. Common education sufficient. Valuable information free. Write, Instruction Service, 234, St. Louis, Mo. YOUR PROBLEMS — Electrical, Paint, Mechanical, Chemical, Automo- tive, Models, your invention, Boats, etc. Enclose $1.00 with question. Freeman, 314 Hawthorne Avenue, Yonkers, N. Y. ELECTRICAL EXPERIMENTS ELECTRICAL Kit, $1.69! light mile range. Arc furnace. Melt glass, metal. Weld iron. brass. Sun- tan rays. Dozens others. Complete with goggles, full instructions. Works from house light current. Electrical Salvage Co., Box 524-0, Linco ELECTRICAL SUPPLIES HUNDREDS of new, unu to-get electrical items, replaceme: and supplies. Send for tree wholesale Catalog. Autopower, 412 South Hoyne Ave., Chicago. EMPLOYMENT SERVICE EMPLOYMENT Guidance. Booklet. Successful Job Hunting. 25c coin. Employment Counsellors, Box 1283B, Milwaukee, Wisconsin. Make arc Nehr. 48 Accept No Substitutes! Always Insist on the Advertised Brand?

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ENGINES, MOTORS, ETC. WINDING Data, 225 motors, single ard three phase. Price $1.00. Motor Data Service, Box 7631, Kansas City, o. 2 FARMS 40 ACRES, Near White River, un- improved; poultry land. $175, $5 down, $5 monthly. Free list and literature. Hubhard, 224 Grossman Bldg., Kansas City, Kansas. FOR INVENTORS PATENTS—Before too heavy an out- Jay of time or money is made on an invention, a search of the Patent Office records should be made to determine as nearly as possible whether or not the same idea has been patented before. The cost of this search is small, while ihe value of the facts it uncovers is often considerable. We offer inventors and manufactors a thorough, prompt, confidential search service—plus ex- perienced counsel and assistance in every phase of Patent and Trade- Mark practice. Write for our new free book containing valuable information relating to patent procedure. Clarence A. O’Brien and Hyman Berman, Regis- tered Patent Attorneys, 28-R Adams Bldg. Washington, D. C. PATENT Your Idea. Write diately for two free books, Protection" and “When and How to Sell an Invention.” Fully explain many interesting points to inventors and illustrate important mechanical principles. With books we also send “Evidence of Invention” form. Prompt service, reasonable fees, thirty-nine years’ experience. Avoid risk of delay. Address: Victor J. Evans & Co., Registered Patent Attorneys. 42-B Vic- tor Building. Washington, D. C. WE SUCCESSFULLY SELL inven- tions, patented and unpatented. Write for proof, and tell us what ycu have for sale. Chartered Institute of American Inventors. Dent. 5-B. Washineton. D. C. INVENTORS: Send for my free 72- page book, Conscientious, prompt per- sonal service on all patent matters. Registered Patent Attorney. Randolph, Dept. 341. Washing WE LOCATE Buyers meritorious patented, unpatented inventions. If will sell write immediately to Invention Reporter, B-11236 South Fairfield, Chicago. Copyrighted booklet on request. FORMULAS, PLANS, ETC. ANALYSIS. Research. Newest guar- anteed formulas. Biggest catalog free. Special prices, leads. Gibson Labora- tory, Chemists, CE-1142 Sunnyside, Chicago. SUCCEED With Yeur Products. Make- Sell Them. Form: Preces Accurate analyses. Thaxly Co., Washington. D. C. NEW! Cheap, Safe, Non-in Dry Cleaning Fluid. Formu (Coin). Chemical Service, 304; 49th Avenue. Cicero, III, FORMULAS—AII kinds. Catalog Free. Illinois. mable DNE IG South All k Guaranteed. Kemico, 67, Parkridge, HYPNOTISM HYPNOTISM. Complete 20 Method Course 25c. Lonk Institute Hypnotism, MM-2984 North Ridgeway, Chicago. HYPNOTISM. Many methods ex- plained. Complete course $1. DeSala, Buechel, Ky. When Answering Advertisements Please Mention February Modern Mechanix Ca zalog free. A. | Paint Can Device Suspends Brushes Available in sizes to fit any paint can, new brush holders are designed to snap on the cans and hold the brush sus- pended over the can proper, eliminat- ing the dripping of paint and keeping the brushes free from dirt and lint. INVENTIONS INVENTORS: Write today for free book clearly explaining how to obtain patent protection by paying only Gov- ernment filing fee. American Patents Corporation, Dept. 5-E, Washington, INVENTIONS WANTED SMALL inventions wanted by manu- facturers. I'll help you sell your in- vention. Write for íree circular. S. d 7829-L, Euclid Avenue, Cleveland, hio. INVENTIONS Commercialized. Pat- ented or unpatented. Write Adam Fisher Co., 582 Enright, St. Louis, Mo. LEARN AUCTIONEERING No TALK yourself into big money. N other profession offers so much for so little. It requires little or no capital. Write The Old Auction House, Box 1526, Los Angeles, Calif. MAGIC TRICKS & NOVELTIES FREE! Magic Catalog 500 Tricks. Amaze, Mystify friends. Write today! Lyle Douglas, Station A-3, Dallas, Texas, SNAPPY Photos, Books, Novelties, Catalogue 10c. XE. G. Specialties, Dept. MM. 23 Glenn Ave., Carnegie, Pa. WE SUPPLY every noted magician. Large Professional catalog 25c. Holden, 222 West 42nd St., New York. MALE HELP WANTED LOCAL AGENTS Wanted to Wear and demonstrate Free Suits to friends. No canvassing. Up to $12 in a day easy. Experience unnecessary, Val- uable demonstrating equipment, actual samples Free. H. J. Graves, Pres., 1300 Harrison, Dept. B-819, Chicago. INTRODUCE new advertising idea to retailers. Show them how to Give cay Free Chewing Gum and increase prcfits! Send for big-commission plan Free Sample Outfit. National Adgum, Devt. L-25, Cincinnati, O. MALE—INSTRUCTIAN DETECTIVES. Work home or travel. Experience unnecessary. Write, Ameri- can Detective Institute, 2640-T Broad- way, N. Y. | MODEL Railroad Supplies j projector $11.89. MIDGET AUTOMOBILES BUILD a Midget Miller Racer. Com- plete plans for constructing this authen- tic midget automobile appear in the new 1938 edition of How-To-Build-It along with many other interesting home and workshop plans. Send 50c for this 148- page book to Modern Mechanix Publ. Co., Greenwich, Conn. MIDGETS! Motors! new; sport, racing. Over 20 midgets, 60 motors, $5.00 up. Latest lists, 20c. pps Midgets, Box 543-B, Zanesville, hio. Parts! Used, MISCELLANEOUS FOLLOW Thrilling News Of Daring Auto Racing Drivers In National Pic- torial Newspaper. 52 Issues $2.00. R. C. Kenney, 2895 Grand Concourse, Bronx, N. Y. PHONOGRAPH records slightly used, package 10 for $1.00, 25 for $2.00, no two alike. Plaza Music Co., Charlotte, N. C. BURIED TREASURE, Minerals, free booklet, photographs. Fisher, Palmer Bldg., Hollywood. WHERE To Buy or Sell Any Article. Send 10c. Warfield, 482 Winneconna, Chicago. MODEL ENGINES LOCOMOTIVE Electric. Steam. Gas engines, Castings Supplies. 25c. Latest Catalogue, usual refund. Emco, J-2417 N. Ashland, Chicago. MODEL RAILROADING BUILD a Model Railroad in 00 gauge (34 inch between rails). A complete catalogue of parts, construction kits, and completed units, One Dime. Nason Railways, P. O. Box 9, Mt. Vernon, Y., Dept. 2X. “OF Gauge (14” scale—1V4" between rails) Freight Car Body Kits $1.00, Illus- trated Catalog 10e. Westbrook Co., Hasbrouck Heights, New Jersey. MODELS & MODEL SUPPLIES YOUR Ideas developed into practical working model. 30 years successful experience; thousands satisfied custom- ers. Confidential service guaranteed, Bank references. Send 3c postage for 32 page book “Making Inventions, Pay." Crescent Tool Company, Dept. T. Cin- cinnati, Ohio, ENGINE Catalog 20c. Particulars free. Evraymesco, 28 N. Clinton, Chicago. MOTION PICTURE EQUIPMENT & ACCESSORIES GUARANTEED Mogull’s 100', fresh, 16mm film for Camera, $2.39 including processing. Tripod or screen carrying case 98c. 100% Safety cement 25c. Humidifier 25e, RCA Victor Sonnd- film 16mm, complete outfit $149.50, Keystone motor driven 400’ capacity Ampro 400 watt projector $61.50. Eastman 8 or 16mm projectors $18.00. Eastman 16mm movie camera $14.75. Projector floor stand $7.49. 1600 ft. reel $1.45. Save hy buying direct from Mogull’s, New York. 35mm Silver Jubilee Bargainst Silent, shorts, features, complete with title, ending, $1.00 per 1000’. DeVry Portable Silent Projector, 500 watt, motor-driven (suitcase) $29.50. DeVry 1000’ capacity, 1000 watt sound-on-film projector, Amplifier, speaker, tubes, complete ready for show, $198.50, fully guaranteed, 16mm silent, sound shorts, features for sale. | 8-l6mm library. Leica F3.5 Camera $45.00, Zeiss Iligh Power Binoculars, $29.00. House cf Satisfaction, Mogull’s, 1944-M, Boston Road, New York. 149

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— ed 21. 0070 ALS Binocular Microscope Aids Jewelers A new binocular microscope fitted with a mechanical stage bearing a new type of chuck block vpon which mounted stones may be fitted and orient-d in any direction for examination by trans- mitted light is seid to be of great aid to jewelers. (Bausch & Lomb photo.) MOTION PICTURE & SOUND EQUIPMENT LEARN Motion Picture Theatre Busi- ness. Home-Study Training: Manage- ment, Advertising, Projection. Free Catalog. Theatre Institute, 345 Wash- ington St., Elmira, N. Y. 16MM MOVIE titles to order. 2c per word. Minimum order 23c, Woifim, 6858S Stoney Island, Chicago. MOTORCYCLES RECONDITIONED Moter —-used parts fcr ail makes. Authorized Harley-Davidson Dealer. Whitman Motoreycle & Supply Co., 405.9 South- west Blvd., Kansas City, Mo. “cles. New SEND 15c for illustrated used Motor- cycle catalog. Bargains. Largest stock genuine Indian parts and motorcycles. Tudian Motorcycle Sales, Kansas City, ilo. OFFICE EQUIPMENT TYPEWRITERS, multigraphs, address- dictapnones, Eu half, ing machines, adders, licators. sealers, folders. Save write Pruitt, 553 Pruitt Bldz., C OLD BOOKS WANTED WE PAY Up to $5,000 Each for Old Books—Also high cash prices for old magazines, letters, newspapers. A single school book, story book, old Bible, travel book, almanac, etc., that looks worthless may bring you $50, $100, or $500 in cash. Thousands wanted! Send 10c now for latest price list. American Book Mart, 140 S. Dearborn, Dept. 730, Chicago. OLD GOLD WANTED HIGHEST Prices for Old Gold, Teeth, Watches, Jewelry. 100% full cash value mailed day shipment received. Satis- faction guaranteed or articles cheerfully returned. Information free. or ship today. Chicago Gold Smelting Company, 300-C Champlain Bldg., Chicago. 150 j PATENTS., Accept No Substitutes! PATENTS—Before too heavy an out- lay of time or money is made on an invention, a search of the Patent Office records should be made to determine as nearly as possible whether or not the same idea has been patented before. The cost of this search is small, while the value of the facts it uncovers is often considerable, We offer inventors and manufactors a thorough, prompt, confidential search service— plus ex- perienced counsel and assistance in every phase of Patent and Trade-Mark practice. Write for our new free book containing valuable information relating to patent procedure. Clarence A. O’Brien and Hyman Berman, Regis- tered Patent Attorneys, 28-R Adams Bldg. Washington, D. C. PATENT Your Idea. diately Protection" Sell an Write imme- for two free books, "Patent and “When and How to Invention." Fully explain many interesting points to inventors and illustraté important mechanical principles. With books we also send "Lvidence of Invention" form. Prompt service, reasonable fees, thirty-nine years’ experience. Avoid risk of delay. Address: Victor J. Evans & Co., Registered Patent Attorneys, 41-B Vic- tor Building, Washington, D. C. "INVENTOR'S Guidebook" containing 96 mechanical movements and advice about patenting, selling inventions, alo "Record of Invention", Free. Frank A. Ledermann, Patent Attorney-Engineer, 134 Nassau Street, New York. PATENTS INVENTORS— Time | counts — Don't risk delay in patenting your invention. Write for new 48-Page Free booklet, “Patent Guide for the Inventor." No charge for preliminary information. Clarence A. O'Brien and Hyman Ber- man, Registered Patent Attorneys, 28-8 -\dams Building, Washington, D. C. Booklet iree. Highest references. Best results. Reasonable rees, Watson E. Coleman, Victor Build- ing, Washington, D. C INVENTIONS Commercialized. Pat- ented or unpatented. Write Adam Fisher Co., 582 Enright, St. Louis, Mo. GET Your Own Patents. Legal blanks, complete instructions $1. Cudding Sons, Campbell, California. PHOTO DEVELOPING DEVELOP and print your own pic- tures. Save time, money with our complete outfit, $1.95 plus postage, or sent C.O.D. Includes electric ruby lamp, printing frame, photo paper, chemicals and equipment. One of hun- dreds of amazing bargains in our free, newest, money-saving bargain book. Send for it today! Central Camera Co., 230 So. Wabash, Dept. 22-], Chicago. FINER Finishing. Rolls developed and printed, with One Colored enlargement, or two professional enlargements. All for 25¢ (coin), Genuine, Known, Moentone Supefior Quality. Moen Photo Service, La Crosse. Wis. AT LAST! All. your prints in natural color. Amazingly beautiful. Roll de- veloped, 8 natural color prints, 25c. Reprints, 3c. Fast service. Natural Color Photo, C-39, Janesville, Wis. ROLLS DEVELOPED—Two Beauti- ful Double Weight Professional En- largements, 8 Never Fade Prints, 25c. Century Photo Service, LaCrosse, Wis. ROLLS DEVELOPED-—25c coin. "Two 5x7 Double Weight Professional Fulargements, 8 gloss prints. Club Photo Service, LaCrosse. Wis. LARJARGRAPH Reprints: Five (5x7 Enlargements) 25c. Cardinal Photo, Summit, N. J. Nationally . Aluminum Piping Cuts Installation Costs A specially designed aluminum pipe which will resist severe twisting, bend- ing and other strains saves consider- able time and expense in making gas stove installations. ü POULTRY MABE Money with poultry. Read America's biggest poultry magazine. Learn how leading poultry raisers suc- ceed. Only poultry magazine operating its own experimental farm. Three years $1.00, 9 months trial 25c. Poultry Tribune, Dept. C-92, Mount Morris, Ill. RADIO PLANS 18 Distance Crystal Sets— SW record 4,250 miles, with ^Radio- builder" —year—25c. Laboratories, 151-K Liberty, San Francisco. ———————— aE RADIO & TELEGRAPHY RADIO BUILDERS’ MANUA book of radio set building pl kinks for the home per Everything from a crystal powerful 6-tube auto radio Price 50 cents—order Modern Mechanix Ps : Fawcett Bldg., Greenwich. Conn. RADIO Engineering. broadcasting, aviation and police radio. Servicing, Marine and Morse Telegraphy taught thoroughly. All expenses low. Catalog free. Dodge’s Institute, King St., Val- paraiso, Ind. RAZOR BLADES 100 DOUBLE-EDGE Razor Blades $1 Postpaid. Myco-Pax, 1318 E. Pass yunk, Philadelphia. SALESMEN WANTED GOLD Reflecting Window Sign Let- ters. Penny Each. Large Sizes, Easily Applied. New Styles. Absolutely Beautiful. Free Samples. Atlas Sign Works, 7941G Halsted, Chicago, Ill. WANTED County Distributors. Ex- cellent opportunity for earnings. Na- tionally advertised product, Large company. Dept. 253, Fyr-Fyter Com- pany, Dayton, Ohio. SELL celluloid and_cardboard pricing tickets, Steel Shelf Moulding, Change- able Signs, Menu Covers. Every Store prospect. T. Pricing Press, 124 White Street, New York. Always Insist on the Advertised Brand!

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Gloves Clean Hands rubber gloves, Crepe vacuum effect when used with soap in washing the hands, are said to massage grease and oil out of the skin, leaving producing a the hands soft and clean. The gloves are especially designed for use by mechanics and shopmen. SPECTROSCOPES SPECTROSCOPE with book of 120 experiments, $2.50. Cudding Sons, Campbell, California. TAXIDERMIC SUPPLIES FREE new 32-page catalog. Eyes, tools, etc. Taxidermic Manufacturers Co., Memphis, Tenn. TELESCOPES, MICROSCOPES, ETC. ASTRONOMICAL Telescopes, Parts and Kits, Make one this winter. Write for folder. New Telescope Com- pany, 3675 West 165th Street, Cleve- land, Ohio. TELESCOPES, Microscopes, Binocu- lars. Lowest prices. Optical catalog free. Brownscope Company, 5 West 27th Street, New York. FREE Instructions! Make_powerful telescope in one evening! Very low cost! Atemsco, Box 213M, Flushing, LOWEST Prices en telescopes, binocu- lars, microscopes. Free Catalog. Hobby Man, State Street, Jefferson, Iowa. TELESCOPES, Microscopes, Binocu- lars, Mineralogy, Chemistry. Catalog free. Teeko, Evanston, Illinois. BUILD Reflecting telescopes; catalog free. Instructions 10c. Optical Labo- ratories, Larchmont, N. Y. VIOLET RAY LAMP ULTRA Violet—Infra Red. Dual Ray Health Lamp. Two separate units in one. Promotes Sun Tan—Vitamin “D.” Automatic control. AC-DC current. $3.90 postpaid. Details Free, Beyer Mfg. Co., 4515-M Cottage Grove, Chi- cago. WELDING DODGE Arc-Welder. Build your own 40 volts, 25-200 amperes direct current from old Northeast Dodge 12 volt auto- mobile generators. 120 amperes from i one generator, using % inch electrodes. ! 200 amperes, jt electrodes from two generators, etc. Low cost and upkeep. Results guaranteed. Certified Instruc- tive Plans $1.00. COD $1.12. Air mail 12c extra, Welders Club of America, B-3432 Merchandise Mart, Chicago. "MAKE Band Saw from old Auto Parts"; “How to make 15-100 ampere A.C. Arc Welder"; “How to build a real, lathe.” Complete drawings, plans, constructional details, 20c each. All three for 50c. Federal, Box 344, Dept. 23, Indianapolis, Ind. WELDING & SOLDERING 73-125 AMPERE are welder from Dodge generator. Complete plans and valuable catalog 35c. 50 other generator changés. LeJay Manufacturing, 214 LeJay Bldg. Minneapolis, Minn. First World's Fair Building Completed Main entrance of the newly completed $900,000 Administration Building of the New York World's Fair of 1939, at Flushing Meadow, Queens, showing sculptured figure of woman lifting veil from the World of Tomorrow. The panel is the work of Albert Stewart. The "nerve centre” of the fair is just 18 minutes by rail from the heart of Manhattan. It was completed in the record time of 124 days. The working forces of the $125,000,000 exposition are housed in the structure, which is ait conditioned, scientifically designed and modern in every respect. WIND DRIVEN PLANTS GENERATOR propellers, expertly de» sigued, factory prices. Universal Aire craft, Fort Worth, Texas. WIND ELECTRIC PLANTS BUIT,D wind light plant. We show you how. Complete plans and valuable catalog 10c. Wind plant parts, welders, electric fences. LeJay Mfg., 614 LeJay Bidg., Minneapolis, Minn. ADLETS FOR HOBBYISTS (Sea regular classified sectlon for rates and other Information.) STAMPS SUPER-WONDER Packet offered, containing 60 different stamps from Afghanistan, Transjordania, North Borneo, Marchukuo, Sudan, Macao, Iraq, Charkhari, French and British Colonies, including natives, beasts, ships, etc., all for 5c to approval applicants. Big illustrated lists included. Kent Stamp Company, Box 87-Z (G. P. O.), Brooklyn, N. Y. STAMP Annual Free—Special Coronation Edition—De- scribes and illustrates Albums, Supplies, United States, British Colonial, Coronation and foreign stamps. This fifty- page catalogue Free. Gray Stamp Company, Dept. MM., Toronto. Canada. BHOPAL—India’s Only Triangle! Giant, hicolored obsolete! With Colossal Economy Packet including thirty attractive pictorials—10c with low-priced approvals. Economy Stamps, Box M1543, Hartford, (1) Connecticut. DIAMOND Airpost Commemorative Issue Complete, Pro- letariat Portraits Complete, Dragon Stamp, with 117 addi- tional, cataloging $3.00, only 10c. Friendly Filatelists, Box 4428M, Philadelphia, Penna. DIAMOND Shaped Airmail Set, New Panama issue, Japanese New Year, Plus thirty attractive pictorials—10c with Double Premium Approvals. Tru-Value, Box M1412, Hartford, (3) Connecticut. PRODIGIOUS GIFT! German State, Selangor, Perak, Negri Sembilan, Bicolored Banana Airmail, Siberia—Free with Approvals! Postage 3c. Saxon Company, 3 DeKalb Ave., Brooklyn, N. Y. When Answering Advertisements Please Mention February Modern Mechanix FREE—Rare Diamond Shaped Airmails provided you pur- chase at least 25c from our double premium approvals, Progress Stamp Service, Kirkland, Washington. GIGANTIC Bhopal Trinage, Turks Caicos, $5. U. S. Caymans, genuine Baden. Everything 3c with approvals. Viking, 1-MM Hanson Place, Brooklyn, N. Y STAMPS! 100 diff. 3c; 500 diff. 35c; 1,000 diff. 90ct Illustrated Album (4000 spaces) 22c. Approvals sent. Tatham Stamp Co. (D9) Springfield, Mass. UNITED STATES—45 different 10c. Free 25 different with approvals. Enclose 3c. Sidenburg, Baroda, Mich. FREE!!! New King George Set. 901T Fourth, Baycity, Michigan. AUTOMOBILE PHOTOS PHOTOGRAPHS, World's finest, fastest, costliest auto» mobiles. Hispano, Duesenberg, Mercedes, Bentley, ete, 12 for $1.00. International, Box 329, St. Cloud, Minn, OLD STAMPS & ENVELOPES WANTED Postage 3c. Roberts, WILL PAY $200.00 for 1911 Vinfiz stamp. $85.00 to $1,000.00 for certain 1924 stamp. Send 5c for Large Illustrated Folder showing Amazing prices paid, Vernon Baker, 444-MM-11, Elyria, Ohio. 151

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Less Motor Drive No. 415-YA, 014" swing by 3” bed Workshop Bench Lathe with Horizontal Motor Drive, 14 H.P. Reversing Motor, Switch and Adjustable Belt Tension $117.00 Countershaft . . ($15.00 down, $6.00 a month for 18 months.) THE new 9-inch Workshop Precision Lathe is a back-geared, Screw Cutting Lathe, and has the same workmanship and materials as our larger, more expensive models, It ig designed to handle the finest, most accurate jobs in manufacturing—in the tool room, in home workshops and automotive machine shops. This lathe at 885 and up repre- sents the greatest value we have ever offered in 31 years of fine lathe building. Features include Twin Gear Reverse to lead ecrew, Ball Thrust Bearing on Spindle, Automatic Longitudinal Screw Feed to Carriage, Precision Lead Screw for Cutting screw threads from 4 to 40 per inch, 34-inch hole through spindle taking collets up to 14-inch capacity. Takes 38 attachmente Lathes Stocked in Principal Cities Chicago, 11l.—C. B. Burne Mchry. Co., 541 W. Wash. Blvd. New York, N. Y.—A. C. Colby Mchry. Co., 183 Centre St. Philadelphia, Pa.—W. B. Rapp Mehry., 132 No. Third St. Los Angeles, Cal.—Eccles & Davies Mchry., 1910 Santa Fe Detroit, Michigan—Lee Mchry. Co., 6318 E. Jefferson Ave. Milwaukee, Wisconsin—Voell Mchry. Co., 1533 No. 16th St. Boston, Mass.—The MacKenzie Mchry. Co., 36 Oliver St. Cleveland, O.—Reynolds Mchry. Co., 2034 E. 22nd Street. . Waite FOR THESE BOOKS “How to Run a Lathe” has 160 pages with over 300 illustrations of work on a lathe. Over 1,500,000 copies sold. 25e each. Cata- log No, 15-Y describes and prices the 9” Workshop Lathe in: 8 drives and 4 bed lengths. Copy sent free, postpaid. South Bend Lathe Works 264 E. Madison St., So. Bend, Ind.,U.S.A. * South Bend Lathe Works, 284 E. Madison St., South Bend, Ind., U. S. A. Please send me the foll lowing: D) No. 33LB “How to Run a Lathe,” 25¢ D] No. 15Y 9” Workshop Catalog, Free Easy Payment Purchase Plan Class of Work. ........ Nimes oracio eo dew cue ERES nd Reale esu 152 Accept No Substitutes! A Back-Geared Screw- Cutting Precision Lathe Weight 320 Ib: for milling, grinding, draw-in Collet chuck work, and many other lathe operations. In 3’, 314’, 4’, and 434 bed lengths. Write for information on this lathe and larger sizes in motor drive and countershaft drive. Get the bulletins we offer— with instruction about Manufacturing work, Automctive jobs, Home shop projects, etc. Use coupon below, 5 OTHER SIZES: 9", 11", 13", 15" and 16" SWING IN ALL BED LENGTHS—PRICED $102 to $1500. Lathe shown below is No. 117-C, 16” x 6' Quick Change Gear Underneath Belt Motor Driven Lathe with $969 1 H.P. motor. Complete as shown, Wt. 2300 Ibs. ($97 down, $43.50 monthly for 22 months.) “SOUTH BEND (Pzecéscon LATHES: Always Insist on the Advertised Brand?

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START AT HOME Here's your chance—a money-making business of your own. 'furn potatoes Into cash by making new kind of Po- tato Chips with my improved outfit. Makes delicious, superior, '"NON- GREASY'' Chips at low cost. A few hours practice does it. Begin any- where—city, Village, town. “Potatoes cheap and plentiful, Wholesale or re- tail. Steady year 'round business. Groceries, markets, restaurants. tavans do the retailing for you, WE HELP START YOU IN BUSINESS Great quantities of Chips are eaten daily. Profit large—unusually so. You can start this money-making business on a ‘next to nothing’? outlay of cash. Write for Potato Chip Booklet. LONG-EAKINS CO,, 242-S High St., Springfleld, Ohio. a ERERTÍOES BIG PAY GOOD FUTURE are interested in working yourseif Into a Hw pala position in Aviation under our Appren- tice-Plan—Write, immediately, anclosing stamp— MECHANIX UNIVERSAL AVIATION SERVICE CO. Dept, A2 Detroit, Mich. Haven’t you often driven the wrong road | and had to backtrack many miles? The Hull Streams line Auto Compass always shows your direc- tion of travel, prevents backtracking, saves money and time for only $2.95 at vour dealer. Two-piece model $1.95. Write for circular. HULL MFG. CO., P. O. Box 246-M9; WARREN, OHIO MAKEN N VANS NATING | ONLY Radio-Electrical $3 99 EXPERIMENTS federen 25 pieces genuine commercial apparatus with illustrated manual! Bulld radio circuits, 110-% volt motor. extenaion phone, thief detector. are light, are furnace, electric stove, generate ultra-violet rays, many more. SAVE 60% —Send only $3.99 for kit and 6 Radio-Electrical books (value over $10). Money back if not pleased. Order NOW! Box 524-62, ELECTRICAL SALVAGE CO., Lincoln, Nebr. SPECIAL Only ‘Corresp ondence Courses In’. RADIO and ELECTRICAL ENGINEERING b^ ELECTRICAL ENGINEERING Sot, food EP 25 of wide electri- cal. eld: gi apare yourself, at Low Cost, for secure future, Modern simplified anyone can understand quickly. RADIO ENGINEERING Extra fine course in radio, Public address; photo-electric work. Tr hs you be super-service man, real vacuum tube technician. xper! Sienta? kits furnished. Diploma given on completion, Tultlon, Sr $25, either course. Deferred payment plan avallable. E! Send name quick for free copies of school catalogs student magazines, complete detalls. SEND NOW. LINCOLN ENGINEERING SCHOOL, Box 931-63, Lincoln, Nebr. WILL YOU WEAR THIS SUIT and Make up to $12 in a Dey! Let me send you this flne all-wool tailored suit FREE OF COST. Just follow my easy plan and show the suit to your friends. Make up to $12 in a day easily. No experlence——no ganvassing necessary, Send for Samples—FREE OF CO Write today for FREE detalls, ACTUAL Se LES and “sure UI getting plans. ene. no B eve ins, rogress failorin: Qa ep 509'S. Throop St. 9 Sor D'hicago, IM. When Answering Advertisements Please Mention February Modern Mechanix Start $1260 to $2100 a Year MANY 1938 APPOINTMENTS EXPECTED Railway Postal Clerks Railway Postal Clerks get $1,900 the first year regular, being paid on the first and fifteenth of each month. ($79.17 each pay day.) Their pay is automatically increased yearly to $2,430. Advance may be had to Chief Clerk at $2,700 a year. ($112.50 each pay day.) 3 Days On—3 Days Off—Full Pay Railway Postal Clerks on long runs usually work 3 days and have 3 days off duty or in the same proportion. During this off duty their pay continues just as though they were working. They travel on a pass when on business. When they grow old, they are retired with a pension. City Mail Carrlers, Post Office Clerks Clerks and Carriers now get $1,700 the first year on regular and automatically increase $100 a year to $2,100 and $2,300. Customs Inspector Salary $2,100 to start. Men 23 to 45. "Work connected with examining baggage and merchandise entering the country from foreign parts covering boats, trains, roads, autornobiles, etc. Many Other Positions Many other positions are obtainable, » atl CUSTOMS Those wishing these positions should INSPECTOR qualify at once. Get Free List of Positions ol out the following coupon. "Tear 1t off and mail it today—now, at once, This investment may result in your getting a blg-paid govern- ment job. FRANKLIN INSTITUTE, Dept. L262, Rochester, N. Y. Rush to me, entirely free of charge (1) a full description of U. S. Government Jobs; (2) Free copy of illustrated 32-page book, ''IIow to Get a U. S. Government Job"; (3) List of U. S. Government Jobs; (4) Tell me what to do to qualify for a U. S. Government Job. Name eestooooseve Address ,.,..... » Use This Coupon Before You Mislay It. Write or Print Plainly. 153

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MM Short-Wave Transmitter [Continued from page 142] neutralizing condenser slightly until the bulb again goes out. Repeat this procedure until the bulb will not light when the amplifier tank condenser is turned from 0 to 180 degrees. A miliammeter in the grid circuit is a more accurate method of neutralizing than the flashlight bulb. If the stage is neutralized with a flashlight bulb for rough adjustment, turning the tank condenser may cause a slight movement of the indicator pointer of the grid milliammeter. If this occurs, turn the neutralizing condenser slightly, Turn the tank condenser again and watch the meter for needle movement. Continue to adjust the neutralizing condenser until C9 can be turned without having an affect on the meter. After the tube is neutralized as completely as possible, replace the positive high voltage lead removed before the neutralizing process was started, and turn on the power. Full voltage should not be applied to the amplifier until it is tuned to resonance and a dummy antenna is connected. When power is first applied, place the bleeder tap at a point where approximately 600-700 volts will be obtained. When the tank condenser is turned, the milliammeter will show a sharp drop when resonance is reached. If a flash- light bulb and loop of wire is used with the amplifier, do not hold it too close to the tank coil or the bulb will burn out. When the stage is tuned, connect a dummy antenna for final testing with full plate voltage. Do not use high voltage unless a load is provided for taking up the excess of r. f. power available, If full voltage is used when there is no dummy antenna connected, the tank or neutralizing condensers may arc over. When the set is operating in a satisfactory manner, listen in to its signal with a receiver or a monitor, If the receiver is located in the next room and the antenna and grcund disconnected, no difficulty should be experienced in tuning in a sharp signal. Of first importance on the subjcct of testing this or any other transmitter: DO NOT TEST WITH AN ANTENNA COXNECTED. On-the-air testing is nuisance number one to any listener. Always use the dummy load for this purpose. The results eltained are just as good as with the antenna, and it does not clutter up the air with unnecessary signals. With approximately 400 volts on the slate of the 6L6, the grid meter should show approximately 18 milliamperes. The plate milliammeter should indicate between 40 to 60 milliamperes under load. The T55 can be loaded to draw not more than 150 milliamperes. With approximately 1.200 volts on the plate, the output will he about 140 watts, assuming that the stage is operating at 75 per cent efficiency. Under no-load conditions, the builder may notice that the tank coil becomes quite warm. However, when a load is applied, this condition almost entirely disappears. In crowded neighborhoods, probably the greatest potential source of trouble with nearby receivers is that cf ‘tkey click.” This usually can be eliminated Ly installing a “key clip filter.” Several suitable types will be found in the "Radio Amateur’s Handbook.” The builder will find tuning considerably more satisfactory if insulating flexible couplers are attached to each condenser tuning shaft and the dials attached to insulating rods. This completely eliminates any possible body capacity affect and also the danger of shocks or burns. Although the power supply is capable of causing severe and sometimes dangerous shocks if touched -accidentally, the condensers alsc cause severe burns. Serious shocks from this source alse are pessible, i. e. one hand on the grounded chasis and the other touching the rotor of the condenser. When an antenna is connected, the amplifier plate current should rise from four to six times its minimum reading. Never lcad the amplifier tube to the point where its plate shows color, that is, a red tint. Although the input may inm ie plenty of output, the tube life will be exceedingly short. When turning on the transmitter, always permit the filaments to burn a minute or two before plate power is applied. This holds true particularly for the 866's and the T55. Although only one power supply diagram is shown, a suitable supply for the oscillator is described on page 102 of the December issue of Mopers Mecuanrx. If the builder prefers to use the 1,200-volt supply for both stages, the 400-volt tap shown in dotted lines in the diagram should be connected to the 400-volt connection at the sct. When separate power supplies are used, the negative terminals should be connected together. Separate supplies are recom- mended because they give the oscillator more complete isola- tion from the succeeding stages. Coil dimensions for the 80-meter hand are as follows: L4—27 turns No. 20 D. S. C. wound to cover leugth of one and one-half inches. L5—26 turns No. 16 D. C. C. close wound. L6—26 turns No. 14 enamel wound to ccver a five-inch space. 154 Flying The Subway Express [Continued from page 140] figure bent on self-destruction may leap to the tracks. The motorman hasn't a chance on earth of stopping his train within two car lengths, even with full air power applied. Every few weeks somebody elects this form of suicide. They do not always succeed, for in busy stations a deep trough is cut between the tracks and many persons have landed in it while the train passed over them harmlessly. But the jumper is the black dread of the motorman. There is nothing he can do about it. The law of averages makes it certain that sooner or later a suicide will select his train to end his life. When the event occurs, the motorman finishes his run, just as an airplane pilot goes up immediately after a crash. The subway must go on. Oddly encugh, the motorman is the one man a suhway passenger almost never sees. Often he does see the guard who controls the electropneumatic car doors. But as he tools his string of heavy steel cars through the tunnel, the motor- man himself is watched. Like the towers erected along surface railroads, the subway has its control stations at express stops where miniature tracks of the subway section show the movement of trains. k As each train moves along it actuates colored lights which flicker on along the toy tracks to show its progress, At any time the towerman knows the exact position of trains in his section, and he hands out orders in event of emergency. For a single five-cent investment you can ride the subway as Jeng as life remains in you, and life itself can be sustained at the confection stands and lunch counters which will be found inside the turnstiles and at the route terminals. You can telephone, buy magazines, newspapers, flowers, go to theatres and enter shops and department stores, all without going aboveground. . Subway rolling stock, driven constantly at top speed, is regularly inspected and goes to the shops for periodic over- hauls. Much repair work can be done by simply rolling the cars over pits and working from beneath, but just as often it is necessary to lift the massive steel body entirely off its trucks. This is done by 25-ton steel cranes which lift off the body and set it on jacks while the wheels are rolled inte the truck shops. Usually repairs are made and the car put back into service within twenty-four hours, Cars in tke shops earn no nickels, and the I.R.T. must keep 2,118 cars in daily operation, the Independent subway, 1,162. The average run of a motorman is 100 miles a day. For the motorman, of course, his run is work, but he derives from it the satisfaction which comes to any railroad man. In many respects the job of the subway trainman is more complex than that of the engineer of a crack trans- ecntinental flyer, and in a single day he carries more passen- gers that the flyer does in a year. For the passenger who gets up in the nose of the first car, lets the breeze tear through his hair and watches the tunnel unrojl its light-spattered mysteries, a ride on the subway scenic railway is one of the most thrilling experienecs of the big city. Defective Welds Detected By "Magnetic Eye" A “magnetic eve" which can see into metals and detect welds has heen developed by Professor W. B. Kouwenhoven of Johns Hopkins University and A. E. Vivell of Princeton University. The "eye" is based on principles of magnetism. The welded seam is magnetized by a powerful alternating magnetomotive force. ` For welds less than one-quarter-inch thick, 60 cycle current insures penetration of the magnetic flux. Two search coils connected in opposition are placed on the seam so that any stray field which may he present cutis their windings. The shape of the wave of electromotive force induced in the coils is then observed by means of an oscillc- granb. i is claimed for conditioned air that it reduces the number cf heat prostrations in summer and the number of cclds in winter. A new apparatus for medical use makes it possible to transmit heart beats by wireless and to record them like a sraphonhone record. Germany has a reserve of lignite in the lower Rhine region estimated at fifteen billions of tons.

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THOUSANDS NOW PLAY who never thought they could! Learned Quickly at Home _ Makes Extra Money Wouldn't Take $1000 for Course I am delighted with the U. I have completed your wonderful method The lessons are so simple that anyone can Music course of instruction for Guitar, For the past year I have been understand them , I have learned to play by It is clear and thorough, made teaching and I have earned $200 thanks note in a little more than a month. I wonderful progress, N to the U. $. School of Music. wouldn't take a thousand dollars for my "E M Ga Nu. Gs *C. C., New Jersey course, *S. E. A., Kansas City, Mo. You, too can play any instrument By this EASY A-B-C Method OU think it's difficult to learn music? simple, A-B-C way. Now all over the That’s what thousands of others have world, enthusiastic music-lovers are en- thought! Just like you, they longed to joying the thriling satisfaction of creat- play some instrument—the piano, violin, ing their own music. They have found guitar, saxophone or other favorites. the key to good times, popularity and But they denied themselves the pleasure profit. —because they thought it took months and And that's what vou can do, right now. years of tedious study and practice to Simply mail the coupon below. Get the learn. d proof E oen you, too, can learn to play And then they made an amazing dis- your favorite instrument—quickly, easily. Surprised Friends. . covery! 'They learned about a wonderful in spare time at home. Never mind if I want to say that pr way to learn music at home—without a you have no musical knowledge, training are greatly surprised ifere JR- e oaie private teacher—without tedious study— or talent. Just read the fascinating il- ainerent piores ver happs "io and in a surprisingly short time. They lustrated booklet that answers all your have chosen your method of wrote to the U. S. School of Music for questions—examine the demonstration les- learning. the facts about this remarkable short-cut son. Both will be mailed to you without *B. F., Bronx, N. Y. method. And the facts opened their eyes! the slightest cost or obligation, Tear To cap the climax, a free Demonstration out the coupon now, before you turn the on actually showed them how easy it page. (Instrument supplied when need- to learn. ed, cash or credit.) U. S. School of e result? Over 700,000 men and Music, 2622 Brunswick Bldg., New York have studied music at home this City. Fortieth year, Established (1898). FREE DEMONSTRATION LESSON AND BOOKLET U. S. SCHOOL OF MUSIC 2622 Brunswick Bldg., New York City Wi t or obligation to me, please send me your free illustrated booklet and «demonstration lesson, d in the instrument checked below: PIANO BANJO TROMBONE VIOLIN MANDOLIN FLUTE QUITAR UNELE peoo ACCORDION Best Method by Far SAXOPHONE TRUMPET DRUMS AND TRAPS Enclosed is my last examina- CELLO HARP HARMONY AND COMPOSITION tion sheet for my course in HA WAILAN GUITAR CLARINET VOICE CULTURE Tenor Banjo. This completes my course, I have taken les- Have You sons before under teachers, but - This Instru.? my instructions with you were by NAs ao an oca Rec ROSA HA Suo pL I aisle Taxe woe o Lo aab Eua ERES BLEU sa ns far the best, . *A. O., Minn. POCHI NETTE V5 andes I a euis Ra caecos: A tid deg alana i P E aA Rod: EXTA S *Actual pupils’ pne ‘on SA quest, Pictures y professiona . * models; [o MER RR E RPHPOOPRO TU NUTS RR IE Stateuss. ecelesie RINTED iN DES

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E es] TE 1 is | C s Let me wish you MORE. PLEASURE Copyright 1938 Liccerr & MYERS ToBacco Co.

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uble Page Spreads

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3. E. SMITH Pres; N. R. i. Established 1914 The man wh has directed th ome stud men for Radio Ind than any o n in America. sting chief Operator Broadcas n Station quiis, T b dio Broadeast, one E! nd “immediately i joined eus NUN MPC, where Tam ed, So Mich. mpieted $10 a Week in Spare Time Work has consisted of R; adio ing, with some Public ess ems work—all in my Sip veek.”—WIL M T05 Ridge Road, CLAS ame Radio Man with stor ri qio man pr the Atlan m Head mi techn to your C m $200 to $300 a Month in Own Business “Vor the last 18 months I have | business for myself, making be. 0 $300 a month. I [| N. R, I to thank for my start in t n ARLIE J. FROEHNER, W. Texas Ave., Goose Creek, Texas, i tores serviceman for sb E 1 g h my y two 5 Alon duc worl ry from a hand eceive lam ce rate m paid STELLE Nu LEE ams Accept No Substitutes! Als ANY MAKE 50575 A WEEK | Will Train You at Home— mail coupon for FREE Book Do you want to make more money? Radio offers you many opportunities for well-paying spare time and full time jobs. You don't have to give up your present job, leave home or spend a lot of money to become a Radio Expert. Many Radio Experts Make $30, $50, $75 a Week Radio broadcasting stations employ engineers, operators, sta- tion managers and pay up to $5,000 a year. Spare time Radio set servicing pays as much as $200 to $500 a year—full time jobs with Radio jobbers, manufacturers and dealers as much as $30, $50, $75 a week, Many Radio Experts operate their n full time or part time Radio sales and se e businesses. s, inspectors, feremen, engineers, servicemen, paying up io $6,000 a year. Radio operators on ships get good pay, see the world besides. Automobile, police, aviation, commercial Radio, and loud speaker systems are newer fiells offering zood opportunities now and for the future. Television promises to open many good jobs soon. Men I trained have good jobs iu these branches of Radio. Read their letters in my 64-page book. Mail the coupon. There's a Real Future in Radio for Well-Trained Men Radio already gives good jobs to more than 300,000 people. And in 1936, Radio enjoyed one of its most prosperous years. More than $500, 000,000 worth of sets, tubes and parts were sold—an increase of more than 60% over 1935. Over a million Auto Radios were sold, a big increase over 1935. 24,000,000 homes now have one or more Radio sets, and more than 4,000,000 autos are Radio equipped. Every year millions of these sets go out of date and are replaced with newer models. More millions need servicing, new tubes, repairs, etc. A few hundred $30, $50, $75 a week jobs have grown to thousands in 20 years, And Radio is still a new industry—growing fast! Many Make $5, $10, $15 a Week Extra in Spare Time While Learning Almost every aS hborhood needs a good spare time service- man. The d. you enroll T start sending you Extra Money Job Sheets. They show you how to do Radio repair jobs, how to cash in quickly. Throughout your training I send you plans and ideas that have made good spare time money— from $200 to S300 a —for hundreds of fellows. I send you special Radio equipment and show you how to conduct experiments and build circuits which illustrate important Radio principles. My training gives you PRACTICAL EXPERIENCE while learning. vays Insist on the Advertised Brand? SET SERVICING, Spare time set servicing paye many $5, $10, S15 a week extra while learning. Full tlme servicing pays as much as $30, $50, $75 a week. BROADCAST. ING STATIONS. Employ munasc engineers, oper- ators, installation and maintenance mon for fascinating jobs and pay up to $5,000 a year. I Give You a Professional Servicing Instrument Here is the instrument every Radio expert needs and wants—an_All-Ware, All-Purpose, Set Servicing Instrument, 9^ Yt contains everything necessary 10 measure Ç. voltages and current; esistances adjust and align any set, old or new. It sat needs for professional serviclng after ate—can help you make extra money servicing sets while training. LOUD SPEAKER SYSTEMS. Buildings, installing, sereleinz and ting publie ad- systems is another growing field for men well trained in Radio, You Get a Money-Back Agreement I am sure I can traln you successfully, T agree in writing to refund every peuny you pay if you are not satisfied with my Lessons and Instruction service when xou finish, I'N send you a copy of this agreement with my Free Book, AUTOMOBILE RADIO, Another new Radio field—sclling, iu- stalling, servicing, Ona millon or more auto owners will install radio sets within the next year, ‘Book FREE Find Out What Rad o Offers You Act Today, Mall the coupoi free to any fellow over time and full time oppo al out aining in Rad meu I trained, telling what Radio offers YOU paste on a posteard—NOW! now for ows you letters from and earning. Find out MATE THE COUPON in an enrelope, or J. E. SMITH. Pres., National Radio Institute Dept, 88H ngton, National Radio Institute, Washington, D. C. Dear Mr. Smith: Without obligating me, send “Rich Rewards in Radio,” which points out the spare time and full time opportunities in Radio and explains your 50-50 method of training men at home in spare time to become Radio Experts. (Please Write Plainly.) NAME ADDRESS CITY . When Auswering Advertisements Please Mention February Modern Mechanix 7.

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How To Determine The Patentability Of Your Invention Before you spend money in making a model, or spend weeks in its design, we advise you first to have a preliminary search made through U. S. Patents in the U. S. Patent Office to see if there are inventions like yours already on record; and, if sc, let us give you our opinion as to the patent- ability of what vou have. experienced searchers to perform From the reports of our searchers we can quickly form our opinion as to whether your inv is conirented with ob- stacles in the form of already granted patents. First get our FREE BOOK and read the chapter on "How Can I Know Whether My Idea Is Patentable?" How We Serve The Inventor 7; peeraa every state in the Union, Our organization is a large and efficient one, Cur practice is con- fined entirely to Patents, Trade-Marks, and Copyrights. We have had years oi experience in Patent Matters. When you place your in- vention in our hands, we are in position to proceed at once to secure protection for vou. Our fees are reasonable, and, if you desire, we can arrange convenient terms of payment, We employ this service for you. oe Help is the Patent Attorney? Your invention may provide your life's great- est opportunity. If it is to bring income to you it should be legally yours. Upon your patent attor- ney's skill rests how completely vour patent covers all the protectable points in your invention. The inventor may actually lose money on his invention by overlooking a single claimable point that a skilled patent attorney would not miss. What The Inventor Must Know In order to pro- ceed successfully, the inventor must follow certain definite steps that precedent has established as the quickest way to reach his goal. Our FREE BOOK, "Patent Guide for the Inventor," gives a concrete logical, and thorough resume for the inventor to follow. It takes him, through 48 pages, from the crude first model to the finished commercial product. It shows the inventor how to avoid mistakes, how to shorten the road in getting his invention ready for market; it also points out how to save money and avoid the errors of inexperience in applying for patent. Getting our FREE BOOK should be the first step in definitely declaring yourself an inventor. 4 After you get this illustrated, clearly worded guide of care- fully compiled patent knowledge you will know how to pro- ceed without expensive mistakes and discouraging setbacks from “wrong-track” methods, BRIEN. CLARENCE A.0 3179 ADAMS BUILDING, WASHINGTON, D. c. Registered Patent Attorneys before U. S. Patent Office 8 Accept No Substitutes! Always Insist on the Advertised Brand! OF INVENTION FORM titra Ofte: vention Porm enables you to make in con- venlent form a sketch of your invention and have it wit- nessed in a manner of value to you should the occasion for evidence arise. MAIL THE COUPON TODAY and oblain our FREE BOOK and Record of Invention Form, Keen competition in every form of in- dustry has put manufacturers feverishly at work trying to speed up output, reduce overhead, save on materials, outsell trade opponents. The inventor is the key-man in making advancement possible to any business, Upon the inventor rests the success of many enterprises. This does not mean that you must have something gigantic to win commercial success. A new way to open a door or button up a shirt may be the very thing hundreds of manufacturers are looking for. If you have something novel —if it is practical to manufacture— no matter whether it be an improved rattle for a child or a whistle for a mechanical automobile, there is likely a wait- ing market, importance Of immediate Action In making application for pat- ent it is important to be first. Even if your application is de- layed by a few days you may be placed at a disadvantage. The short time that elapsed be- CLARENCE A. O'BRIEN | & HYMAN BERMAN iS 3179 Adams Building Washington, D. C. Registered Patent Attorneys Before U. S. Patent Office Please send me at once your Big Free 48-Page ook, "Patent Guide for the Inventor" and your TEAR OFF AND MAIL e now: S. . * 5 e Specially Prepared ‘‘Record of Invention'' form. tween Elisha Gray’s application 5 This request does not obllgate me. for his telephone patent and cT E EE the application of Alexander 4 Graham Bell probably cost EE. EENEI PEE cutn tds PER ENTERS Gray the rights to the tele- phone. When Answering Advertisements Please Mention February Modern Mechanix 9

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Since the ‘‘Horseless Buggy" Days, We Have Helped Inventors ERHAPS you have already heard about our firm, because one client tells another—and we have served men in every state in the Union, and in nearly every foreign country. We have been working with inventors since 1898. If you have a good inven- tion—or an idea for one—and don't know what Victor J. Evans & Co. can do for you, NOW is the time to find out. How We Can Help You Both the Patent Offce and the U. S. Supreme Court have made it clear that the inventor needs the assistance of a competent patent lawyer when it comes to protecting an invention. It is one thing to think up a good invention—it is another to get effective patent protection on it. For more than a third of a century —it has been our business to give sound advice and counsel to in- ventors. Our free books (described on the opposite page) tell what steps to take first, how to protect your- self, how the law protects you, what you must do, when to offer your in- vention for sale, how others have succeeded, and much more. You need this information. Have Excellent Com- mercial Possibilities REQUENTLY inventors confuse he size or the complication of a device with the question of commer- cial value and patentability. These two factors, of course, have no re- lation to each other. Most of our present-day complicated machines represent a process of evolution, a series of inventions. On the other hand, every so often some inventor comes along with a very simple "gadget" which possesses the ele- of broad utility and is patent- able. Scme of the most profitable in- ventions have been of this latter class. Shown above are a few such examples. Whether a device is simple or complex, ii it represents a forward Step to save manufacturing coste, to save labor, or to add enjoyment to human life, it may prove patentable and profitable. This subject is more fully discussell in the beoklet en- titled “Patent Protection” shown on the opposite page. DAYE SARNOFF, once a poor lad and now the famous President of ihe Radio Corporation of America, in an article in Liberty Magazine states: “Civilization means elimination of un- necessary labor. The sewing machine and the vacuum cleaner save millions of women from backbreaking toil. The tractor makes the farmer’s life bear- able. The automobile lends wings to us all The airplane is our magic carpet, It wouk be madness to slow up invention because our trouble is not that mechanical science moves too speedily, but that the governmental and social sciences move too slowly «++ In a world reorganized to vibrate within certain wave bands, human intelligence will be able to dis- tribute equitably nature’s houn- ties from above and below, ». and make princes of ,, paupers.” What Will Be Next? VER since George Washington signed the first patent, America has led the world in inventions, It may be said that not a year has gone by without some important inventions being patented and commercialized. David Sarnoff, president of the Radio Corporation of America, sees a big future ahead for science and inven- tion, Just as sure as the sunrise, 1938 will see new inventions come out— new wealth made from patents, Your idea may be one of them. You never can tell For this reason you should send for our books tocay and get the facts about patents and inventions. These FREE books tell you Get the answers to your questions: How can I protect my invention? When can I show my invention ta manufacturers? When can I offer it for sale? How should I go about selling it? Can I get protection witb- out a patent? What are my em- ployer's rights? These and other im- Portant questions are fully answered, Learn how our patent laws protect you The U. S$. has liberal pat ent laws, and much of our national wealth is based on pate ents. In fact, a Japanese com- mission ^ decided that American progress was mainly due to our patent laws. These laws are made to protect you. Find out about them now. This is for your own good. Mail Coupon Today Delays are dangerous. If you have a good invention you should get protection tor it just as soon as possible. Don’t turn this page until: you have clipped and mailed this coupon—you will hear from us by returu mail. REG OFFICE, 30-8 MAIN p. C- 4 z 1 1 TON ew Yor! 115 Mechanical Principles WASHINGT SS. singet Pilg dge CEM o . ther Offices? T Monadment jg, San Fees „g eeevnen and Shown Y: Tau Baneia BE. karent Protection py any f DENT --— "ol your backs game books SU Request the book “Patent Protection” (sent free gend me FREE „> (Nel to inventors). Not only does it tell you what to do for protection, and how to do it—it also shows you 115 different mechanical movements that you may use in developing your own inventions. Inventors tell us they have found these useful. Name cet and Na. su - mM NM REM ZEE NEMO NUM NEM GEM GS REND GENS AED GER AUS GENS UD o nx mm uss HM NEM NEM RED NEAN XN Qus oreste 12 Accept No Substitutes! Always Insist on the Advertised Brondt When Answering Advertisements Please Mention February Modern Mechanix T3

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Constructed from MM plans by Charles Nowak, this “Buddy” sailboat presents a pretty picture as it cruises along. Sail area is 300 square feet and mast stands 26 feet high. A LETTER describing a trim looking boat, con- structed from MM plans, won first prize of $5 this month for Charles Nowak, of Milwaukee, Wis. He writes: Dear Editor: Enclosed is a photo of "Buddy," which I built from plans in your "How To Build 20 Boats" book. There are three "Buddys" here in Milwaukee, but mine is the fastest. (Proved during races.) The boat has proved to be a good rough-weather sailor, taking high seas in a very satisfactory manner. I use 400 pounds of ballast and the total weight of the boat is about 2,900 pounds. Charles Nowak. We compliment Nowak for the craftsmanship evident in "Buddy's" construction. The photo of the craft under full sail undoubtedly will inspire many other MM readers to construct a boat for use this coming summer. 28 An award of $3 was sent to Clyde Kempf, of Canton, Ohio, for his letter in which he says: Dear Editor: Here is a snapshot of my "Runlite" trailer, which 1 built from plans appearing in your book "How To Build Trailers." I use the trailer for fishing and hunt- ing trips and find it very practical. "Runlite" was very easy to build and I have received plenty of compliments on its appearance. Keep run- ning good workshop plans in MM. Clyde Kempf. Judging from the photo, Kempf's trailer is well equipped—a veritable "camp on wheels." ket Readers are urged to accompany their letters to the Workbench with clear photos. Many letters received must be rejected for entry in the monthly contest simply because the photos sent with them are poorly taken, preventing reproduction. *OR An interesting letter received from Mike Liptak, of St. Paul, Minn, was awarded a $3 prize. He says: Dear Editor: Enclosed is a photo of my brother and I holding our five-foot gas model airplane. It represents 100 hours of work. During a contest we filled the model plane's motor with gasoline and it flew out ef sight, but was returned to us the following day. We hope ta see more gas model plans in future issues of MM. Mike Liptak. Mike sent us a clipping describing the flight during which the gas model airplane was lost and Fully equipped with camping paraphernalia, this, home- tyde Kem built “Runltte” trailer enables de and fishing trips in maximum comfort. MI Modern Mechaniz f to make hunting IM plans were used. all we can say is that the model certainly turned out to be a “flying fool,” having made more than 40 good flights since its construction. LE Midget racers still appeal to a majority of MM craftsmen and a letter from William Walker, of Akron, Ohio, describing his home-built racer was awarded a prize of $3. The letter reads: Dear Editor: I am sending you two photos of my midget racer, which I built from plans in your “How To Build It” book. The car does 40 m.p.h. easily and averages about 40 miles per gallon of gasoline. My racer is powered with a single cylinder motor- tyc'e engine and boasts a three-speed transmission as well as internal brakes on the rear wheels. I have driven the racer about 500 miles and didn't encounter the slightest trouble. I am a constant reader of MM and enjoy every issue. Your workshop projects are excellent. William Walker. Midget racer fans, we are certain, will agree that Walker's tiny car is a “winner” as far as appearance is concerned. Congratulations for a job well done, Walker. From far away Australia came a letter written by Donald A. McBean. Awarded a $3 prize, the letter reads: A speed of 40 m.p.h. and mileage of 40 miles on a gallon of gasoline is claim. for his home-built midget racer (top) by William Walker, Lower photo shows front view of car. Dear Editor: You may be interested in the enclosed photo of the good ship "Mayfílower," which was built to MM plans. Your plans and directions certainly are easy to follow. Ship modeling is certainly a test of patience when you have to make every part by hand. Ready-made parts are not obtainable in this country. Donald A. McBean. A beautiful model, McBean. Congratulations! eRe Another letter which wasawarded a $3 prize in this month’s Work- bench contest was received from John S. Phill, of Belfield, N.D., who wrote: Dear Editor: I am enclosing a photo of a built- [Turn to pege 31] Mike Liptak and his brother proudly hold the five-foot “gas”? powered model airplane they constructed. The model fiew out of sight during a contest, but was returned to the boys again, Donald McBean’s model "May. flower,” built to MM plans. February, 1938 29

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OU shoot through a winding tunnel streaked with colored lights, dive under a river, zoom up on the other side, fly past crowded platforms, sway dizzily as you dash around a curve at breakneck speed—it's a crashing, flashing, thrilling scene that thun- ders past as you ride the subway express! Sightseers in New York soon discover the subway to be one of the city's miracles. For five cents they can ride for hours or for days 38 Donald G. Cooley Left——New "York's mayor, Fiorello La Guardia, in the control cab of the train that opened tbe new link of the Independent Subway connecting Queens and downtown Brooklyn. Top-—-A quick.-accelerat- ing, short-stopping train of the Independent Subway pulls into the Hoyt Street station. Subway sta- tions are brightly illuminated and well maintained. on the world's most exciting underground railroad. When the American Legion held its big 1937 convention in New York, hun- dreds of Legionnaires stated that the big thrill of their outing came when they stood in the first car of a speeding subway train and found adventure around every curve. Cave-dweller that he once was, man finds the subway an irresistible lure. There is mystery in every inch of it, the mystery of Modern Mechanix Top——A typical station scene during rush hours. Carrying about 1,000 passengers each, as many as 32 trains enter and leave a station each hour during the rush periods. Right—A subway motor- man at his controls. No current can be applied to the motors until the doors in every car of a train have been safely closed. (I. R. T. photo). Mother Earth who yielded grudgingly to human burrowers. That block which you just flashed past in hurtling seconds—above it rises a $50,000,000 skyscraper. That pres- sure in your ears which warns that you are diving down—over your head flows a mighty river carrying tugs and ocean liners. Actually, New York does not have a sub- way, but subways. There are three systems, the I. R. T. (Interborough Rapid Transit), February, 1938 the B. M. T. (Brooklyn Manhattan), and the Independent, the latter municipally owned. Their routes cover more than 200 miles and on a single day they carry some 4,000,000 passengers. This is equivalent to transport- ing every person in a city larger than Chicago every day. To achieve this major miracle more than 5,000 cars which travel at speeds up to 48 m.p.h. are required. Since Manhattan itself is only 13 miles 39

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^ c V SHING FAS seuga SRMAICA h 2 > EE 205 tST mds SOME. THE BRONX INDEPENDENT CITY OWNED ME di f RAPID TRANSIT RAILROAD | oo - fce i E g Stano ck in Arrian go F r3 i | ó A Nut v CUO aN QUEENS o6 | Fl g oa BROADWAY 3 : Dems Queens pour cyano A nr ie Li L3 i * " 5 m se * i x? HUDSON RAVER MAN HAT TAN PES HUDSON RIVER Oe Ve € [4] Qm f D 4 $ LAE v is Y " E BROOKLYN " Key Stet an suroni ROCKAWAY AV. a ERES a LINES « —_ a RAPID TRANSIT DIVISION CIOXXEXIIIYGTO) ELEVATED LINES saCumNMEEG S SUBWAY LINES am N og ENDING. CaN x ae BATH BEACH S e CULE te, Re SEA 9 cere A T a, Patan” INTERBOROUGH RAPID) SES DISON iver CAPRIS E - FONT ro a, cet an ELEVATED DIVISION | JOINTLY OPERATED ( CoNeY ~ ee cas TRANSIT COMPANY | Shown above is a map of the New York and sub- Owned and operated by the city, the Independent Subway, The majority of the Brooklyn-Manhattan Transit subway routes extend into | ne trus n EE ee LU NER HP IA QU. S mec aa Papeete NM pauore. long, much of the subways’ trackage reaches lyn and Queens, it comes out from first notch. The controller is very much Speed! More speed! Speed with safety! out to suburban regions. The subway runs underground and becomes an elevated. like that used on electric street railways. Speed is the driving genie of the subway under the East River to Brooklyn, under the The place to savor the thrill of a subway The instant the last door closes, the train not alone speed on the straightaway, but Harlem to the Bronx, through the Queens- ride to the utmost is in the very front of the starts to move—a precious split-second has speed on the getaway. Ahead of us, around boro tubes to Queens. In the Bronx, Brook- first car of the train. An open doorway with been gained by that little trick of leaving the [Continued on page 132] guard-chains hung across it is control handle “on.” Two all that stands between you and electric bulbs on the controller " the stretch of gleaming track in front of the motorman light The Subway Comes Up For Air that runs off re eR into up to give him the "all clear" “Time Out" For Periodic Inspections RS IA the dim distance. The motor- signal for starting, but they are : TORUM man's compartment lies behind really unnecessary. While the a steel door which shuts him off car doors are open, no current from the rest of the car. The can pass through the motors; space is just about large enough the very second they close -to accommodate one man, but (unless the controller is "off") since this is a special sightseeing voltage hurtles into action and tour we will edge in with him. almost by the time the last car The train is halted in the sta- has cleared the platform, the tion, the doors are open, and the train is notched up to full control handle is moved to its speed to-maintain schedule. Mee Liao een of © i ü subway car is lifted from its Modezn Mechanix February, 1938 ‘trucks in preparation for thor: ough overhaul. (ER.T. photo).

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. SCIENCE BATTLES Foc MENACE Almost totally obscured by fog, the disabled schooner Uvira is towed into port by the U. S. Coast Guard cutter Pontchartrain. Note the lengthy towline slung between the two vessels. HE maritime nations of the world are spending millions to obtain speed at sea. The Queen Mary. the Normandie, the Rez, and hundreds of lesser liners plow fearlessly through the oceans at express-train speeds, working on schedules almost as iron-clad as those of railroads. Mountainous green seas, breaking in white foam over the bows, might terrify the landsman, but they are of little concern to the mariner, for they menace neither the safety nor the speed of the ship. It is minute droplets of water, so tiny that they hang suspended in air, that endanger life at sea—that cost ship owners millions in wages, fuel and lost revenue. Twenty thou- sand collisions in fog during the past ten years have taken toll of 23,000 lives. Fog is still the big menace to navigation—still remains the challenge to science. A few years ago, while on recruiting duty with the Marines, I tried to get a mother’s consent to the enlistment of her minor son. She wired that she consented, providing that he would not be sent more than ten miles to sea. She did not understand that the high seas are comparatively safe—that it is close to shore, especially at the focal points of traffic, 42 Unaffected by magnetic variations, the gyro compass (above) is used in conjunction with ʻa polarus to obtain accurate visual bearings near shore. Left—The 10,000- ton liner Iroquois with her bow high out of the water after grounding on the Maine coast during a heavy fog in July, 1936. The 112 pas- sengers were safely removed, after which the liner was success- fully refloated. echanical devices — minimize the clammy ~ mists.. death toll. by Bob Gordon In the photo at left, a lighthouse tender crew is shown placing a tank of acetylene gas fuel in a lamp-equipped channel buoy. Above——A victim of fog, the Welboro grounded on the rocks off Fisher’s Island lighthouse in Long Island Sound. near port or in the harbor, that the real danger lurks. The most vital concern of a navigator is to determine his position when approaching the coast—to keep his ship in deep water and out of the path of other ves- sels navigating in darkness or fog. For this last ticklish stage of an ocean journey, the U. S. Lighthouse Service main- tains 25,000 aids to navigation along our coasts and inland waterways. There are 2,000 such aids in the vicinity of New York alone, 600 of which are within the harbor. These aids consists of lighthouses, lightships, buoys and radiobeacons. The U. S. Navy also maintains several radio stations at strategic points along the coast. Upon request these stations will take radio compass bearings and transmit them to the ship. With bearings from two or more such stations plotted on the chart, the ship’s posi- tion is readily determined. The ship requires no equipment other than its regular radio to receive such bearings. The radio, however, is not absolute. With only two bearings the lines will meet at a single point. A third bearing will seldom 43

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MAN MAKES HIS OWN IHE diversified chemical manufacturing industry of America is finding a way make this country free from dependence on foreign sources for an increasing number of vital raw materials. Only a few years ago, America depended on the nitrate beds of Chile for fertilizers and raw materials for industry. Today, it makes its own ni- trates from the air. . Camphor was from time immemorial a natural monopoly of the Far East. Today, : 2 America makes its own synthetic camphor tay eee incl QE for medicine and the needs of industry. A its physical structure is the same even though its - A : Mr chemical: composition is different. Photo shows one . large and increasing number of medicinal of numerous steps required: in processing neoprene. and other compounds, formerly imported, are now being produced here. And now rubber may be added to this list of essential raw materials. Rubber is a vital element in our life. It is used not only for tires but for thousands of other products that are essential to our industrial civilization. More than ninety- nine per cent of the world’s rubber is grown in the tropics. Many attempts have been made to grow substitutes for rubber in the United States, but none has ever succeeded. Millions of American dollars, British pounds, and German marks have been ex- pended during the past fifty years in an attempt to produce a synthetic rubber; t is, a product identical with natural rubber made by chemical means, preferably from raw materials. that are freely available in these industrial countries. All of these efforts to produce a true synthetic rubber have met with failure. Germany, during the World War, did produce a synthetic uu E I Nu product that was used as a substitute for qe mp e pea rubber, but it was a very poor imitation ipee for chem pue esee of the natural product and consequently its production was dropped as soon as the war ended in 1918. Night view of the E. I. du Pont de Nemours & Company plant at Deep- 50. water, N. J. which can D produce one million pounds of neoprene yearly.

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National Miltary Park. Center——-Making a model Indian village far use in an historical exhibit. SS Lowere-Pulling the mold from a clay relief map. Top phoeto-—RHelief map of Vicksburg {Miss.) by Walter E. Burton CHE man in the lookout station leans for- -L ward tensely. His eyes ache as he gazes through his binoculars. Yes, there is a wisp of smoke all right; and it seems to be grow- ing in size. Looks like the fire might be near North Fork. The lookout leaps across the floor to a re- lief map hanging on the wall. With his pencil he traces a route the nearest fire-fighting crew can take to reach North Fork. Two or three times he has to back up and detour around small, but deep, canyons or small streams whose sides are steep, and which might delay the crew too long. It is but a matter of seconds until he has worked out the shortest and easiest route; and not many more seconds until the men from the nearest Station are preparing to depart. In a few hours, thanks to quick work of the forest fire fighters, thousands of dollars worth of timber, scores of wild animals and perhaps even a number of human lives have been saved from the Fire Demon. But the story might have been different, if that relief Not child's play, but a map had not been at hand for pointing out the quickest route to the fire. Behind that map is a story of Uncle Sam as an up-to-date builder of models and man- hood. For the map in question is one of the products of government model laboratories operated by Civilian Conservation Corps boys as part of the Emergency Conservation Work program. There are two such laboratories in the country. One of them is at Fort Hunt, A sculptor (top) checks a clay model to be used in making a diorama. The hunter (above) was modeled for use in a miniature group depicting commercial Buffalo hunting during pioneer days. A CCC worker (left) com- pletes the running gear of a. wagon to be used in a model display. Considerable re- search is undertaken to as- sure authenticity of details in fully completed models. Virginia, not far from George Washington’s historic home at Mount Vernon. The other is at Berkeley, California. These laboratories carry out projects of model building and relief map making sanctioned by a committee. The models serve a variety of useful pur- poses. Perhaps the superintendent of a na- tional park will want a relief map of the park to exhibit to visitors to acquaint them with the topography of the region, or a diorama valuable service is this branch of government activity.

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Completed, the inlaid stool makes a useful living room decoration. OR your next lathe project, why not make this lovely inlay foot stool? .It has an unusual design and the striking contrast between the white pine and figured gum top makes fit addition to any room. The first step calls for placing the stock, for the top, on the lathe face plate and turning it down to size. The small, center screw type was used throughout this job. Next, the recess in the top side for the white pine disc is cut out, care being taken to have the cut square. The piece is then removed and a block of white pine l-inch thick cut down to make a tight for the hole. The cross design is laid out on the pine and this jig sawed out with a slight taper—the bottom being very slightly smaller than the top opening. This taper insures a tight glue joint for the inserts when they are tapped home. Proceed by putting the block for the top back on the face plate, wiping glue inside the recess and around the rim of the pine block, then tap home with a block of wood under the hammer. Before doing this a pattern is taken of the insert size. Four pieces are sawed to shape, slightly oversize. These are fitted one at a time, their 72 STEPS IN MAKING an Inlaid Footstool by Dale R. Van Horn size reduced by holding them lightly against the sanding dise. Glue holds them firmly in place. All four inserts, however, should be fitted and a trial assembly made first to insure a good fit. While the inlay design shown is simple and of plain lines, any suita- ble figure can be used, such as the outline of a scottie, swan or some other appropriate design. Scribe a circle to designate the posi- tions of the top leg dowels on the under side, divide into 6 spaces and, with a cloth pro- tecting the top, bore the dowel holes 34-inch Left— Tap white pine inlay disc in place with a block of wood and a hammer. The glue should be pre- viously applied to the disc so as to. hold it in securely. Below — Fit each piece, inserted in the cross, in the white pine disc in- dividually. After a good fit has been obtained, apply glue to the edges and hammer them down into position. Jig-saw the white pine disc to a slight taper so the figured gum inserts can be tapped down to provide a tight fit. ae \ Z 6 HOLES y NE SPACED L EVENLY 6 = 1 "i X 2i'nao. E ‘ot 29 i deep. Put the piece back in the lathe and finish uec 1 with a good coat of clear lacquer. Later rub it s lightly with No. 000 steel wool and finally wax. The base is a simple turning. To get away from such a large piece setting flat on the floor and perhaps teetering a little if the floor is not true, a depression is turned 44-inch deep in the bottom side of the base. Most of the remaining wide, shallow rim is then sanded away to leave 4 or 6 feet as indicated. These will not be conspicuous, nor need they be included if not desired. They will be desirable, however, under most conditions. [Continued on page 120] Apply glue 7 to each dowel before fitting the top and bottom to the legs. Glue is also applied to inside of holes. WHITE PINE FIGURED GUM DISC I" DEEP INLAY PIECES p, E M C un : 2" STOCK "SECTION THRU BASE SHOWING SANDED FEET o2! / 3 -——— 62 | TURN 14" DEEP. Left — At this stage the top is ready for polishing. The deco- rative inlay around the edge of the top is a narrow pine strip glued into a "V" groove made with a shaped file tang. Fin- ish the top by apply- ing a coat of clear lacquer. When dry, rub with No. 000 steel wool and last polish with wax. 2" STOCK FIGURED GUM. ~ z E f LEGS 7/8" ; SQUARE — CORNERS. ROUNDED SLIGHTLY SANDED Gs S COMPONENT PARTS

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This home-made glass blowpipe de- livers a hot flame. Inner tube is for air, outside tube for gas. "Gathering" glass is an impor- HE reason that amateur glass blowing is such an in- teresting hobby is that the work acts as a stimulant to your tant operation. Notice the small glass tubes and corks used for holding larger tube in the flame. Left-—Glass blowing with a professional type, nine jet gas-air burner. creative ability. With very simple and inexpensive tools, in a corner of a room or in the attic or basement, you can quickly learn to make dozens of useful and ornamental pieces such as vases, small glasses of different shapes, beverage sippers and other articles of that nature. With further practice and experience you will not find it difficult to make the tiny animal, bird and flower novelties or “what- nots,” which are so popular in the home, and know that the design is original and that a similar article cannot be purchased in the stores. ý i If you are an amateur chemist, a knowledge of glass blowing will enable you to repair broken retorts and other apparatus, in Modern Mechanix The attractive bud vase at extreme left was made by blowing a series of bulbs and pushing them flat. The bird nov- elty was shaped from a solid glass rod. by Kenneth Murray Close-up photo at right shows forma- addition to making test tubes and other small equipment. Or do you prefer to dabble with electricity? Then try blowing glass bulbs for homemade experimental electric lamps, along the line of the mercury-are type of light, which is similar to the well-known "neon" tubes. Amateur model makers frequently have use for miniature glass parts, and in fáct there are very few crafts or hobbies where a knowl- edge of glass blowing would, not be useful. Locate the glass-blowing laboratory in a convenient corner free of drafts and with poor illumination, so that it will be easier to judge the condition of the heated glass. An ordi- nary workbench, about 3 feet high, is satis- factory, or use a kitchen table. Cover the top with sheet asbestos, or preferably asbestos board, and at the back provide a rack for holding your stock of glass tubing in various sizes. .February, 1938 tion of a beverage sipper from tubing. All amateur glass blewing, and a con- siderable amount of professional work,. is done with glass tubing instead of using molten glass in a heated retort. You will find that soft sodium glass is most satisfactory; it should have walls at least 1 mm thick, and a bore of from 5 to 10 mm for general work. Quite often you can purchase this at a local drug store or high school laboratory, other- wise you can order it of a scientific supply house. Ordinarily the tubing is offered in 5 or 6-foot lengths and costs as little as 25c a pound, according to the amount purchased. Professional and advanced work is done with two or more special blowpipes which oppose each other and are fed with both gas and air under pressure. A professional outfit of this kind is shown in one of the illustra- tions. However, the beginner can handle small work with the aid of a bunsen burner 77

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PACKER BEARING (SHIM UP TO REQ'D. HEIGHT) I" DIAM] SHAFT yo BAR IRON UPPER GUIDE MAIN BEARINGS FROM DLD CAR SET AS SHOWN TI ON TRANSVERSE | CONNECTING HARDWOOD BLOCKS | ROD POST 1g" GUARD SUPPORT LENGTH OF OLD REAR AXLE [-1/4" DIAM. UB. E 1 END UTILIZED 26" — DRIVE PULLEYS TOSUIT ANGLE IRON BASE-SEF FIG.3 BELOW MOTOR BEARER 3 RE SEE DETAIL OF Y MOTOR MOUNT Fic. 2. REAR ELEVATION OF SAW SHOWING ALTERNATIVE BASE FRAMING If this base is anchored solidly to the floor the legs may be given considerably less spread, making it still easier to build. The frame is either bolted or welded to- gether. Note that the top rails are mitered at the ends. The saw frame on the origi- nal was taken from an old gang plow. However, it is simply formed from ordinary 34 by 2-inch bar iron to the dimensions given in Fig. 5. When obtaining the bar iron enough should be purchased to cover the other frame com- ponents as shown in Fig. 5. Slots are cut in the saw frame to permit ad- justments of table column and guide arm units, also, although not shown, for the upper shaft anchorage. Exactly 634 inches from the U end of the saw frame, are drilled and tapped for the %-inch and %g-inch bolts 82 BAR IRON T BEARER(2 &£Q'D.) 3 [X : li s GE ucc FLOOR LEVEL Varz ar u FIG.3 BASE DETAIL w^ which hold the tension adjustment pipe in place. The 5g-inch tap occurs at the top of the frame as shown. The exact purpose of this pipe and the manner of fitting it will be explained later. In the meantime, tap as mentioned and the frame is ready to set up on the base. The frame and a 9-inch length of 94 by 2-inch bar iron rest parallel, directly on the base as indicated. Across them are placed two timbers which carry the main drive bear- ings. As the exact size of these timbers de- pends upon the style of bearing obtained, the dimension will have to be fitted to the job. It must result in the 19-inch dimension given between centers of the band wheels and, as the bearing blocks referred to are bolted clear through the bar iron members into the top rails of the base, it will be necessary to de- cide upon the main shaft bearings before bolting the saw frame down. A length of old rear axle sawed off, re- taining the hub end, makes a good main drive shaft. Two main bearings from an old car FIG. 4 MOTOR MOUNT DETAIL - |4 ANGLE IRON 3" CHANNEL IRON The plan drawing at upper left shows the basic dimensions. The 19-inch dimension be- tween shaft centers is important and must be provided for. Lower de- tail shows motor mount and angle iron base. \ 5/16" STOVE BOLTS(ORYOINTS. MAY BE WELDED) SS As engine will serve for the bearings of this shaft. (Ford T bearings were used on the saw depicted here.) The bearings are bolted, as shown, to the hardwood timbers or bearing blocks; the exact width and height of these blocks depends, as already stated, Modern Mechanix upon the type of bearing used. The band wheels are 12-inch brake drums complete with hubs, in this instance from an old Elgin car. They are faced with rubber taken from an old, large inner tube (see Fig. 8) and mounted with the flange side facing the frame. The lower drum is fitted directly to the axle shaft that forms the main drive shaft of the saw. This presents no difficulties at all, but the mounting of the upper drum is slightly more complicated. The upper wheel is supported by a 1-inch shaft which is threaded on one end. The shaft passes through the ball bearing (which in this wheel is re- tained) and is clamped to the inner race by means of a nut and washer on either side, the’ DRILL AND TAP Ec 2d FOR 5/8" DIA, a P 5/8" BOLT TURN DOWN FOR 1/2" DIA. SHOULDER V2" PIPE d TENSION ADJUST- MENT c ‘va"Bout\]) [| 23" BOLT THRU HARDWOOD BLOCKS TO TOP OF BASE FRAME 3/4" BAR IRON Fic.5 DETAIL OF SAW FRAME ball bearing being held in place by the outer hub. Tbe drum now revolves freely on the shaft, which in turn is anchored to the frame either in the [Continued on page 124] February, 1938 ADJUSTMT. SLOT FOR TABLE COLUMN N m SLOTS 7 TANN m = The simplicity of the id Beppe ie band red E is verified by these pictures show- EM Fic.6 ing both front and side views. BAR IRON UPPER GUIDE ASSEMBLY SUPE ROD | ceyenr ro ORUM d STRIP OF || j | 5 HEAVY INNER Z ADJUSTMENT SCREW GUIDE ROD $7 SLEEVE ( E ET a FLANGE VN BRAKE DRUM WITH HUB Fic.8 DETAIL OF BAND WHEELS A RIVET 2 BRAKE BANDS TOGETHER Pd TWIN STEEL EISTON ROLLERS PIN. 2" WIDE WASHER ADJUSTMENT SCREW zc " f WING tá B Ave [4 STRAP IRON C STEEL PIN RIVET OR BOLT ^ LOWER GUIDE N ROLLER FiG.9 DETAIL OF GUARD SUPPORT PIS TON PIN & GUARD JOINTS Frame dimensions and miscellaneous details of the band saw fittings are shown in this group of details. The manner in which the lower guide roller and piston pín projects from the saw pivot is shown in Fig. 7 insert. 83

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by Prot. Victor Lewitus Make a strong soap solution by mixing shaving soap and water. After taking a puff on a cigarette, blow the smoke through a bubble pipe to make a soap bubble. The inside of the bubble then will contain the white smoke, and when it breaks, it does so with a puff, furnishing a very striking experiment. A clay or corncob pipe will be more suitable than the briar variety, inasmuch as the soap mixture probably will make the pipe unsuited for further smoking. FIGHTING FIRE WITH SOAP BAKING 7 CIDER VINEGAR Into a glass of water place two tea- spoonsful of. bicarbonate of soda (baking soda). After it has dis- solved, add one or two teaspoonsful of soap chips, which should be dis- solved before proceeding with the experiment, Finally add some ordi- nary vinegar and notice the thick, voluminous foam that forms. This type of mixture may be used to ex- tinguish ‘a fire, and is very successful because of its tenacious character. If a sufficient quantity is avail- able it will act as a blanket covering the burning area. 86 Into a narrow bottle place a few crystals of copper sulphate or “bluestone.” Cover these with a few inches of water. Then add several pinches of soap chips and shake the mixture for an instant. It wili be found that a beautiful emerald-green solidified mass develops. This is caused by the soap solution reacting with the copper sulphate, which has an acid reaction. SHADES OF IRELAND LIDIFIED o EEN MASS — V]: Below—Fill three drinking glasses of the same size half full of water. Use ordinary tap water in the first; the same water for the second into which has been placed some salt; and distilled. or rain water for the third. Place small equal quantities of soap into each glass of water and shake each for the same length of time. Notice that a thick lather will form quickly in the dis- tilled or rain water while practically no suds will appear in the salt water. The tap water probably will have suds but not as many as in the rain water. This experiment will show the softness of tap water as compared to the other extremes. HOW HARD IS YOUR WATER 7? 302. LIME WATER Below—Into a small glass receptacle place two ounces of water. Then pour into the water a half an ounce of mineral oil. Shake the combi- nation and note that within a short time after the shaking, the oil and water will separate. Add one ounce of soap chips to this solution, and this time after shaking, the oil and water will not separate. This shows that oil and water will mix under the proper conditions. MINERAL OIL OIL & WATER MIXED SOAP CHIPS. Place two quarts of water in each of two pans and add some salt to one of them. Ask someone to wash his hands in the water to which salt has been added. He will find that try as hef- will, no lather will form, while if yoi wash in the plaig water, an abu dance of lath will be obtaigf NO LATHER MERGUROCHROME 3 DRO LINSEED OIL This burn-aid soap will be found to be a very useful preparation to have on hand in the home at all times. Children particularly are subject to many minor burns, and because of the pink color of the material, they probably will have no objections to having it applied when necessary. Into a glass vessel pour three ounces of lime water (obtainable at the drug store). Add to this, with constant stir- ring, linseed oil until you have incorporated three ounces. Mix thoroughly by shaking, in a six- or eight-ounce bottle. During the shaking, the material will turn to a milky-appearing substance. To this add about ten drops of mercurochrome solution (obtainable at the drug store). This last addition will turn the solution a pink color. These simple experiments will be found interesting and simple for the amateur chemist, and give to the experi- menter a broader knowledge of soap—one of the most common and useful things in life. While in continual use by every person, few understand its workings other than for washing purposes. 87

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1 ROD FLATTENED d MINNOW, PAIL The ice fisherman’s gear need not be elaborate. All essentials are shown above. Fishing can be done, mechanically, with “tip-ups,” or Rand jig- ging, as pictured at right, may be employed. READY-MADE IBIpSUBS Landing Your Fish (ROM our northern snow-belt states, up through Canada and even Alaska, ice- locked rivers, ponds and lakes are dotted in winters with men and fishing outfits. Even snow and bitter winds driving over their frozen surfaces fail to chill the enthusiasm of inveterate fishermen. Despite conservation legislation limiting catches and shortening fishing seasons, in- terest in the sport is definitely on the increase. Many mere onlookers of a Sunday afternoon return the following week-end with the sketchy outfit required to try their skill at ice fishing. Good luck or bad, they usually succumb to the multiple lures of keen frosty air, the contrasting beauty of black evergreens against snow-blanketed hills and the exhilarating feel of lively perch, pike and pickerel tugging against a taut line. Some of the charm of ice fishing lies in its uncertainty. One day you may pull a good string from a single hole, but catch nothing when you hurry back to it the next morning. Fishermen on one side of a pond may be seen frantically pulling in perch, hand over hand, while less fortunates on the other side flail 88 idle hands and stamp cold feet in an effort to keep warm. Familiarize yourself with the laws of your particular state as regards ice fishing before gathering your gear together. Yellow perch, pike, pickerel, whitefish, grayling, bullheads, lake herring and trout, and others, may be taken through the ice—if your particular state permits. Even the methods used—the jigging spoon, tip-ups, “plunking” for ciscos and spreader fishing for smelts—the subject to our everchanging legislation. Ice fishing tackle is characterized by its simplicity. The majority pin their faith to “tip-ups,” either buying excellent ready- made affairs at reasonable prices or pattern- ing their own after one or another of the many amateur designs. The ribs from an old umbrella may be used to help make the half-dozen “tip-ups” re- quired, A lath, not quite as long as the rib, is used as a wood support, notched at one end and the rib hung in the groove there by driving a rivet through the side of the notch and on through the hole in the center of the rib to form a T-like affair. The line is tied — to one end of the rib and over the other is . not be fancy, One slipped an adjustable weight such as a lead bullet slug, the rib tip being bent to prevent it from slipping off. The weight should be just sufficient to balance the pull of the set line. A “tell-tale” flag of cloth is tied (preferably to the weighted end) to signal the fisherman of a bite. The support is shaped from a thin 3-inch board, 20 inches long. This is whittled roughly into a wedge-shape and a 1-inch hole bored three-quarters of the distance from the larger end. A 14-inch peg, driven to a tight fit through a hole in the smaller end, permits winding the line for adjusting to the depth of the water being fished, while the “tell- tale" threads through a hole in the other. Use 2-foot broomstick-like poles, with a loose fit through the center hole, for cross arms, so as to lighten the weight of gear to be carried. A tip-up can be made at the pond by lash- ing two lengths of sapling together in the form of a cross. Tie the line to one end and fasten a handkerchief to the longer length. The disadvantage is that the cross arm may Through Ice by Dad Williams “Tip-ups’’ need made from a length of sapling will serve admirably. A jigging rod can be whittled to shape from a stick 18 inches long. Attach a cleat to one end for securing the line. If desired, a leg from an old chair may be used as a jigging rod. Purchase the spoon ready- made; or cast it from block tin. “LEAD WEIGHT This efficient mechanical ice fishing device is easy to make, It is merely an umbrella tib supported in a notched board driven in ice. A bullet siug, drilled through center, serves sasha counter: balance. Below— RED -up^ made from saplings.

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The candlestick uprights are formed from two strips of copper, twisted into a spiral column. Template and cross-sec- tion of candle cup is shown. in plan at left. (IB GA. COPPER} E 25 SAUCER BLANK DETAIL OF 3" COLUMN 32x F ROLL AROUND 3/4" DIAM BAR. FLATTEN e FIG 3f DETAIL OF CANDELABRA DA 1 N AERE “ROLL AROUND 7 iz 7/8" DIAM. BAR. | 5 3 — T j j j BASE BLANK 3 16 GA.COPPER a ifa e 21— 1 eme an EXE The candle cup is hammered to shape over the tip of the anvil, as illustrated in this scene. RODUCING metal articles in the home workshop does not involve the use of expensive bending ma- chines or other costly equipment. The candlesticks, ash tray and picture frame described here are not only easy to make but provide the craftsman with something that he can show his friends with a feeling of satis- faction. Tin snips, ball pein and planishing hammers and an anvil are all you will need in the way of tools. In making metal candlesticks the crafts- man is usually at a loss as to how to form the cups. Also, it is almost impossible to produce an attractive column for a tall candle holder. In the production of the pair of 92 HAMMERED COPPER WARE FOR HOME by Dick px neon Place the upright strips in the vise and twist them to shape by grasping them in the jaws of a wrench. Left— Hammer the sauc- ers to shape with a ball pein hammer. candelabra illustrated here both of these obstacles have been ovefcome very beauti- fully. The column for each piece is of j;-inch Sheet copper, 34-inch wide by 1042 inches long. The edges are filed smooth and the pieces hammered. Place two pieces together with the ends even, and set down in the vise 2 inches and clamp. Then, grasp them with a small monkey wrench and twist into a spiral as is illustrated, making it about 3 inches long. The spiral, when twisted tight, Modern Mechanix CRAFTSMEN Ash trays like this one are easy to make. spring clip holds them securely to the edge of table. The clip may be — ' twisted to form a handle — ,/ when using the trays in the conventional manner. / Modern in style is this hammered copper picture frame. Pattern and per- spective are shown below. BLANK FOR UPRIGHT ise BEND ON DOTTED LINES, - Yh EA $ Right — Shap- ing bowl on anvil with ball pein hammer. 13/16” ra 5 s li AN $ T AFTER BENDING |, BEFORE BENDING The metal frame is bent in the vise between hardwood blocks, as illus- trated in the photographs below. 3 TRAY BLANK (t6 GA COPPER) will hold together evenly, making a very attractive column. Bend the two lower ezds to shape, and spread out flat with the planishing hammer, drill holes for rivet- ing to base, then bend the other ends out and shape ` as shown. Drill two holes in each for riveting to candle saucers. . Viet me . The base is of 16-gauge sheet copper, 2% inches River e combination clip and ipee holder wide by 8 inches long, hammered and the ends are rolled under. This is done by rolling them around [Continued on page 130] February, 1938 93

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NCREDIBLE, but indeed true, the hair of no two of all the thousands of different species of mammals is exactly alike. Amazing, too, that the microscope is an important tool in this great industry as it is in so many others; the limitless powers of this unique instrument seem capable of invading every field. A journey via your microscope into the mysterious domain of fur is certain to prove fascinating. Examination of hairs under a microscope is a meticu- lous business, and yet the technique is very simple. Hairs as obtained from the body or from pelts are dirty and greasy and must be thoroughly cleaned in order to reveal their minute structure which, like the fingerprints of the human hand, affords a positive means of identification. The solution for cleansing is a mixture of equal parts of 95 per cent aleohol and ether. As ether is explosive, keep it away from all flames! Hold one or a few hairs with a pair of fine forceps and wash them back and forth slowly in the fluid for a few minutes. The hairs are next dried over an electric bulb, and are then placed on a scrupulously cleaned slide and capped with a cover glass for tem- porary inspection under the mieroscope, without any mounting medium. Any dust or dirt interferes seri- ously with determination of the exceedingly fine scales which clothe the exterior of the shaft. If any dust or grease remains on the hair, repeat the cleaning, drying and This photomicrograph of a beaver fur hair illustrates a simple medulla of the discon- tinuous ovate type. Cuticular scales may be seen at the edges. by Julian D. Corrington, Ph. D. 96 inspection, mounting perfect specimens in balsam. Staining helps bring out the cuticular scales, the best reagent being a saturated solution of safranin in 95 per cent alcohol. This means the maximum quantity of the dry powder that can be dissolved by a given amount of the alcohol. Immerse a hair in this stain for two minutes, then dry as before and mount in thick balsam. Don’t use thin balsam as the stain will ruh and spread. Hairs are commonly mounted unstained, however, so this procedure may be omitted if desired. Specimens are not at all difficult to collect. Provide yourself with a number of gelatin capsules, preferably the kind that veteri- narians use in putting up horse medicines, and ransack first the various fur pieces be- longing to feminine members of the house- hold such as coats, neck- k pieces, trimmings and gloves. It will do these garments no harm at all to remove the three or fourhairsthatere needed. In pelts like mink and fox, collect both the over and under fur hairs, which can be mounted together under The protective hair from a mink pelt is shown in the photomicrograph below. It illustrates a simple medulla of the continuous nodose variety as it appears when viewed through microscope. Right-——Before mounting on slides, hairs are cleaned in alcohol and ether bath. LTA An VLA ASA TAK 3 $ ; = j S No ddt dT $ kr ? dd us o vM UD VUL The fur of the beaver is only one of the many types that is well adapted for examination and study under microscope. the same cover glass. The typical structure in each case is to be found about one-third of the distance outward from base to tip of the entire hair, and this is the portion to put in your capsules for mount- ing. Of course the outer two-thirds or more in many garment furs will already have been removed by clipping, as in Hudson seal, which is trimmed and dyed muskrat, while some hairs even when complete are so short that their en- tire length will go under a cover glass, so these factors have to be taken into account in collecting material. Then come the domestic pets, as cat, rabbit and dog; the farm animals and occasional opportunities offered by unusual captures or pets, and perhaps some friend connected with a zoo or museum can be en- listed in this enterprise. Finally there is the fur store and commercial supply house as sources for the larger slide collections. Pay particular attention to keep hairs from different sources in separate capsules so [Continued on page 122] 97

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An old tube base is used to connect power leads to the r.f. chassis. Two are used, one for oscillator power supply and one for amplifier supply. DUMMY ANTENNA FOR TESTING The amplifier power supply. T1, the plate transformer, is at the right. T2 furnishes power for the 866 filaments. The filament transformer for the T55 is not shown, as it is mounted near the rear of the r.f. chassis. The swinging choke is behind the 866's. The bleeder, R5, is shown at the rear. voltage greatly shorten tube life. Saturated chokes have no filtering value, and they, therefore, might just as well not be in the circuit. The point to be remembered is: Use a power supply capable of delivering its rated output. While emphasis is placed on the selection of power supply equipment because this part of the transmitter many times is overlooked, r.f. section components should be selected just as carefully. Nothing is more disturbing than having individual’ parts break down during use. The experienced amateur knows, but the Parts Required 100,000 ohms 1-watt (IRC BT-1) 35,000 ohms 2-watt (IRC BT-2) 10,000 ohms 10-watt (IRC DG) 5,000 ohms 10-watt (IRC DG) 60,000 ohms 200-watt (IRC HOA) 400 ohms 10-watt (IRC DG) .00015 mf. (Cornell Dubilier 4-6T15) .01 mf. (Cornell Dubilier DT-10S1) .01 mf. (Cornell Dubilier DT-10S1) .00014 mf. Hammarlund MC-140-M) .00025 mf. (Cornell Dubilier 4-25T25) .000020 mf. (Hammarlund MC-20-MX) .006 mf. (Cornell Dubilier 4-12D6) .006 mf. (Cornell Dubilier 4-12D6) .00015 mf. (Hammarlund MTC-150-B) .002 mf. (Cornell Dubilier 4-22020) 2 mf. 2000-volt 2 mf. 2000-volt .00035 mf. (Hammarlund TC-350-C) 0-100 milliampere meter 0-50 milliampere meter 0-200 milliampere meter 2.5 mh. choke (Hammarlund CH-X) 2.5 mh. choke (Hammarlund CH-X) 500 milliampere choke (Hammarlund CH-500) 1460-0-1460 (Kenyon T-666) i 2.5 volt 10-ampere (Kenyon T-360) 6.3 volt 3-ampere center tap (Kenyon T-351) 100 T4 7.5 volt 4-ampere center tap (Kenyon T-353) Chl 5-18 Henry swinging choke (Kenyon T-513 Ch2 10 Henry filter choke (Kenyon T-176) 1 Taylor T55 tube 2 Taylor 866 tubes 1 Ratheon 83 tube 1 Ratheon 6L6 tube Xi holder (ICA No. 414) 3 grid caps (ICA No. 870) Insulating rods (ICA No. 2175) Fuse mounts (2) (ICA No. 2342) Terminal strip (ICA No. 2413, No. 2420) 3 dials (ICA No. 2169) Standoff insulators (ICA No. 2300) Insulex standoff insulators (ICA No. 2338) 8 four-prong sockets (Hammarlund S-4) 1 five-prong socket (Hammarlund S-5) 1 eight-prong socket (Hammarlund S-8) four-prong coil forms (Hammarlund SWF-4) 5 flexible couplings (Hammarlund S1, S2 (ICA No. 1230) E 1 metal chassis 10x12x3 (ICA No. 1515)' 2 standoff insulators with jacks (ICA No. 2304) 2 transmitting plugs (ICA No. 403) Bakelite tubing 6"x215" (ICA) Miscellaneous wire, bolts, nuts, washers, screws, etc. 2 four-prong tube bases 1 or more crystals Modern Mechanix OLD TUBE BASE N. S FILAMENT A dummy antenna always should be used when testing the transmitter. L7 should be a coil of approximately six to eight turns and mounted so that coupling with L5 may be varied. C13 should have a capacitance, February, 1938 L5 and L6 are coupled by one or two turns of wire around each coil as indicated. | Antenna then is clipped on L6. Correct position for clip is deter- mined by experiment. ANTENNA COUPLING UNIT ANTENNA 101

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Constracted of sitnple and easily secured parts, the photo spotlight mem. at top wil sire LUE to to obtain striking eft through use o Phadimr and light contrast. Steps in making spotlight ate (1) cutting lens bole in auto fob cap with zaol saw; (2) bend- mg kurhoMing d brackets which g steel: um Reaching jn Dr ry to tim o! Qs with bolts; (4) bolting the mounting swivel in place on sec- den Su of al Stovepipe, 12 inches long, which serves as wall of spotlight; H4 F YOU want to achieve the latest and most modern effects with your indoor photography this winter, you will find a - good spotlight almost a necessity. This one is entirely up-to-date both as regards performance and appearance. With it you can make sparkling photographs with bril- liant highlights and rich, black shadows that stand out amazingly from the usual run of medium-tone, gray pictures. Interesting, too, is the appearance of the finished lamp; you will agree that in de- sign and finish it has all that could be asked for in a factory-made article, yet all of the parts are common and inexpen- sive. Exclusive of the lens, you can build this spotlight for less than a dollar, using new parts. The lens will probably cost several dollars more. The first stop will be at the hardware store, for a 12-inch length of 6-inch stove- pipe. This. should be cut from the un- - erimped end. You will also need an 8- ' inch piece of !s-inch brass pipe, threaded at both ends to take a keyless socket and ornamentel brass loop which you can get at an electrical supply store. In addition to a friction swivel and various small parts, most of which you can retrieve from ihe junk box, you will need two automobile hub caps of about a 6-inch diameter. The kind shown in the illustrations are for a popular make of automobile; they fit snugly into the ends of the stove pipe, and being heavy and chromium plated, they make a fine appearance as part of the com- pletely finished spotlight. Most of the constructional and assembly a hole in one hub cap for the plano-convex „ever. Condenser lenses are no longer used 'on modern high-intensity projectors and can MODERN details are explained by the photographs. Cut condenser lens, which you can get at a camera supply house. It is a good plan to first consult a local theatre manager, how- usually be picked up for a small sum. The method of attaching the lens inside the hub - cap, as shown in the accompanying photos, will hold it very securely and yet allow for expansion due to heat from the photoflood lamp that is used in the finished spotlight. The piece of brass pipe serves as a control rod for focusing the lamp and also as a con- duit for the rubber-covered lamp cord. It passes through a brass bushing which is bolted over a hole in the center of the other

The focusing rod bushing is bolted on the inside of the hub eap (5) and provided with . a simple screw clamp outside (6) to permit easy control.

PHOTO .- < Economical and easy to build, thisspotlight gives excellent performance. y Kenneth Murray As an example of what the home- built spotlight can do to provide light and shadow contrast, . study the photo reproduced in circle. 105

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Above: "How's the air up there, big boy?" asks this tiny man of his larger self. Both figures were po: by the same model. Right: "Need for Potato Control!" One tuber like this is a crop all by itself. 108 Measuring the image on the ground glass before photographing to make sure the object will be the right size to correspond with the other print. by Paul Hadley HE making of composite, or combination photos, is one of the simplest branches of trick photography, yet is one which the amateur photographer seldom attempts. Easier by far than the double exposure or distorted perspec- tive pictures, the results are more unusual and bizarre, in that parts of any two or more photos ` : ment is necessary in making these may be combined to make a freakish result. Professionals often resort to this method in making "photomontages, which are often seen in publications. Probably most of you have seen the novelty photo cards in which, for instance, a wagon is seen creaking under the weight of two giant apples which it is carrying to market, or perhaps an ear of corn being loaded on a flat car with a derrick. Many other variations of this type of picture are to be found, all of which were made by the simple method of combin- ing parts of several prints to make a whole. No expensive photographic equip- pictures. One should, of course, use a camera on which the image can be seen full size on the ground glass before making the exposure, and which has sufficient extension of bel- lows to allow copies to be made of the combined prints. The larger size plate of film accommodated by the camera, the better, for this gives The potato was photographed close up, the print cut out, and then pasted on the photo of the man and the wheelbarrow. Scraping the edge of the potato print with a knife or sandpaper to make it thin allows it to be pasted down without a tell-tale line showing. This “prehistoric monster” is simply an enlarged photo of a rhinoceros, on which a smaller photo of the hunter was pasted; the combination was then copied through the camera. _ you a better chance to study the composition of the picture before making it. A copy lens, which can be purchased from any supply house, will enable you to make closeup photos or copies on cameras which do not have the double extension bellows. The possibilities of composite photos are infinite, and the results you will obtain are limited only by your imagination. The ac- companying illustrations show examples. of a few of the effects. One shows a modern huntsman armed with a repeating rifle about [Continued on page 126] 109

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Pictures of unusual effect can be made by photographing buildings illuminated with floodlights. This picture of the Nebraska Capitol building shows the striking effect of greater height and contrast which would not be evident if photo were made in daylight. The scene was snapped on a cloudy night on super-pan with camera at f. 4.5 with an exposure of 30 sec. Commercial ortho film with 3-minute exposure is also effective for taking outdoor night photos. Owners of vertical enlargers often find it difficult to provide their projection prints with neat borders. Simple frames formed from 1 by 14-inch lattice strips and painted dull black on the inside offer the solution. Placed over the printing paper, they not only serve as masks, but hold the paper flat on'the easel of the enlarger. A simple tester for testing flash guns is shown at left. It is merely a 3-volt flashlight bulb inserted in a male attachment plug and wired to prongs. Plug is then inserted in female plug and screwed into flash gun. crinkled foil attached to a wire frame. Its use will provide better contrast on still subjects taken ihdoors with a time exposure. Center illustration shows a handy reflector made from Use it to reflect light on dark areas. Right—To move a camera without disturbing the tripod a simple tripod truck formed from light stock can be easily built. Ball-bearing furniture casters permit it to be moved without difficulty. 110 Modern Mechanix To avoid mixing up black and white "spotting" paints each time a print is retouched, mix up various color tones and deposit on old glass plates from which the gelatin has been removed. File each glass "palette" in a separate film box to protect it against dust. In retouching, se'e't a palette having correct tone and use paint on it to “spot” print. Left—To keep developing solutions at their proper tempera- ture in cold weather, place tank in bucket of warm water. New ideas and timesavers for the amateur picture-taker and darkroom hobbyist that will add professional touch to his photographic work. While chemical bottles of uni- T: form shape and . size look nice on the darkroom shelf, it is better Practice to use containers that are physically dif- ferent so that their contents can be instantly rec- ognized when working in dark- nes. Bottles suitable for de- velopiag and fix- ing solutions are shown in photo- graph at left. To obtain soft focus effects on "still" subjects, rotate a loose wad of No. 000 steel wool before camera lens, An exposute of 2 or 5 seconds is suffi- cient for average indoor pictures. A permanent shelf for supporting 2 or 3 glass funnels is a great timesaver when both developer and hypo are to be filtered at the same time. Space holes so that 2 trays or tanks can be placed side by side. Shelf can be fastened to worktable with a short upright. February, 1938 111

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AMERAS are constructed to be light- tight, and yet in order to make an exposure it is necessary to let light into the camera and onto the film. This requires a special mechanism called the camera shutter. It is so designed that when a release is pressed, it will move, let light into the camera for a moment or so, and then close and protect the film again from the light. As films have been made more sensitive and shorter ex- posures made possible, the design and con- struction of camera shutters has been improved until today there are shutters that split seconds into almost unbelievably small fractions and let light into the camera for just that fractional part of a second. Most of the smaller hand cameras With which we are familiar are fitted with one, or even both, of two types of shutters. : HOW i "un $ This is the popular “Compur” shutter used on many cameras. The leaves which admit light to the negative are shown here partially open. The num- $ bers around the top outer edge represent H fractions of a second: 1 is one second, ? 2, 15 second, 5, 3⁄4 second, etc. H H [4 H The first type is built right next Pi to the lens, or more properly, be- tween the elements of the lens. For this reason it is termed the lens-plane, or more commonly, the "between-the-lens shutter." The other type of shutter is the focal- plane shutter, so named because of its position right in front of the focal plane or the position occupied by the film in the camera. In aspect, the between-the-lens shutter roughly resembles a doughnut. It consists of a cireular metal casing containing the mechanism in such a way that a large circular opening is left in the center. To either end of this opening are attached the cells of the lens, hence the name between-the-lens shutter. The light-tight part of the shutter consists of a set of movable blades or leaves, from three to five to a shutter, which control the length of time that light shall pass through the lens. When closed they overlap tightly and when open they pass out of the central opening into the shutter casing. Early between-the-lens shutters were actuated by a piston working in a cylinder and controlled by an air brake. This type of shutter is quite satisfactory and is still used on large lenses. However, its popularity has recently been over- shadowed by the develop- ment of a newer and more accurate type of shutter of which the Compur is the leading favorite. This shut- ter is'fitted with a strong spring and a train of gears which controls the action of Upper left—The curtain of the focal- plane shutter showing the slots of varied widths. ^ Center— Photographic reproduction showing volume of light projected by lens through a between- lens shutter. Below it is a similar re- production of a focal-plane shutter. Modern Mechanix CAMERA Sj by T. T. Holden shutter leaves. In some instances this mechanism is so finely adjusted that the leaves open and close in 1/500 of a second. In the newer rim-set Compur shutter, there is an additional set of gears providing a built-in self-timer which delays the actuating of the shutter for approximately twelve seconds after its release. The shutter casing also contains another set of much smaller leaves which do not close entirely, but which can be moved to produce circular openings of different sizes. These are the leaves of the iris diaphragm, so named because of the similarity of its action and function to the iris of the eye. It will thus be seen that while the shutter leaves control the length of time that light can enter the camera, the diaphregm leaves control the amount of light that can pass through the lens when the shutter leaves are open. When the between-the-lens shutter is tripped or released the leaves must open from the center, allowing light to pass through that part of the lens first, then through the entire lens, and finally through just the center as the leaves close. Yet to stop the motion of the image moving across the film, the total exposure period, or the time elapsing from the instant the shutter leaves start to open until they close, must not be any greater than the time to which the control dial is set. For instance, if the shutter is set for 1/200 ofa second, the leaves must open and close in that time. It can be seen that a certain percentage of that time will be consumed by the opening and closing of the leaves, so that light will pass through the entire lens for only a portion of the 1/200 part of a second for which it is set. The advantages of the between-the-lens shutter lie in its relatively compact size, its position on the lens, and the ease with which it may be synchronized with Photoflash lamps. The focal plane shutter in its simplest form, as it appears in the Graflex, Speed Graphic and some of the better grade “minia- ture” cameras, consists of a long curtain or roller-blind. Across this curtain are openings or slots of different widths. When the shutter mechanism is released a slot passes across the film at the back of the camera and light en- tering the lens can pass through to the film. If the slot is narrow the length of time it will take to pass across any point on the film will be shorter than when a [Continued on page 132] Back view of a Graflex camera with the back removed to show the focal-plane shut- ter, with one slot visible. Focal-plane shutters are also used on many small cameras of the so-called “candid” type. February, 1938 Ua HUOM sui

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