Popular Science Monthly 1929-05: Vol 114 Iss 5

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Opular “x, CIENCE sen > MONTHLY Founded 1872 5 zz _ Aviation ~ Radio ~Automobiles ~Home Buildi New Ideas: Engineering-Exploration«* The HomeWorkshop ee ee Se ee ee ee ee so ee Ce a ee ces

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Peter McLaren, Champion has Plumb Axes exclusively for more than twent He says: “* edge, blade, and the bal- ance of a Plumb save me one minute in a five- minute chop. OOLS that you are proud to own... that are a Joy to use The Plumb Scout Axe—pro- nounced ‘“Official’’ by he Boy Scouts of America. Axe alone, $1.40; with leather sheath, $1.80. Chopper, years. he keen tapered Here is the test of a nail hammer,—drawing a headless nail. The hardened nipper claws of a Plumb will grip and pull the finest headless brad, not once,—but every time. H. F. 81 model, price $1.50. They come to you with the approval of skilled mechanics, champions and experts every where In the carpenter shop, on the build- ing job, in machine shop and garage, in the woods and on the farm,—every- where, men who demand the most of a tool use Plumb. The Champion Chopper of America, whose reputation rests upon the blade of his axe, uses only Plumb. The Boy Scouts of America adopted the Plumb as the Official Scout Axe. Skilled craftsmen select the Plumb Nail Ham- mer, the Ball Pein, the Hatchet. Experts, champions, mechanics: It takes more than mere tempering and forging and shaping a handle to win their approval. And Plumb gives more: A tool that is scientifically designed for its par- ticular job; a tool that is balanced till it works like a part of your arm; hatchets and axes of specially selected steel, hardened and tempered to hold a shaving edge. Nail hammers that drive a nail accurately or draw the slimmest, head- less brad; ball peins that add power to your blows ...or that you can control on finer work. Every tool equipped with that éxclusive Plumb patent—the Take-Up Wedge which tightens a handle, when DOUBLE LIFE B | mers Hatch Hammers Hatchets Files Sledges Axes The razor-keen edge of a Plumb Hatchet “bitesin”; cuts fast and accurately ; saves your strength; gets work done. No. 2962, $1.60, it loosens, just by a turn of the screy, Finished with rust-proof Black Head and stain-proof Red Handle—read for a lifetime of service. It is the extra value that won leader. ship for Plumb,—those added touche in a tool that make it a joy to use, Your hardware merchant is a tool expert. Get his advice about the Plumb Tools best fitted for your work. Fayette R. Plumb, Inc., Phila., U.S.A. For peining the smallest rivet, or etriking the hardest blow, the balance of a Plumb Bal! Pein controls your stroke. H.¥F’. 375, 144 Ib. model, $1.30. Other models in proportion. All prices slightly higherin Far West and Canada. —

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Hatchet ves your 2, $1.60, ne screy, ack Head n leader. touches ' to use, iS a tool out the ur work, 9 U.S.A. POPULAR SCIENCE MONTHLY — the Adsl a the Norable =, gregate—observe the overwhelming preference for Cadillac and La Salle. The famous, the socially prominent, the most sophisticated judges of what is best in motor=cars, turn invariably and inevitably to the two most celebrated and sophisticated cars on the streets of the world. g De luxe F isher and F leetwood coachwork render Cadillac and La Salle the most luxurious motoring which the owner s highest ambition can attain. CADILLAC-LaSAgaae Cadillac Motor Car Company—Division of General Motors—Detroit, Mich. — Oshawa, Can.

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POPULAR SCIENCE MONTHLY May, 192 WHAT IS NEW THIS MONTH aia Table of Contents for May LEADING ARTICLES 7 Astronomy Puttine Ligutninc To WorK . . By Robert E. Martin 17 very | on _— . benny “oye . 47 Why engineers spent $75,000 to take one . photograph Wall Boar 1 servatory Built Out of P EcuipsE TO CHECK EINSTEIN. . . By George Lee Dowd, Jr. 21 Astronomers Say the Moon is Brown: . What astronomers may learn from the next solar spectacle Mars, Green. 58 SrRANDED—SEVEN Mites Up! . . By Alden P. Armagnac 22 Designs Great Telescope \ Mirror Like A veteran Air Corps pilot tells of his biggest thrills Honeycomb . 66 War Gas Ficuts Peace-Tme Fors. . . . By Alfred P. Reck 24 Queer jobs that Uncle Sam's chemists are finding for trench poisons Automobiles A Biecer Ditcu THAN THE PANAMA By H.C. Davis 25 Hanging by an Eyelash! . 34 Facts everyone wants to know about the proposed Nicaragua canal Women Drivers Have More Acci- I Am Learnine To Be a Fiver—PartIll. . By Larry Brent 26 dents, Survey Shows. 56 A gréenhorn pilot tells what his first forced landing feels like ~ a “y Extra Wheel If a Tire Pray Tac with Dynamite! . . . . . . By Edwin Ketchum 29 Pg ate al Loses Power in Damp - How experts are seeking a “‘foolproof*’ explosive Weather. .. 58 Do Birps Fy sy Rapio Compass? . By Michel Mok 30 Lock for Emergency Brake to Pre- Why migrating flocks don't lose their way | vent Runaways. 58 Tue Man Wuo Mave Rapio Tatk . By Frank Parker Stockbridge 32 | Odd ‘Flivver™ Craft Rides on Land The romantic story of Lee De Forest or Water ; 67 Maxine New Maps oF THE SEA 37 Leaping Car Lands on Another . 70 Perils of the hydrographic engineers How to Check Ignition Timing . 88 How Human Motes Die River TvuseEs 39 An Automatic Light . 88 A picture story of the marvels of subway construction Valve Adjusting Tool 88 X-Rays Trap Art CoUNTERFEITERS By John E. Lodge 42 Spring Compressor 88 How science can tell a fake from a genuine “old master” A Simple Hood Protector 88 Tue Reau Fatruers or Fuigut—Part V. . By John R. McMahon 48 | apc gg foran Idea. . 88 How the Wrights, idols of Europe, first “‘cashed in” on their plane | ools to Keep Your Auto in Repair 163 SrraNGe Eyes Toat NEVER SLEEP . By Arthur A. Stuart 51 | a Latest marvels of automatic machines that “‘see’’ and almost think Aviation STEAMER Carries A MILE oF Cars . 53 4 Flyi . . Details of an amazing ocean craft that s swallows a whole freight train — — pod aang ry : o Called ** Fool-Proof”’ 40 Model Propeller Pulls 15 Pounds 40 SPECIAL FEATURES New 20-Passenger Air Liner __. 40 Electric Wire Aids Wind Tunnel Cover DEsIGn . By Herbert Paus Tests. 40 Goop InvestmMENTs Can Br Misrits By Wallace Ames 4 Airplane-Dirigible Hybrid for Britain 41 Counsel from the financial editor egy s Bhadow = the Sands. 41 Tue Facts on House InsutatTion . 12 New rb senna _— + ,- Housebuilding tips from the Popular Science Institute of Standards ka, his een a licen 4] Our Reapers Say. . 14 yea —" Autogiros for A 41 Guimpses oF MEN IN THE Pusuic Eve . 20 apg ‘Sek Manet 41 Interesting views of unusual people Radio Lights the Airport. 41 Back or THE Montn’s News. ; By Karl Vooght 44 How Airplane Carrier Crews Keep Where latest achievements fit into the picture of progress Fit 55 Hitcutne PHonoGraPH To Rapio By Alfred P. Lane 62 | Three Men Have Wild Ride in Runa- How to connect an electrical pick-up , | way Balloon . . .. . . 55 UNSCRAMBLING THE Rapio Hasu. . By John Carr 65 | Students Now “Fly” without Leav- Facts about interference every fan should know ing Ground 71 Comrort Bextnp Brick WALLs . By William Dewey Foster 74 Plane’s Siren Switches On Airport Building charm and durability into an economical home Lights! . 72 DuP.icaTING AN ANTIQUE MIRROR . By Frederick J. Bryant 78 New Biplane Goes the Limit in Wing How to make a beautiful walnut replica at small cost Stagger . . 72 Bowts Mabe witH A HamMMER By Edward Thatcher 79 | a — is w rights he Pj 138 Simple directions for oe attractive piec es of copper and brass | ~~ hho ecome of the Pioneer 161 EpirorRiaAls . . . * wa 82. | : ~ ee + + Wuen Vatves Get OvurorSrer _ By y Martin Bunn 84 . . Gus, the auto mechanic, tells the secret of efficient timing E ngineering Tue “Ten THousanptH” Touch . . ' By Henry Simon 94 | Highest Dam in the World 44 Precision hints for the man behind the mic rometer - @ 100-Story Skyscrapers? 47 May, 1929, Vol. 114, No.5. Popular Science Monthly is published month- United States, its possessions, and Canada, $2.50; foreign countries, $3. The at 250 Fourth Avenue, New York, N. Ls pe the ae tots. lar Science Publishing ‘o., Inc. Entered as second-class matte at the Post Office at New York under the act of March 3, 1879: pos. 2, 10%. entry as second-class matter at Careaae. Illinois. Entered as second-class matter at ag) .s = apart Canada. Printed in U. 8S. A. Copyright, 1929, y S Publishing Co., Inc. Single copy, 25 cents. Yearly su A 2. to contents of this magazine must not be reprinted without permission. senting in its editorial columns memerens stories of new products of —_ ied Popu oo not underwrite the business met of the individuals or concerns pr ucing them. The use of ~ wey Science Monthly articles for stock-selling President and Treasurer; R. C. Wilson, Vice-President; lar Science Monthl schemes is never — oO. In pre- B. Capen, . Cole, Secretary.

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COO Om SO tl i Drawing Water Power from Scotch ® Golf Club Picks Up the Ball. May, 1929 POPULAR SCIENCE MONTHLY nds . 66 Nera 0 Locomotive Could Light - oye Aqueduct Is Bored through Italian Alps . - os 70 Exceptional People t Engineer and Adventurer . 20 cont You Can Wear Either Side Out . . 57 Africa Hunter Brings ‘Em Home on Motorcycle . 58 Artist Weaves Portraits from Human Hair . 59 Dare-Devil Fireman Dives 85 Feet into Net . Sok So Magician of Chemistry . 129 Father of the Skyscraper 130 He Makes the Camera Lie 131 Health and aaa Men and Microbes a . 44 Siftinga CitysSmoke . . . . 47 No Sterilization by Radio... 54 Advocates Prohibition of Teeth- De- caying Food é .-« «© ee Cave Children Had Rickets » » ew Me Finds Tracing Cloth Acts Like “Health Glass”... ; More Lime, Fewer Divi orces, De- clares Dietitian . ;. Skipping Heartbeat Not ‘Always Danger Sign... . . . Ti Laboratory Discoveries Sugar from Flowers and Medicine from Sugar . 46 Fishless ‘Cod Liver” Oil Made from Yeast. . 54 Three Hundred Times as Sweet as ee ee ee ee. Nature Bringing Dinosaurs to Life . . . 38 How Insects See Us . 46 Our Best a Stories Are W rong, Says Expe 57 Trees Fed | ; Millions of Micro- scopic Slaves. 67 Frogs Can Learn a Simple Problem inGeometry. . . . 69 He Does All the Housework . . 70 New Devices for the Home Space-Saving Bed Hides in Table 76 Electric Clipper Trims Hedges . . 76 Snips End Offan Egg . . . . %6 Novel Can Opener.’ 76 Measuring Kit Serves Many Needs. 76 | Locks Windows Open or Shut . . 76 Spot-Remover Set for re | Stains. vj Electricity Dries the Laundry eS | Dishwasher Built into a Faucet. . 77 New Floor Polishing Machine . . 77 A “Suitcase” forLaundry . . . 17 Flower Holder Combined with —— « ££ 2 o's « So New Processes and Inventions “Wishbone” Tubes Detect Ap- proaching Vessels. 54 New Grain Elevator W eighs Car- goes Automatically : 55 A Substitute for the Bulky Golf Bag. 59 4 Helps You Pick a Cinder Out of Your Eye. Dual Control for Piano ‘Stops ‘Pu- pil’s Mistakes . . Novel Stirrup Clamp Aids in Bat- tery Repairs. . Automatic Torch Cuts Steel Like a JigSaw . Two Ears Now Can Listen at One Telephone ; , New Red Dye from Cactus. Making a Telephone Talk through a a Loudspeaker. . Track Coach Tnvents New Toe-Hold for Sprinters. . Amazing New Fireproof Lumber Promises Safer Homes Photography Heartbeats in Movies . Onion’s Light Photographed . Radio Your Newspaper by Radio Talk to Byrd from Panama . Trouble-Shooting with Phones . Regeneration and Quality The Right Grid Leak. AB C’s of Radio. . Fugitive Trapped by Long Distance Radio Photo , Radio Brakemen for Trains . Ships Making Submarines Safer. Mothering a Brood of Twelve Sub- marines . Larger and Faster Liners to Ply the Atlantic . Extension Davits to Aid in Lifeboat Launching “ Unusual Facts and Ideas Strange Bridges the World Over Watering the World's Crops Urge 24-Hour Clocks ; How Much Do You Know about Electricity? ; : Where Our Energy Goes Mower Harvests Fodder from Sea Bottom ; The Air Above Your Home Is Yours, Say Experts Italy Originator of Ice Cream? |. Blades Cost Shavers $38,000,000 a Year . 5 Pictures in Wood Etched by Sand . 523 Chrysanthemums Bloom on a Single Stem... Curious waren House Built by Nature : Its Front Door Is a Tunnel Bullfrog Army to Fight ae Mosquitoes : *Skinny”” Men Smartest, College Tests Show . They're Taking the Chill Out of Ice Cream . Millions of Reptiles Killed for Leather ee re a ee Curious ‘“‘Log House” Built of Drainpipes ‘ Trees Worth Millions Do You Know a “ Decibel?’ ’ It’ ie New Unit . Lights Rout Two Enemies of Fruits and Plants : | Produces Shapely Pickles 59 Amateur Carpenters Build Church in 60 60 66 66 68 68 69 70 44 59 64 64 64+ 64 66 70 35 60 4 5 Preparing Concrete for Paint a Day 61 Parlor Baseball Played with Tiddle- dywinks . . 61 682,308 Bird Immigrants. 61 Diet of Milk Makes Worms Alluring to Fishes. 67 Demand for Sawdust Fuel Causes a Shortage. 67 Reads Name of Explorer on Mystery Rock 68 Cordon of Petunia Vines Guards Against Fires. 68 A Cupful of This Poison Could Wipe Out a City . 68 College Course in Pistols and Blood- hounds . 69 Tennis Court 400 Years Old, “Still in Use 69 Altar 3, 500 Years Old Is Unearthed in Palestine oF 71 Beebe Angles for Strange Fish with Radium Bait. 72 Cement Helps Put Out Oil Well Fire. 73 Would Blast Arctic Ice to Keep Us All Cool... 73 Tail Lamps for Elephants the Law in Ceylon . 73 Milk Now Delivered in n Handy Paper Bottles ; 73 “Average Inv ventor” Begins ‘His Work at 25 . . 151 Research Two Miles High . 154 A Strange “‘Death Valley”’ . 160 The Fiddle-Maker’s Secret . 162 For the Home Owner Varnishing Your Front Door. 90 Substitute for Garden Hose Washer 102 Renewing Floors Overnight . . 104 Testing Butter in the Home . 109 Drain for Back Yard... 118 Repairing Shingled Roofs That Leak 119 Hints for the Mechanic Spiders Set Up Work in Lathe . . 96 How to Make a Small Arbor with Square Shoulder 96 Three Ways to Reset a Tailstock . 96 A 1/40,000-Inch Thickness Test with Simple Tools 96 Old Bill Says—__.. 96 A Finishing Tool for Steel or Bronze 116 Revolving Centers for Pipe in Lathe 116 How to Make an Old Style Tool Post More Rigid . . » « Spark Test for Ground Holes . 128 Ideas for the Handy Man A Model Plane for Long Flights How to Cast Concrete Seats A Dresser for Small Homes . Drilling Holes in Glass... How I Built a Portable Workbench for Use in a Small Apartment These Handkerchiefs Can Fly Pins Prevent Bench Drawer from Falling : Blueprints for Your Home Work- shop . Modernistic Smoking Stand. . Strong Joints Made with Clamp Nails. . Old Gun Converted into Floor Lamp Table Extension Aids in Perspective Drafting . Making an Interchangeable. Screw- driver Set. ‘ Cleaning Oily Shop Floors Striping with Lacquer 80 86 92 98 . 100 . 102 102 . 106 108 110 lll 111 . 112 . 112 . 114 . 114

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THIS VALUABLE INVESTMENT GUIDE, just off the press, tells the story of successful invest- ments backed by income- producing city buildings. OUSANDS of In- vestors who desire safety of principal first, and a lib- eral yield second, have read our book each year. This new edition describes how surplus funds may be invested in sound, 612% First Mortgage Bonds .. . as well as in other types of securities earning in many instances higher returns. It also explains the sound security of income-produc- ing city buildings and the numerous safeguards devel- oped during our 56 years of experience for the protec- tion of investors. This latest edition “Fifty-Six Years of Investment Service” may be had for the asking. Return the form below for your copy. Tue F H.Smiti Co Investment Securities — Founded 1873 Smith Bldg., Washington, D. C. Branch offices in New York and other Cities POPULAR SCIENCE MONTHLY May, 19% For thirty-five years Amos Trevor had been with the firm, rising from a minor clerical position to a post of considerable importance and responsibility. Thirty- five years continuously on the job... except for the orthodox two-weeks’ vaca- tion each August ...so when Amos Trevor reached his sixtieth birthday he decided that the world owed him a perma- nent vacation. And why not? Amos Trevor was a widower. One by one his three children had married and settled in homes of their own. His two sons were well-established in business and his daughter was the wife of a prominent young physician. Amos was free of financial responsibilities, ex- cept to provide for himself. For this pur- pose he had the income from $100,000 which he had accumulated during his business life. So Amos Trevor retired. * * Ok Amos Trevor, Jr., the older son, had chosen a life insurance career, at which he was very successful. He was studious and had come to be regarded as one of the best informed life insurance men in the city. He was conscientious and enjoyed the reputation of considering the interests of his clients first. He had a likable person- ality; people enjoyed doing business with him; his contacts were of the best. He was aggressive, but not objectionably so. He was making friends and making money; he was a success. * ¥ * Robert Trevor, the younger son, had also engaged in a professional career— advertising. After serving an apprentice- ship in one of the larger agencies he had gone into business for himself. At first he obtained a few small accounts, did most of the work himself, had a small overhead, did not require much capital, and was showing a snug profit each year. The accounts served by Robert Trevor were growing. Their merchandising plans were sound, their advertising well plan- ned, and they were benefiting from the prolonged era of prosperity. With just the accounts that Robert now had it was evident that his business would grow and that his capital requirements would in- crease. For a small, newly organized agency, Trevor, Inc.. enjoyed a fine repu- tation. His work had gained considerable attention and opportunities to increase his list of accounts were beginning to occur. All signs pointed to a large adver- tising business, requiring considerable capital. But just at present Robert Trevor was making more money than he needed for family expenses and to run his business, so he, too, was investing in securities. Good INVESTMENTS Can Be Misfits By WALLACE AMES, Financial Editor | Note the situation of the three Trevors, Amos, Sr. retired, with no outside fin | cial responsibilities; with ten, fifteen o more good years ahead of him. He had accumulated comfortable financial means, In planning his investments his chief need was income. He had no income ey from his investments. To participate ig life’s comforts his aim was to obtain the maximum income, safely, from securities, His children were doing well, there was no need to increase his wealth so as to leaye a greater inheritance for them. Amos, Jr. was in a line of business that would never require much capital. Aj. ready he had a considerable income in renewal commissions; he was writing a larger volume of insurance each year; the most productive years of his business life were immediately ahead. He was not dependent upon income from his invest. | ments—in fact, he was reinvesting all of it, as well as a portion of his commission income. In planning his investments, Amos, Jr. was in a position to seek in. crease of principal so that in later years he would have the greatest obtainable sum on which to retire. Robert Trevor was confronted with a different problem than either his father's or brother's. The capital requirements-of his business might increase at any time— on a moment's notice. And a call for more capital meant an opportunity to make more money. He should be ready when the call came. In planning his invest- ments, Robert’ s chief need was availability. * * Amos Trevor's sixtieth birthday, the day of his retirement, was an occasion on which the family got together. Naturally the subject of investments was the chief topic of conversation. ““How have you invested your money, dad?” inquired Amos, Jr. **T:have distributed it over a list of near- ly thirty common stocks,”’ was the reply. ‘*“Common stocks!” exclaimed Junior, with some surprise. “Not the kind you are thinking of,” his father assured him. “In the first place, I have spread the risk, with only about $3,000 invested in the stock of any one company. In the second place, I have selected only the soundest of companies in which to make my investments. They are all on a dividend basis and all of them are earning much more than they are paying out in dividends. Stocks of com- panies I have selected should advance materially in market value during the next few years. Their dividend yield hardly averages 5% on the price I paid, but I stand to increase my principal mater- ially.” (Continued on page 5) — May, mawuwrieermwreomoH ms”

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T years ainable with a ather’s ents-of time— r more make ’ when invest- vbility. y, the ion on urally chief oney, near- reply. inior, + of,” first only f any have anies They them are :om- ance next rdly ut [ iter- ge 5) May, 1929 ———— Good Investments Can Be Misfits (Continued from page 4) “Spreading the risk, as you say, is a sound plan. My insurance experience has taught me that,’’ said Amos, Jr. “But my contact with the management of in- surance companies has taught me more. It has taught me that gilt-edged bonds are the best investment. } If a security isn’t good enough for the insurance com- y it isn’t good enough for me. That has been my motto from the time I made my first investment. True, my bonds have not increased materially in value. And their income yield is small, compared to what some people tell me they get on their investments. But my money is safe and the safety of several thousands of dollars is far more important than a few dollars more or less of income. Further- more, there is always a ready market for my bonds, at close to what I paid for them. They may not go up so high as your common stocks, but neither will they decline drastically in value. I am playing just as safe as I know how, which [amsure will pay out best in the long run.” You are right and you are wrong,” broke in Robert Trevor, who had some ideas himself on good and bad invest- ments. “With all due respect for dad’s greater experience, I am like you, Junior, old-fashioned enough to prefer conserva- tive bonds to speculative stocks. But from what you say I suspect I am getting considerably more income from my in- vestments than you, and my investments are safe, too. What is your average return on your bonds?” “Slightly under 5%,” answered Amos, Jr. “Well, 'm getting nearly 6% and if you take the trouble to look over my list I think you will agree that every security on it is safe.” Robert made a list of securities he held. It included several public utility, indus- trial and foreign bonds of a class that an investment banker would loosely class as second grade. They were good bonds, but for one reason or another not up to in- surance company requirements. They offered a reasonable degree of safety, but were not gilt-edged security. A few pre- ferred stocks on the list were subject to the same description. Naturally, Robert's investments paid a higher income return than Junior’s. “What’s the market in these securities of yours, Robert?” asked Junior. “I sus- pect there is a wide difference between the bid and the asked price on most or all of them. If you wanted to sell quickly I'll bet you might have to take a loss, and on some of your holdings you probably couldn’t get an immediate bid at all. What will your bank loan you on these securities? The amount you can borrow on them is one reliable test on how good your investments are. “Now I can borrow 80% of the face value of my securities any time and I can sell out just as quickly as I give the orders. Both you and father would do better if you would put your money in such gilt- edged bonds that I have.”’ * * * The arguments (Continued on pag 6) | POPULAR SCIENCE MONTHLY 5 ADVICE to HUSBANDS whose wives are careless about money By a Husband derstands the value of money. When she goes shopping, she usually comes back without a cent. I am not complaining — far from it. Helen is a wonderful wife and awonderful housekeeper. But frankly, I don’t believe she real- izes how fast the dollars slip through her fingers. I often thought, “What would become of us if we didn’t get a little farther ahead financially? And what on earth would become of Helen and the children if any- thing ever happened to me?” One day I told my worries to a friend. He listened carefully — asked questions. Then e began to talk. I OFTEN wonder if my wife un- How to end money worrics “Frank,” he said, “you don’t want to pay rent all your life. You hope to own your own home some day. And you want to quit work sometime, don’t you?” I nodded. “Then do this. Write to the Phoenix Mutual in Hartford and ask them to send you a copy of a little book they have. It’s called ‘How to Get the Things You Want’ and it tells how you can get rid of a lot of those money worries that are bothering you.” I followed my friend’s advice. In a day or two I received a copy of one of the most interesting little books I have ever read. It explained how I could end - my biggest money worries by simply rearranging my financial life slightly. It described a plan, recently perfected by financial experts—a plan which would enable me to insure a comfortable future for myself and family. It also showed me that our financial trouble was not due to my wife’s care- lessness. It was due to my own ignorance of a few simple financial rules. Send for the facts This story is typical. The book, “How FREE BUDGET BOOK If you request it in the coupon below, you will receive without cost a valuable 32-page Budget Book called“‘The Businessof Running a Home.” This Budget Book furnishes you with conven- ient blanks for keeping a simple record of your major expenses and for planning your expendi- tures in advance. It will also enable you to determine: How much rent you can safely pay How to live within your income Howto avoid common difficulties in budgeting How to itemize your expenses How to cut down expenses How to spend wisely How to tighten up financial leaks How much you should save—and other valuable information Several thousand copies of this Budget Book have been sold for 25c a copy. But now, as a special offer, readers of this magazine may obtain a free copy by mailing the coupon below. to Get the Things You Want,” tells how you can become financially inde- pendent—how you can provide an in- come to retire on—how you can do many other things which you may have felt were beyond the reach of your income. The plan it describes is backed by one of the oldest, most conservative in- stitutions in this country. The minute you read about it you will realize why it works. No obligation. Send for your copy of the free book now. @) PHOENTX. MUTUAL LIFE INSURANCE COMPANY Home Office: Hartford, Conn. Copyright 1929, P. M. L. I. Co. Virst Policy issued 1851 Name | PHOENIX MUTUAL LIFE INSURANCE CO., 431 Elm St., Hartford, Conn. | Send me by mail, without obligation, the booklet or booklets I have checked 0 “How to Get THE THINGS YOU WANT.” 0 Bupcet Book. Date of Birth__ Business Address City Home Address. State. ae

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Retire in | 5 years on your Present living Budget by investing in safe First Mortgage Bonds Follow the definite plan given in this book, and your financial independence is won. The plan works just as surely, whether you are now earning $1,000 or $100,000 a year. The way is certain—each step plainly indicated and absolutely safe—inde- pendent of luck, business genius or speculation. Every fact has been harvested out of the 48 years’ experience of Cochran & McCluer in the first mortgage invest- ment banking business. The plan is so simple, anyone can understand it—so definite anyone can followit—and so certain, noonecan fail. In addition to the Financial Independ- ence Plan and the unique budget schedule, the book gives suggestions that enable you to enjoy more of the good things of life, both while build- ing your independent fortune and after you have attained it. We invite the most skeptical to read this plain, straightforward, interesting Send coupon. We employ no sales- men, therefore none will call. ; Cochran & McCluer Co. | l 46 N. Dearborn St., Chicago, Ill. 4 Please send me, without obligation, # ° your book, “How To Retire In g i /) 15 Years.” 5 i z SE ECC Ee ee eee i a SS Ee ae ee ' | ie ok ceadenatl MR ticecces : Cochran &MCluer Co, Eatablished 1881—Never a loss to any investor. 46 North Dearborn Street, CHICAGO POPULAR SCIENCE MONTHLY q ADVICE IN BUILDING Popular Science Institute Tells How to Cut 30% Off Your Fuel Bill by Insulating An insulated house is warm in winter, cool in summer and costs one-quarter to one-third less to heat than a similar house without insulation. Before you build or modernize your present home, you will want to have information on insulation. A 24-page booklet, INSULATION IN BUILDING CONSTRUCTION, gives ac- tual facts and figures as to what insulation will accomplish, tells where it is of greatest value, describes the principal insulating materials and shows particular methods of application. The Engineers of The Institute have pre- pared this booklet which contains data secured from thousands of architects and builders, as well as University laboratories and Govern- ment bureaus. Price 25 cents. Popular Science Institute, 248 Fourth Ave., New York, Good Investments Can Be Misfits (Continued from page 5) of Amos, Jr. sounded convincing. Robert was convincing, too. So was their father. All three had given considerable thought to their investment plans; all of them had reasoned out their preferences. But all three were wrong in their conclusions. Each had invested in securities poorly suited to his particular requirements. Amos, Sr. needed income; he invested for future increase in principal. Amos, Jr. should have invested for principal gain; he had invested for marketability and super safety. Robert’s situation was such that he ought to have invested in liquid, marketable securities; he had in- vested for safety and income at the ex- pense of marketability. This, in turn, suggests two rules to follow: 1. Establish your connections with some reputable in- vestment banking firm and be guided by their advice. 2. Familiarize your in- vestment banker with your circumstances to guide him in giving you advice. To Help You Get Ahead T= Booklets listed below will help every family in laying out a financial plan. They will be sent on request. ‘*How to Build an Independent Income”’ is the title of a new booklet by the F. H. Smith Company which explains conclusively how people of moderate means may obtain financial prosperity. *‘55 Years of Investment Serv- ice”’ describes the history of progress of the F. H. Smith Company as well as making an attractive suggestion in first mortgage real estate bonds. May be obtained by addressing the home office of The F. H. Smith Company, Smith Building, Washington, D. C. The House Behind the Bonds reminds the investor of the importance, not only of studying the investment, but of checking up the banker who offers it. Address: Fidelity Bond & Mort- gage Co., 1188 New York Life Building, Chi- cago, Ill. ‘**The Investment Trust from the Inves- tor’s Viewpoint,’’ presents an explanation of this form of investment in easily understood terms, illustrated with some interesting examples of how the general investment trust will help the man with $100 or more to get ahead. Pub- lished for free distribution by United States Fis- cal Corporation, 50 Broadway, New York. Ask them for Booklet IT. How to Retire in Fifteen Years is the story of a safe, sure and definite method of establish- ing an estate and building an independent in- come which will support you the rest of your life on the basis of your present living budget. Write for the booklet to Cochran & McCluer Company, 46 North Dearborn St., Chicago, Ill. How to Get the Things You Want tells how you Can use insurance as an active part of your program for getting ahead financially. Phoenix Mutual Life Insurance Company, 328 Elm Street, Hartford, Conn., will send you this booklet on request. The Guaranteed Way to Financial Inde- pendence tells how a definite monthly savings plan will bring you financial independence. Write for this booklet to Investors Syndicate, 100 North Seventh Street, Minneapolis, Minn. The Making of a Good Investment tells how 614% can be made on investment in First Mortgage Bonds in units of $50, $100, $250, $500 and $1000; how the bonds are protected and how simple it is to purchase them. For a copy of this booklet address United States Mortgage Bond Company, Limited, Detroit, Michigan. Invest $9.45 | Monthly. , .| THE modest sum of $9.45 will accumulate for you the substantial amount of $1,500 in 120 months. Our uncon- ditional GUARANTEE is that upon completion of our plan you get not only every dollar invested but interest COM. POUNDED. Send for our booklet, ‘‘The Guaranteed Way to Financial Independence,” also our financial statement showing resources of over $25,000,000. INVESTORS SYNDICATE| — Established 1894 HOME OFFICE: $ MINNEAPOLIS, MINN. New York Office: 17 East 42nd Street Offices in 51 Principal Cities sy Mone not Uneasy Money Your surplus capital, invested in Fidelity 6% First Mortgage Real Estate Bonds pays dividends two ways—semi-an- nually, in the form of interest cou- pons and daily, in peace of mind. Money invested less safely is often “uneasy money” and yields a return that does not begin to compensate for the mental strain it causes. Mail Fidelity Bonds are conserva- tive First Mortgages on new, Coupon —_—iscome produciag peug for latest i eechy ogame offerings =o for latest I BOND * MORTGAGE ry J.U. MENTEER . President « INCORPORATED 195 660 Chemical Bldg., St. Louis 1188 New York Life Bidg. Chicago 378 Colorado Nat’l Bank Bldg., Denver MAIL COUPON TO NEAREST BRANCH Fidelity Bond and Mortgage Co. Send me, without obligation, list of our latest issues. Also, your book- et, “The House Behind the Bonds.” Name Address City State. May: ] Bro of ( SoU

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1CH May, 1929 POPULAR SCIENCE MONTHLY ll Sound can be controlled anywhere Modern science makes it possible to regulate sound, but only Johns-Manville has experience sufficient to cope with every problem of excessive noise or poor acoustics “ oise by two-thirds” writes Edward E. Rage Hoare ent of the First National Bank of Chicago, after installation of Johns-Manville Office-quieting Treatment. For yeats Johns-Manville Acoustical Treatment has been used to provide correct acoustics in theatres, churches, and other auditoriums. XCESSIVE noise, or poor acous- tics, is due to uncontrolled sound. For years we have studied sound, have invented devices for measuring, or even photographing this invisible force, and have perfected means of harnessing it. As a result, J-M acous- tical engineers are the only group of men in this country, working com- mercially, who have any complete, comprehensive understanding of sound control. Noise is costly in business establish- ments, is annoying everywhere. To tolerate noise has now become old fashioned. The Johns-Manville method of sound-quieting and acoustical con- trol is neither experimental nor theo- retical. It will often eliminate as much as 80%. How J-M Halts Sound Waves The control of sound may be for the purpose of — g disturbing noise, or it may be concerned with the cor- rection of acoustics, as in auditoriums or other public rooms. The plaster, cement, glass, and sheet metal so common in present day con- struction have almost no ability to absorb sound. A sound wave, even though invisible, will bounce about a room as literally as a rubber ball might. The result is that irritating and dis- turbing confusion of sound which we generally describe as noise. Decorative Schemes Unaffected Johns-Manville acoustical experts, by the use of special finishes, produce a surface which will absorb as much as 80% of the sound in a room, and do so without affecting the architectural or decorative scheme. In your own office, or factory, in your church or lodge room, in a hos- pital in which you are interested, any- where, in fact, Johns-Manville can ban- ish excessive noise and bring about an amazing degree of quietness and calm. Industrial buyers and home owners the country over know Johns-Manville Asbestos products~such as Asbestos Shingles and Built-up Roofing, Heat and Cold Insulations, Packings, Brake Linings, and scores of other products. Yet in none of these is there more careful effort than in the really marvel- ous science of sound control. The ceiling of this corridor at the Harper Hospital, Detroit, Mich. (Albert Kahn, Architect) blots out disturbing sounds because it is covered with Johns- nville Sound Control Material which silences reverberations and echoes. M Jo SOUND-ABSORBING TREATMENT : s-Manville \ This picture is a photograph of sound. By such Johns-Manville methods are auditoriums analyzed in order to determine where and what acoustical treatment is desirable. Our own photographing devices make it possible to take pictures showing the movement of sound waves at their origin, and during the bounding and interference which results in noise. JOHNS- MANVILLE CORPORATION New York, Chicago, Cleveland, San Francisco, Pleasesend me informatica about the Johns- Manville Method of Scientific Sound Control. Name Company Toronto * (Branches in all large cities) ZW HAYS C-96-5 cm iu endian cin tn aaa

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The Facts Expert Advice Now Made Available to Every Home Builder ““e-’M PUTTING insulation in my new house. I don’t know much about it, but my architect has convinced me that it’s too good a thing to pass up. It is a safe guess that, when it came to putting a furnace or electricity in his home, nobody had to convince this man that it was the thing to do. But, had it not been for >, a an up-to-date and in- ’f Vea sistent architect, he ———-—~~™- et POPULAR SCIENCE MONTHLY on House ” ro Bar -—- ~ would have overlooked one of the best modern aids to home com- fort. Insulation is one of the few real conveniences that are permanent and have no upkeep cost. It pays actual dividends in fuel-saving that soon offset its initial cost. Insulation pays its way by cutting down the annual fuel bill from twenty to forty percent. And it assures comfortable temperature. Insulation By COLLINS P. BLIsg Director of The Popular Science Institute of Standards him to make the decisions It is a wise builder who takes all the professions! suggestions he can get, and yet supplements such jp. formation by finding out for himself exactly what the market has to offer what is most advantageous for his use, and just what the actual returns on the investment are likely to he. The Institute Finds Out HELP the home builder who wants all the facts on insula. tion, Popular Science Institute recently un- dertook a nation-wide survey of the subject. First, it con- sulted 5,000 architects and builders in all parts of the country, obtaining their opinions on insulation in general, their preferences with regard to special ma- terials, and their experience as to the most desirable methods of applica. tion. Then The Institute secured from every manufacturer of insulating mate. rial, university laboratory, and Govern- ment bureau all the data that they had on the subject. The vast amount of in- formation thus gathered was studied and organized by the engineers of the Popular Science Institute. Facts were checked, inaccuracies determined, and finally all the data put into printed form in a way to give the home builder specific, non- technical advice. The result is a twenty-four-page book- let “Insulation in Building Construc- but man has always had to work out schemes for keeping himself warm. He solved the problem of body insulation ages ago, but it took many centuries to evolve a method for preventing heat leakage in his home. Primitive men, with their tents of animal skins or mud huts, as well as our grandfathers with their stone walls some sixteen inches thick, were all work- ing to cut down heat loss. They did not get very far. But in the twentieth cen- tury, real home comfort has_ been achieved. Today the home builder need only apply a‘half inch or so of one of the effective modern insulating materials in roof and walls to make his house a home instead of a mere shelter. In planning house insulation, the home builder may consult an able architect or an experienced contractor. They may offer valuable suggestions, but it is up to Insulation Pays Its Way Te MOST people, house insulation is a vague something that never has had to be used before and need not be used now. Most people know what their dollars invested in an automobile or radio bring, but they have only the haziest idea of what insulation accomplishes. If they knew that, dollar for dollar, insulation pays its way in saving fuel bills, providing a cozy, warm house in winter, a cool house in summer, and uniform room temperature, they would soon include insulation among the prime essentials. Insulation itself is nothing new. Its principles have been applied since earliest times. But the effective and economical insulating materials now designed for house construction have been available only within the last few years. No- body talks about “ putting on insula- tion” when he dons a fur coat or pulls up a woollen blanket, but that is what he is doing. Insulating means stopping heat flow. Fur and wool, with their fibrous texture full of air spaces, are insulators in that they present a barrier through which heat has a hard time traveling. Cotton, silk, and linen, on the other hand, contain few air spaces, and heat can travel quickly through considerable thicknesses of such materials. The body is not able to generate enough heat to keep up with the rapid loss through these materials; therefore they fail to keep one warm. Brings Real Comfort IRDS and animals do not have to worry about insulation for nature has supplied them with it. INSTITUTE BULLETINS and SERVICE AIDS FOR READERS Insulating the Home* List of Approved Tools List of Approved Radio Prod- ucts What the Radio Buyer Should Know* Current Radio Questions Dis- cussed List of Approved Oil Heating Devices Advice on Installing Oil Heat List of Approved Refrigerators Refrigeration for the Home* *Price 25c each tion,” which gives actual jfacts and figures as to what insulation will accomplish, tells when and where in- sulation is of most value, describes the principal insulating materials, and shows particular methods of application. A section of this book- let is devoted to the actual use of insulation in houses already built, and tells just how to go about insu- lating such buildings as well as the correct time to insulate effectively and economically. Another part of the booklet tells about air leakage and its remedies, as distinct frot heat leakage which insulation cof- rects. ; The price of the booklet 3 twenty-five cents. In writing for it or in sending special questions on insulation and other building problems, address Popular Science Institute, 250 Fourth Ave., New York, N. Y.

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May, 1999 On BLISS r Science rds decisions, ilder who "fessional nh get, and such jp. ding out tly what to offer, antageous just what IS On the ely to be. tute ut the home ho wants on insula- r Science ently un- tion-wide " it Con- lilders in ning their ral, their ecial ma- s to the applica- red from ng mate- Govern- they had int of in- died and > Popular checked, inally all in @ way ific, non- ze book- Yonstruc- facts and tion will where in- describes raterials, hods of 1is book- il use of ly built, ut insu- ll as the fectively part of leakage ct from ion Cor- oklet is ting for juestions building Science >, New FOR SCENES IN THE MOVIES POPULAR SCIENCE MONTHLY Romance or reality, movie studios or factories ---there this grainless wood In moving picture studios the strength and lightness of Masonite Presdwood, com- bined with its ability to take any finish, make it the chosen material for set building. In industry the same qualities lower production costs and make manufactured articles better. Perhaps you, too, can use it to advantage. May we send you samples to try? May, 1929 A king’s palace today—a rustic cottage tomorrow. To Mason- ite Presdwood, as used in the leading movie studios, it is all in the day’s work, for so sturdy is this beautiful grainless wood that moving picture producers find they can use the same pieces again and again—in scene after scene. But this versatile actor, Presdwood, plays equally important industrial roles. Today a shipment goes to an automobile body plant to be used in motor truck side panels. Tomorrow a carload is routed to another factory where children’s toys are being turned out by the thousand. In fact, there seems to be no limit to the wide range of uses for this attractive panel- ing material. And alert production managers are continually finding new ways to use it in improving their products or lowering the cost of the articles they manufacture. Unlimited Uses in Industry and Building Presdwood is used for the ceilings of railway passenger coaches, for the backs of theatre seats, in automobile bodies and speed boat decks and hulls. It makes light, strong, splinterless ship- ‘ping containers, decorative folding screens, bass and snare drum shells, table tops, kitchen 13 cabinets and many other fa- miliar objects. In building, it is used for interior paneling, for house and office partitions and for the lining of closets, attics or elevator shafts. It is specified for the surfacing of concrete and masonry forms. And because it is easily sawed or cut and does not split, it is ideal for the man at home who puts up shelving or for the me- chanic who builds a doli house. Eliminates Waste and Expense Since it is free from knots, checks, or cracks, Masonite Presdwood reduces waste and cuts ex- pense to a minimum. And because it is made from natural wood, with no artificial binding material, it cannot possibly harm valuable tools and machinery. New methods and up-to-the-minute materials will bring profits to your business. Masonite Presdwood is wood in its most modern form. Investigate its money saving possibilities. Your request will bring a generous free sample by return mail. MASONITE CORPORATION Sales Offices: Dept. 725 111 W. Washington St. Chicago, Illinois Mills: Laurel, Mississippi TO REPRESENT INLAID FLOORS Aasonite PRESDWOOD MASONITE STRUCTURAL INSULATION R00. U6 PAL Ore. FOR MOTOR TRUCK PANELS ABCCANDY COMPANY FOR PUNCH PRESS OPERATIONS

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Ow Readuy POPULAR SCIENCE MONTHLY

Cee— Etc., Etc. “T)ON’T take too much notice of the growlers whose complaints you publish. They have got bugs, etc.’"—C. S., Dunedin, New Zealand. Otherwise, a Masterpiece! _ E -WISH to make a few comments on cover design of your February issue of Poputar ScIENCE. “We note the very cleanly dressed iron- worker who is apparently unhooking the chain from the column that we imagine has just been set. Where do you find an iron- worker that has as clean a shirt as this fellow has on? “Tf he had to shin the column to loosen the chain why did he climb above the chain to loosen it, and if it was necessary for him to assume the position in which you show him in the picture, what will happen to him when the chain is loosened? His right foot is resting on the chain, and from all appearances when the chain is loosened his right hand will be the only means of support he will have. “He appears to have quite a lot of slack in his hand. If there was that much slack in the chain why was it necessary for him to climb the column to loosen it? The method of slip- ping a chain is very simple—it is very seldom that they stick. You merely slack off on the load line and the chain slides down the col- umn. The hook that he is trying to unloosen is also hooked the wfong way on the chain. “We also note that each beam connection has eight rivets holding it to the column. If eight rivets were necessary at the column why not eight rivets in the beam, the load being equally divided at this point? “We also notice that the tag line, which is laying on top of the ball, was evidently not used in erecting the column or this snarl would have been taken out of it before the load started up. “Trusting that these comments will not be offensive.’"—R. R. C., Pittsburgh, Pa. Jopular

Maybe Einstein Helped” “T THINK a journal like Porvtar § OE Montuiy should publish nothing § proved facts, or else give it as ideas, theort or of that nature. “In the article on guano birds it states th these birds, on one island alone, eat one thé sand tons of fish a day. What I wish to ka is who counts or weighs the fish they eat? “In the same issue it gives a history of John Kenlon’s works. What I want to know is, if he saw the last vestige of his ship sink, how and where they got ropes to frame their cement boat? Also sails sufficient to sail that boat 1,600 miles in sixteen days? “*Well, I may want some other explanations again some time, so I reckon this is enough for this time.”—-F. C. C. C., P. M., Flint, Tex. From the First Skywriter “ APROPOS of your recent article on ‘Sky- writing’ and your reference to me as first skywriter in the world— “The first writing for the Daily Mail, of which you told, was a very nervous experience, as it meant all our future. This also applied to the first writing in America, and as the word I wrote was ‘Hello U. S. A.,’ it would have been rather disastrous if the smoke had stopped —- after the first fow etters! | “The only other occasion I had ‘nerves’ was the day I was married in Los An- geles, when I was called upon to skywrite 100 miles away and was afraid a forced landing might prevent me from getting back. Incidentally, although that was six years ago, I am still very glad I did not have a forced landing.”—Capt. Cyril Turner, Boulogne, Seine, France.

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\ \ TO WORK hy Engineers Spent $75,000 » Make a Single Photograph NGINEERS of a great electrical concern spent $75,000, not long ago, to obtain a single photo- graph. And they considered the money well spent! The picture was of a flash of lightning. To the lay eye it resembled only a jumble of white lines streaking across a black field marked off into scale divisions. Yet the men who made the picture prized it as though it were a crown jewel. That single picture rewarded months of work of hoisting bulky scientific instruments to the top of alonely mountain. A dazzling bolt of white flame that By ROBERT E. MARTIN A magnificent nighttime play of forked lightning about the Woolworth tower in New York City. Sky- scrapers are virtually lightning-proof, for their steel construction drains the electric fire to earth. ACKED in a single lightning bolt is a thousand billion horsepower! In a flash measured in millionths of a second, almost unbelievable energy goes to waste —from sky to earth. This ab- sorbing article tells how engi- neers are piercing the mysteries of Nature’s mighty fireworks, and seeking ways to harness their titanic power for everyday use. Aate Secands ee ee ee eS a | In this $75,000 photograph, Westinghouse engineers made lightning write its own story, telling facts never before known. crashed down upon Chilhowee Mountain, near Chota, Tenn., had been made to write its own autograph. And for the first time science had a record of a lightning bolt’s entire life history—where it struck, its duration, its electrical power, and its effect upon a near-by transmission line. Within the last few months such ex- periments have opened a new chapter in our knowledge of atmospheric electricity, and new possibilities of putting that knowledge to practical use. Now that lightning’s titanic power is known in such familiar terms as an electrician uses to rate a dynamo’s output, that information is being applied to realize long-awaited “lightning-proof” electric transmission lines. Engineers say that these must pre- cede their dream of a super-power system to link whole sections of the country in electrical tie-ups. Indoors and out, newly-developed ma- chines forge bolts of artificial lightning today, They test rods and systems de- signed to ward off Nature’s lightning from buildings and oil tanks; and they double 17

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How lightning is formed. In a squall preceding a thunderstorm, warm and cool air, meeting in turbulent eddies, tear apart molecules of moisture and pile up their electric charges on the clouds. At last an accumu- lated charge leaps to earth in a blinding flash. Thunderstorms often follow courses of rivers and streams. for natural lightning in testing power lines. Tomorrow they may have other revolutionary uses, such as blasting apart atoms to transmute metals. Can Jove’s bolts themselves be har- nessed? Scientists are considering the possibility. In the Swiss Alps a party of bold experimenters are seeking to trap lightning with weird antennas and force it to transform familiar substances into others perhaps new to science. And to practical engineers, the thousands of billions of horsepower that go to waste in every lightning flash are a tempting prize. A bolt is launched every second, they estimate, in one of the 1,800 thunder- storms raging somewhere on earth at all times. VER since Benjamin Franklin drew sparks from a key tied to a kite string and proved that lightning was electricity —in 1752, or thereabouts—experimenters have spent much time and money seek- ing more facts about it that they could put to practical use. POPULAR SCIENCE MONTHLY WARM ASCENDING h AIR Last summer two expeditions of engi- neers fared forth to study and measure lightning’s force, armed with new instru- ments of astounding ability. In the foot- hills of the Allegheny Mountains near Lake Wallenpaupack, Pa., engineers of the General Electric Company made their camp beside a 220,000-volt transmis- sion line—the first line oper- ated at so high a tension ever built in a lightning-in- fested territory. Meanwhile experts of the Westinghouse Electric and Manufacturing Company encamped upon the summit of Chilhowee Mountain, near Chota, Tenn.—said to be one of the stormiest sections in the United States—beside a 154,000-volt transmission line. The purpose of each ex- pedition was to photograph the surge of electric current over a power line struck by May, 19% natural lightning, usi mary new cameras capahled eons what could happen in a millet of 2 — or less, p ilhowee Mountai Westinghouse engineers "4d their automatic camera, a “ inder oscillograph” so sensitie for all its two-hundred- a weight and seven-foot height, that it could record an electric lasting only a ten-millionth of second—the time taken for a hi ‘ powered rifle bullet to tra the thickness of two hairs, “7 N OVERHEAD lightning bolt LA. jarred the clouds as it rocket, ed past the transmission line. The automatic camera whirred, late to disgorge a picture of the 650,000-volt discharge in the power line produced by the flash, It was a $75,000 picture, the one to reward a whole season of expense and labor—but it showed as never before just what happens when lightning threatens powe wires. Meanwhile the General Electrie engineers’ camera, a high-speed cathode-ray machine, had record. ed a phenomenon never befor § measured. In the midst of thunderstorm, a streak of flame from the heavens landed with a deafening crasi: squarely upon the transmission wires! The camera was on the job. When the picture was developed it showed that the camera had recorded a high mark of 2,500,000 volts! The work of these men has made it possible at last to recon- struct a fairly accurate picture of a lightning bolt. One hundred million volts— twenty times the most potent electrical force that man’s mighti- est electrical machines have gen- erated. One hundred thousand amperes—and it takes but half an ampere to light an ordinary elec. tric lamp. A thousand billion horsepower—and all the machines in the United States, from tur- bines to automobiles, and electric motors to locomotives, use less than a billion! That is a picture of a typical lightning bolt, lasting from one to ten millionths of a second. Only by such exact knowledge is it possible to build a power line so proof against lightning that its poles will not ANNUAL NUMBER OF THUNDERSTORMS In the United States thunderstorms are most frequent in the Gulf Coast region and southwestern Colorado. Coast is almost immune. Parts of Florida are hit the hardest. The Pacific

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ry elec. billion achines ym._tur- motors billion! ghtning llionths re is it » proof vill not May, 1929 a “*s¢ inculators break down, nor seals Deukinery connected to it burn if a stray bolt hits it. Such a line is 0 tial if whole states and sections of the county are to be tied together in an ical system. ; ; Now that the power of natural lightning -. known definitely, artificial lightning . be used as well for tests. For years pn! eers have been trying to imitate Nature’s lightning. At Pittsfield, Mass., engineers of the General Electric Com- y announced in 1921 the then unprec- Piented achievement of a million-volt holt. Two years later they were pro- ducing 2,000,000 volts. In 1928, 3,500,000 yolts was obtained; and only last January a 5,000,000-volt bolt crashed between two brass balls in the Pittsfield labora- tory, as the entire power of four whirring dynamos was ‘short-circuited in a single mighty flash. has developed an artificial lightning machine which can be carried from place to place in a truck, to test transmission lines. It is putting to work lightning of hundreds of thousands of volts, that leaps in a blue flash between two spheres of brass. It is the first “portable thunder- storm” ever invented. Other uses for lightning, both man- made and natural, are just around the corner. The Carnegie Institution at Washington, D. C., has developed a 5,000,000-volt machine with which, when suitable vacuum tubes are developed to apply its mighty power, they may blast atoms and transmute metals. Still, man-made machines have yet to approach the electrical pressures manu- factured by Nature. The vivid flashes of a thunderstorm appear in several guises. The familiar forked or “chain lightning,” the deadly variety, is simply an electric spark on a monster scale. “Sheet light- ning” usually is the reflection of distant forked lightning from the clouds, while the rare and often disputed phenomena of “ball lightning” apparently consists of fiery balls that some observers claim to Now the General Electric Company have seen floating through the air during an electrical display. POPULAR SCIENCE MONTHLY A thunderstorm starts as a small cloud, perhaps less than a mile wide, that picks up new clouds and spreads out in a fan- shaped path. It courses across the country at about thirty miles an hour. A person with a speedy car and an ex- pert knowledge of roads could outdistance it. Along the front of the rain-dripping cloud, heated humid air rushes upward as in a chimney, piling the front of the cloud into the typical white bil- lows of a “thunder- head.” A forward-rush- ing wind from the cold descending air in back —the squall that pre- cedes a thunderstorm —meets the updraft in turbulent eddies. That is Nature’s dynamo. The eddies break up molecules of the water -* . million volts of arti- ficial lightning. A spec- tacular laboratory test. vapor in the saturated warm air and sepa- rate their positive and negative electrical charges. Electricity piles up on the clouds until the strain due to a difference in electrical pressure between two clouds, or between one cloud and the earth, breaks down the resistance of the air between. Then a brilliant flash, often a mile long, “Sao % leaps across the gap. Air heated by its Lightning flash near a transmission line. Such a bolt may splinter poles and put circuits out of commission. Using a“ portable thunderstorm” to test a lightning-proof device for a transmission line between Turners Falls and Pittsfield, Mass. The apparatus carried on the truck generates artificial lightning at hundred. of thousands of volts and applies it to the line, imitating effects of a real thunderbolt. A twenty-foot wooden pole “‘ struck’’ by three 19 passage leaps aside to leave a hollow tube of vacuum, into which the compressed air crashes back. The con- cussion is what we know as thunder. The light of a flash reach- es us almost instantaneous- ly, while the noise of thun- der travels at the speed of sound, roughly a thousand feet a second. Thus it is possible to estimate the dis- tance of a lightning flash with a watch or by counting seconds. Every five seconds that elapse between the time of sighting the flash and hearing the thunder represent about a mile of distance. If twenty-five A marvelous camera, the “Norinder oscillograph,’’ used by Westinghouse en- gineers to measure power of natural lightning. It can record an electric dis- charge lasting only one ten-millionth of a second. seconds pass, for in- stance, before the sound is heard, the bolt is five miles away. The rumble of a distant thunder clap is its echo from surrounding clouds. Frequency of thun- derstorms varies ac- | cording to location. Practically unknown in the Arctic region, they are most frequent and violent in the tropics. Southwestern Colorado and the Gulf Coast lead in the United States, while the Pacific Coast is comparatively immune. averages less than one thunderstorm a year, while Tampa, Fla., is shaken by an average of more than ninety. New York City and Chicago weather from thirty to San Francisco fifty a year. Many are the proverbs and supersti- tions concerning lightning. “Lightning never strikes twice in the same place”—there is a good old-timer. But the Eiffel Tower in Paris, to mention one example, has been struck dozens of times. (Continued on page 148)

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POPULAR SCIENCE MONTHLY Glimpses of Men in the Public Kye oe L. S. Buffington, inventor of the skyscraper, receives his first royalty. HEN, a little more than ten years ago, Edward R. Arm- strong first propounded his idea of building a series of great floating airdromes and anchoring them at intervals across the Atlantic to provide way stations for a regular flying service between America and Europe, the public regarded it as a fantastic dream. Aviation experts took the idea more seriously. Armstrong’s words, as consulting engineer in charge of mechanical and chemical experimental development for the Du Pont company, carried authority. Still, realiza- tion of the project was considered a thing of the dim future. Now Armstrong’s conception is about to become a reality. A syndicate of New York financiers has backed the plan with millions. And shortly we may see winged liners flying from New York on a thirty- six-hour schedule across the Atlantic, pausing at 400-mile intervals on huge float- ing airports for fuel and weather reports. Actual construction of the first Armstrong sea- drome is to be started in August. It will be built along lines described pre- viously in PoPuLaR Scrence Monruty inside the Delaware Capes near Cape May. The job should be finished by June or July of next year. The plan is to anchor it at a point midway between New York and Bermuda. But the complete project calls for seven more such ocean airports—a string of eight artificial islands stretching across the sea from our Atlantic coast to the Azores! Armstrong’s career has been a curious crazy quilt of vocations. At one time, he was featured as the strong man in a cir- cus! And this despite the fact that Na- ture, apparently, had meant him to be a physical weakling, When he came into the world at Mount Forest, Ontario, Can- ada, in 1877, he weighed exactly three pounds! The puny baby grew into an undersized and sickly boy. But when he was about eleven, a chance remark by his mother that he would never be as strong as his father determined him to improve his physique. The result was a triumph of will power. When he was nineteen, he was famous for his prodigious feats of strength and his lectures on health. Edward R. Armstrong, inven- tor of floating ocean airdromes. A Great Engineer bestowed upon John Hays Hammond the William Lawrence Saunders medal, the highest award within After about a year of weight-lifting, cable-breaking, and health missionary work, he decided to go in for wrestling. At twenty, he was in a fair way to become the wrestling champion of the world, but his prowess somehow didn’t satisfy him. In Cleveland, Ohio, at the time, he picked up the threads of a rather desul- tory education and took an engineering course, after which he joined a railroad surveying crew. His climb in the engi- neering world was a steady one. Once, however, he turned away from the profession for a_ brief, strange interval. Attend- ing a circus with some friends, he jokingly re- marked that he could easily duplicate all of the tricks performed by the star strong man and teach him a few new ones be- sides. This he did after the show. The strong man being about to quit his job, Armstrong took his place and for two months traveled with the “big top.” Five years of surveying work in the Texas oil fields followed. About that time the Wright brothers developed their first plane and Armstrong took a keen interest in aviation. He experi- mented in building sea- planes, but abandoned this work when he found they were not prac- ticable for long sustained flight. of the World War, Arm- strong joined the Du Pont company. At the beginning and Adventurer HE American In- stitute of Mining and Metallurgical Engineers recently turns waste John Hays Hammond, has wrested riches from the earth. Arthur D. Little, Lejaren Hiller, camera illustrator at work on a model of the Sphinx. its power to confer. The award came as one of the crowning glories of a distin. guished career as an engineer. Hammond's genius has carried him to California, Mexico, Russia, China, Japan and Siberia to open mines, build rail. roads, clear jungles, bridge rivers, level mountains, and construct highways, He is now seventy-four years old. The story of his life is the stuff of which the world’s great romances are made. For he has been not only an engineer, but also an ad- venturer and _ soldier of fortune. In the stirring days that preceded the Boer War in South Africa, for example, Hammond’ activity as a leader in an attempted revolution won him imprisonment in an African cell and a sentence of death! At that time, at the age of forty, he was in the employ of Cecil Rhodes, the “empire builder,”’ in charge of the great gold mines at Johannesburg, and of the development of mineral deposits in Rhodesia. There had been a long series of injustices to the “uitlanders,”’ or for- eigners, who, though bringing brains and capital to the country, were denied a voice in the government. The Johannes- burg mining community deemed the over- throw of “Oom”’ Paul Kruger, president of the Transvaal Republic, the only means of relief. A crisis came about 1895. Plans were laid for a revolt, in which Hammond became one of the leaders. Arms were smuggled in, but delay in their arrival brought on the famous Jameson Raid which resulted in Ham- mond’s arrest and sen- tence to be hanged for high treason. A storm of protest arose through- out the world. After months of negotiation, Hammond was finally released on the payment of $125,000. : After a few years im England, Hammond re- turned to the United States in 1900, and dur- ing the ensuing ten years devoted himself to the development of some of (Continued on page 129) , chemist, into wealth.

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May, 1999 | illustrator the Sphinx. itd came as of a distin. ‘ied - to Ina, Ja n, build mt gles, bridge mountains, highways, venty-four e story of > Stuff of Id’s great lade. For it only an lso an ad. soldier of le stirring ceded the ith Africa, ammond’s der in an ution won ant in an eath! forty, he 10des, the the great nd of the posits in ong series ,”” or for- rains and denied a J ohannes- the over- president the only out 1895. in which aders. delay in famous in Ham- and sen- nged for storm of through- After otiation, | finally payment years in 10nd re- United ind dur- en years to the some of ge 129) , POPULAR SCIENCE MONTHLY How shadows of total and partial eclipse are -pro- duced by the moon as it crosses the sun’s face. This diagram, of course, is not drawn to scale. clipse to Check Einstein Astronomers Journey Halfway Around the World to Study Five-Minute Spectacle, as the Moon Blots the Sun’s Face INSTEIN’S theory of relativity receives a new test in the wilds of Sumatra in the Dutch East Indies on May 9, when leading astronomers of Europe and America study and photo- graph a remarkable five-minute total eclipse of the sun, for which they will have journeyed halfway around the world. The dura- tion of the eclipse, and the fact that this island off the Malay Peninsula lies‘directly in its path, offer an unusual opportunity for scientific observation. The average eclipse lasts only from one to four min- utes, and the longest possible duration of a total eclipse for a single observer is seven minutes and fifty-eight seconds. As the moon passes across the face of the noonday tropical sun, its shadow, a hundred miles wide, will stretch a ribbon of darkness over the central islands of the Philippines, southern Siam, Cochin- China, the Malay Peninsula, and Suma- tra. At different points along the path of this shadow, expeditions from the United States, England, . France, . Ger- . many, and Holland will await its coming. For weeks before, the members of these expeditions will have rehearsed their parts in changing camera plates and checking observations. During the precious minutes of darkness, they will By GEORGE LEE DOWD, JR. Photographs during the eclipse will test Einstein’s theory that the light from a star is bent from its course in passing the sun, so that its apparent position in the heavens is not its real position. work with the speed and efficiency of mechanics changing the tire of a racing auto. If it rains or is cloudy during those five minutes, a quarter of a year of preparation and travel will be lost by the expeditions to Sumatra. That is!and will not see another total eclipse until 1988. During this miniature midnight, the stars in the neighborhood of the sun will be photographed. To test the Einstein theory, the same stars will be photo- graphed again at night. Their positions in the two photographs will be compared. If they appear to be in a different posi- tion in the eclipse photograph, it will indicate that the light rays were bent out of their courses in passing the sun, in accordance with the theory of the famous German scientist. Similar tests, made by British observers in 1919, tended to con- 21 firm the Einstein theory, while those made at the Lick Observa- tory in California during the eclipse of 1922 showed almost the identical displacement of stellar images predicted by him. But some other tests are said to have indicated deviations from his formula, so the expedi- tions are placing tests of the famous theory at the head of their list of experiments. Two other experiments, dur- ing the five-minute eclipse, may result in important new dis- coveries. In one, the effect of a total eclipse upon the transmission of radio waves will be studied. The other will attempt to determine the exact nature of the corona, that mysterious glowi envelope that surrounds the sun an sends its streamers millions of miles into space. URING the 1925 eclipse, visible in the eastern part of the United States, scientists on board the Navy dirigible Los Angeles drew the outline of the corona as seen high in the air. At one time it appeared like a fiery octopus, at another like a box-elder leaf. It is possible that observers in distant Sumatra may dis- cover whether this corona is gaseous, liquid, or solid, and may even determine its chemical composition.

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TUCK inthe air seven miles above the earth. No way to come down until the plane ran out of gas. Through holes the size of a thumb-nail in the lenses of his goggles, Capt. St. Clair Streett, U. S. Army Air Corps, stared at his balky con- trols. He couldn’t shut down the motor! That recent experience was one of a series of thrilling adventures that have befallen this doughty little pilot of Wright Field, at Dayton, Ohio, who has flown an airplane higher than any other man but one. My introduction to him was spectacular. I stood at the gate of the flying field watching a buzzing swarm of planes cavort in the air. “You want to see ‘Billy’ Streett?”’ the officer asked me. “There he goes!” Across the leaden gray afternoon sky blazed a strange apparition—a dazzling ball of fire on the wing tip of a giant bomber. A staccato roar of exhaust echoed in my ears as the aerial shooting star passed. Could the plane be on fire? It came to earth, and Captain Streett hopped out to put my fears at rest. “Flares,” he explained, “for night land- ing. We test them here.” For Captain Streett, as chief of the flying branch of the Air Corps’ Matériel Division, has charge of the testing of new planes and equip- ment. Here is a veteran, at thirty-five, of narrow escapes from death. Once when flames, in mid-air, licked dangerously near POPULAR SCIENCE MONTHLY x fi Viw } (es) “ie tay, Stranded—Seven Miles Up! There they were at the seven-mile ceiling, and the motor wouldn’t slow down! Their oxygen supply was running lower and lower. Minutes seemed like hours. ND that’s a long way from home, The highest photograph ever taken, showing an area of thirty square miles in the vicinity of Dayton, O., from an altitude of more than seven miles. It was snapped by Capt. A. W. Stevens, seen above with his aerial camera, in the plane piloted by Capt. St. Clair Streett (left). On this flight Streett had the hair- raising experience related in this article. the gasoline tanks of a plane he was piloting, he won a fifteen-mile race with them to the nearest landing field. An- other plane somersaulted and pinned him beneath it; he crawled out without a scratch. On one occasion he tore the fabric off a wing in mid-air—and landed safely. For leading the first aerial ex- pedition to Alaska in 1920 he won the when you're touching the icy ceiling in a plane that won’t come down—and breathing from a bottle! Here’s the story of a flyer whose thrillers in the air few pilots can equal. By ALDEN P. ARMAGNAC coveted Distinguished Flying Cross. And, a few weeks ago, he topped off a career of thrills by a flight that earned for him and his companion the altitude record for a plane carrying two men—and very nearly a world’s altitude record for all planes, as well. Seven miles high! Captain Streett had shed his flying togs, and escorted me toa cozy green cottage at the field’s edge— shared by his wife and his year-and-a-half- old boy. His pipe lit, he was telling me of his latest exploit. A boyish, rather slight figure—I thought of the great bomber I had seen him piloting. Brown hair, a close-cropped mustache. It seemed hard to believe that this mild-mannered young man was the aerial adventurer that his record showed. Quite obviously he dis- liked to talk about himself. But the story came out: As of Captain Streett’s, Cap- tain A. W. Stevens—in charge of the Aerial Photographic Unit at Wright Field, and probably the world’s foremost sky photographer—had a new way, he thought, of measuring a plane’s altitude. He believed that if he could take aloft a camera and shoot pictures of the earth from a sky-sailing plane, he could tell by measuring distances on them how high the plane was. Would Captain Streett take him up to try it? He certainly would. But this was to be no simple trip over’ Wright Field. They would take an XCO-5 plane—the same fragile high-climber that FEeeES

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LAY, 1999 he he n! ‘as . And, reer of m and | for a nearly nes, as tt had ie toa -dge— 1-half- me of slight iber I air, a | hard young at his e dis- story Cap- of the right ‘most y, he tude. loft a earth ll by high reett ould. over’ wy m 3 : that May, 1929 John A. Macready, dean of used for his dashes into the int its nose up, and keep former Lieut. altitude flyers, upper air P° omy plane stopped going up, they would take pictures. The pictures ought ‘ve interesting comparisons with the nm of the altitude-indicating baro- hs that are “corrected” by theoret- 2 pot disputed formulas today to give the world’s official height marks. “ DIDN'T want him to | try it,” Mrs. Streett confessed, when the cap- tain excused himself to find some cigarettes. - Seven miles is too far up in the sky, I think! But I didn’t breathe a word of what I thought to Billy. You know, there’s a sort of unwritten code among flyers wives that they mustn’t admit being worried. Captain Streett returned, took up the eWe struggled into our high-altitude costumes, covered our faces with masks, saw that our oxygen apparatus was in working order, and were under way alittle after eleven in the morning. I never had quite as many clothes on in my life! They were mighty uncomfortable, on the ground, but when we struck the upper air we thanked God for them. “At 15,000 feet above the earth we commenced taking oxygen. There isn't enough air, up there, to breathe. We carried liquid oxygen in bottles and breathed it, after it had vaporized through Dangling from his . Parachute, Lieut. Hutchinson looked up to see the pilotless ©, nOw a mass of flames, heading straight for him! POPULAR SCIENCE MONTHLY a valve, through tubes in our mouths. We had confidence enough in this equipment to dispense with emer- gency cylinders of gas, usually carried on altitude flights. if 4 i * >. » % ar ee a gece — sar: - Be 2s — eee ee 7 + “I grabbed a fire extinguisher and tried to climb out to a place where I could play a stream on the blazing motor. But the wing itself was slippery with oil, and I couldn’t make it.” “Higher and higher we soared, until, an hour and forty minutes after leaving the earth, I couldn’t make the ship go an inch higher. We were at an indicated altitude of 40,200 feet.” “What do you mean by ‘indicated alti- tude?’” Mrs. Streett put in. “What the dashboard instrument shows. It isn’t exactly correct, due to differences in temperature at different levels. Actu- ally our official height turned out to be 37,854 feet-—between seven and eight miles high.” Incidentally this is the unofficial world’s record—there is no official record—for two men in a plane, and a mark within only 564 feet of the free-for-all airplane height mark of the world, set by Lieut. C. C. Champion, U. S. N. “(OLD up there? You don’t know what seventy-six degrees below zero feels like until you’ve been there. But Stevens was merrily taking pictures as fast as he could operate his camera, his fingers warmed by an electrically-heated pair of mittens. At last he tapped me on the shoulder to signal he was through. I started down. “Then a strange thing happened. As we coasted down on an easy glide, I started to slow down the motor so that we could keep on descending—and the motor wouldn't slow! My _ controls seemed to be stuck. By diving I managed to get down a few thousand feet, but the plane, with its propeller whirring away full tilt, wanted to climb right back up again. “I didn’t do any more diving. In a frail ship of this special type, the uprush of air in a forced dive would tear off the wings—and I didn’t want to lose them up there! There I was, trying to shut the motor off, and I couldn’t do it!” Minutes passed—minutes that must have seemed like hours, with the oxygen in the bottles running lower and lower, and no reserve supply aboard. In about twenty minutes, the motor began to cough and splutter. Then it stopped completely. The gas was gone. Down came the plane, gliding like a fragment of paper tossed by the wind. “TI hadn’t the faintest idea where we were,” Streett continued. “We had ‘started over Dayton, but that was a long time ago. My goggles were covered with frost, and my view was limited to what I could see through a hole the size of my thumb-nail cut in each lens. I had no idea what city or town we were over, for when you are that high ordinary land- marks—buildings for instance—are too small to guide you. E tobogganed to earth, the motor catching now and then as a few re- maining drops of fuel trickled into the gas line. When we got down to a warmer level I lifted my goggles and looked around. The first thing I saw was Indianapolis, dead ahead. We had drifted and glided about seventy miles. (Continued on page 156)

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er oo nye ener er arene en ne ane aemenene War Gas Fights Peace-lTime Foes How Uncle Sam’s Chemists Employ Trench Poisons to Rout Bandits, Slay Insect Pests, 3 - oe. = 2 com By ALFRED P. RECK POPULAR SCIENCE MONTHLY Quench Fires Fumigating a U. S. Army bakery with mixture of the fearful hydrocyanic gas, used in French war shells, and tear gas. The latter, by inducing tears, warns of the deadly poison’s presence.. HIGH-POWERED automobile rolled up to a bank in a mid- western city a few months ago. - It was just after the opening hour in the morning. Three flashily dressed young men stepped out while a fourth sat at the steering wheel. The three passed through the revolving doors of the bank. Inside, the cashier was sorting neat piles of green- and gold-backed bills. He looked up as a form darkened the brass- barred windows of his cage. “Yes, sir, what can I do for you?” the cashier asked. The next instant he was looking into the muzzle of an automatic pistol. “Just shove over those bills and be quick about it!” the young man commanded sharply. The cashier's smile disappeared. Underneath the marble ledge of the window, his foot found a button. He pressed hard. There was no sound, no shriek of siren, no clamor of alarm bells. But almost immediately the bank was filled with a dim haze—almost like the smoke of burning tobacco. The bandit coughed. Great tears welled down his face. Then he dropped his pistol and rubbed his eyes with both hands. “T’m blind!” he shrieked to his com- panions; but they were too busy rubbing their own aching eyes to come to his aid. The three attempted to stagger toward the door. They bumped into desks and fixtures and were alternately rubbing their eyes and groping along the floor when the police arrived, threw open the doors, and fastened handcuffs on three May, 1999 Maj. Gen. Amos A. Fries, Chief of the U. §, Army Chemical Warfare Service, which is turning poison gases of war to peace-time uses, thoroughly tamed but cursing bandits, When they were able to see again, a half hour later at police headquarters, their eyes were slightly inflamed but otherwise they were unharmed. “What happened?” they asked. “You guys just bumped into a little tear gas and came crying into our arms like mamma boys,” a hard-boiled sergeant answered. That thwarted bank robbery testifies to the success of the U. S. Army Chemical Warfare Service’s experts in finding peace- time jobs for poison gas. Under Maj. Gen. Amos A. Fries, these wonder workers have found a score of novel ways to put to work the toxic vapors and gas-spraying equip- ment that the war created. ANKS and jewelry stores are secretly installing efficient tear-gas systems,” General Fries told me when I talked with him in his office at Washington, D. C., the other day. “‘It is next to impossible even for a trained eye to detect the openings of tubes that eject the gas, so cleverly do they blend with the fixtures. In a few seconds the potent gas will stop the most carefully planned holdup. The Chemical Warfare Service advises banks and insti- tutions as to the best gas to use and the way to use it.” An entirely different application has been the safeguarding of household gas appliances. Your home, particularly if it is in the West, or located near an oil field, may use natural gas for the kitchen range. In that case, you are safe, for the odor of escaping gas is unmistakable. But the manufactured variety widely used is it self a “poison gas.”” The more deadly it is, the less noticeable its odor. Cases are Experimenting with chemicals to exterminate the boll weevil, destroyer of cotton crops. At left: A tear gas bomb in a policeman’s billy. on record of women who have fallen un- conscious in the (Continued on page 159) May, | now st years exclus across from | menti Will I Senati $150, ( The { towar than | say it Apy ing th opera a new augm single burde worki impro four-h gineer canal carry becon Th: of the projec which again: mena: to bl moun ragua On rocke

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U.S, ich is © uses, andits, gain, a larters, d but 2 little r arms Tgeant ifies to emical peace- . Gen. s have > work equip- cretly ems,” | with ’-, the even igs of May, 1929 POPULAR SCIENCE MONTHLY 25 g i of Nicaragua shows the Tr ented for the canal, all making use of Lake Nicaragua and the San Juan River. Inset shows possible system of locks and power dam at mouth of the lake. +O'Sea Laven By H. C. DAVIS [TACIFIC ITH an engineer for President and a new administration in Washington, a fascinating proj- ect that has long laid dormant now seems Slated for action. For thirteen years the United States has held the exclusive privilege of building a canal across Nicaragua in Central America from the Atlantic to the Pacific, supple- menting the “big ditch” at Panama. Will Uncle Sam go ahead now and do it? At this writing the United States Senate has just voted an appropriation of $150,000 to survey possible canal routes. The first definite step-has been taken toward a new Nicaragua canal bigger than the “ditch” at Panama—and some say it is none too soon. Apparently the Panama Canal is near- ing the limit of its capacity. It is being operated sixteen hours a day and already a new reservoir and dam are planned to augment its water supply. A new set of single locks may eventually share the burden of the double ones now working. Yet even with these improvements and_twenty- four-hour-a-day operation, en- gineers see a time when the canal will be inadequate to carry all the ships desiring passage. Then a new canal will me imperative. That is the setting for one of the most daring engineering projects of all time—one in which man must pit his hand against fever, sharks, and the menace of smoking volcanoes to blast a waterway across mountains and jungles of Nica- ragua from sea to sea. ce one half of Nicaragua rocked in a titanic upheaval of OCEAN igger Ditch Than the Panama LIFT OR STEP OF a Pe. SERIES OF LOCks AY HALF OF THIS ROUTE » 9 ANTIC ND OF USE THE REAL RIVER CANAL VoL. 3,405 FT. DMSO VOL. With an Engineer-President, Uncle Sam Soon May Dig a Billion-Dollar Nicaragua Canal A glimpse of the wild country through which the canal would pass—Lake Nicaragua in the distance. Left: Mt. Momotombo, the volcano which threatens the proposed northern route. earth. Lava from a fuming volcano bottled up a whole arm of the Pacific Ocean. That arm is now Lake Nicaragua, a body of fresh water a third the size of Lake Erie. The whole Nicaragua canal, on paper, centers about this lake. From it the San Juan River winds eastward to the Atlantic Ocean at San Juan del Norte, also known as Greytown, forming a link of water that almost cleaves the isthmus in two. But a (Continued on page 154)

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Photographs of the author by D. Warren Boyer POPULAR SCIENCE MONTHLY I found that you can learn a lot by hanging around the field, watching other pilots take off and land. Am Learning to Be a Flyer The First Forced Landing —Another Big Day in the Life of a Greenhorn Pilot By LARRY BRENT OLONEL CHARLES A. LIND- BERGH gave me a valuable lesson in flying. Not a word passed between us. He did nothing but sit in the cockpit of his plane. Everyone with whom I had talked at Curtiss Field since I enrolled as a student had said, in substance: “If you'll hang around the field and keep your eyes and ears open, you'll learn as much about fly- ing as you will in the air. Watch how the other fellow does it, and learn how the other fellow has used his head in emer- gencies.”” So every day, from early morning until dark, I was spending at the field, observ- ing take-offs and landings, dropping in at this hangar and that, watching riggers and motor men at work on a dozen different makes of planes, listening to “shop talk” in the pilots’ room, and, every afternoon, “ going to school”’ from one to three in one of the hangars, attending lectures given by our instructors and by visiting pilots and aeronautical engineers. In less than a week, I already had one

had learned shorthand in high school, and that I had, in the three years since leaving high school, worked as a newspaper reporter and learned how to grasp what was especially im- portant. into typewritten form at my boarding house near the field every night. And I was studying these notes more diligently than I had studied any subject in high school. I wasn’t flying for fun, but to prepare myself for a commercial flying career. with a lucky girl student—lucky because her wealthy father had just or- dered a Laird-Whirlwind for her as a reward for her first solo—when a small notebook full of data on aviation terms and definitions, principles and theory of flight, rigging, engines, ignition, carbure- tion, instruments, aerology, nav- igation, meteorology, etc. It was fortunate for me that I The notes I was taking I put One morning I was talking May, 199 plane came gliding down to taxied up to the line. Some wa maid < ““There’s Slim now.” — except in the movies, it glimpse of Lindbergh. A small’! gathered at once about his plane Tint bergh had flown north from Washi His goggles were pushed up on his h Minutes passed, and still he sat there ass his motor running. was so excited at seeing hi hardly heard Charles Goan the pod manager, who was standing beside me, He was saying to me: “¢ ‘ET that, Brent. A lot of pilots would run her up to the line, cut the motor, and walk away. Not Shim He'll sit there for fifteen minutes, cooling her down slowly—treating a motor the way she ought to be treated! It’s the wa he does everything. It’s why he got anal with his Atlantic hop. And it’s why he all the time flying all over without havi to sit down. You can’t be finicky enough.” (To “sit down” means to make a forced or emergency landing.) I jotted down all this under the nots. tion, “Be finicky.” It opened a big ney chapter in my studies as an “apprentice flyer.” Later that day I jotted down, great many more notes, because some. body had not been finicky enough. When I had enrolled for my twenty five-hour course, I had asked Gaver about students working to pay for their flying time. He had said that that practice had been discontinued because some of the students did such unsatisfactory work, One of the last of these work-your-way students—he was supposed to be a good mechanic—had adjusted the motor of the plane on which I took a flying lesson that day. ANDY ENSLOW was my instructor, but so far I had seen nothing of him. He was home, ill, with flu. So again! went up with my temporary instructor, Lieut. Assen Jordanoff, a former ace with the German war birds. When we had taxied to the end of the field for our take-off and I had adjusted my goggles and a helmet to which a speaking tube was attached, Jordanof said: “‘This motor sounds rough to me.”

My ears were not yet attuned to the finer ‘shades of motor noises. The roar d

‘*Lindbergh treats the motor right, the way he does every- thing else,’’ said Gaver

May, I! this one The | gathere as 1 ust cates 0 rudder the sti attains insensit I pl the sti either ' ward. still 0! was UP Alm the sti rudder hardly out. | the gr climb. over t tinued altime Jordat “You trols.” Thi prepal seeme under shrink only | ness | that ¢ stay | plane tellige in ex gent powe than It been light] horiz the horiz the n the | pilot. abou top o varie Once ing s horiz I wil my and certe

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es, Cooling , motor the S the Way Zot away ) rh he’s iu Vi | enough! > & forced the nota- L big new pprentice l down a Se some. h. twenty ver about § Ir fly; tice hal e of the Y work, our-way > a good or of the son that itructor, of him. again | tructor, ce with 1 of the djusted hich a rdanof ‘O me.” to the May, 1929 this one sounded to me like all the rest of a voice came mtr the speaking n ‘ou strapped in?” (ae coed oad locked. Inodded. _ “Do not touch the controls, please. The plane commenced to move. As it thered speed I watched, not the ground, — usually did, but the controls, dupli- cates of those in the forward cockpit. The wader pedals were working violently and the stick was wabbling, for, until a ship attains flying speed, the controls are very insensitive. ITH the rudder Jordanoff kept the Woisne headed into the wind. With ‘ck he prevented it from tipping , pl Shddenly the stick went for- ward. This meant that our wheels were still on the ground, but that the tail skid wasup. , Almost imperceptibly, the stick came back. The rudder pedals were moving hardly at all now. I looked out. Our wheels had left the ground. We began to climb. We made a turn over the hangars and con- tinued to climb. When my altimeter read 1,000 feet, Jordanoff’s deep voice said: “You will take the con- trols.” This time I was better prepared. My stomach seemed to be climbing up under my ribs and to be shrinking, but it was the ~ only symptom of nervous- ness I felt. I was learning that a plane really wants to stay up in the air; that a plane is one of the most in- telligent pieces of machinery in existence; more intelli- gent by far than an automobile or a power boat, and infinitely more sensitive than either. I tried to remember all the things I had been told to remember. Hold the stick lightly. Keep the wings level with the horizon and the nose where it belongs on the horizon. Where the horizon should cut across the nose varies according to roar of he motor es every: Gaver, “a the height, seated, of the pilot. In my case, it was about two inches below the top of the radiator. It also varies with different ships. Once I have developed a fly- ing sense, I can ignore the horizon. In fog or at night I will fly level, checking up my sense of balance now and then by glancing at certain instruments. [; WAS rough today. We began hitting bumps. I seemed to be doing nothing right, in spite of the way I had sat, night after night. on the edge of my bed, drill- ing myself in what to do. “Press your stick against that rising wing.” An air current had sent the right wing way up. I gave the stick a sudden POPULAR SCIENCE MONTHLY “Releese all controls,” said Jordanoff. *‘ We will have to land. This motor is bad.” I did so. I looked down. The motor sputtered again. I knew we were about to make a forced landing. Using a card to repre- sent wings, Jordanoff ex- plained the side-slip land- ing, and why it is neces- sary where there’s not enough room to glide in, or if the wind is wrong. push to the right. The wing came down. “You are over-controlling. Hold the stick lightly.” I relaxed my grip. Suddenly the ship dropped. It seemed to drop from under me. We had hit an “air pocket ””—erro- neous term for a down draft of air. It was my first glimpse of Lindbergh. Before he climbed from his plane, he ran the motor for fifteen minutes, cooling her down slowly. “Your nose is too high.” I pushed the stick forward to put the nose lower. “You are steering in a wide circle again. Pick some object on the ground and steer for it.” PICKED a large white house in the center of a dense thicket—probably a millionaire’s mansion. I could see it sliding slowly to the right, preparing to vanish under the plane. Very gingerly— remembering my bad footwork in pre- vious flights—I touched the left rudder. I remembered that one control must not be worked without the other. I gave the stick a little twitch to the left. The house reappeared—straight ahead. “Not bad,” said Jordanoff. My slipping confidence came back. I steered for the white house until it van- ished astern, then I picked a cluster of white buildings farther away. I was not yet steering perfectly straight. The land- mark would—very slowly—slide from side to side. Each time I would make corrections, using rudder and stick. Every few seconds, it seemed to me, Jordanoff would say: “You are not keeping the ship steady. It is wabbling around. Keep it steadier.” When I would make a determined effort to keep the ship steadier, he would say: ‘““Now you are over-controlling. Don’t grasp the stick. Try using just your thumb and one finger.” I wanted to protest that the air was so bumpy today that it was im- possible to keep the ship steady. But the speaking tube worked only one way. I noticed that whenever Jor- danoff had the controls, we flew steadily. There were bumps, but he corrected them so quickly that the ship did not wabble at all. Jordanoff later told me that an experienced pilot is so sensitive to the influences of air currents on his ship that he will often anticipate bumps before he strikes them and will act accordingly.

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a I jotted more items under the note, “Be fin- icky.’’ Somebody hadn’t been finicky enough. I know now that, in those first few lessons, I was nervous and overanxious to keep the ship steady, level, and flying straight. I used will power that morning to relax my hand until I was hardly touching the stick. The ship con- tinued to wabble. First one side would dip down, then the other. Next the nose would go down, and I would pull it back up. This was happening often. SAW by my altimeter that I was slowly losing altitude. Jordanoff had the throttle re- tarded. We were flying at low speed, yet if I were flying the ship prop- erly we would not be losing altitude. Presently I discovered that, while my hand on the stick was relaxed, the rest of me was rigid. I remembered that the school manager had told me always to ride the ship through. That had meant very little before. Now I tried it. I let my body relax—simply sat back and took it easy. The result was magical. The ship im- mediately steadied. All wabbling stopped. Jordanoff said: ““That’s much better.” Flying, I decided, is nine parts state of mind. Since then, at times, I have been almost willing to believe that flying is entirely mental. It certainly takes no strength—a child of five could work the controls. I have heard it expressed an- other way; that a good flyer flies with the seat of his pants. In many cases—mine, for example—the stomach seems to be the seat of the flying instinct. Tense stomach ~—bad flying. Relaxed stomach—good flying. Jordanoff suddenly said: “I will now upset our balance and you will restore it.”’ His hand had been off the stick in the forward cockpit. Now the duplicate in POPULAR SCIENCE MONTHLY my hand began doing things. It went forward and came back and waggled from side to side. The ship began bouncing about. The horizon see- sawed and reeled. -The nose suddenly shot up and the right wings dipped down. Jordanoff: “Put us back where we were.” I tried to remain re- laxed as I took the stick. I tilted it to the left to bring the right wings up, and forward to put the nose down. But the hori- zon was still sliding rap- idly to the left. I gave the right pedal a touch. That corrected the slip. We Jordanoff used a plane which happened to be landing to illustrate to me some of the finer points of piloting. were now flying smoothly and straight. Jordanoff said: “I will take the con- trols again. With a very light touch, follow me. We will try some easy turns. A left turn first. Observe that I will bank first, then put on left rudder. Notice how little rudder is required for making an easy turn.” I obeyed. The stick tilted ever so little to the left. I felt the left pedal move forward perhaps a half inch. The plane was tilting and turning. For every left turn he made, Jordanoff made a right turn. He said: ““(\NE of the worst mistakes some of the old flyers made was in learning to turn only in one direction. They be- came left-handed or right-handed flyers, depending on the direction of turn that came easier for them. Guard against that. Later on you will learn acrobatics and it will be necessary for you to make left or right turns with equal ease. Take the controls. Try a right turn.” I took the stick. I tilted it to the right. | Remembering how I had sent the ship into a bad skid by giving her too much rudder, I touched the right pedal lightly. I looked down the right wings. They May, Igy were banked much more Jordanoff had banked then thy seemed to me we were not turning - — as _ eng bs ordanoff asked: “‘Do yo of wind on your right choker tt : dra I did. He looked back. I nodded, “You are side-slipping. Tog my bank, not enough rudder. More ruddes I pushed the right rudder hard, Th draft tr my we cheek stopped. Ween tinued to turn. I now felt left cheek. — ORDANOFF: “Now you are the other way. Too much ry not enough bank. Straighten out make a left turn. Easier! You must smoothly out of all turns. If you do it smoothly, you will find skidding this way and that.” ; I tried to do it more smoothly, Then were so many things to remembe in a turn: the correct bank, th correct amount of rudder, and th correct position of the nose on the horizon. Too much bank—sid slip. Too much rudder—side slip, Nose too high—stall. Nose ta low—dive. Roll out smoothly. or skid. I began to perspire. I began ty get mad again. Was everybody so dumb their first few lessons Yes—everybody was, but that didn’t make me any happier. For every left turn, I made, right. I made perhaps six of each, Then Jordanoff told me to fy ? straight, to pick some object o the horizon and fly for it. | picked a church steeple. But I could not keep the ship steady now, no matter hoy 1 relaxed. We had been up fifty minutes: I had had enough. Jordanoff took the controls, In my maneuvering we had lost altitude, Without my realizing it, the ground had sneaked up 800 feet—we had dropped from 1,000 to 200. Jordanoff opened the throttle with the intention of climbing when—suddenly— it happened. The motor began to sputter, It sputtered, then, with a snort, it roared again. (Continued on page 140) Jordanoff had told me to hold the stick lig tly, between thumb and forefinger. Every night I practiced this with a piece of broom handle. May; 19

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‘Ss: I had controls, altitude, und had dropped with the denly— sputter, t roared age 140) dle. Preparing to fire a cannon-load of explosive to test its strength against a swinging mortar. By EDWIN KETCHUM ANNONS boom and underground blasts rock the earth at one of the world’s strangest laboratories— the U. S. Bureau of Mines’ ex- perimental station at Bruceton, Pa. Here “explosive engineers” risk death a dozen times a day, handling nitroglycerin and deadlier substances, in an effort to find a blasting agent that miners, farmers, and highway engineers may use in safety. No one blasting powder will fill the pill. Coal miners want an explosive that is proof against a fatal blast when mine gas seeps through the shafts or coal dust powders the rock shelves. Farmers need a different type, that will enlarge a hole for tree planting and leave fissures for the growing tree’s roots; or, if they are stump-pulling, a charge that will blow the stump up out of the ground. En- gineers desire an explosive that will gently push out earth for a tunnel, rather than one that will shatter a mountain. For varied purposes, chemists are con- stantly devising new mixtures of unknown violence. It is to test these new-born titans, as well as to find the best ways of handling old standbys like dynamite and nitroglycerin, that the Bureau of Mines maintains its extraordinary research station. In a turretlike “ballistic pendulum,” a massive affair of steel and cement, is determined the strength of a new ex- plosive. A research engineer weighs out a pound of the powder, places it in a small wheeled cannon on a truck, and tamps the charge with dry clay. Then the cannon is wheeled up face to face with the “pendulum,” an old coast ar- tillery mortar weighing 31,600 pounds. Stirrups suspend the mortar from a steel beam that swings on nickel-steel edges. T A SIGNAL the cannon is fired, £% straight into the mouth of the hang- ing mortar. The cannon leaps backward along the rails. Meanwhile the sixteen- ton pendulum rocks upon its concrete piers, the length of its swing measuring the force of the blast. A different type of pendulum measures the safety of an explosive against pre- ignition by friction or careless handling. POPULAR SCIENCE MONTHLY | Play This machine tells whether an explosive is easily set off A falling pendulum scrapes it repeatedly. by friction. For this test, a technician spreads a quarter-ounce of the explosive upon a cross-grooved plate at the base of the apparatus. Then he steps back to a safe distance and pulls a trip cord. Down swings a pendulum arm, faced with a friction shoe of fiber, from a height of nearly five feet. It scrapes again and again across the explosive powder, pro- pelled by a fifty-pound weight. Some- times the powder explodes; sometimes it doesn’t. If no explosion, burning, or crackling occurs in ten of these trials, the explosive passes the test. Will a powder house containing a new brand of explosive shoot skyward if the concussion of a near-by blast jars it? To find this out, two car- tridges are placed a meas- ured distance apart and one is shot off by electricity. If the other fails to fire, it is moved an inch nearer and the experiment repeated. When it finally goes off, its safe distance from a charge of measured strength is de- termined. A cannon shot of explosive fired into a long steel tube or “gallery” tries out the explosive’s tendency to ignite gas or dust. Shelves in the gallery are sprinkled with coal dust. A novel movie camera BLACK BLASTING POWDER R.P.M. 37.5 Duration of flame 1539 millisec. Height of flame 50.2Iin. — namite! 29 Tag with i YOU had the job of handling fifty- seven varieties of death in a day, could you keep your nerve? Could you avoid the one mistake that might blast you to kingdom come? Here is the thrilling story of experts who risk their lives to make high explosives safer for everyone to use. photographs explosion flames to compare the safety of differ- ent types of explosives. Fast- moving films record the length and duration of the flame, though it is all over so quickly that no eye could follow it. In recent research movies of the spread of a cannon blast through a dust-filled gallery have been made through heavy plate glass windows. They show the traveling explosion"wave and reveal what happens when it hits the dust. Many tests are carried on in an ex- perimental mine in a near-by hill, where to date more than a thousand explosions have been set off. Others are made in “bombproof” dugouts of concrete that look like war-time fortifications. They are a reminder of the hazard that con- stantly menaces the engineers who make explosives safer for others. Electric movie camera that takes pic- tures of an explosion’s spread. Left: i Actual photo of an explosion flame.

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30 Tignes © 2: The Arctic tern, champion long-distance flyer. It flies 22,000 miles a year between its summer home near the North Pole and winter home in the Antarctic; one-way trip takes ten weeks. FEW weeks ago, the House of Representatives at Washington passed a law, previously adopted by the Senate, setting aside at least 125 extensive areas as sanctuaries for the vast flocks of migratory birds that sweep across the North American continent twice a year, and calling for large appropriations to establish and maintain them. The President signed the meas- ure and it became effective. Thus Uncle Sam took the birds under his wing, and the protection of millions of feath- ered creatures which make the United States their home part of the year became definitely a matter of Government con- cern. This measure once more fo- cused public attention on the always baffling mystery of the migratory mass movements of the flying legions which, each spring and autumn, wing their way north and south for thou- sands of miles and find their far-flung breeding and feeding POPULAR SCIENCE MONTHLY ‘Do Birds Fly by Radio Compa t 2 A flock of ducks flying over Maryland on their springtime journey north. The newest theory is that they find their way by the earth’s magnetic lines, much as airplane pilots follow radio beams, May, 19 Bae » ieee ssf Amazing New Facts about the Feathered Pilot Who Chart Their Way Over Thousands of Miles By MICHEL MOK with never failing sense of direction. Why do birds migrate? How do they know when to leave and when to return? What guides the scarlet tanager from Canada to Peru and the nighthawk from the Yukon to the pampas of the Argen- tine? How does the robin find its way back to the identical pear tree it nested in the year before? How can a humming bird, no larger than my thumb, steer a straight course over 500 miles of rolling > Each spring great flocks of birds build nests on Farallon Island, the grounds of previous seasons Government bird refuge in the Pacific, near San Francisco, Calif. the year before? water in a single flight across the Gulf d Mexico? Two hundred years of patient observa tion have given new answers for thes ancient mysteries. Some of the startling new suggestions of science which may at last solve the riddle were told to me the other day by John T. Nichols, of the American Museum of Natural History, New York City. For many years, Mr. Nichols has studied birds and _ ther habits. He is recognized asa leading authority on the sub ject. O* THAT very day news paper dispatches had told of an amazing example of the uncanny ability of birds to chart their courses along the unmarked highways of the sky. A Swedish naturalist, Bengt Berg, trained a flock d wild geese to eat from his hand. The next spring he sa¥ a large “V” of geese high i the air, flying toward him They descended and came t him to be fed. How could these birds, flying probably from the Nile in Africa, retura to the exact spot on the coast of Sweden they had inhabited

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Gulf of oh may > M AY, 1929 ion, Mr. Nichols offered a In exPiathat startled me by its novelty hype oldness. Tiny “radio compasses, and located in the brains of the penePe at catch and record electro- : etic lines of force between the rth and south magnetic poles, he said, = y unerringly pilot the winged wander- pe on their great semiannual flights. 5 d asked him whether he thought — : ible that these “i fling flocks were od. . | guided by Leg = aan ame ts whic e x birds might follow d like mariners tracing f the course of the Gulf Stream. “It is possible, yes,” he told _me; ‘but it is more likely that Nature has en- dowed the birds with some innate electro- magnetic quality that enables them to set their courses by mag- netism, just as avi- ators can follow the line of a radio beam iected from a cer- So point. The hu- man flyer is kept in the lane of the radio beam by the signals a: ee we : ee A squadron of sandpipers skimming close to the water. These birds fly to the Antilles of South America each fall, and return north again in the spring. caught by his receiver. Some kind of ‘“flyways’ runs down natural ‘radio compass’ may do the the Atlantic Coast, same thing for the birds. another along the “However,” he added, “‘this idea really Pacific Coast; others belongs in the field of philosophy, which follow the Mis- deals with theories, and not in that of sissippi Valley and science, which recognizes only facts.” cross the Gulf of Mexico. F THE “radio compass” theory should However, one puz- . prove to be correct, it would revolu-§ zle is not cleared up tionize the entire study of bird migration. by the “radio com- It would explain why birds can maintain pass” theory. That their aerial courses through thick and _ is the mystery of the foggy weather, how the golden plover homing pigeon’s abil- guides its flight from Nova Scotia to ity to find its loft, Venezuela, 2,400 miles over water and even if freed as far out of sight of land, and why storms fail as 1,500 miles from to divert birds of passage from their home, and _ regardless routes. It also would explain how they of the compass direc- keep to established “‘fiyways.” Orni- tion of its flight. POPULAR SCIENCE MONTHLY Migrating geese in V-shaped flying formation. Left: A flock of birds landing on the Atlantic coast along one of the much-traveled migration ‘“‘flyways.’’ instinct or sixth sense as the secret of the directive powers of birds of passage,” Mr. Nichols said. ‘“‘But this is accepted by few scientists to- day. The majority incline to the belief that habit, location, memory, and association guide them on their long trips. ““A few years ago, the theory that the warmth of air currents plays an important part in steering them over land and sea was popular. You see, warm rising columns of air are found over about half the earth’s surface. They are closely connected and, as a rule, move in an orderly manner. According to this notion, the birds, keenly sensitive to changes in tempera- ture, could find these columns and, once in them, could easily sail with or against them at will. But this theory is pretty well exploded now, along with many others. I favor the idea that the seasons hold the key to the old direction mys- tery.” “TP\HE seasons?” “*Look,” he explained. “‘On their southward trip in the autumn, the golden plovers, for instance, use flyways that are almost wholly over water on their journey to South America. And in the spring, they return north over land by way of Central America. This is clearly because the seasons lag over the sea. In the fall, temperatures drop more rapidly on the continent than they do over the ocean. In the spring, the air over the land warms more readily than the atmosphere over the water. That, I think, is the reason why many migratory birds go south by water routes and come back by way of the Isthmus of Panama and Mexico.” Observations by or- nithologists the world over bear out this view. It is a well-established fact that the movements of the average minimum temperature, which nat- uralists call the “frost line,” are the signals for the migrant’s semiannual departure’ and return. As soon as their sum- mer breeding and molt- thologists have long known that migrat- “Some investiga- Bank swallows off for their journey ing activities are over i birds h Sella the tess hay . sted to the coast of South America. Their d the d begin t ng each year follow the same tors have suggeste aie, ae dia a Ge e days begin to highways of the sky. One of these a special flying to the Gulf of Mexico and vanishes! (Continued on page 149)

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ee The Man POPULAR SCIENCE MONTHLY Who Made Radio T And Gave the Movies a Voice—The Dramatic Story of Lee De Forest, Inventor of the Audion Tube By FRANK PARKER STOCKBRIDGE N EAGER-MINDED boy, com- pelled by circumstances to sup- press: most of a boy’s natural outlets for his energy. A keen-minded, __ diffident youth, with nothing in common with his schoolmates, thrown back upon his own — in his effort to fit himself for ife. A shy, introspective college student, unable to express himself among his fel- lows in any manner but through his work in classroom and laboratory. A visionary young man, fired Court's decision pours millions in deferred royalties into his pocket—millions for which he has no personal love nor need— he is all through with radio. All of Lee De Forest’s interests today are in the movies. For, just as he taught the radio how to talk, he has given the motion picture a voice. The De Forest phonofilm is the parent of the “talkies,” as his audion tube is of broadcasting. Others have discovered the ways of accomplishing the same or similar results, but it was Lee De Forest’s nique in the field of his labors, gays unfilled need and set about to find @) to fill it. As a post-graduate students the Sheffield Scientific School af * the youthful De Forest, having recognims the need of a better way of detect less waves than Marconi had found. voted the next half-dozen years | pursuit of that way, until he found i, That was his sole recreation as @ and a young man—the pursuit of kung edge. Born on August 26, 1873, in Gom, cil Bluffs, Iowa, where his father way. Congregational minister, he ¥ with inspiration through read- ing of Tesla’s and Marconi’s experiments with the Hertzian waves, seeking—and finding— a better way to.make the wire- less telegraph work. An “impractical” inventor, easily preyed upon by unscrupu- lous promoters, betrayed. by friends, sneered at by rival in- ventors, his patents infringed by others, disheartened, baffled, al- most beaten by the world which he had never learned how to fight. Then, suddenly, the wheel turns and Lee De Forest is sit- ting on top of the world. He made the wireless speak! Modern radio, as we know it, springs from De Forest’s audion tube. It made voice transmis- sion and_ therefore modern broadcasting possible and prac- tical. Applied to the wires, it is the foundation of all long-dis- tance telephony. It -has turned inventors, he ite, HE story of Lee De Forest, and of his long and bitter court struggle for possession of the basic patents on the audion tube, runs parallel to the history of radio. Like most great has been maligned, ridiculed, baffled—and all but beaten. Today he emerges victorious, vindi- cated in his claim to be called the father of radio broadcasting. Here Mr. Stockbridge writes the drama of the timid, unsociable youth who set his face toward a goal and learned how to fight to win it.—The Editor. taken as a boy of six to Ty ladega, Alabama, where father became the head of om of the earliest colleges ig negroes. “TT WAS a difficult envirgp. ment for a boy,”’ De Fon told me. “I could not ss with the negro children on of equality, and the children ¢ the white families in the tom were not permitted to associat with me, because my father was committing the then unpardop- able crime, in Southern eyes, educating negroes. My brothe. and sister and myself, and th few other children of white teachers of the college, had to build up a little social system ol our own, which was too narrow and limited to be good for us Out of such an environment 4 boy grows up either arrogant or diffident. He has had no oppor tunity to associate with his the world of communications equals, and feels himself either upside down. Two weeks ago, as this is written, the Supreme Court of the United States officially proclaimed Lee De Forest the “daddy” of modern radio. The highest tribunal in the land at last upheld his basic patents on the audion tube in its applications as a radio detector, a radio amplifier, an oscillator, and a regenerator in receiving sets. THE spare, kindly, gentle-voiced, gray-haired man with whom I talked in his laboratory in New York, this be- lated confirmation of his pioneer claims came as no surprise. There is a simple faith about Lee De Forest’s outlook on life, a faith based upon the belief that somehow, sometime, every man gets what he deserves. He knew he was right, and was not in the least elated when the nine great jurists on the bench in Washington agreed with him. In his matured philoso- phy of life, the world’s acclaim means nothing to him. Except as the Supreme original conception’of photographing sound on the same film which carries the picture which has revolutionized the art of the cinema. I submit that Edison himself, at fifty- five—De Forest’s present age—had hardly achieved anything more far-reach- ing than these two accomplishments, of making the radio and the movies talk. I found it almost as hard to get De Forest to talk as he had found it to coax them into speech. Sitting at his desk in the big building which was designed as a studio for Norma Talmadge’s motion pic- ture productions, he overcame his dif- fidence sufficiently, however, to give me the high-lights of an inventor’s methods and to indulge in a bit of forecasting of the future possibilities in his fields of work. The invention of the audion tube was no accident. Like most great inventions, it came about because a man of vision and imagination, familiar with the tech- superior or inferior to all with whom he comes in contact. “T came through that experience shy, diffident, without knowledge of the world or of life. I had plenty of book know edge, but none of practical affairs. My father, by the utmost frugality, managed to find enough money to send me toa preparatory school in the North, a obscure, sectarian school at Mount He mon, Mass., where my schoolmates wert farm boys, unfamiliar with the cultum standards of my parents’ home but far beyond me in their ability to adjust them selves to the give-and-take of community life. The result was to drive me farther into myself, so that when I finally entered Yale I was probably the most timid, ut social student who ever went to New Haven.” * The course at Yale was achieved only at the cost of a tremendous struggle against this handicap and financial diff culties. Only the inborn American pa sion for education (Continued on page 132)

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system of 0 narrow d for us. ynment a rogant or 10 Oppor- with his elf either all with nce shy, he world : knowl rs. My managed me toa rth, an int He- tes were cultural but far st them- amunity _ farther entered nid, um to New ed only struggle al diffi- an pas age 132) POPULAR SCIENCE MONTHLY Drawn from life especially for PopuLarR ScteNcE MonrTHLz by B. J. Rosenmeyer Lee De Forest, Father of Broadcasting Sole inventor of the three-element vacuum tube, by recent judgment of the highest court in the land, Dr. De Forest stands as the radio pioneer who made practicable wireless communication beyond the limited field of code telegraphy and 80 gave the world broadcasting of speech, music, and entertainment. He also was the first to record sound on a motion picture film. ——- et ne a= >

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- “9° » 2. -. ae The Fence Held A few thin bands of iron were all that saved this delivery car from a twenty-foot plunge over the brink, when it skidded and waltzed across icy pavement of a viaduct at Jersey City, N. J. The rear wheels tore a section of the iron fence from its foundation and went clear off the edge. There the car teetered precariously above the street— but the fence held, Right Through the Wall After crashing through a thick stone wall, this big coal truck came to a stop with its nose out over the edge of a New York City viaduct. Only the fact that ite rear wheels were held fast in the shattered masonry prevented disaster. POPULAR SCIENCE MONTHLY Hanging by an Eyelash! Three Inches to Go! Just three inches more, and this fire truck would have dived over a fifty-foot bluff in New York City. A skid did it. The machine below just missed jumping off a bridge at Germantown, Pa. Was He Scared? The driver of the truck pictur above owes his life to a two-toa | joad of sand it was carrying, Turning sharply to avoid hitting an automobile on a drawbridge” across the Harlem River, New” York City, the machine struck @ pillar, plunged through a “i rail, and hung over empty aif, anchored only by the weight of © the sand. The picture in the circle” shows a similar breath-taking ex perience of another truck after a collision with an automobile on Manchester Bridge, Pittsburgh, Pa, It Might Have Been Worse Another close call, at the approach to a Ha River bridge. To avoid possibility of such dents, many of the highways now are by heavy steel cables or netting wherever higt embankments or sharp turns offer greatest dange:

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POPULAR SCIENCE MONTHLY A shopping district is housed in the Ponte Vecchio, over the Arno River at Florence Italy. The roofed bridge is lined with stores trange ridges Building this viaduct across ee. |° i Natives of Yunnan prov- the gorge of a small stream | La S ince, China, built this near Nice, France, engi- “ : Y wl. sturdy suspension bridge 4 oe of tough wistaria vines, / proving the plant useful for more than its flowers. devised an unusual ma- sonry arch support set at fight angles to the span. On the grounds of’ the Summer Palace of former Chinese rulers at Peking stands thie ornate bridge, humped like a camel, The covered bridge, like the covered wagon, has all but vanished in You couldn’t jump from this bridge if you tried. Savages in jungle America. Here is one of the last of the line, battered by the ravages country of India built it across a swift-moving mountain stream, of time but still creaking under traffic three miles from Covington, Va. using homemade ropes for the main cables, interwoven with withes.

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POPULAR SCIENCE MONTHLY Mail Down on the farm at Trichinopoly, southern India, they have no running ‘ : water, garden hose, nor sprinkler, § | they hitch the cow to a crude derrick that lifts water in a bucket from a pool ~ to the level of the field for irrigation, It’s a far cry from the electric pumping machines on modern farms to this primitive pump worked by a revolving camel at a desert water ‘hole in Egypt. Note the crude gearing. Projecting wooden- pins in one wheel engage rods in the other. atering the World’s SOW the world has ad- vanced in machinery for drawing water for farms and gardens is told here in pictures from many lands. To irrigate their paddy fields, Chinese families Right: A Siamese in the Soochow region woman gets her daily work the treadmill for exercise by working hours, as shown at left. a treadmill irriga- tion pump in the rice fields. Compare this primitive machinery with huge modern irrigation dam below A primitive “super-power” irrigation plant at Ouang Ngai, in Annan. province of French Indo-China. A battery of huge bamboo water wheels, revolving side by side in the same stream, supply irrigation for a large farm near by. The running stream passes through a series of sluices to drive the light wheels, whose power pumps the water to a higher level. An ingenious machine, but a far cry from the modern way, at right. The modern way—the great Roosevelt irrigation dam in the Salt River Valley, Arizona. Its waters have reclaimed more than 200,000 acres of arid land, once the abode of rattlesnakes, and have built a rich agricul- tural region, with half a dozen thriving towns. The dam is 284 feet high and 1,080 feet long. Its storage capacity is 533,000 million gallons. It was built by the U. S. Government in 1911, at a cost of $3,890,000.

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May, 19% May, 1929 Tunning ler, §o derrick 7 ma pool — tigation, It River acres of agricul- ret high gallons. 390,000. Part of the job of surveying to make accurate maps of a coast line is the and steady nerves of a steeplejack— particularly in the gale-swept regions of the Caribbean. An operator at the sonic depth finder, the new instrument for measuring ocean depths. Sound signals are sent from the bottom of the vessel, and the time required for their echoes to return from the ocean floor and be heard on this receiver tells the depth accurately, Surveying under difficulties—waist- deep in tropical waters. While one engineer sights his instrument, the other holds up a big umbrella as a shield from the blazing sun, all the time keeping a sharp watch for alligators. Little known shores, once the lair of notorious pirates, thus are being accurately mapped. POPULAR SCIENCE MONTHLY Making New Maps of the Sea ADING waist-deep in alligator- infested waters, battling the raging surf in small boats, pierc- ing the jungles, or climbing mountains with heavy instruments—it’s all in the day’s work for the U. S. Naval Hydro- graphic engineers who, with the steamers Hannibal, Niagara, and Nokomis, are charting anew the shores of Central America and the West Indies, mapping dangerous reefs and shoals of the Carib- bean Sea. On this page are glimpses of the adventurous tasks by which surveyors of the deep are mak- ing navigation safer. Wind, waves, and spray beat against the engineers in this small craft, crossing a bar on the way out to sea after surveying inshore. To get accurate figures on shore lines and depths, the surveyors often must land their small boats, with their tripods and instru- ments, on the wave-swept beach. a Lowering a marker for the marine surveyors over the side of one of the Government vessels. This float, with signal mast, is designed to remain upright on the waves. The old way of measuring the depth of the sea —with a sounding lead at the end of thousands of feet of piano wire. Though still widely used, this apparatus is being replaced by the new sonic depth finder, pictured across the page. Mountain climbers, too. Not even a treacherous crevasse of a volcano can stop the surveyors from getting their figures. No Alpine safety ropes to catch this man, either, if he misjudges his distance in leaping the chasm. It’s no job for tenderfeet.

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ONES of dino saurs and prehistoric monsters, found in all parts of the world, are continually added to the famous collection in the American Museum of Natural History. There they are filed in storage racks, later to be ag- sembled into the skeleton , of some strange creature that lived thousands of years ago. Below: Dust- ing skull of an extinct rhinoceros from Kansas, using a vacuum cleaner. POPULAR SCIENCE MONTHLY Before the Roc Moun tains existed ~ whey Colorado was as fist ® Kansas, the terrible Bron, tosauri, or thunder lizards, States. Judging from their | bones, this is how looked, some two o.. years ago. The est were twenty-five fer long and twelve feet high Bringing Dinosaurs Measuring one of the largest dino bones in the world, at the Ame: Museum. It is the huge femur, @ thigh bone, seventy-one inches long= taller than man standing beside . “es € . te, 2 — +0 : a fe ‘ : i * | sey a & tad . if i . Two of the Museum’s experts in the restoration of the bones of past ages—Otto Falkenbach (left) and George Olson—are seen here at their work, dolling up the queer skulls of fossil animals for exhibition. A battle of monsters 3,000,000 years ago, From rocky imprints of dinosaur feet, and ; : from bones, experts 1 d ’ ee ei reconstructed pose , F oe al —— showing the start of . ‘et j ye the titanic struggle. ; j si Fe: oS ae S The filing case of pre , . historic bones. On the table is the skeleton of Scientists themselves gasp in amazement as dinosaurs ‘“‘come to Here is the skeleton of the thunder lizard, pic- tured at top of page. the armor-plated dino saur that once roamed in Colorado and Wy- oming. Dr. G. G Simpson, associate curator of vertebrate paleontology, hclds the tail of the monster

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8 gpitgen’ pf > 4 ~4 z rg POPULAR SCIENCE MONTHLY uman Moles iver Lubes he ) fa rife Close Quarters ar 2 Sand hogs bolting one of A High Pressure Job ; ‘ .) the hae conten —~ Two hours is a good day’s work for the “sand a. - — ptr ag a hogs” who, under air pressure three to four ing chamber that ter: med times as great as that of the outside atmos- ‘ often half phere, are digging two new rapid transit tubes ; ” labor naked. under the East River, New York City. Here is a gang in the air lock, reading while pres- sure is raised to that of the working chamber. On the Front Line At the nose of the tunnel a huge cutting shield is driven ahead by powerful jacks. These men are seen digging out the loosened material where the shield has penetrated. The Finished Shell A section of the completed shell of the tunnel, showing how the rings are fitted together. In the distance is the entrance to the working chamber. No Weaklings Need Apply A physician tests the heart of a prospective sand hog after a trial in the pressure chamber. Behind them is the entrance to the air lock, where gradually in- creasing pressure prevents caisson disease, or ‘“‘bends.”” Bringing Up the Diggings New York entrance to the tunnels. Dump cars loaded with material are hauled to the surface by electric engines through special air locks.

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40 POPULAR SCIENCE MONTHLY May, 199 Setting the Pace in Aviation A Flying Radio Laboratory The Biggest of Them All? In the cabin of a large monoplane, Harry Diamond A plane of ordinary size nestles easily under oy (left), expert of the Bureau of Standards, runs a wing tip of this mammoth Junkers monoplay laboratory where he tests radios used by pilots for recently completed in Germany. It is driven by receiving radio beacon signals and weather reports. four motors, and has two pairs of landing wheeh Called **Fool-Proof’’ At the left is the latest attempt to make a “fool-proof’’ plane. The designer, Fred L. Bronson, of Los Angeles, says auto drivers can fly it. Its wing angle is said to give unusual stability and a landing speed of twenty miles an hour, For Wind Tunnel Tests An electrically heated wire, one fifth as thick as a human hair, is used in this Bureau of Stand- ards instrument to measure wind velocities. Model Propeller Pulls 15 Pounds A model of a new twin propeller for airplanes demonstrates its efficiency by pulling a toy cart with a fifteen-pound load across the floor. The two propellers, side by side, whirl in opposite directions. This has balancing effect of a gyro- scope, the inventor says, eliminating torque vt twisting force and increasing pulling power. All Aboard! At the right is one of America’s newest air liners, the luxurious twenty-passen- ger monoplane Patrician, at Curtiss Field, N. ¥. It is driven 130 miles an hour by three 525-horsepower motors.

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ily under Oty rs m t is driven by nding wheel oO make signer, » hour, thick as F Stand- locities, May. 1929 POPULAR SCIENCE MONTHLY 4l Building the First Winged Dirigible—A utogiros for America—New Devices for Speed and Safety INGED dirigibles, men- tioned not long ago by Henry Ford as a worth while possi- bility in aviation, seem about to ———, a oy English firm has just pl orders in aon, reports say, for a curious hy- brid machine that will be half airplane and half dirigible. It is to have a gas bag of 420,000 cubic feet capacity, making: it a full-fledged airship; but a set of wings like those of a plane will extend from the body to help support it in flight and also to facilitate landing, thus elimi- nating a large ground crew. | Intended for passenger service, the odd 130-foot craft is to carry six ngers, a two-man crew, and mail and baggage. It will be semirigid with a frame of steel tubing. Two motors of only thirty-five horsepower each are expected to give it a cruising speed of sixty miles an hour. Rubber Airplanes Now! HE newest structural material for aviation construction is a novel “lumber” made by pressing together two sheets of hard rub- ber, with an inner layer of sponge rubber between. Already the sub- stance has been used to build motor boats, and now it has en- tered the airplane field as well. New Safety Slots Y THE addition of an auto- matic locking device, the newest Navy two-seater plane, a speedy Vought Corsair, im- proves the safety ““wing slots” recently developed in England. It is said to be the first plane in America to be equipped with them. A test pilot at Long Island, N. Y., deliberately put the new plane into a spin, then pressed a release lever that un- locked the slots—a pair of small auxiliary wings mounted above the main ones. The added control surfaces brought the plane out of the spin in half a turn. The lock is an answer to pilots who have ob- (— slots enable a pilot in doubt to flatten out for a landing ten feet above the water and “pancake” or drop flat into it without damage. An Air Beacon of Steam GIGANTIC jet of escaping steam serves as an unusual type of air bea- con at a Harrison, N. J., lamp factory. Engineers discovered that when the jet was bathed in the brilliant light of 25,000,000-candlepower floodlights, some N AIR mail plane was streaking across the Carson Sink Desert in Nevada re- cently when one of its passengers snapped this remarkable photograph of the plane’s moving shadow on the sands. It tells better than words the new romance of the fast mail, winging its way over vast expanses of our continent. If all the 160,000,000 letters sent by air mail during the last three years were strung end to end, they would form a trail leading nearly around the world. And a postmaster, canceling a letter every second, would have to work day and night for five years to complete stamping the batch! cairn, president of an eastern aviation firm. They head a list of more than a dozen European types of planes and en- gines to be made here during 1929 by a number of American firms; - indicating that American aviation is shortly to feel a distinct foreign influence. Savoia-Marchetti seaplanes, used by Francesco di Pinedo in his 1927 tri- continent trans-Atlantic flight, and by Ferrarin and Del Prete last year when those Italian airmen hung up a long- distance flying record that still stands, will be built at Port Washington, N. Y. A $1,000,000 seaplane base is to be included in the project. Caproni airplanes, among the largest in the world, are to be built by another American firm according to the design of Gianni Caproni, whose bombers were used by the Allies in the war. The DeHavilland Moth and the Avro Avian, popular small sport planes in England, now are to be made here as well. American machinery also may turn out the giant Dornier and Rohrbach flying boats designed by German firms. Meanwhile, what is termed the largest aeronautical enterprise in America has been launched with the formation of a $200,000,000 aviation corporation. A score of powerful banks and presidents of railroad and steamship firms are hacking the new company. Huge New York Airport WELVE minutes from New York City by automobile, and only five minutes away by pneumatic mail tube, an im- mense airport, to be built in the waste land of the Hackensack, N. J., meadows, is announced by a new $10,000,000 firm. A thousand acres of land have been secured at this writing, and work on the airport is to begin immediately. By early fall, it is expected, the first runways will be ready for use. An artificial lake of fifty-six acres, for seaplane landings, is a novel feature of the project. jected to the previous auto- Radio Lights matic type of antispin slots, contending that though in emergency they provide additional control surface, they interfere with aerial acrobatics. An unforeseen use of the slots is to facilitate landings upon water by enabling es to slow up without loss of control. Capt. W. R. Maxwell, director of pro- vincial aviation for Ontario, Canada, finds that DeHavilland Moth seaplanes equipped with the slots are preferred by Forest Service pilots. It is hard to judge height above water, they say; and the green, others blue, red, and amber, the beacon could be seen at night ten miles away. By day the unique beacon is a wind indicator for airmen. Autogiros for America INGLESS “autogiros” or Cierva windmill planes, which can land in almost any back yard, are to be manu- factured in America, according to a recent announcement of Harold F. Pit- the Airport HILE an approaching plane equip- ped with a siren lit its own airport lights at Newark Airport, N. J., the other day, as is told elsewhere in this issue, another system of remote control was being demonstrated at a Birmingham, Ala., field. It consists of a radio trans- mitter mounted on a plane. The approaching pilot operates his radio and an automatic receiver located on the field responds by turning on the lights.

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42 X-Rays Trap Art Counterfeiter Restoration of an old portrait by Badile, tested by X-rays in Harvard’s Fogg Museum. FURORE was created in Ameri- can and European art circles a few weeks ago by a unique law- suit brought in the courts of New York by Mrs. Andrée Hahn, of Kansas City, Mo., against Sir Joseph Duveen, internationally known art dealer and connoisseur. Mrs. Hahn demanded $500,000 in damages because Sir Joseph had branded as a fake her highly prized “old master,” a portrait of a young woman entitled “La Belle Ferroniére,”’ and attributed to Leonardo da Vinci, the great fifteenth century Florentine artist. Sir Joseph asserted the painting was a copy, and a poor one, of a similar picture in the Louvre, the French National Museum in Paris. Not only artists and art experts, but the world of science, as well, closely followed the trial. For science was called upon to play the dramatic rdéle POPULAR SCIENCE MONTHLY How the New Sleuths of Science Run Down Frauds and Identify the Old Masters by Their “Fingerprints” By JOHN E. LODGE the picture with almost infallible accuracy. Then, by means of microscopic photo- graphs, the artist’s brush stroke. which in many cases is as individual as hand- writing, can be recognized. Finally, the X-ray tube is brought into play to reveal the picture’s telltale “under layers,” which frequently leave little doubt of its authorship. The first chemist to study and dis- tinguish the paints used in different periods was Prof. A. O. Laurie, of Edin- burgh, Scotland. He found, for example, that smalt blue was first used by artists at the close of the sixteenth century and that azurite became popular about 1480, to disappear again from the masters’ palettes around the year 1650. Not long ago, he was asked to pass upon the authenticity of the Rokeby Venus by Velasquez, the great Spanish portrait painter of the first half of the seventeenth century. Professor Laurie entirely disregarded the matter of style and technique. Instead, he examined a microscopic fragment of the paint in a blue ribbon on a cupid appearing in the composition, and discovered that it was May, 19% X-ray photograph of same portrait, revegl. ing original condition before it was Testored, a mixture of smalt blue and azurite. this way, he refuted the contentions ¢ a number of art experts who had declara the cupid to be an eighteenth century addition to the painting. Incidentally, in the “Belle Ferroniére’ controversy, ‘Professor Laurie is ranged on the side of the experts who hold that the painting in the Louvre is the genuin one. He recently subjected some of its paints to microscopic examination and found that they were the pigments fo which Da Vinci, in his writings, expressel a preference in depicting flesh. FEW months ago, six tiny samples not bigger than a pinhead each, were taken from a painting in Californis and shipped to Professor Laurie in Edin- burgh by the owner, who had some mis givings about its authenticity. Although he had never seen the of detective in tracing -— the possible fingerprints of the counterfeiter of “old masters.”” Among the foremost witnesses were noted chemists and X-ray specialists. And though in the end the jury failed to agree and was dismissed, vivid light was shed on the wonder- ful methods now used by scientific investigators to determine whether a work of art is authentic. Broadly speaking, there are three such sci- entific methods. By us- ing a filed-off hypodermic needle to remove a tiny piece of paint, not larger then a pin point, from a disputed canvas and 4 placing this particle of pigment under the mic- roscope, color chemists can determine the age of & painting, the chemist was able to reassure the collector! The other day, Laurie’s methods wer successfully applied in New York to unmask a canvas that had been offered to a_ wealthy business man as. the work of Jacob van Ruys dael, most celebrated of the seventeenth century Dutch landscape paint- ers. A chemist simply “lifted” three bits of paint and a tiny sliver of the oak panel om which the landscape was painted. The brief re port submitted by the investigator is a m detective story in min ature: “This painting is an Where science trails the art fakers. Testing a painting in the Fogg Museum. Alan Burroughs, expert in the use of X-rays to detect frauds, stands second from the right. imitation, but is pi ably between fifty

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ait, reveal. 3 restored, zurite, Jy entions of d declare h century erroniére” is hold fa le genuine me of its ition and nents for expressed Samples, ad each, alifornis in Edin. ome mis- Although seen the chemist ssure the r day, is were plied in nmask a May, 1929 venty-five years old for the following se a white pigment used in the sky -. of zinc oxide, which was unknown a hundred years ago. The Flemish vainters used flake white and not zinc white. 7 , “ *+»men used in the shadows is an eat. Bitumen three hundred old is converted by light into paar and becomes insoluble. 4 microscopic examination of POPULAR SCIENCE MONTHLY for a color chemist to determine that a picture in which any of these modern pigments are used could not possibly be an example of the Florentine school. The photomicrographic method of detecting frauds also was developed by Professor Laurie, who makes _photo- graphic enlargements of two to five diameters. Some years ago, the authen- ticity of Rembrandt’s famous “Good Samaritan” was questioned. Professor 43 Some years ago, Dr. Alexander Faber, of Weimar, Germany, discovered that X-rays could be employed to determine whether an old master was an original, a restoration, or a falsification. He found that X-rays penetrate some pigments more easily than others. A heavy pig- ment appears beneath a light one, just as, in the case of medical application of X-ray photography, a bone appears dis- tinctly beneath a covering of flesh. Dr. Faber’s work was de-

on which the picture is i hows that the proto- ror the cells has not entirely dried out. Wood three hundred years old shows no such proto- plasm.” DLESS to say, the fraud- lent “Ruysdael” was not Magaking of zinc white, Profes- sor Laurie definitely established that it was not used by painters until 1781. The artists of the Florentine school, of which Da Vinci is the foremost exponent, had comparatively few colors to work with. For whites they used either chalk-gypsum or white lead. Their yellows consisted of orpiment, a yellow sulphide of arsenic which blackens in time; Naples yellow, of which lead and antimony oxides are the com- ponent parts; and yellow ochre, a clay stained with iron oxides. Their greens were verdigris, a copper acetate; malachite, a cop- per-bearing ore; and terre-verte, which is a green ochre. The crushed and powdered semi- precious stone, lapis lazuli, fur- nished them with a blue not un- like the ultramarine of the present

veloped in Europe by Dr. André Cheron, of Paris, and Dr. Heil- bron, of Amsterdam, and in this country by Alan Burroughs, who, for the last eighteen months, has been making extensive X-ray experiments in the Fogg Art Museum, at Cambridge, Mass. This museum now has a file of about 1,000 X-ray photographs of masterpieces, representing the peculiar characteristics of many masters, ancient and modern. Through application of the X-ray method, Burroughs not long ago established the authen- ticity of a portrait by Frans Pour- bus, noted sixteenth century Flemish artist. The picture was supposed to be a likeness of Queen Elizabeth, but the features were so insipid and ultra-feminine that some American critics doubted the identity of both the artist and the sitter. Other experts, how- ever, believed that the painting bore the unmistakable marks of Pourbus’ technique. URROUGHS, with his X-ray apparatus, found an “under layer,”’ revealing the same general characteristics of the painter’s handiwork but showing a lady of

day. Their reds were vermilion, a sulphide of mercury; red ochres; red lead compounds; madder lakes, produced from the root of the madder, a flowering herb; and possibly also a red lake derived from a red gum. On the other hand, our brilliant yel- lows, such as cadmium and chrome, were not known. It was not until centuries later that cobalt and cerulean blue were first introduced, and Prussian blue was not discovered until 1720. Carmine, which is obtained from a little Mexican insect called the cochineal, was un- known. Thus it is comparatively easy S. Kennedy North, British artist and critic, with X-ray apparatus for testing paintings and exposing forgeries. Laurie confounded the cynics by making enlargements of the brushwork in this picture, which is one of the star exhibits in the Wallace collection in London, and likewise of Rembrandt’s “Woman Taken in Adultery” in the National Gallery, and pasting parts of the print of one over that of the other. The experts were entirely unable to tell the difference! The X-ray system of picture examina- tion now is used in virtually all of the large art galleries in Europe and America. much stronger features. In fact, the “invisible” picture under- neath the visible one conformed to the generally accepted idea of Queen Bess’ somewhat mannish appearance. The inference finally drawn was that Pourbus had been prevailed. upon to “doll up” his original portrait. An idea of the importance of modern scientific detection was given not long ago by Dr. Wilhelm Bode, of the Kaiser Wilhelm Museum in Berlin. “Rembrandt,” he said, “painted about 700 pictures. Of these, more than 3,000 >? are in existence!

r, Cit away wood panel to Gce of paintine. ¢ } < t 1s FJlace coating ot gelatine or wet sheets of tissue paper.or paste sheet of muslin on surface ot painting

7

' - = ° Iemove wood from back of painting by planing and sandpapering to original preparation under painting

rv, Wiount new canvas to surtace where wood was removed. atterward removing gelatine or muslin, etc

How restorers create “canvases’’ out of old paintings which were originally done on bases of plaster or similar material mounted on wood. After the painting has been cut from the panel, its face is covered, Then the wooden back is carefully planed away and a canvas mounted in its place.

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KARL VOOGHT N SOUTHERN Califor- nia, the highest dam in the world has just been completed. It stands in the Pacoima Canyon, an arched wall of reinforced con- crete nearly two and a half times as high as Niagara Falls! This cement barrier, 385 feet from base to top, will guard the fertile San Fernando Val- ley from floods. The new dam’s hold upon the record for height will be short lived, ‘for the Owyhee River Dam, in Oregon, already under construction, is to be 405 feet high, or twenty feet taller than the Pacoima structure. The possible height of rein- forced concrete dams seems to be limited only by the solidity of their rock foundation. Ever since man began to settle down and build solid dwellings, some sort of cement has been used. Mud probably was the first cement. The Great Pyramids of Egypt were held together by a mortar of burned gypsum. Volcanic ashes and burned lime made the strong masonry of Rome possible. Since 1870, the United States has been using Portland cement, but only since 1910 has reinforced concrete come into wide use. Today, it is surpassed only by steel as a building material and its possi- bilities in bridge and dam construction are just beginning to be realized. Your Newspaper by Radio NEW YORK corporation has ap- plied to the Federal Radio Commis- sion for permission to establish radio newspapers in the cities of New York, Washington, Boston, Chicago, Cleveland, Columbus, Cincinnati, Detroit, Kansas City, St. Louis, New Orleans, Atlanta, Salt Lake City, San Francisco, Los An- geles, Seattle, Minneapolis, Dallas, and Philadelphia. The company has for its purpose distribution of news only. It is a far cry from this proposal to the town criers who provided Americans of the Revolutionary period with their daily news. The nineteenth century was well under way before daily newspapers began to attract large circles of readers. And the first quarter of the twentieth cen- tury has brought daily newspapers to their highest development, the total net circulation of American newspapers now being more than 37,000,000 daily. Thoughtful newspaper men, watching America’s radio audience grow to more than 40,000,000, for some time have been summing up the possibilities of radio sup- planting big dailies as a distributor of news. Broadcasting stations all over the land have been sending out news bulletins POPULAR SCIENCE MONTHLY A giant concrete barrier— Pacoima Canyon Dam, highest in the world. It will guard San Fernando Valley, Calif., from floods. Right: Looking up the face of the lofty wall, which is nearly two and a half times as high as Niagara Falls. and Americans in gen- eral are beginning to get their first word of great and important events di- rect over the radio. If the Federal Radio Commission grants the petition filed by the Na- tional Radio Press Asso- ciation, methods of dissemination of news may be radically altered. However, while radio may change the character of news- papers, it is not believed it will entirely . supplant printed news. Men and Microbes OR the first’time in history, plants and animals have been raised in surround- ings one hundred percent germ-proof. In the Pasteur Institute, Paris, successive generations of tadpoles, guinea pigs, and miscellaneous varieties of insects and herbs grow up without ever having come in contact with a microbe—and thrive. The result is surprising. Microbes are far from as harmful as some people believe them. Some, of course, are responsible for tuberculosis, cholera, and typhoid fever; but others help the baker make bread and the farmer to grow peas and clover. If it were not for such microérganisms as these that cause fermentation, and that live on May, hour ¢ , as in J S LNEwWs) % clock : ae the roots of plants _ them, meal as a ine would probably perish, Wheth, ." en er a human being could os; ae | by isolation from the owen yor billions of microbes, good 4 - ‘tis! bad, that surround him e ee minute is another question, a ’ Curious are the works ¢ four h some of these tiny singl ger a creatures. Just one little mj; all crobe, “‘azo bacter” by name, Our in a sense built the P. once ¥ Canal. Chile saltpeter, frog } Roma which by an indirect proces § run bi the nitroglycerin used to bhy | the mi the canal was obtained, — wasn formed by the action of this} of the microbe upon organic matte, | of En Another microbe lives in the} time mud of swamps and manufy. — three tures marsh gas. It is thy— one h germ that Prof. J. B. S. Hak § clock dane, British biologist, sy § Cante pected of concealing itself, § the ck the moist, dirty subsoil of Lop. don and generating the myst, Wh rious gas that not long ap ‘ blew up a mile of streets Pasteur himself, the greg biologist, doubted that a mgf land, could live if he wer® ergy ‘ wholly isolated from§ that i germs. But othe— weigh workers have helig to rai that man might pw§ of we ioe" long his span of yein§ The i by excluding at leat® ergy ae injurious bacterag zurka The Russian bactes§ strent ologist Metchnikel§ Ou traced the decrep§— engin tude of old age tm down chronic _ poisoning when caused by microbes, § runnt sumir Urge 24-How a Clocks Pix HE Internationlg been eet oe. Astronomicalp the le Union recently adopted midnight as thg portic starting point on the clock instead d ee ] eavi noon, giving the dial twenty-four insteal of twelve hours and abolishing the symg . Wh bols “a.m.” and “p.m.” At the same time has | all transportation companies in Greil By cc Britain were urged to conform to thi expell system. ent t The principal objections against tg meast proposed system in England are thati work would make time-tables more involvig oxide than they already are, and that mudg 8ge: mental arithmetic would have to be dom Suc before telling time by the new clock w sumes be an established habit. ‘f ahou Should such a change ever be intwg S¢ven duced in the United States, ex-servit hand. men would have little trouble gettiif— ®"Y ‘ used to the new ‘system. As all fo Sweer overseas men remember, the twenty-fot y | hour method of telling time is in use@ Vh the railroads of France, Belgium, that many, Switzerland, and Austria. wee from the railroads, however, the twel

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Mar, Igy Ws S and fey sa ish. Wher Could gain ie Swarm gf » 800d anf im e juestion, . works 9 ingh e little pj. 'y ie P, eter, from Ct process ed to blag tained, js on of this iC matter ves in the l manufae. It is this B. S. Hal gist, sys. g itself ip Oil of Lop. the myste, long agy of streets the great hat a ma if he wen ated from ut othe ave held night pro in. of years ig at least bacteria n. bacteri tchnikol decrepi 1 age ‘ poisoning nicrobes, -Hour *ks -rnational 10 mical tht as the nstead d ir instead the sym ume time in Gre . to thi ninst th e that il involved at mud > be dont ck would be int X-Serviet - getting ll forme nt y-fou n use @ im, 2. Asi > twel May, 1929 ; in all of these countries, hour dlock ed rat America. osm d, proponents of the new In it will be easy for travelers to clock tyemselves to realizing that 17:15, Ae als, simply means a quarter past ste the afternoon, that thirteen o clock ive ce y., and 21:55 stands for five min- wren! ten at night. They contend, too, cr the change will facilitate trans- Cosa traveling, especially since the British railroads are planning route con- nections with cross-Channel flying serv- ‘oes, which have to go by the twenty- tour hour system on the European conti- oa ror shift back to the old clock when ing British air. ae es ame one to twelve clock system considered a great advance. The pear as early as 158 B.c., had a clock run by water that told the hours during the night, but a really competent clock was not developed until the second half of the eighth century. Later, King Alfred of England devised a method of telling time by candles, the burning of three inches denoting the passing of one hour. Our present twelve-hour clock was invented by monks in the Canterbury Cathedral, England, at the close of the thirteenth century. Where Our Energy Goes HEN Dr. Carl Tigerstedt of the University of Helsingfors, Fin- land, made tests recently of the en- ergy consumed in dancing, he found that in the waltz a person of normal weight expends enough bodily heat to raise the temperature of five pints of water from freezing to boiling. The Charleston consumes more en- ergy than sawing wood. The ma- gurka stands next to wrestling in strenuousness. Our bodies are internal combustion engines, speeding up and slowing down, but never stopping. Even when we sit still, the engine keeps running, but it is “‘out of gear,”’ con- suming less fuel with decreased wear and tear. By lying quiet, you can save your heart 20,000 beats a day. Some interesting facts about the fuel consumption of this human engine have been discovered. The older we become, the less we burn. Men burn more in pro- portion to their weight than women. If two people are sitting, the taller and heavier one will consume more fuel. Where our energy goes during the day has been fairly accurately determined. By collecting in rubber bags the breath expelled by workers in performing differ- ent tasks, scientists have been able to measure how much energy each kind of work takes. The amount of carbon di- oxide given off by the lungs is a precise gage of the amount of fuel consumed. Such tests show that a housemaid con- sumes more energy than a carpenter or a house painter. Dressing a baby requires seven times as much energy as sewing by hand. Washing takes more energy than any other task around the house, with Sweeping next. Ironing is about half as as washing. When a woman has to lean over a table t is too low, she uses up a quarter again as much energy as when the table 18 of proper height. A farmer's wife who POPULAR SCIENCE MONTHLY Measuring energy expended by a typist at work in an air-tight chamber, by the quantity of exhaled carbon dioxide gas in air pumped from chamber. How Much Do You Know About Electricity? EST your knowledge with these questions, chosen from hun- dreds asked by our readers. You will find a list of the correct an- swers on page 166. 1. What is “‘static”’ electricity and what makes it different from electricity that flows in light wires? 2. How much electricity does it take to kill you? 3. If air is a nonconductor of electricity, how does a spark jump through it? 4. What makes electric light bulbs pop when smashed? 5. Is there electricity in the air all the time? 6. Does insulation keep elec- tricity from running off the wire? . What is the difference be- tween positive and negative electricity? 8. What substance is the best conductor of electricity? “1 —ae OY Engineers of the U. S. Bureau of Standards inspecting a submarine “pad-eye” rescue ring tested by the huge pulling machine at the right. put a pedometer on her ankle found that she averaged from twelve to eighteen miles a day in walking about the house to do her work. Such waste of energy is being conserved in millions of homes by better arrangement of the kitchen and by. the adoption of labor-saving equipment. Making Submarines Safer “"TDDAD-EYES,” the steel rescue rings attached to the hulls of submarines so chains can be hooked on for lifting disabled undersea craft to the surface in case of accident, recently passed strenu- ous tests conducted by the U. S. Bureau of Standards in Washington, D. C. A mighty hydraulic machine, with a maxi- mum pull of two million pounds, was at- tached to one of the rings. As the ma- chine began to pull, a recording dial first showed 40,000 pounds. Quickly it rose to 180,000 pounds. Then the needle ad- vanced more slowly. When it pointed to 480,000 pounds, the plates inside the model submarine hull, to which the pad- eye was fastened, began to buckle. At 530,000 pounds, the eye snapped, but the hull model remained intact. Engineers said that this resistance to 265 tons pull—more than twice that of the world’s largest locomotive—will make the rings equal to any sudden jerk of pontoons during the process of lifting a sunken submarine. The pad-eye is one of the inventions which followed the sink- ing of the S-4 off Cape Cod in December, 1927. Another plan for raising sunken sub- marines passed a successful test by the U. S. Navy off the coast of Porto Rico recently. The S-29, with special valves built into the hull, was sunk in fifty feet of water. Divers, bringing air hose from a salvage vessel above, attached them to the valves. Air pumps then blew the water from the ballast tanks and brought the submarine to the surface. During the

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46 process, other hose carried fresh air to the “imprisoned” crew. Future submarines may be able to travel thousands of miles without coming to the top. Meanwhile, inven- tors are bending theireffortstoward in- creasing safety of under-water travel. How Insects See Us ECENT experiments at Colum- bia University show that the eyesight of bees has been overestimated. Dr. Ernst Wolf and Prof. Selig Hecht discovered after a series of experiments that the bee has only about one percent of the perception of a human being. A human eye has only one lens; those of insects many. A fly, for example, has from 5,000 to 6,000; a dragon fly more than 20,000. Working under a powerful, microscope, Dr. Alfred M. Clough, a British biologist, cut a tiny strip, con- taining forty or fifty lenses, from a house fly’s eye. By means of a specially con- structed camera, he photegraphed objects through the strip. The pictures showed that each lens gives a clear and separate image. Flies, however, he discovered, do not see a thousand swatters when only one is raised. The images reach the brain as one. A similar experiment showed how an Oxford professor looks to a humble glow- worm. Another British biologist, Dr. H. tltringham, made a photograph through a glowworm’s eye, one fifty-thousandth of a square millimeter in size—far smaller than the period at the end of this sen- tence. The prepared eye was mounted on a minute drop of diluted glycerin and the photograph taken through it. It showed that the insect has surprisingly clear sight. Enlarged 500 times, the pho- tograph was easily recognized as that of the Oxford professor by all who knew him. Sugar from Flowers and Medicine from Sugar 'N THE bottom of a test tube in the laboratory of the U. S. Bureau of Standards, Washington, D. C., experi- menters recently examined a bit of starch- like substance extracted from dahlias. What they found may result in thousands of acres being planted with these flower- ing plants and our sugar bowls being filled with a new kind of sugar. The starchlike substance was inulin. An acid treatment changes it into fruc- tose, a very sweet sugar which is more easily assimilated by the human system POPULAR SCIENCE MONTHLY Dr. R. F. Jackson and Dr. Sylvia Goergen, of the U. S. Bureau of Standards, with a tube of inulin, a starchlike substance from dahlia plants, from which they obtained new sugars. Edward H. Hansen, Los Angeles electrical engineer, with his invention called the osciographoscope which, he says, makes possible motion pictures of the human heart in action. than cane sugar. While extracting the fructose from dahlias, Dr. R. F. Jackson and Dr. Sylvia Goergen, of the Bureau laboratories, unexpectedly found a second sugar, called difructose anhydride. It is believed to be composed of two molecules of fructose combined in such close union that acid is unable to convert it into fructose. Other tests have shown that peanut shells and sunflowers are possible sources of sugar. More than fifty sugars, some bitter to the taste, are now known to science. Each is essential to the life of some plant or animal. A few of them have been thor- oughly studied. Others are still a mystery. In the Public Health Service laboratory in Washington, two noted chemists, Dr. Claude S. Hudson and Dr. Eugen Pacsu, of Budapest, Hungary, are studying these sugars in search of new medicines. They believe nutritive disturbances may pos- sibly be cured by their use. Since the Crusades, when sugar first became known in Europe, it has had an How an Oxford professor looks to a glowworm. This remarkable photograph was taken through the eye of the insect in place of a camera lens, by Dr. H. Eltringham, British biologist. May, iy ever-increasing demand. [ fourteenth century in England a cath cost as much as a pig, or as mie carpenter could earn in ten days he in search of sugar and spice that Col ~ came to America, seeking a short to the “sugar bowl” of the Orient Pin Beet sugar, now supplying half world’s need, began to be cultivated gs ously slightly over a century ago. ee leon encouraged its production when allies were blockading the ports of tinental Europe. a Now, it seems likely that Sugar fron | flowers as well as from beets and cane may be placed on a commercial basis within a few years. Heartbeats in Movies N ELECTRICAL engineer, Rg ward H. Hansen, of Los Calif., reports he has perfected a invention by which a motion pictur camera can take photographs of , heart pulsating within a living pe. son. He calls his machine an oscig graphoscope and says it will br about a new system of diagnosis fy heart ailments. The stethoscope records only the soup} of the heart in action. The x-ray alloy; it to be seen, but it does not give any permanent record for study. The ney device, says the inventor, will record th slightest pulsation or change in the heart, so that the pictures, thrown on the sere, can be examined and studied by seven physicians. Considered as a piece of machinery, the human heart is about the most efficient part of the body. It works continuous) for half a century and more, sometime for a hundred years, without stopping to be overhauled for repairs. It is composed of muscles which are extremely tough They expand and contract with rhythmic regularity at an average rate of seventy pulsations a minute. The average lifed an American is now above fifty-five year, In that period his heart will have pul sated two billion, one hundred and forty. four million, two hundred and _ thirty thousand times! It is only 300 years since William Harvey published his discovery of the circulation of the blood, in 1628. In thos three centuries we have learned about the mechanism of the heart. We know that its operation is that of a pump. Eacher pansion draws into the left ventricle, one of the four chambers of the heart, about four tablespoonfuls of blood which has completed its seven-minute circuit of th body and has been supplied with fresh oxygen by the lungs. The blood passe through the four chambers, being forced out into the arteries through the tricuspid valve at the top of the right auricle. And that is about all we really ‘now about the heart. There is still much to learn about why and how infectious and nervous diseases affect its muscles and its valves, throw it out of rhythm, and tend to shorten its usefulness. The most valuable feature of the heart is its elasticity. It will stand immens strain and recover without stopping i work. But just what any given individ ought to do to keep his heart in perfed condition under the circumstances @ which he has to live is something whieh times gener lar co’ is refl muscl violer those

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gar fron | ind OVvies heer, Ei. ected a n picture Phs of , yINg per ill bei NOSIS {oy he sound Y allows zive any The ney cord the 1€ heart, ery, the efficient nuously netimes Ping to | mposed y thie seventy > life of e years, 1 forty. thirty Villiam of the n those out the w that ach ex- le, one *h has of the | fresh passes forced cuspid e. ich to is and nd its | tend nense ig its ridual erfect 2s if vhich May, 1929 earn for himself. Some hearts cach hat 0 ected by nervous strain, to- 9 alcohol, coffee, or even by eggs; others seem to be immune to those things but susceptible to others. Asa rule, the smaller the heart in pro- rtion to the body, the more efficient it ie enlarged heart usually means soft- pad muscles. Nurmi, the Finnish runner, owes his great endurance, physicians say, to the fact that his heart is only about half the normal size and beats only fifty times a minute. A slow-beating heart generally lasts longer than one which pul- sates rapidly; and in general, the muscu- lar condition or “tone ” of the whole body is reflected in the heart’s structure. Soft muscles mean a soft heart, which is why violent exercise often causes the death of those unused to exertion. 100-Story Skyscrapers? ECENTLY it was announced that a R Chicago man, Edward C. Kerth, had invented a new light building tile, bring- ing visions of skyscrapers twice as high as the Woolworth Building. Most of the present materials for which the tile might be substituted weigh 120 pounds a cubic foot. The new product is said to weigh less than twenty pounds a cubic foot. As weight is an important consideration in limiting the height of skyscrapers, Professor George A. Bole, of Ohio State University, prophesies that use of the new material will allow 100- story buildings in the future. The Woolworth Building, in New York City, has sixty stories. The process by which the tiles are made is being kept a secret by the in- ventor. The “mystery clay,” of which they are composed, is made into worm- like strings and compressed into bricks. At first glance, these bricks look like blocks of spaghetti. In the compressed form, the tiles weigh fifty pounds a cubic foot. By a second process, called a “yeast treatment,”” chemicals are used to in- flate the blocks, reducing their weight to between eighteen and twenty pounds a cubic foot. This is accomplished with- out materially reducing their strength, it is reported. If thrown into water, the tiles would float like corks. Their density is less than that of bamboo. Besides being of light weight, the in- ventor says the tile is weatherproof, and will not deteriorate with age. If the ex- pectations for the new tile are realized, the Kerth invention may be the most impor- tant in centures of tile-making, which dates back to the early civilizations of Assyria and China. It may even lead the way to man-built mountains — sky- scrapers a mile high in which workers, breathing the pure upper air, will look own upon cloud banks from their of- fice windows! POPULAR SCIENCE MONTHLY Taking the Moon’s Temperature WO astronomers at Mt. Wil- son Observatory, Dr. Seth B. Nicholson and Dr. Edison Pettit, by means of a minute thermocouple, have taken the temperature of the moon before and after an eclipse. If you placed a single drop of water in one pan of a balance scale, you would have to place a thousand of their tiny instruments in the other pan to strike an even balance! As a result of their experiment, . Dr. Paul Epstein, of the Cali- fornia Institute of Technology, has determined that the frozen Dr. Edison Pettit (left) and Dr. Seth B. Nicholson, astronomers of Mt. Wilson Observ- atory, examining the tiny thermocouple with which they measured the moon’s temperature. surface of the moon was once covered with fiery volcanoes. Experimenting with various materials in his laboratory, he found that pumice, of volcanic origin, cooled at approximately the same rate as the moon when placed under laboratory conditions similar to those on the moon when it is in the shadow of the earth dur- ing an eclipse. From this he deduced that the features of “the Man in the Moon” Dr. H. H. Sheldon (left), New York University physicist, measuring ultra-violet rays of the sun that filter through New York’s smoky air. Edward C. Kerth with samples of his light new building tile, showing how it looks before and after inflation by a novel “yeast treatment.” which we see are mountains of vol- canic origin. Each part of the globe has its leg- ends about this imaginary man. In China, for instance, he is supposed to govern marriages, tying together young men and maidens with an in- visible silken cord. In New Zealand, he is supposed to be a native who stum- bled at night and sprained his ankle, and lamented so loudly the moon came down and sailed back into the sky with him. For such legends the delicate instru- ments of astronomy are substituting fas- cinating new facts about the moon and its features. Sifting a City’s Smoke R. H. H. SHELDON, New York University physicist, is mapping the spectrum of sunlight in different parts of New York City to determine the amount of ultra-violet rays that come through the smoke and dust in the air. City dwellers, feeling their backs warmed by the sun- shine, imagine they are getting the full benefit of sunlight. Tests prove, though, that the infra-red, or heat rays, rather than the ultra-violet, or health rays, are the ones that most readily break through dusty air. At ten o’clock in the morning on a cer- tain day not long ago, a cubic inch of air over London, England, was found to con- tain 340,000 particles of soot! So fine are such particles that about ten thousand of them are required to form a speck weigh- ing one milligram, or one-four-hundred- and-fifty-thousandth of a pound! Yet, Dr. J. S. Owen, of the British Meteoro- logical Office, estimates that the number of soot particles which Londoners breathe in one hour would, if put end on end, circle the globe 2,500 times! Winds carry smoke and dust from fac- tory districts hundreds of miles. After volcanic eruptions, dust particles often travel around the world. An April dust shower that is estimated to have dropped 1,800,000 tons of dust over Europe was traced to high (Continued on page 161)

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Se POPULAR SCIENCE MONTHLY Real Fathers of F lich Honored by Kings and Feted by Royalty—Another Absorbing Chapter in the Inside Story of Wilbur and Orville Wright By JOHN R. McMAHON Ma , Wilbur Wright in his prime. This photograph was taken at about the time he was flying before kings and being sought by nobility. After Mr. McMahon had completed this article, came word of the death, in Kansas City, Mo., of Mrs. Henry J. Haskell, formerly Katharine Wright, sister of the inventors of the airplane. Throughout their early struggles, it was the loyalty and devoted aid of their be- loved ‘*‘Sterchens,”” as related in this story, that carried Wilbur and Orville Wright from disappointment to the eventual triumphs in which Katharine shared.—Tue Epitor. _ OUR Majesty, may I present the Wright brothers of Dayton, Ohio?” “This is an honor and pleas- ure!” exclaimed Alfonso of Spain, smiling as he shook hands vigorously with Wil- bur and Orville. “What a marvelous invention your airplane is!” The brothers grinned politely and bowed a trifle. “T would ask the great privilege of a trip in the air,’ continued the young monarch, “except for one thing—” “What is that, Your Maj- esty?” delicately prompted @ courtier. “My Queen and Cab- inet made me promise not to do it!” said Alfonso with a. rueful laugh in which the little group of notables on the flying field at Pau, France, discreetly joined. “Yet they say a king can do as he likes.” If a scene like this had The excited Frenchman exclaimed: “The French government buys the Wright plane for one million francs. Wilbur messed frequently with Italian officers and claimed he set a record by devouring “forty-seven miles of macaroni.”’ been visioned in ateacup by Sister Katha- rine half a aozen years earlier, Wilbur and Orville would have said, in effect: “Not a chance, Sterchens. Maybe we'll get into a circus sideshow, unless we're just embalmed in a scientific en- cyclopedia.”’ In fact, the virgin flight of the airplane at Kitty Hawk on But-—” King Victor Emmanuel of Italy, camera in hand, with Orville and Wilbur at Rome in 1909. December 17, 1903, had buried - the inventors under a mas of ribald publicity. Europ learned some of the facts first when Octave Chanut lectured before the Aen Club of France, telling about the remarkable feats of his young friends, the Wrights, and showing pictures of their glider. Thus the French early began to annex the invent They were frank about. it, calling their machines “‘the Wright type.” However, they bungled in the absence d a model and air table figures giving the proper curves for wings and propellers. The world’s first regular flying field was an eighty-acre cow pasture eight from Dayton. Here, in 1904-5, th brothers developed the airplane, i hundreds of flights when no other humaa The Empress of Germany watching a flight of the Wright mae chine in 1909. The Kaiserin is seen standing in the back of the royal car. European royalty flocked to see these early flights.

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d buried & mas Europe 1e facts Chanute e Aen ig about s of his Vrights, of their ch early vention, out - it, L type.” sence of ‘ing the ellers. eld was t . miles 5, the human ; ew at all. They learned to steer pss wat steadily increased their own records of distance and duration. Local reporters were invited to witness the first attempts and these being failures, the writers decided not to waste time on the “airship.” They thought it was a dirigi- ble balloon. E British war department sent an agent to investigate the new vehicle in the fall of 1904, which prompted the Wrights to offer it first to Uncle Sam. Our war department was not interested. When Wilbur the next year made a record of twenty-four miles in thirty-nine min- utes, the French government became in- terested and sent a scout, followed by a military commission, to Dayton. Mean- while the brothers again offered the air- plane exclusively to our war department and again were rebuffed. “There is no such animal as the air- plane,” intimated in effect the military experts at Washington. The foreign copyists became busy. The first of them to make a seeming success with a near-plane was San- tos-Dumont. He devised a _ T- shaped box kite affair, added a powerful motor, and in November, 1906, made a straightaway hop somewhat shorter than the Wrights’ epochal first flight three years earlier. In early 1907 the Aero Club of — America, with numerous millionaires in its membership, opened a sub- scription to pay Wilbur and Orville $100,000 for their patent rights in the United States, which would then be turned over to the Government or re- leased to our home public. In six months a total sum of $11,000 had been raised. Men were still skeptical. Our war department, prodded by Presi- dent Roosevelt, now wrote to the inven- tors, asking: POPULAR SCIENCE MONTHLY “What price air- plane?” “To Uncle Sam—now —$100,000,” replied the brothers in effect. The officials said they re- gretted they did not have that much money to spend, whereupon the Wrights agreed to supply a plane on feasible terms. Around this time the machine seemed to be sprouting golden wings. A French syndicate Jimmy Hare, veteran war photographer, was so amazed when the un- earthly bird roared past him that he forgot to click the camera shutter! headed by M. Deutsch, oil magnate and balloon patron, came within an ace of buying the European rights in the invention for $750,000. Intrigue spoiled the arrangement, but 4, a new deal was launched for the sale of the air- plane to the French { government. The brothers were together in Paris in midsummer of 1907 to con- summate the _ transaction. The price was fixed at one million francs. © Illustrations Bureau The brothers explaining their machine to King Edward VII of England at Pau, France. Wilbur is in foreground, Orville at left. The King (wearing derby) seemed to have little interest. Orville Wright as he looks today. A recent photo- graph, taken 25 years after the first airplane flight. A British war department agent paid a visit. This prompted the Wrights to offer the machine to Uncle Sam. 49 At last the budget committee of the war department met to act. The expectant Wrights awaited the decision in their hotel room. The door was flung open. An excited man slammed the door, hesi- tated, then exclaimed: “Tt is all right! Everything is going through. The French government buys the Wright machine for one million francs. But—there is one little thing to be done... .” The brothers calmly waited for the em- barrassed spokesman to continue: “47 OU will get your million francs, all right. No trouble about that. It is, just that it is necessary to make a change in the wording of the contract, so that you ask one million two hundred and fifty thousand francs. Then it will go through this afternoon. And you will get your million francs.” Wilbur and Orville kept looking at the speaker. They acted as if they were deaf or did not quite under- stand. They were in dire need of money. So far, four years after their invention, it had yielded them no profit. Indeed, it had swallowed their savings and lately had put them in debt to their sister Katharine, who had mortgaged the Hawthorn Street home, then owned by her, in order to aid them. A million francs—$200,000—would wipe out the mortgage and every other care, and give independ- ence for a lifetime of absorbing exploration in fields of knowl- edge yet unknown. “Orville and I have no objec- tion”—Wilbur spoke in quiet staccato—“to the terms. That is, with the understanding that the contract names the man who gets the additional two hundred

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The high and mighty of Europe vied for the honor of pulling the rope which hoisted the heavy weight of the launching derrick. I and fifty thousand francs and states his position on the budget committee.” And so the provincial Yankees lost their million francs! Meanwhile copyists were busy with near-planes. Delagrange hopped. Henry Farman, adding ailerons to a Voison .ma- chine, made a straightaway flight of half a mile in October, 1907. Wilbur was on his way to St. Peters- burg in August, thinking optimistically that. rubles might contain less alloy than francs, when he found another opening at Berlin, and was joined there by Orville. German officials agreed that if the brothers actually flew a machine in their presence, the Imperial German govern- ment would do business. HE inventors returned to America in the late fall and took up with our war department the building of a plane for Uncle Sam. A contract was awarded to the Wrights at their figure, $25,000. The Aerial Experiment Association, headed by Alexander Graham Bell, began work. Its director of experiments was Glenn H. Curtiss, motorcycle rider and engine builder. Its secretary was Lieut. T. Selfridge, who wrote to the Wrights on Jan. 15, 1908, asking for elementary in- formation to be used in building gliders. The brothers complied. The remarkable success of this group at Hammondsport, N. Y., in advancing from the kinder- garten stage of gliding to the creation of a power-driven airplane within five months, caused some persons to believe that an independent discovery of the secret of flight. eclipsing the Wrights’ in celerity of results, had been achieved. Fortune began to smile on the harassed inventors this year after the defeat of many dazzling hopes. Millions of francs had fluttered before their eyes, and van- ished. But now there was a prospect of Katharine Wright seated in the ma- chine with her brother Wilbur after he gave her a surprise by taking her for a flight before the King of England. real money from Uncle Sam. And in the win- ty ee\c¢ ter the brothers learned 4 EE that their patents in 5 LE \ France had been sold to a syndicate headed by the once-scared-out oil man, M. Deutsch. “We get half a mil- lion frances, Orv!” I hear Wilbur saying. “This time they're real, not the funny ones. One hundred thousand dollars. We can use it. I guess we ought to celebrate. How about some broiled porterhouse steak for dinner?” The payment was $35,000 in cash and the balance stock. The contract called for an hour's flight in France and the teaching of three pupils. It was agreed that Wilbur would be the one to go abroad to fulfill these terms while Orville would stay at home and look after the deal with Uncle Sam. In May, 1908, the brothers went to May, 1999 Farman was performing in France Delagrange hopped nearly eight miles gt Rome. The first time in history that a plane carried two persons was on May 14, when the brothers ascended in turn with a pas- senger, Charley Furnas, whom they had brought to Kitty Hawk as their me chanic. Orville took Furnas on a jaunt of two and a half miles. A number of press writers lurked be. hind the sand dunes during these tests, Among them was Byron R. Newton, later Collector of the Port at New York, whose employer, James Gordon Bennett, pro. prietor of The Herald, had commanded: “Q'HOW up those fakers—the Wright brothers!” This was a difficult assignment for him as for Arthur Ruhl and for Jimmy Hare of Collier’s Weekly, a veteran war pho- tographer who had kept his nerve amid scenes of carnage, but was so amazed when the unearthly white-winged bird lifted from the sand and roared past him overhead that he forgot to click the shut- ter of his aimed camera! On his way back to Dayton to complete the new machine for the Government, Or- ville scouted the test grounds at and around Ft. Myer, Virginia. This suburb of the national capital had few merits as a pioneer air port. A hazardous course was laid out amid barracks, car lines, tele- graph poles, ravines, and wooded hills, with no clear or level spots for emergency landing. With small power and scant altitude, an embarrassed plane would have no chance to glide to safety. Prob- ably a modern pilot with equal equipment would decline to accept the risk. The in- ventor knew the peril and calmly staked his life on the outcome. The first formally public flight of the Wright machine in America was made at Ft. Myer on Sept. 4, 1908. It was a very brief try-out. When Orville stayed up four minutes next day, “the crowd went crazy.” They had reason to be crazier on September 10 when Orville flew almost an hour in the morning, and in the afternoon circled the parade grounds at 120 feet altitude for an hour and five minutes. The lat- ter was a world record, since Wilbur in France was having motor trouble and no (Continued on page 136) Four days after the accident Orville, in the hospital, was cheered by news of Wilbur’s The one’ disastrous flight of Orville’s career—wreck of the Wright plane at Fort Myer, Va., in 1908. Lieut. T. Selfridge was killed and Orville injured. Kitty Hawk, scene of their im- mortal discovery, to do somé practice flying with the 1905 plane, now fitted to carry two persons and with the controls changed so that the pilot would sit upright instead of lying prone. It was high time for the in- ventors to show the world what they had, for with near-planes world’s record flight. ——mep Oost _ _— —_ ~~ oes GO ete

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t, pro. anded: Vright or him Hare ' pho- amid nazed bird t him shut- plete t, Or- and burb asa was tele. hills, ncy rant ould rob- lent in- ked the - at ery up ant on er »st ig, ed 20 ur t- d, aS d ) ie ie May, 1929 Strange Eyes That Never EN Televox, the me- chanical man, was first *“*born,”’ he had the sense of touch. Later he was en- dowed with hearing, then with a voice. Now it is announced that, thanks to electric eyes, he is to ss the sense of sight as well! Marvelous light-sensitive electric cells, more responsive than human eyes, are being put to amazing new uses in factories, offices, and homes. This absorb- ing article tells how they can put out fires, detect burglars, sort cigars or yeast cakes, and perform all sorts of magic to relieve us of tedium and drudgery. By ARTHUR A. STUART N A New York lecture platform, the other night, a young man tossed a match into a pan con- taining gasoline and kerosene. From the seething flame arose black clouds of smoke, whirling through an in- conspicuous beam of light that passed above them. Then a faint click—and -fire-smothering gas belched from a cyl- inder standing near by. Instantly the fire was out. An “electric eye” had perceived the first wisp of smoke and had turned in an alarm that set off the extinguisher. So practical is this watchful electrical fire warden that soon it may be widely, used to protect large rooms and offices. In- deed, an eastern manufacturer of fire protection devices already is pro- ducing the outfits in quantities for commercial use. Not a new device is the “elec- tric eye,” the photo-electric cell. This versatile robot, that obligingly releases a flow of elec- tric current whenever a beam of light falls upon it, sits in a thea- ter’s projection room and controls the voice for the talking movies. When photographs are dispatched by wire or radio, the electric eye is called into service. Television would be impossible without it. But some of its newest magic almost transcends the imagina- tion. It can detect burglars that step past an invisible ray and give the alarm; it rejects defective articles on a moving factory con- veyor with uncanny accuracy; it can count people or automobiles with unflagging exactness by the shadows they cast upon it. Some of these wonders were demonstrated recently by John V. Breisky, research engineer of POPULAR SCIENCE MONTHLY ee A robot inspector! When wrapped yeast cakes, on a moving belt, pass under the scrutiny of this “ elec- tric eye,” those without the proper labels are automatically knocked off the belt as if by magical hands. the Westinghouse Electric and Manu- facturing Company, at a meeting of the American Institute. He placed a dozen wrapped yeast cakes on a moving belt. Three of them bore no yellow trademark, and the bright wrapping of tinfoil stood out in marked contrast to the rest. While Breisky turned a crank, the yeast cakes paraded in single file beneath an electric eye. The first one passed it. So did the second and third, without incident. Then came the fourth, with no label. A little gasp arose from the spec- tators. Deliberately a metal arm had If the paper breaks as it passes over the rollers of a paper-making machine, this experimental light-sensitive cell instantly stops the machine. The light source is seen at the right, below the paper. swung down, without human interven- tion, and pushed the defective package off the belt! Repeatedly the device passed properly wrapped packages, to swoop down upon those with m/ssing labels and summarily deposit them in a rejection box. Such a device, Breisky pointed out, may prove of revolutionary importance in industry, where inspectors now must sit all day watching for faulty articles that pass them on a swift-moving belt. An electric eye, that “never gets tired,” could replace, them with its superhuman infallibility. Meanwhile another electric eye, stationed at the doorway of the dining room at the New York demonstration, had carefully éounted the 200-odd guests as they stepped past the intangible barrier of a ray of light. Every interruption of the beam, which fell upon the sensitive eye, was accompanied by a click of the counter. N A theater or a public hall such a device would register the number of patrons automati- cally, even without their knowing it, for it is not necessary to use an ordinary beam of light. In- visible rays, such as “ultra- violet” or “black” light will serve as well. Electric cells may be made that are sensitive ex- clusively to these rays. And this possibility leads to another sen- sational application. From a lamp carefully screened to appear pitch-dark to the eye, an invisible beam of ultra-violet

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52 light may be shot squarely across the front of a safe or bank vault to serve as a burglar alarm. The moment an intruder steps in front of the beam and casts his shadow upon the sensitive cell, upon which the beam is trained, a distant alarm is set off, unknown to him, and the police will arrive in time to catch him red- handed. Other remarkable devices using the new magic soon are likely to become standard tools of industry. Smoke re- corders, now in commercial operation, are only samples of what is to come. OT long ago one of the world’s largest bank note printers inquired if an “electric eye” apparatus could be built to solve two of its peculiar problems of guarding against counterfeiters. In mak- ing bank notes, every scrap of the special paper used must be counted at each stage of the printing to assure that none falls into the hands of rogues who might print spurious notes upon the genu- ine paper. Engineers responded by demonstrating an electric machine that would automatically register, by their shadows, the number of sheets of paper passing a given point. ‘The second problem solved was that of matching colors. The more accurately this concern could print notes in uniform colors, the harder it would be to counterfeit them; for a fake of slightly different shade could instantly be de- tected. Again engineers perfected a light- sensitive cell that could detect and record, in terms of electric current, the slightest differences in the colors of printing inks. Sorting cigars is an odd job of the elec- tric eye. Buyers of cigars insist that the top row in a box shall be of uniform color; therefore manufacturers have sorted cigars by hand into different colors. Trained workers can distinguish seven different standard shades. Now an elec- tric machine is being developed which will sort cigars of ten different shades. As this is written, engineers of the Hol- land Tunnel, the great vehicular tube under the Hudson River that connects New York City with New Jersey, are testing the installation of a newly- developed eye, buried in the pavement, that automatically counts cars passing A robot that puts out fires, demonstrated by John V. Breisky, West- inghouse engineer. When he tosses a lighted match into a pan of gasciline and kerosene, the smoke is detected by an electric eye (at It automatically releases a stream of fire-smothering gas which extinguishes the flames. left) illuminated by light beam (right). the Hudson River, New York. The shad- ow of each car, inter- cepting a beam of light, causes a photo- electric cell in the pavement to operate a counting machine. Below: An operator, watch- ing the telltale dial of the automatic counting ma- chine, can tell at all times the volume of tube traffic. over it by responding to their shadows. The complete apparatus proposed, a tri- umph of mechanical ingenuity, will serve the double purpose of registering the total number of cars using the tunnel in a day and showing at a glance just how many cars are in the tunnel at any moment. R the latter purpose, a special counter will be used, kicked forward by every car passing over an electric cell at the tunnel entrance and backward by each car that, leaving the tunnel, darkens another “eye.” Subtracting the cars that have emerged from those that are entering gives the total number in the tunnel, which serves as a constant check on the indicators that register the fresh- ness of the tunnel air. An elevator manufacturing concern is considering the use of an electric eye that would prevent auto- matic doors from clos- ing while a person is stepping through the door. A beam of light shot across the entrance would give the means of control. Other novel uses have been suggested. Elec- tric eyes in subways would do away with tally keepers now sta- tioned in underground booths to note the arrival of trains, for trains would literally be made to punch an automatic time clock at each station. In this case the eye would be buried in the middle of the track and operated by a light overhead. Coupled with a railway signal, an electric eye may safeguard passen- gers through a new British inven- tion. In London a model railway is being demonstrated in which a train running past a danger signal is stopped without the intervention of any human hand. A beam of light is shot squarely across the track, falling on the sensitive cell; if interrupted by a passing train, the action of the cell is determined by the position of the signal. A “clear” signal permits the train to pass; but a “danger” indication causes the eye to spring into action and, through electrical contacts, to slam on the train’s brakes. Such a device, it is pointed out, would make collisions impossible even if the engineer of a speed- ing train were to lie down in his cab and go to sleep! Smoke-recorders using the eye may now be purchased. Mounted in a smokestack of an industrial plant, they warn of wasted fuel, as indicated by the smoke, and of air pollution, either by making a record on a chart or by ringing an alarm bell when smoke thickens. In every one of these applications, the “electric eye”’ itself is a small glass bulb resembling an ordinary radio vacuum tube. One side of the bulb is coated with a thin film of light-sensitive metal—such as potassium, sodium, or caesium. This is the coating that gives the bulb its magical properties, for when’ a beam of light falls upon it, a stream of electrically charged particles shoots from this coating to a ring of metal at the center of the tube. If electric wires are connected to both the coating and the metal ring, a current flows between them as long as the light beam keeps the space filled with the charged particles. Coupled in an electric circuit, such a “‘photo-electric cell,” as engineers know it, performs all the won- ders that have been described, for it makes and breaks the circuit in response to light and shadow. In inspecting yeast cakes, for instance, the light reflected by a tinfoil wrapper actuated the cell and, through it, an electric rejection lever. In counting persons who interrupt the light beam, the opposite effect occurs. The electric circuit is (Continued on page 152) Lc Al _ - _ . 2 aeons @fe ea aa a

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MAY, 1999 ulb um ith ich his its lly , provide the best balance during the voy- May, 1929 F POPULAR SCIENCE MONTHLY 53 Steamer Carries a Mile of Cars Loaded Freight Train, Hoisted OOF LOCKING CARS IN PLACE Je Aboard by a Mammoth Crane, Is Swallowed by Ocean Ferryboat ? \ CHART AND WIRELESS ROOM train almost a mile How freight cars LOADED are loaded and dis- long disappears into the hold of tsthetell an tradie a monster ocean ferryboat, two in the hold and thirds the size of the liner Mau- decks of the See- ° : train. Inset shows retania, which recently began satel a techs epuaing between On a _ _ the cars in place. Line ie WON 5: na, Cuba. e freight cars, haulec ee o° the dock alongside the Seatrain, as the ease eeten prods an vessel is called, are picked up in cradles FORWARD PART OF HOLD by a giant crane and lowered into the PORTABLE STANCHIONS...__2.--— re hold. The capacity of the loading ma- WHITE CHAINS chine is a car every six minutes. Each time a car is placed aboard, another {iGuTs Nag BOILER) GALLEY CASING SKYLIGHT. ER DECKS 1 ARE WATER-TIGHT, SERV ENGINE ROOM “j--~ S& ye an ) SKYLIGHT \ # . ? HATCH COVERS, CABIN. > eae ate REE DECKS || Ni WITH FOUR tte Seip CKS EACH. CAPACITY “FS 2S 95 CARS Ay - UP AGAINST MAIN SUPPORT” WHILE SHIP 1S DOCKING can be removed on the return trip of the Below is a photograph cradle. Thus one shipment of cars can be of the i load- ° ° ing crane hoisting a car unloaded while another is placed aboard. Pr aber Se eg In ten hours, 190 cars, with loads ranging The design and opera- from fifteen to twenty tons, can be han- tion of the crane are pictured at the right. dled at the terminal. Inside the Seatrain four decks, each having four parallel tracks, hold the cars. The capacity of the ship is ninety-five cars, virtually a train a mile long. They are distributed in such a manner as to sixty-two feet three inches. Its steam engines, burning oil fuel, develop 3,000 horsepower and drive the single-screw ves- sel at a service speed of eleven knots an hour. The new Seatrain service allows freight to be loaded in cars at factories in American cities located at a distance from the sea and sealed until it reaches its destination in Cuba. It saves the expense of handling and rehandling the contents of freight cars at the This Leviathan of ferries was built in steamship piers and protects Scotland at a cost of about $700,000. Its the packages from breakage length is 427 feet six inches: its width and pilfering. age. Twenty-six are placed in the hold, twenty-six on the second deck, thirty on the upper deck, and thirteen lightly- loaded cars on the superstructure. When they are lowered into the hold to the level of the track, a mechanical puller draws them into place. To prevent the cars from rolling or tipping in heavy seas, the wheels are braced at each end by special bumpers, while steel arms, locked against the side of the cars, prevent them from rocking.

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54 OWING the underwater meadows of LVL the sea is part of a process which is providing a new kind of fodder for live- stock. Kelp, formerly collected for the extraction of its iodine and potash before rore economical methods of obtaining them were devised, now is being harvested, ground, dried, and fed to farm animals to supplement the grain and hay harvested on solid ground. This undersea vegeta- tion is employed also as a fertilizer. A unique marine mowing machine for cutting the kelp was demonstrated re- cently in Los Angeles Harbor, Calif. It consists of a scow, at the prow of which a machine resembling a hay loader descends into the water. This is an inclined frame over which passes an endless belt of spiked crosspieces. At the bottom sharp blades shear off masses of the seaweed. These catch upon the crosspieces and are elevated by the moving ladder and de- Fishless ‘*Cod Liver’’ Oil Made from Yeast (= liver oil is now being produced A without the help of codfish by a process perfected by Dr. Charles E. Bills, of Evans- ville, Indiana. The power of cod liver oil to build bones and prevent rickets is at- tributed to the presence in it of a chemical substance, ergosterol. This substance is also found, in an inactive state, in yeast and in certain fungi, and can be made active by exposure to ultra-violet rays, either from the sun or from artificial sources. The yeast ergosterol is then dis- solved in peanut and cottonseed oils. Besides being without an unpleasant taste, the new product, it is said, will not spoil or become rancid. No Sterilization by Radio i; Y A false analogy between radio waves and X-rays some alarmists have been concerned as to the effect of radio upon the fertility of the human race. It is well known that X-rays have the property of causing sterility, but experi- ments on mice by Drs. Nemours-Auguste and Martin, of Paris, who recently re- ported their conclusions to the French Academy of Sciences, indicate that radio waves have no such effect. Mower Harvests Fodder from the Sea Bottom POPULAR SCIENCE MONTHLY posited on the scow. The ocean harvest, as it comes dripping from the water, is piled in the hayracklike deck compart- ment of the scow. This sea-bottom food, rich in iodine and potash, is expected to prove a valuable addition to the diet of farm animals, and even to rabbits and poultry. Tests of its beneficial effect upon different kinds of animals are being made in a Los Angeles laboratory, where rats are being fed the new diet. The dried seaweed is added to their rations in various quantities, and at regular intervals the animals are subjected to an examination and weighed to see how the food is agreeing with them. The Air Above Your Home Is Yours, Say Experts F YOU own a piece of land your owner- ship extends down to the center of the earth and up to the sky, according to the National Association of Real Estate Boards. You may sell or lease the air above your land property, it contends. Many legal authorities, however, are modifying their belief that a landowner can stop strangers from flying over his land. They insist the air is analogous to navigable water and that flying cannot be interfered with as long as it does not in- jure the property in any way or prevent the owner from using it. Italy Originator of Ice Cream? HE honor of originat- ing ice cream is claim- ed by Italy. Records at Florence are said to show a thriving ice cream busi- ness flourished there in the sixteenth century and, when Catharine de Medici journeyed from Florence to France, it is recorded that she took her own “gelateria,” or freezing plant, along. By 1775, the dessert was known in France, England, and Germany. The first advertisement of Left: The strange mowing machine harvesting sea- weed from the bottom of Los Angeles Harbor, Calif, Above: Weighing rats to see effect of kelp diet. May, 199 ice cream in New York appeared June §, 1786. The delicacy was introduced to Washington by the widow of Alexander Hamilton at a dinner in honor of Presi. dent Jackson and the first wholesale ice cream business was started by Joseph Fussell, of Baltimore, in 1851. ‘*Wishbone”’ Tubes Detect Approaching Vessels A “FLOATING wishbone” is the lat- est safeguard for vessels against sub- marines and other ships approaching through fogs. The strange detecting in- strument, resembling a robot with bow legs, is formed of a combination of tor- pedo-shaped tubes. It is lowered into the water attached to an electric cable. When a submarine or other vessel ap- proaches within a certain radius, it sets up vibrations in the sensitive instrument, which sends electrical impulses through the wire to recording instruments on board the ship to which it is connected. Two of the detectors were tried out with success recently at Boston, Mass. Taken beyond Boston Light on board a power boat, they reported the approach of every vessel. In case of war, the inventor claims, the instrument would detect sub- marines approaching troop ships. Launching two of the detectors from a power boat during recent tests at Boston, Mass. They signal approach of another vessel. ae oe ee | —s me ole eet sO OL ae ee ee alin tee a eee ee ob

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May, 1999 diet. June 8, uced to exander f Presi. Sale ice Joseph ‘tect is the lat. ist sub- aching ‘ing in- h bow of tor- nto the sel ap- it sets iment, 1rough its on ected, d out Mass. yard a ach of yentor t sub- May, 1929 Mothering a Brood of 12 Submarines IKE a hen with a flock of ducklings, L the Holland, mother ship of a dozen JJ. S. submarines, watches the under- water boats disappear below the surface of the ocean and waits in position for their return. The vessel, named after J. P. Holland, the American in- yentor of the submarine, * mothers ten of the speedy little “S” type submarines and a pair of the “ grown-Up ” undersea ships of the a td type. : How the vessel. appears with its steel brood clustered beside it is shown in the photograph taken from a plane circling overhead. The crews are seen standing at at- tention in readiness for the signal for maneuver practice. The Holland has been stationed in the Pacific, off California. Blades Cost Shavers $38,000,000 a Year ORE than $38,000,000 worth of safety razor blades are made in the United States each year to replace those dulled by all kinds of beards, a report of the Department of Commerce reveals. During the same period, $1,250,000 worth of razors to hold the blades came from the factories. That straight-edged razors are still in demand is shown by the fact that more than $300,000 worth are manufactured every twelve months. Pocketknives reach a total of more than $5,000,000, while scissors and shears are only $1,000,000 behind. How Airplane Carrier Crews Keep Fit EN who care for the war eagle nests of the U. S. Navy have to; keep in good physical condition. Early every morning the men of the airplane carrier Saratoga line up on the huge landing deck of the vessel for calis- thenic exercises. The Saratoga, sister ship to the Lering- ton, can carry forty combat planes and One of the world’s biggest exercise classes going through its morning drill on the spacious upper deck of the U. S. airplane carrier Saratoga. POPULAR SCIENCE MONTHLY om The inventor with a model of the new elevator, show- ing how it transfers grain from ships to railway cars. thirty-two bombing machines. It is elec- trically driven, and all the turrets, bridges, and funnels are placed at one side, leaving a spacious deck clear for the planes to land and take off. The electric current used to run the Saratoga could light a city the size of Boston, Mass. Onion’s Light f Photographed iy N ONION ss sup- 4 plied the light for an amazing photograph recently reported to the Society of Ameri- can Bacteriologists. To prove a theory that. growing plant tissues emit ultra-violet light capable of stim- ulating cell divisions and growth, Ralph R. Mellon, N. von Ra- shevsky, and E. von Rashevsky, of the In- P | stitute of Pathology, 4 Western Pennsylvania ' Hospital, Pittsburgh, photographed the light. 3 Remarkable aerial photograph of the mother ship Holland with her brood of submarines in the Pacific. New Grain Elevator Weighs Cargoes Automatically RAWING a stream of grain from the hold of a vessel on one side, auto- matically weighing it, and loading it into freight cars on the other side, a new ele- vator, designed by Joseph A. Schmitz, of Chicago, IIl., is expected to save time and money for grain dealers. It will allow steamers on the Great Lakes to transfer their cargoes directly into the railroad cars by way of the elevator, at the same time keeping a record of the amount of grain transferred. An inclosed conveyor, which lifts the grain into the bins of the elevator, can be raised and lowered as one compartment of the ship is emptied and the vessel is warped ahead for an attack upon the next compartment. A model of the in- vention, shown in the picture at the left, has been exhibited in the weighing de-. partment at the Chicago Board of Trade, where the inventor is weighmaster. Three Men Have Wild Ride in Runaway Balloon RUNAWAY balloon recently carried three Germans on a wild, uncharted flight across Holland and the North Sea and landed them near Aberdeen, Scot- land. The occupants were a farmer, a dentist, and a doctor. Soon after taking off, near Leipzig, they discovered that the valve for releasing gas to bring them to earth had stuck, and that they were at the mercy of the elements. During the night, they were swept over the North Sea and driven along the coast of England. A shift in the wind would have carried them out over the Atlantic. At three o'clock in the morning, they sighted a light, which proved to be Aber- deen, but the gale whirled them away in the direction of the snow-covered crags of northern Scotland. As the hydrogen gas seeped through the envelope of the bal- loon, it sank nearer the earth, the basket finally catching in a tree on the top of a high hill. This allowed the occupants to climb to the ground in safety.

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56 Pictures in Wood Etched by Sand POPULAR SCIENCE MONTHLY

INE grains of sand etch pictures on large panels of Douglas fir in a new process developed recently by a Long- view, Washington, lumber company. The pictures, called xylograves, will decorate the waiting room of a railway station in the Pacific Northwest. In making the unusual pictures, sten- cils are placed over the panels before they are submitted to the etching treat- ment. A stream of eroding sand grains is then played over the panel, eating away the soft grain deeply and accentuating the hard, but not affecting the wood covered by the stencils. Thus, when the etching process is complete and the sten- cils removed, the design stands out in relief with a background of raised and lowered lines of wood. Life, color, and perspective are added by stains and wax. By another method, the natural grain «4 > » Lower «<ais ae om +e ‘pele: ‘ patterns found in slash grain Douglas fir are etched into relief. This process scours out the soft wood, emphasizing the innate artistry of the hard grain figures. It also gives the completed panel a worn, mellowed effect similar to that of pieces of driftwood. The scenes depicted in the panels for the. railway station include a logging scene and two mountain views, one of Mt. Baker, the other of Mt. Shuksan, both in northern Washington. They are framed with fir figured by etching. Crests, fraternal insignia, and panels of ornamental scrollwork of unusual ap- pearance are created by a similar process on cedar lumber. The cedar is adaptable to exceptionally deep etching that em- blazons the design in high relief against background of straight grain which wears down unevenly.

The wonderfui chrysanthemum plant, with its pyramid of 523 blossoms, all growing from a single stem. It was grown in Japan. A framework of bamboo holds the stalks to form the pyramid. May, 1999

A fraternity crest etched in straight- grained cedar lumber by the new process, Stencils were used in order to make Two beautiful mountain views etched by sand in Douglas fir. The wood frames also are figured by etching. the crest stand out in bold relief,

Women Drivers Have More Accidents, Survey Shows F YOU ride with a woman driver, your chances of being in an accident are three times as great as if a man is at the wheel. At least that is the conclusion arrived at from a survey covering eleven months, made recently by Dr. Morris S. Viteles, Assistant Professor of Psy. chology at the University of Pennsyl- vania, Philadelphia. The accident records of a taxicab com- pany employing 150 women and 2,000 men were examined. All the drivers operated the same kind of cars under similar conditions and had the services of the same corps of shop mechanics. Yet the records showed that the women drivers were in three times as many acti- dents, in proportion to their number. These accidents, however, were rarely as serious as the ones occurring to taxis driven by the men. On the other hand, Dr. Viteles pointed out, the overcautious- ness of the women often resulted in crashes by other drivers. 523 Chrysanthemums Bloom on a Single Stem VE hundred and twenty-three chrys- anthemums growing on one plant! With the nourishment brought from the ground by a single stem, a prize plant, belonging to the royal family in Japan, produced a whole roomful cf blooms. A framework of light bamboo held the stalks § in such a position that the plant appeared ‘ to be a huge pyramid of shaggy flowers. Japan is noted for its chrysanthemum beds, some of the finest being found in the Hihiya Park, in Tokyo, where the unusual plant with its half-thousand blooms attracted crowds when it was ex- hibited recently. The chrysanthemum originated in the Orient. They were first found in China.

May,

side cons appt ever on | ovel in a belt mer

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process, > make relief, Vlore WS Tr, your ent are | at the clusion eleven Morris f Psy. nnsyl- D com- 2,000 drivers under TViCes vomen y acci- mber. ely as tious- od in May, 1929 i , Back Yard Observatory Built of Wall Board Y TAKING a few steps from his back B door, Robert E. Millard, of Portland, Oregon, enters a remote world of _ Stars and planets. He has constructed in his own back yard what he believes to be the only privately owned observatory on the Pacific coast. Housed within it is a four- inch refracting telescope which brings many heavenly bodies almost within hailing distance. The building was constructed of fiber wall board nailed to a framework on a concrete foundation. The construction of the dome was simplified by the use of this material, as the fiber boards, cut into sections, could be bent and fastened to the rounded framework of the roof. Millard is a musician whose hobby is astronomy. Makes Coats You Can Wear Either Side Out LONDON tailor has invented a re- versible coat that can be worn right- side-out or inside-out. After two years of experiment, he discovered a means of constructing the garment so it has the appearance of a well-tailored coat which- ever side is exposed. In a demonstration recently, he pulled on a smart, double-breasted blue nap overcoat. Then, reversing it, he was clad in a well-cut gaberdine raincoat with a belt. He says he can make a twin gar- ment of a raincoat, a dinner jacket, a suit coat, or an overcoat. other pages appear such diverse things as a new oil locomotive, the latest golf bag, big game hunting by mo- tercycle, a huge water-power plant, and many others. Un- usual inventions, new wonders of research, extraordinary peo- ple, amazing adventures—all these pass before your eyes each month in POPULAR SCIENCE MONTHLY. Hun- dreds of fascinating articles and illustrations provide en- tertainment, and keep you in step with scientific progress. | N THIS page are pictured | two cliff homes. On | POPULAR SCIENCE MONTHLY 57 Curious Apartment House Built by Nature HE wind was the ‘architect of a strange apartment dwelling for members of a semisavage tribe in East Turkestan. Under the high col- umns and domes of a wind-eroded cliff of solid stone in the in- terior of this wild, infrequently-visited country, lying in Cen- tral Asia between In- dia and Mongolia, the tribesmen have hol- lowed out ‘“‘apart- ments,”’ most of them consisting of but a single room. The holes in the base of the cliff in the picture are the doorways leading into these rooms. Our Best Snake Stories Are Wrong, Says Expert ANY of the popular beliefs about snakes are wrong, according to Karl P. Schmidt, assistant curator in charge of reptiles at the Field Museum, Chicago. The belief that counting the rattles of a rattlesnake will tell its age is rarely substantiated by fact, he declares. Equally erroneous are the ideas that a rattlesnake will not cross a_ horsehair rope nor a chalkline;. that it lives at peace with prairie dogs, and that it is possible to be poisoned by contact with an old broken fang from a rattler. Alcohol, instead of curing a snake bite, he says, be- comes an active aid to the poison. The reason people who take whisky for snake bites often recover, he de- clares, is because most snakes are not poisonous and frequently people ima- gine they have been poi- soned when they have not. Other widely-believed “snake stories” which he disposes of are the tales about “hoop snakes” that take their tails in their mouths and roll like hoops; “blow snakes” that poison with a blast of their veno- mous breath; ‘‘glass snakes” that break into pieces when struck with a stick; and “milk snakes” that suck milk from cows. Its Front Door Is a Tunnel A QUEER “cliff swallow L\ dwelling” has been built at Rottingdean, near Brighton, on the southern coast of England, by a sea captain. Thirty-five feet below the floor of the main building a doorway leads into the face of the sea The towering domes of these huge cliff dwellings of tribesmen in East Turkestan were carved from the rocks by the winds of centuries. cliff, connecting with a tunnel and stair- ways that rise to the house above. This permits an entrance and exit directly from and to the ocean beach. The design of the building itself is unique. The center of the roof is in the shape of a dome. In its general plan, the house suggests a vessel with one side to the sea. Some of the windows, as can be seen from the illustration below, are designed to resemble portholes; and the . decorations of the dwelling are similar to those on a ship. Large windows, facing the water, afford a clear view of the sea, so the out- look of one sitting inside the structure gives the impression of being on the upper deck of a steamship. The queer cliff dwelling of a British sea captain on the south coast of England. The “front door’’ at the base of the cliff leads to a tunnel connecting with a stairway to the house 35 feet above.

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Bus Runs on Extra Wheel If a Tire Goes Flat HEN a front tire blows out on a new type motor coach, recently demonstrated in Los Angeles, Calif., the passengers are guarded from accident by a solid steel auxiliary wheel attached to the axle behind the main wheel. There are two of these emergency wheels, one on each side. They are fitted with solid rubber tires and are two inches smaller in diameter than the main ones. Thus they touch the road only in the event of a blow-out or puncture, when the smaller wheel holds the deflated tire from the ground sufficiently to pre- vent rim cutting while the heavy coach is being brought to a stop. Advocates Prohibition of Teeth-Decaying Food F DR. JOHN P. BUCKLEY, a den- tist of Hollywood, Calif., has his way, a new amendment to the Constitution will prohibit eating foods that decay teeth. At a recent meeting of the Chi- cago Dental Society, he declared that the diet should be limited to rough foods which stimulate the gums and supply needed vitamins to the blood. At the same meeting, Dr. E. E. Dalton, of Chicago, estimated that Chicagoans wear $10,000,000 worth of gold teeth, and that $15,000,000 in gold teeth is buried annually in the United States. Bullfrog Army to Fight Alaskan Mosquitoes ULLFROGS from Oregon are going to the aid of Alaska in their fight against mosquitoes. Alaska has been a mosquito paradise because the country has contained no frogs, it is said. The vi- cious stinging of the insects caused misery to many “sourdoughs” in the early days, and still bothers inhabitants in summer. The large web-footed Oregon frogs are green and brown in color. They have gained wide fame as the natural enemy of the mosquito. An army of the croaking POPULAR SCIENCE MONTHLY insect fighters will be let loose in one of the Aleutian Islands by J. H. Wagner, Super- intendent of the Alaska division of the U. S. Bureau of Education. If they clean up the pests there, others will be put to work on the mainland. Auto Engine Loses Power in Damp Weather OES an automobile engine give more power in dry or damp weather? Many motorists are under the impression that the motor works best when the at- mosphere is humid. Recent laboratory tests, however, showed that power de- creases as humidity increases. When the humidity is high, the combustion rate is slowed up, resulting in apparently smoother engine operation. To obtain the most power available under humid conditions, says A. W. Gar- diner, of the General Motors Research Laboratories, who made the test, the spark should be advanced considerably. Max, gy Astronomers Say the Mom Is Brown; Mars Green IHE moon is not white, it js ‘te is not red, it is green! brow, These are the latest suggestions astronomers. A committee of the (. negie Institution, in Washington, D ( reports that the apparent silvery whit, ness of moonlight is due to contrast wij the darkened sky. The actual color y moon, or 4 believe, is the dull of weathered rocks. This su the surface of the satellite a be been weathered by oxidation, at previous time, although the moon j known to have no atmosphere now, Mars, according to E. J. Gounod, 4 the Amateur Astronomers Association 4 New York City, may be covered yij green vegetation like the earth. reason it appears red, he says, is that th light rays have to pass through the gy. mospheres of both Mars and the ear before they reach our eyes. These atma pheres filter out the blue and greg rays but allow the red rays to pay The three reasons most often giya for the red color of Mars are that th planet is “rusty” with iron rug that its soil and rocks are red, that it has red vegetation. *Skinny’’ Men Smartest, College Tests Show O THIN men have the mao brains? Recent investigations at Lafay. ette College, Easton, Pa., seem ty answer “yes.” It was found that those who were underweight stool higher in their studies than thos who were normal or overweight The study was made under super vision of Professor H. E. Brow, Director of Physical Education. The seven hundred students wh were tested were divided into thre groups—underweight, normal, ani overweight. When their school re. ords were examined, it was found Africa Hunter Brings ’Em Home on Motorcycle MACHINE that can outrun beasts of the jungle is adding a new thrill to big game hunting in Africa. Donald Ker, an Englishman living at Gilku, in Northern Nigeria, re- cently introduced the motorcycle as a mount for his hunting trips in the Sudan. Already he has bagged seven leopards by use of his speedy machine. Each time, after the big jungle cat was shot, he lifted it across the handlebars of his motorcycie and drove it in to Gilku. The motorcycle can follow paths and trails that would be impassable for an automobile, Ker explains, so it is an ideal mount for African hunt- ers who need a combination of speed and the ability to get off the traveled roads. By invading the jungles with his motorcycle, Ker has been able to cut traveling time considerably and get away on week-end hunting trips. the superiority in the standing d underweight men over the normal mei was about the same as that of the norml men above the overweight men. Lock for Emergency Brake to Prevent Runaways NEW type of automobile lock ha been designed to prevent thieve from towing away the machine and ts guarantee that the car will not run away when it is parked on a hillside. It locks the emergency brake lever so the brakes cannot be released until the owner re turns. Turning the key in the lock after the emergency lever has been pulled back operates a ratchet which pushes a rod down intoa hole in a special quadrant. This holds the lever in position un the key is turned again, lifting the rod. The device is & cially designed t old a heavy truck on a down g Emergency brake lock. Turning key inserts plunger into a hole in a quadrant below. May;

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an tho erweight, er super. _ Brown, tion. ents who ito three nal, and hool ree. is found nding d nal me e normal May, 1929 Artist Weaves Portraits ‘from’ Human Hair Hes: hair is the “paint” used by G. Boruchoff, a Russian artist, to form pictures which, at a first glance, are said to be indistinguishable from oil paint- ings. When he was ten years old, Boru- choff was apprenticed to a hairdresser and continued in this work for twenty- two years. During that time he had the idea of making hair pictures and made several attempts with small success. While a war prisoner in Germany, he spent his leisure in practice, and after the war began exhibiting his pictures which, in recent years, have aroused much in- erest.in Europe. ey he ole, he blends the various shades of hair together on his palette, as an oil painter mixes colors. His canvas is a piece of silk or linen cloth. His brush is a fine knitting needle. He knits the strands of hair to the cloth by a method which, he explains, is similar to that used in making the famous Gobelin tapestries. Boruchoff has expressed fear that the bobbed hair fashion may kill his art, as he needs long strands for his work. A Substitute for the Bulky Golf Bag AVOID the trouble of bending over to pick up a golf club bag and of pulling a club from its interior, E. R. Barany, a Madison, Wis., golfer, has designed a new coverless carrying rack which stands like an easel, hold- ing the clubs in a row like billiard cues. While the rack is being carried, the clubs are locked in place, each in a separate compartment, by a hinged bar that holds them with rubber cleats. When the player is ready to choose a club for the next shot, this bar is released by pressing a button operating the locking catch. Only a fifth of the usual time is needed to select a club with his device, the inventor claims. The stand is carried by a rubber grip on the side of the frame. When it is placed on the ground, a light metal sup- port swings out to hold it in a slightly ; 4.) Made of light metal, the club rack stands on its Own legs. Note the grip at side of frame. POPULAR SCIENCE MONTHLY 59 inclined position. The material of which the device is con- structed, says the inventor, is a composition combining great strength with extreme light- ness. Seven clubs and four golf balls fit into the rack. Golf Club Picks Up the Ball RUBBER suction cup at- tached to the top of the putter handle is designed to do away with the bother of stooping to pick up golf balls on the green. When this pick-up is pressed Talk to Byrd from Panama EN in _ furs, standing on the ice of the Antarctic, talked with men per- spiring under the tropical sun recently when communication was established be- tween members of the U.S. Army stationed in Panama and the Byrd _ expedition at the Bay of Whales. The words sped from Balboa, Panama, to down over the ball, it fits snugly around it, holding it fast. The cup can be removed easily if it is in the way when the club is in use. Rubber-Band Luggage Rack Does Double Duty FLEXIBLE luggage carrier for auto- mobile running boards serves the double purpose of holding luggage and, when not in use, of protecting the paint above the running board from being scuffed by persons entering the machine. It consists of a wide band of rubber attached to the body just above the run- ning board so that it can be stretched out to hold packages and luggage during a trip. When the luggage is removed, it snaps back in place. Because of its resiliency, the maker says, it holds the luggage securely and prevents bouncing. The holders are manufactured in a variety of colors to match the shades of different cars. They’re Taking the Chill Out of Ice Cream F YOUR mouth aches after eating cold ice cream, you may soon be able to buy “‘warm”’ ice cream to suit your taste. A research chemist, G. D. Turnbow, formerly connected with the University of California, has invented a process of making ice cream at a high temperature. The confection produced by the Turn- bow process has smaller crystals and is made by rapid freezing. The product, demonstrated recently before a conven- tion of ice cream manufacturers in California, is expected to prove popular during winter months when the consump- tion of ice cream usually falls off. How a rubber suction cup on the club lifts the golf ball. the Antarctic wastes and back. The feat is considered a triumph for the new type of low-powered, portable short- wave set designed for the Army Signal Corps and used in the experiment. Three small storage batteries operate the trans- mitter of the portable set, which has been used to communicate with stations ™ a) up to 8,000 miles distant. Millions of Reptiles Killed for Leather 4 SUPPLY the demand for rep- tile leather for shoes, luggage, and hand bags, more than a million alligators, a million other lizards, and 800,000 snakes were killed last year. The alligators come chiefly from Mississippi, Louisiana, Florida, Mexico, Central America, Venezuela, and Madagascar. The Amazon River, ef South America, contains more alligators than any other stream in the world. Many of the lizards come from far-off Borneo aid Java, while the Dutch East Indies supply most of the python skins. : Few farms are maintained to raise reptiles for their skins. The growth of large snakes is too slow to make such a venture profitable. Before they are killed, the snakes must be from six to twenty feet long. The average age at which alligators are killed for their hides is estimated to be fifty years. Three Hundred Times as Sweet as Sugar | age perfumes, flavorings, and sweets are being extracted from common corncobs in the chemical laboratories of Iowa State College by Dr. Henry Gilman and A. P. Hewlett, organic chemists. A compound about 300 times as sweet as sugar, they report, has been created from the waste material. If tests prove it harm- less to the human system, it may become widely used for sweetening foods, espe- cially for diabetic patients. Other compounds may possibly be used for maple or walnut flavoring, or as an added flavoring for coffee. From the corncobs the chemists have also produced raisin, caraway, and apple flavors, as well as rare perfumes, one resembling champaca, a heavy, fragrant odor of the flowers of an East Indian tree. Still another product of these labora- tory workers is a local anesthetic, pre- pared from cobs, which is said to be approximately as effective as novocaine.

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« ee ee earl POPULAR SCIENCE MONTELY Curious “Log House” Built of Drainpipes A “LOG house,” in which the “logs” f£% are formed by common red drain- pipe tile, has been built in Kingsville, Ontario, Canada. Charles Miner, who erected the unique dwelling, chose tile for the material because it provides dead-air space in the walls to protect the interior from cold in winter and heat in summer. The house stands on a foundation of cement blocks, except for the porch and steps, which are supported by the tiles. A. wooden framework, sheathed with boards in the usual manner, was first erected and the tile “logs” were laid in courses like brick veneer up the sides. At corners, the ends of the tiles overlap in criss-cross fashion, much as did logs in the cabins of pioneer days. Where the ends of the tiles are exposed, they are closed with cement colored to match. This insures dead-air space and prevents birds and squirrels from entering. The cost of the unusual house is said to have been moderate as compared with the cost of constructing a conventional type wood or brick home. Trees Worth Millions HAT is a tree worth? In answer to that question, Dr. Ephraim P. Felt, former New York State entomologist, re- ports that fifty fair-sized elms were sold recently at $5,000 apiece and that many trees are worth $10,000. He estimates that the trees of Greenwich, Connecti- cut, for which the town is noted, are worth at least one fourth the assessed value of the town. This would place the total value of the trees at approximately $25,000,000. Do You Know a “‘Decibel?’’ It’s a New Unit HEN you hear someone speaking of a “decibel,” it is not a man with a cold in his head talking about a decimal. It is a telephone engineer using the latest addition to the list of scientific units. At a recent conference between repre- The house with drainpipe walls. Left: Corner of dwelling, showing ‘‘log cabin’’ method of joining. sentatives of the Bell System and the In- ternational Advisory Committee on Long Distance Telephony in Europe, the new term, referring to the efficiency of tele- phone circuits, was adopted. It takes the place of the former expression “transmis- sion unit.” The original unit name decided upon was “bel,” named in honor of Alexander Graham Bell, inventor of the telephone. Because the “bel” is larger than is needed in practice, a unit one tenth as large, called a decibel, was accepted for practical use by the engineers. Helps You Pick a Cinder . Out of Your Eye SAFETY-FIRST device, small enough to carry in a vest pocket, has been invented by A. F. Ouellet, of New York City, to aid in removing cinders or dust particles from your eyes. A five-power magnifying mirror, one inch in diameter, is fitted with a wire clamp by which it is attached to the little finger of the left hand. While the mirror is held before the irritated eye, the thumb and forefinger of the same hand push back the eyelids, and a folded piece of soft paper, cut to a point, is manipulated by the right hand to remove the dust speck. The eye that is being treated observes the action. Besides magnifying the eye, the mirror reflects light on the spot where the irri- tating particle is located: The mirror and clamp fit into a small case for carrying in a man’s pocket or in a woman’s hand bag. Mirror is clamped to little finger of left hand while the right hand fishes for cinder. May, 1939 ==. A Pattern of Progress | Ace month scores of achievements in many fields of research and inyen. tion go to make up the varie. | gated pattern of scientific | progress. POPULAR SCIENCE | MONTHLY reports the news of | these achievements in under. © standable stories and pictures, In these pages you will find a wealth of fascinating new facts to widen your knowl edge, ingenious ideas that can be put to use, and enter. © taining glimpses that will keep you in touch with what other ~ men are doing. Dual Control for Piano Stops Pupil’s Mistakes LEASANT news for sensitive-eared parents, to whom the hours when the teacher comes and tries to teach Junior and Mary to coax music from a piano mean sheer agony, emanated the other day from Germany. There an inventor has perfected a device whereby the music teacher may correct the piano pupil's mistakes even before they happen! The contrivance consists principally of a keyboard like that of a piano. Through electrical impulses sent by way of conneet- ing wires, the teacher can control the in- terior workings of his pupil’s piano from his silent keyboard. The invention is an adaptation of the principle of dual controls used to instruct students of aviation. Lights Rout Two Enemies of Fruits and Plants ANGING festoons of electric lights on apple trees, as is done on Christ- mas trees, is an effective way of keeping aphids, or plant lice, out of orchards, Prof. A. Franklin Shull, of the University of Michigan, reported recently. Some of the aphids grow wings and fly away from the trees on which they are born; others are wingless and remain to destroy the budding fruit. Dr. Shull discovered that the wingless aphids have not been ex- posed to sufficient light, but will grow wings if properly illuminated. The tobacco farmer’s most dreaded pest, “mosaic disease,’ which ruins the leaf for market by forming a mosaic pat- tern upon it, can be killed by less than fifteen seconds’ exposure to ultra-violet rays from a quartz mercury vapor arc, Dr. John M. Archer, of Boyce Thompson Institute for Plant Research, says. Produces Shapely Pickles pre epee ED pickles that will appeal to the eye as well as the appe- tite are being sought, according to a re- cent announcement of the Pickle Packers Association. Professor George E. Starr, of the University of Michigan, has spent five years experimenting with cucumbers to evolve new shapes that would combine beauty and edibility, the report states. The result jis said to answer both re- quirements, and the latest model of. pickles will soon be put on the market. May A ~ A) of rig str

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POPULAR SCIENCE MONTHLY Church in a Day May, 1929 Amateur Carpenters Build ve-eared ‘hen the 1 Junior & piano ie other nventor ie music pupil's n! pally of ‘hrough onnect- the in- no from . of the nstruct mies Ss lights Christ- eeping -hards, versity ome of y from others »y the d that on ex- grow eaded is the c pat- | than violet r arc, npson les will appe- a re- ckers starr, spent ibers ibine es. h re- 1 of at. A group of Milwaukee preacher-carpenters trying their skill with saws, levels, and hammers. REACHERS turnedcarpenters and churchgoers became builders _re- cently in Milwaukee, Wis., when the new Roosevelt Drive Presby- terian Church was erected in one day. Operations began at eight o'clock in the morning and by five that afternoon the building was complete, with electric wir- ing installed, chimneys and foundation solidly in position, and with even a small tower rising above the roof of the struc- ture. Painting and decorating the church was practically finished before dark. All Presbyterian ministers in the Wis- consin city were drafted to help with the construction. Shortly before eight they began appearing, with members of their congregations, carrying saws and ham- mers. They wore a wide variety of garb, ranging from well-pressed black overcoats and kid gloves to sweaters and work- man’s mittens. To withstand the cold wind blowing from Lake Michigan, one minister appeared with heavy laced boots, a leather jacket, and an aviator’s helmet. Forty minutes after work began, the skeleton of the structure was up and the wall boards began to go in place. Before noon, part of the roof was on and painters were giving the exterior its first coat of paint, electricians were laying cables, and plumbers were installing pipes. A building contractor, who is a member of one of the churches, bossed the job and saw that the joists and beams went in the right place and that the scaffolds were strong enough to hold the workers. Cave Children Had Rickets ABY dinosaurs and children of cave men had the rickets, just as children of today who have insufficient sun- light and improper diet are afflicted with the disease. Dr. John Foote, Professor of Children’s Diseases at Georgetown University, Washington, D. C., states this after a study of pre- historic paintings and the remains of extinct races and animals. Egyptian mummies, as well as the bones of early American Indians, show the effect of rickets, he says, and often in primitive religious paintings, the artists uncon- sciously depicted the effects of the disease. Parlor Baseball Played with Tiddledywinks OU can make “hits,’’ “runs,” and “fouls,” with a new table baseball game based on the old pastime of “‘tid- dledywinks.” A diamond, laid out on a board about two square feet in area, is divided into zones. Small celluloid disks representing batted balls are snapped with a larger disk from home plate. They score “base hits,” “home runs” or ‘fouls,’ according to the zones in which they land. A player is “out” when a disk comes to rest within or touching the line indicating any fielder’s position. Each player has nine small disks, repre- senting the members of a baseball team. He “bats” until he has three outs, and the one who has the highest score at the end of nine innings of play is the winner. Skill in snapping the tiddledywink ‘‘ball players’’ into de- sired zones of the field decides the winner of the novel game. Can he hit it? Rev. Thomas B. Lyter, Milwaukee pastor, start- ing a nail in the construction of a wall section of the church. Left: The building nearing completion toward the end of the day’s work. It even Finds Tracing Cloth Acts Like ‘‘Health Glass”’ ISCOVERY of acheap way of getting ultra-violet rays, which will allow everyone to take sun baths in his own home, is claimed by C. H. Young, of McGill University, Montreal, Canada. Ordinary tracing cloth, such as is used by draftsmen, admits the beneficial rays which are stopped by paper and ordinary cloth, he reports. Besides allowing the health rays to pass, the tracing cloth filters off other rays, reducing much of the heat, Young discovered. A single thickness of tracing cloth between wide-meshed wire screens will form a curtain that will allow the ultra-violet light to enter the room, at the same time eliminating much of the heat of the sun, as well as glare. While sitting be- fore such a curtain, however, the eyes should be protected by smoked goggles in the same manner as during treatments with so-called “‘health lamps.” 682,308 Bird Immigrants THOUSAND canaries a day came to the United States last year, says a report of the U. S. Department of Agri- culture. This average is the highest yet attained. Of the 682,308 feath- ered immigrants of 1928, half a mil- lion were these cheerful yellow song birds. Parrots ranked next, number- ing 56,307. They came chiefly from Australia and tropical America. As very few parrots breed in captivity in the United States, their number must be constantly replenished. Of the game birds imported, nearly two thirds were Mexican quail.

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ee ee Bitchine , honograph to Radio How to Connect an Electrical Pick-Up That Will Switch You from Broadcast to Recorded Programs, as You Please Fig. 1. One method of wiring electrical pick-up to audio amplifier of radio receiver. O MATTER how you twirl the dials on your radio set, you ‘often find that you can’t get dance music just when your guests feel in the mood for dancing. And at other times, when you want soothing music, the air frequently seems filled with an uninteresting hash of jazz and thinly disguised advertising. Furthermore, there are times, particularly during the summer, when the static is so bad that it | spoils radio reception except, per- | haps, from the nearest local station. However, there is an easy and simple way to get the kind of music POPULAR SCIENCE MONTHLY By ALFRED P. LANE scientific details to obtain an adequate understanding of the electrical phonograph pick-up. The radio signal reaching your antenna is a high-frequency electrical oscillation. In other words, the current is traveling first in one direction and then the other and changes direction between 550,000 and 1,500,000 times a second, depending on what station you are receiving. May, 199 box vibrate in time with the waves in the groove. The dia- phragm transmits its vibrations to the air and these vibra- tions reach your ear by way of the horn. Thus the phono- graph converts the vibrations produced in the needle di- rectly into PERMANENT MAGNET . dal article shows you how to use either the audio amplifier in your radio receiver or a separate high-power amplifier to repro- duce modern phonograph rec- ords. You should have no trouble following the directions for con- necting an electrical pick-up. However, if your own case pre- sents special problems or diffi- culties, explain your troubles in detail, preferably with diagrams, in a letter to the Technical Editor, POPULAR SCIENCE MONTHLY. | sound waves by PO ee ; mechanical a typical balenailil | means. In the mature type pick-up, | electrical phonograph pick-up the needle yj. | brations are converted into equiva. lent electrical vibrations. These | are amplified through the audio | amplifying stages of your radio | receiver and reproduced as sound | through the radio loudspeaker. Figure 3 is a diagrammatic repre. sentation of a typical balanced armature type of electrical phono- graph pick-up. A strong perma. nent magnet is fitted with double pole pieces, between which is mounted a coil of fine wire. The armature of iron is pivoted between these pole pieces. A socket anda you want when you want it. An electrical pick-up and a phonograph turntable operated in connection with your radio receiver will enable you to listen to radio programs when they please you, and the rest of the time to manu- facture your own musical program from a. selection of phonograph records. Most radio fans know in a general way how the radio impulses conveyed to the radio receiver by the antenna result in understandable sounds coming from the loudspeaker. The process is almost un- believably intricate if you dig down into the real scientific whys and wherefores. But you don’t have to master all these TO Sheersc AUDIO AMPLIFIER Fig. 2. Control system for eliminating needle scratch, giving a choice of three condensers. As the human ear cannot hear a sound vibration much beyond 30,000 waves a second, you could not hear the radio wave even if it were converted into an air vibration. Moreover, the radio im- pulse is extremely weak, so three things must be done to it before you can hear it. One is to make it much stronger. An- other is to convert it into a frequency that will register on the human ear. And then, when that has been accomplished, the sound wave must be multiplied many times in order to attain loudspeaker strength. The first of these jobs is performed by the tubes marked “RF” or “Radio Frequency” in your receiver. The second is done by the detector tube. Then the audible signal coming from the detector tube is raised to loudspeaker strength by the audio amplifier stages in your set. Most everybody knows how an ordi- nary phonograph works. The needle follows the wavy groove in the record and makes the diaphragm of the sound Fig. 4. Another method of wiring to the audio ampli- fier, by the use of a plug and jack instead of switch. set screw for a regular phonograph needle is provided in one end of the arma- ture. Usually the space between the armature and the pole pieces is packed with live rubber to prevent unwanted motion. That’s all there is to it, and its opera tion is equally simple. As the needle moves back and forth in following the wavy groove in the phonograph record, it changes the strength of the magnetic field between the pole pieces and conse quently changes the field in which the coil is located. These changes in the magnetic field generate in the windings

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ad ddddddddduadidddda N N «NEEDLE truction of lanced ar. = pick-up, eedle vi. equiva. These e audio ir radio S sound aker, ic repre. alanced phono. perma- double hich is e. The ret ween t and a is graph arma- n the packed ranted opera- g the ecord, gnetie -onse- h the n the Fig. 5. Mounting of electric drive turntable. The turntable itself is omitted to show the motor. corresponding electric currents. These currents are strong enough to give satis- factory reproduction of the phonograph record in a pair of ordinary headphones attached directly to the winding in the electrical pick-up. The volume is roughly equivalent to the strength of signal you get out of headphones hooked in the detector circuit of a radio receiver. Now, to obtain loudspeaker vol- ume, the process is exactly the same as in amplifying the signal from the detector tube in the radio set. An audio amplifier is needed in either ease. Your radio receiver contains such an amplifier. Figs. 1 and 4 show two ways to do a permanent wiring job that will permit you to use the audio amplifier in your radio receiver to amplify the output of an electrical pick-up. Both methods allow you to shift instantly from radio reproduc- tion to phonograph music and vice versa, simply by throwing a switch or pulling a plug, and without dis- turbing the tubes in the radio re- ceiver. HE switch A in Fig. 1 may be either a plain, porcelain base, double-pole, double-throw battery switch, or a panel-mounting jack switch of the same type. The audio transformer shown at the right rep- resents the first stage audio trans- former in your radio receiver. If the terminals of the transformer in your set are not marked, you can identify the P terminal by checking the wiring. The P terminal of the transformer always is connected to the P terminal of the detector socket either directly, through the tickler coil, or by way of a radio- frequency choke coil. The wires X and Y are the wires which, in your receiver, were attached to the P and B binding posts of the audio trans- former, the X wire going to the P ter- minal and the Y wire to the B terminal. Fig. 4 is essentially the same except that a double-circuit jack is used instead of a double-pole, double-throw switch. N FIG. 1, when the switch A is thrown to the up position, the electrical phonograph pick-up is connected to the primary winding of the first stage audio transformer. In the down position, the circuit is restored to its original condi- tion so that the weak audio signals from the detector tube are applied to the wind- ing of the transformer. In Fig. 4, when the plug to which the electrical pick-up 1s attached is inserted in the jack, the pick-up is connected to the transformer and when the plug is withdrawn, the cir- cuit is restored for radio reception. POPULAR SCIENCE MONTHLY The volume control, when you are reproducing phonograph records elec- trically, usually is accomplished by the aid of a potentiometer such as R in Fig. 1. The value of this potentiom- eter may be anywhere from 10,000 to 50,000 ohms. The potentiometer R and a fixed condenser C usually are mounted in the control box that is part of the complete electrical pick- up equipment as supplied by the dealer. The function of the condenser is to by-pass the very high frequencies and thus greatly reduce the scratching noise produced by the needle. Some of the higher overtones of the music are reduced thereby, but the net result is improved. If you want to arrange to cut even more of the needle scratch you can wire a control system as shown in Fig. 2, where the fixed condenser supplied with the outfit is supplemented by any one of Fig. 6. Complete assembly of powerful audio amplifier, radio receiver, electric turntable, and electrical phonograph pick-up. three additional condensers at the choice of the operator. f One of the features of home assembled radio and phonographic reproducing ap- paratus is the wide latitude possible in fitting the equipment into existing cabi- nets or other available space. Fig. 6 shows one method of assem- bling a powerful audio amplifier, a radio receiver, an electric turntable, and an electric pick-up in a cabinet ordinarily designed to house a battery set, the bat- teries, and a built-in horn loudspeaker. In the lower compartment is installed the super-power audio amplifier described in detail in the March number of PopuLar Scrence Monruaty. In the middle com- partment is a radio receiver consisting only of the radio-frequency amplifier and detector circuits. The top compartment is fitted with a separate pair of inner doors. The phonograph unit is installed between partitions in the center of the compartment, leaving space in side com- partments to accommodate several] pho- nograph record albums. The use of an electric drive turntable has nothing to do with the electrical reproduction of the phonograph records. 63 The pick-up will work just as well if the turntable is turned by the power of a spring wound by hand, so if you have an old phonograph, you can, of course, mount the pick-up in place of the old tone arm and use an extension cord to reach the cabinet where the audio amplifier is ‘ housed. - Similarly, you can mount the electric drive turntable and the pick-up in some other cabinet or even in a con- venient bookcase if the radio cabinet is not large enough to include it. , pe mounting of an electric drive turntable such as is shown in Fig. 5 is very simple. In this view the turntable itself was left off to show the motor more clearly. The turntable fits over the cen- ter pin and is driven by friction so that there will be no chance of stripping the fully inclosed worm gearing. A special type of motor that has no brushes is used, so that it cannot create elec- trical interference. It operates, of course, on the 110-volt A.C. supply from the light wires. The mounting consists simply of an open box turned upside down with an opening cut in the bottom, into which the motor drive can be set. The outside measurements of the box are five by twelve and a half by fifteen inches. A control panel is fitted to one side and holds switches to control the change from radio to phonograph, to start and stop the phonograph table motor, and to control the volume. The high-grade dynamic speaker mounted on a baffle board, which was described in the April number of PopuLtarR Scrence MonrHa_y, is ideal for use with such an outfit. E jack switch A shown in Fig. 1 is at the extreme right on the panel of the phonograph unit pic- tured in Fig. 7. The P and B wires . go to the binding posts on the super- power amplifier marked “Input,” the Y wire goes to the 0 to 90 volt binding post, and the X wire con- nects with the P terminal of the de- tector tube socket in the radio receiver. The knob on the panel in Fig. 7 con- trols phonograph volume. Wiring is shown in Fig. 1. The switch at the ex- treme left of the panel in Fig. 7 is a single- pole double-throw switch that turns off the filament-heating transformer in the radio receiver and turns on the current to the phonograph motor when you wish to play records. The remaining switch is wired into the phonograph motor circuit to stop it while you change records. Fig. 7. The electric turntable on its simple mounting, showing control panel with switches.

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POPULAR SCIENCE MONTHLY May, 1099 Useful Hints for the Radio Fans Trouble-Shooting with Phones How to Test Transformers or Other Parts of Your Set with a C-Battery and “EKarmuffs”—Tips on Regeneration ITH a pair of headphones and a dry cell C-battery, you can track down many of the troubles you may have with your radio receiving equipment. Of course an ordinary doorbell battery would serve just as well, but the C-battery is handy because it is small. And if you know how to use them, the headphones alone will locate many trou- bles or at least determine the section of the receiver that requires attention. In your receiver, the electric currents travel in definite paths. When a break occurs in one of these paths reception stops or is greatly impaired. Complete stoppage follows any break in the filament wiring, but a break in any of the high- frequency circuits may not absolutely stop the signals from getting through. High-frequency currents are able to jump breaks, to some extent, by way of the electrical capacity of the adjacent wires. Suppose, for instance, that you can find nothing wrong with any connections, yet the set is dead, with no sound from the loudspeaker. Connect the headphone cord tips in place of the P and B ter- minals of the first audio transformer. If you hear the broadcasting you may be sure that whatever trouble exists is in * the audio amplifier end of the set and not in the radio-frequency or detector stages. Shift the cord tips to take the place of the P and B terminals of the second audio transformer. If the signals are heard much louder, you can forget about the first audio stage and concen- trate on finding out what’s wrong with the last audio stage. Then, if one of the audio transformers is suspected, just hook one phone cord tip to a terminal on the C-battery, con- nect the other terminal of the battery to one primary terminal of the audio trans- former, and touch the remaining cord tip to the other primary terminal of the transformer. If you hear a good, snappy click when the contact is made and another when it is broken, you can be - sure nothing is the matter with the wind- ing. After that you can test the secondary winding in the same manner. If the click is extremely faint or in- audible the wire of the winding is broken at some point. AD10-frequency choke coils, tuning coils, resistances—even grid leaks— can be tested in the same way. If you sus- pect that the plates of a variable condenser are touching at some point on the dial, you can connect condenser in series with the headphones and the C-battery and turn the rotary plates. If the latter touch A sharp click in phones says the windings are all right. Testing audio transformer. the stationary plates at any point there will be a tremendous clatter in the head- phones. To find out if a fixed condenser is short- circuited, connect the cord tips to the terminals of the condenser and connect one terminal of the battery to one ter- | | A B C’s of Radio HE grid in a radio vacuum tube is the electrode that controls the tube’s action. The electron flow from the | heated filament must pass through the grid to reach the | plate and thus cause current | to flow in the plate circuit. In a radio-frequency ampli- fier circuit the grid is connected to the radio-frequency trans- former, and in an audio-fre- quency amplifying circuit to one end of the secondary wind- ing of the audio transformer. In either case the voltage de- veloped in the transformer is applied to the grid. The chang- ing voltage of the grid causes a | corresponding change in the flow of the electrons and con- sequently in the plate current which actuates the transform- er of the next stage following, or the loudspeaker in the case of the last tube. | | | | | minal of the condenser. Then snap 4 wire from the other terminal of the bat. tery across the other terminal of the co: denser. If the condenser is completely short-circuited, there will be practically no click in the phones. Regeneration and Quality ADIO receivers vary considerably ag to their sensitiveness at different wave lengths. Many are extremely sensi. tive on the lower end of the broadcast band and much less sensitive when tuned to any wave in the upper portion of the band. That is why static usually seems much worse on the low waves. The static really is no worse in most cases. It merely sounds louder because the set is more sensitive at that point. This also accounts for the fact that you often can get a relatively low-powered station near the lower numbers on the dial with good volume when a much more powerful station tuning-in near the other end of the dial cannot be heard at all. Sometimes the condition is reversed in sets using the grid resistance method of suppressing oscillation, because the effect of the grid resistances is much greater on the low waves. In any set, maximum sen- sitiveness and selectivity will be obtained when the radio-frequency stages are on the verge of oscillation. Unfortunately, however, tone quality always suffers when oscillation, otherwise known as re generation, is excessive. In designing a radio receiver, the en- gineer always strives to have just enough regeneration in the circuit to give best results without unduly affecting toné quality. And if he can accomplish this result with not too great a difference it sensitiveness at various points on the dial, the receiver will be a success— assuming, of course, that it is fitted with an audio amplifier that gives the desired volume without distortion. The Right Grid Leak O TWO vacuum tubes require ex the same value of grid leak for max- mum results, but in any case the higher the resistance of the grid leak the greatet will be the sensitiveness of the tubé to weak or distant signals and greater will be the tendency toward dit tortion on the local stations. The rulé therefore, is to use a grid leak of f two to five megohms when you are hunt ing distant stations, and a leak of as low as one half megohm if you are princi interested in obtaining the best possible tone quality. . May, 19 “9 AS real dist program with sor of ’em. | stations casting phonogr pan, squ for varie soprano: I got ’e all hash is the m My ne Those o the bea’ stations But | dealer vy complet casting hundred agree th can be « without Some stations “clearec

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‘Dp 4 sa25se8 we | 25° 4.9. as |. Fs e-5 2Gees r= aT SSP Se. 8.2 eS May, 1929 ud rad ben 2 >birakhm2en oe 4 POPULAR SCIENCE MONTHLY If you ever get the radio stations in bunches, all hashed together, this ar- ticle will be of much interest to you. Unscrambling the Radio Hash When “‘Squealing Pigs” Get Mixed with “Dishpans” and Sour Sopranos, Don’t Blame Your Set — Tell It to Uncle Sam “ AST night,” one of my neighbors told me, “I took a notion to doa little radio exploring and what do you think I dragged in?” I smiled in anticipation, for this man is good at stringing the long bow. ““Now you're going to tell me,” I countered, “that you got Japan or Australia.” “Oh, no. Nothing like that,’’ he said. “TI wasn’t spraining my set trying to get real distance. Just didn’t like the local programs so I set out to find a station with something different. And I got lots of ’em. Only trouble was that most of the stations sounded as if they were broad- casting bands made up of tinny old phonographs, somebody slugging a dish- pan, squealing pigs, and steam whistles for variety. The rest were spouting sour sopranos. Near the bottom of the dial I got ’em in bunches like bananas, but all hashed together. What in blue blazes is the matter with my set?” My neighbor's experience is not unique. Those of you who have ventured out of the beaten radio paths leading to local stations have had similar difficulties. But before you go gunning for the dealer who sold you the set, look at a complete list of the stations now broad- casting in the United States. There are hundreds, yet competent radio engineers agree that only about ninety-five stations can be crowded into the broadcast band without possibility of interference. Some of the larger and more popular stations operate on what are called “cleared” channels. Each has a wave By JOHN CARR for its exclusive use. Theoretically, at least, you should receive such stations without interference. Actually that is not always the case. Reception from WJZ in New York, for instance, often is marred by a high-pitched whistle caused by heterodyning with the wave from some other station off its own wave or so heavily modulated that it slops over outside its own band. Don’t blame your set for whistles of this nature. You couldn’t get rid of them with any set. However, reception such as my neighbor reported is found on the lower portion of the wave band where many relatively low power stations in different parts of the country operate at the same time on the same wave. In theory, the range of these small stations is so limited that they cannot interfere. But on any night favorable for trans- mission, any one of them may shoot its carrier wave thousands of miles and mess up the reception from other stations on the same wave. Here, too, your set isn’t to blame, nor is there anything you can do about it except to tune away from the interfering stations. Like many others, you have been led to believe, perhaps, that the new re- arrangement of stations would end all interference; and you have reasoned, quite logically, that any interference nec- essarily must be the fault of your set. Perhaps some day the Federal Radio Commission will get things straightened out so you won’t get two stations at once on any wave. The Commission has a difficult problem to solve, and you can help it by making reports of all inter- ference between stations. Simply give the technical facts such as the time of day, the call letters of the stations in- volved, the presence or absence of steady whistling noises, the length of your antenna, and the type of receiver. Fortunately, enough stations are operat- ing on cleared channels to assure that you can get at least one without interfer- ence. In favorable localities you may have a half dozen to choose from. EMEMBER, too, that while your own receiver may not be as selective as it might be, any material increase in selectivity would result in poorer tone quality. This is because an ultra-selec- tive set almost invariably chops the side bands from the radio wave you are re- ceiving. The side bands carry the higher audible frequencies. When they are lost the announcer’s voice becomes throaty and difficult to understand and the lost overtones spoil the music. However, radio reception costs but a few cents an hour at most. When we remember that for this trifling sum we can listen to the world’s finest singers, the most famous orchestras, word by word reports of important sporting events, and a host of other good things, there seems small ground for kicking at slight inconveniences.

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Drawing Water Power from Scotch Highlands LUNGING 600 feet down a moun- tainside through three huge pipe lines, tons of water from a highland lake in central Scotland will crash against the turbine wheels of an electric power plant now nearing completion in the valley below. The major link in this great water power project is a fifteen-foot tunnel bored for fifteen miles through the moun- tain, Ben Nevis. When the water reaches the lower end of this tunnel, it enters three pipe lines, each measuring five feet nine inches in diameter, for the drop to the power plant. The project, said to be the largest ever attempted in Scotland, is designed to supply electric current for a_ British aluminum company which is building a large factory at Fort Williams, a village near Ben Nevis. The photograph above, showing two of the huge pipes, gives an idea of the precipitous drop. Designs Great Telescope Mirror Like Honeycomb GGSHELLS, spider webs, and honey- combs were studied by Prof. George W. Ritchey, famous astronomer and de- signer of the 100-inch Hooker telescope at Mt. Wilson Observatory, California, in planning a new instrument unlike any telescope ever built before. These every- day objects were examined to compare the details of their cellular construction. His plan is to build a monster reflector, as large or larger than the 200-inch one planned by the California Institute of Technology, of pieces joined together like the cells of a honeycomb. This unique method of construction, Prof. Ritchey believes, will permit the building of telescopes larger than would be possible POPULAR SCIENCE MONTHLY by casting the mirrors as a single disk Another advantage of the “‘cellular’ construction, he points out, is that the small pieces that make up the large mir- rors can be transported up narrow trails to mountain observatories where it would be impossible to take the huge, fragile disks of single-piece mirrors. Professor Ritchey is working on the new reflector in this laboratory in Paris, where he was invited by the French after he designed the Hooker telescope several years ago. A dome of steel, concrete, and cork is contemplated for housing the new instru- ment. The cost of the telescope and observatory is estimated at from $10,- 000,000 to $15,000,000. ’ Fugitive Trapped by Long Distance Radio Photo IDING the ether for 2,600 miles, the radioed photograph of an escaped forgery suspect recently resulted in his identification and arrest in Honolulu when he disembarked from a vessel there after eluding New York detectives who had trailed him across the continent. After jumping bail in New York, the suspect started for the Orient. He was followed to San Francisco, where the detectives missed him by a day. A radio message to the captain'of the vessel re- sulted in determining that a man re- sembling the suspect was on board. Detectives sent his photo by radio to Honolulu, where the man was arrested when the ship docked. The cost of transmitting the picture was fifty dollars. May, 1999 Novel Stirrup Clamp Aids in Battery Repairs SIMPLE device to aid the man in removing the cells of a battery has been invented by R. Grice, a garage proprietor of Taunton, Mass. It is a slip-on clamp which around a battery, and is equipped With stirrups upon which the mechanic gs to hold the battery down while he pully out the cells. In reinsulating a battery all three cells can be removed at onee. The inventor claims the device will fit virtually every type of battery. Resting his weight on the stirrups, the mechanic easily lifts out the cells of the storage battery. Automatic Torch Cuts Steel Like a Jig Saw A NEW oxy-acetylene shape-cutting machine has been invented to cut intricate patterns out of heavy steel sheets, plates, and ingots almost as easily as shaping wood with a jig saw. The cutting torch is mounted on a car- riage which is moved in any direction by means of an electric motor. For quan- tity production, it is claimed the machine can be set to operate automatically. For special work, a special tracing device is attached which enables the operator to direct the torch along intricate lines and ae | curves of a pattern laid out on the steel, The speed of the cutting is from three to twenty inches a minute, according to the thickness of the metal. Tests are said to have shown that the melti heat of the torch will cut through materill a foot or more in thickness, producing straight corners and smooth faces that require little machining. Rigid construction of the machine's parts is combined with the delicacy of adjustment which is necessary for pre cision. Only one operator is required. Cutting out a pattern from a heavy sheet of steel with the new oxy-acetylene “‘jig-eaw’’ machine. The cutting torch is mounted on a carriage which is moved by an electric motor in any direction. |b pe cons Walker, ¢ organizat Md. Lac he said, I cruel, anc Drinki get the | a quart « added to would im Odd N Al adde boats by Wash. Miss La: The sp in wate

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May, 1929 Diet of Milk Makes Worms Alluring to Fishes F WORMS are fed on a diet of moss and milk they turn a delicate pink, which < creases their value as bait. This proc- . known as “scouring,” was recently ‘excribed in a report of the U. S. Depart- ment of Agriculture by W. R. Walton, said to be a distant relative of the patron saint of all anglers, Izaak Walton. The worms are placed in a container filled with moss. Sphagnum moss, found in damp woods throughout the northern states, is preferable. Three or four days of the moss diet prepares the worms for yse. If they are kept in the container for longer periods, the diet should include sweet milk once a week, and the moss should be washed every ten days. This unique diet is said to make the worms more lively, tougher, and more easy to handle. The skin becomes trans- rent. The delicate pink color, for some unknown reason, is alluring to many kinds of fish, especially game fish such as trout, Walton reports. More Lime, Fewer Divorces, Declares Dietitian VORCES would be fewer if people consumed more lime, Dr. George Walker, dietitian, recently told a national organization of housewives at Baltimore, Md. Lack of lime in the human system, he said, makes women nervous and men cruel, and disrupts family happiness. Drinking milk is the easiest method to get the needed lime, he declared, and a quart of milk a day and two oranges added to the diet of the average person would improve his temper. POPULAR SCIENCE MONTHLY

2 eat Newest Oil Locomotive Could Light a Town ITH a single controller, similar to that on an electric street car, and an air brake valve, the engineer governs a new 650,000-pound oil-electric locomotive which the Canadian National Railways soon will put into service. The locomotive consists of two units. which may be operated separately, if desired. Each contains a pair of oil engines operating generators which supply electric current.to drive the wheels. The supply of oil carried—about 8,000 pounds —1s sufficient to operate the motors under normal conditions for twelve hours. Each unit also carries 11,000 pounds of boiler water, 3,000 pounds of engine jacket cooling water, 1,000 pounds of lubricating oil, and 3,000 pounds of sand. A motor- driven pump fills the fuel oil tanks. The electric power generated by the engines would be sufficient to light a Odd “Flivver” Craft Rides on Land or Water N AMPHIBIAN “flivver” has been added to the list of land and water boats by Charles Wyborney, of Wilbur. Wash. His unique craft, named Miss Landanwater, slung on springs, is

said to ride as easily on the road as an ordinary automobile. The same steering gear is used in the water as on the land, the front disk wheels acting as rudders when they are turned to left or right. Feathering paddles arranged so they enter and leave the water almost perpendicularly are attached to the rear wheels. These paddles propel the unusual craft through the water at a fair speed with four passengers aboard. Each wheel has three pad- dles eight inches square. The estimated speed of the ma- chine is fifteen miles an hour in water and thirty miles on land. A ha ¥* kwon Beek ey SSR cat seine The speedy amphibian “‘flivver’’ as it appears on water and on land. Paddles on rear wheels drive it in water, and front wheels steer it; thus the vehicle runs from land to water without adjustments.

good sized town, while the apparatus for heating trains from the locomotive boiler water could heat a modern apartment. When the first oil-electric locomotive was installed on the Canadian National Railways, in December, 1925, it estab- lished what is claimed to be a world record by making a continuous run of 2,937 miles from Montreal, Quebec, to Vancouver, British Columbia. Econ- omies effected by the new type engines are expected to slash operating costs. Trees Fed by Millions of Microscopic Slaves ILLIONS of microscopic slaves toil up and down in tubes that extend like flues through the bark tissues of every tree, Dr. Otis F. Curtis, of the New York State College of Agriculture, Cornell, has concluded after tests. Unlike the sap tubes in the woody part of the tree, says Dr. Curtis, the veins in the tissues of the bark region are filled with certain living protoplasm. This protoplasm circulates like an endless belt, moving up one side of the long tubular cells and down the other. The upward stream carries the food salts absorbed from the earth by the roots and the down- ward stream transports the sugars manu- factured by the leaves from the air, so that the tree is completely nourished. The belief in the past has been that the salts and sugars which fed the tree were carried with the water through the woody part of the trunk. Demand for Sawdust Fuel Causes a Shortage A ‘SAWDUST famine” has occurred in lumber manufacturing towns of the Pacific Northwest. For years the mountains of sawdust, accumulating around the lumber mills, were looked upon as white elephants by the mill owners. Recently there was invented a burner attachment that could be con- nected with house furnaces, heaters, or mill boilers to allow them to burn the waste product. So many people installed the burners, it is said, that the sawdust mountains disappeared and the cheap fuel had to be brought by motor trucks, scows, and electric interurban trains from mills as far as 200 miles away. Special mills for grinding waste pieces of lumber into sawdust are now proposed.

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Two Ears Now Can Listen at One Telephone TELEPHONE attachment which permits the user to listen to a long distance call with’ both ears, and in- cidentally allows two people to hear from a single receiver at the same time, has been designed especially for noisy offices. The device is a sound-distributing cham- ber which slips over the end of the standard telephone receiver and sends part of the sound through a rubber tube ending in a metal cup, similar to that on a doctor’s stethoscope, which fits in the opposite ear of the user. Thus the person who is telephoning can listen to the con- versation undisturbed by outside noises, and has one hand free to make notes, the maker points out. When it is important for two people to hear a telephone conversation, one may listen through the standard receiver, the other through the rubber tube. The attachment can be slipped on the receiver or removed in an instant. Larger and Faster Liners to Ply the Atlantic IKE fastest Atlantic steamship cross- ing of history was made recently when the Cunard liner Mauretania reached Plymouth, England, just four days, nine- teen hours, and fifty-five minutes after leaving New York. This time is two hours and two minutes faster than the previous record made by the same vessel last year. The average speed of the Mauretania was 25.26 knots. A liner that is [expected to clip several hours ;from this record is to be laid down soon in France. It will have nearly twice the tonnage of the Mauretania, will be almost a thousand feet long, and is ex- pected to cross the Atlantic at a speed of twenty-seven knots. The engines of the giant ship will develop forty-five thousand horsepower. Another thousand-foot ocean vessel is under construction at Belfast, Ireland. It is being built by the White Star Line for service between England and America. New Red Dye from Cactus ED neckties of a new shade may result from the discovery by a German chemist, Prof. H. Molisch, that a certain species of cactus can be made to produce a natural plant dye. The new dye has been named “cacto-rubin.” It is pro- duced when the cells of the plant die. POPULAR SCIENCE MONTHLY Using the new attachment, the business man and his secretary both listen to a telephone con- versation over the same receiver. Carrying sound from the standard receiver through a rubber tube, the device permits the user to listen with both ears, as below. Reads Name of Explorer on Mystery Rock FLASHLIGHT photograph recently solved the mystery of the strange in- scriptions on Dighton Rock, on the Taunton River,in Massachusetts, which have led to innumerable wild conjectures in the last 200 years. This rock is ex- posed by the tides for only brief periods. The worn inscriptions upon it have been attributed at various times to the Phoenicians, the Norsemen, the lost tribes of Israel, the Chinese, the Druids, and even the inhabitants of the tradi- tional lost continent of Atlantis, the theory being one or another of these peoples once visited the eastern coast of America. Recently Dr. Edmund B. Delabarre, of Brown University, began photographing the mysterious rock by flashlight. A study of the pictures revealed, he reports, that under the inscriptions were the remains of the name May, 199 Cordon of Petunia Vines Guards Against Fires 2 beds are now protecting tanks from fire. In California, * experiment has been tried of planting wide band of petunias around the 4 It has been found that the trailing stems of these flowers will not ignite w burning matches or cigarette stubs are thrown among them. This prevents fires from creeping to the tanks and firing their inflammable contents. In other parts of the state, the sam flowers are being planted along the Toads near woods to act as a protection againg forest fires. ‘% A Cupful of This Poison - Could Wipe Out a City : ONE of the deadliest poisons in world was recently brought from jungles of South America by Dr. §, Williams, of the University of Pittsburgh, Known as “carrere,” the liquid is use by savages to poison the death-dealing darts they shoot from blowguns. The jar of poison which Dr. Williams obtained contains no more than a cupful, but he states that amount is powerful enough to kill every inhabitant of a city the siz of Pittsburgh. He also brought back with him a number of the fatal darts with their poisoned tips. Dare-Devil Fireman Dives 85 Feet into Net A DARING, head-first plunge of eighty. five feet was one of the spectacular stunts exhibited recently by members of the Los Angeles, Calif., Fire Department in the Los Angeles Coliseum. Joe Wynn, dare-devil performer from the rescue squad, crawled to the top of two swaying ladders, braced against each other, while a tiny circle of men on the ground helda fire net beneath him. At a signal, Wynn dropped head first toward the ground. During his plunge, he somersaulted so he struck the net with his back and bounced up unharmed. “Miguel Cortereal” and the date “1511.” Miguel Cortereal is known to have been , one of two Portu- guese brothers who sailed to ‘Labrador in 1501. The other brother sailed home but Miguel, who ex- pected to follow, was never heard of again. The theory is that he wandered south and lived with the Indians in Massachusetts for at least ten years. The fact that the pic- ture writing of the strange inscriptions was placed on top of the faded lettering of the name convinces Dr. Delabarre that it must be the product of Indians who lived in the region later than the year 1511. A breath-taking plunge. The camera clicked just as Joe Wynn, Los Angeles fireman, started his 85-foot dive into the rescue net below. Col QUI how teach st N.J. I New Je them th course 0 cipline « soldiers of an Ar One | day’s ac in squat the supé of the fe ous dist that is include: shoes w ing the are par Hors: stable i rookies The | ampli

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Student cops at pistol practice on the _ school range, where they learn to shoot fast and straight. Treed by the bloodhounds. The rookie police officers take turns at playing the fugitive and pursuer.

College Course in Pistols and Bloodhounds QUEER college which uses blood- hounds, guns, and motorcycles to teach students is maintained at Trenton, N. J. It trains would-be members of the New Jersey State Police Force, putting them through an intensive three month’s course of training. The schedule and dis- cipline of this unique training camp for soldiers of the law is as rigorous as that of an Army camp. One of the important parts of each day’s activity is pistol practice. The men. in squads of twelve, toe a line and, under the supervision of two experienced officers of the force, fire at targets placed at vari- ous distances from the line. The uniform that is worn by the men in mild weather includes a pair of heavy-soled basketball shoes which give them surer footing dur- ing the strenuous athletic games which are part of the training. Horsemanship is also practiced. <A stable is maintained at the camp and the rookies take their turns dashing up and

The Jloudspeaking telephone apparatus, including amplifier and horn, with small radio receiver attached. down the grounds of the training school under the direction of trainers. In ad- vanced classes of the school they learn to make jumps on horseback. Motorcycle riding is another fine art taught at this college for cops. Because members of the state police must be able to repair their machines in case they break down while on duty, a course in motor mechanics is part of the curriculum. Another interesting phase of the train- ing is practice in handling a pack of bloodhounds. One of the men in training attempts to escape from a companion in charge of a pair of the dogs, after which the men change places and the pursuer becomes the pursued, so that each has his turn in trailing a fugitive with the animals. This practical training, together with the rigid discipline of the school, are expected to develop one of the most efficient organizations of expert police officers in the world. Making a Telephone Talk Through Loudspeaker e ILL you speak a little louder please?” That request is un- necessary for users of a new telephone loudspeaker invented by H. O. Rugh, of Chicago, Ill. The installation con- sists of a horn loudspeaker operating from the telephone receiver through an audio amplifier similar to am- plifiers used in radio. The latter is supplied with current from the house lighting circuit and is contained in a small cabinet upon which the tele- phone instrument rests. The turn of a knob is said to lift the telephone receiver automatically so the voice of the person at the other end of the wire can be heard through the speaker. When the tele- phone is not in use, the speaker can be used with a small radio receiver especially designed for the purpose and connected with the amplifier. It is tuned with a dial like any other radio set.

Frogs Can Learn a Simple Problem in Geometry ROGS showed that they could learn a simple proposition in geometry re- cently when a European experimenter, S. Biedermann, tested them. He found that they could distinguish a square from a triangle. Before the frogs, he set square and triangular blocks in pairs. One of the blocks has an insect attached to it. After the triangular block had appeared ac- companied by food for a number of times, the frogs would hop expectantly up to all triangular blocks, ignoring square ones. Biedermann tested several species of frogs and all showed ability to distinguish between different shaped blocks. He found little frogs were the “brainiest.” Tennis Court 400 Years Old, Still in Use IHE oldest tennis court in the world celebrates its 400th anniversary this year. It is at Hampton Court Palace, in England. Other tennis courts, which date back several centuries, have become merely historic spots, like one at Ver- sailles, But the Hampton court, after pro- viding recreation for the English royal family for four centuries, is still used. King Henry VIII, in his youth, dashed across the court in many lively contests, as did Charles 1, who used to play before breakfast. Shakespeare is said to .have visited the court often. HEREVER men are doing new things, advancing new ideas, or making dis- coveries or inventions, there reporters and photographers are on hand to give you the facts in POPULAR SCIENCE MONTHLY. The many stories on these pages cover virtually the whole field of science. Reading them, you will find that they not only keep you in touch with the world’s ad- vance, but give you fascinating glimpses of unusual people and their achievements.

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Track Coach Invents New Toe-Hold for Sprinters I ELAYS in track meets, due to the athletes digging holes for footholds at the start of the race, may be eliminated by a new starting device invented by J. P. Nicholson, track coach at Notre Dame University, South Bend, Ind. It consists of a small metal pipe frame, provided with two wooden pedals that are instantly adjustable to the runner's stride when set. for the starting pistol. The frame can be fastened to the ground by stepping upon the crossbar with both feet and thus driving it into the track. In case of a wooden track, the frame has to be held by a person standing upon it. If a sprinter is penalized, the starter can pick up the light frame and place it back in an instant, eliminating the delay occasioned by the digging of new holes. The photograph shows Coach Nichol- son with Jack Elder, champion Notre Dame sprinter, testing the new starting device. Leaping Car Lands on Another YWO automobiles figured re- cently in a spectacular freak accident near Bishopville, S. C. A roadster, going at a high rate of speed, got out of control and slurred from side to side along the road as it careened toward a car pulled over to one side to let it pass. Just before reaching the parked car, the roadster somer- saulted up an embankment and, righting itself, leaped on top of the standing automobile, where it remained perched until removed. Neither car was seriously dam- POPULAR SCIENCE MONTHLY was hurt. The roof of the under car surprisingly with- stood the terrific impact of more than fifteen hundred pounds crashing upon it. Not one of the supports was broken. Radio Brakemen for Trains IGNALS that ride the ether waves are taking the place of brakemen who used to race along the tops of freight cars swinging lanterns, to relay messages from the caboose to the locomotive. The New York Central Railroad has just asked the RadioCommission for two commercial licenses for a special communica- tion system between the ca- boose and engine of a freight train. The sets will operate on fifty watts power or less. Modern freight trains are frequently a mile long and the new system of wireless communication is expected to facilitate their move- ments. For some time ex- periments have been car- ried on with wireless com- munication between the head and the rear of trains, but this is believed to be the first practical application of the scheme to regular freight service. He Does All the Housework ee ee of a strange ‘‘leapyear bird,” that lives in the Arctic, were recently brought to the Field Mu- seum of Natural History, in Chicago. Among these phalaropes, or swimming sandpipers, the female wears bright plumage and does the courting. The male, wearing somber feathers, builds the nest and sits on the eggs until they are hatched. The birds swim many miles from shore in flocks. aie a4 with sliding arms that telescope And no one was hurt! In this queer accident, the automobile on out over. the vessel’s rail before aged and none of the occupants top did a neat flip-flop and landed on the shoulders of the other. the boat is lowered. May, 19% Power Aqueduct Is Through Italian Alps AN ARTERY, carrying water the heart of a mountain, has ¢ been completed in Italy. The se bore leads through three and a half mils of solid rock in the Italian Alps, bring a flow of water from a glacier-fed a power plant in a valley below. it emerges from the tunnel, which Passe; 3,000 feet below the peak of a mo the water makes a drop of nearly feet, almost three times the height Woolworth Building, world’s tallest hj ing, before striking the turbine w the power plant. It is estimated that the electricity pn | duced by the new scheme will save the equivalent of 750,000 tons of coal, year. As Italy has little coal, its cong. vation is of importance. The station yj supply power to cities within a radius ¢ 140 miles, including Bologna, Verona, anj Mantua. Extension Davits to Aid in Lifeboat Launching. N THREE minutes, a new lifebog launching device will swing a beat twenty-four feet clear of the rail of g sinking vessel, according to its inventor, Henry Lawrence, of London, England When high seas are running and a fom. dering vessel \is listing badly, the distang Henry Lawrence, British inventor, demonstrates model of his extension davits for safer launching of lifeboats. a boat can be swung from the side of the ship and the speed with which it can be lowered into the water during momentary lulls are of prime importance. This was demonstrated in the sinking of the British steamer Vestris a few months ago, when lifeboats carrying women and children were smashed against the careening side of the vessel. The usual davits, or curved arms, lower the lifeboats slowly close to the side of the ship. Lawrence’s invention has davits sf the ai

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S & £5 ibid ~ F E2seF ahi = side ved wly 1p. vits ope ore Altar 3,500 Years Old Is Unearthed in Palestine Mireectvesin} of the University of Pennsylvania Museum expedition to Palestine recently unearthed a great stepped altar at which the Canaanites worshiped their god Mekal about 3,500 years ago—approximately 400 years be- fore the Hebrew tribes from Egypt crossed the Jordan into the Promised Land. The Canaanites, according to the Old Testament, were the descendants of Canaan, the son of Ham and grandson of Noah. The altar, found in the Mekal Temple at Beisan, the Biblical Beth-Shan, is six- teen feet ten inches wide, eleven feet ten inches deep, and about three feet high. It is made of bricks resting upon a foun- dation of undressed stone. It contains four steps, the lowest of which is much wider than the upper one, and has a balustrade on either side. Archeologists consider the structure the most remark- able of its kind ever excavated in West- ern Asia. Next to the altar, members of the ex- pedition discovered a small room contain- ing a low seat and also a sloping socket that was once used to hold a wooden peg. From its position and appearance, they deduced that this room was occupied by the temple guardian whe kept watch with the aid of a fierce hunting dog, probably tethered to the peg. A number of objects of great archeo- logical importance were uncovered by the expedition, including three gold pend- ants, one of which bears the figure of the goddess Ashtoreth and a number UT of the dust of ages, archeologists bring us the story of the beginnings of civilization. From the deeds and works of the present, writers for POPULAR SCIENCE MONTHLY report the story of modern progress and build a picture of the future. The | scores of stories and pictures on these pages each month represent history in the mak- ing. Every issue keeps you up-to-date with the swiftly moving age in which we live. POPULAR SCIENCE MONTHLY of bronze arrowheads. In connection with the find of the guardian’s room and the peg socket for the watchdog, leaders explain that some time ago the party found a magnificent basalt panel depicting lions fighting with dogs. They believe this panel was placed against the door of the temple and that the dog was repre- sented as defending the temple against a lion symbolical of destruction and death. Skipping Heartbeat Not Always Danger Sign F YOUR heart beats irregularly at times, it does not mean that there is anything wrong with it. Normal hearts are often irregular, says Dr. Milton J. Native workmen dragging a sledge loaded with a magnificent basalt panel found in temple ruins at Beisan, Palestine, by the University of Pennsyl- vania Museum expedition. The great stepped altar at which the Canaanites worshiped their god Mekal 3,500 years ago. It is said to be the most remarka- ble structure of the kind ever discovered in Western Asia. ! Raisbeck, of New York City. Extra beats, he believes, are carefully planned by Nature to insure continued beating. Some cells of the heart are pacemakers, governing the rate of beat, as a timer in an auto regulates the rate of explosion. These “timer” cells change their pace, especially when you rest after exercising. When the change comes quickly, Dr. Raisbeck explains, some of the cells are unable to keep to the pace and the heart gives extra or irregular beats. Students Now “Fly” without Leaving Ground l= the sensations of looping the loop, going into a tail spin, and flying blind through fog are afforded students of the Army Air Corps at Wright Field, Learning to climb in the “‘ primer plane.’’ The stu- dent experiences all the sensations of a real flight. Dayton, Ohio, by an ingenious “primer plane” that never leaves the ground. A miniature fuselage, fitted with a pro- peller, ailerons, elevators, and rudder, is attached to an electrically-operated framework, and in the cockpit a prospective pilot does his first “flying” in safety. With his feet on the rudder bar and his hand on the “‘joy”’ stick, with the propeller roaring before him and the air rushing past, the student puts the device through va- rious evolutions. Each movement of the control stick or rudder bar results in the same reaction that follows such a movement in actual flight. Thus, the beginner becomes familiar with the controls without risking a crash. A second lever and bar allows an instructor, ‘outside the device, to maneuver it suddenly into all sorts of positions to test the student’s ability to react coolly in a crisis. If an error is made, the motor is shut off and a conference takes place. On the instrument board of the “primer plane”’ practically all the instruments carried in a regular airplane are mounted. “Blind” flying is taught by placing over the student’s head a hood that shuts off the. horizon but permits him to watch his instruments.

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Grid-glow tube receiver which turns on lights in response to sound of a plane’s siren. HE other night an air-mail pilot circled over the darkened airport at Newark, N. J. Reaching out of the cock- pit, he pulled a cord. A wind-operated siren, attached to the wing, screamed through the darkness. Instantly a blaze of lights, totaling 24,000,000 candlepower, flooded every corner of the huge landing field below. That pull on the cord had turned them on by sound! A sensitive “electric ear’’ on the ground had caught the sound of the siren and had relayed the signal to a robot that threw the light switch. The latest attempt at automatic control of airport lighting had proved a success. Some time ago, attempts were made to have the sound of an airplane motor, as it approached a field in the dark, turn on the lights. The device worked too well. Every time a motor on the field was started, its noise was picked up by the apparatus and the lights flashed on! The latest method eliminates this dif- ficulty, for the robot is set in action only by the high-pitched note of the siren. The “electric ear” which catches the sound is somewhat similar to a radio re- ceiving set. A radio receiver is tuned to receive certain wave lengths. This device is tuned to receive certain tone frequen- cies. When the pitch of the siren note POPULAR SCIENCE MONTHLY May, 1999, Plane’s Siren Switches on Airport Lights! Left: A m equipped with wines passing above the “electric ear’ : above a hangar Newark, N. J., cpa At the lower left the floodlights, turned on by the siren’s sound, Below: An air. pilot pulling the aa which sounds the wind. 2 driven siren seen at the oe a left of the cockpit, 4 small propeller whirled by wind rushing pas the plane in flight operates the siren, rises to a certain frequency, the device responds by setting up electrical impulses. These pass through grid-glow tubes and relays that amplify the impulses until they are strong enough to actuate the “televox” robot to turn on the light switch. A small propeller, turned by the rush of wind past the plane, operates the siren, which can be set for any desired tone frequency. The “electric ear” can be adjusted to respond to that pitch. Beebe Angles for Strange Fish with Radium Bait HE rarest fish bait in the world will be used by William Beebe, famous deep-sea hunter, when he lowers hooks coated with radium to attract fish in the black waters off the coast of Bermuda. The amount of the precious substance on the hooks will be slight, as they will be coated with a radium paint similar to that used on the hands of luminous watches. The strange hooks are designed New Biplane Goes the Limit in Wing Stagger for use in water deeper than 1,700 feet where, according to Beebe, complete darkness reigns. Using Nonsuch Island, near Bermuda, as a base, Beebe and his party, which recently sailed from New York, will comb the ocean thousands of feet below the surface in search of new and rare specimens of sea life. Nets, secured to sounding wires, will be dropped to the ocean bed to catch strange fish for ob- servation. The specimens will be placed in tanks cooled by refrigeration and kept under water pressure approximately that of their original environment. Beebe plans to be gone about six months. Dark rooms are to be fitted up for studying luminous tropical fish. To col- lect surface specimens, Beebe will use percussion caps to stun the fish so he can pick them out of the water. ESIGNED at Darmstadt, the birthplace of the record- breaking German gliders, a new motored biplane of unique design is attracting wide attention. The machine is named’ the D-18, and was designed by Friedrich Fechner. Its wings have an un- usual stagger. The top wings are so far ahead of the lower ones that their trailing edges are almost directly above the leading edges of the latter. The theory is that this will give greater lifting power. The pilot’s cockpit, placed back of the lower wings, is said to give excellent visibility in practically all directions. Like the Darmstadt gliders, the new machine has in- | ternally braced wings. A side view of the unusual new biplane D-18, designed at Darmstadt, Germany, home of the famous motor- less gliding machines. Notice how the upper wing has been set far ahead of the lower to increase the lift. ee It won't lumber RE: the freight fireproo cess Jus tion. 1 but fort ber alt! cording or vape the cyl or in « process vacuun nomen: or split resilien the dr gallon, Lum can be resider it also and of able fo firepro tains | —one exting' anothe of the: a prot Cem born f Whitt down them the fii guishe ‘on fi

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1929 BRSARE ESE PREER> FER —a So @ = a? Sa ‘on fire in the neighborhood of May, 1929 Amazing New Fireproof Lumber Promises Safer Houses POPULAR SCIENCE MONTHLY It won’t burn! Testing sticks of fireproof lumber over a flame in the laboratory. REAT cylinders of steel taller ¢ than a man and as long as a freight car make building lumber fireproof, and dry it, in a new pro- cess just put in commercial opera- tion. The entire treatment takes but forty-eight hours after the lum- } Through this eight- it foot door, lumber stacked on a car enters a huge cyl- inder where it is impregnated with fireproofing liquid. Left: The combi- nation fireproofing and drying cylin- der. In the fore- ground is ‘machin- ber arrives from the sawmill, ac- cording to George H. Storm, presi- dent of the eastern firm that has devel- oped the process. A carload of lumber to be treated rolls through the cylinder’s eight-foot door, which is then heavily bolted. A vacuum pump chugs for an hour and a half. Then, at a valve’s turning, fireproofing liquid spurts into the cylinder and penetrates to the deepest pores of the wood. A pressure pump forces in the last of a measured number of gallons. Moisture in the boards is then removed by a recently-invented high speed dryer or vaporizer of unique design, attached to the cylinder. It may be used separately or in conjunction with the fireproofing process. Vapor is circulated in a partial vacuum, drying the lumber in a phe- nomenally short time without checking or splitting, and leaving the wood soft and resilient. From a condenser attached to the dryer comes running water, by the gallon, actually drawn out of the boards. Lumber fireproofed by the new process can be used for every part of a private residence, including the shingles; it also offers safety in factories and office buildings and is adapt- able for countless other uses. The Shenandoah, Pa., a few weeks ago, a creek was diverted from its course and run into the mine to put out the blaze. After the burning coal had been flooded, the creek was turned back into its course. Would Blast Arctic Ice to Keep Us All Cool EGULATING the temperature of the world by breaking off ice cakes from Greenland and the Antarctic Continent is suggested by Herbert Janvrin Browne, a meteorologist of Washington, D.C. As we regulate the temperature of a room in winter by opening a window and allowing cold air to come in, so the heat of sum- mers all over the globe can be moderated, he believes, by “opening the windows” of the Arctic and Antarctic and letting more icebergs into the oceans. The bergs that float down from Green- land into the North Atlantic affect the climate of Europe favorably and prevent droughts, Browne points out; and the Milk Now Delivered in ery which extracts lumber’s moisture. Antarctic ice, carried northward, has a similar beneficial effect upon the climate of Australia. The plan suggested is for the countries of the world to coéperate by sending battleships to shoot off huge chunks of ice from Greenland and the Antarctic. Browne thinks the bergs can be started at points where known ocean currents will carry them to positions in the ocean where their cooling effect is needed. Tail Lamps for Elephants the Law in Ceylon UMPING into elephants in the dark’ became such an annoyance for mot- orists in Kandy, central Ceylon, that they induced the municipal council to pass an ordinance compelling all elephants to wear lights. In the dark, the huge, shadowy, gray beasts of burden cannot be seen until the automobile is almost upon them. The law requires the animals to be provided with head and tail lights. Handy Paper Bottles fireproofing compound itself con- tains three principal ingredients —one that gives off a flame- extinguishing gas when heated, another that blocks the pores of the wood, and a third that forms a protective surface coating. Cement Helps Put Out Oil Well Fire NUSUAL methods were used recently to conquer two stub- born fires. In an oil well fire near Whittier, Calif., cement was forced down near-by well holes to block them and prevent the spread of the fire While it was being extin- SPEEDYmotorcycle, it is said, can haul as much milk in new paper containers, recently intro- duced by a New York dairy con- cern, as a wagon can deliver in glass bottles. The cone-shaped containers can be packed upright and inverted so that two quarts occupy little more space than .a._ one-quart bottle. Moreover, two quarts in paper containers are- said to weigh only seven ounces more than one quart in a bottle. Before filling, the containers are paraffined to make them leak- proof and air-tight. After filling, the top is sealed with a metal clip. guished. When a coal mine caught Filling new paper bottles at the milk distributing station. The containers are treated with paraffin to make them leak-proof, To open the new paper bottles, the top is cut off below this clip.

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74 Comfort Behind Brick Wall A Noted Architect Tells, from Actual Experience, How to : Combine Charm and Durability in an Economical Home POPULAR SCIENCE MONTHLY By WILLIAM DEWEY FOSTER RCHITECTS frequently, and home builders as a rule, are more interested in the design and appearance of a house than . in the materials and methods used in its construction. This is because many architects are at heart artists rather than constructors, while the general pub- lic is not aware of the importance of struc- tural details. Yet hidden away in the detailed problems of house engineering are many of the factors which six-by-eight-inch beams which are spaced three feet six inches on centers, forming an exposed ceiling, no plaster being used. While the beams are heavier than the usual floor joists, their weight permits spacing them farther apart so that the cost is about the same, though the effect is much finer. The planks are tongue-and- grooved, making them tight, and are heavy enough to deaden most sounds. On the remainder of the second floor, where the concrete slabs occur, the fgg has been covered with linoleum. ; perhaps, a luxury, but it gives a nent surface which is easily cleaned, ~ There are eight-inch hollow brick wall separating the garage from the with an automatic fire door to the entry, The remaining partitions in the house are of two-by-four-inch studs of fir covered May, 19% with wood lath and plaster on the second floor except in the hallway—and also at determine the value of a house and the satisfaction it will give. A striking example of how simple, sound construction can be combined with out- ward charm and rigid econ- omy is a brick-walled house built in Ravinia, a suburb of Chicago, by Harry Howe Bentley, architect, for about $12,500. The cost was kept down by eliminating unneces- sary details and by depend- ence on simple materials. The outstanding feature of this house is the method of building the brick walls, but first 1 wish to give you an idea of its specifications. The foundation walls are of concrete and inclose a cellar which is under only the cen- tral portion of the house, merely enough for the heat- ing plant, coal storage, and a small laundry. This small cellar, of course, saved on the ON HOLLOW TILE Two ways of keeping a brick wall dry on the inside — brick veneer applied to a wall of hollow tile, and furring strips nailed to brickwork. Eight-inch brick wall construction allow- ing two-inch air space for insulation; also use of brick veneer, instead of siding, on two-by-four studs. "al LATH AND WSXSQyf Se S NN . 3 Sy FURRING Zt ,: STRIPS ON 16 C. aa 4" RUNNING rae Se = : 4. Brick, VENEER 8 BRICK WALL FURRED & PLASTERED 7 bea COURSES =H PLASTER 2° AIR BUILDING PAPER ~~ \N bo Gm 4" BRICK VENEER ON 2°x4" STUDS cost. of excavation and also permitted the use of brick for the floors of the breakfast room and kitchen without special floor slabs, as would have been necessary if it were excavated under that portion. EINFORCED concrete floor slabs were used, however, for all the second floor except over the living room; that is, where the fire hazard was greatest, especially over the garage and kitchen. In addi- tion, a concrete slab under the entry forms the top of the coal storage space, making that area tight against dirt and coal dust. The living room, then, is the only space in the first story where there is a wood floor, and it is of edge- grained fir, seven eighths by two and a half inches. Over the liv- ing room is a single flooring of yel- low pine planks about six inches wide and one and five eighths inches thick. These planks span across the stair end of the living room — where molded pine boards have been placed vertically, nailed to horizon. tal strips on the studs. This is as cheap as where plaster is used and makes an attrac. tive finish. OU will notice in the photograph of the living room, to the left of the fire. place, a small black door, This is the incinerator door, An incinerator was desired and yet to have one whereit could be used from the kitch en would have necessitated another chimney. Accord- ingly, it was decided to have another flue in the main chimney for the incinerator and use it only when guests were not present. The im cinerator itself is in the cellar of the house. Hot air has been used for the heating system. This is cheaper to install than steam A corner of the ‘disidhe but attractive living room in Mr. Bentley’ s brick heme. ~ Notice, at left of fireplace, a small incinerator door. Installing the incinerator in this manner saved the expense of an extra aiamel

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or hot water, and it works satisfactorily in a small compact house. The roof is covered with sixteen-inch red cedar shingles. Here, again, a fire- proof material such as slate or flat shingle tiles would have made a safer and more lasting roof, but for economy wood shingles were used. Well-stained shingles usually will last from fifteen to twenty years. Copper has been used for all flat Front and rear views of the Bentley brick-walled house at Ravinia, IIl., built for $12,500. The cost was kept down by use of simple materials and the eliminating of nonessentials. =e fae ally sound wall, a course is then laid in Flemish bond, which is composed of a “header” (a brick which is laid so that the end shows and the eight-inch length is entirely in the wall), and a “stretcher” (a brick laid flat and showing the eight-inch length on the outside), alter- nating so that the header car- roof surfaces and flashings. Poor f- flashing in these vital spots may |! cause much damage. HE brick walls of the house are_ || laid according to what is known ‘| as the “ideal” method. This gives a wall eight inches thick, of which two inches is an air space acting as insulation against cold in winter and heat in summer. It also keeps moisture from penetrating to the inside wall. The outside part of the wall is constructed with six courses of bricks laid flat, in the usual way. At the same height on the inside are || to build, the best yardstick, after all, is the actual experience of others who have met the same problems you are facing. In this in- teresting article an experienced ar- chitect leads you through a new brick-walled dwelling and shows you its fine points—its economies and details of construction that spell lasting comfort and _ satisfaction. I PLANNING the home you want +? OPTS wes: the cheapest form of brick wall where the inside must be dry, as in a house. When a solid eight- or twelve-inch brick wall is erected there is chance that mois- ture will be driven through the mortar joints, and even in some cases through the actual bricks where the side is exposed to driving rains. One way to guard against moisture is to fur the inside of the wall. That is, one-by-two-inch strips laid flat are nailed vertically to the brickwork and then to this is applied lath and plaster, ~ tet oot ae leaving a space between the back of the plaster and the brick. This space of one inch is not always ade- quate, however, since waste plaster ||. may drop behind the lath and ac- || cumulate, forming an area of direct |} contact between plaster and brick which will conduct moisture and spot the inside wall finish. Heavier furring strips which will give a two- inch space are sometimes used to avoid this difficulty. A variation of this method is to | make the furring the structural part - of the building and let the brick be four courses of bricks on edge, show- ing the four-inch faces. This gives two practically independent walls, one four inches thick on the outside, and the other two inches thick on the inside, with a two-inch air space between. To tie these two together and form a structur- “FIRST FLOOR: PLAA LS =r kT First-floor plan of the Bentley house. Hollow brick walls separate the garage from house. ries through the entire eight inches of wall and forms a strong tie, or bond, every seventh course in the height of the wall. A sketch shows how this bonding is effected. The inner face of the wall, protected by the air space, is dry so that plaster could be applied directly to it, without the usual furring and lathing. In this partic- ular house, however, Mr. Bentley elimi- nated the plastering for economy, and also because he wanted the effect of ex- posed interior brick walls. As a finish for the brick he has painted both the inside and outside walls with a creamy white waterproof paint. HERE might be some doubt as to the warmth of these walls in winter, but they have proved very efficient. The fuel bill for the past winter, burning coke in the hot-air furnace, was about $130. This low cost no doubt is due not only to the efficiency of the walls, but also to the use of special insulating material for the roof. The “‘ideal’”’ method was used here for economy primarily. Undoubtedly it is a veneer. In this case two-by-four- inch studs are used, or two-by-six-inch studs if the appearance of a thicker wall is desired; they are erected as for a frame house. Sheathing boards and building paper are then applied to the outside of the studs, as when wood shingles or siding are used. But (Continued on page 147) PLAS tt" {107 SECOVD © [LOOR-- Plan of second floor. Reinforced concrete floor slabs were used, except above living room.

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Within a handsome table that stands unobtrusive- ly against the wall is concealed a comfortable bed—-the latest in space- saving furniture. If an unexpected guest arrives it is opened in a jiffy. Hedge trimming is made easy with this speedy electric clipper which operates at the end of a hundred-foot cord from any light socket. The cutting knife rotates at 5,000 revolutions a min- ute, and is said to leave a smooth surface diffi- cult to attain by hand. Since it weighs only five pounds, a woman can operate it easily. Snip—and off goes the top of the boiled egg. Squeezing the handles on either side of this ingenious egg cutter rotates a series of sharp steel teeth, seen in the upper picture. These slice the shell cleanly and decapitate the egg while it rests in the cup. The Paris restaurateur who invented the device claims that it not only makes the soft- boiled egg look more appetizing, but prevents getting bits of broken shell \ in the egg and spoiling the breakfast. POPULAR SCIENCE MONTHLY May, 199) May New Devices for ome Makers This novel can opener with curved blade “‘walks around” a can’s edge of its own accord, it is said, when the handle is gently rocked back and forth. A hook on the utensil serves as a bottle opener. | i § t f t The table-bed opened. A reassur- ing safeguard for those afraid of being pinned in folding beds is the fact that the table top, backed against the wall, cannot close with the sleeper inside. Both single and double size beds are available. How many inches long? How many feet? You'll never want for an answer, with this handy meas- uring kit in the house. Hanging against the wall from a hook, it has a series of pockets containing tape measure, foot ruler, and folding yardstick. It is; enameled with a bright decorative pattern. Windows can be locked in any position with this device, clamped to the top of the lower sash. Its ‘“‘business end” is a rubber cap held against upper pane by a spring. Trying to move either sash jams the rubber tightly against the glass and wedges the window fast.

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POPULAR SCIENCE MONTHLY Six little bottles in this handy set contain all the ingredients for re- moving common spots from clothing. One liquid takes out grass and fruit stains; another, tar; a third, rust and ink spots; and a fourth, grease. Paint and scorch are removed by the two other solutions. This new lightweight polishing machine has twin brushes of soft hair to produce a shell-like luster. All metal parts are recessed; the machine can operate tight up to the baseboard and around table legs. Electricity now dries the laundry, making the housewife independent of the weather. Adjustable, removable rods in this drying cabinet give a total hanging space of more than thirty feet. It can act as a plate warmer, too. Designed especially for for- warding soiled clothes through the mail, a stout little case of fiber board affords an ideal way or sending laundry home. Its light weight assures a low postage rate, while in the cor- ner is a holder in which you may insert an address card, An unusually attractive lighting arrangement for the dining table, sideboard, or console combines three electric lamps of the can- dlestick type with a flower holder as the base. The lamps, with their delicately pleated shades, are obtain- able in different colors. . 4 5. Siete. * ae Wet is * A dishwasher built into the faucet is one of the latest inventions for lightening the labor of cleaning dinner plates and saucers. A touch of the lever at the center of the faucet diverts water through the upper swinging arm, whence it issues from a nozzle in a powerful spray. Pressing a button on the side of a soap chamber immediately releases a measured quantity of soap powder to aid in the washing.

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Duplicating POPULAR SCIENCE MONTHLY May, 1999 an Antique Mirror At Small Cost You Can Make an Exact Copy of a Fine Old Walnut Frame Ornamented with Graceful Scrolls By FREDERICK J. BRYANT, Author of Working Drawings of Colonial Furniture ALNUT is being used so extensively in furniture today that it seems appropriate to suggest a small piece in this beautiful wood for the man or boy who enjoys making furniture in his home workshop. For this reason a small walnut scroll mirror has been selected. It is easy to make and will add charm to any room in which it is placed. The mirror from which the drawing below has been made is an antique and dates back to about the year 1790. Reproductions of this style are quite popular. It is interesting to note that almost all of the walnut mirrors made between 1775 and 1800 had scrolls similar to this one, so the irregular outline is not a “hit-and-miss”’ pattern. General directions will be given for making an exact copy of the original frame, but if you prefer to have a more modern adaptation, picture molding can be used. It is also possible to take a ready-made frame and add scrolls to carry out the effect; the color or finish in this event will be a matter of personal choice. The materials needed are 2 pcs. pine % by % by 11% in. and 2 pes. 1% by 5% by 9% in. for frame; 8 pine corner blocks \% by \ by 1% in.; 6 wedge blocks 4 I WALNUT ; SCROLLS I” SQUARES oe G L HOLES FOR ff 7 PICTURE J CORDA H ~ > A . FF t ‘ KD Z f -—: 5 INT * += GRAIN >= e4e=-t- ; eee EP GRAIN 5 a “Hh | MIRROR 8% x 10% | y NOT BEVELED aay | Ny | 4 CORNER BLOCKS - a een dS CORNER BLOCKS | Vax Vax ty” Front and edge view of the mirror with an enlarged cross section and a sketch of the half-lap joint. The scrolls are % in. back from the front face. This mirror, made about 1790, is a valuable antique, but it can be reproduced easily by any painstaking woodworker. by \% by 1% in.; 1 pe. walnut 3% by 44% by 95¢ in., 1 pe. 3 by 24% by 95% in., and 4 pes. 3 by 114 by 5% in., for scrolls; 2 pes. walnut 3¢ by 1% by about 12 in. and 2 pes. 3% by 4 by approximately 10 in. for face moldings; 1 pe. paper back- ing 91% in. by 11% in. First make up the pine frame, 954 by 11% in. on the outside, fitting the corners with half-lap joints. Then prepare four facing strips of walnut as shown in the sectional view of the drawing. These pieces measure 3¢ by 1% in. and are glued tothe pine frame. Each corner joint this time is to be mitered. Now lay out a half pattern of the top and bottom scrolls on a piece of stiff paper. This is done _ by drawing 1-in. squares on the paper and marking the points where the scroll outlines intersect the lines. Check your work care- fully against the smaller squares shown on the drawing. Only one full size pattern is needed for the side scrolls, as all four are alike. Cut the paper outlines with scis- sors or a pointed knife. Place your half patterns on the scroll material and mark around the edges with a sharp pencil. Now turn the patterns over and mark the stock for the opposite sides. This is a sure way of getti both sides alike. Saw the outlines on a jig saw or use a coping say, Sandpaper the edges before gluing the stock to the frame. The scrolls should be placed about 1¢ in. from the front face of the frame. Reinforce the work by gluing corner blocks in back of each scroll, Drill two small holes diago- nally through the top member of the frame for the picture wire or cord, which is shown by the dotted line A. When you have sandpapered the mirror frame thoroughly, apply one coat of walnut oil stain or wood dye and wipe off the surplus. After the stain is dry, brush on a thin coat of orange shellac. Rub this down with No. 00 or finer sandpaper and give the frame a second coat of shellac, rub- bing it similarly. You may apply as many as six coats in this way, unless you prefer to follow the more conventional method of using a filler. In that case, fill the grain of the wood with walnut colored paste wood filler after the coat of stain and before applying any shellac, except, perhaps, one exceedingly thin coat consisting of one part shellac to about three parts alcohol. This so- called “wash” coat of shellac prevents the filler from affecting the stain in any way. After filling the grain, finish with one coat of shellac and two of varnish. Those who are using picture molding or a ready-made frame may take their choice of stain and shellac, colored brush- ing lacquer, or enamel. Painting Over Red Stain jr APPLY white, cream, or other light tints of paint or enamel over old mahogany colored doors or wood trim is difficult because the red stain is likely to penetrate the finish and give it a pink coloring, no matter how many coats are used. If the mahogany stain has been varnished over, do not remove the varn- ish; sandpaper it lightly and apply the first coat of paint or enamel undercoat directly on top, adding a small amount of varnish to it. Sometimes it is almost impossible to stop the red stain from coming through. To remedy this condition shellac, japan coach black thinned with turpentine, and aluminum bronze are used. Ina stubborn case, all three may be necessary. May, 1! Fig. 1. That in metal is in the hamme! hollow « positior when t shape © The | and cor the me hollow of cloth The siz of woo of the size of with w in ham Fig for t

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LY, 1999 May, 1929 POPULAR SCIENCE MONTHLY 79 Bowls Made with a Hammer Plain Disks of Copper or Brass Are Beaten Over a Shallow Depression in a Heavy Hardwood Block Fig. 1. A shallow bowl 6 in. in diameter size and type for the beginner. That in the right-hand column is 5\% in. —a good ANY different bowl forms of the shallow type may be made by the embossing or “inside ham- mering” method. A disk of metal is placed over a small hollow carved in the top of a wooden block, and the hammer blow is aimed directly over this hollow each time the metal is struck. The position of the metal over the hollow when the hammer falls determines the shape of the bowl as the work goes on. The hammering is started in the center and continued around in a spiral fashion, the metal being stretched down in the hollow in much the same way as a piece of cloth is pushed in an embroidery frame. The size of the hollow carved in the block of wood has nothing to do with the size of the bowl; that is determined by the size of the flat disk of copper or brass with which you start and by your skill in hammering. Large bowls up to 14 or 16 in. in Fig. 3. Using the hammer to stretch the metal down at the bottom to form a base for the bowl. Note position of hands. By EDWARD THATCHER The indentations in this flowerlike bowl, which is 9 in. in diameter, were made with wooden tools by the method shown in Fig. 9. Fig. 2. diameter may be made in this way after a little experience, but they should be hammered on a stout canvas bag filled with sand instead of over a hollowed wooden block, as it is difficult to guess where a hollow is under a large bowl. The. sand yields under each hammer blow, yet supports the metal under the hammer. If you have not done much of this sort of work, it is better to start with small, shallow bowls 5 or 6 in: in diameter. In making bowls by this method the outside diameter does not change very much for shallow forms; but if the bowl is to be fairly high on the sides, it is usual to allow from one quarter to one third more in diameter than the diameter the Fig. 4. The hammering is done in gradually larger spirals until the edge of the disk is reached. Fig. 5. At the right is shown how a firm base may be obtained by gently driving in the bottom of the bowl. Fig. 6. ‘How to scribe a line around the bowl as a guide for cutting off the surplus metal. finished bowl is to be—this also will de- pend upon your skill with the hammer. High-sided bowls or vase forms are made in quite another manner, which will be described later in the series. The bowls shown in Figs. 1 and 2 were made on the wooden block. The wooden block on which the ham- mering is done may be of maple; beech, or almost any close-grained hardwood, 3 or 4 in. square and about 6 in. long. It may be held in the vise when hammering, or the hammering may be done on the end of a stout log of hardwood about the height of the workbench, fastened to the shop floor with angle irons. Various hollows may be carved in the top of the log. The ordinary size for this sort of work is about 14 in. in diameter and 4% in. deep. The top edges are well rounded over to meet the flat surface on top of the block, as shown in Fig. 7. The hollow may be carved on the top of the log or block with a gouge and hammered down smooth with the embossing hammer, or it may be burned in with the aid of a red-hot iron rod and then hammered smooth. The ends of the embossing or silver- smith’s hammer are only slightly rounded; a sharply rounded hammer like a ball peen hammer will dent the metal too much each time it is struck and leave an unattractive, pebbly surface. To make one of these bowls, cut out a disk of No. 18 or 20 gage copper or brass (copper is much easier to hammer than brass). See that it is well an- nealed and flat and also as clean as possible, as any dirt or oxide on the surface of the metal is apt to get hammered in and prove difficult to polish off. In prac- tically (Continued on page 125)

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ae rE —, ——— — 7 = ee ee eee ss - SP ate oki ck ie alias = Peet z 6 Frees POPULAR SCIENCE MONTHLY

Fig. 1. The little plane as it appears in flight. The original model, built by Paul Shifter. Smith, made a record flight of 6,024 feet and remained in the air 9 minutes 42.2 seconds, A Model for Long Flights How to Construct a Duplicate of a Plane Which Holds Two World’s Records in the Tractor Class By VincEnNT L. J OHNSTONE, with permission of Paul Shifler-Smith OR distance and duration in a tractor airplane model, you will find no better design than that developed by Paul Shifler-Smith and illustrated in Fig. 1. His original model (Fig. 3) established what is, at the time this is written, the world’s record of 9 minutes 42.2 seconds, and it also set the distance record of 6,024 feet for hand- launched tractor models. Although the wing of the model is double covered and the motor stick is of the latest hollow spar pattern, you will find the plane is relatively simple to build. The wing. fin, propeller, and Besides the materials listed on page 124, you will need small round-nosed pliers, high-grade wire cutting pliers, a sharp knife, Nos. 4% and 00 sandpaper, both large and small camel’s-hair paint brushes, several dozen common pins, a ruler, a hard, sharp pencil, some corru- gated cardboard, and a metal bar, piece of pipe, or soldering iron, for forming the bamboo. The wing, 4 in. in chord and 36 in. in span, is based upon the German Géttingen 81 wing form. Make the center rib of \¢-in. balsa wood and the other ten ribs of '/x-in. balsa, as shown in Fig. % Lightening holes are not necessary. Dip the rear ends in ambroid type cement for about % in. to stiffen them. Also make ten false (short) ribs of '/2-in. balsa. Bend a piece of 34 by \% in. bamboo to the shape of the wing tip, split into two halves, and scrape the two tips until they are uniformly 3; in. in diameter. Small 3,-in. square bamboo pieces ex- tend from the outer rib to support the wing tip as shown in Fig. 2. Note that the wing beams extend only to the end rib and that the front wing beam is on top and the reat beam on the bot- tom.

While the trail-

ing edge can be made of thread,

Shifler-Smith used

‘6 by 3% in. bam-

3 ™ P e vd . o i" ° = * julien antler ase % exh pee LTHICK, /—3}%—| 7 bo THICK 42% %> % ROUND. + SSeS Se eee re eresrrerrer a? ei ee 7 detachable so that é i r ; at y Z- | = y m.! i the model can be a a ce: Se ae wee rprracaseudan = ~)s : 4 % ’ ’ in = carrie d con- audios quswniroregsawbnrsasessgnras FE seegess4s Z $ [ | veniently to and ee Ee ee TT I i from the flying 7 xe field. ; ENTERING EDGE TRAILING EDGE ~ xe Larger drawings LOCATE SS on of the model than —SENTER OF Graviry. <= , x - it is possible to ENTERING EDGE. 1° FORWARD 3655 153 F; oN . 3 ig toh” # ALSE : publish in the ee 6*4%O% RIB fal RUBBER \? y. magazine can be a ‘" a WIND —

obtained by send- ing for PoruLar Science Montn- ty Blueprint No. 104 (see page 106). | LOCATION OF WING ON MOTOR BASE

boo scraped to 8 knife edge at the

Fig. 2. Top and front view of the wing; a section through the wing drawn on a larger scalé to show shape of ribs and false ribs; sketch of the tip construction; diagram showing location of wing.

rear. Wing clips (Figs. 6 and §) must be made of No. 11 music wiré to fit the hollow spar snugly yet not so tightly that they might

see ma is 1 tha vie \. the hay SAW Owe | am 932, KX X

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May, 1929 it. The wing should have about Teree incidence; that is, when the trailing edge is flat against the motor stick, the entering edge of the wing should be about % in. above the stick 2 es cardboard, make a full size drawing of each half of the wing. Slip the ribs on the beams, line them up, and fasten them with as little cement as ible, although the joints must be strong. Hold the entering edge and the false ribs with pins. Cement the tips and braces. Attach the trailing edge and then join the two halves of the wing together by support- ing the tips at 23¢ in. above the bench (Fig. 8) and ce- menting the joints several times, especially on top, and later on the bottom edges of the spars. The sides of the spars need only one coat of cement. When the cement is dry, attach the wing clips and cover the wing with very light Japanese tissue paper. To get the correct camber on the bottom surface, it will be necessary to stick the paper to each rib, to the rear wing beam, and, of course, to the entering and trailing edges. Dope the wing surfaces, but be careful that the top and bottom surfaces do not stick together. If they adhere anywhere, pull them apart by using a pin stuck through the cover- ing while the dope is yet moist. ee CEMENT ALL PART. ‘ee ARTS $7 NOSE , INDED) C BEARING : —_ — PLUG $.Lq. DRILL FOR : q ase wo } etme \i i REAL ws ‘ ot, CEMENT Not | SS — STABILIZER Al FIN | Yala DETAIL ay (13 oF FIN \ l FASTENING : 24-3 te2tei — 7°—+ 4 fee | Fig. 3. Paul Shifle won a $100 prize for him. POPULAR SCIENCE MONTHLY to pull the surfaces back again. The complete wing should weigh about .4 oz. if it is made with a bamboo trailing edge. The motor stick (Fig. 4) is a hollow spar, although the model can be made to fly satisfactorily with a solid balsa motor stick and a somewhat smaller propeller. Saw out the 5 by % by 45 in. motor stick in the form of a channel with one of the 5¢-in. sides open, as in Fig. 7. This is best done on a small circular saw. If you have no saw and are unable to purchase ee eng a channeled stick from a model supply house, some carpenter or manual training instructor will probably be glad to make it for you. Do not attempt to do it your- self without experience, because of the danger involved. Sandpaper lightly and uniformly the outside and inside of the channel and prepare a cap strip of 44 by % by 45 in. balsa. Apply a coat of paper cement or thick banana oil to both pieces. When this is dry, lay the cap strip on the chan- Ss Loe SS oF — oa Zs Ty. aponnes 3 : - . \ | 44x i = "4 Wee = “Abert To #13 MUSIC WIRE BEARING = bb hy " Wy2* eq 1-REQ 1- REQ. MOTOR BASE AND REAR END ASSEMBLY Fig. 4. The hollow spar or motor stick with “ho SD | Ol horizontal stabilizer. Note the detachable fin. . | Bruscw CF , P #1 ; _ Before the dope is completely dry, it oo 1- REQ. REAR HOOK is most important to twist the wing so #11 MUSIC W. #13 MUSIC W that the right wing tip—the right wing 3-RE viewed from the front—will have about ¥-in. additional incidence to counteract the propeller torque in flying. You will have to twist the wing considerably more than \ in. because the paper will tend TOGETHER 4 PROPELLER CONSTRUCTION Fig. 5. Steps in making the propeller from two triangular shaped pieces of balsa wood. Q. | | — REAR FRONT WING CLIP ‘) WING cup _| bv Fog #11 MUS. W: METAL FITTINGS~% SIZE —_, 1s | | Fig. 6. How the “prop” shaft, bearing, ‘“‘cans,” S-hook, rear hook, and wing clips are made. nel and wrap the two together with soft twine with spiral turns about 1 in. apart. With the stick on a level surface and one of the 4-in. sides facing upward, brush paper cement or thick banana oil along the seam the full length. When this is dry, repeat the operation on the other side of the stick. Without twisting the stick, remove the twine wrapping and paint the seams again, but allow one side to dry before t-Smith (at the right) with his record model, which In the center is Maj. Gen. Mason M. Patrick. 81 STRIP CEMENTED ON WHILE CEMENTING SPAR CONSTRUCTION Fig. 7. Method of making the hollow spar of balsa wood and cementing on the cap piece. brushing the other. It is well to apply two more Coats in the same way, making thus four in all. As an added precaution, Shifler-Smith covered his spar with thin Japanese tissue paper cement- ed with thin banana oil. Each end of the spar is plugged with a piece of balsa about 5¢ in. long, cemented in place. The rear is left square but the front is ta- pered back from the bearing for about 1 in., as in Fig. 4. Cement on three “cans” (Fig. 6) made of No. 11 music wire. One can is placed at the center of the stick and the others at the quarter points, as shown in Fig. 4. One coat of cement is enough for the cans, so that if the rubbers should break in winding they will come off easily without damaging the hollow spar. Use three coats, however, to cement the bear- ing and rear hook in place. The horizontal stabilizer (Fig. 4) re- quires two crosspieces of bamboo, one 12 in. long and tapering’ from an oval cross section of 4% by 3@ in. at the center to lo by l% at the tip, and the other 8 in. long and of the same oval cross section at the center. These are fastened to the motor base on the top; that is, on the opposite side of the spar from the cans, the bearing, and the rear hook. The edging of the stabilizer is a silk thread. Use light Japanese tissue paper to cover the surface. It is well to fold the paper over the thread about \% or 3% in. If the thread is drawn in as shown, the paper will not sag or wrinkle badly. Treat the surface with light dope. The com- plete hollow spar should weigh almost exactly 1% oz. The detachable fin (Fig. 4) is triangular and made of bamboo splints cemented together. It has two bamboo prongs which fit into the rear end of tlie motor base; one of the prongs is merely an extension of the (Continued on page 124) METHOD OF HOLDING RIBS IN PLACE FOR CEMENTING CEMENT $ S.A L ¥ J .19 LI FASTENING HALVES TOGETHER. ” ATTACH CLIPS AFTER HALVES ARE JOINED REAR WING CLIP FRONT WING CLIP WING CONSTRUCTION Fig. 8. Fastening the wing ribs, joining the halves of the wings, and applying the clips.

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SuMNER Biossom, Editor Raymonp J. Brown, Managing Editor Artuur WakE.Linc, Home Workshop Editor Aurrep P. Lang, Technical Editor Epecar C. WHEELER, Associate Editor IsrAEL Dosxow, Art Editor Published Monthly by Popular Science Publishing Company, Inc., 250 Fourth Avenue, New York City. Single Copies Twenty- five Cents. In the United States andIts Possessions and in Canada, $2.50 the Year. In All Other Countries, $3.00 the Year. | For the Price of One Tube! _—. broadcasting is falling down on the job. We are bothered with interference and whistles, poor re- ception, inferior programs, and blatant advertising. The general impression is that interference and kin- dred troubles are necessary evils, eventually to be eliminated by new engineering developments. That is not so. There is no excuse for interference. Any competent radio engineer, work- ing with knowledge now available, could arrange the location and broadcasting power of a list of stations so as to supply every individual in the United States with a choice of from two to fifty stations, depending on the receiving equipment used. But petty politics, ignorance, sectional jealousies, and short- sighted trade rivalries block all attempts to solve the problem in any such common sense way. For the poor programs, marred by cheap advertising, we have only ourselves to blame. Broadcasting of the full scores of grand operas direct from the big opera houses, or entire plays and musical comedies from theaters, are entirely possible. But we have had to content ourselves with travesties on them by courtesy of Somebody-or-Other’s Hair Oil. We have paid for our broadcasting in an indirect and pre- sumably inexpensive way. Better programs would be avail- able if the great broadcasting companies were supported directly by the listeners, instead of indirectly by advertisers. This could be accomplished by a licensing system, the annual cost of which to each of the 25,000,000 or more set owners would be not more than the price of one radio vacuum tube! Get into Aviation! LSEWHERE in this issue, Larry Brent, a typical American young man of twenty-two, continues his vivid story of the course in flying he has taken as a prelude to a career as a professional aviator. No better proof that young Mr. Brent knows what he is about in selecting aviation for his life work could be supplied than a report just issued by Mr. R. L. Putman, a Chicago business man, of a year’s use of the airplane for business trips. Mr. Putman traveled 44,327 miles. It cost him $25,761, or about fifty-eight cents a mile—expensive traveling which, he says, was offset by the conveniences his airplane offered above those of more conventional means of transportation. The part of his report that concerns young Mr. Brent is the fact that almost half of what he spent went to his pilot and to the mechanics who serviced his plane. The pilot, during the POPULAR SCIENCE MONTHLY May, 1999 year, received about $8,000; servicing the plane cost about $4,000. While Mr. Putman’s expenditures on his plane show beyond doubt that the time has not yet arrived when airplanes are for the average man, the fact remains that the country every da is becoming more air-minded. There will be more Mr. Put mans to give $8,000 jobs to pilots and to pay generously mechanics who can keep their planes in running order. Probably no other career offers such glowing opportunities to young men who can qualify for it as does aviation today, Amazing New Roads Ahead N ONE week, recently, about as many automobiles came from American factories as were built in the whole year of 1909. One hundred and twenty-three thousand new cars began speeding up and down the highways. An interesting question is: How many automobiles will be in the world fifty years hence? How many billion machines will the earth support? Wider highways are coming; elevated roads and underground passages will help relieve traffic. But even so, the earth’s road room is limited. It is safe to say that when the limit is reached, airplanes, flying at different altitudes, will no more have exhausted the room in the sky than the ocean liners of today have congested traffic at sea. Meanwhile motor cars run by radio power are seen as an “almost certain” development of the twentieth century by G. M. Williams, president of a widely-known automobile con- cern. To start his car, the owner of such a machine would simply “pull a switch on the instrument board, thereby auto- matically tuning in on the wave which has been assigned to him.” And he would control the speed by turning a rheostat like the knob of a radio set. Engineers right now are at work on the problem, the solution of which will mean freedom from noxious fumes, the flexibility of electric motors— in short, motor cars the like of which the world has hardly imagined, Hobnobbing with the Martians ASSING interest has been aroused by an Englishman’s recent attempt to signal to Mars by radio from the power- ful Rugby station—an attempt foredoomed to failure. As Dr. J. H. Dellinger, chief engineer of the Federal Radio Commis- sion, explains, a layer of electrified air particles a hundred miles or so above the earth forms an impenetrable barrier to radio waves. But it is by no means inconceivable that, if there are human beings on Mars, we shall some day find a way to signal to them. Prof. A. M. Low, a leading British physicist, believes that if Martians have telescopes as powerful as our own they could see a smoke signal on our earth fourteen miles long and seven wide. Such a screen could be laid down by a fleet of airplanes. All this, of course, provided that there actually is life on Mars— a moot question to which science has not yet provided a satis- factory answer. They Are Saying— E DON’T know a millionth of one percent of anything.” —Thomas A. Edison. “There is no reason why we shouldn't have another glacial period.” —Dr. V. Nordmann, Danish geologist. “Lack of proper training during childhood and not lack of ability is responsible for most of the failures in life.’”-—Dr. Sanger Brown, II, New York psychiatrist. “Ships using airplanes can see further and shoot further and hit harder than any weapon known.’’—Rear Admiral W. A. Moffett. ‘ “If we are ever to fly as a nation, we must first fly as indi- viduals.’”-—Sherman M. Fairchild, airplane builder. “Unless active measures are taken to protect the forests of the United States, the country’s virgin timber may be exhausted within fifty years.”—Paul D. Kelleter, forestry expert. “A medical student with four years’ post-graduate study and two years’ hospital work commands less than a chauffeur, a broker’s clerk, or a floorwalker.’”’-—Dr. Hans Zinsser, bacteriolo- gist, Harvard Medical School. “The sun cannot be much-older than the earth.”—Prof. W. Nernst, German physicist. Fo

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an’s ver- nis- iles idio nan -m. uld ven es. —— Lis- May, 1929 POPULAR SCIENCE MONTHLY 83 For the Smoothest Ride over the Roughest Roads to Anywhere YEARS of Pionzrnine oo PIONEERS who blazed trails, harnessed streams, planned cities and linked them together with bands of steel rails, merely paved the way for scores of other pioneers, whose genius and fortitude have contributed a thousand devices for comfort, con- venience and easier living. Such a Pioneer was Maurice Houdaille. Houdaille’s 27 years of Pioneering devel- oped the Houdaille hydraulic double act- ing shock absorber, that made supreme riding comfort available for motor cars. Houdaille Pioneering had its effect in con- vincing the engineers of Lincoln, Pierce- Arrow, Cunningham, Stearns-Knight, Jordan, Ford, Nash Advanced Six, Chrysler Imperial, Studebaker President and Graham-Paige, to specify Houdailles as standard equipment on these cars. No manufac- turer, having adopted Houdailles as standard equipment, has ever given them up. If you are not enjoying supreme riding comfort in your car... drive around to a Houdaille Service Station or to your own car dealer, and have a set installed immediately. Houde Engineering Corporation BUFFALO, NEW YORK Prices $50, $75 and $100 plus installation. Slightly higher west of the Rockies and in Canada HOUDAILLE Hydraulic Double Acting SHOCK ABSORBERS |

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SS a ne Se

’ this bum gas at the Model Garage and, POPULAR SCIENCE MON'THLY May, 1929 When Valves Get Out of Step 2 Gus Tells a Stalled Motorist the Secret of Efficient Timing By MARTIN BUNN " HE gas is no good, that’s what's the matter,” growled the chubby man disgustedly as he banged down the hood of his car, stalled at the side of the road. “But Theodore,” quavered his wife, “the engine was running just a few min- utes ago. Why can’t you just run it far enough so we can get back to town?” “That, my dear Elvira, is precisely what Id like to know how to do. ‘You don’t suppose I’m staying here because of the beautiful scenery, do you? We got

Gus explains how the timing chain, a belt of metal links running on sprockets, makes the motor shaft turn the cam shaft, which operates the valves at exactly the right times. by jinks, 'm going to give ’em a ring and make ’em come and tow me in for nothing!” He stalked off down the road in search of a phone. Gus Wilson, veteran auto mechanic and half owner of the Model Garage, drove up in the service car a short time afterward. “Howdy, folks, sorry to see you’ve had trouble,” he called cheerily. ‘You ought to be sorry,” snapped the car owner. “It’s that bum gas you sold me. Motor won’t even run on it. Chugs once in a while when I step on the starter, but it hasn’t pep enough to keep on going.” “Try again and let me hear how it sounds,” Gus suggested. The starter spun the motor quite vig- orously but only an occasional weak ex- plosion followed. “That’s enough * said Gus. Quickly he maneuvered the service car around in front of the stalled automobile and hitched on the towing cable. “Now,” said Gus when they reached the Model Garage, “in the first place there’s nothing the matter with the gaso- line. We've never sold any bad gas, so that’s out. In the second place the trouble is in the motor. And in the third place it’s getting late. I'll drive you folks home; and tomorrow, Mr. Van Tine, you can drop around and I'll show you what happened to your motor.” HE rotund Mr. Van Tine was waiting when Gus arrived next morning. said Gus, “‘just as “‘Here’s your car,” we left it last night. To fix what’s the matter I’ve got to take off the radiator, . and while I’m doing that I'll explain about it.” “Sure it isn’t the gas?” questioned Van Tine, still a trifle skeptical. “‘ Absolutely,”’ Gus assured him. “‘The gas had nothing to do with your trouble. This car is several years old and the tim- ing chain is worn out. So are the sprock- ¥ ets. The timing chain, you know, is just a belt made of metal links, and it can wear out same as any other metal part that moves. The timing chain fits around the sprocket on the crank shaft of the motor and the larger sprocket on the cam shaft, so that when the motor shaft turns, the cam shaft operating the valves has to turn, too. “Of course, all cars don’t have timing chains. Some use gears to get the same result. What happened on this car was that the timing chain got so loose it began to jump teeth on the sprockets. Every time it jumped a tooth, the timing of the valves got later, until finally the valves were so far out of time that the motor wouldn’t run at all.” “You mean the valves don’t open to

Ask Gus—He Knows *<(-1 OMETIMES skidding is an S accident,”’ says Gus Wil- son, *“*but most.times the party behind the wheel is to blame. When the going is slip- pery watch out particularly for curves, especially if they are not banked. Do your slowing down real slow, which means don’t jam on the brake. “The first thing to do when you feel the back end of the car trying to get ahead of the front is to swing the front wheels in the direction in which you are skidding. If the back wheels, for instance, start to slew off to the right and you steer that way real quick and at the same time take your foot off the brake, ten to one you can pull right out of the skid. But Providence will have to be on your side if you steer the front wheels the wrong way, because you’re sure to do a right good imitation of atop!’

let the gas into the cylinders?” questioned. “Sure they open,”’ Gus asserted. “As long as the cam shaft keeps turning, the valves will open and close. But the point is that they open and close at the wrong time.” “No teamwork, eh?” *“*Exactly,”’ replied Gus as he removed the timing chain case and exposed chain and sprockets. “See how much play there is” he pointed out, as he wabbled the loose chain back and forth. ERTAINLY is loose,” Van Tine agreed. “I don’t see why it stayed on the sprockets at all.” “Lucky for you it didn’t come off,” said Gus. “Probably would’ve jammed and busted through the side of the case. Almost anything might have happened.” ““How’re you going to fix it?” asked Van Tine. “That depends on how long you expect to keep the car,’ Gus answered. “If you plan to sell it or trade it for a new model within a few months, perhaps I can take a link out of the chain. It seems loose enough for that. But if you want a real job the only way is to install a new chain and new sprockets. I could put in a new chain on these old sprockets, but it would wear kind of fast.” “‘T guess I won’t be buying a new car for a while,” said Van Tine. “Better make a good job of it and put in the new chain and sprockets. But tell me, how did you know the chain had slipped? I'd like to know how to spot the trouble, in case it happens again.” “You've got to know how a gasoline motor works before you can understand valve timing,” Gus replied. “Lots of people think that the valve just opens, the gas kind of rushes in of its own free will, the spark plug ignites it, and that’s all there is to it. They can’t seem to get it through their heads that each piston pushes-down on the crank shaft only on every other (Continued on page 164) Van Tine

| H

meee ey re

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. Tine “e As g, the point wrong 10ved chain play bbled Tine Layed off,” nmed ned.” isked pect f you 10del take loose ‘hain new ‘ould , car etter new how ped? ible, line tand s of , the will, ; all

re oen ee

POPULAR SCIENCE MONTHLY

Look for this mark oneveryRadiotrom WALTER E. HOLLAND CHIEF ENGINEER OF PHILCO Says:

a lisesi il *"No matter what care and skill a manufac- turer of radio sets may employ, the finest instrument that can be built is no better than its tubes. In the manufacture and testing of Phileo Neutrodyne Plus Receiv- ers. we use RCA Radiotrons, because they insure the fine reception of our sets.” Walt Z. ollnc All radio engineers agree that after a year of average use the vacuum tubes in a radio set should be replaced throughout with new ones. Old tubes left in mar the performance of the others. For finer results completely reequip your set with RCA Radiotrons. RCA RADIOTRON RADIO CORPORATION OF AMERICA «< New York < |Chicago ~ Atlanta ~ Dallas » San Francisco cineca Te anil

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we senenenetn-anesiadatatirees

How to Cast Concrete Seats By Making Two Simple Wooden Forms, You Can Turn Out a Number of Good Looking Garden Benches at Low Cost

By Leon H. Baxter Supervisor of Manual Arts, Western Reserve Academy, Hudson, Ohio TURDY garden seats can be made of concrete with but little equip- ment. Two forms made as shown in the illustration below will serve for making benches for the gardens of an entire neighborhood. A few alert boys working together can make seats for their own yards and sell others to friends and neighbors. As a matter of fact, many of these seats have been made in the course of their school work by boys and girls not more than twelve years old. The form for the top, or seat portion, is made from 1-in. stock, preferably pine; it should be about 22 in. wide and 4 ft. 10 in. long. As the seat is to be 3 in. thick, the edge pieces should be made 3 by 18 in. for the short sides and 3 in. by 4 ft. 8 in. for the long. Strips cut with a %-in. bevel—that is, triangular pieces—are mi- tered at the corners and nailed as shown to the sides but not to the bottom board. Make short cleats to hold the side- pieces in place and screw the sides to the ends with 14-No. 8 flathead screws. Two

POPULAR SCIENCE MONTHLY

pieces for suspending iron dowel pins in the cement are next made and placed in position as shown. Only one end form is necessary. The curved pieces are best sawed from blocks of pine 4 in. thick, 6 in. wide, and 154 in. long. The curves may be cut with a turn- ing or web saw, but for a very small expenditure this will be done at a wood- working mill or carpenter’s shop on the band saw. A top and bottom board are screwed on as shown, and well oiled wooden dowels are suspended from the top board (to leave holes in the cement for the iron pins which prevent the seat top from shifting). Apply linseed oil to all parts that come in contact with the cement mixture. Pre-

May, 19

Concrete garden Lenc..es of thi type are useful and ornamentg, pare reinforcing wire and rods as ind- cated for the seat top, and provide two 34 by 14% in. iron rods and sufficient wire mesh to reinforce each of the seat supports. The mesh, or hardware cloth as it is preferably called, should extend to within about 1 in. of the edges all around. Mix thoroughly one part cement and two parts dry, clean, sharp sand. Cup this up cone shape with a square-nosed shovel and scoop out the center, into which pour enough water to fill the hol- low three quarters full. Scrape the sides of the cone into the hollow evenly all around and add enough water to make a quaky mixture. Take four times as much gravel—run- ning from 34 to 1% in. in diameter—as the amount of cement originally used. Wet the gravel thoroughly

and work it into the cement and sand mixture. Have the final mixture still of a quaky consist- ency. Place the mixture evenly in the forms, working it into corners with a trowel. See that all air pockets are broken up. Allow the concrete to set for half an hour; then smooth the surface lightly with a trowel.

==> The casting will harden over-

night but should remain in the

form about three days. Sprinkling

it daily will insure its drying

RODS 3% x52"* ‘> cones fps asses wr mrrre sae Stites Lanpeereee | ————— je 61 TT = —-—— .---— “DOWEL ROD HOLES EDGE VIEW % CHAMFER FINISHED SEAT TOP aa . % ei Sortom B BOARD = en TRIANGULAR STRIPS ¥, MESH NETTING SAME SIZE) ete a Cap ee See tee ee FORM FOR SEAT TOP FORMS PUT TOGETHER WITH 1%-%6

ALL FLATHEAD SCREWS. How forms are constructed of wood for making the reinforced concrete slab for the seat top and the two ornamental supports. INSIDE OF FORMS TO BE OILED.

e's "REINFORCED: "8 CONC Se, Rae SPORT. Ae. on es Hick out evenly. To improve the surface and conceal any slight air pockets and roughnesses, apply with a 2-in. paint brush a mixture of one part cement to one part sand. A still more even, smooth surface may be obtained by rubbing the concrete with a carborundum stone or a <wN a

common brick dipped in cement

and water. (Continued on page 118)

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'S Of this lamental, iS indi. de two fficient he seat e cloth extend ges all nt and . Cup -nosed *, into 1e hol- 2 sides ly all 1ake a —run- oT—as inally ughly t and final nsist- in the rners ll air w the hour; ghtly over- | the kling ‘ying and and 2-in. part still y be rete or a ent 118) UNDER THE PAINT LAY RICHES: WITH what ghoulish glee have count- less collectors, amateur and profes- sional, scraped the paint from an old table or chair to find the cherished beauty of walnut or cherry underneath! Wood is as beautiful today as it was when antiques were being made. The lowly pine and birch of grandfather’s day have come even further into their own under the skillful hands of men who know how to bring out their real beauty. With the skill which Johnson’s Wood Dye puts into even the most amateur of hands, there need be no resortto opaque finishes . . . makeshift substitutes for lack of skill in finishing. Without JOHNSON’S woOoD DYE 9O00006000006SSSSSSSSSSSSSSSSSSSSSHSSSSSOSSSSOSOP SOOO ODO OOOO PO OOD POPULAR SCIENCE MONTHLY And ....- streaks, without laps, the Dye sinks deeply, revealing the full depth and texture of the grain. There is no pig- ment in Johnson’s Wood Dyes (spirit | and oil). There is therefore no dirty scum left behind when it is used. It dries quickly and smudge-proof. The subtlest gradations in color, from the darkest to the lightest shades, are avail- able in Johnson Wood Dye. ° Our valuable instruction , sheets on expert wood finish- ing methods are yours for the asking. Just mail the coupon. S. C. JOHNSON & SON “The Interior Finishing Authorities” Racine, Wisconsin SPOSSSSSSSSSSSSSSSSSOSSUSOSOSOOSOSD S. C. JOHNSON & SON, Dept. (PSM 5), Racine, Wisconsin Gentlemen: Please send me your free color chart and instruction sheets on expert wood finishing methods.

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HE ignition system of most cars is so timed that when the spark lever is in full retard position, the spark will occur at top'dead center. It is, however, not easy to know just when the breaker points actually part company and eause the spark. You can determine exactly when this happens by the aid of a small mirror. Set it where it will reflect the face of-the am- meter, as in Fig. 1, while you turn the hand crank. When the points break and the spark occurs, the ammeter needle will flip back to zero. You can use this test to check the ignition timing, in which case turn the crank until the needle flips back and then see if the piston is at the top; or to make sure that the piston in any cylin- der is at the proper point for setting clearance of the valves. When the spark oc- curs, both exhaust and in- take valves are, of course, closed. BATTERY STOP LIGHT An Automatic Light °“"™ TO NEED to fish around in the dark trying to find something in the luggage compart- ment. You can easily arrange an auto- matic light which will go on when the trapdoor is lifted, and go out when you close it, as in Fig. 2. A socket of the bayo- net type to hold a headlight bulb is attached underneath the front edge of the door opening, and a stop-light switch is attached at a point where it can be con- nected by means of a chain to the hinge or to a screw eye in the door. The chain should be adjusted with enough slack so that when the door is in a fully opened position, the switch will be thrown on. Run a wire from the un- grounded battery terminal to one terminal of the socket, connect the other terminal of the socket to one terminal of the stop-light switch, and ground the other terminal of the switch to the Fig. 2. Automatic light for luggage compartment goes on when lid is up. ‘ Small vi nearest int on oe pen De Hed the metal frame of spring compressing tool. the car. Fig. 1. POPULAR SCIENCE MONTHLY oF, SEEING AMMETE IN MIRROR Th TURNING OVER THE MOTOR WITH CRANK By watching the ammeter needle in a mirror, as shown, you can see when spark occurs and check the timing. COTTER PIN (Meemncma ericson SCREW DRIVER FEELER GAGE Fig. 3. Timesaving tool for ad- justing overhead valves fitted with slotted bolt and lock nut. Ten Dollars for an Idea! H. T. Goshon, of Pasadena, Calif., wins this month’s $10 prize for his suggestion of a valve adjusting tool, shown in Fig. 3. Each month POPULAR SCIENCE MONTHLY awards $10, in addition to regular space rates, for the best idea sent in for motorists. Other contribu- tions that are published are paid for at the usual rates. Valve Adjusting Tool IGURE 3 shows a homemade tool that will be a timesaver for either the garage mechanic or the motorist who does his own repairing in adjusting over- head valves that are fitted with a slotted bolt and a lock nut. Its advantage is that you do not have to remove the screw driver from the slot each time you test the clearance between the valve stem and the end of the rocker arm. The spring holds it securely in the slot. To make this tool, take an end wrench that fits the lock nut. Bend a piece of Ingenious Ideas for Motorists St How to Check Ignition Timing—An Automatic Light for Luggage Compartments—Timesaving Tools You Can Make three-sixteenth-inch cold rolled stock inty form, as shown, and bolt the end to the end wrench after drilling a hole for the screw driver bit. A cotter pin, a washer, and a spring complete the assembly. To use the tool, fit the wrench over the lock nut while pulling the screw driver bit up against the spring Let the screw driver edge drop into the slot, loosen the lock nut, test the clearance while still holding the wrench in place, turn screw driver to change clearance, and when you have it right hold screw driver in the correct position with one hand while you tighten the lock nut with the other. This tool has saved much time in the repairing of cars with overhead-valve motors. Spring Compressor rr. YOU have no spring compressing tool and you wish to remove the retaining pin that fits through a slot in the overhead type of valve spring, you can use a pair of end cutting pliers, as shown in Fig. 4. Into holes drilled in a small piece of wood, set the handle ends of the pliers just far enough apart so that the jaws will clear the valve stem. All that is necessary then is to press down on the wooden handle and remove the pin Grip a leg of the pliers between the thumb and first finger while you are pressing down to avoid pinching your finger if the pliers slip sidewise. A Simple Hood Protector HILE gasoline has practically no effect on the lacquers used on mod- ern automobiles, it does leave marks which must be polished off. If your car is fitted with a gasoline tank under the cowl, you can avoid spotting by making a protector as shown in Fig. 5. The hole in the protector should fit tightly around the filler opening. RUBBERIZED gs ILLING OSE 15% 24" PROTECTER Fig. 5. How to protect automobile finish from gasoline stains when the tank is under the cowl ae | C Ic Yo Th TL In spi against statem For that u: youre power labora highe

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AY, 1999 May, 1929 POPULAR SCIENCE MONTHLY t|Suppose somebody said — Ck into to the for the vasher, te the it “f k nut driver spring. en the arance. rrench ver to

when screw sition ; you h the much cars otors. Sor pring you ini r: valve ir of 10Wn rilled , set liers jaws it is the pin. umb sing r if

no od- irks the ing ole ind

“I can add 10% to 30% more power to your engine. I can preserve its first-year feel for 30,000 miles.

a

99

——— =i i —- You’d want to know how and why. the New Mobiloil. The “how” is The “why” is In spite ‘of our scientific prejudice against superlative language, we are prepared to make some very strong statements about the New Mobiloil. For example: We are willing to say that use of the New Mobiloil will help your engine develop 10% to 30% more power than other oils generally sold Our road and laboratory tests have bettered the higher figure. for the same motor. Our assurance that the amazing New Mobiloil will stand up better and consume more slowly under high speed is a conservative reflection of the speed-test records made in thousands of miles of running at the Atlantic City Speedway. And it is an establish- ed engineering fact that the oil which lasts longest and stands up best at high the New ad told below. speed, lubricates best at any speed. We believe that, with regular drain- ing and refilling, and with reasonable care of your car, the New Mobiloil will keep the first-year feel in your new engine for at least 30,000 miles. Actu- ally, Mobiloil has preserved the first- year feel in many engines for more than twice this distance. The New Mobiloil will give you many thousands of miles of the pleas- antest motoring you have ever known and save you many repair bills besides. Mobiloil has been the World’s Quality Oil ever since it lubricated the first successful motor car. Mobiloil is made by the Oldest and Largest Specialists in Lubrication. VACUUM OIL COMPANY Makers of high quality lubricants for all types of machinery i Mobiloil

Make this chart your guide It shows the correct grade of Gargoyle Mobiloil for certain prominent cars. If your car is not listed below, see complete Mobiloil Chart at your Mobiloil dealer's.

1929 1928 1927 1926 NAMES OF Engine Engine Engine Engine PASSENGER = ray roy CARS e/s|/el]s]e1si]e] s E & E A | EI Ss € A} AI|EIALFE [AILS IAS Auburn, 6-66...... ry ee AO FY. Ae PE ie A - Seer BB | Arc.| BB | Arc.| BB | Arc.| A | Arc. “ other models | A | Arc.| A | Are. rs Arce.| A A A Eee BB | Arc.| BB | Arc.| BB | Arc.| A_ | Arc. SIS ss cienadnns BB | Arc.| BB | Arc.} BB | Arc.} BB | Arc. Chandler S t oe eee ee Se fe ae tae eee r models | A |Arc.| A |Are.}| A |Arc.} A | Arc. Chovedlet........2 . | A |Are.] A | Are] A | Arc.| A | Arc. Chrysler, 4-cyl...... soso foeee) A | Asc.| A [Arc.| A | Asc. “Imperial... | BB | Arc.] BB | Arc.) A | A} A | A “other models | A | Arc.| A | Arc.] A AIA A TS BRON 65.5. <is100< BR (Ribescs tices ee IS Were Dodge Brothers..... | A | Arc.}] A | Arc.}] A | Arc.| A | Arc. PIES dois ausa:scic ax A |Arce.| A | Are. ee at — kup aeeseece A |Ase.] A | Asc.] A | Ase.}....].... REPRO A |Are.| A |Arc.]| A | Arc.| A | Arc. Ford, Model A..... A |Arc.| A | Are. RP Re ET “ ni—g hadpatense theses ae EJ E E Beanie. io6.s0655 BB | Arc.| BB | Arc.| BB | BB} BB | BB Gardner, 8-cyl...... .| BB | Arc.| BB | Arc.| BB | Arc.]| A | Arc. et eee pee PR me ee Graham-Paige...... BB | Asc. BB | Asc.}.... |... -Jocee] ose udson..........: | A | Are.}| A | Are.] A | Are.}] A | Are. Hupmobile........ BB | Arc.| BB | Arc.| A | Arc.| A | Arc. OS, Sern BB | Arc.} BB | Arc.| BB | Arc.}....]..-- Meher mod A |Arc.| A |Arc.] A | Are.]....].... other models ...-|BB] AJ A}]ATAIA baentueieas Are.| A |Arc.| A |Arc.| A | Arc. Nach, Adv. & Sp. 6. | BB | Arc.} BB | Arc.} BB | Arc.| A | Arc. r models | A | Arc.] A |Are.] A | Arc.] A | Arc. Ae A |Arc.}| A |Arc.] A | Are.| A | Arc. OS eee A |Arc.| A |Arce.] A |Arc.}| A | Are. Peerless, 72,90,91... | BB| A | BB) A] BB} A | BB; A other models | A |Arc.| A |Arc.] A | Arc.| A | Arc. Pigmeuthh. «..0.0005 Pe. ery Pere, ees ce Pye Pere agg Fe ee A |Arc.| A |Arc.] A |Arc.| A | Are. PRE Ie A |Arc.| A |Arc.| A | Arc.} A | Arc. Stare Knight, 60 BB | Asc.| BB | Asc.) .... 1... -Besestee-e models | BB | A | BB} A | BB} A | BB] A sane Reugaben Arc.| A |Arce.| A |Arc.] A | Are. SE eee be oe ff) a ee eee eee ” redetds. A |Are.] A |Arc.] A |Arc.] A | Are.

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Varnishin By F. N. VANDERWALKER, Author of House Painting Methods TAIN and varnish form a popular and satisfactory finish for front doors, provided a high-grade exte- rior varnish is used and the work is properly done. When a door to be refinished is in very bad shape, the old finish should be re- moved to the bare wood. The refinishing process then is similar to finishing a new door. If the old finish is in reasonably good condition, it is sufficient to clean and sandpaper it thoroughly and apply two coats of spar varnish. For removing the old finish, when nec- essary, the amateur painter will find it best to use a commercial paint and var- nish remover applied according to the manufacturer's directions. When prop- erly softened, the varnish can be cleaned off with rags or waste and a dull scraper or broad putty knife. The scraping must be done with care to avoid splintering or damaging the wood. Move the scraper with the grain of the wood and be particularly careful to clean out the corners. Coarse steel wool may be used on panel moldings and irregular surfaces, Wash away all traces of the varnish remover with benzine or gasoline, and sandpaper with the grain, using No. 1 sandpaper, until the wood is smooth and clean looking. Then dust it well. Once the door is in condition to be re- finished, you have a choice of finishes. Personal preference or the architectural style of the house may call for a finish that is well filled, smooth, and glossy; or it may require an antique or weathered appearance. It is most convenient, per- haps, to classify the finishes in respect to the woods of which doors are commonly constructed. Doors of pine and fir frequently are fin- A blowtorch is used in giving cypress this strik- ing driftwood finish, known as Japanese sugi. POPULAR SCIENCE MONTHLY x Your Front Door What Preparations to Make and Materials to Use — Removing Old Finishes—Stains and Their Application Front door of a modern Spanish style home. It is finished with stain and varnish to reveal the decorative grain of the wood. ished with paint, enamel, or lacquer enamel. Such finishes were described in an article, “How to Enamel a Front Door,” in the August, 1928, issue of PopuLAR ScreENcE MonruLy. When, however, they are to be var- nished, the following procedure will insure good results. The most generally used and most practical stains for new doors are ready-mixed oil stains (or wood dyes, as sometimes designated). On old doors, from which the original finish has been re- moved, alcohol or spirit dyes are fre- quently preferred because of their supe- rior penetrating qualities, but they must be of a type suitable for outdoor use so that they will not quickly fade. Provided the wood has been well sand- papered and dusted, apply the desired stain with a 2-, 3-, or 4-in. flat paint or varnish brush. Work it well into any grooves and joints and brush it with the grain of the wood. If an oil stain is used, allow it to set for a few minutes and then wipe it lightly and evenly to remove any excess on the surface. The color may be lightened to some extent by vigorous wiping. Should the color be too light, apply a second coat of stain. Allow the stain to dry thoroughly; overnight is usually sufficient. May, 19% For the varnishing, use only exterior varnishes made for such service. They are usually called spar varnishes. Some jp. terior varnishes, however, are also called spar, although they are not suitable for outside wear. Apply the varnish with q flat varnish brush 2 or $ jn, wide. Brush it well into the wood, applying it freely, but avoid sags, runs, or wrinkles, Runs are likely to occur around moldings, under openings, and at corners. After applying the varnish to one side of the door or as large a part as is conven. ient, wipe the brush on the pot edge to remove all the varnish possible and again brush over the surface, first in one direction — Using a wad of excelsior to wipe surplus paste filler from the surface of an open-grained wood. and then at right angles, so as to pick up any excess varnish and distribute the coating evenly. Allow at least twenty-four hours for the varnish to dry; then rub it down lightly and evenly with very fine waterproof sandpaper and water or with pumice stone and water on a felt pad. Rub only enough to cut off the dirt nibs and dust. Wash the surface clean with water and wipe it dry. Apply the second coat in the same way and rub it preparatory to a third coat, if a third coat is necessary. A third coat should be used when a new door is being finished or an old door is being refinished from the bare wood, but two coats are sufficient to renew a varnish finish that was in fairly good condition to begin with. The final coat should not be rubbed unless you wish to have a semidull finish. Obviously, the (Continued on page 117)

Page 87

TAY, 1999 OT IS€ Only de for Usually ome jn. yer, are gh they Outside with a t 3 in, ito the y, but "inkles, around 38, and ing the door onven- he pot arnish h over | ection pick » the r the htly roof tone yugh Vash De it way oat, Poat ing hed are hat gin ish. 17) May, 1929 C&L 32 It is more expensive his daily bus’ but rugged ab red Ther YOU ABOUT “You bet your life I am,” you say. “When I buy a tool it’s got to be right and it’s got to stay right.” When you buy a Clayton & Lambert torch you’re putting a worth-while tool on your work- bench. The most exacting blow- torch uses are considered in the manufacture of Clayton & Lamberts. Lasting materials—the strongest avail- able, selected for long, efficient use. Many of the features of design are ex- clusive and patented Clayton & Lam- bert improvements—the result of 40 years’ experiment and invention. And Clayton & Lambert torches are made by precision workmen. Men who think of tools and look at tools in the same light as you. For instance—the vaporizing cham- ber has an exclusive vein system for quicker, hotter heat. That makes the torch function better and saves money r st popular blow-torches we have ever made. is one of the me ie the ng oe it is ~—_ for much . It is designed for the man who uses a blow-torch in ’ harder nS4 iness and demands not only excellent performance ility to stand rough handling. 32 contains the most ed patented C&L blow-torch improvements. It also has a advance fandle with the gold stripe. Sure sign of satisfaction. PARTICULAR YOUR TOOLS? POPULAR SCIENCE MONTHLY grolECTigg This blow-torch is especially made and priced for the man who likes to do odd jobs around the house, or to tinker with mechanical things. It will last a lifetime if it is not abused. The usual retail price is about five dollars. Most hardware, elec- trical and automobile accessory stores have it—or can get it for you quickly. Look for the red fiandle with the gold stripe. Detroit, Mich. 91 on your fuel bills. All fittings are built into the tank by a patented method that prevents their fall- ing in or coming out. There’s absolutely no danger of an explosion with a Clayton & Lambert torch. Even the most delicate part—the gas orifice—is fool-proof. In the No. 158 the ori- fice has a guard. Slightly higher priced, No. 32 has a patented de- sign so that you'll never ruin the torch by a careless twist of your wrist. And as you close the valve you automatically clean the orifice. Things of that sort have made Clayton & Lamberts the largest selling torches in the world. There’s satisfaction and pleasure in work- ing with such a fine, capable tool. You can buy Clayton & Lambert torches at hardware, electrical and automobile accessory stores. Look for the handle—it’s red with a gold stripe. But to be sure—look for the trade-mark, too. It pays you to be certain that you’re getting a Clayton & Lambert. CLAYTON & LAMBERT MANUFACTURING COMPANY © This seal on an advertisement in. POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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92 POPULAR SCIENCE MONTHLY A Dresser for Small Home; Requires Little Space, Is Not Hard to Build, and Has the Style and Grace of a Fine Old Antique By Wiituram W. KLeNKE OUND, knotty white pine should be used in making a small Welsh dresser like that illustrated so that it will be in strict keeping with original antiques of this type, which are highly prized and valuable. In finishing the dresser an attempt should be made to imitate the mel- low tones of fine old pine furniture. This can best be done by applying one coat of boiled linseed oil fol- lowed by a coat of one part walnut oil stain to five parts turpentine. Allow the stain to dry thoroughly and then rub the high parts with fine sandpaper until the wood is almost bare, so as to give the piece a worn effect at those places where wear would naturally become vis- ible in the course of years. Follow this treatment with two thin coats of white shellac and a well-rubbed coat of furniture or floor wax. All the applied moldings shown in the drawings below are of stock de- sign and can be obtained in most localities, although it is possible to substitute other stock moldings in their places. The drawer pulls should have the finish of dull, antique brass. The dresser is made in two separate units which, when completed, are screwed together. The instructions for construct- ing the two parts may be summarized briefly. Body or base unit. Turn the four legs carefully to the design indicated. Work *) | so i r= i | — As GF ; iE - rTM oN TOP to} 2U ' GZ .- s BEAD Z 7 Tv ra : Oe oe b= § Dano 1 toh & : JOINT = he ior i = arr) > fe SCREW | TOGETHER 4 y | . BI OOVETAIL tal : prawer \QGRLY | iE = By g 7 'y f . ae Sa n> 2 at ze oe = au 4— er 3, es. Et 344-354 . MORTISE @ TENON | : a OR DOWEL JOINT /\ ° H me st oe . 5 ed e O a - _ = + T y an _— ay 4 Bean . kK ‘SECTIONAL ( ‘ FRONT VIEW tt DETAILS & SIDE VIEW & Front and side views of the small Welsh dresser, and details of the moldings. The upper and lower sections are assembled separately. This dresser won first prize in one division of a contest conducted by Poputar Science Montucy for teachers. out the rails to the desired profile and hand dress them thoroughly. joints and assemble the frame. The bot- tom shelf must be built in at the same time the project is being glued together. Construct the drawer and put it in place. Work out the top and fasten it to the frame from the underside by using May, 18 = May, 1 To panel irons or similar fastenings thy will allow for expansion and contr, tion. Apply all moldings. Shelf unit. Hand dress all th, stock. Cut out the profiles of the sides and the toppiece. Cut dad joints in the sides. Carefully fit th shelf, the top, and bottom, and x semble the whole. Fasten the bag, in place by nailing through into th shelf and the top and bottom pieo Apply the top molding. Screw th shelf part to the body part from th underside. Fit and fasten th molding at the junction of the ty units. Clean all parts thoro with sandpaper and finish as pr, viously suggested. A Lacquered Finish EN a lacquered finish is & sired instead of shellac ap wax, the following method may substituted. Give the wood an antique appew. ance with greatly thinned brown oa alcohol wood dye or a stain made by dissolving eight tablespoonfuls of ai. ia drying asphaltum varnish in a quart of gasoline. Allow this to dry thor $ oughly and apply a coat of one pat orange-shellac and one part denat ured alcohol. Smooth this, when dry, with the finest obtainable sandpape and rub through the stain to form “hig lights” as described by Mr. Klenke. Dut well and apply another coat of thm parts orange shellac to one part alcohal Cut all Finish with two coats of clear lacque Hi and rub the second with FF pumice: mee and crude oil. Finally polish the piece. ete. stroke takes ae eS eel el 8", 5 For his Welsh dresser design, Mr.Klenke was awarded first prize in the advanced woodworking division of a shop problem competition recently conducted by the Educational Department of POPULAR SCIENCE MONTHLY for teachers. The list of prize winners is as follows: Woodworking. Elementary: 1—F. W. Megow, Wyncote, Pa.; 2—George Dally, Milwaukee, Wis.; 3—W. A. De Vette, Erie, Pa. Intermediate: 1—Jonathan Bright, Erie, Pa.; 2—Charles A. Sylvester, Pittsburgh, Pa.; 3— George Dally. Advanced: 1—William W. Klenke, Newark, N. J.; 2—Frederick W. Voss, Waukegan, III.; 3—Paul N. Wenger, Greenwich, Conn. For Metalworking. Elementary: 1—W. A. DeVette; 2— For g Jerome F. Derwallis, Newport, R. I.; 3—E. W. Manzer, Pde Bronxville, N. Y. Advanced: 1—George Gordon, Jr., in a “an Bridgeport, Conn.; 2—Clyde R. Garl, Canton, Ohio; 3—E. C. Youngbluth and John F. Faber, Erie, Pa. Electricity. 1—S. L. Coover, Beaver Falls, Pa.; 2—E. A. Rerucha, Wakefield, Mich.; 3—G. Dewey Fenster- macher, Allentown, Pa. Many of the designs will appear in forthcoming issues. |

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Tay, 19% Cs ings that COntrae, alll th May, 1929 POPULAR SCIENCE MONTHLY ISSTON files were made first for Disston saw makers. These men must have files that cut fast, cut true, save time and stand up to the job. Files that are sharp! . . . accurate! . .. dependable! . . . lasting! These are the qualities that Disston Steel makes possible in a How to File Your Hand Saws Told by Saw Makers Who Are the World’s Largest Users of Files Now, for the benefit of all who work with tools, Disston Files—for every purpose—all made from Disston Steel, may be had at good hardware stores. Ask for “Disston”! Saws, of course; but also file and in all cutting tools. Files for the Metal Worker Every kind, size and style. A Disston 8-inch Mill File, bastard cut, is fine for sharpenin axes, lawn mowers, garden tools, and genera work in the home and shop. Excellent .for finishing metal surfaces. 25 cents each. Hints on Using a Hack Saw For cutting pipes, bolts, nails, curtain rods, etc. Strain blade tight. Cut on forward stroke. Disston No. 3614 Hack Saw Frame takes 8” to 12” blades. $2.10. Blades, 8”, 55c doz.; 10”, 65c doz.; 12”, 75c doz. For Finishing Wood Surfaces For giving a fine finish to your work, remov- ing paint, etc., use a Disston Acme Cabinet § r, made of Disston Saw Steel. Made in al needed sizes, 244” and 27%” wide and 5” and 6” long being standard. 25c and up. Every saw user will enjoy reading “The Disston Saw, Tool and File Book,” an illustrated manual on the selection, care, and use Disston Files. MATEUR mechanics realize that good work requires keeping good tools in perfect condition. “The Disston Saw, Tool and File Book” tells and shows you how to sharpen your hand saws. It answers’ these questions, so frequently asked: What tools do I need for filing a hand saw? A saw file, with handle. The Disston Special Extra-Slim Blunt Saw File is easiest to use. A saw clamp is necessary. The Disston D-3 Filing Guide and Clamp will greatly assist you in filing your saws. If the teeth require setting, use a Disston Triumph Saw Set. W hat is meant by “jointing” a saw? Jointing is leveling the tops of the teeth before filing. Necessary only when teeth are uneven or out of shape, when they should be evened up on top with a Disston mill file or a Disston Hand Saw Jointer, before setting or filing. How are the teeth to be filed? Look at a new saw, or at perfect, sharp teeth at wide end of your saw, if it has never been sharpened. Follow these perfect teeth for shape and bevel. On cross-cut saws, start at small end of blade and work toward handle. File every other tooth, then reverse saw and file remaining teeth. Hold file level, at 45° angle to blade. On rip saws, file teeth straight across. All your saw filing questions are answered in “The Disston Saw, Tool and File Book.” Write to us for it. DISSTON Makers of “THE SAW MOST CARPENTERS USE” Ss of tools. It tells how to file and set saws and contains much other helpful information. Sent free. Use the coupon, or write for it. © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. Henry Disston & Sons, Inc., Philadelphia, U.S.A. (In Canada, address Henry Disston & Sons, Ltd., Toronto) Please send me “The Disston Saw, Tool and File Book.” Name and Addressz....................-+- “The Saw Most Carpenters Use” The two handiest saws for the home work- shop are the 26-inch 8-point for cross-cutting, and the 26-inch 514-point for ripping. You will need these on almost every Sys The popular “D-8” Lightweights cost $3.45. Handiest of All Small Saws The Back Saw, with fine teeth and stiff ee | enables you to do smooth, accurate cutting ol mitres, parm, etc., for making furniture, picture frames, etc. Disston No. 4, 12” size, $” under back, 14-point, costs $3.00, On Your Power Saw Outfit With a Disston Circular Saw you can do better work. Disston Steel and Temper make a saw cut easier and stay sharp longer. Th is a Disston Saw—cross-cut, rip or combina- tion—for your outfit. Made in all sizes.

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he “Ten 5 EASURING tools manu- factured today combine precision and durability - to a remarkable degree. Modern mechanics work to limits of accuracy that a generation ago would have been considered so close as to be of service only in the finest of scientific work. While the instruments with which the present-day machinist measures his work are constructed with a precision that makes it possible to measure almost infinitesimal differ- ences in length, there are so many factors that influence this result that the mere use of a precision tool does not necessarily mean that the work will be just that precise. Figure 1 shows what startling differences are made by variation in temperature. A toolmaker de- cides he will check his vernier micrometer with a standard pre- cision gage block, of the kind that has been standardized by the Bu- reau of Standards by the light wave method and which can be depended upon to be accurate. The tool room from which he obtained the gage block was a little cold that morning, and the gage block is at a temperature of 60° F. He has been carrying the micrometer in ‘ his vest pocket, and it is at a temperature of 80° F. Now the gage block was stand- ardized at 66° F., as are all others, and at Mishaps which may throw anvil and spindle out of parallel; how to test their parallelism. POPULAR SCIENCE MONTHLY Thousandth” Touch How a Machinist Can Insure Great Accuracy in Using His Micrometers—Methods of Testing Them— Vernier Calipers By HENRY SIMON FIG. 1 ‘} BLOCK SHORTENED 00003" I] FRAME LENGTHENED 00007" ERROR IN READING .0001"_ May, 19% may read zero when it is closed and 1.0000 in. when tested with a 1p, standard, and yet be inaccurate g some of the intermediate points The nut makes contact with th spindle for about only one fourth of B Diagrams to illustrate why micrometers require care- ful testing with gage blocks. that temperature would be precisely 34 in. long. However, the gage is 6° cooler than standard, and, as steel changes in length .000007 in. per inch length for each change of 1° F., the gage block is .00003 in. short. In like manner, the mictometer, which is 14° warmer than standard, has increased in length .00007 in. This, added to the shortening of the gage block, makes .0001 in., which can be read with the vernier. Therefore, if the tool were checked under the conditions named, it might be said that it were one ten thousandth off when, in reality, it was absolutely correct. If you want to deal in ten thousandths —and that is the reason for the vernier on your micrometer—the way to be sure that it is “right to the scratch” is to check your micrometer periodically by compari- son with unquestionable standards. These are available in the shape of precision size blocks, which are guaranteed accurate within less than .00001 in. If your shop does not have a set, you may be able to obtain the use of a set owned by someone else. However, you should bear in mind that your micrometer and the gage blocks must be at the same temperature. Figure 2 shows why a good micrometer MICROMETER N? 10. 12. 28 its length. For this reason it is wig to check the micrometer at inte. vals, as shown at 4A, Fig. 3, an note down what differences ap observed on a card to be kept fo reference, as at B. This checking should be done with standard blocks, and it is well to check one or two of the intermedia: numbers on the barrel, say 8 and 16, One other formality should bk attended to, or else the conditiog shown in Fig. 4 may exist. Her the same micrometer is giving differ. ent readings on three objects, each of which is exactly the same size, The flat end gage at B is measured exact size, the round disk at C is read undersize, while at A a thin piece of work, a narrow-faced part, is measured still more undersize, The reason is that the end of the spindle and the anvil are not paralle, as shown in Fig. 5 at D and E. There are various ways in which the face of the anvil may get out of parallel with the spindle—ways other than that practiced by the imaginative garage man who dis covered his “mike” was also a good C-clamp. It may become peened by an accidental blow, as in Fig. 6 at A, or from local pressure from being clamped tootight- ly in a vise as at B; or it may have been accidently overheated as at C. Likewise, the spindle may have become sprung 3 trifling amount as at D, yet enough to cause trouble. (Continued on page 115) Testing the truth of a micrometer spindle; points to observe in checking vernier calipers. May, } ’

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LY, 199) PWise, ing 4 e 115) =) May, 1929 POPULAR SCIENCE MONTHLY 95 | 4 ey need Starrett ACCURACY and DEPENDABILITY coo The same quality of materials and workmanship that has made Starrett Tools the universal choice of expert machinists and carpenters has made Starrett Tapes and Transits and Levels [30'stcti'Fape ms i‘ a a equally popular favorites. coset Wet ‘made, strong, surprisingly low in price. Your tool dealer has a Starrett Tape, Transit or Level that meets your exact requirements. Ask to see them. Let us send you a free copy of Starrett Catalog No. 24 “WwW”. THE L. S. STARRETT CO. World’s Greatest Toolmakers Manufacturers of Hacksaws Unexcelled Steel Tapes—Standard for Accuracy ATHOL, MASS., U.S.A. Wood leveling rod and target. This chap is using a Starrett No. 99F Transit, Cieza J an exceedingly simple, practical transit anyone Starrett No. 132 Bench Level with. can use at a very moderate price. Double Plumbs.

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Hints for “- = 90 Ye DRILL AND COUNTERSINK ¢. GRIND 7 £ 7 GRIND Ye DRILL AND ay FRONT VIEW EDGE PERSPECTIVE vViEw 6 pri. Ye veer (Two HOLES) 7 GRIND —*%r- i EDGE FRONT VIEW Fig. 1. Spiders for use instead of common parallels in three and four-jaw lathe chucks. NSTEAD of using loose parallels for setting up work in the lathe chuck or on the faceplate, the writer prefers to use spiders such as are illustrated in Fig. 1. Their advantage is that they will stay in place and cannot slip out should the clamps become loosened. The spiders are made of machine steel, casehardened and ground. The holes in the center are for clearing any projection there might be at the center of the work; the other holes are drilled for the sake of lightness. A set should be made for use in three- jawed chucks and another for four-jawed a 4p RAD. = moe 56 DIA. Met) sieeve Fig. 2. How to provide a small arbor with a square shoulder without danger of its breaking. 125 DIA> kart SLEEVE chucks. Convenient heights are 1 and 1% in.—Georee A. McCuttey. VERY tool-room man knows how ex- asperating it is to make up a small arbor of the type that must have a square corner at the shoulder and then have it break at that corner. Such things are often required for turning or grinding operations on small bushings. Figure 2 shows a method of making this kind of arbor with less chance of break- oe. The shoulder itself is generously eted, and a bushing is pressed up against it to obtain the truly square cor- ner.—H. J. CHAMBERLAND. POPULAR SCIENCE MONTHLY the Alert Shopman Old Bill Says— AFETY must be made a habit. As long as safety rules remain merely rules, they can- not accomplish the greatest good Be continually on the alert for methods to improve the quality of your work. Give the same care to the dial indicator that you give to your watch. Milling cutters can be run much faster than lathe and planer tools because only a small part of the cutter is working at a time. High-speed steel cutters, kept cool with cutting com- pound, will work efficiently at very high speeds. A paste mixture of one part of powdered blue and four parts of vaseline makes a good substitute for Prussian blue. © SHOP MP iz Oh "HO. Pe. QsiexE 4 May, 19% Uti, W)} . Zi HEN a taper has been turned in the lathe by moving the tailstock, the work is not complete until the tailstock has been set back in the center. While most lathes have a mark of some kind to indicate when the tailstock is in the center, experienced mechanics do not de- pend on this marking for accuracy. There are at least three ways to be sure that the tailstock has been reset properly. One ‘is to turn a piece and, by “ miking” and resetting, obtain the correct setting. Another is to use a good arbor and a dial PAPER FEELER HEADSTOCK TAILSTOCK SPINDLE Fig. 3. Simple testing device to determine whether a lathe tailstock has been set correctly. Fig. 4. An accurate method of checking paral. lelism with a toolmaker’s square and angle iron, test indicator. A third is to use the devig shown in Fig. 3, which consists of a taper shank to fit in the spindle and a flat ex. tension with a 30-degree angle at the end, The use of the tester is simple. Th tailstock should be set to what is believed to be the correct position; then the cente is run in until it makes contact with the setting tool or with a paper feeler held as Fig. 5. A finishing tool that produces an excel- lent surface in the shaper, planer, or slotter. shown. The lathe spindle is revolved half a turn, and if the tailstock is correctly set, the paper feeler will fit just as tightly as before.—H. Moore. _ thought has been given to the problem of determining accurately whether a given piece is parallel or wheth er two pieces are of identical thicknesses. When the parts are very small, the mi crometer is not entirely dependable, for the adhesion of a lapped surface to the anvil and spindle end of the micrometet is enough to give varying results whea applied by different men. (See page 94.) In the method (Continued on page 116) Ma v

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¥, 19% May, 1929 g paral. tle iron, e device a ta flat a the end, e. The relieved e center vith the held as »L ERSE LOCK : n excel- slotter. ved half tly set, shtly as i to the ‘urately wheth- a 8 WORLD'S STANDARD OF ACCURACY e mi- ble, for to the -ometer s whet uge 94.) age 116) © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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way we MME. Finishing al the Spray Painting outfit No. 860. Mr. John F. Creamer, General Manager of Wheels, Inc., one of the largest auto wheel service companies in the U. S. says in relation to painting auto wheels, “Spray painting is the only way we can do it. Only manufacturers making large volume of wheels of the same size can afford to dip and centrifugal dry auto wheels. We have had every satis- faction with our Brunner Equipment and it makes money for us. We also use the Brunner Air Compressor for inflating tires.” Saves Money Brunner equipment saves money in every business where a large volume of painting is Model 300 Gun done—Brun- ner paint spraying equipment can save you money, in- crease pro- duction and give you a uniform finish. Model 721, Portable Outfit Send for Booklets Our Industrial Department is at your service. We will be glad to advise you and give you sound, practical information on Spray Painting. An interesting booklet on this subject is free to any business man who will attach the coupon below to his letterhead. Brunner Manufacturing Co. Utica, New York ATTACH-THIS-COUPON-TO-YOUR-LEFFERHEAD Brunner Mfg. Co. Industrial Dept. P. S. Utica, N. Y. Please send me your booklet on Spray Painting and Spray Painting Equipment. BRUNNER SPRAY PAINT EQUIPMENT —The only can do it— POPULAR SCIENCE MONTHLY May, 19% | a neighbor | uses his home | Drilling Holes in Claas Small Ones Are Bored with a Sharpened File, Large Ones with a Tube By E. E. ERICSON Fig. 1. How the point of a triangular file is ground for drilling glass. Take care not to draw the temper. - HERE can I go to get some holes drilled in a piece of glass?’’ I was asked recently by who workshop as a place to forget business worries. “I am not sure that I know,” was my reply, “but why don’t you bore them your- self?” My neighbor Fig. 2. The way a file is held in a brace and used to drill either window or plate glass. Note ring of putty to retain the turpentine. Fig. 3. When the tube method of drilling —or, more properly, grinding—is to be used, it is necessary to con- struct a wooden guide, as illustrated below. was one of the many who consider working with glass, and particularly drilling holes in it, a complete mystery. The explanation I gave him of the process of boring holes was essentially the following. For small holes in either window glass or plate glass, a triangular saw file makes an acceptable drill. Grind the point to make three surfaces corresponding to the sides of the file as shown in Fig. 1. It is better to use a grinding wheel that runs in water or oil in order to be sure not to heat the file, but if a dry wheel must be used, apply the file with very light pres- sure and dip the tip in water often. If the temper is drawn, the file is useless. To prepare the surface of the glass for Fig. 4. Shallow notches are filed in the end of the brass tube to help distribute the abrasive. drilling, mark the place for the hole by a scratching action of the point of the file. Then make a circular container around this mark, using putty or other plastic substance. Leave the glass exposed in the center and fill the little bowl with tur- pentine. The drilling is done with the file in a brace as shown in Fig. 2. A breast drill or a hand drill can be used for greater speed. Use light pressure and reverse the glass as soon as the point goes through. The process of drilling in this manner is not rapid but, unless a large number of holes are to be made, it will prove satis- factory. The size of the file selected will, of course, determine the maximum size hole that can be drilled in this way. For larger holes effective work can be done by using a brass tube. A suitable piece of tubing often can be had for the asking at a plumbing shop. Some such device as that shown in Figs. 3 and 5 is necessary for holding the tubing in place and perpendicular to the glass. It con- sists of a baseboard upon which the glass rests, a small block to serve as a spacer, and a two-by- (Continued on page 114) ;.

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PSSQar

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Why it is so easy to learn to type on CORONA # UR little boy has loved Corona ever since he was big enough to notice the letters.” “] learned to use Corona when I was sixty- eight. Itis much easier than writing by hand.” Scores of letters like the above have come tous. They show how easy it is to use Corona. If children too young to hold a pencil can use Corona, anybody can. If old people whose

CORONA IS THE WORLD’S CHAMPION PORTABLE ON 8 EXCLUSIVE POINTS 1. stRENGTH: Strongest frame of any portable typewriter — solid one-piece aluminum, rigidly braced. 2. stmpLiciry: Fewer parts than any other standard-kevboard typewriter. 3. COMPLETENESS: More big-machine fea- tures than any other portable typewriter. 4, EASY TO LEARN: Corona design is the result of 20 years’ study of the needs of beginners. 5. WAR SERVICE: 4n unequalled record for durability as the official portable of the Allied Armies. 6. popuLarity: 4s many Coronas have been sold as all other portables combined. 7. DURABILITY: Coronas purchased 20 years ago are still giving satisfactory service. 8. Beauty: Graceful in line; exquisitely fin- ished in every detail. CORONA The PORTABLE TYPEWRITER handwriting has grown shaky can use Corona, anybody can. To say that it is easy to operate Corona is understating the facts. It is astonishingly easy. Beginners, after reading a helpful little book that is given free with every Corona, can learn the fundamentals in just a few hours. In the very beginning, Corona was de- signed with the idea that it would be used by people who had no typewriter experience. That was twenty years ago. Corona is still built with the beginner in mind. All the needs of the amateur typist have been studied by Corona engineers. Every year we have im- proved Corona—made it more convenient. Here are a few advantages which make it the easiest typewriter in the world to operate: Adjustable Key Action—The touch can be made light or heavy to suit your requirements. Adjustable Paper Guide—Insures uniform margin on all pages of a manuscript. Back Spacer and Margin Release—These are conveniently located on the keyboard. Carriage Return Lever—This is made extra large and convenient. It enables you to per- form the two operations of spacing and re- turning the carriage to the starting point with one sweep of your hand. Extreme Visibility—Holds paper at correct reading angle.

POPULAR SCIENCE MONTHLY

Key Spacing—Same as on office type- writers. Standard Keyboard—Four rows of keys, exactly like a big office machine. Corona has many, many other features. There is not room on this page to describe them all. Other portable typewriters have some of these features. But no other portable has all of them. In making Corona easy for beginners to operate, we accomplished another result—an unforeseen result. The very features which enable beginners to write more easily, enable accomplished typists to greatly increase their speed. You owe it to yourself to drop into a store where typewriters are sold and see Corona, The minute you lay eyes on it you will realize why a million people use it—why Roosevelt took one to Africa—why 30,000 Coronas were used in the World War—why more novelists, more newspaper men, more business men, more schools and colleges use Corona than all other portables put together. For a small down payment you can take a beautiful new Corona home with you today. Don’t neglect this opportunity. Don’t let an- other day pass without doing something about it. Know now the joy of owning a sturdy, speedy, smooth-operating Corona — the World’s Champion Portable. An interesting illustrated booklet called “Corona Typewriters” which describes Coro- na in detail, and contains beautiful illustra- tions of the new color models, will be sent you upon request. No obligation. Simply mail the coupon below.

LC SMITH & CORONA TYPEWRITERS Inc 51 Madison Ave., New York, N. Y. Please send me the free booklet, “Corona Typewriters. ”

DIB in snn-cenqneceretsncsseniitpisstsscceipiasquingmeptecdaiiaddasten iia - Street.....-.- : 513 City. DONO iccascucuasinnnsiahen <a

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RETO A LS EAS ee ae

100 H. ere’s a Screw Driver you can use ds a CHISEL Op mariry you should not ask your screw driver to be a chisel, but it is a fine thing to have a screw driver that is so good that you can use it as a chisel in an emerg- ency. And that is what you get in a Bridgeport Red Crown. Its point is dual tem- pered by the pyrometer process—and twice test- ed before assembly. Look at the picture above. The craftsman has driven his Bridge- port Red Crown point clear thru a \-inch piece of steel. The point has come through as good as new! Yet this extraordi- nary Red Crown point is not all. The Bridge- port Red Crown has three other features— just as outstanding. Read about them be- low. Then ask your dealer to show you the Bridgeport Red Crown —identified by the bright red crown atop the handle. 4’, 5’’ and 6"’---50¢ each. If your dealer cannot supply you, order direct. Why Craftsmen Choose Bridgeport Guaranteed 1, You can’t twist the handle— the hexagonal h:ad and heavy steel rivet prevent turning. . 2. You can hammer the head—it's broad steel service takes the blows and protects the handles. . You can pry with it—its one- piece heat-treated blade with- stands tremendous leverage. 4, You can chisel with it—its dual tempered and twice- tested point won't mushroom, The bright red crown atop the handle identifies Bridgeport Red Crowns. THE BRIDGEPORT HARDWARE MEG. CORP. Bridgeport, Connecticut, U. S. A. America’s Largest Makers of Screw Drivers Bridgeport TRAOE TOOLS and HARDWARE SPECIALTIES POPULAR SCIENCE MONTHLY May, 19%

How I Built a Portable Workbench for Use in a Small Apartment By Puitre H. MILiter overcame the obstacle of having no place to work in a small modern apartment. In the foyer adjoining the kitchen was a clothes closet. It wasn’t very large, but why couldn’t I build a small cabinet and store it in one end of the closet—a com- bination bench and tool chest? As it was not my intention to make the cabinet a show piece, I used for lumber old cases and crates that I found in the cellar of a stationery and toy store on the corner. The only materials pur- <q chased were four hinges 244 in. wide, four handles for drawers, four casters, five cents’ worth of 2%-in. round-headed screws, and ¥ lb. sixpenny nails, cost- ing altogether sixty-nine cents. The tools used were a hammer, crosscut and rip saws, try-square, plane, ruler, screw driver, and drill. First I cut the two sides 34 by 114% by 30 in. and nailed a piece 3% by 134 by 19 in. across the front end of these at the top, and a piece 3 by 3% by 19 in. across the bottom and extending 3% in. lower than the ends of the sides—to allow for the thickness of the bottom. Two vertical pieces 34 by 134 by 25 in. were then nailed to the sides to complete the frame of the front. The bottom, 34 by 11% by 19 in., was nailed under the sides, the ends of it being flush with the sides. The back, 4% by 19 by 3034 in., was then nailed on. Before I | ERE is how a “home workshopper”’

Mr. Miller’s bench aided him in making this dresser and many other pieces of furniture.

SS

The apartment-size cabinet work- bench ready for use (above) and raised on casters (at left) so that it can be rolled away and stored in a closet. attached slides for the drawers, I com- puted the depth of the drawers by what! intended to keep in each and built them accordingly. The top I made of %%-in. stock. One piece 15 by 2014 in. was cut to run from front to back, extending 21% in. over the front and 3% in. over each side. The other section or layer of the top I made 15 by 19 in., thereby allowing %4 in. on each end

for a piece of quarter-round molding f5 in. long. I nailed the first board to the sides, front, and back, and then inverted the skeleton of the cabinet on the other board, the grain of which runs at right angles to the grain of the first one; and, after allow- ing 34 in. on each side for the molding, I screwed the first board to the second. When the cabinet was right end up, I had a smooth top without visible screws or nails. I then nailed on the molding at the ends of the top with 1-in. brads. Now for the most interesting. part—the method of mounting the casters on pieces of wood 31% by 12% in. that are fastened to the bottom of the bench with hinges set 34 in. from the ends. The width of these pieces is of great importance; it has to be exactly 31% in. so that when the cabinet is tilted each will flip outward of its own momentum and not hit the floor. If they were too wide, the weight of the cabinet would fall on the hinges and, of course, break them very soon. At this width, the weight rests on the corner of the cabinet, allowing a needed 4 in. before the hinges on the tilted side are opened to capacity. The casters are ball bearing and have flat tops or screw plates 1144 by 1% in. with four screw holes. They are set 1 in. from each side (Continued on page 118)

ie

© This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

FF aan

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May, 1929 POPULAR SCIENCE MONTHL Y STOP that CHATTERIN G This age-old cause of plane trouble was tackled sci- entifically by Millers Falls engineers. Smoother cut- ting depends on the pressure with which the blade is held at the correct cutting angle. So a 3-point bear- ing of the lever cap was added. This bearing keeps the cutter flat the entire length of the seat. It makes possible a hair breadth adjustment that holds and completely overcomes chatter. Another New Feature ... improved cutting edge The improved Millers Falls cutting edge is the re- sult of years of experience with fine tool steels. A es point bear- ing of lever cap No slipping, no chattering with the new Millers Falls Planes. Instead a smooth firm stroke that means finer work with less effort, that adds to the satisfaction and pleasure of a job well done, that removes completely the constant irritation of a chattering plane. new process of tempering the cutters electrically, gives the edge greater uniformity and longer life. Think what this means—more time spent in productive work, less time spent in sharpening and recondition- ing. And how much easier the work will be with these new planes. The new line of Millers Falls Planes covers every plane need. Sizes in bench planes from 7 inches to 24 inches, smooth and corrugated bottoms. 21 mod- els of block planes. But don’t take our word alone. Test out one of these improved planes. Then note the difference. Sold by leading hardware dealers everywhere. For more complete information on the Millers Falls Planes and the balance of the 12 major tool lines, send today for the new Millers . Falls catalog. There is no charge. MILLERS FALLS TOOLS MILLERS FALLS COMPANY NEW YORK: 28 Warren St. MILLERS FALLS, MASS. @ This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. CHICAGO: 9 So. Clinton St

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KCL a EE by Re, Ssh TIE as er nc ee AE SS ED 102 CHAMPION National Change Week... & a 3 4 Save the Price of New Spark Plugs NCE again Champion re- minds you that to enjoy per- fect engine performance during the next twelvemonths youshould install a complete new set of spark plugs now. You should renew even Champion Spark Plugs which give much better service for a much longer period than any other spark plug. If you have used your spark plugs more than 10,000 miles, a new set of the new improved Champions will restore new car power and speed and save their cost many times over in less gas and oil used. Moreover, the far-reaching im- provements, the time-tested and exclusive superiorities of the new improved Champions are so great as to warrant immediate equip- ment with them—no matter what spark plugs you may now be using. Make Champion National Change Week your yearly reminder to in- stall a complete new set of Cham- pions. It is a proved method of maintaining maximum engine efficiency and economy. Any one of more than 100,000 dealers will be glad to serve you. CHAMPION SPARK PLUGS TOLEDO, OHIO WINDSOR, ONTARIO POPULAR SCIENCE MONTHLY May, 1999 These Handkerchiefs Can Fly They Pass Magically Through the Air from One Test Tube to Another—An Easy Trick for Amateurs By GEoRGE S. GREENE Silk handkerchief and flag ready to change places. The thread, which is in one piece, isinvisibleata short distance, N PERFORMING the trick of the flying handkerchiefs, the amateur entertainer places two small silk handkerchiefs of different colors—or a handkerchief and a flag—in glass test tubes. While he is holding one tube in each hand, the handkerchiefs suddenly change places, each flying through the air. Suitable test tubes usually can be pur- chased at a drug store. Each is prepared by placing the closed end in a gas flame until the glass reaches the fusing point. A glass rod is applied to the tube and A small hole is formed in the test tube with the aid of a Bunsen burner and a glass rod. Pins Prevent Bench PREVENT a bench drawer from being pulled out too far and falling with its contents to the floor, dowel-pin AFTER DRAWER IS PLACED IN BENCH PINS READY TO BE DRIVEN IN How short dowel pins are inserted in the sides of a bench drawer to serve as stops The extra Now they have changed places. thread hangs below and can be discarded. drawn away in such a manner that when it is broken off a hole will be left in the bottom of the tube. The rough edge is softened by reheating. A loop is made in each end of a black thread and passed up through the hole in the bottom of a tube. The thread is drawn out of the top and each loop is carried over to the opposite tube, where it encircles the handkerchief—or flag— } that is stuffed into the tube. When the handkerchiefs are to change places, all that is necessary is to draw the tubes apart gently but quickly. This will cause the threads to pull the silks from each tube. In a flash the handkerchiefs fly through the air and enter the opposite tubes. Then they are withdrawn from the tubes and pulled free from the thread. Drawer from Falling stops can be inserted in the drawer sides as shown. The dowels must be a tight fit in the holes so that they will stay in place. If it is necessary to remove the drawer entirely at any time, the dowels can be retracted without difficulty by using pliers or pincers.—G. A. LurErs. A sUBSTITUTE for a garden hose washer can be made by removing the cork insert from the discarded cap of a soft drink bottle. With a sharp knife or a punch, cut a hole in the center equal to the inside diameter of the hose.—W. J. Rake. May,

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fa hen the 2 is ack » in is ) is ere ge che vill om efs ite he May, 1929 POPULAR SCIENCE MONTHLY 103 YOU HAMMERING 6y ELECTRICIT NO. 4 PORTABLE ELECTRIC HAMMER Capacity in concrete or brick up to 14” Weight - 15% Ibs. Price - $185.00 NO. 2 PORTABLE ELECTRIC HAMMER Capacity in concrete or brick up to 54” Weight - 10 lbs. Price - $145.00 NO. 6 PORTABLE ELECTRIC HAMMER Capacity in concrete or brick up to 114” Weight - 23 lbs. Price - $245.00 HIS is the method used in the majority of industries today, regardless of their size. There is no industry so small that “hand hammering’’ methods will suffice when electric tools are available which will hammer at the rate of from 2,300 to 3,300 blows per minute. Black €? Decker Portable Electric Hammers are manufactured in three sizes with a range from 14 to 114 inches in concrete or brick. They can be plugged into any electric socket, making them instantly available. A complete line of star drills, diamond point drills, chisels, seam tools etc., are manufactured for these Hammers, doubling their usefulness. If you have holes to drill in concrete or brick it will pay you to investigate these powerful, labor saving tools. Write for our new 8 page Hammer Booklet - also for details regarding our Time Payment Plan. Ue © Oe ee SOG © SS SOO eeeea @ 2 Wee @ w= Zee @ See e2e@eQe @ 222 OO SO OS S22 228228288 227° 22°22 The BLACK &? DECKER MFG. CO. Towson, Maryland Gentlemen: I am interested in your Portable Electric Hammers and will be glad to have further infor- mation regarding them. NAME ADDRESS © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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iSBn 7S Se nine EET 104, “TED THE TESTER” Pn poe p Weester Brush and oe ° Bristle came loose! An actual test. if itS worth Painting... Its wortha WOOSTER BRUSH RY a Wooster Foss-Set brush with Foss-Set bristles that can’t come loose—that won't shed on the surface when you're lacquering, en- ameling or painting. Wooster Foss-Set brushes are guaranteed. The Foss- Set process grips the bristles in a setting that can’t be dissolved By any painting materials. Be sure to get a Wooster Brush next time you paint—look for this little design on the handle or metal ferrule. Wooster Foss-Set brushes are made only by THE WOOSTER BRUSH COMPANY WOOSTER, OHIO Sold by Dealers Everywhere WOOSTER BRUSHES FOR PAINTING—VARNISHING—ENAMELING LACQUERING—KALSOMINING surtace and “Sas p-- gil — Lar Kot WHAT A GOOD BRUSH DOES The fine Chinese hog bristles of a good Brush work paint thoroughly imto every fissure and crevice — fill chem with paint and brush out | 1) j i} 4, \\ QE Mia. air bubbles and surface moisture, thus securing deeper penetration of the painting material. This means a better finish, greater surtace protection and economy when you paint with a Wooster Brush, because the paint becomes an seeegras part of the surface itself—not just a paint film” to crack or peel off. POPULAR SCIENCE MONTHLY May, 1929 = cna and enamels that dry in four hours are the latest development in painting materials. With them you can refinish a floor or other woodwork in the evening and use it the next morning or you can apply one coat in the morning and a second in the afternoon. These amazing new finishes can be obtained at all up-to-date paint stores in the larger cities, and it will not be long before they will be available everywhere. As they undoubtedly mark -another great step forward in finishing materials, especially from the standpoint of the home owner and amateur painter, a word about their manufacture will not be amiss. They are not merely old-line var- nishes and enamels with the drying forced by driers to the impairment of their dur- ability, but an entirely different product, made possible through the use of a new form of synthetic resin. This is produced from formaldehyde and phenol and is closely allied to bakelite. It is used in making the four-hour varnishes in place of fossilized varnish gums. After being incorporated with linseed oil, china wood oil, and other materials in accordance with the formula of the particular var- nish being made, it is cooked over varnish fires of the standard type. The enamels, of course, are a combination of four-hour drying varnish with the necessary pig- ments and coloring. Let us compare these new quick-drying materials with ordinary varnishes and enamels. Which is preferable is entirely a matter of whether or not quickness of drying is of importance. If there is ample time for drying, there is no reason for using the new type materials. In most homes, however, quick drying is a great convenience, if not of extreme impor- tance. This is true where there are chil- dren in the household, especially in the Renewing Floors Overnight Hours Make Feat Possible Enamels for Speedy Work Varnishes That Dry in Four By Bruce BRIGHTON Floors and other woodwork dry overnight when finished with the remarkable new four-hour types of clear varnish, varnish stain, or colored enamel, varnishing of floors, from which it is next to impossible to keep the little folks until the varnish has dried. Even with varnishes that normally dry overnight, the weather and the tem- perature of the room have so much to do with their drying that often they are still tacky or sticky the next day; and some- times under unusually unfavorable con- ditions, it is at least forty-eight hours before the finish has become thoroughly hardened. With the four-hour drying materials there is never the least ques- tion about the finish drying overnight. As to appearance, there is no difference between the finish produced by the new and old materials. The four-hour mate- rials also are quite as easily applied as other varnishes and enamels. OW let us compare the four-hour finishes with the cellulose brushing lacquers which came in with almost startling suddenness a little more than two years ago and have since enjoyed great popularity. It is not likely that our-hour varnishes and enamels will be used to any great extent in the field in which brushing lacquers have been almost exclusively used up to this time; their field is one in ,which the brushing lac- quers have never been extensively used. Lacquer has been used largely for finish- ing unpainted novelty furniture, such as magazine racks, tilt top tables, and the like, and for refinishing chairs and other small pieces of furniture about the house. For such work it is seemingly best adapted. ‘There is a very definite ad- vantage in being able to go right over the surface with a second coat almost imme- | diately after finishing the first coat and also in applying the trimming colors and finishing the piece at one time. There is @ fascination (Continued on page 113) © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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, 1929 it ur rk dry rhen new lish, , or mel, May, 1929 POPULAR SCIENCE MONTHLY 105 10,000: New Lon os Who will fly them? Keep them in repair? Young man, that’s your job There were only 6,077 pilots and 4,873 airplane mechanics licensed or pending the first of this year. Who then will fly the airplanes that were produced in 1928 as well as the 10,000 new planes which authorities conservatively esti- mate will be produced in 1929? Who will service these planes? This shortage of trained men, it is widely said, is the only fac- tor that can interfere with avia- tion’s development. Aviation needs trained men. Aviation needs you, young man. Aviation Offers These Opportunities When you have graduated from any of the Universal Aviation Schools, you know your sub- ject from a practical as well as a theoretical point of view. Uni- versal training is thorough. A pilot’s course prepares you for the government examination in whichever grade you have. qualified. The mechanic’s course qualifies you for examination as airplane Universal Aviation Schools A Division of the Universal Aviation Corporation apprentice mechanic and immediately puts you on a money makin; basis. The Aviation Business Course gives you a thorou ‘oun work in aviation which you may use in advancing yourself in any of the many diversified fields whidh aviation touches upon. At this date you may practically pick the field in which you wish to specialize, get your training through any one of the Universal Avia- tion Schools and be assured there is a place for you in the industry. Facts About Universal Aviation Schools To supply the present as well as the future need for thoroughly trained men, the Universal Aviation Corporation, a $10,000,000.00 concern operating over 5,000 miles of —— a day, has established a number of aviation schools at various airports out of which cae | operate. These schools have been given the finest, most modern aeronautical equipment available and have been placed in charge of the most competent instructors in the country. All instruction meets with ae requirements of the Aeronautical Branch of the U.S. Department of Commerce. Ifyou areambitious, anxious to really get somewhere in aviation and are willing to buckle down to what is perhaps the stiffest aeronautical course in the country, _ enroll in a Universal Aviation School. 25c Brings This Book “ Aviation —What It Means To You” an swersall your questions. It gives you infor- mation you should have before you ever decide to study aviation. In a frank, clear manner, without exaggeration, it gives you a true picture of the aviation industry to- day. Send 25c for your copy. Mail with the coupon, today. z v ‘ Corporation operates Air ._ en ae Lines between Minneap- 6 olis-St. Paul, Chicago, Kansas City, Omaha, Cleveland, Cincinnati The Universal Aviation UNIVERSAL AVIATION SCHOOLS pee : “THE SKYWAYS and Louisville,carrying OUR HIGHWAYS” UNIVERSAL AVIATION SCHOOLS Suite 1046-1055 Boatmen’s Bank Bldg. © , St. Louis, Mo. * New Air Lines are being 4 . » extended into other large cities as rapidly as condi- hs 2 LAS | AirMailand P rs. Universal Aviation Schools are Members of the U. S. Aero- Enclosed find 25c. Please send me the book “Aviation —What It Means to You.” Also complete informa- tion on [] flying []mechanics ([(] business course. nautical Chamber of Commerce

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POPULAR SCIENCE MONTHLY

May, 199

Blueprints for Your Home Workshop Ov blueprints can be obtained for 95 cents a sheet. In some cases there are two or three sheets to one subject The blueprints are complete in them. selves, but if you wish the correspond} back issue of the magazine in which the project was described in detail, it can be had for 25 cents additional so long ag copies are available. Other subjects be. sides those below are to be had; senda e stamped envelope for the complete list. VEE

Popular Science Monthly, mous 250 Fourth Avenue, New York In the Send me the blueprint, or blueprints, I ha which underlined below, for which I inclose....... & How 1 Ram anecdeancoer ee Described The No. Title inIssuesof Price a grea’ 2. Smoking Cabinet *Mar., °22 5c 15. Workshop Bench *Jon., °23 9% emineé. | 27. Kitchen-Cabinet Table Oct., °23 5c me | 30. Tool Cabinet, etc. *Jan., "24 Se co , 31. Sewing Cabinets Feb., °24 25¢ asthe 37. Simplified Bookcase Dec, “Ss 25¢ 43. Four-Tube Receiver + (battery operated) *July, 25 25¢ Lil 44-45. Pirate Ship Model *Feb., 26 50c 46-47. Galleon Ship Model May, °26 50c 48. Sailing Yacht Model *July, °26 25¢ 50. Airplane Model (Rise-off- Ma ground tractor, 36-in.) ‘“Sept., '26 25¢ a 51-52-53. Clipper Model, carefu Sovereign of the Seas “Oct., °26 75¢ *Oc

| 54. Five-Tube Radio Set t., '26 8 and gi | 55. Five-Tube Set—Details ‘Oct., ‘26 2%5¢ ¢ | 56. Bird and Animal Toys Dec., °26 25¢ you | 57-58-59. Constitution Ship to yor Model (‘‘Old Ironsides’’) *Jan., “7 75 60. Welsh Dresser ar., °27 25c On | 61-62. Viking Ship Model Apr., °’27 50c : | 63-64. Toy Motor Boat, 29 in. credit long hull May, '27 50c n OTs eC .65. Six Simple Block Puzzles June, ‘27 25 answt 66. Ship-Model Weather Vane Aug., 27 25c ee he 67. Toy Model of Lindbergh’s 5 New York-to-Paris Plane Aug., °27 25¢ a mal e Own 68. ——- — and ae -Troug able Te 25c 69. Flying Model (3-ft.) of : Th Lindbergh’s Monoplane *Oct., °27 25¢ natio . 70. Console Radio Cabinet Nov., °27 25¢ Th | 71. Console Cabinet—Details Nov., '27 5c e¢ | 72. Doll’s House “Dec., °27 25e wonc 73. Doll’s House Furniture ‘*Dec., °27 25c 74-75-76. Santa Maria Ship | ; can b “Carborundum stones have been a part of my A ny lia answ tool equipment both for work and experimentation Decorative Wall Shelves Jan., °28 25 Al . . Simple T Ch » for nearly twenty years. For fast cutting, keenness \Sieeicheeia rao a = “Pop ° one 80. High Power Unit for Elec- of edge produced and lasting qualities of the stone, thie Radio Set Me, 3 | man} I can always depend upon Carborundum. | ee aa ee been “A Combination Carborundum stone in the tool Sunil 82. Simple Single-Stick Air- book : - : end for plane Model (30-in.) Mar., ’28 _—25c box or in the home workshop is a great time-saver Bin RanBias 83-84-85. Mayflower Model Apr., '28 75¢ ° ° ’ Is in & ] diti Such this bookle 86. Racing Airplane Model im keeping one’s tools in first-class condition. Suc TOD AY (35-in. twin-pusher type) May, "28 a a stone will also furnish an incentive to keepthe ,.., 4. = reode a ederniscies —° ~*~ & Modernistic Bookcase Aug., °28 25¢ 89-90. Bremen Scale Flying , Model (3-ft.) Aug., °28 $0c 91. Modern Folding Scteens Sept., ’28 25¢ 92. Simple Baltimore Clipper Ship Model (8 in. on a Sept., ’28 25¢ 93. Three Modern Lamps Gct., °23S 25c 94-95-96. ee Steam- it : boat Model Nov., °’28 75¢ 3) | 97. Modern Electric Radio Set ( in One-Tube Form Nov., °’28 25¢ 98. Modern Electric Radio Set in Two-Tube Form Dec., °’28 25¢ 99. Modern Electric Radio REG. U. S. PAT. OFF. Set in Four-Tube Form Jan., ’29 25¢ ” - » har > edges on Chisels, Gouges, one Is . P Hatchets, Draw-knives, (signed) E. E. Ericson Wood Carving Tools, Scraper Knives, etc.

100. Modernistic Book Ends, Inte t ABRASIVE PRODUCTS Bovis ter gent" Dee. oe el | ta 101. Toy Fire Engine, Sprin- kant | kler, Truck, Tractor Dec., °28 25¢ of 28 THE CARBORUNDUM company, NIAGARA FALLS, N. Y. 102. Morrie Seaplane Model Mar., "29 6¢ an CANADIAN CARBORUNDUM CO., LTD., NIAGARA FALLS, ONT. Set (Old No. 41 revised to Mar., ’29) 25¢ y sone 104. Tractor Airplane Model May. 29 25¢ _— (cart dum is the Regi d Trade Mark of The Carborundum Company for its Silicon Carbide and is its exclusive property) *Magaszine only out of print. as thew The Carborundum C Niagara Falls, N. Y Name live it e ar rundum ompany, lagara alis, e . * 8» “I SFE CPS C6260 069. 00 6006000626 OS 699000084082 00 00 CSR EEE MAIL THIS Please send booklet P-1, “ How to Sharpen Wood-Working Tools.” (Please print name and address very clearly) \ Name CR oii acs Sada te ccsnitadakens<iuntesennscekeeee COUPON “ SN City a cnt onnnsdcds0ceecs: 660nenssecc<nene oo]

© This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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ee 78 2 ss.

Mar, 1929 POPULAR SCIENCE MONTHLY Are You All that you probably ever will want to know about science is told inthis one284-page book that will fit in your pocket or grace a library table. Curiosity-satisfying facts about the world weliveinare made instantly available to you in simple question-and-answer form in THE Pocket Guipe To SCIENCE. You are assured of the accuracy of the answers in Tue Pocket VERYBODY is talking about the fa- mous Popular Science Questionnaire.” In the panel is the list of questions of which the Questionnaire is composed. How many of them can you answer? These questions were prepared, after a great deal of thought, by a group of eminent scientists. Their test has be- come famous throughout the country asthe “Popular Science Questionnaire.” Like an Old-fashioned Examination May we ask you to make this test The carefully, reading the questions slowly POPULAR SCIENCE and giving thought to each one? When QUESTIONNAIRE you cannot answer one satisfactorily to yourself, put a zero (0) beside it. On the other hand, give yourself credit of four (4) for each satisfactory

Test Yourself Now . Why does radium continue to give out heat for thousands of —

answer. Then when you are through, years? see how near you have come to making 2. Ase the stars solid like the a mark of 100. 3. How was the earth formed?........-.-.-.--

ote = < o S. p & ° 4 i =] a o i 4 o =] ° ~~ . How do we know that the earth is slowly shrinking? -................... . What is an electric current?..............-- This is like an old-fashioned exami- nation, but you will find it fascinating. The questions all have to do with the wonders of the world we live in. All can be given quick and straightforward answers by any person of education. n wn : oc D) z < Q an Mo] oe fod Lal 2, oe E 3 o A. _ ~@ . - Do electrons really move through wire when an electric

All of the questions in the famous Bh ny ot el “Popular Science Questionnaire” and 10. How do muscles exert power?........... many hundreds of others, have now 11. What are X-rays? been answered, for the first time, in one See book—Tue Pocxer GuIpE To SCIENCE. 13. Why does heat expand things and cold contract them?.............-.---.--- 14. Why does the moon appear to change its shape from time to time? 15. What is the brain made of?............-... 16. Why is it possible that the in- side of the earth is growing hotter instead of colder?...................... 17. Why is frost more likely on a clear night than on a cloudy CODE eiarcciscncsencecccnssccencncossnssonac csecssaecencones 18. Does thinking use up the thinker’s energy? .-................-.----- 19. Which travels faster, electri- city or light? 20. What simple test will distin-

21. What makes the noise of thun- Into this \ 0 ELL EN OEE OT one bril- 22. Why would men ultimately liant book \ pe Me if all the green plants of 284 \ | | a & poses 23. Does the boiling of water re- densed ‘ae move the impurities in it?.................... outstanding #} el 24. How do the living cells of the facts about \ body get the energy with which the world we Be OP I IS octte ccctnscensccnsecenscnseces We im. \ 25. How is the speed of light mea- sured? Sisk

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Really Well Informed? Test Yourself with this Famous Questionnaire! Gulp To Science because it has been edited by Dr. E. E. Free, who has re- markable genius for condensing the known facts about scientific questions into easily remembered paragraphs. SPECIAL OFFER Tue Pocket GuIDETO SCIENCE is not for sale. It is offered to you without one penny extra cost, with a 14 months’ subscription to PopuLAR SCIENCE MONTHLY. Poputar SciENCE MonrtuLy “carries - on” from where Tue Pocxer GuipE To ScrENcE leaves off. THE Pocker Guipe gives you all that the scientists have discovered up to right now—PopuLar ScieNcE MontHuty will give you all the important, interesting and new discov- eries of science for the next 14 months. It takes over 300 articles and pictures every month to tell the readers of PopuLar ScriENCE Montu y all that has happened in the scientific, radio, me- chanical and automotive fields. Your Name in Gold Tue Pocxer Guiwe To Science is bound in beautiful flexible fabrikoid. Wewill stamp your name in 22-carat gold on the cover of Tue Pocket GuiDE at no extra cost to you if you use the coupon below immediately. We extend to you the Special Offer of a 14 months’ subscription to Poputar Science Montaiy (regular price by the month would be $3.50) with THe Pocxer Gur To Scrence —all for $2.95, plus the few cents’ postage. If you are already a subscriber to PopuLar ScieNcE we will extend your subscription 14 months if you accept this offer. Send No Money Send no money, just the coupon. If within 10 days after you receive the book and magazine you decide that you are not satisfied in every particular, you may return them,and your en- tire payment will be refunded grenoty and without question. Could any offer be fairer?

POPULAR SCIENCE MONTHLY 3-29 250 Fourth Avenue, New York I accept your offer of THE Pocket Guipe To SCIENCE and a 14 months” cubscription to POPULAR SCIENCE MONTHLY. I will pay the postman $2.95, plus the few cents’ postage when he delivers the PocKET GUIDE and the first issue of POPULAR Monrna ty. If the book and mag- rzine are not fully satisfactory to me I will return them within 10 days - = are to promptly refund my full payment. Please stamp my name n gold. ee ee ee ee

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Se ee een en Se ew Oa

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108 Stanley|Hammer Lifts 2 To / ) in a spectacular and con- vincing test a Stanley Nail Hammer has proved the fact that its steel head will not come off. By means of the apparatus shown in the illustration, the Hammer lifted a seven pas- senger sedan, weighing two tons, from the ground. A terrific strain. But this hammer is made to stand strain. Its thoroughly sea- soned handle of sound young hickory is driven forcibly into the head and fastened with two special wedges. The end of the handle is treated to exclude all moisture, preventing swelling and shrinking. POPULAR SCIENCE MONTHLY May, 1G Your hardware dealer can point out a number of other superior | features of Stanley Nail Hammers. | Buy one from him. Use it hard and often. You will find it an outstanding tool. TheStanleyRule & Level Plant, New Britain, Conn. STANLEY TOOLS The Choice of Most Carpenters Modernistic Smoking Stand By Herman Hsortu ODERNISTIC smoking stands have two advantages which should appeal to every man; they are substantial and convenient. The one illustrated, for example, is designed for hard service and, unlike the many ornate and fragile smokers which are manu- factured for anything but utility, it is big enough to hold a large stock of smoking materials and accessories. Indeed, it can be used as an occasional table. If the piece is to be given a stain and varnish finish, it should be of some good cabinet wood such as red gum; if it is to be painted with colored brushing lacquer or enamel, it can be of whitewood or séme other close-grained, easily worked wood. The tools needed are rip, cross-cut, back and turning saws, rule, try-square, marking gage, jack and block planes, 14- and %-in. chisels, brace, auger and gimlet bits, countersink, screw driver, 1-in. gouge, half-round file, hammer, hand screws, clamps, and miter box. First glue up the stock for the top, base, and shelves. It will also be neces- sary, if stock 14 in. thick is not available for the uprights, to glue together a 34-in. and a \%-in. piece face to face to form each of them. By reducing the diameter of the top and bottom 1 in., the uprights could be made from %-in. boards; while they would not look so substantial, they would be strong enough. The central shelves are made 16% in. in diameter and are flattened at the proper points to allow the uprights to be at- tached. They are decorated by fluting the edges with a gouge and smoothing the wood with a rat-tail file and sand- paper. The uprights are planed to the proper curvature—that is, a radius of 9% Construction of the stand. Note the position of screws and nails in the enlarged elevation. —_—_@ SS | ii | he eA ft My Sturdiness and simplicity are characteristics of this typically modern smoking stand. in. with the aid of a suitable template. | The method of joining the parts is clearly shown in the drawings. The screws passing through the lower top are| covered by the 4 in. thick upper piece, which is cut to the proper diameter, smoothed, and glued in place. This piece, as well as the 4-in. piece that is nailed to the bottom, should be cut from a sheet of plywood of the proper kind, if available. Obviously, the top and bottom also can be made of solid stock provided the top is fastened on in some way which does not allow any screws to show. To hide the screws with which the shelves are fastened to the uprights, first bore a hole equal to the diameter of the head of the screw and \ in. deep. In the center of this bore another hole for the screw itself with a gimlet bit or a twist drill. When the screws are in place and the heads sunk \ in. deep, cut the diamonds from a thin piece of wood, place one of them over a screw hole, and mark its outline with a sharp knife point. Then remove the wood on the inside of the lines with a 1%-in. chisel and glue the diamond in place. Materials for the Stand No. Pes. Parts : w. L. 4 Uprights..... 14% «(5 20 2 Topandbase. % 19 19 2 Topandbase. 4% 184% 18% 3 Shelves...... % 1634 16% Oe asia % 1% 134 4 doz. flathead screws 114 in.-No. 9 All dimensions are in inches ——_ @ This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. May, } will to | hol | cur | leas tral but

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eter, uiled | heet | ble. top | ‘not | the | | the | the the vist the and int. lue Chemistry everyday household articles are as important or interesting as tests on butter. It so happens, too, that butter is more commonly adulterated than other foods. Butter substitutes are occasionally found by chemists to be mislabeled with plain intent to defraud, especially in states which have poorly enforced pure food laws. The Federal Pure Food Law Free tests the amateur can make on shipped across the state line. If the ama- teur chemist wishes to check his work he can send part of the sample to his state food laboratory. The following so-called “foam test,” “curd test,” and “melted fat test’”’ have been used in food laboratories for years to aid in distinguishing between fresh but- ter, oleomargarine, and renovated butter. The latter is rancid stock that has been reprocessed by remelting the fat, deo- dorizing it, and then rechurning with fresh milk. The only apparatus needed for the foam test is an old tablespoon and a small flame such as is given by a candle. Light the candle and gently heat about one quarter of a spoonful of the butter sample in the spoon. Under these conditions good butter will boil quietly and without sputtering, although much foam will form on the surface. Oieomargarine will sputter like a boiling mixture of fat and water, but will give little foam. Reno- vated butter acts like oleomargarine. PERFORM the curd test, pour about a cup of sweet milk into the inner part of a double boiler, fill the outer part about a quarter full of water, and heat until the milk has reached nearly the boiling point. Add about two teaspoons of the butter sample to the hot milk and stove and substitute ice and ice water for the hot water in the bottom part. Con- tinue the stirring until the butter has again solidified. Under these conditions good butter will form granules which mix with the milk. Oleomargarine will col- lect in a single mass, which can be easily removed from the cold milk with the spoon. For the melted fat test, place about one half cup of the butter sample in a jelly glass and melt by holding the glass in water that has been heated to about 120 degrees Fahrenheit. This temperature will melt the butter but is not high enough to spoil the test. After a few minutes hold the tumbler against the light. The curd from fresh butter will have settled, | leaving the melted fat above it clear and | transparent. In the case of renovated | butter, the fat will be turbid from feathery particles of curd.—W.H. Hammonp. y Simple Formulas that 5, Will Save Time : and Money does not affect many locally distributed | foods since it applies only to products | | stir with a spoon until the butter is | melted. Then remove the boiler from the | PAYS + @+@ x @+ Os O+ @x-e@5-0 Holes bored in hard or soft wood without splitting. Drill- oint is revolved y pressing on handle; spring «brings handle back for next push, No. POPULAR SCIENCE MONTHLY Eight ““YANKEE” drill-points, 4 in. to # in., an in magazine in dle. Each drill- point tested. No. 41 Push Drill to have the right tool for the job. **Yankee”’ Automatic Push Drill is the right tool for boring in wood. Just push on handle. In a jiffy, it makes right- size hole for screw you want to drive. In the home, as in the shop, good tools earn big dividends on their slightly higher cost. Cheap tools are rank ex- travagance anywhere. Expert mechanics will tell you that **Yankee”’ tool-making can’t be copied -.. tell you to look for the name *“Yankee”’ when you buy a push drill, “Yankee” Push Drills No. 41.— Used by mechanics every- where, as the working mate of ‘*Yankee”’ Spiral Screw-driver. Price, $2.60. 44.— Adjustable Tension regu- lates pressure to suit kind of wood, size of drill, etc. Price, $3.15. *“YANKEE”’ on tool you buy means utmost quality, efficiency, durability. YANKEE’ TOOLS MAKE BETTER MECHANICS Name North Bros. Mfg. Co., Philadelphia, U.S. A. I want the best there is in tools: Send me “‘Yankee” Tool Book, showing Bit Braces with famous ‘‘Yankee’’ Ratchet, Quick-Return Sp two-speed (11-inch) Hand Drills, Ratchet Breast, Han Adivess ~.. 2. ee an a © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. iral Screw-drivers, new and Chain Drills, etc. Cem eee e meee ee ee EEEH HEHE EEE EEESE OSES OSES EES EEE EHEEOEEES

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SC OE ESE SO Soar POPULAR SCIENCE MONTHLY . a | i] i | i . What You See: High above the street, a workman sits unconcernedly on a scaffolding, doing a difficult job. What You Don’t See: The particular make of tool that workman is using —If he is using a file, the chances are far better than even that it is stamped with the Nicholson Brand. Nicholson Files are popular throughout all industries because they are sharp, dur- able and hang well in the file user’s hand. These same qualities make them preferred in the home workshop. Practically any hardware or mill supply dealer carries Nicholson Files in shapes and sizes for every demand. NICHOLSON FILE COMPANY Providence, R.1., U.S.A. A FILE FOR >» uae PURPOSE May, 19% ———___ Strong Joints Made with Clamp Nails By Davin WEBSTER be 4 nails may be used ag gy. stitutes for nails, screws, dowels, and glue upon work which involves joints like those illustrated. If your local hardware stores do not carry them, you can order them by mail from large hardware sup. ply houses. The ordinary clamp nail, which is shown at A, can be obtained in sizes ranging from %@ to %% in. in width and from }4 to 3 in. in length. A continuoys How clamp nails are used, particularly in mitered joints; method of cutting slots for them. form of clamp nail also can be obtained as shown at A!. Grooves or saw kerfs must be cut to receive the clamp nails as at B; these may be made on a well-conditioned cir- cular saw or by hand. To cut grooves by hand, prepare a guide block C and place it on the work D, as shown. The depth of the cut should be a little more than half the width of the clamp nail to be used. The members of the joint should be held firmly in correct relation to each other while the nails are being driven. Insert the wider end of the clamp nail so that the flange will cut its own path as it is driven and at the same time draw the joint into as nearly perfect contact as possible. One nail, as at E, will be ample for most joints, even without glue. © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. Ma‘ — C

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AY, 1939 ae de ls 3 sub. Is, and ts like dware order e sup. ich jg Sizes h and nuous ned L to uld . of ach en. s it the ple May, 1929 A —— Old Gun Converted into Floor Lamp N OBSOLETE shotgun or hunting A rifle or a discarded modern Army rifle can be made into a useful and orna- mental floor — - shown in the ac- nying illustrations. Oe the base 2 in. thick and at least 12 in. in diameter by turning it from wood on a lathe faceplate. Remove the putt plate of the gun and fasten the stock to the base with two large wood screws or lag screws % in. in diameter and 4 in. long. In case the base is not heavy enough for the gun, a recess with dovetail edges can be turned in the underside and Sportsman’s lamp made by adding a base, electric fixtures and shade to an old shotgun. then afterwards filled with melted lead. An electrician can supply the fixture and attach it by threading the muzzle. In the case of a muzzle loader. it will also be necessary to drill a hole through the breech or side of the barrel large enough to allow the fixture wires to be drawn through.— E. A. CLEVELAND. Table Extension Aids in Perspective Drafting ECHANICAL draftsmen are occa- sionally called upon to make per- spective drawings, and _ architectural draftsmen, of course, frequently have to prepare them. Unless the work is done on a table of unusual length, it is impossible SUPPORT ™_! A framework is laid on the drafting table to carry the pins for the vanishing points. to drive pins at the vanishing points and carry a long, straight edge out to them. Various expedients are used to over- come this difficulty. One of the simplest is illustrated. A light extension frame is made to rest upon the drafting table or desk. Pins to represent the vanishing points can be driven into the frame wher- ever necessary.—J. D. G. POPULAR SCIENCE MONTHLY this unique shaving cream. Mail the coupon GENTLEMEN: With a product such as ours the advertising problem is chiefly to get you to make this seven-day test. For results have proved that 86% of men adopt Palmolive Shaving Cream— once they try it. A seven days’ test on your own face beats all the laboratory tests that we can make. That is where sales are made. And that is how Palmolive Shaving Cream attained leadership in a compet- itive field in so short a time. Now, if you will return the coupon below, we will give you new ideas of shaving comfort. For we believe in proving our claims first—then asking you to buy. How it came about Shaving preparations had not kept pace with shaving needs. We studied long, then asked 1000 men’s advice \y To add the final touch to shaving luxury, we have created Palmolive After Shaving Talc —especially for men. Try the sample we are sending free with the tube of shaving cream. PALMOLIVE RADIO HOUR-Broadcast every Wednesday night— from 9:30 to 10:30 p. m., eastern time; 8:30 to 9:30 p.m. , central time; 7:30 to 8:30 p.m., mountain time; 6:30 to 7:30 p.m., Pacific Coast time — over station WEAF and 37 stations associated with The National Broadcasting Company, Well pay for Your Test Accept this 7-day trial tube at our expense. Prove these remarkable claims for These 5 Supremacies 1. Multiplies itself in lather 250 times. . Softens the beard in one minute. - Maintains its creamy fullness for 10 minutes on the face. 4. Strong bubbles hold the hairs erect for cutting. 5. Fine after-effects due to palm and olive oil content. Ww N They told us others’ shortcomings. And , we set out to fulfill them. 129 formulas, tried and discarded, finally brought suc- cess. Five unique features were attained. Now the test, please Suited or not, you owe it to yourself to try this remarkable shaving cream. You are the judge—it either pleases you or not—you take no risk. So won’t you mail the coupon now? and a can of Palmolive After Shaving Talc Simply insert your name and address and mail to Palmolive, Dept. B-3057, 595 Fifth Ave., New York City. oe oe oe oe ee ee ee es ee ee oe ee oe ee es oe es es ae!

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POPULAR SILVER STEEL ATKIN ip Paint Silver Steel Shi Finest Saw maPe fection Handle. SCIENCE MONTHLY AW

me. Non- Blades.

table fra Nickeled ster silver Steel

tter Saw for Workshop Use S ‘*Silver ogling * A Be Every ing ATKIN nese home workshop, a : x eek, clean, ogee _ 1B — — metal that aneee — ote i hops, in thousand Tia, Phere ATKINS Saws a e used. +5 your T f hese famous sa aking Te oe * Jeasure in ma i ble your { pete shop will dou me, labor an things, an¢ yo NeeSilver Steel’’—us¢ terial on every JO- keener

al jar Rip “silver Steel Cireu » Al tor | ey smooth, accurate cutting

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en yore better saw OF cutting ATKINS ety home workshop purpos¢- ms all sizes - +: Hack Saw ULAR SAW

CIRC Hand saws of Circular Saws Jed for smooth eS eee rece Sans arp uneavellthie ras: Blades and Frames « « p04 saws... — for wood or metal «+» °Ni" "" Miere Groover Of a Knives --: CIRCULAR . Saws ---° Mee iles , Grinding AW ee ae MITRE S see comment Scrapers « . inal Ideal Creo Sew tones as It saws. Wheels, ¢ ‘aware Dealer for the A A © _ $6 os be to start a home shop of aw ; your tool equipment. lets FREE Ss w Booklet int rfect File for every tng a sof erst helpful pooklets! —— a as Steel means faster. Write mf ull of practical suggestio’n’ of our poor sod “Mill Saws =. Saw Sense’ = and saw tools. oy oupon ircular saws el Goals with saws and their © below, TODAY

‘utting Saws, cular Metal-Cu — ATKINS 5 diameters and thickness ——— a E. C. ATKINS & COMPANY =. 1857 428 South Illinois St., Indianapolis, U. S. A. — << eet an AS AD AD AD SES Please send me ‘SAW SENSE," ‘* MILL SAWS" and ‘SAWS in the HOME,” or full | information on (state kind of saws you BM caccikenecssemiesthemae rt re | My Denker Ua .0i+corereeeeseorcncesecesecoooanccsscseneree ee seee see

May.

Making an Interchan 8 Screw Driver Set "7 OYS who are study- ing machine shop practice in high schools, vocational schools, and in shops can gain prac- tical experience in turn- ing, drilling, reaming, centering, knurling, mill- ing, filing, hardening and tempering by making the screw driver set illus- trated. Only one handle need be made, but blades of various sizes, as well as drift pins, punches, awls, scribers, nail sets, and center punches can be

- Lm " | 52 H.DR.RD. PIN “ & STEEL w/e TEE es — | PEEN IN,4 OF _ BALLABOVE /-— 23 til SURFIKE SPRING TO SUIT.USE EM) Ol6 SPRING WIRE Laie = ~ ~~ ' es li 3 ee % CHAMFER. DRAW THIS END DEEP BLUE

HARDEN AT 1450 DRAW AT 470

Be L

‘RADIUS ----~ lL PUNCH FOR PEENING BALL MAT. DR. RD. HARDEN Interchangeable screw driver blades with a handle, which may be used for other tools, made up and inserted into the hande The equipment required is as follows; Bench lathe, drills, reamers, knurling tool, file or mill, and hardening furnace, The operations for the handle ar: Cut 3 in. off a piece of 1%-in. drill rod Face and center one end. Drill and ream .313-in. diameter. Drill hole with No. # drill. Drill and file elongated slot. Tum Jg-in. diameter and chamfer. Knut. Harden and draw head to a deep blue. For the screw driver blade shown the operations are: Cut 214 in. off a piece of 5¢-in. drill rod. Face and chamfer end. Turn down blade. Drill holes. Mill or file the blade. Insert pin, spring, and ball. Harden blade and draw. For peening ball, a small peening punch can be mate like the one shown.—ALBERT NELSON. Cleaning Oily Shop Floors O KEEP the floor of a shop in goo condition, lime is sometimes used] instead of a sweeping compound. It is) swept over the floor every day in sucha) way that very little remains on the wood,’ but that little counteracts the effect of ail and grease and makes it easy to clean wp whatever has fallen on the floor. The treat’ ment, if persisted in, improves roughly used floors—Epwarp PIraNIAN.

This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

SE _ we ‘283 PREBE? ee ee oe ae ae

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USH FIT with a tools, handle. ollows: nurling urnace, le are; ill rod. d ream No. 4 Tum Knut. dlue. wn. the iece of r end. Mill or d ball. ening SON. Ors 1 good used | It is) such & wood, _ of oil an up May, 1929 Tt Boece Overnight (Continued from page 104) -) usi ials that dry before your eyes. Arr t a eeaidull aot al lacquer finishes is pleasing to the majority of people and cor- nds with the sprayed lacquer finishes of the highest-class furniture. With the improve- ments that have been effected in brushing lacquer during the past year, the home worker asa rule has no difficulty in using them for the ‘hing of small pieces. fowthes it ieee to comparing the four-hour varnishes and enamels with lacquer for such uirements as the finishing of floors and inte- rior woodwork, the advantages are in favor of the newer materials. The varnishing of a floor, for instance, is a different matter from doing a small end table or a sewing cabinet. It is not so easy to apply the cellulose-type lacquers on a surface of this kind and handle the brush so deftly that laps will not show. This also is true of interior woodwork. Very little brushing lacquer has been used for this pur- by home decorators, although professional painters have made effective use of lacquer finishes in some public building work of the better class. The durabie new four-hour varnishes and enamels, on the other hand, are just the thing for floors and woodwork. They can be used as easily on large surfaces by the amateur painter as the ordinary varnishes and enamels which he has been accustomed to use. -E SUMMARIZING, the best current prac- tice for amateurs seems to be as follows: Brushing Lacquers. Use for unpainted fur- niture and woodenware novelties, for refinishing furniture, and for all similar decorative re- quirements. Four-Hour Varnishes and Enamels. Use for floors, interior woodwork, and other architec- tural requirements. Standard Varnishes and Enamels. Use for all purposes where a varnish or an enamel finish is desired and there is ample time for the surfaces to dry before use. It should be remembered, of course, that there will always be those who have a decided preference for either an enameled or a lacquered finish, as well as certain individual requirements which may make one or the other way more suitable. The preceding classification is purely for the convenience of those who have had little or no experience with the various finishes; those whe have used them to a reasonable extent will understand the differences from actual experience and can use their own judg- ment. Four-hour varnishes and enamels may be applied over either new wood or previously painted, varnished, enameled, or lacquered surfaces. Prepare the work in the usual way in respect to cleaning, sandpapering, and dusting. Generally speaking, the handling of the new materials is the same as the old-line varnishes and enamels; however, a few precautions should be taken. Being generally of a heavier nature than the ordinary varnishes and enamels, they should be flowed out in a thinner coat than has been the usual practice. The surface can- not be brushed for as long a time and a closer watch must be kept for sags, runs, and other defects. Formerly some painters made it a practice to coat a considerable amount of sur- face before going back and “picking up” runs with a corner of the brush, but it will be found that this cannot be satisfactorily done with the four-hour drying materials. While durability was sacrificed to some ex- tent in the first finishes of this type placed on the market, improvements have been dis- covered, until now many of the high-grade makes of four-hour drying floor varnishes have practically the same durability under hard wear on floors as long-oil and spar varnishes of well-proved quality. POPULAR SCIENCE MONTHLY 113 Wouldn't you pay 2¢ to prevent §200 Mistakes? . «+ Then send for this FREE book ET this FREE book, “How To Judge a Used Car,” be your insurance against a mistake that may cost you hundreds of dollars! Two cents brings you trade information compiled from the years of used car buying experience of many acknowl- edged experts. It brings you 32 interesting pages of text, every paragraph of which holds some valuable hint on used car buying. There are pictures illustrating just what to look for in the used Pledge to the Public on Used Car Sales 1 Every used car is conspicuously marked with its lowest price in plain figures, and that price, just as the price of our new cars, is rigidly maintained. 2 All Studebaker automobiles which are sold as CERTIFIED CARS have been properly reconditioned, and carry a 30-day guarantee for replacement of defective parts and free sérvice on ad- justments. Every purchaser of a used car may drive it for five days, and then, if not satisfied for any reason, turn it back and apply the money paid as a credit on the purchase of any other car in stock—new or used. (It is assumed that the car has not been damaged in the meantime.) car you want. How can you tell the model ofaused car? What dospeed- ometersshow? What docode prices mean? How would you set a fair price ona used car offered by a friend? How do you avoid “orphans”? Why does the Studebaker Pledge give you five days’ driving trial? Ittakes only a2cstamp — to bring youthervightanswers © 1928 The Studebaker Corporation of America —mail the coupon now! 130,000 people have saved money by mailing this coupon! | THE STUDEBAKER CORPORATION OF AMERICA : | 4) Dept. 165, South Bend, Indiana l ; Please send me my copy of your valuable free booklet, “How to Judge a Used Car.” | | STUDEBAKER. Builder of Champions PR RNC

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114

POPULAR SCIENCE MONTHLY May, 1929

The Same .- Fast, Accurate Every kind of woodworking operation

COMPLETE OurriT for home use and profitable commer- cial work, including lathe = and many useful at- tachments

PLANER > <—-MOTOR Amazing low price This complete all-electric shop costs less than most other outfits and gives you an excellent value! The Workace is fast, accurate and easy to work with. Planing, sawing, turning, drill- ing, grinding, sanding or buffing—you save time on every operation, do better, cleaner work, too! It has ample power, strength and capacity to do any job quickly and economically .. . mitering, tapering, rabbeting, beveling, slot- ting, cross-cutting, ripping—anything! Every unit works from the G. E. motor. The regular Wallace UNQUALIFIED GUARANTEE as- sures replacement of defective parts for one year. This is a simple straightforward offer—no exaggeration, no red tape—just plain facts. If you want to make woodworking your real hobby—or a real source of income—send this coupon. © SEND TODAY J. D. Wallace & Company, | Wilcox & California Ave., Chicago, Illinois. worker, including your easy terms.

Attachment $10 Make everything out of wood with the famous er, saw, _= HAP ' ° es diederle motor — WomRaAee | Electric aN ctric SANDING BUFFING GRINDING ATTACH- MENTS

INCLUDES ALL THIS: 4” Planer 8” Circular Saw 6x36” Lathe 8” Disc Sander 6” Buffing Wheel 5” Emery Grinder \%" Drill Chuck 4 H.P. G.E. Motor, 110-Volt, A.C., 60 Cycle. Endless V-Belt, two 4” and one 24%” V-Belt Pulleys, Cast Iron Sub Base and 10 ft. Cable with separable Plug. The Planer and Circu- lar Saws are each com- plete units and may be purchased separately at the correspondingly low price of $25.00 each.

EASY TERMS Small Down Payment $9 Per Month Many pay for their Workace Shop out of the profits it makes .... small down payment brings the Workace complete and ready to set up for immediate use. The monthly payments are so small you'll scarcely miss the money .... Send the coupon now—today zo ET OUTFIT IGHT Y | I want to know ALL about that Workace Electric Wood- |

$e Drilling Holes in Glass (Continued from page 98) four through which has been bored a hole ; large enough to allow the tube to rotate freeh In the process of boring with a tube which should be cut square on the end, carbor or other abrasive powder is used as the of ing agent. In order to allow this powder to enter under the edge of the tube, eight or more shallow notches are made as shown in Fj The *ig is then fastened on the worktable ag shown - » Fig. 5, and the plate placed in Correct position under the tube. Carborundum powde may be poured into the tube or applied outside

Fig. 5. Grinding a hole in plate glass with a brass tube charged with fine abrasive powder. of it, together with a small amount of water. The glass is clamped down or wedged in to pre- vent its moving when the boring begins. A rose countersink or a reamer set in the brace or drill stock will serve to rotate the tube,

for no great power is necessary. The use of a drill press or lathe or any other application of motor power reduces the time necessary for the job. If care is taken, the tube can be allowed to cut through the glass, but a safer way is to re- verse it, provided the jig can be fixed in ex- A little practice will teach just how much pressure can be applied for best results in cut- ting. After the groove has been made, it should be kept filled with water; and additional abra- sive should be applied when necessary. If the edge around the hole is somewhat sharp or rough, polish it with carborundum powder held on a piece of wet cloth or rubbing felt. Striping with Lacquer AFTER painting a cabinet with a small air brush, I wanted to draw some very thin, fancy lines on the corners with dark lacquer. Knowing the difficulty of doing fine striping with a brush, I removed the lead from a dis- carded mechanical pencil and turned the mech- anism until the hole at the point of the pencil was plugged with the wire that pushes out the lead. Removing the cap and eraser from the other end, I filled the barrel with thin lacquer. Then I released the wire at the writing end a trifle and did the striping as if I were drawing with a pencil.—SamvuEL TRroNcoso.

BeroreE painting exterior concrete or stucco, scrape off any efflorescence or white spots apply a wash of 3 Ibs. sulphate of zinc to 1 gal. of water.

actly the right position on the opposite side. |

© This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

Page 111

fay, 1929 ASs hole just e freely, e, which rundum © grind. wder to or | Met table as | Correct Powder Outside th 7 der, vater, D pre- n the tube, a drill notor ed to ‘0 Te- n ex side. nuch cut- ould bra- the pD or held May, 1929 “Ten Thousandth”’ Touch (Continued from page 94) have affected the flatness of the antes onl perhaps the spindle face, as is hown at E, which will produce the same kind reser. When this is discovered, the anvil and the spindle must be lapped to flatness, or else the tool returned to the maker for the repair. ; Figure 7 shows a test that will reveal an inaccuracy of this type. The anvil is slightly blackened with a delicate coating of soot from a candle. When the face of the spindle is brought into contact with the anvil, the points that meet, or where “the shoe pinches,” are instantly shown. Another way to test the spindle and anvil for parallelism is to use a narrow strip of shim metal as a feeler as in Fig. 8. The feeler should be equally tight at all points. The simplest test for the truth of the spindle is by revolving the spindle against an indicator as in Fig. 9, while the micrometer is clamped to the bench. ITH these various tests made and re- ted from time to time, we can know that our micrometer will measure “‘right to the scratch,” always provided that we supply the one indispensable and important factor—a per measuring pressure. For those who have small experience or whose fingers lack sensitiveness, the use of the ratchet is best. The ratchet, however, has the disadvantage of lessening the control of the fingers on the barrel. On very exact measure- ments it may even defeat which it was designed; indeed, it is rarely used highly accurate work to do. however, there is but one way to acquire the sistent practice. Objects of the same length or diameter may give different readings, as shown at a and b in Fig. 10, because the jaw surfaces are worn at the outer ends, as at B, because the jaws are disaligned as at C, or because the bar has become worn or sprung, as at D and E. effects in each case will be different, but a study of the diagrams from A to F will suggest the best ways of testing. A caliper cannot be expected to be as accurate as a micrometer, but if a correction seems necessary, the best plan will be to send the tool to the maker. While many of the tests and checks that a good thought too far, it must be pointed out that if we want to work “right to the scratch,” none of them is superfluous. All of our tools must be checked and rechecked to an accuracy more precise than we ourselves expect to ob- tain in our work. In almost every case the remedy for error is for he has the facilities and the skill required before he can do that, it is up to you to find out when your tools are “out.” _ Experienced mechanics will recognize in this series of articles by Henry Simon —the present article being the sixth—a and practical value to the literature of the machine shop. As a mechanic, engineer, designer of teols and fixtures, manufacturer of precision tools, and now a writer of international reputa- tion on mechanical topics, Mr. Simon is placing at the disposal of the readers of this department the knowledge ac- quired in studying shop methods for many years. The next article, which he wrote as a sequel to this, is scheduled for early! publication; it will discuss the use of squares. by. toolmakers who habitually have much | In any case, | have been outlined may appear to be carrying | to return the tool to its maker for correction, | to do a first-class job in reconditioning it. But | contribution of outstanding originality | e purpose for | “ten thousandth” touch, and that is by per- | What has been said about the micrometer | applies in large part also to the vernier caliper. | The | POPULAR SCIENCE MONTHLY Norman Rocnwel [ tells fi Heng 115 Jim Henry—famous Mennen salesman—is interviewing some famous users of Mennen Shaving Cream. ... This photograph shows him talking to Norman Rockwell, the famous painter. ... Mr. Rockwell is seen working on a painting for the front cover of the Saturday Evening Post. oe i ean put more Chuckles in my pictures when Pve had this COOL shave” Now ROCKWELL:— ‘Sure, Jim, I’ll give you the dope on the artistic shave. . . I like to paint ho- boes, but I certainly don’t like to Jook like one. .. That’s why I shave care- fully—every day... Being a particular cuss, I’ve experimented with shaving creams almost as much as I’ve exper- imented with colors. “T guess I was one of the first to try that Menthol-iced of yours. .. I don’t know what’s in the cream, but I do know that it gives my face a keen cool tingle that I’ve never had from any other shaving cream. . . There’s a real kick to it! Some day, maybe, I'll do a painting of a happy shaver with his tube of Mennen. You know, Jim—that would be a self-portrait!” Mennen Menthol-iced — The Young Man’s Shave! Tuere is a dash and a cool invigora- tion in Mennen Menthol-iced that is typically young—modern! The lather MENNeh has a “get-up-and-go” feeling to it that fitsin with young ideas. Menthol, blended into the cream by a secret process, gives your shave a mountain- air COOLNEsS such as you never felt before! The minute the rich creamy lather bubbles up from the brush you'll say to yourself, “Here is some- thing different!” Dermutation Improves Shaves! MeEnneEN Menthol-icedShavingCream is the newest member of the Mennen line—a modern team-mate for the regular Mennen Shaving Cream. Both creams have Dermutation — a three- way shaving improvement — exclu- sively Mennen’s. . .. Dermutation 1. Softens the beard. 2. Lubricates the razor blade. 3. Invigorates the skin. The proofisinatrial. Send the coupon! After the shave—Mennen Skin Balm. It protects the skin and removes “‘face shine” ... non-greasy. Mennen Talcum for Men—the man’s powder that does not show... Great after a bath, too! MENTHOL-ICED SHAVING CREAM ' Jim Henry’s treat—14 COOL shaves 'M HENRY, The Mennen Company ,. Dept. P-2, ee pe Jim If Mennen Menthol-iced is as good as you and Norman Rockwell sayitis, send me 2 FREE tube. And a trial tube of Skin Balm, too.

Page 112

116 POPULAR SCIENCE MONTHLY The “mean job” is usually a matter of “mean” tools. When you can get a reai kick out of a pipe job; when you can get non-slipping pipe wrenches and non-backbreak- ing stocks and dies why not do it? You Can, Too Pipe tools aren’t all alike—some are good, some not so good. Greenfield has made it easy for everybody to get good ones, be- cause all Greenfield Pipe Stocks, Vises, Cutters, Pipe Wrenches, etc., are painted red. That red field. for you. NEW YORK FIELD ET 15 Warren Street GREEN GREENFIELD, Pipe work doesn’t need to be a “Mean Job” DETROIT: 228 Congress Street, W Canadian Plant: Greenfield Tap & Die Corp., of Canada, Ltd., Galt, Ontario “PAINLESS PIPE THREADING” color guaran- tees that the tool will work well, stand up well, and can be bought at the right price. Of course, experienced plumbers don’t need the color—they know quality when they see it, but the red paint is helping thousands to be sure that the pipe tools they buy are all they want them to be. Most hardware stores sell Green- field Pipe Tools, or can get them But in case you have trouble, write us direct, at Green- CHICAGO 13 S. Clinton Street BURN YOUR NAME ON TOOLS N CO. aa IrA East Stack St., Portiand, Oregon wirrs KOGR AF TOOL CHEST For Exacting ARK Your ae Toots FromThett. write with elec. chit ted" Toolmaters eet and fin 3 4-—, tian P ree Catalog any metal, wrijng on paper wii Send for it today. $3.80 prepaid interest: € H. GERSTNER & SONS day. om free. Write te- 565 Columbia St. ~ a= ED Dayton, Ohio. = )MPLETES YOUR MACK $475 With Chuck Fast THE NEW IMPROVED EVRY-USE ELECTRIC MOTOR ATTACHMENT ens directly on motor shaft, no pulleys i grindst uffs : Without Chuck 2,beits Made y. Holds ° brushes, drills, etc. as pulley. $225 Postage prepaid if © UNITED ELECTRIC MOTOR CO. 178 Centre St., Dept. D5, New York Serves , and 5/8 inch shafts. State size. i fi ies order. © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. Ee: May, 19% ann Hints for the Shopman (Continued from page 96) which will be described, use is made of this property of lapped surfaces to stick Only elementary tools are needed, yet the tes while comparative only, will reveal the - ence of an error of about 1/40,000 in. and prove the truth of parts within this limit. At A and B in Fig. 4 is shown the usual] tool. maker's angle iron and beam square, ]f ; assumed that each is lapped so that they a practically perfect and that the beam of the square will stick to the angle iron. If the beam of the square is wrung to on face of the angle iron and the blade moved down to the other face, the blade should make contact with the second face so perfectly tha no light will be visible. If light is visible the error is at least 1/40,000 in., since this is the ¥ . . ir | ity et ‘eit | - | | 45 | 457 + fe | \n ‘— Mend ‘* } or J \" LENGTH OF TAPER TO SUITLATHE =! Fig. 6. Set of live tail centers which are useful | fcr turning pipe or tubing in a small lathe | smallest opening through which light can he seen by the naked eye. If the blade is raised from the contact, there should be present the so-called “‘sweat mark,” which will also in- dicate that the blade was in uniform contact with the angle iron. Now, if a gage block or jig part such as Cis placed between the angle iron and the square blade, its parallelism will be indicated in the same manner. If two gage blocks are to he compared, as D and E, their equality will be shown if light cannot be seen above either one. While the inaccuracy of any given piece of work cannot be measured definitely by this method, it should be useful in bringing parts to exact parallelism, and in checking one part against another.—DanieEL F. Moriarty. FIGURE 5 shows the use of a tool that pro- duces an excellent finish on steel, wrought iron, or bronze in the planer, shaper, or slotter. Its principle is that of shearing off a thin, curled shaving with the side of the tool. As will be seen from the sketch, the cutting edge is at an angle of 30 degrees from the center line and is formed to a 4-in. radius, so that the cut- ting is done at a point near the center of the tool. The point should be about 1 in. thick. The clearance should be 2 degrees. The tool should be used with a fine feed; and when steel or iron is being cut, oil should be used as a lubricant. In machining most bronzes, no lubricant is required. The depth of cut should be about .020 in. The tool should be stoned to a keen cutting edge. Often when using this tool it is hard to see the tool marks at all—A.spert M. Tuomas. HEN pipe or tubing is turned in a small lathe, large centers of some type are neces sary for the tailstock. More satisfactory re sults will be obtained if these centers are made to revolve. In Fig. 6 is shown a set of live tail centers that the writer made for a 9-in. lathe. For larger lathes, the proportions can be im creased. The revolving parts are machine steel, casehardened, while the shank is of tool steel, left soft.—Frank N. CoaKLEy. ——

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May, 1929

POPULAR SCIENCE MONTHLY

ae —— Varnishing a Front Door (Continued from page 90) can be obtained when you can ee treat door with a temporary shed poets and remove it for refinishing to a room that can be kept free from dust. It goes with- out saying that the edges should be finished with the same care as the exposed surfaces; otherwise moisture will get into the wood and ious damage. Ties of oak - finished in the same way except that if a smooth, glossy, and well-filled surface is desired, paste wood filler must be applied after the stain. For a door that is to be a natural or light oak color, use natural ste filler; for brown oak, use a dark oak or walnut filler. The filler comes in one-pound

The Materials Needed t. ready-mixed oil or spirit stain or wood 4x. (oil for new work and spirit stain for old). 1 lb. paste wood filler, either natural color or the shade desired. 1 pt. spar varnish for exterior use. \% pt. bleached or white shellac and 4 pt. alcohol to thin it (used only for a two-tone gray stained finish with white filler).

and larger cans; it is a heavy paste, which must be thinned to a thick, creamy consistency with turpentine. it to stand for from five to fifteen minutes until the surface becomes flat, and wipe it off with a wad of excelsior, waste, or rags. Wipe only across the grain, but clean the surface well to avoid a clouded, dirty finish. If you wipe with the grain, you will drag the filler out of the wood cells and defeat the object of filling. The same is true if you start wiping before the filler is flat; yet if you allow the filler to set too long, it will be tough and hard to wipe. At the right moment it will roll up and off the surface easily, leaving the cells well filled. A second time over with clean excelsior or rags may be necessary to get it all off. Allow the filler to dry hard overnight and then sand the surface with No. 0 or 44 paper. | Clean the door with a cloth damp with turpen- tine or benzine, and you are ready to varnish. Some oak finishes, such as weathered and Jacobean brown, are not filled; the open wood cells remain visible as part of the finish.

HE two-tone gray finishes on oak are ob- tained by using a ready-mixed gray stain, followed by a thin coat of white or bleached shellac. For this purpose thin the liquid shellac you buy with an equal amount of alcohol. Spread it on thin and when dry (in about an hour) sandpaper it lightly with No. 0 paper. After that apply a white paste filler and wipe as described above. You can buy white paste filler in some large paint stores, but if you cannot get it, use natural paste filler to which a very little white lead (not more than one fifth of the bulk of the filler) may be added to make it whiter. Take out of the pail or keg the lead that is thick and has little oil; then thin it with a little turpentine before adding it to the filler. For finishing, use the lightest colored spar or outside finishing varnish you can get; very dark varnishes spoil the effect of a gray finish. The gray finish, as well as the weathered oak and Jacobean finishes, are best rubbed dull. A high gloss is not appropriate. Birch, gum, redwood, and cypress require no paste filler, and the finishing is as described for pine doors. Birch usually is stained but the other three are often finished in their natural color, without stain. _ A novelty finish sometimes used on cypress is called Japanese sugi. (Continued on page 118)

Apply the filler with an old, short-bristled paint brush. Rub it well into the wood, allow |

Motor ~ \ cms

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“He who robs me of my power steals that which enriches him not but prevents me from starting quickly and going somewhere with such ease and pleasure as never dreamed of in the world before.” _< Apologies to Shakespeare) Sip POWER in your motor is dependent on tiny electric sparks exploding thousands of charges of gas in the cylinders of your car every minute. Every time one of these sparks is weakened, delayed, or missed entirely, there is a loss in engine power. That’s why spark plug wires are so important! The Camoah gang of Motor Power Thieves constantly prey on the spark plug wires and cause electric leak- age which thus affects these explosions—result: lost motor power and more gas used. Eighi out of ten cars are suffering lost power from this cause. ‘ cr ar

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POPULAR SCIENCE MONTHLY TET e 6 6 FREES ES _—_——___. Power and pep go into the job when you get these wrenches into your hand. They make light work of your hardest tussles with nuts and bolts. Engineers’ Set No. 108*4(shown above) takes the following sizes of nuts, bolts and cap screws: | S.A.E. U.SS. |Hex. Hd) nye, | Ex- Number | Milled | Bolt | Cap Sc.} pote | creme Openings} Size | Size | size | Lgth. £41723 torr | -—- ”At —} 4t M1725B | t-te | +- | w+ | 4-4] 5 M1729 ++ —s vets et] M1731A ++ —} +++ + OF M1034A | H-ite | -—+# due 4-+! 10% These wrenches of Chrome-Molyb- - denum steel will fit practically every nuf and bolt on all standard makes of ears. Regular $9.75 setin canvas bag, price $8.75 with the Coupon below, The SPEN' CER NGS & Compa B eg TP Goun.US. Visitors always weleome New York: II Park Place Chicago: 565 W. Washington Blvd. THE BILLINGS & SPENCER CO. Hartford, Conn. SEND ME your Engineers’ Wrench Set No. 108% with 5 Chrome-Molybdenum Wrenches—regular $9.75 set in canvas bag— for $8.75 (check or Money Order attached). Town & State Pn ri i ae Varnishing a Front Door (Continued from page 117) The surface of the wood is burned with a gaso- line blowtorch until uniformly charred; it is then scrubbed with a steel wire brush to remove the black char and yet not cut through the beautiful brown color of the wood underneath. This removes the soft pulp wood and leaves the sap veins standing in high relief. After wire-brushing the surface, brush it off and fill it with a white paste filler as described for the gray oak finish. Wipe the filler and let it dry. Finish with a thin coat of the light- est colored spar varnish or exterior varnish you can get, thinned about twenty-five percent with turpentine. When dry, apply a coat or two of the same varnish as it comes from the can. The last coat should be rubbed dull for the best effect. Wax is the usual finish on sugi interior doors but will not last outside. Another article by Mr. Vanderwalker on refinishing outside doors with paint is scheduled for early publication. Both among professional painters and ama- teurs, Mr. Vanderwalker is recognized as one of the most thorough and practi- cal writers on painting and decorating. Casting Concrete Seats (Continued from page 86) For one seat, 1 bag cement, 1/4 cu. ft. sand, and 2 cu. ft. gravel will be ample. In placing the seat in its desired location, dig holes about 8 by 16 in. in area and about 10 in. deep for the ends to rest on. These holes are filled with a mixture of one part cement to three parts sand and gravel. Let this dry overnight and then lay a mortar of one part cement and one part sand about 1 in. thick for the ends to rest upon. Use loam to fill in level with the grade so grass will grow. Portable Workbench (Continued from page 100) and 114 in. from the end of the hinged pieces to which they are attached. This simple device works perfectly. When filled with tools, including the heavy vise, it takes all the strength of two men to lift the cabinet, yet when the casters are set in place under it, I have moved it wherever I desired with one finger. In the two years I have been using it, the bench has never failed me. I have made many things upon it—bookshelves and plant stands, several hanging bookshelves, a linen closet, a pier cabinet, and a cupboard (illustrated) for groceries and supplies with shelves above like a Welsh dresser. Drain for Back Yard MAY back yards , or gardens have low spots where water accumulates in rainy § weather. In the writ- 7 er’s case it was the * poultry run which be- came flooded. To over- come this a pit 3 ft. in diameter and 4 ft. deep was dug, and into this were dumped tin cans, bottles, brok- 77 > en crockery, and the 2 Y LN" like. On top of this gravel was piled to a depth of about a foot. The dirt removed from the hole was spread around to raise the level of the chicken yard at a very gentle slope. When the filling settled after several heavy rains, more gravel was added. —H1 S1B.ey. PIT SFT. % 4FT. Sa es at Oz. a Loosely filled pit in center of low area. ® This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. steel makes Simonds Band Saws last longer LL over the country industrial plants use Simonds Band Saws because the steel from which these saws are made has unusual strength, toughness and flexibility. The same heat-treated alloy steel— made in Simonds own steel mills—is used in making Simonds Band Saws for home workshop outfits. Simonds Band Saws are made with the skill and precision associated only with the highest grade cutting tools. The joint is carefully welded —not brazed—and is equally as strong as any other part of the blade. Free booklet on woodcutting saws sent on request. Write for it. SIMONDS SAW AND STEEL COMPANY “The Saw Makers” Established 1832 Fitchburg, Mass. BRANCH OFFICES AND SERVICE SHOPS ‘IN PRINCIPAL CITIES SIMONDS SAWS ES STEEL . awes as fo. OS hUCUCULeelCUS -_- =-—_ ao & Se hw Oe relUrMhelUClClCUrr lUOlUlClUlCUellC ee eS CO

Page 115

LAY, 1999 ls ial ws Fs or a May, 1929 MINI i f p “ SS Repairing Shingled Roofs That Leak Paste this Home Workshop Refer- ence Sheet, including the head above, in your scrapbook in the sec- tion marked roofs. (May, 1929, | POPULAR SCIENCE MONTHLY.) What shall we do with a leaky shingled \ roof? SUALLY the repairing of a leak when found and reached is a comparatively simple matter, but wlien shingles are blown off from different parts of the roof, it is good evi- dence that all the nails are rusted so badly that repairs will be like putting a new patch on rotten cloth. The only logical and economical thing to do is to cover the entire roof, for the cost of repairs will largely be wasted. To locate the leak we must consider the method by which the roof was boarded in. If the roofing boards are strips 214 in. wide as shown in Fig. 1—the method used in many western and southern states—the locating of a leak is not difficult. Go into the attic on a sunny day and push a finishing nail or a sliver of wood through every place where light can be seen or where discoloration indicates that water has come through. This will locate most of the leaks so that they may be repaired from the outside, as indicated in the photograph on page 120. Probably other leaks will be missed, for a split shingle may come over a rafter, or be sev- eral shingles above the place where the water stains show on the inside. Even where no light comes through the overlapping shingles, a high wind may sometimes drive the rain through. One person inside to push the splinters through and another outside to do the repairing make an excellent (Continued on page 120) Three types of shingled roofs, and how a ladder or a ladder board is used for working on them. =. Ep. Ee. Ep. Ep. Ep. Ee. Ee. Ea. Ee ll le | POPULAR SCIENCE MONTHLY 119 hdd ddd id Adil did Now ... your morning shave lasts longer smoother, closer, small-bubble principle gives altogether different shave COLGATE LATHER Colgate’s lather (greatly magnified) showing mois- ture contact with beard and minimum air. A common- sense principle scientifical- ly h ry a dp oved out practically by millions ORDINARY LATHER Ordinary, big-bubble lather (greatly magnified.) Note air-filled bubbles whichcan’tsoftenthe beard sufficiently. Only water can do the job. Only small bub- bles permit sufficient water. T five or six in the evening do you wonder if you'd better shave again—or do you figure on “getting by”—do you hope that others won’t notice? A longer lasting shave is wholly a matter of proper preparation so as to get a closer shave. That means the beard must be properly moistened. Big air-filled bubbles won’t do. Only Colgate small-bubble lather can carry sufficient water to do the job thoroughly. Common sense confirms this principle. Now home-shaving is infinitely easier, for the minute you lather up with Colgate’s, two things - happen: 1. The soap in the lather breaks up the oil film that covers each hair. 2. Billions of tiny, moisture-laden bubbles seep down through your beard . . . crowd around each whisker . . . soak it soft with water. Instantly your beard gets moist ... easier to cut ... scientifically softened right down at the base... then your razor can do its best work. A comparison between ordinary big-bubble lather and Colgate small-bubble lather awaits you, if you mail the coupon below. We will send also, a sample of After-Shave, a new lotion—refreshing, delightful ... the perfect shave finale. COLGATE. Dept. B-1768 595 Fifth Avenue, New York Please send me, FREE, the seven-day trial tube of Colgate’s Rapid Shave Cream; also a sample bottle of “After-Shave.”

Page 116

120 POPULAR SCIENCE MONTHLY | Get this man’s Hammer with the Nail-holder The Cheney NAILER is a real ham- : mer that you will like to use with the added convenience of a mar- velous nail-holding arrangement. The Cheney NAILER has a smooth, slick handle of hickory made with the famous Cheney ‘“‘Never-Slip”’ grip which really fits in your hand; a head of tool steel tempered for hard work; and over all a balance or “hang”’ that is a joy to feel. The wonderful nail-holding device —an integral part of the Cheney NAILER—permits quick and handy one-hand nailing in places far above a two-hand reach. You can set the nail—a nail of practi- cally ANY size—with a single blow; the hammer’s weight is enough to | release it. Ask your dealer for a handy Cheney NAILER which costs no more than any ordinary hammer. Price (1 lb. hammer) $1.50 East of Mississippi Manufactured by PRENTISS VISE CO. 106-110 Lafayette Street NEW YORK CITY 2736 Repairing Shingled Roofs (Continued from page 119) Tin or asphalt patches are slipped under the shingles wherever the leaks have been marked. team for fast work in patching a bad roof. When a roof is boarded with square-edged boards as in Fig. 2, or with matched boards, as in Fig. 3, perhaps covered with waterproof building paper or felt for heat insulation— methods used in the northern belt of states— the locating of leaks is not so simple a proposi- tion. It is not unusual to find, after futile attempts at repairing such a roof, that the leak is several feet above the point where the water comes through inside. Often in locating a leak in the roof of an old house we find the roofing boards were laid from the eaves to the ridge with bearings from three to four feet apart as in Fig. 5. This, of course, gave few nailings, and allowed the boards to spring and vibrate so the nailing was difficult and uncertain. There may be a continuous line of split shingles as at A. The only way to locate leaks in roofs like those shown in Figs. 2, 3, and 5 is by working from the outside of the roof. What is the best and safest way to work on a roof? HE ladder and ladder boards shown in Fig. 8 have stood safety and efficiency tests for many years. They are held in place by a stout hook over the ridge or saddle boards, as indicated in Fig. 4. The shingles are usually so dry and brittle that climbing about the roof is almost certain to split some; hence the ladder and ladder board are not simply aids to climb- A type of construction sometimes encountered; a painted tin shingle, and a shingling bracket. ing, but they reduce the danger of splitting more shingles. Start at the ridge of the roof and work down as far from the ladder as may be reached con- veniently; then climb back to the ridge, move the ladder over, and repeat the process. The roof may be reached by a ladder from the ground or from an attic window. Unless one feels perfectly safe, a light scaffolding may be built, as suggested at A, Fig. 8. The inner end of the ledger B may be fastened with eightpenny common nails driven carefully into the (Continued on page 121) May, Purolato; Oil Filtratiog Gives Your Oil Burn CLEAN OIL UROLATOR, the Oil Filte for Oil Burners, insures , plentiful supply of clean fuel gi and thus eliminates the com, monest cause of all oil burng failures. Dirty oil clogs orifices and valves, wears out pump part and causes excess carbon de. posits in process of combustion, The Purolator Oil Filter stands constantly on guard betwee the oil tank and the burner, It removes from the fuel oil, and holds, all the harmful dirt and foreign matter that would cause untold trouble and expense if allowed to reach the burner, Purolator is standard equip. ment on the leading oil burners, If yours is not Purolator. equipped it is a simple matter to install one—and inexpensive, too. We will be glad to send you complete information. Just write to Motor Improvements, Inc., 352 Frelinghuysen Ave, Newark, N. J. PUROLATOR THE OIL FILTER © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8 May, gue ~— eS a ee ae a wie gc ae ah aha’ >

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May, 1929

—————————————— Repairing Shingled Roofs (Continued from page 120) the casing. Let the heads project so the ils may be drawn easily. Perhaps a neigh- a carpenter may be willing to lend his bordcld brackets. ‘One type of bracket may be supported from the ground by a piece D, Fig. 8. thus eliminating the building of scaffold A, but always guard against side swaying. 4 simple but common type of shingling bracket is suggested in Fig. 7, which is often used on new work. It consists of a piece of “two by four” with shingles nailed to it and held in place on the roof by nails through the shingles into the roof. In a new roof these nail holes will disappear with the first rain, but ona very old roof the nails may split more shingles. edge of What equipment is necessary for re- pairing a shingle roof? HE most important equipment is mental Tin consists of one’s confidence in his ability to do the work and the gumption to make the attempt. The expression of these ualities will require but few tools beside the ladders and scaffolds. (1) A hatchet for trim-

Methods of erecting scaffolds and using roof ladders; the application of chimney flashings. ming shingles and nailing, though a hammer and a stout knife will answer the purpose. (2) A shingle nail cutter or ripper A, Fig. 10, used as in the photograph on page 122, or a notch filed in the back edge of a narrow pointed cutting off saw as at B, Fig. 10, to slip under shingles and cut off nails in the same way. The saw itself will be used in fitting hip and valley shingles. (3) Tin shears to cut sheet metal for flashing and for making tin shingles. (4) A putty knife or an old case knife for apply- ing cement around the flashing. (5) A soldering iron and blowtorch, or an electric soldering iron, if current is available, may be necessary. (6) A pair of ordinary lightweight rubbers or “sneakers” should always be worn while work- ing on a roof, for they greatly decrease the danger of slipping, shingles will not be so badly broken, and it is possible to walk over roofs not steeper than one third pitch. What materials are required for re- pairing a shingle roof? the roof. We shall assume that the roof is in such bad shape in both shingles and flashings that we question whether it will not be better to re-lay the entire roof. For such a roof we shall need: (1) New shingles for replacing those either blown away or beyond repair. (2) Painted roofing tin, zinc, or galvanized iron, or tin cut from tin containers. The last should be painted on both sides and allowed to dry. These sheet metals are to be cut into tin shingles ranging from $ or 4 in. by 5 or 6 in. and are for slipping under split shingles. Pieces of one- or two-ply asphalt roofing of the same size are also used for the same purpose. Provide plenty of these. Such a roof as we have in mind cannot be made

to last more than a (Continued on page 122) POPULAR SCIENCE MONTHLY ” e e e

Your FRIENDS judge you by your home. To them it is an indication of your per- sonality, your pride—your prosperity. And of all the rooms in the house, the bath and kitchen are most apt to be neg- lected —drab—dreary. Now these rooms may be rich in color— new in beauty, smart in appearance—by the use of Upson Fibre-Tile at about one- tenth the cost of ceramic tile. Your carpenter can apply the big, sturdy panels right over the old surface with little muss or delay. Or add the extra bath, so needed in the average home.

[Hs depends largely upon the condition of The panels of Upson Fibre-Tile have deep tile-like indentations and come unfinished, 121 CHEERY COLORFUL TILING gives new life and smartness to bath, kitchen, laundry or nursery

Transform that oft neglected bath or kitchen— Cover the sprawling, crawling cracks of old plaster with Upson Fibre-Tile and Upson Board! Give new charm—warmth—< character to these rooms. so you Can paint or enamel them in bright, joyous color. Certified tests prove Blue Center Upson Board and Upson Fibre-Tile excel in resist- ance to jars, blows, heat, cold and moisture, as compared with other boards tested. You will like your Upsonized rooms. Tens of thousands of satisfied home owners have solved their wall and ceiling problems for all time by Upsonizing. Nothing is handier about the house than a few panels of Upson Board. You will find dozens of uses for it—for screens, table tops, tool racks, hampers, sewing boxes and count- less other articles We invite you to mail the coupon today. UPSON BOARD and FIBRE TILE

eas oe rrentihig ge TNs

The Upson Company, 527 Upson Pt., Lockport, N. Y. Enclosed find 10 cents for which ow send me copy of your new booklet, ‘‘Characterful Walls and Ceilings,”’ samples of Upson Board and Upson Fibre-Tile and details of your new Decorative Service. Iam interested in 0 New Ceilings ‘ [ Office Interiors C0 Tiling ba Street. - SZ City and State - © 1929, The Upson ( Company, Lockport, | N.Y. Name

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NEW Basement Walls That You Can Brush On rN a Ei ET oe =e a eet seer cdinaer ene SOI ae — FE RAE SS SSS oy WO coats of Medusa Port- land Cement Paint on a basement wall actually gives you a new, white, concrete surface. Unlike other paints this one becomes an actual part of the surface on which it is placed. There is no lime, glue, or casein in Medusa Portland Cement Paint, and it is not a Gypsum product. The base is Portland cement. Properly applied it will last forever. May we send you complete information? MEDUSA PORTLAND CEMENT CO. 1002 The Engineers’ Bldg., Cleveland, Ohio Manufacturer of Medusa Portland Cement Paint; Medusa White Portland Cement (plain and water- proofed); Medusa Gray Portland Cement (plain and waterproofed); and Medusa Integral Waterproofing. MEDUSA re MEDUSA PORTLAND CEMENT CO. 1002 The Engineers’ Bidg., Cleveland, Ohio I want to know more about basement walls that can be brushed on. Send complete information on Medusa Portland Cement Paint to:— POPULAR SCIENCE MONTHLY Repairing Shingled Roofs (Continued from page 121) few years longer, hence these will last until the entire roof must be relaid. Also necessary are copper or tin for repairing flashing, fourpenny shingle nails, and a few eightpenny and ten- penny common nails for nailing flashing into the chimney. (3) Often upon a repair job the liberal use of asbestos or elastic roofing cements will do well enough as a makeshift for repair- ing flashing instead of using solder. (4) Solder and fluxes—muriatic acid cut by dissolving in it as much zinc as it will take up, for use upon galvanized iron or zinc, and rosin for use on tin. How are leaks in a shingle roof re- paired? 1 A SPLINTER of wood pushed through ¢ the roof from the attic and showing as at A in the photograph on page 120 requires that a tin shingle or a piece of asphalt roofing should be pushed under the split shingle until it is out of sight. The upper corners of a tin shingle should be turned up.a little as at A, Fig. 6, which will hold them in place. Asphalt shin- gles will melt enough the first hot day to stick to the wood shingles and stay in place. 2. Other shingles may be split as at B in the photograph last mentioned. Even if they do not leak at present, preven- tion is the policy, so we will slip a tin or an asphalt shingle carefully under the split. 3. Some shingles may have been blown off or badly split. These may be replaced with new shingles. First cut off the nails of the shingles just above the splits by using the ripper. This will allow the split shingles and those around them to be removed easily. Usually a quick pull with the hand will cut a nail, but if not, a hammer or hatchet may be used to strike the ripper. Lay the new shingles to conform to the courses, nailing them not less than 5 in. from the butt, and break joints at least 34 in. with the joints in the course immediately below. One objection to the use of new shingles is the color contrast between them and the old roof, which gives the roof a freckled appearance. This may be helped by bringing the new (Continued on page 123) (> Drawing nails with a shingle “‘ripper.”’ SHINGLES A ALL THE ME. COURSE FIG. Some of the tools used in making roof repairs, and a diagram of a typical shingled roof valley. Not “in the bag’ Andrew J. Pi emphatically i nies the rumor that his recent dis. astrous contest with a Trimo pipe wrench was “in the bag.” “I know that I made a miserable s i but I want all pi lovers to know I did my best. “This new Trimo has a vicious grip and an ugly disposition. In fact it makes me feel a little shaky just to think about it.” The day when a stubborn pipe or nut could put u a winning fight is one now. Trimo, mproved and Mightier, makes ’em all say ‘uncle,’ Look over the rug. ged frame, heat treated handle, business-like jaws — what chance has a pipe got with this all steel wrench ? TRIMONT MFG. CO., Ine. Roxbury (Boston) Mass. RIMO IMPROVED and “MIGHT! @ This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. Pipe Wrench leceupresae@

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» ag . Pj lly "umor ent dis. >ntest 10 pi as nee I made en a at up and akes nele,’ heat dle, vhat May, 3 May, 1929 ee Repairing Shingled Roofs (Continued from page 122) . ut the same color as the old with inte Si Gaskéd ht dad hanpention, tall " d half, with a little japan and dry color— iar black or burnt umber. Asphaltum thimmed with turpentine will serve the same urpose. By the time the stain has disap- P the weather will have so equalized the colors that the repairs will be noticed by few. 4. Do not drive shingle nails so hard that the heads of the nails sink deeply into the wood, for this will break the wood fibers and may later split the shingle. Drive them until the head rests lightly but firmly on the shingle. 5. Often in repairing hip or valley shingles, tin or asphalt shingles will be all that is neces- sary, but if new shingles are required, use care in removing the old ones in order to see how they were fitted and laid. Valley shingles should be cut from the part of the shingle where the thickness is the same as the rest of the course, that is, the thin or top end of each valley shingle should rest on the same hori- zontal line as the rest of the course to keep the thickness of each course the same until it is finished at the valley, as at A, Fig. 11. Be very careful that no nails are driven into the flash- ing lower than necessary, say one inch from the top edge of the flashing, or a bad and invisible leak may result. Hip shingles rarely give trou- ble, as the water runs away from them, but if any have been blown off or been badly split, the method of re-laying them must be governed by the way they were laid originally. How may leaky flashings be repaired? riage and their metal flashings are so closely related that they cannot well be con- sidered separately. Often a surprising amount of rain water will find its way through a rust hole no larger than a pinhead. Though a few such holes may be mended with solder or roofing cement, if the flashing appears to be rusted through, it may be economy to tear it all off and reflash. 1. Usually if leaks appear within 4 in. of a chimney, it is safe to assume that the flashing is not doing its duty. Unless the leak can be reached and repaired without removing the shingles, they will have to be taken off and perhaps the entire flashing relaid. Begin at the top and notice how the work was done in the first place. Duplicate it with care, espe- cially the method of joining the shingles and the flashing. While this work may be worth avoided upon a shingle roof if possible. 2. Usually a careful and liberal puttying or doping with asbestos or elastic roofing cement, or a little judicious soldering and the use of tin or asphalt shingles, will cure any leak in flashing not more than twenty years old, if it was well laid in the first place. 3. A leak or a prospective leak may be located by pressing against the suspected point with the finger or the point of a nail or jack- knife. If a firm pressure breaks through, the metal should be repaired. In any case the counter flashing A, Fig. 9, should be plenti- fully recemented and nailed with flashing nails or eight- or tenpenny common nails, for their heads will hold flashing to the brickwork very well. Drive them slantingly and they will hold better. 4. Owing to the difference in the expansion and contraction of the roof and of the chimney corners, the flashing at B and C of Fig. 9 may Tequire resoldering. If flashing leaks are not too bad, a coat of heavy roofing paint or canvas bedded in roofing paint may be sufficient to keep the water out until a new roof becomes imperative. After the flashing of an old shingle roof has come to need repairing, it is seldom good economy to spend much money in repairing it; usually the simplest repairs will extend its life until a new roof must be laid.—C. A. K. while upon a slate or asphalt roof, it should be | POPULAR SCIENCE MONTHLY Motorcycle shown above is our latest model, the “45"—a Twin priced at only $290 f.0.b. factory. on meme + a LAN, Now, on a wonderful vacation by motorcycle. Take that trip you have long promised yourself —see more of America! Glorious roads spread out in every direction—for you and a Harley-Davidson to enjoy. Cities to see. Lakes to sport in. Mountains to climb. Ad- ventures to meet. With a Harley-Davidson you can GO THERE, for the cost-per-mile will be only a penny or two! Let your local Harley-Davidson Dealer prove this to you. Ask about his Pay-As-You-Ride Plan. And mail to us the coupon below. Smita Cl Th a HARLEY-DAVIDSON MOTOR CO., | Dept. P.S., Milwaukee, Wis. i I Send me FREE illustrated literature on your motorcycles. z ame. Address My age is [) 12-15 yrs., [) 16-19 yrs., 20-30 yrs., | (0 31 yrs. and up. CHECK YOUR AGE GROUP. a

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© eS EC — | SRS SOE IE PS ed POPULAR SCIENCE MONTHLY N oR RODUCTION OY LAP, Newtinr ROOT SMALL RESET RATCHET COUNTER This machine turns out one to two thousand tapped pieces pet hour. Not a one escapes reckoning on the dial of the Counter. There is the record—always in front of the operator, urging speed! Let the work slow down, and the fact goes down on the Counter. It’s a warning to the operator to get busy. What a spur to production —at any machine! Either in operating or developing machines, you can set up records to aim at—and beat! \ Anderson Dial Feed Tap- ping Machine, recording its Output automatically. When the work’s done, it’s counted. Price of Re-Set Ratchet Counter illustra- PARKS WOODWORKING MACHINES Write for Veeder-Root bul- letins showing Counters for any machines you imay need them on. All are eligible! You can equip your other prcduction machinery to make high records auto- matically, Write for book- let showing Counters for all product- recording purposes. $290 with Motor You ought to have this handy Parks in your shop. Compact, } complete machine de- signed like a big production outfit at 1/5 the cost. Floor space required only 42x72 inches. Does any kind of cabinet or joinery work. Write for circular. The Parks Woodworking Machine Co. 1547 Knowlton St., 5 ian Factory: 338 Notre Dame East, Montreal All Separate Machines in Boice’s Wactenope!”r Tres, individual | Home Workshops Workshops! ‘Three individual machines—not mere attachments Compare Boice’s worksh with others for size, capacity and price! On the one illustrated, hundreds of jobs can be done with the saw, jig ~—each separate and complete in saw, lathe and the three books of designs it includes. itself. Always ready to do three Universal Handisaw. Table 15 x 17 inches tilts 45° for beveling. different i, wanes. jig_saw- ing and lathe turning. Heavy 9-inch saw cuts stock 2 1-2 inches thick. Equipped for dado heads, cope heads, sand disc and duty motor gives , plenty of power. saw table, scroll, ie and bandsaws, and all acces- sories for drilling, buffing, grinding and cleaning. Attaches to light socket and gives you private ma- chine shop. ONLY $10.00 DOWN. , ‘ Free Crafts Course and Blueprint Service Y Send Coupon for Interesting Literature. oo jointer attachments. ' ¢ Utility Lathe has 8- inch swing, 19 inches Cc r, Handi- Send 10c for new * 1929 catalog of 80 pages. scribes complete line of 15 different __ Boice - Crane Machines and be beaten for prac- ticability and low cost. We also make 12-inch and 14-inch Band Saws and 4- inch Jointers. W. B. & J. E. Boice A Model for Long Flights (Continued from page 81) lower sidepiece. Paper the fin and treat with light dope. It should weigh betwen and .06 oz. a The propeller (Fig. 5) as made h Shifle. Smith was in two pieces. You can, howe use a standard type blank such as scribed in connection with the Morris in the March issue of Poputar Monta y, the blank being 34 by 134 by igi, By using two pieces, however, yoy a considerable balsa and also are assured that the shaft will be properly located. Th thy case, use a blank 34 by 13¢ in. (plus the wid, of the saw which you expect to use in gayi the blank apart) by 81% in. Cut the ble. diagonally in two as shown, and with ruler ay), pencil scratch a small groove for the p; | shaft 14 in. from the narrow end. Do Po a each piece. Make the shaft of No. 13 music wire, 1 in long, as shown in Fig. 6, and lay it in th groove. Anchor the U-bend in the balsa woo) Cement the two halves of the blank togethy and allow them to dry for several hours in, warm place. Next carve the propeller, which should hay a 32-in. pitch. At the hub it should be \ in thick; at the tip 14 in. The hub should be i in. from front to back when completed. Roun the tips as shown. Give the propeller four or five. coats ¢ banana oil and an extra coat or two on th entering edges and tips. Sandpaper the blade very lightly and check the balance after each coat is dry. Even a slight error in i will cause the model to vibrate and fly ip efficiently, if at all. If your propeller weigh about .12 oz., you may consider that you have done a good job. The motor consists of ten strands of fresh #z by \% in. flat rubber, which is what Shifle. Smith used on his record flight. It should weight about .75 oz. Make the S-hook of No, 13 music wire as shown in Fig. 6. To assemble the model, slip two washers on | the propeller shaft, with a minute drop of ail between. Thread the shaft through the bear. ing, slip the motor through the cans, and fasten the S-hook to the rear hook. Insert the fin and balance the machine on your finger. Slip th wing clips on the motor base so that the enter ing edge of the wing will be about 1 in. i front of the balancing (Continued on page 125) Materials for the Model 1 pe. %& by \% by 45 in. balsa for motor stick. 1 pe. % by % by 45 in. balsa for motor stick cap. 1 pe. 1/20-in. balsa veneer for ribs and false ribs. 1 pe. }%-in. balsa veneer for center rib. 2 pes. #s by 3 by 16 in. balsa for entering edges. 2 pes. 6 by 4 by 16 in. balsa for wing beams, front. 2 pes. '% by % by 16 in. balsa for wing beams, rear. 1 pe. % by 1s by 8} in. balsa for propeller blank (or for a one-piece propeller, 34 by 1% by 16 in.). 2 ft. No. 11 (.026 in. dia.) music wire. 2 ft. No. 13 (.031 in. dia.) musie wire. 2 sheets superfine Japanese tissue paper. 1 2-oz. can ambroid type cement. 1 2-oz. bottle of pure banana oil. 1 2-02. bottle of light dope. 1 drilled bearing suitable for use with 10-strand rubber motor, or a small nail from which to 2 small washers. 38 ft. %-in. flat rubber. | make this bearing. 2 yds. fine silk thread. Several long strips of bamboo (more than 12 im between joints). | t a @ This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8

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ck. stick eller y 1% ‘and May, 1929 POPULAR SCIENCE MONTHLY A Model for Long Flights (Continued from page 124) . ‘ht the model to see that the fin is poi eh vertically and lengthwise, and ae the wing has a slight additional angle in the right half. aa Glide the model by launching it on an even keel at about its estimated flying speed; do this in a place where the model will not be damaged upon landing. If it dives steeply, e wing forward; if it stalls and then wnward, move the — to the sare: model glides at a uniform angle to bageeoner without stalling, the wing is approximately in its correct position. As a final check before flying your model, weigh it and see how closely it approximates Shifler-Smith’s model, the flying weight of which was 1.82 oz. With a regular 5-to-1 egg beater” winder, put from 140 to 160 turns in the rubber. You will probably need someone to hold the propeller and steady the wing tips. You understand, of course, that the S-hook is removed from the rear hook and hooked on the winder and that the rubber is stretched out at the beginning of the winding operation. Gradually shorten the rubber as you wind until it is about the length of the motor base. Grasp the S-hook firmly, remove it from the winder, and hook it into the rear hook of the model. You may find it convenient to remove the fin while winding. See that the rubber is evenly distributed along the motor base or it may catch slightly on the rear cans. This is very important in tractor models. If the model is well adjusted, it barely climbs for five or ten seconds but then starts on a long, gentle climb. If the model climbs nicely at the very beginning of the flight, it probably will be overelevated at the end and there will be some loss in duration. Mark the adjust- ment points very closely and number them so that they can be located again. Even ¥-in. difference in the wing location makes an ap- preciable difference in the flying qualities. If the model circles to the left with the inside wing low, you will have to put more incidence in the right side of the wing. If it swings to the right and then to the left and back again to the right, it is an indication that you have too much incidence in the right wing. For a contest or record flight the motor will stand from 230 to 270 turns made with a 5-to-1 winder. A 15-in. propeller with about a 30-in. pitch may come in handy for flying the model in a fairly stiff breeze, but extreme care should be used in handling the wing on a windy day. A box for holding the model and the necessary extra parts and tools will be found useful. move th zooms do Hammered Metal Bowls (Continued from page 79) every metal working operation, I have found it an advantage to keep the metal thoroughly clean as I worked it. Place the disk centrally over the hollow in the block as shown in Fig. 7. Hold it firmly in position with the left hand and bring the ham- mer down on it, so that a dent or boss is made. Then move the disk slightly to one side of the center and strike another blow at the edge of the hollow made in the metal. Now continue around the edge of the hollow, moving the disk to convenient positions as you hammer. Con- tinue hammering in a spiral fashion, making the blows come close together to stretch the metal down evenly as you work gradually nearer the edge of the disk (Fig. 4). Any flutes that appear on the edges of the disk should be hammered down as they occur. _ While this process of making a bowl is very simple, care must be taken to keep the form Symmetrical (round) as the bowl is being worked. Look it over (Continued on page 126) ” Ss Planning high-speed business An Advertisement of the American Telephone and Telegraph Company More than 95% of the tele- phone calls from one town to another in the Bell System are now on a high-speed basis. This holds whether the call is from New Orleans to Boston or from New York to Oyster Bay. Even if it is a long call, the oper- ator in many cases now asks you to hold the telephone while the call is put through. Calls from one town to another used to be handled by one operator taking your order and giving it to another group of operators to put through. You now give your call direct to the operators who put it through — and put it through fast while you are on the line. The average time for handling all toll and long distance calls in the Bell System was further mate- rially reduced in 1928. A high-speed service to all parts of the country—calls from one town to another as swift, clear and easy as local calls—that is the aim of the Bell System. This is one of the many improve- ments in methods and appliances which are constantly being intro- duced to give high-speed telephone service. Better ‘and better telephone service at the lowest cost is ever the goal of the Bell System. “Tue TELEPHONE BooKS ARE THE DIRECTORY OF THE NATION” BUILD A WORLD RECORD TRACTOR MODEL AIRPLANE Kit Son genuine Shifier- Smith model channel spar & cap, metal » ex ssue, wil ’ i. Only $2.50 or $3.35 with carve ‘ie-in. propeller, postpaid. Send order now! No C. 0. D. Everything for the model aviator at lowest prices Send 10c for List of Quality ins from The Home of P mere Models Clubs, Schools, Dealers . . . Write for terms PERU MODEL AIRPLANE SHOP, Dept. P., Peru, Indiana A SHIP MODEL FOR $4 98 Build the historic Santa Maria LaPinta or the Mayflower. We send postage. No tools needed except a = small hammer. F Parts for model of Constitution sent C.O.D. for $6.98, plus postage. Write for illustrated catalogue. MINIATURE SHIP MODELS, INC., 3216 Baring Street, Phila., Penna. ANNOUNCING SPORS GUARANTEED NO. 1 PEN Use 60 Days SELLS FOR $1.25 SEND ONLY ——_«~ IfNot @ 39° ES: F. SPORS & CO., 329 FRANK ST., LESUEUR CENTER, MINN. WRITE FOR FREE WHOLESALE CATALOG SHOWING OVER 400 ARTICLES

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r _ a el tL RE GI II

When you think of shaving think of Aqua Velva for After-Shaving! Let Aqua Velva start your summer with you. There’s real pleasureofasummer morning in its stimulating thrill! Profit,too,inthatit cares for tiny nicks, cuts, abrasions— unseen, mostly. Tonesup. In- vigorates. Makes facial tissue firm. Protects from dust and germs. Helpsto takethe sting from sunburn (though doing nothing to prevent a ruddy tan). Made by the makers of Wil- liams Shaving Cream, Aqua Velva keeps the skin as the super mild, super moist Wil- liams lather leaves it, flexible and Fit! Start your summer with Aqua Velva. Remarkably worth while! 5-oz. bottle 50 cone at all dealers, Or a Free Trial Size b pedoessing: Dept. PS29, The J. B. Williams C Glastonbury, Conn.—Montreal, Cone’ a. Williams | Aqua Velva For use after shaving POPULAR SCIENCE MONTHLY

| Hammered Metal Bowls (Continued from page 125)

END OF END OF SECTIONAL VIEW SIDE OF SIDE OF BLOCK TOOL BLOCK TOOL Fig. 7. Plain block used for making bow's, and shaped block and tool for decorating them. | carefully after each annealing and straighten | it up before hammering further on it. If the | —_ gets too much out of shape, it is almost | — to make a good job of it. ter you have hammered over the entire surface of the bowl, you will have a shallow saucer shape. Anneal the work, pickle it, scrub | it clean, dry it, and then start to hammer it | in the center again, working out to the edge | in a spiral of hammer marks. When you have stretched the bowl form in the center to the | depth you wish, hammer around and around | where you wish to enlarge or deepen the sides, starting a slight distance from the center to stretch the metal down to form a base for the bowl (Fig. 3). If you wish the sides to project more than the top or rim, hammer around and around just inside the rim to stretch the metal; always, of course, keeping the metal well annealed until the last hammering, after | which it is not annealed, as it is desirable to | leave the bowl “hard hammered” so that it may not easily be bent out of shape when finished. You will learn to govern the strength or force of your hammer blows so that the metal is hammered down evenly and smoothly where you wish. All these bowls should, of course, have flat bases to stand on. A base may be formed in two ways. One method is to hammer the metal at the base of the bowl so that in the end it is stretched down flat. The metal may be still further flattened by (Continued on page 127)

Fig. 8. How the bow! and shears are he.c when trimming away the excess metal at the edge.

Good as New are cracked walls and ceilings when mended — with Rutland Patching Plaster, — You can easily do it yourself in a few minutes. Just mix with water, then fill the crack or hole, Makes a perfect patch that is permanent as the wall itself. Ag all paint, wall-paper and hard) ware stores. Rutland .Fire Clay Company, Rutland, Vermonty Rutlan< Patching | Plaster |

DUVROCK PORTABLE Tk! of o S we aa JON Sy” TRAPSHOOTIE 9) Te , Wherever Youth AN fits eae weight, com matic, Ideal for camp, farm, aboard yacht. .forevey outing. Slips easily into yor soace. Aine recdr tena space. Always ready ———- ond ae Fire n groun: irds fly feet in any desired Self Loading 43 birds = 16 seconds...or# Automatic slow as you wish. Sturdy struction...nothing to break or wear out. Heavy Du» enamel finish. Weight 10 1-2 lbs. Trap comes complet with Duvrock MOLD for Making Your Own Birds A ootantes on new Bird Mold that tarns out Derfoct i samp b simple formula ether Mol yond compie Birds, a Lng 00, ‘oney bac May for this coe oy trapehooting outfit. ..ma DUVROCK BIRDSm hasedin ns of 500.559 5 oe cartons Weight S6 ibe, Hinsteatet Trap: ra folder one puvacce CO., 245 S. Main & Sa Los os Angles, 0 Please ship me DUVROC I (including MO: and 100 Rea). PORTA! 26

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May, 1929 Se Hammered Metal Bowls (Continued from page 126) : bow! right side up on a flat anvil —_ ja hammering it with a round wooden i flat end. ; om ee eal somewhat simpler method is to hammer the bowl in a regular rounded bowl either with no base or with a moderate flattening at this part. When the bowl is ham- ered to a suitable depth, place it upside down - a flat surface, find the center of the bottom, tae seribe a circle of the diameter it is desired oe make the base. With the same embossing hammer used to make the bowl, tap gently in the center until this sinks down below the base line and then hammer around and around this, working out to the base line, as shown in Fig. 5. To trim off excess metal at the edge of the bow! after a base has been formed, set it up- right on a flat surface and scribe a line with a surface gage around the edge parallel to the pase.and starting at the lowest point of the irregular edge (Fig. 6). If you have no surface . a good substitute may be made by driv- ing a wire nail in the side of a square block, Fig. 9. Using a wocden forming block and tool to decorate the bow! shown in Fig. 2. cutting off the head of the nail, and filing a sharp point on it. The point may be bent up or down as desired. About the only way to trim off excess metal is shown in Fig. 8. Hold the bowl in the left hand with the open part toward you. Use a pair of straight shears and cut from right to left. If you have much metal to cut away, do not try to do so all at once, but cut off a nar- row strip as you go around the edge, finally cutting carefully down the line. A flat file is used to smooth up the edge. Sometimes a small bowl may be placed up- side down on a sheet of emery cloth placed flat on the bench and the edge rubbed smooth. When the edge is smooth and flat, round it over with a half-round file and emery cloth so that the bowl will be pleasant to handle. Never leave sharp edges about your work. _ Figure 9 shows the process of making a bowl into a chalice or flowerlike form. After the bowl is hammered to a smooth shape, a wooden block is made as shown in Fig. 7. The end of this is filed with a wood rasp to fit the curve of the inside of the bowl, and then a fairly broad groove is cut or filed across the center of it. A wooden tool, shaped like a blunt cold chisel, is then made of hardwood, as shown in Fig. 7. The bowl is divided up in as many divisions as desired with pencil lines, not scribed lines. The block A is held in the vise, the bowl is rested on it, and the wooden tool B is used to drive the metal down into the groove in the block. POPULAR SCIENCE MONTHLY 9” x 3’ Junior Back Geared paras, Cutting Bench Lathe with Counte: $ pa one 155 te Prices of 9-inch Junior Lathes Including Lathe Equipment - Size of Shipping Counter- Lathe Weight t 9"x3’ ; $155.00 $226.00 97x34’ 400 Ibs. 160.00 231.00 9x4! ; 165.00 236.00 EASY PAYMENTS as Low as $12.40 a Month © Our Easy Payment Plan allows you to install a South Bend Lathe in your shop, by making one pay- ment with the order; the balance to be paid month by ff month, the amount depending upon the size of lathe. }} Write today for Catalog No. 89-P which describes | Easy Payment Plan. Mention size of lathe desired. 18” x 8’ Quick Change Gear Sifent Motor Driven Lathe......... Sees Prices of Popular Sizes of Quick Change ear Lathes with Equipment Shipping Weight 490 Ibs. 725 Ibs. 335.00 1110 Ibs. 402.00 1550 Ibs. 490.00" 2035 Ibs. 570.00 Counter- Size of - shaft South Bend Lathe Works 822 E. Madison St., South Bend, Ind.,U.S.A. , New York City, J. E. Beggs Co., 183 Center inhaled en 4 chalt Drive. Some ttes Silent Chain Drive Motor Drive 00 yoo 5.00 7 ie i i es fo BRO Shows how YOU Can Make « Fine Clocks Right at Home Money - Makin, HOUSANDS of menhave ideas. Gives ful built our Clocks. For details, their own use—or to sell movements and ®t money-making prices. It’s porte. Weite BOW easy, fascinating. Only ordi- or your copy nary tools needed. We furnish plans, instructions, parts. Works all assembled, ready to install, as low as $1.65; others with chimes at all prices. You make the case, or simply as- semble knock-down parts. Cash-in on the demand for craftsman-built Mantel Clocks, Ban- jo Clocks, Grandfather's Clocks. Here's a hobby that PAYS—in pleasure, in ownership and _ in spare-time or full-time PROFITS! Write for FREE Catalog and Special Blue Print Offer AMERICAN CHIME CLOCK COMPANY 1691-E Ruffner St. Philadelphia, Pa. A New Lightweight Electric Drill Sturdy and ae. Fully teed for ¥ ially desi for light and intermittent work. Wei only 4 Ibs. or money ord be refunded. In be sure to and money J WHITE FOR OUR CATALOG, Jones Motrota Sales Co., Dept. 305, 370 Gerard Ave., N.Y. © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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=

Made For Heavy Duty E demands put upon modern liners require unusual strength and rug- gedness of both hull and machinery. Screws that will stand up under severe conditions at sea are im- portant items in the specifi- cationsofmarine engineers. Because of easy insertion and great holding qualities under strain, American Screws have always been favorites. They are con- stantly on the job holding wood to wood, wood to metal and metal to metal. You can get American Screws from any hardware dealer — ask for them by name. git" Tip & z ‘ % 2 == wooo MACHINE stove Ter SCREWS SCREWS BOLTS BOLTS AMERICAN SCREW CQ PROVIDENCE,R.I..U.S.A. e WESTERN DEPOT,225 WEST RANDOLPH SL.CHICAGO.ML, Fut lt Together With Screws’ —_

POPULAR SCIENCE MONTHLY

How to Make an Old Style Tool Post More Rigid of up-to-date design. to other machinists. slide. has to be taken. portion of the T-slot and bored as indi- cated by the dotted lines in the assem- bly view. The smaller bore is a working

RECTANGULAR SHAPED BLOCK FITS T-SLOT

atl! “e TWO-PIECE BLOCK BRAZED TOGETHER Lathe tool post improved by the addition of a special bearing block at the lower end. CROSS SLIDE OF LATHE tool post; the larger bore is a working fit on the enlarged head of the tool post, which is cut down to leave a narrower flange as shown by the dotted lines just mentioned. In making the block, two pieces of flat, cold rolled steel are used, which together form a piece wide enough to fit the T-slot. These pieces are lightly brazed together at the ends to hold them in alignment while the boring is done. Afterwards the pieces are separated: by grinding away the brazing. Then the joint between the two pieces B is prepared for welding, placed about the tool post A in position for use as at C, and welded. When the improved post is fitted to the T-slot, it is ready for use. This construction gives a full bearing between the tool post and the welded block and also between the block and the edges of the T-slot, thus making a very durable job.—Epwin KILsurn. Test for Ground Holes against the back side of a hole until the sparks. This test, applied when the hole is nearly to size, may prevent spoil-

ing a job.—H. J. C. The form of tool-post construction used on many engine lathes is such that there is a rather poor bearing between the round lower end and the T-slot of the Because of this limited contact the edges of the slot often wear away or break, and it is difficult to keep the tool post in position whenever a heavy cut A block is made to fit the wide lower it just sparks, then traversed the length | of the hole, it will show whether the hole | is perfectly straight by the un‘formity of | ie THE accompanying illustration is shown a lathe tool-post improvement that has- been found satisfactory on lathes not fitted with a tool-post block As the improve- ment is easily made, it may be helpful fit on the small lower portion of the |

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F THE grinding wheel is brought |

MODEL AIRPLANES That Fly—Only $1.50 Complete BOYS e Here’s the greatest value you've * ever seen. A ame aluminum model airplane that really flies, ata e. The “Mocar” monoplane—Set No. 1—is& copy of Lindbergh's famous Spirit of St. Lowls. Wing spread 18 inches, fuselage 12 inches, erful motor, s al propeller, rubber-tired dise wheels. Weight complete only about 2% 04. This is a practical, simple, real model plane that gives you a whole lot of fun at a very mot erate cost. The all-metal construction makes of abuse, The outfit is mounted on cardboard with all parts plainly marked and full instruction _for assembly. ers only tool necessary. Co struction Set No. 1 complete with rivets, bolts, wheels, wing and fuselage covering mai only $1.50 postpaid (3 for $4.00). Model L made up ready to fly $2.25 (3 for $6) postpaid. Great fun, learn how to make and fly

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ef; HE iH Hig: a3 & May, 1929 POPULAR SCIENCE MONTHLY iin of Men in the Public Eye (Continued from page 20) ining properties in this country pay Aes gy seine at Harvard, Yale, Columbia, and Johns Hopkins Univer- sities. In 1911, President Taft appointed him special ambassador to the coronation of King George of England. The following year he again went to Europe as president of the Panama-Pacific Exposition Committee. From 1914 until 1915 he was chairman of the World Court Congress, and he served in the same capacity with the United States Coal Com- mission from 1922 to 1923. He now lives in Washington, D. C. Magician of Chemistry OT long ago a client of Arthur D. Little, N chemical engineer of Boston, was discuss- ing the uselessness of a certain raw material. “It’s a waste of time to bother with that stuff,” he said; “you cannot make a silk purse out of a sow’s ear.” “Qh, can’t I?” was the reply of Little. Today a red and blue purse, for which the artificial silk was obtained by Dr. Little and his associates from the gelatin and tissues con- tained in a female pig’s ear, is the star exhibit in the museum connected with the concern. In a sense, that little purse is the symbol of Arthur D. Little’s genius of accomplishing the “impossible” through industrial research. Among his recent amazing developments are processes for the manufacture of vegetable glue from starch, the recovery of turpentine and resin from yellow pine stumps, and the extrac- tion of zinc from complex ores. Dr. Little has worked out more processes of paper manufacture than any other chemist in the world. Only lately he developed a practi- cal method for making newsprint paper from Southern woods. When operated on a large scale, it promises an enormous reduction in the cost of newsprint. He is the inventor of processes for the manu- facture of chrome-tanned leather and artificial silk, and has directed the production of a long line of alcohols and special products from petroleum. Dr. Little is now sixty-five years old. His interest in chemistry began more than half a century ago, when he was a public school boy in Portland, Me. One day a boy seated back of him in the classroom nudged him and whis- “Arthur, have you a dime?” Little inspected his pockets and discovered just ten cents. “Lend it to me,” the boy whispered again, “and after school I'll show you some chemical experiments!” Young Little made the investment. With the dime, the boys bought a piece of glass tub- ing and five cents’ worth of sulphuric acid. For the first time, Little saw sulphuric acid react- ing upon zinc and producing hydrogen—but he heard it, too! The generator had been im- properly set up and exploded, but without damage. That evening he informed his parents he was going to be a chemist. They sent him through preparatory schools, and later enrolled him in the Massachusetts Institute of Technology. His first job after leaving college was that of part chemist and part clerk with a paper mill near Providence, R. I., at two dollars a day! Six weeks later he was superintendent of the mill, which was the first in this country to make sulphite wood pulp, and when he quit, his salary was $2,200 a year. But he wanted to be his own boss; so, with another chemist, he started a consulting chemists’ laboratory in Boston. The Little laboratory was on the sixth floor of a dingy building in a little side street and its equipment was scant. (Continued on page 130) 129 MAKE THIN echnical 6s g IURE, —.* Patented Jan, 2, 1929 Designed for Efficiency in Operati Practical craftsmen appreciate this man-sized, motor-’ oe ized workshop with its carefully planned, efficient de- sign. The “Delta” is equipped with a smooth-running, powerful, two-shaft motor. Permits ing on two | or three important operations at one time without) continually dismantling set-up. Much-needed Circu- | lar Saw available 90%. of the time! Also has heavy Triple Foundation Lathe. Bed (no rods), guaranteed not to chatter; Improved Patented Tilting Tables on = >— Circular Saw and Sanding-Disc; Automatically Oiled —_—- Bronze Bearings. Comes completely assembled, thor- ©; © "= oughly tested, on heavy veneered Wooden base. Many || new exclusive features in 1929 model—new low price Enjoy the thrill “Working | ¢ with Quality Machinery | Make the things you have always wanted to make, with this - . sturdy, full-sized equipment. Save money on repair work— earn money in spare tinie. It is so easy—so quick, with the ‘Delta.’ Complete Handi-Shop includes all necessary equip- ment for Circular Sawing, Wood Turning, Scroll Sawing, | Sanding, Drilling, Grinding and Buffing. Full instructions | and complete set of working ints furnished. f Fasy lerms D Pia Without obligation, you can test the Handi-Shop actual conditions for 10 days in your Send at once for FREE illustrated literature, description of the new. 1929 Model “Delta” ; i and full details of 10-Day_ Trial © B-59 Pe eae reed | en keritee setts raperurs & Delta Ye peci a Ity O, | tator20 Day Triat Offer and Easy Payment Plans 1661-1667 HOLTON STREET | ™™*- MILWAUKEE, WISCONSIN _ Perm atti ote | © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. 50 POWER" MICROSCOPE OWN this fine, labora- tory type instrument... as ; same used by Scien- pF tists, Physicians, Den- pees tod tists’ and professional Physicists. Has ment and the uick adjustment by knurled nuts both fascinating new in- sides of tube. Special device protects # struction methods. No slides from breakage. Triple divisible long drudging over scales. objective gives different powers and large, clear field of great depth. Square stage with clips. Adjustable iris dia- }% phr , with plane and convex 3 mirrors. Adjustable stand. A -— precision microscope complete with handsome case. Save money... buy direct—money refunded if not absolutely satis- fied after 30-day trial. Send check, money order or Conn gives you the exclusive features found in no others. Choice of famous artists. FREE TRIAL, Easy Pay- ments. Write now for liter- ature; mention instrument. Cc. G. CONN, Ltd.. 532 Conn Bldg. Elkhart, Ind. T Conn

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130 POPULAR SCIENCE MONTHLY May, 19% machinery! Te Manager Dept. No. 33 UP-TO-DATE MACHINE WORKS 2915 So. Wabash Ave., Chicago, Ill. UP-TO-DATE HOME CRAFTSMAN SHOP For. the handy man or boy who enjoys working with well equipped electrically driven wood working The Up-To-Date Home Craftsman Shop is complete in every detail and is exactly such an ee : It is driven by a Super-Power 4% H ; Electric Drill. The lathe, circular saw, and jig saw are all well constructed and real wood working tools. Each purchaser of a Craftsman Shop is given free of charge a 12- month course in Wood Craftsmanship, and 27 well designed blue prints of various pieces of furniture, toys and models. Full details and illustrations sent without obligation. A 10-day free trial is given. Can be purchased on Monthly Payment Plan— Write to-day! 12” BAND SAW Perfection in design and construc- tion, this won- der working band saw is positively the greatest value ever presented to the home 7 or shop me- §# chanic. Send § for details. 5% May be pur- chased on Time Pay- ment Plan... $39.00 Build this Airplane Yourself Ballanca True Scale, guaran- teed to fly, all ma- terials ........ $9.00 3-ft. model Send for your copy of our 56-page Get Yours! booklet which contains the scien- tific knowledge we gained through 20 years experience in modei airplane construction. It illustrates and describes famous air es, also all parts required by model builders, experimenters and inventors. 10¢ This booklet is mailed to you upon receipt of... . Your dealer can supply you. If not, write us. U.S. MODEL AIRCRAFT CORP. 397-399-C Bridge St. Brooklyn, N. Y. Be thelom Brown of Your Town You have heard of Tom Brown of the famous Tom Brown's Clown Band. You have prob- ably heard his records. You, also, might develop into a Saxophone Wizard and earn a princely in- come. Atleast, you can have alot of fun, be popular socially and in college, the side. It’s eas Buescher TrueTone Saxophone and easy to pay for it by our spe- cial plan. 6days’ trial on an ne, Cornet, Trombone, Trump- et or other instrument. Mention instrument for Free circulars. Buescher Band Instrument Co. 2771 Buescher Block (505) Elkhart, Indiana Base 28" long by 8" wide Table top 16" by 12" Outfit includes necessary attachments to rip, crosscut, bevel, grind, mitre, groove, sand, mortise, tenon and polish. Table tilts to 45° angle. Base for saw and motor makes it port- able. Makes 244” cut. \% H. P. double exten- sion shaft motor. Complete ready to plug into any light socket. Send for free folder of Saw Details, also Bench Lathes, Complete Work THE and other Hardware specialties. TH WILBAR CO., Inc. 2010 E. Arizona St. PHILA., PA. 13 Inches High 30 Days Free Trial 5 New Modeis ready for deliv direct a our factory. Astonishing new prices and tl rms. RIDER AGENTS WANTED to ride and exh sample. Save big Many models, on all MEAD Bicycles Do not buy until you get them. ont money. styles. Wi A definite program for getting ahead financially will be found on page four of this issue. at 8 Price, $325 Service , Fastest, Finest Outboard Motor ' for Runabouts, Cruisers. Racers Enjoy big-boat pleasures at a fraction of old- time costs. Snappy runabouts; roomy, sea- worthy cabin cruisers give surpassing speed and dependability when equipped with the great 4-cylinder Super Elto Quad. The last Hi-Speed word in outboard motor engineering. New Quad _ 1929 model far faster, 60% more powerful than last year’s model, official world cham- Quad pion. Send for complete catalog of Super Price, $295 Elto motors. Eito Outboard Motor Co., Ole Evinrude, Pres., Mason St., Dept. W, Milwaukee y 4Cylinder Super Ello @ This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. a Glimpses of Men in the Public Eye (Continued from page 129) ne In those days, the fee for a Sanitary analysis top price — was five ee and the analyzing a sample of sugar Seventy-five At the end of the first partners. vided $600! ae ig But they refused to quit. Their enthus: was justified, for a few years later the firm be. gan to prosper. Then Little’s partner se ina mp tee explosion. He canhédee the business with another associ . drew in 1909. — Since then, the firm has known Arthur D. Little, Inc. Today ais palatial three-story structure. Not the least interesting feature of the establishment js a series of part-size plants, including a pulp and paper mill and an oil refinery. Industrialists i; all parts of the world are among the clients of the laboratory. Little has served both as president of the American Chemical Society and of the Ameri- can Institute of Chemical Engineers. Re cently, he was elected president of the Society of Chemical Industry of Great Britain. He holds the honorary degree of Doctor of Chem- istry from the University of Pittsburgh. Father of the Skyscraper NEARLY half a century ago L. S. ton, a young Minneapolis architect, pat- ented the idea of the skyscraper, or “cloud- scraper,” as he then called it. The other day, in his eighty-first year, he received his first royalty on the skyscraper patent, and that despite the fact that the patent had run out!. It was a check for $2,250, one eighth of one percent of the cost of the new twenty-six Rand Tower in Minneapolis. It was signed by, Rufus Rand, a young capitalist who is some- thing of an inventor himself and who, in this manner, paid a belated tribute to the man who visioned our modern towering structures. Buffington’s invention was a braced skeleton of steel with a steel shelf at each floor to hold the masonry veneer. He conceived this idea in 1880, at the age of thirty-two. But it was not until 1887 that he found time to apply for his patent, which was issued the following year. In 1882 he drew the plans of his first “cloud- scraper —a twenty-eight-story building. His contemporaries called him an _ impractical dreamer. In the nineties the inventor formed a com- pany to protect his patent: But tall buildings were going up in many cities, and the company started numerous suits. These dragged on for many years, until, at last, the patent had run out. Buffington spent a small fortune trying to collect royalties. Roan in Cincinnati, Ohio, Buffington started his career as a draftsman with a railroad. His leanings, however, were toward architee- ture, and in 1869 he went to Minneapolis, then just emerging from its frontier settlement stages. Some of the largest buildings of the early days in Minneapolis were his conceptions, includi the old state capitol of Minnesota, several the buildings on the University of Minnesota campus, and the famous West Hotel, which still stands. In not a few of these structures did his sky- scraper ideas enter. In 1880, when he the Boston Block in Minneapolis, he used’ more cast iron and I-beams than was custom- ary at the time, though it was only a seven- story building. In the West Hotel he built the stories of I-beams, with girders across the second story. : Though he has never really reaped the fruits of his invention, Buffington has remained aa optimist. His advanced years and even severe eye trouble do not prevent him from s part of each day at his (Continued on page 131)

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RS soe SESE = a Sf 5 5° m e Ze§ 22 se6 bes Pepe E s eS ‘EF skilled ecabinet= makers use Maydole Hammers The careful work of cabinet making requires the skillful use of a good hammer. Skilled cabinet makers use Maydoles because they know from experience that there is no finer ham- mer made for their work. A hang that has never been equalled, press-forged tool steel heads with just enough crown on the face and sides to prevent marring the wood, and clear, second growth, air dried hickory han- dies put into the heads ‘“‘for good.” If you take pride in your tools and the work you do, you owe it to yourself to own a Maydole Hammer. Your tool dealer will be glad to show you the style and weight you pre- fer. Write for a free copy of Pocket Handbook 23*‘B.”’ Maydole Hammers The David Maydole Hammer Co. Norwich NY 2725 POPULAR SCIENCE MONTHLY Glimpses of Men in the Public Eye (Continued from page 130) drawing table. A small,wiry man with snow- white hair and beard, he sits in a room decorat- ed with photographs of more than forty large buildings he has designed. Through the win- dows he proudly watches the changing skyline of his city, with the steel and masonry build- ings of twenty-five, thirty, and more stories that he dreamed of and put on paper nearly fifty years ago, at last coming into being. He Makes the Camera Lie ONE afternoon a few weeks ago a man rang up Lejaren Hiller at his photographic studio in New York City and inquired: “Can you give me a photograph by noon tomorrow of a council of nations sitting in the shadow of the Pyramids with the Sphinx in the background?”’ “Sure!” Hiller replied. ‘“‘Do you want a lot of pomp and military regalia?” It was an easy task for Hiller—merely a matter of sitting down to his workbench and making the Pyramids and the Sphinx in minia- ture out of modeling clay, selecting models to represent national leaders and military figures, calling on his property room for the necessary costumes, and then focusing his camera. Two photographs were made. One showing the group of personages was superimposed on that of the clay models; the combination was re- we Haren: Fe and retouched, and by noon the next day the order was filled! Hiller, inventor of “creative photographic illustration,” does things still more amazing. His work is a continuous contradiction of the old saw that “the camera never lies.” He invented his process twenty-one years ago. A native of Milwaukee, Hiller made a comfortable living as a magazine illustrator. In his leisure, he experimented with photog- raphy. One day the idea occurred to him that, by combining painting and sketching with actual photography, he could get more realistic illustrations. In New York at the time, he was told by editors that the “‘stunt”’ was impracti- cable. One of the skeptics, a friend of Hiller’s, tossed him a story calling for an illustration of the villain standing beside a cactus, with the Rocky Mountains in the background, and de- manded to know how Hiller was going to photograph this scene in the city. Hiller took a picture of a building excava- tion. Then he found a villainous looking man to serve as model, dressed him in cowboy clothes, and photographed him. The picture of the excavation he turned upside down, giv- ing a perfect effect of a cave. Thereupon-he superimposed the photo of the bad man on that of the “Rockies.” The editor was de- lighted. Hiller’s success dates from that day. Soon business concerns caught the idea and began to order illustrations for advertising pur- poses. Since then, Hiller has been busy with camera, models, brushes, paints, and modeling clay, turning out “‘creative photographs” for calendars, posters, booklets, and other adver- tising material. The subjects of his “photos” range from Commodore Peary discovering the North Pole and the pioneers of *49 crossing the desert in covered wagons, to Santa Claus mak- ing a triumphal entry in his reindeer sled on the asphalt of Fifth Avenue. The World’s Strangest Zoo OME of the best four-footed friends a man ever had pass their lives in a great American institution of scientific research. How dumb animals are help- ing valiantly in the fight against dreaded human diseases will be told in a remarkable article in next month’s issue. OBSTRUCTION “SUPERRENCH” forthe first time... HEN you tackle your next repair job, have a Set of Obstruction “Superrenches’”’ handy. Then, when you’re up against an awkwardly placed nut no ordinary wrench will turn, try a ‘“‘Superrench’’. You’ll marvel at the way this useful tool, with its 75° angle opening, works in cramped quarters. And strong-- it will break the bolt, or strip the thread! Ask your dealer or write us. Automotive Set No. 2040 Five Obstruction “Superrenches’”’ ; ten different openings from 3/8 to 7/8” for popular nuts and cap screws. ‘ PRICE—$5.90, postpaid in leatherette roll. J. H. WILLIAMS & CO. “The Wrench People’”’ 246 Vulcan Street, Buffalo, N. Y. Every “SUPERRENCH” is Guaranteed for Life Against Breakage \WILLIAM ee 99 (Chrome-Molybdenum) © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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132 Village Smith Rings Anvil Chorus A chorus of content for this favorite pipe tobacco! We don’t know whether a spreading chest- nut-tree still stands in Branford, Connecti- eut. But we do know that Branford still boasts a village smith—by name, John Donnelly. A mighty man is John. In sixty years he says he’s smoked half a ton of pipe tobacco; and of all the brands he’s tried in his pipe he likes Edgeworth the best. Read Mr. Donnelly’s letter: 47 Cedar Street Branford, Conn. Larus & Brother Co. Richmond, Va. Gentlemen: Within the past sixty years as a pipe smoker I have used about a half ton of tobacco. Of all the pleasures I’ve enjoyed, tobacco costs the least. Of all the brands ay L have tried, your Edgeworth is the est. John Donnelly, the Village Blacksmith, Branford, Conn, As John swings his heavy sledge a chorus of sparks dances from his anvil—and a chorus of content puffs from his pipe! And why not? Nearly all pipe smokers are calm, serene fellows. Come to think of it—you don’t know many pipe-smokers of the nervous, flighty breed. Pipe-smoking runs to calm, thinking men. Ask a pipe-smoker a question; he takes a puff on his pipe and gives you a straight, sound answer. Somehow with a briar between your teeth you simply don’t have troublesome, disordered thoughts. Try this offer—F REE! There’s a lucky horseshoe on this page— especially if it’s a long time since you’ve smoked your pipe! It’s this free Edge- worth offer. Simply write your name and address to Larus & Bro. Company, 10 S. 21st Street, Richmond, Va., and you will get some welcome pipe- loads of Edgeworth Ready-Rubbed smok- ing tobacco all ready to load in your pipe. If you like these trial helpings you can be sure you'll keep on liking Edgeworth, for (as you will dis- cover) its lik- able quality never changes— tin in, tin out. Year after year, Edge- worth smokers say, they stick to the same mild, winning blend that always comes packed in the familiar blue tin. —the Edgeworth Station. Wave Length 270 meters. F; cy 1110 Kilocycles.—Special Fea- ture: The “Ederworth Club” Hour every W ednes- On your radio—tune in on WRV A,Richmond,V a. ] day evening at nine o’clock,Eastern Standard Time. POPULAR SCIENCE MONTHLY The Man Who Made Radio Talk (Continued from page 32) kept young De Forest going. He had a strong natural bent for mechanics; he was going to be a mechanical engineer. But electricity was looking up. The war between alternating and direct current had been fought and com- | promised. Electric railways were spreading all | over the country, Niagara was being harnessed for power, one could telephone a hundred miles, every big town had its arc lights in the streets. De Forest read everything he could get hold of about electricity, absorbed all that his professors at Sheffield could give him. He was looking ahead. What was to be elec- tricity’s next step? Where could a youth on the threshold of life find his best toe-hold in this field? J pw GET means to pursue his experiments and his education, he worked for a time, after graduating with the degree of B. Sc. in 1896, for the Western Electric Company in Chicago, the largest makers of telephone equipment. The Spanish war came along, Yale men organized the “Yale Battery,” Battery A of the First Field Artillery, Connecticut Na- tional Guard, which saw service in Cuba and in which De Forest served as a gunner. Then he went back to Yale for post-graduate study and the degree of Ph.D. Great things had happened in electricity. Hertz, in Germany, had discovered that elec- trical impulses travel through the “ether” without wires. Tesla had startled the world by lighting an electric lamp at a distance, wire- essly. There is a streak of mysticism in Lee De Forest, a fondness for the occult and the un- known. Here was something which appealed intensely to the introspective, mystical- minded youth to whom the world was still a fascinating storehouse of unexplored mysteries. Electricity without wires! The very thought made him tingle. : **I would get a job with Tesla, if there were any possible way to do it, I decided,”’ he told me. “But just then a book fell into my hands which described Marconi’s early work in wire- less telegraphy. “There was the new, unexplored field—the field of communications. That was where the Hertzian waves could be made useful, if any- where. I knew that I had found my niche in the scheme of things.’’ E STUDIED wireless until he felt that he understood it as well as anybody did at that time. Marconi came to America in the fall of 1899, set up his antenna on Sandy Hook, and reported the Shamrock-Columbia yacht race by wireless from a tug. De Forest saw the Marconi apparatus. Marconi’s method of detecting radio im- pulses was by means of a device called the “‘coherer.”’ This consisted of a small glass tube containing two closely fitting silver cylinders with the small space between their ends filled with a mixture of nickel and silver filings in the proportion of about 20 to 1. The air was ex- hausted from the tube to prevent oxidization. When a radio wave passed through the filings, they “‘cohered,”’ or stuck together, permitting current to flow from a battery circuit, which operated a bell buzzer. The clapper attached to it continuously tapped the coherer, thus breaking the filings apart when the radio waves stopped. De Forest decided at the very start of his work in wireless that he would find a bet- ter way of detecting the waves. Some of De Forest’s critics have contended that his audion tube, which was the result of his search for a better detector, was merely an adaptation of the Fleming valve. 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W2Qeeked oF sahiitt ee isi? cee abcet li May, 1929 [fhe Man Who Made Radio Talk (Continued from page 132) ‘ King George, discovered that by Laie ee event in a gas-filled bulb, provid- sg second electrode in the form of a plate to ‘iis the electrons given off by the filament could flow, he had a valve which would convert ting current into direct, as it would let the electrical waves flow through in only one tion. De Forest’s audion tube introduced a third electrode, the grid, between the fila- mentand the plate, and made the Fleming valve into an extremely sensitive wireless detector. But De Forest told me the other day he had heard of Fleming or his valve when he set forth on the road of research which led to the audion tube. It was an amusing accident which set him on the trail of the conduct of heated gases as a possible answer to his prob- Jem. SET up a little laboratory in Thames Street, New York, where he began to hunt for a substance, a device, or a method which would pick up wireless waves. There were bat- teries and a Ruhmkorff coil in a closet, con- nected with the worktable by wires and a but- ton to set off the discharge. The experimental detectors were tried out by means of a tele- phone receiver, to detect the “click”’ of the dis- charge, if it were detectable. The noise of the spark from the closet made detection a matter for keen ears. “There were no headphones then, so I had to hold the receiver to my ear with one hand, manipulate the detector with the other, and the button with my knee,’’ De Forest told me, smiling reminiscently. ~*T got hold of a report of the work of a Ger- man electrolytic experimenter who seemed to | have something which might work. I followed 4 up his work and produced what I called a ‘responder.’ It would work, uncertainly, for half an hour or so, and then go dead.” An accidental observation seemed to put the experimenter on the right track. The vay light in the room came from a gas jet equipped with a Welsbach mantle. One night De Forest noticed with surprise that whenever he pressed the button, causing an electrical dis- charge, the gaslight grew dim. He tested this effect again and again. It worked every time. Later with his roommate and coexperi- menter he repeated the experiment.- The dis- charge of the coil clearly seemed to affect the combustion of the gas in the burner. De Forest started at once to work out on paper a theory of waves. HE next day the young experimenters tried again, this time with the aousk door closed. Nothing happened! _ Shey opened the closet door and the gas- light waned again with every discharge. They closed the door, and nothing happened. It was made painfully evident that the effect I had been so wildly excited about was an acoustic effect which had nothing whatever to do with electric waves,’’ De Forest told me. My associate became disgusted and quit the experiments. But the theory of heated gases which I had worked out seemed so plausible and full of possibilities that I kept on along lines and finally got what I was after.” With the aid of a Bunsen burner he first got the effect which he had reasoned out, but to be of practical value the gas must be heated elec- trically. He tried experiments with an arc lamp, found that it could be used as a detector, it was frightfully noisy. Some way of utilizing the heat given off by a filament inside of an incandescent bulb had to be found. _ “Thad a lot of trouble getting the vacuum in the bulbs right,’’ he said, recalling those early days of disheart- (Continued on page 134) the properties of heated gas in detecting wire- POPULAR SCIENCE MONTHLY PUT THIS Wo SS°8 HOME FREE for!0 Days-No Deposit. A New and Improved Workshop Here is a workshop built to a standard of perfection—accurate in o most durable in construction—easy to operate. It is absolutely ration— ependable and will withstand severe constant service. Try it for ten days at our expense and you will be convinced of its superiority. Suitable for Carpenters, Home Workers, Pattern Makers, etc. . Furniture manufacturers use MAC, THE Popu- LAR MECHANIC Workshop, for making furniture models. Manual Art Schools use it for instruc- SE pA UD RILEY CROSSCUTS, DRILLS, SURFACES, POLISHES, GRINDS, CUTS SCROLLS. tion. Home workers use it for pleasure and profit. 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POPULAR SCIENCE MONTHLY

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The Man Who Made Radio Talk (Continued from page 133) ening experiment. “At last I enlisted the aid of a maker of miniature incandescent lamps and we made bulbs with filaments of platinum, of carbon, and of tantalum. Tungsten had not yet been thought of for this purpose. Those early tubes resembled Fleming’s in that they had both the filament and the plate, but I had a battery connected in series between the fila- ment and the plate, which Fleming never had.” At last he had found what he had been seek- ing, a radio detector which not only served as a detector, but as a relay and an amplifier, as well. The American De Forest Wireless Tele- graph Company, first to utilize alternating cur- rent generators and transmitters, was formed in 1902, the year in which Marconi got his first signals across the Atlantic. The pupil was ahead of his master! HEN came his work for the Government. He built the first five high-power wireless stations for the United States Navy. He kept plugging away at the improvement of his tube. What would happen if he added a third elec- trode? He tried it, first with a strip of tin foil around the outside of the bulb, then with a grid be- tween the filament and the plate. Here at last was the most delicate detector yet devised. A weak electric voltage applied to the grid of the tube acted as a “‘trigger’’ to release a much larger flow of electrical energy in the plate cir- cuit of the tube. The tube actually amplified electric currents by adding the power from a separate battery. And by properly arranging the circuit, De Forest found that the grid per- mitted him to feed smooth, direct current into the tube and obtain from it alternating current at any desired frequency. The “trigger” amplifying action was adopted by the great telephone systems and made possible the renewal of the energy in long telephone lines as many times as was necessary to overcome the losses in over 4,000 miles of wire. You could talk from Boston to San Fran- cisco. And the oscillating feature of the tube made it possible to pump a steady stream of radio waves into an antenna. Radio began to talk! By the time the United States entered the war, in 1917, our Government had something no other nation possessed, a wireless telephone system which could be used between an air- plane and the ground, from point to point over land and sea, from ship to shore and shore to ship. And the credit for that, as the United States Supreme Court has just declared, is all. Lez De Forest’s. [THE war over, radio took its next great step forward, a step which De Forest and his wireless telephone had made possible—broad- casting. And De Forest turned to other things. He had made the radio talk; why not make the movies talk? Dozens of inventors were trying to do that. Nobody had thought of what seemed obvious to De Forest. By means of his audion tubes it was easy enough to make a light flicker in response to a human voice. If he ran a strip of photographic film in front of such a flickering light, the record on the film would be a photograph of a voice—of sound. To translate the picture thus made back into sound again seemed simple to him. Just re- verse the process. Instead of a light, set up a photo-electric cell in front of the film. As the alternately dark and light bands recorded by the voice passed in front of the cell, they would cause oscillations in the current passing through the cell. Pick up that current, amplify it, run it into a loud speaker, and you would hear the picture talk. So De Forest reasoned and so he did. The De Forest Phonofilm, (Continued on page 135)

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Old Town Canoe Co,, 1995 Main Street, Old Town, Maine. ‘Old Town Canoes” ee "A definite program for getting ahead - financially will be found on page four of this issue. POPULAR SCIENCE MONTHLY The Man Who Made Radio Talk (Continued from page 134) parent of the talkies, was born, and to its pro- duction and perfection he has devoted all of his experimental effort for the last eight years, until now the talkies have come into their own and the big laboratory in East Forty-Eighth Street is rushed to produce apparatus for mak- ing and reproducing talking films fast enough to supply the demand. “What are you going to do next?”’ I asked. “‘T have no definite plans ahead,”’ he replied. “TI am interested in what we are doing here, and in what others are doing in the radio field. I have been watching the experiments with television with considerable interest.” “What is going to come of them?” I inquired. “| THINK within two or three years we shall _= see television on a small scale being broadcast and received quite generally,’ he said. “‘It will be a long time, if at all, before we have it on any large scale. There is only a comparatively narrow carrier wave-band available. The larger the area to be covered by the transmitted picture, the higher the fre- quencies required. That brings us down into extremely short waves, a meter or less, which are absorbed by buildings. “It would be much easier to show a life-size television scene in the open country than in the city, for that reason. But the people live in cities, and radio must be brought to them. So I am skeptical about anything beyond small- sized images now being successfully shown by television.” “What are the other tendencies in radio?” “IT think it is going to be more and more use- ful for its original purpose, that of communica-, tions,’ was the answer. “* The facsimile method of transmitting messages is slowly but surely coming into use. When the public wakes up to its advantages it may supersede all present telegraphic methods. “T believe, too, that we shall see a great ex- tension of the use of short waves, up to thirty meters or so, for communications. Everybody in the beginning went after longer and longer waves and more and more power at the trans- mitting end. Now we are working in the other direction. Marconi has got surprising results, and improvements are going on constantly. I think we shall soon see newspapers, for ex- ample, using short-wave point-to-point wire- less for transmitting not only news and pic- tures but facsimile advertisements and the like. % A CHAIN of newspapers might transmit whole pages of news in facsimile to all the offices in the chain, and I believe something like that is being considered by some of them. “‘Beyond that I would not care to venture any predictions.” Time has left its mark on Lee De Forest. He looks older than his fifty-five years. But his enthusiasm has not waned, and while he has overcome a good deal of his youthful diffidence he is still shy, gentle, modest, and unassuming. He has a modest man’s pride in the honors which have been bestowed upon him, the Elliott Cresson medal of the Franklin Insti- tute, the degree of Doctor of Seience from his alma mater, the gold medal of the Institute of Radio Engineers, and a dozen others. One of the things he has done with the wealth which has come to him from his inventions is to es- tablish at Yale the De Forest radio library, containing everything published in any lan- guage on the subject of radio, and the De For- est lecture course, given by the foremost men in the field, eight or ten of them a year. And I think that perhaps what Lee De For- est is most proud of is a little booklet issued by Yale University in which his own name is coupled with that of another famous Yale graduate, Dr. Samuel F. B. Morse, inventor of the electric telegraph. 135 IF YOU CAN USE AN OU can save $20.00 in no time by using SMOOTH-ON NO. 1 to do your own household repairing—and in addition you will have that proud “I-did-it- myself” feeling. 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The Real Fathers of Flight (Continued from page 50) copyist had been aloft more than half an hour. The same day Orville gave Lieut. F. P. Lahm— now brigadier general—a short passenger trip, and was warmly congratulated by Secretary of War Wright, General Miles, and other officials. While near-plane pilots abroad togged them- selves in fancy flying garb, the inventor sailed in his business suit, cap, and low shoes. With Lieut. T. Selfridge, assigned as pas- senger at his own request to the War Depart- ment, Orville on September 17 embarked upon the one disastrous flight of his career. He and his passenger were laughing as their craft rose late in the afternoon and began to-circle the field. Laughter froze on their lips within a few seconds. The pilot heard an ominous tap- tapping. He glanced back and found that con- trol of the vertical rudder was gone. A cracked propeller blade had snapped the rudder wire. The machine wabbled for a crash on the bank of its fourth circle, 150 feet up. Orville lived hours in part seconds. He tried to balance by warping alone. By lightning-quick action he leveled the craft for a down glide, but had only seventy-five feet left. Moreover, the front rud- der was now defective. "G™ me twenty feet more!’’ moaned his agonized brain. ““Oh!’’ cried Selfridge, grasping a strut at the last fatal dive of the plunging machine. The Army officer died within a few hours. Orville suffered broken ribs and a fractured left leg. Sleepless through four days and nights of torment, the inventor was soothed in the military hospital by the presence of his sister Katharine. His first words as he lay stricken on the ground had been: “Tell my sister I’m all right.” Four days after the accident Wilbur in France made a world’s duration record of one hour and thirty-one minutes, and as he stepped from the plane remarked: j “This will cheer Orville up a bit.” It did indeed! It calmed the torments and brought the first sleep in ninety-six hours. Wilbur's feat across the ocean was triumphant proof to the world that the disaster at Ft. Myer did not imply futility of the airplane nor impair the future of aerial navigation. Besides this tribute and testimonial, Wilbur, fulfilling the French contract, cheered his convalescing brother by cabling home several thousand dol- lars. The cash was badly needed, what with a mortgaged home, a father retired from the active ministry, all savings spent, and the hope of payment from Uncle Sam indefinitely post- poned. YW meer, preparing to fly at Le Mans that summer, was his own chief mechanic and cook. It was suggested that he put ball bear- ings on his propeller shafts. He replied dryly that since he could not make them himself and would not trust the job to anyone, he would try to get along without this feature. His bedroom was a fair sized packing case within his shed hangar and the furniture consisted of a cot, a wash stand, and a camp stool. He made his own breakfast on an oil stove. A piece of hose attached to a water pipe comprised the bathing facilities. Eminent visitors did not interest him but his “‘face lighted up and flushed with pleas- ure” when sincere and intelligent callers praised his work. The French were captivated by the magical feats of the air-riding Yankee and intrigued by his austere personality. He kept the Sabbath, avoided women, abstained from tobacco, wine, and even choice food. What a man! Poets extolled hjm as a medieval knight. The peas- ants, viewing Wilbur and his craft with awe, made pilgrimages to Le Mans as though it was a shrine. Hawkers on the streets of Paris sold innumerable picture (Continued on page 137)

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May, 1929 just as the Super Heterodyne the Master Receiving Circuit " so is yICTOREEN The Master Superheterodyne eee And—un u have heard and used a 1929 Vic- toreen. Eitarenct realize what a marvelous improvement it is over any other type of Super ean, in a very few hours, assemble this master receiver. Not only do you have the pleas- ure of building it, but also you have the satisfac- tion of knowing that better can neither be built nor t. heart of this master circuit is the Victoreen Ko or ar vastly improved for 1929, tuned and matched to a precision of }4 of one gent, In addition, the Victoreen Circuit Reell contains improvements far ahead of its Complete Kits Available Either A. C. or D.C. Write for free Blue Prints and Special Dis- counts. State whether you wish A. C. or D. C. Victoreen Power Amplifier and “B” Supply Best Results from Any Receiver BLUE PRINTS, with list of parts and complete assembly instructions, will be sent upon request. The George W. Walker Company isers of Victoreen Radio Products 2825 Chester Avenue Cleveland, Ohio Work Out Your Own Ideas— With the H&A Wood Lathe © for turning, lamps can- for. complete informa- tion. A. @ ~ HESTON & ANDERSON 805 Market St., Fairfield, Ia. FREE CATALOG Just off the press. hows 50 items of footwear, clothing, tents, etc., for the fisherman and mo- tor camper. L. L. BEAN 361 Main St. Freeport, Maine FORMS TO CAST LEAD SOLDIERS, INDIANS, TRAPPERS, Hunters, Wild and — a 214 Wonderful True to Life’’ in eo eases en Henry C. Schiercke, 1034-72nd St., Brooklyn, N. Y. AIRPLANE 12-inch scale model of Lindbergh's Spirit of St. Louis. Scientifically jesigned and very realistic. Rises f: F POPULAR SCIENCE MONTHLY The Real Fathers of Flight (Continued from page 136) post cards and statuettes of the American, including portrayals of him as a Billikin in flight. Today a monument to him stands at Le Mans. At Auvours field on December 31 Wilbur broke another record, making seventy-seven miles in two hours and twenty minutes, which brought him the $4,000 Michelin prize and trophy. Austere and taciturn as he was to the public, Wilbur wrote home with gay freedom, telling about his gold medals “about the size of a small can.” Orville, having spent seven weeks in the hos- pital, sailed with his sister for Europe in Janu- ary, 1909. Katharine had the exciting job of “social manager” to her brothers. Perhaps knowing by intuition that there would be a lot of kings ahead, she laid in a couple of the best evening gowns that Dayton could supply, and added a trifle to her wardrobe in Paris. AU, a winter resort in southern France, be- came the scene of the Wrights’ activities and the focus of all continental eyes. The town gave the pioneers a field, hangar, and free quarters in a hotel with a French chef thrown in. ‘Somehow the brothers did not take to the chef's delicate art and soon retired to rough it comfortably at the field, leaving Katharine at the hotel. Orville’s health improved so that he could help his brother while still unable to fly himself. His courage was unshaken by his tragic accident. Wilbur played the school teacher at Pau, giving an unprecendented course in pilotage of a new vehicle to persons designated by. the French Wright company. There were no text- books on the subject,- none of the modern elaborate devices now used in ground school to test the pupil's senses, scramble his insides, and give him safe practice. Professor and pupil ex- changed a few remarks, then rose in the air and took a chance. Yet no one was hurt in any of the three dozen teaching trips. The honor of being the world’s first flyers taught by the Wrights was shared by Count Charles de Lam- bert, Paul Tissandier, and Captain Girardville of the French army. The brothers considered de Lambert their best friend abroad and were delighted by the favors of his six-year-old daughter who termed Wilbur “My Mister Wright”’ and Orville “Best Orville.” THE King of Spain arrived in February. He sent word ahead requesting an exhibition flight on Sunday. Everybody knows that a royal request is a command. But the Ameri- cans, whose father was a minister, politely re- plied that they would be pleased to entertain His Majesty on any week day. The king changed his schedule to suit while the populace brought out their flags. Alfonso romped into the hotel dining room, followed by suite and bodyguard, on a Friday night. Katharine was flustered, and relieved that she escaped the royal eye, not being at- tired in either of her evening costumes. After shaking hands with the brothers at the field early next morning, the Spanish ruler called for their sister. Katharine had just been tutored by Lady Northcliffe, wife of the Eng- lish rfewspaper owner, on how to make a curtsy, but decided on the spot to be herself. So she left out the curtsy and gave a friendly hand to the monarch, who responded with beaming smiles and compliments and told again how the veto of his queen and cabinet de- prived him of an ardently desired trip in the air. He spoke fluent English. As Wilbur landed from a flight, the excited young king ran and jumped over obstacles to reach the machine. Sitting in it beside the in- ventor he volleyed scores of questions and showed that he understood a good deal of the problem involved (Continued on page 138) This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. CeCoTypeJ-71-A —A 5-volt 14 a tube for use via the ou s eo 10 Te. 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The Real Fathers of Flight (Continued from page 137) in aviation. Afterward the Wrights had lunch with the king at a hotel. Leaving town next morning, the Spanish ruler went out of his way to shake hands with Orville and Katharine, and to salute her with raised hat. The airplane was launched at this time by a derrick weight, which had to be hauled to the top by a rope before each flight. There was keen competition among the high and mighty of Europe, assembled at Pau, for the honor of pulling on the rope. Those who were not allowed to heave felt it a privilege just to put their hands on the rope. Among those who participated in the hauling ceremony were Arthur Balfour, who had been Prime Minister of England, Lord Northcliffe, and the Duke of Manchester. Half a dozen years before at Kitty Hawk, the inventors had paid a man $1.25 per day for exerting his muscle on the virgin flyer. SOME of the worshipful notables envied the job of the Wright mechanic at Pau who solemnly prepared the plane for each ascent by walking up to it from behind and giving the tail a brisk wiggle. It was agreed that the wiggle was an essential detail? but being a simple act should not have been monopolized by a selfish mechanic. ““Where’s the Comtesse de Lambert?” said Wilbur one evening as twilight began to fall from the crests of the near-by Pyrenees. “Mr. Wilbur wants me? He cannot want me but for one thing!”’ exclaimed the moist- eyed countess ecstatically, returning to the field. She had not told anyone of her dearest wish, now to be fulfilled The silent American smiled at his friend’s wife and deftly tucked her into the seat. As the plane came back to earth she was speech- less with delight. Wilbur next treated his sister to her first jaunt in the sky. Despite all her familiarity with the machine, going back to the days when it was just a dream subject debated by her | brothers in the home living room, she had the | thrilling emotions of a novice undergoing a marvelous adventure. A little dazed and be- | wildered when the roaring craft left the earth, she was fearless because Wilbur was beside her. T NEWS that the King of England was coming, a host of his loyal subjects be- sieged the Wrights with letters, wires, phone calls, and personal visits. There were hundreds of messages from baronets, noble lords, belted earls, and other personages of the first rank. Many of these had no desire to hazard their necks by a trip aloft. They merely regarded the airplane as a social elevator and wished to be accorded their proper places in the royal picture. King Edward VII arrived on March 17. The inventors and their sister were presented to him at the field. Katharine shook hands with His Majesty, who spoke pleasantly. He was a stout figure with a pointed white beard, pass- ing into age and weariness. The brothers ex- plained their vehicle to the king, who listened | with courtesy but did not seem to have much interest in mechanical details. Wilbur made a flight in the royal presence and on landing said to his sister: “‘Sterchens, don’t you want to climb in?” Katharine replied she couldn't because of her large hat, whereupon Orville, grinning, stepped forward with cap and veil as pre- arranged with his brother. Thus the delighted Katharine had her second and most gorgeous flight before His Britannic Majesty and over the heads of peasants strewn along the coun- tryside i in gay Mardi Gras costume. ““See, a woman flies also!” cried the peas- ants, waving hands and bright headdresses. But the occupants (Continued on page 139)

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A man who had mastered the air looked at his passenger, playmate of childhood and woman he loved best, and nodded mean- ingly toward the sparkling Pyrenees as though to agree that life had been perfected and the last goal attained. The Wrights were in Rome in Good Friday week ‘to make flights and deliver a plane to the Italian government. Their hotel boasted of “central heating,” despite which the rooms were a bit chilly, and Wilbur remarked: “Guess what we want is local heating.”’ After he was more conveniently housed in a cottage near the flying field, Wilbur messed frequently with Italian officers and reported to his folks that he had made a record by devour- ing “‘forty-seven miles of macaroni.” The elder brother had arrived in Rome some days before Orville and Katharine, and was to be presented immediately to the King of Italy by the American ambassador. “MN HREE bows will be suitable for the occa- sion,” advised Ambassador Griscom in a note. ‘1 didn’t know,’ commented Wilbur later, whether it meant to wear one under the chin and one under each ear, or whether it meant to make three of them to the king at the presenta- tion.” Assuming that obeisances rather than triple neckties were required, Wilbur started to per- form before Victor Emmanuel at the palace. The tall, lanky American tilted once. He was halfway on the second bend when the short little monarch pushed him cheerfully into a chair and, taking a seat himself, began to talk in plain English, asking questions and making simple but pointed comments. There were no frills on His Majesty. While he showed less enthusiasm than the effervescent Alfonso of Spain, he had more interest in the airplane than the King of England. “ Mr. McMahon’s story of Wilbur and Orville Wright will be concluded in next month’s issue, in one of the most absorbing chapters of all. First after the Wrights N OBSCURE Frenchman and an almost unheard-of Dane are given leading places in a list of the world’s thirty-six “first avia- tors,”’ pilots of powered planes, recently com- pleted by the Aeronautics Branch of the Department of Commerce. After Wilbur and Orville Wright, numbers one and two, respec- tively, on the list, come “T. Vuia, France”, third, and ‘‘ Ellehammer, Denmark,”’ fourth. Despite the credit generally given the Bra- zilian aviator Santos-Dumont as the first to follow the Wrights, actually the first was the Frenchman Vuia, according to Maj.. Ernest Jones, of the Aeronautics Branch. Records he has examined show that Vuia made a short flight of about forty feet at Sartrouville, France on March 18, 1906, in a miniature tractor monoplane propelled by a “carbonic acid gas engine.” made a number of short hops, which ended with a crash on July 5, 1907. At Holm, Denmark, on Sept. 12, 1906, J. C. H. Ellehammer made his first cautious flight of about 140 feet. His monoplane was powered by a motor of only nine horsepower, curiously resembling the radial motors of to- day. By February, 1908, he had succeeded in covering nearly a quarter of a mile. In June, 1908, he made a number of 300-foot flights and then dropped completely out of air history. 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Wheres the can PLASTIC WOOD? Reg. U.S. Pat. Of. Cracks around a built-in tub. Water slopping through. Seal up the cracks with Plastic Wood, or Plastic Wood White Waterproof Tile Cement (which dries to a hard flat white). Not only for bath- room cracks, but for gouged or broken furniture, loose handles, rotted wood, mouse holes and other household re- pairs or depreciation, Plastic Wood is invaluable. It is an inexpensive, practical, household repair product that often saves many dollars and anyone can use. It a like putty, hardens into wood, is waterproof and grease-proof, and takes paint, lacquer or varnish perfectly. PLASTIC WOOD (Reg. U. S. Pat. Off.] For boat owners Plastic Wood is of the ut- most value in the Spring Fitting-Out. It not only saves much time and expense, but gives a far stronger and better job for many of the im- portant repairs. In order that Plastic Wood may be used most efficiently in boat work we have prepared a special 24 page booklet “For Boat Repair and Construction” that will gladly be sent free on request. Plastic Wood Solvent When working, it sometimes is desirable to soften or thin Plastic Wood, and because of its adhesiveness it will stick to tools or fingers. To soften or remove it use Plastic Wood Solvent in 25 and 50 cent cans. Hardens into Wood ¥% |b. can 35 cts. At Hardware and Paint Stores ADDISON-LESLIE COMPANY 315 Bolivar Street Canton, Mass. POPULAR SCIENCE MONTHLY May, 1939 I Am Learning to Be a Flyer (Continued from page 28) Very crisply came Jordanoff’s voice: ‘‘We will have to land. This motor is bad. Release the controls entirely.” I did so. I looked down. On one side of us were thick woods. On the other was a thick tangle of roads and houses. Between was a long, rectangular field. The motor sputtered again. I knew that we were about to make a forced landing. How many times had I read that headline: FAULTY MOTOR FORCES FLYERS DOWN! But I was not nervous. I had confidence in Jordanoff. In war and peace, he had flown 3,000 hours. His head was moving rapidly from side to side. Suddenly the nose went down and the right wings pointed at the ground. The ground came rushing up to meet us. We straightened. Then the left wings went down and again the ground came rushing up to meet us. Again we straightened. E SEEMED to float along behind the idling motor. The ground was suddenly within reaching distance. We skimmed over it. There was a gentle bump—a perfect three- point landing! (A three-point landing is one in which both tires and tail skid touch the ground simultaneously.) We coasted to a stop. Jordanoff turned around, smiling. I asked: **Was that a side-slip landing?” He answered: “‘ Yes. It was necessary. Even if we had had enough room to glide in, the wind was wrong. Whenever possible, you always take off and land into the wind. Because of the shape of this field we had to land across the wind. If the wind had been strong enough, we might have washed out our landing gear. Did you notice this field when the motor began to sputter?” I had not. In fact, so far, while in the air, the ground had been a meaningless confusion. I had fixed my eyes on the radiator and watched the wings out of the corners, to see that I was flying with the horizon where it belonged and that the wings were level. Only when necessary had I torn my eyes from the nose and wings to look down at the landmark I was steering for. It generally takes a student a half dozen lessons, I learned, to become ** ground conscious.” ORDANOFF continued: “It isn’t pleasant to be forced down by a bad motor, but this will teach you an important lesson. Always have your eye on a possible landing field. When that motor began missing, we were above this field. We could have flown on and taken a chance of finding another field. But you must never do that. There might not be an- other field. “Sometimes a sputtering motor merely means a little water in the carburetor, which may run through in a few seconds. But it may mean more serious trouble. If your motor starts sputtering or missing and you are over a good place to land, start circling about it. If your motor dies, you can land. If it stops sput- tering and settles down. to work again, you can fly on. It pays to be careful. **Every good flyer,”’ Jordanoff went on, “‘is a careful flyer. This is the one business in which a man often does not live to correct his first bad mistake. That may sound fatalistic. All laymen have the feeling that the life of a flyer hangs by a thread. This is an exaggerated idea. A flyer simply must get it into his head that he is not to make any mistakes. Every experience a flyer has, every contingency he meets, makes it easier for him to be careful. Therefore, the longer he flies, the safer he is in the air. Don’t get it into your head that, after your first solo, you are a finished flyer.” I had heard that before. In fact, I had heard it at least a dozen (Continued on page 141) — In the Grand Central Zone Hotel Montelair Lexington Avenue 49th to 50th Sts. NEW YORK CITY Just Completed and Opened! 300 Rooms 800 Baths Each With Tub and Shower Radio in Every Room Room & Bath $3—$5 per day For 2 Persons $4 — $6 per day S. Gregory Taylor, President Oscar W. Richards, Manager Booklet of Advice on Crarr neET and SAXOPHONE PLAYING, by Alexandre Selmer and Andy Sannella, world-known authorities. More authentic information than in ten private lessons. Mention instrument in which you are interested, 59 Selmer Bldg., Elkhart, Ind. {n Canada: 516 Yonge St., Toronto The Midget “‘Five-in-One”’ Slide \\\ is a combination Mannheim KY ric, Log-Log, Binary, \\\ tract Slide Kule. It will ins’ subtract, multiply and di logue Free. (Patented 1-17-22) Co.. Stuart. 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Reference, any bank or trust company, chickens. at once for two free books tell- ing how to dc I Am Learning to Be a Flyer (Continued from page 140) times before, from a dozen different pilots and students. Jordanoff continued: ‘‘Charlie Collyer used to say: “Be yellow and last long.’ I was looking at a recent Department of Commerce analysis covering six months of airplane accidents. More than forty percent were due to errors by pilots. Every one of those accidents might have been prevented if the pilot had exercised greater care. Most students think it is a dis- grace if they don’t solo before their tenth hour of instruction. That attitude is foolish and dangerous.” A few days previously, I had heard Charles Gaver, the school manager, saying to a man who was making inquiries about courses: “I wish all flying schools would discontinue the ten-hour course. It appeals to people be- cause it is cheap. But it’s too short. It gives the average student one or two solos. He goes away thinking he can fly anything. He is a menace to himself and everybody else.” H's and Jordanoff’s comments were brought home forcibly to me a few days later when Martin Van Voorhis, one of the students, was killed—the first student fatality of the 2,000 who have gone through Curtiss. No expert saw the accident, but it is presumed that “Van” was flying at 2,000 or 3,000 feet, got into a tail spin, and could not get himself out of it. His death was a great shock to all of us who knew him. He had been soloing four hours. It would be unfair to say that Van died be- cause he soloed too soon. No one knows or ever will know. But pilots with whom I talked all drew from that accident the same moral: A student should not be too anxious to solo. “Be yellow and last long.’’ Some pilots go so far as to say that a student would profitably fly with his instructor twenty-five hours or even longer before he soloed. But many students cannot afford to do that. There is, on the other hand, a strong argument in favor of early soloing: It makes the student self- reliant, and gives him self-confidence. UN he makes his first solo, he is apt to depend too much on his instructor. The more conservative instructors recommend a reasonably early first solo—a very short one— followed by a period of instruction flying, then more solos and more instruction flying—as many hours as the student can afford. Everyone, however, agrees on one golden rule: The longer you fly, the safer you are. The morning that Jordanoff and I made a forced landing in the rectangular field seems long ago. But I have not forgotten that it took him a half hour to adjust the motor that somebody less careful had checked out as O.K. We took off and flew back to Curtiss Field. The lesson was over. And I had several more items to jot down under the notation, “Be finicky.” OAR of the motor, the blast of wind on your cheek—can’t you imagine yourself in the cockpit with Larry Brent, touch- ing the stick with yourfin- ger tips, learning to fly? Next month you'll ride with him again, and you'll thrill at his own vivid story of adventures in breaking into aviation. do not break, bend or twist. Made from special Tungsten—steel, hand forged and heat treated thru- out. All The square shank Sizes & ta runs clear thru the Sold 3S handle to the steel Sie ya cap. It is springy Hardware 8 4 and tough and Dealers, ; will withstand Plumbing F and Auto- unusual prying motive and hammer- Jobbers. ing. The octa- gon handle The standard toguines & of hand-forged tools for the Auto & Aviation Mechanic, Plumber, Steam- fitter, Machinist and other Artisans. Every PLOMB firm grip. This is the strongest screw driver A This hand-forged sample key-ring screw driver, of PLOMB sent for 12c in stamps quality FEGIG cococceviccosoncsess ddodmmneseebncctbevneetstaten Address,........+++ sonesqqneventenpeanennnseceiottipn COIR. ccccesaccoacsctnncciniiertbantnaopesnanacavtannnn te made.. hand-forged tool is fully guaranteed. See display Board at your Dealer’s. © PLOMB TOOL CO. 2209 Santa Fe Ave. Los Angeles or 1146 W. Lake St. Chicago Indicate tools interested in for: Auto, Aviation, Plumbing or General Use. © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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Rates 40 Cents a Word. A 10% discount is allowed on all contracts for six consecutive inser- tions. Advertisements intended for the July, 1929, issue should be received by May 5th. Submit details of proposition with order. Books and Periodicals 4TH EDITION Revised pee down to date. “Radio Theory and Operating y Texanna Loomis. The standard radio text and reference book of America. 992 ages, over 800 illustrations, flexible binding. Price, .50, postage paid. For sale by hundreds of book- dealers throughout America and many foreign countries. Or may be purchased direct from the publishers. Send check or money order to Loomis Publishing Company, Dept. 22, Washington, D. C. THE Electrician's Wiring Manual, By F. Ek. Seng- stock, E. E. Contains all the information needed for the preees installation of lighting and power systems in ouses and other buildings. It completely covers inside electrical wiring and construction in accordance with the “7 Electric Code. Pocket‘size—flexible bind- ing. 448 p Price $2.50. + eel Science Monthly, 250 Fourth Cave., New York Cit

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May, 1929 MONEY MAKING OPPORTUNITIES SECTION a Comfort Behind Brick Walls (Continued from page 75) : of the shingles or siding a four-inch brick wall is built. The bricks are held to the wall driving spikes into the sheathing about every four courses of bricks and letting the nailheads be completely embedded in the mor- tar joints. To all appearances the construction is that of a solid brick wall. This brick veneer construction has the good qualities of a wooden house but with a perma- nent outside covering. ; Another form of veneer is to apply the four- inch brick to a wall of hollow tile. The tiles furnish the air space and also have a “scored” surface to which plaster may be applied di- rectly on the inside. The brick is easily bonded in with the tile to form an exceptionally fine wall. The sketch shows the simplest method of bonding, where a metal bonding clip is em- bedded in the mortar joints. The tile also comes in special shapes to allow interlocking with the brickwork for a more complete bond- ing. However, the cost of this brick veneer on hollow tile is considerably more than that of the other walls described. oon costs depend largely on where the building operation is taking place, the yariations in expense for different methods of brick construction can be expressed in a general way. The “ideal” method usually would be the cheapest form of brick wall. The four-inch brick veneer on four-inch wood studs would probably run about ten percent higher in cost, while the eight-inch solid wall, furred with one- by-two-inch strips, in most sections of the country, would be about twelve percent higher. The four-inch brick veneer on hollow tile would run as high as thirty percent more. That is, where a certain length and height of wall built in the “ideal’? method would cost $1,000, the same area of wall in four-inch veneer on studs would be $1,100, the solid eight-inch wall with furring would be about $1,120, and the veneer on hollow tile would be about $1,300. These figures are based on the assumption that the same quality of brick is in each case. It will be seen that Mr. Bentley has used various methods of construction which have effected economies. In no case, however, has he made a substitution which is less sound or where the upkeep would, in time, more than offset the initial saving. In considering the specifications for your house, bear these facts in mind, remembering that the cheapest does not always mean a saving in the long run. What Do You Want to | Know About Building? | ORE articles on building, in which experts will escribe modern, economical methods of construction, will appear in coming issues of POPULAR SCIENCE MONTHLY. Besides the information in these articles, readers can ob- tain free advice on questions relating to building materials and equipment from the Pop- ular Science Institute Building rvice. Supplementing this service, booklets are being prepared. The first, a twenty-four-page treatise on ‘Insulation in Building Construction,” is now available at twenty-five cents a copy. Address Popular cience Institute Building ice, 250 Fourth Avenue, New York, N. Y. HILE you are dreaming of making money ... enjoying life... why not train your talent for drawing? A fortune may be at your finger tips if you train them now. Many people do not realize they have artistic ability. Through art, you may find the way to a famous name and a large income. Artists are paid more today than ever before. Since the war, rates for art work have increased tremendously. Advertisers and publishers are paying millions of dollars annually to those who are trained in Modern Art. 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Free Book a World-Famous Flier shows how Y# can get into AVIATION Hiss is the book that tells a Aviation offers i ny Cer errirg Walter Hinton—hero of history-making flights— gives you the brass tacks of Aviation Today. He shows you exactly where your opportunities lie— exactly how to fit your- self for them. Here is a book for men with too much backbone to stay chained to a small-pay job—too much adven- ture in their blood fora humdrum_ grind — too Trail-blazer, pioneer, explorer, author, in- structor. AVIATOR. first man to pilot a plane across the Atlantic—the famous NC-4—and first to fly from North to South America. First, too, to explore the jungle fagstnesses of the upper Amazon. The man who was a crack flying instructor for the Navy during the War; who today is training far-sighted men for Aviation. ; Hinton is ready to Much good sound busi- back YOU up to the ness sense to let this op- limit. His ook is yours FREE for the Portunity of r lifetime coupon below. outgrow them! THE RICHEST, FASTEST GROWING INDUSTRY THE WORLD HAS EVER KNOWN Cities everywhere are building more airports; 24-hour shifts are racing construction on new plane and equip- ment plants. Air lines, air service of every kind is doubling and re-doubling itself almost while gra watch! There's no doubt about there being BIG PAY plus a real future for YOU in Aviation. Your one sure move is to get the right training—QUICK! AVIATION IS READY—HINTON IS READY NOW IT’S UP TO YOU : Hinton will train you for Aviation, right at home in spare-time. His proved course teaches all about plane construction, rigging, repairs, motors, instruments, theory of flight, navigation, commercial Aviation. Whether you plan to fly, or want one of the forty Big Pay ground jobs, you must have this ground work first. Hinton’s Free ol tells you how to start. Clip the coupon and send it TODAY! AVIATION INSTITUTE OF U.S.A. WALTER HINTON, President 1115 Connecticut Avenue Washington, D. C. Mal Now for Pack Lieut. Walter Hinton, aT Aviation Institute of U.S. A., 1115 Connecticut Ave., Washington, D. C. Send me your FREE book, “Wings of Opportu- nity,” telling how you can give me my “ground work” right at home. DE GheRewoseccdaccececass Bncccckdtesicee Te se nesepepanenepanenennal MONEY MAKING OPPORTUNITIES SECTION May, 1929 Putting Lightning to Week: (Continued from page 19) Does lightning prefer some trees to others— oaks to beech trees, for example? Superstition says it does, and science agrees. Oaks are starchy trees, good conductors of electricity and therefore prize targets for lightning bolts. Beeches are oily and are far less frequently hit. Pine and fir trees are highly susceptible to light- ning. Safer shelters are maples, chestnut, alder or ash. Is it dangerous to be out in a thunderstorm? Statistics show that you are as likely to die from a mad dog’s bite or from being hit by a falling brick as by lightning. But, of course, people are killed by lightning—some five hun- dred a year in this country—and it is well to be careful. If you are caught in a thunderstorm a tree is poor shelter, as it may draw lightning; a cave or the foot of a cliff is a good one. Ina home, safety is practically certain. Even if lightning tears off or sets fire to the roof, it seldom can penetrate within. It will run off harmlessly into the earth through the metal pipes of the plumbing system or the wires of the electric supply. Because of its steel construction, a modern office building is lightning-proof, in spite of the height that would otherwise make it a good target. It even shields the area around it. The Woolworth Building, for example, attracts bolts to it and protects surrounding buildings with a “‘cone of safety” in which no bolt will strike. The Pulitzer Building, just a few feet outside this “‘cone,”’ has been struck. ONE man claims that lightning rods “draw lightning;”’ another that they prevent it by discharging the electricity that is accumulating in the air. Which is right? The answer is that both are correct. Some flashes probably are prevented by the’ rods, while others actually do hit them—as many cases show—and are carried safely to earth. The réle of the rod and wire is apparently less of a conductor than a guide. One type of lightning bolt, however, does not seem to follow any of the known laws of elec- tricity, and strikes where it will—lightning rod or no lightning rod. Dr. N. E. Dorsey, of the National Research Council, suggests it may be a “‘dart”’ of electrons which, unlike those of an electric spark, actually possess momentum and add to their number as they crash earthward— no less, in fact, than the legendary “‘thunder- bolt” of ancient times. Fortunately such bolts are rare, if they exist at all; they remain shrouded in mystery. [Hat lightning may start simultaneously from the earth and the clouds, and join in the middle, is the startling fact disclosed by Prof. C. V. Boys, British physicist, who suc- ceeded in photographing a flash at Tuxedo, N. Y., with a camera of his own invention. He had carried it around the world with him for twenty-six years waiting for a chance to get just that picture. Other photographs have re- vealed that the apparent zigzag path of light- ning is really a corkscrew, or spiral. So rare that only about a hundred cases of it have been reported in the last century, is “ball lightning.”’ Until recently many experts denied its existence. Mysterious, luminous balls of fire occasionally appear in the air during a thunderstorm, say witnesses. They float lei- surely into windows, or down chimneys, and attach themselves to metal objects, according to the stories told. Often they explode with a loud report, leaving what is often described as a “sulphurous” odor. A few accounts tell of these balls alighting upon human beings and burning them. Such stories usually have been dis- counted by scientific men. Recently, however, the first photograph purporting to show ball lightning, made by an unnamed Swiss photog- rapher, was submitted to the French Academy of Sciences by M. E. Mathias. It showed a aan forked lightning flash that divided into fj parts, each of which terminated in what pote to be a luminous ball. Meanwhile a British chemist, E. Kilburn. Scott, suggests a startling but simple theory of ball lightning. He proposes that the electric power of a lightning flash, under favorable cir cumstances, may fuse the air’s constituents into a liquid ball of nitric oxide gas, a Colorless poisonous gas, produced by the sudden chan, of pressure and charged with electricity. t “We know,” he points out, “that when lightning strikes through the air it ‘fixes’ or forms into nitric oxide more than 100 tons of nitrogen each year. In the sudden expansion of air that follows a lightning bolt, conditions are extremely favorable to the production of g large amount of the gas chilled in a concep. trated and probably liquid form. “TF THE gas were ‘rolled up into a ball’ by the lightning flash it would gravitate slow- ly to earth, in exactly the way observers have described. Meeting some animal or vegetable material, which it can ‘nitrate’-—such as a haystack or a tree—we know that such a ball of gas will explode. A violent chemical reaction, similar to that of an explosive, occurs.” Less mysterious than ball lightning, but fully as weird, is an electrical display known as “St. Elmo’s fire.” An unusually spectacular example occurred recently in Colorado. Ghost- ly flares played about the summit of Pike's Peak at night. So brilliant were they that they were believed to be signals of a party of strand- ed mountain climbers. Three aviators iW about the summit looking for human beings, but could find none. Evidently this was a display of St. Elmo's fire, familiar to sailors in the curious crackling flames that play about mast-tops on a erisp, snowy night. At the former observatory at Ben Nevis, Scotland, such displays were ob- served as caps of light on lightning rods. Oc casionally jets of flame hissed upward from objects atop a tower, reaching a height of six inches at times. An observer, Angus Rankin, reported his hair, hat, and pencil aglow with the strange electric fire, but he experienced no inconvenience save a slight tingling sensation in his hands and head. Even familiar forked lightning plays strange pranks. It recently wrote its signature upona Middletown, N. Y., man, who was struck bya bolt. His skin bore a pattern of bright pink lines, the burns of the electric current that had flashed through his body. After a day or two they faded out and disappeared. Observers strolling along the sand of beaches occasionally come upon rootlike tubes of glassy substance, often projecting an inch or two above the surface. Dug up, they usually are several feet long, with branches and _ twists. They are the result of a direct stroke of light- ning. Tremendous electric currents generate the enormous heat required to fuse wet sand into solid glass, in the form of long hollow tubes. Remarkable specimens of these “ful- gurites’’ are now in museums. Wits such testimonials to the power of lightning, it seems incredible that any man struek by it should escape death. But elec tricity at tremendous voltage obeys no a laws. A New York farmer, for instance, t refuge under a tree in a thunderstorm. = found him later, unconscious but alive, stati naked. A bolt of lightning had scattered his clothing in bits about the field. A New Eng land man was knocked down by a stray fl and the soles of his shoes torn off. The best explanation is that if the skin of a lightning victim is moist with perspiration, the instante neous steam generated by the heat of a flash acts like a miniature explosion and tears clothes or shoes. oe wa @aeaaea & ww. Saw ee ePaee sc sc row eae om LSU Uae oO elle ee eo Sere > imseace & wn ss TH £2EeE —_ = oe ® 38 Vers aecreooQn 2 ee | @¢eec

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AY, 1929 nto five - Seemed Kilburn. heory of electric able cir. stituents colorless 1 Change city. at when fixes’ or ) tons of nsion of Lions are on of a concen- ball’ by ite slow- ers have egetable ch as a a ball of reaction, ing, but TOWN as -ctacular ». Ghost- f Pike's hat they f strand- Ors LW | beings, . Elmo’s rackling a erisp, atory at were ob- rds. Oc- rd from ht of six Rankin, ow with enced no ensation 3 strange e upon a uck by a zht pink that had y or two “beaches of glassy or two ally are | twists. of light- generate yet sand - hollow se “ful- ower of uny man ut elec- ordi oa .. They e, Si ered his ow Eng- ay flash “he best ightning nstanta- a flash ears ne Mar, 1929 ———— Do Birds Fly by Radio Compass? (Continued from page 31) n, the winged travelers start prepara- tions for their voyage. There are hectic doings in the woods and in the fields. Every minute of daylight is used by the intercontinental commuters to accumulate the fat that will give them the energy and endurance to fly enormous distances without “refueling.” Then comes the “signal”?! The frost line moves down from the North Pole and simul- taneously great groups of migratory birds head southward. The first to leave are the arctic tern and the golden plover, which for- sake their darkening subpolar home—the plover for a glowing South American winter resort; the tern to find, after some 11,000 miles of weary winging, a haunt in the Ant- arctic as cold and bleak as the one it left in the Far North! HIS Arctic tern, by the way, because it is the champion long-distance nonstop pilot, is the subject of unceasing observation by ornithologists. Mr. Nichols told me of a re- markable instance proving its flying powers. 0. L. Austin, Jr., of the Museum of Com- parative Zoology at Harvard University, caught a nestling Arctic tern in Turnevik Bay, Labrador, and placed an identifying band upon its leg on July 22, 1927. It was picked up in La Rochelle, France, on October 1, having flown 2,500 miles at the tender age of three months! Even more amazing is the feat of another nestling tern banded in the same bay the following year. It was found fifteen miles southwest of Port Shepstone, Natal, South Africa. It had flown 9,415 miles from its nest before it was four“months old! By the time the frost line reaches Canada, the wild geese, ducks, loons, and cranes take to the air, blackening the skies with their huge mass formations. Now the “white line” enters the United States, and our friends the robins, bobolinks, and warblers are on the wing, flying by night and hunting food by day. Southward rolls the frost line and finds the martins, chimney swifts, and barn swallows ready for the voyage. Hawks and gulls are the last to depart. On their long journeys, most birds seldom fly higher than 3,000 feet, but strong flyers have been known to reach an altitude of 29,000 feet. The speed of the smaller perching birds is usually from twenty to thirty-seven miles an hour, that of ducks and geese from forty- two to fifty-nine. Individual cases of speeds far in excess of these figures have been recorded, however. Recently an airplane pilot raced a migrating swallow and found it was making seventy miles an hour! PEAKING of swallows, Mr. Nichols sug- gested that, if it had not been for those little birds, Columbus might never have dis- covered America! “Did you know,” he asked me, “that Columbus made two entries in his log—one on October 3 and the other on October 7, 1492— showing that he calmed his mutinous sailors by pointing to large southbound swarms of birds as proof that land must be near? Land was sighted on October 12. The birds did not come sufficiently close to the Santa Maria to be recognized by Columbus, but the time of their appearance in the neighborhood of San Salvador, now Watling Island, makes it fairly certain that they must have been barn swallows.” “What of the migratory urge itself?” I asked Mr. Nichols. ‘How is that explained?” _ “The explanation most commonly accepted is that the shifting food supply is the basis of birds’ seasonal movements. Another ascribes the migration impulse to in temperature, the birds passing south to escape the (Continued on page 150) ee MONEY MAKING OPPORTUNITIES SECTION TTT ee ELECTRICITY. ip Tus NEW, easier way shows you just how : electricity acts and how tocontrol it. Trains you quickly for a big pay job, $60 to $150 and more per week, in this rapidly growing field. , Right in your own home, in actual mov- ing pictures, you see electrical machinery of all kinds, in operation. You see moving diagrams which make every point clearer. $75 Projector Given Every student gets a $75 DeVry Motion Picture Projector to keep, at no extra Eg | Movies Teach You at Home cost. So simple anyone can operate it. Thou- sands of feet of fi DRAFTING OUTFIT of professional qual- ity also given, without extra cost. m furnished. COMPLETE We Help You Get the Job We pledge in writing, on your enrollment, to a give you the training and employment serv- r) ice necessary to get a better job and a raise o ES in pay, or you need not pay a cent. If you e O want more money, send coupon now ont % for details of this great opportunity. ? Se > 5%, The NATIONAL SCHOOL of Pid HSS . VISUAL@EDUCATION ,22r3% | . “Che Film Way to Bigger Pay Po “ a fe) book, “The Film W. OS a) ge FREE to Bigger Pay,*tells how: we 6 Ox Ce PP "a use movies to train you in spare time at fis home for a better job. Get your copy OM. 33 now. Mail the coupon today. 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You travel--or remain near home, For ten years this schi trained men and placed them in Railway Traffic In- requires 3 months spare time home instruction, and you’re quali- fied to step into a salaried position that, with experience, will $175, $200, 50 per month. We'll train you for Traffic Inspection, and upon completion. cssist ou to a position pa at 1 $120 per month, plus expenses, or refund your tuition, Write for Free Booklet Now! It tells all about Traffic Inspection--how it has started hun- dreds of to bi bs--whatit can do for you--how we can assist you to 8 anal, im with rapid advancement. Standard Busi Traini g Institute Div. 3, Buffalo, N.Y. ELECTRICAL ENGINEERING school fn Ameries, 24 B.S. Degree Spec eh me which you may the fee. ¢ FREE CATALOG irainiag and the Mention ame, education, and the course about details of our Dept, P. S. M. 529 Milwaukee, Wis. ADDING MACHINE VEST POCKET SIZE DDS, SUBTRACTS, TIPLIES, DIVIDES —— eg of , machine. 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Axy MAN who can read and write and use a pair of pliers can become an electrical expert and free himself forever from the long hours and drudgery of a small pay job. And you can learn the BIG PAY profes- sion of electricity right in New York City— the heart of the electrical world—the city of 100,000 jobs. At the same time you are learning the BIG PAY profession you can be enjoying the sights and wonders of New York, the modern Bagdad Be an Electrical Expert Graduates of the NEW YORK ELEC- TRICAL SCHOOL are in demand by all the big electrical companies. Or, if you prefer the independence of a business of your own, there are thousands of oppor- tunities for efficient, dependable men to become electrical contractors. When you are your own boss the money you can make is limited only by your own energy and ability. Personal Instruction The NEW YORK ELECTRICAL SCHOOL is not a correspondence school. You learn by doing—by personal instruc- tion on full size standard electrical equip- raent under the personal supervision of trained instructors. At N. Y. 8. you train your hands and mind at the mm © mY You learn the theories of electricity you are shown how to put the theories into oma practice by solving the problems with your own hands. The man who has learned electricity by_ actually doing electrical work under intelligent personal instruc- ye can go to any part of the Ry and be sure of ag . There are N. Y. E. 8S. Graduates in all the countries of the world. Write today for the iS are ee booklet giving full in- formation about the N. Course and sho ovtns pictures of the equipment available for your person use in our two seven-story buildings. The NEW YORK ELECTRICAL SCHOOL 40 W. 17th Street, New York puseeesecccens MAIL TODAY emeruareaees THE NEW YORK ELECTRICAL SCHOOL 40 W. 17th Street, New York. Please send me FREE your 48-page booklet. It is understood that this request puts me under no obligation. CORREO EH EEE Do Birds Fly by Radio Compass? (Continued from page 149) cold of winter as soon as the cooler air of autumn gives them warning, and, of course, returning again when milder weather sets in up North.” The flights of Canadian geese seem to offer proof of this theory. It has been observed that their yearly arrival at each stop-over point on their journey is timed by the tem- perature at that point. “Then we have the theory that birds naturally turn to the region of greatest light and leave that where light is curtailed, follow- ing the sun. Still other theories explain the migration urge as the outcome of the power of flight in which the bird rejoices, and as the result of certain glandular activity. “But all of them,’’ Mr. Nichols continued, “leave many curious phases of bird life un- explained. For instance, why does the Arctic tern, whether it originated in the north or south, make a weary 22,000-mile round trip to spend its life in the perpetual daylight of the subpolar regions? And why does the yel- low wagtail of Alaska fly to the Orient and spend the winter months along the coast of China? Why do six different species of birds breed north of the Arctic Circle and winter in Patagonia at the southern tip of South America?” . ANP your own theory?” I asked Mr. Nichols. “I believe,” he replied, “that the struggle for existence has much to do with migratory bird habits. Migration begins only when a species has increased to a point where it is crowding its range. indiscriminately. Some succeeded in return- ing occasionally to the original home, perhaps from only a short distance. With this homing habit once established, the distance between winter and summer homes may have become greater and greater. “A recent example illustrates what I mean. Since the irrigated lands in the West have become settled, the bobolinks have extended their range a thousand miles beyond the Mississippi Valley regions that once marked the westward limits of their range. Yet, each fall, instead of heading directly south, these birds fly a thousand miles eastward to start on their migration from the old spot. “This theory does not, of course, explain the principles that have controlled the migra- tion habit. The truth is that the entire matter of migration is so complex that no one single factor can be given as the absolute cause.”’ R. NICHOLS told me some of the bizarre superstitions concerning bird migration in olden days. ; “Do you know,” he said, “that in early times the disappearance of certain birds was attributed to hibernation? They were sup- posed to pass suddenly into a torpid state and so spend the winter hidden in caves and hollow trees or embedded in the mud at the bottom of marshes, ponds, and streams! To this day, peasants in southern Europe still think that the smaller birds congregate on the shores of the Mediterranean Sea, where they wait for a suitable opportunity to ‘book passage’ on the commodious wings of storks and cranes! “In a treatise published in London in 1703, the author expressed his belief that migratory birds, on leaving England, flew straight to the mocn, where they spent the winter season. He had even timed the lunar trip; it took exactly sixty days! “Even the great Swedish naturalist Lin- naeus, the founder of modern botany, actually thought that swallows plunged headlong be- neath the waters of a neighboring pond to - -the winter hibernating in the mud at e bottom!”’ (Continued on page 151) At first birds wandered | Become a musician so qui to astound everyone. Learn by a ing real music—instead of tie “exercises.’’ You'll soon become the most popular person in your “get.” New Easy Method Nothinz else like it for thor, and rapidity. So simple that young and old find it easy, to play with skill. No “trick music”—but ge tual notes, learned quickly Tight PICK YOUR in your own home. INSTRUMENT FREE BOOK and Demonstration —— eu offer this wonderful musical Ukulele Flute portunity. Send for thea t before copies are exhausted. Y, be astounded by this easy, rapid way to become a veritable’ master of your favorite instrument, Ip. struments supplied when cash or credit. — em ne U. S. SCHOOL OF WV MUSIC, 85 Brunswick Bld Send me your free fon Le Lessons in Your Own Home” with introduction by Dr. orn arp Trombone Cello Mandolin Piccolo Si it singi g nging Piano Accordion Voice and Speech Culture Drums — Traps Automatic vinmer Control Banjo (Piectrum, 5-String Crane. Also Free Demonst or Tenor) Lesson. This does not ye under any obligation. | MPTP eT TT TT TT BBBGOEB «00:6. .:0:0:0:0:0080000000050600s000000 0 Have you PIDs 56:56. d ada eerbmee this Inst ?. ......5.44, R 4 Fields of real opportu: nity. Big pay—a permanent position or a business of your own. 7 Hil® dollars spent last year in one of these Ary. alone. Train here in Chicago, America’s in dustrial center. 2-yr. a and 3-yr. B.S. Degree Paci Courses. Special 4 months’ practical course in Drafting. Other short courses. Earn while you learn. Enter any time, Day and evening classes. No time wasted. co Empenee Bureau. Lowtuition—easy terms. Athletics. Success ply ates everywhere. Free 80-page ‘‘Blue Book.’’ Address the President, Dept. E-82, 118 E. 26th St., Chicago, i. ane CE Royal. ete. All late models, completely refinished brand new. GUARANTEED for ten years. Sendno eee free ca shows actual — in fullcolors. our direct-to-you easy payment plan and 10 days’ trialoffet, international Typewriter Ex,, 186 W, Lake St., Dept, 538, Chicago, Ml. y step. You can train at home dar JAY “Re in legree of LL.B. conferred. ad every See neers, We ant a ind mate aie aoe Ae a Guide’* an **Evidence’* ” Sooke FREE y . 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ume 2 =} ir Sees obs Hee PPS NS ° = m i ee Fg lbs ge 4 ma (—>Y| - Ue Ral May, 1929 MONEY MAKING OPPORTUNITIES Pe pirds Fly by Radio Compass? (Continued from page 150) the United States spend the winter. Great flocks of them fly south, their number increas- ing as they go. They reach the Gulf of Mexico and disappear! A plausible theory is that they ‘ate to South America, as do other birds, because of their dusky hue and swift, darting flight, are not noticed among the swarming armies of brighter colored birds. A great aid in learning the habits of migra- tory birds has been that of banding them. This consists of trapping a migratory bird, clamp- releasing it again. The United States Bio- ical Survey keeps records of banded birds and reports of their movements. Since 1920, the Survey has established some 2,500 banding stations, operated by volunteer students of bird lore under permits of the Department of Agriculture. So far, more than 450,000 birds of 231 different species have been banded. a trapping methods used at present, Mr. Nichols told me, were developed by §, Prentiss Baldwin, of Cleveland, Ohio, who is president of the Inland Bird-Banding Association. The wire cage trap he invented does not injure the bird and is most valuable because it permits the making of consecutive records of the same specimen. Mr. Baldwin started bird-banding a few years ago as a hobby; today he is a recognized authority on ornithology and his two big sta- tective agencies. Among other strange facts Mr. Baldwin has established that birds have a family life in many respects similar to that of men. He found that the same pair of birds usually live together for a number of years. The older birds, as a rule, are satisfied with the first place in which they set up house- keeping. But often the ambitious youngsters decide that the neighborhood is no longer good enough for them and, shortly after they have learned to fly, move to another section. Occasionally, Mr. Baldwin has observed, birds divorce each other and find new mates. ‘But despite the great volume of knowledge bird migration remain unsolved. Some’ day, no doubt, science will penetrate the veil that now shrouds the magic of these long aerial treks. Then we shall really know whether birds of passage are guided by miniature cerebral “radio-compasses’’ or whether they are, per- haps, the little masters of some strange astronomical art that enables them to set their course according to the sun by day and to read the stars by night. “Average Inventor’? Begins His Work at 25 PROFESSOR at the University of Michi- gan has discovered the “average inven- tor,”.and tells us how long he works on an idea, at what age he applies for his first patent and how much money he makes. By sending out questionnaires to 137 typical inventors, picked at random from Patent Office records, and taking the average of their replies, he arrived at his conclusions. _ This “average inventor,” the professor says, is bitten by the “bug” at the age of 25. He is $1 before he applies for his first patent. He on inventing things for sixteen years. eapends on the average, one year, eight s and three days on each invention. In teturn for his work, he averages $37.25 a week. But the thrill of creation and the solving of Pieblems that have baffled others, give the Mventor the real reward for his labors. ee tions near Cleveland are veritable bird de- gained in recent years, most of the puzzles of | [tis still a mystery where the chimney swifts | ing a band, which is serially numbered for | identification, upon its left leg, and then | HERE is a truly revolutiona can openers is ended land can — cans automatically the new, simple, safe, vy easy way "Weems universally detest the old-style can opener. tically in every home cans are being opened with it, often several times a day. thankfully they welcome this new method g doing their most distasteful job. the can without a drop spilled, without any rough edges to snag your fingers—all in a couple of seconds! year old child can do it in perfect safety! No wonder women—and men, too—simply go wild over it! And no wonder Speedo representatives often sell to every house in the block and make up to $10 an hour, either spare or full time. SECTION 151 New/ Patented Just A Twist Of The Wrist Banishes Old Style Can Openers to the Scrap Heap invention! Now, all the danger and wastefulness of old-style Now, every home in the a handy little machine. incredible. So I’ve worked out a special advertisin, plan by which you can examine the invention an test it without risking one penny of your money. Generous Free Test Offer All I ask you to do is to fill Yet prac- Imagine, then, how —this automatic way of AGENTS Full or Part Time We instruct you and fur- nish everything. Under our lan Ornoff of Va. made SAMPLE OFFER. out and mail the coupon below. You do not obligate yourself in an: ae whatever. Get my Free offer. All you risk is a 2c stamp— so grab your pencil and shoot me the coupon right now. Address: CENTRAL STATES MFG. CO., oie ’ ° 265 in a week. G . ¥ i New ‘Million Dollar’ Machine Wyo., made $18.75 in’ Bap. SOR, CS ey ae nae The Speedo holds the can— hours. Barclay, N. Y.. L.. ge - jf)- opens it—flips up the lid so you ee ae ¥ “| can grab it—and gives you back details and FREE TEST Central States Mfg.Co., Dept.E-842 I 4500 Mary Avenue, St. Louis, Mo. | It’s so easy even a ten- Frankly, I realize that the facts about this proposition as outlined briefly here may seem almost Yes, rush me the facts and details 1 y | of your FREE TEST OFFER. PROMI. 6 65.6 633.05 00000cdesesetassabaneesssenusso | RBGIGNB. oo 6.0.0:0:0:0:000066056666060600000554550882 J l COs so scatcsactenstssadante BUAOO. cccccccess | (Check here if interested only in one for your [ . Course for men of ambi- Electrical io: \ 24. limited ‘time. Over 5000 men trained. Condensed course in Theoretical and Practical Elec- trical | s including ngineering # «:- ly related subjects: of Mathematics and Mechanical Drawing. Students construct motors, install wiring, test elec- trical machinery. Course designed to be completed one college year. BLISS ELECTRICAL SCHOOL Prepare for your fession in the most interesting city in the world. Catalog on request. 105 Takoma Ave., Washington, D.C. ¥i in a few months of practical instruction. No books or classes. No mechanical experience necessary. y pay- ment terms. Uncrowded field, Work your way through school. Our schools located in Phila., Boston, Cleve- land, Detroit, and Chicago. Write for FREE BOOK. MSS a ircuces Aeomse”* “Dont, 220° Cnicages AGENTS 500% PROFIT GENUINE GOLD LEAF LETTERS Guaranteed to never tarnish, Anyone can put them on stores and Office windows, Enormous demand, large profits, Paul Clark says: smallest day $28.70. R.L. Reel made $920 intwo months. 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152 DRAFTING ee =, Learn at Home DraFtinG is one of the best professions a young man can choose because it pays good salaries and it is the stepping stone to even better positions. Many leading architects, mechanical engineers and electrical engi- neers got their start at the drafting board. There is no easier way to learn Drafting than through the home-study courses of the International Correspondence Schools. The practical value of these courses is shown by the success of I. C. S. students and also by the fact that employers are constantly writ- ing us for trained men. We receive more calls for I. C. S. draftsmen than for gradu- ates of any other course. F. E. King was “‘a poorly paid clerk” when he en- rolled for the I. C. S. Drafting Course. By study, industry, and perseverance he ame Chief Drafts- man of the U. S. Steel Furniture Company, of Syra- cuse. He is now earning more in a day than he used to earn in a week. A. J. Hutchins became Chief Draftsman for the American Strawboard Company and increased his salary 300% —also as a result of I. C. S. Training. There is no doubt that Drafting offers a real oppor- tunity to ambitious men and it will pay you to investigate it. Just mark and mail the coupon and we'll glady send you a booklet telling all about the I. ©. S. courses in Drafting or other subject in which you are interested. INTERNATIONAL CORRESPONDENCE SCHOOLS Box 7626-F, Seranton, Penna. Without cost or obligation on my part, please send me one of your booklets and tell me how I can qualify for the position or in the subject before which I have marked an X: C0 Mechanical Drawing Sheet Metal Worker’s Course Draftsman’s Course Sheet Metal Pattern Drafting Boilermaker’s Covrse Boilermaker’s Laying Out Structural Drafting Ship Drafting Architectural Drawing Illustrating & Designing Mechanical Engineer Machinist Electrical Engineer Toolmaker Civil Engineer Iron and Steel Worker Steam Engineer Patternmaker Structural Engineer Foundryman Automobile Mechanic Architect’s Blueprint Reading Electrician Apprentice Trades Salesmanship Architectural Engineer Surveyor Concrete Builder Contractor and Builder Business Management Traffic Management Advertising Bookkeeper Business English Private Secretary Civil Service Spanish and French Mathematics Common School Subjects High School Subjects world ts kinking, snarling and pte of po) aye electric iron cords. "Housewives and business men buy 1 to 50. Every Neverknot Salesman is giv- en a complete Neverknot Switch FREE. This MONEY MAKING OPPORTUNITIES SECTION | from a wire terminal in the middle of the flame. a Eyes That Never Sleep (Continued from page 52) broken, and a spring or other lever released. Before it will operate machinery, however, the feeble electric current of the eye has to be amplified millions of times. Just as a man, by pressing a button, can set off a blast that will move a mountain, so the eye’s infinitesimal power will operate sensitive electric relays that magnify it a millionfold. One of the most remarkable of these rélays is the “Knowles grid-glow tube,”’ a vacuum tube filled with neon gas that burns with a pinkish glow. ‘So sensitive is the tube, it is said, that “‘a fortieth of a fly power” can operate it. A few months ago an automobile salesroom in New York City displayed a unique adver- tisement. “‘Place your finger on the red spot on the show window,” a sign advised. At the slightest touch, as directed, a driverless car in the showroom rolled up an inclined runway as if some unseen hand were moving it. Crowds that gathered to watch -the- demon- stration blocked traffic. [HE secret of the trick lay in an inconspicu- ous piece of tinfoil pasted on the inside of the window, from which led a wire to a Knowles grid-glow tube. Merely placing a finger on the | outside of the window opposite the foil was sufficient to disturb the electric charge of the tube and to start it working. Its power, amplified ten million times, ran an electric motor in the car. Even professional magicians are fooled by the scientific wonder. When these masters of sleight-of-hand met at a recent convention, a guest exhibited a little magic of his own. His equipment was simple; two ordinary look- ing black boxes, and a pack of cards. “Choose a card,” he invited, “and remem- ber which one it was.” By the old trick.ef using a “forcing’’ deck he made the neaiest magician select the card he wanted—the three of clubs. ‘“‘Now,’’ he continued, “‘ gut your hand over this black box and see a appens.” The magician did as directed. His eyes opened wide in astonishment. From the other box slowly rose a huge card upon which were engraved three clubs. The guest was a member of the physics de- partment of Columbia University. Within the first black box was a grid-glow tube that, at the approach of a hand, had set in motion the electric machinery that produced the phantom card. “You magicians might read up on your science and learn a few new tricks,’’ was the Columbia man’s comment. [Serer magic, too, is that of the grid- glow tube. It will safeguard an oil-burner by making it impossible to turn on the oil unless the pilot is lit—thus avoiding a possible explosion. In most oil burners with gas pilot lights the safety lock is a thermostatic device, operated by the flame’s heat; but such a cevice requires several seconds to operate. The electric device clicks off the oil valve in- stantly if the pilot flame goes out. Its source of power is the tiny current that the hot gases of a flame will conduct to the metal casing One, manufacturer recently installed such a device on an annealing oven in his Newark, N. J., shop. It worked splendidly, except that whenever anyone approached within two or three feet of the furnace the “robot” turned off the oil! A few changes in the elec- trical connections corrected this ultra-sensi- tiveness. An inquisitive hand approaching the tube, or any tin foil strip connected to it, is sufficient to set off an alarm—a fact that recommends it as a burglar alarm in jewelers’ shops, for instance, where a strip of foil beneath a show- case would set off a siren if any night intruder placed a hand on the case. PATENTS TRADE-MARKS SERVICE Without charge or obligation, we will inform you on any questions you ma: put to us touching on patent, trade-mar and copyright law. You may ask: “Should I protect myself by patent, or register the trade-mark or copyright laws? What kind of a patent should I obtain?” ang If many other questions that may oceur to |i you. These are vital points to consider |} and questions will be cheerfully answered, Don’t Lose Your Rights \ To Patent Protection Before disclosing your invention to any- ff one send for blank form “EVIDENCE | OF CONCEPTION” to be signed and wit. nessed. As registered patent attorneys represent hundreds of inventors all iit over the United States and Canada in the advancement of inventions. The form “Evidence of Conception,” sample, instrue- tions relating to obtaining of patents and schedule of fees sent upon request. LANCASTER & ALLWINE 274 Ouray Building Washington, D.C. MASON, FENWICK & LAWRENCE PATENT LAWYERS 600 F. St., N. W., Washington, D. C, Estb. over sixty years. Send sketches, Electrical and Chemical Inventions carefully handled, Practice before the U. S. Courts and the Patent Office, Prompt and careful service. Write Us. TRA DE MARKS REGISTERED INVENTORS Write for FREE Booklet “Suggestions from Manufacturers on What to Invent.” ADAM FISHER MFG. CO. 183-D Enright 38 St. Louis, Mo. PATENTS Trade-marks, Copyrights, Patent Litigation, Handbook with illustrations, 100 mechanical movements. Sent free on request. ALBERT E. DIETERICH Formerly ber E. ining Corp. U. S. Patent Office Registered Patent Lawyer and Solicitor 30 years’ experience 681-A Ouray Bldg. Washington, D. C. PATENTS HIGHEST REFERENCES BOOKLET FREE T RESUL PROMPTNESS ASSURED B Send drawing or model for examination and advice WATSON E. COLEMAN, Patent Lawyer 724 Ninth Strect Washington, D. C. HB PAINT QUICK, EASY PROFITS! Practically no investment. Small space required. St demand and BIG PROFITS Tre finishing autos, furniture—paint- ing houses and barns with HB quick sora Re with brushes, Pare fr Ba enny, monthly payments 30 detalles HOBART BROS. CO. Box P591. Trov. Ohia QUICHLY PAYS FOR. ITSELF. ——_ A definite program for getting ahead financially will be found on page four of this issue. me ent emene.a ae ern oa Ss fae ee 6 SS = 3 =e Dee chock oe Oo eee _-2

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AY, 1999 Mix, 1929 MONEY MAKING OPPORTUNITIES SECTION 153 At the right is a view of my draft- ing and §p tion offices where a large staff of experienced expertsare in my constant employ.

All drawings and spec- ifications are pre-

My —-" pared under my per- Just Across Street _. sonal supervision. From Se US. Pat. “sly GER C = oe ne Protect Your Ideas Take the First Step Today—<Action Counts nventors If you have a useful, practical, novel idea for any new article or for an S improvement on an old one, you should communicate with a competent . B Registered Patent Attorney AT ONCE. Every year thousands of applica- 4 tions for patents are filed in the U. S. Patent Office. Frequently two or more applications are made for the same or substantially the same idea (even though the inventors may live in different sections of the country ks —

time. Get in touch with me at once by mailin, the coupon below. Prompt, Careful, Efficient Service This large, experienced organization devotes its entire time and attention to patent and trademark cases. Our offices are directly across the street from the U. S. Patent Office. We understand the technicalities of patent and be entirely unknown to one another). In such a case, the burden of ee NCE » C. 8. ndled, Office, ED proof rests upon the last application filed. Delays of even a few days in and filing the application sometimes mean the Ics of a patent. So lose no Mo.

ee, — i ee ; law. We know the rules and requirements of the Patent Office. We can £0 O Q 4 proceed in the quickest, safest and best ways in preparing an application — 2 ee BT 4 - P “pod, r

; if for a patent covering your idea. Our success has been built on the , ah aes ATr, ~4 strength of careful, efficient, satisfactory service to inventors and trade- ; wt: . £A 7 F : mark owners located in every state in the Union. faa me: ; 3 i ae ay ij ee Sw r hes Strict Secrecy Preserved— Write pe — coer / a Me in Confidence a / All communications, sketches, drawings, etc., are held in strictest confidence in strong,

Office steel, fireproof files, which are accessible only to authorized members of my staff. re ‘ Feel free to write me fully and frankly. Itis probable that I can help you. Highest \ 5 f D.C. references. But FIRST—clip the coupon and get my free book. Do THAT right \ : per a now. No Charge for Information On How to Proceed The booklet shown here contains valuable information relating t procedure that every inventor should have. And with it I will Ah gon my Record of Invention” form, on which you can sketch your idea and establish its date before a witness. Such evidence may later prove valu- able to you. Simply mail the coupon and I will send you the booklet, and the “Record of Invention” form, together with detailed information on how eeeneeee and oe costs a Do this NOW. No need to lose a ute’s time. e coupon will brin ou com i i i Sileet denne oe non ll gy plete information entirely Clarence A. O’Brien Registered Patent Attorney Member of Bar of: Supreme Court of the United States; Court of Appeals, District of Columbia; S District of Columbia; United States Count of Giaian” PRACTICE CONFINED EXCLUSIVELY TO PATENTS, TRADEMARKS AND COPYRIGHTS OD rN Mail this Coupon How CLARENCE A. O’BRIEN Registered Patent Attorney 88-G Security Savings and Commercial Bank Bldg., Washington, D. C. —OR— Suite 1106 Woolworth Blidg., New York City. magenta) Wee vgrae eS stew mews eRe rm org

Please send me your free book, ‘“‘How to Obtain a Patent,” and your “Record of Invention’ form without any cost or obligation on my part. (Important: Write Plainly and Address Office Nearest You)

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MONEY MAKING OPPORTUNITIES SECTION Expert Help and Inside Information for Builders! Up-to-date, complete Trade Guides and Trade References—handy, pocket size; fully illus behind! Be a boss! for Guides coverin: a month if satisfied. your CARPENTE \udels Carpenters Guides. (4 vols.$6.) Ex- lains how to handle every kind of Aan nag ide or outside work, —_ 5 calculations and beasy. Newshort-cuts, modern D suilders and contractors questions answered. Steel a solved. A practical Guide and help- hand for every carpenter; easy, ick methods of work that help you to be a leader. PLUMBERS cues * Audels Guides. (4 vols. $6.) 4 explaining the theory and practice » heating, steamfitting, gasfitting 2° p> are and othe: the Trade and tudy course, Fully illustrated, coment, date, with comple rs" Code M/ ASONS cnt: $6 rol #9) Brey Trade; inclu outline of steel constru nm ELECTRICITY sa ’4 Handy Book reliable authority and handy hel for e ical Worker, covering Wiri 4 Radio Caleula. A Hie ing 10, Armatures Maintenance, Motors, Batteries. A complete Stud: urse and y Reference in one handy Guide {or Plecrricien, Rnpingerand student ADUDEL & CO. 65 W. 23 ST. New York City Please mail me for inati TRIAL § the books marked (x) below. If I find books satisfactory, I will mail $1 in7 days COUPON on each set ordered and will mail $1 a month on om set ordered until I have PENTERS ( | MASONS FOURGUIDES $6 FOUR GUIDES $6 PLUMBERS Cc] ELECTRICIANS FOUR GUIDES $6 HANDY GUIDE $4 Name Address, Occupation Employed by. attractive professions © ART and ADVERTISING Meyer Both Company, a dominant factor for 28 years in art and advertis- ing service, With over 5,000 clients thruout the English speaking world, offers practical instruction in these two fascinating fields open to both men and women. This instruction— based upon so wide an experience— translates the maze of vague theo into demonstrated fact. Individua ized home study instruction. If in- terested in a career in either of these well paid professions send for free book on (1) Art (...) or (2) Advertis- ing (..+) MEYER BOTH COMPANY Dept. 35crcaco MMSCHIGAN BLYD. AT 20TH. ST. PO PLS Ne NA PL LAA POLL Advice for POPULAR SCIENCE MONTHLY readers regarding safe and profitable investments. See Page 4. A Bigger Ditch Than the Panama (Continued from page 25) sixteen-mile-wide barrier of hills and rugged peaks bars the lake from the Pacific. Through this wall engineers would have to cut a passage. Vicious sharks and swordfish infesting Lake Nicaragua will menace the masters of dredges and dynamite hewing the canal. The present proposal is to run a forty-four-mile canal east- ward from the Atlantic mouth of the San Juan River, separated from it at points by dikes. Four locks would raise vessels making the ascent. A dam at Conchuda would convert the upper fifty miles of the river into an arm of Lake Nicaragua. Across the shallow lake, which has only a few spots as deep as 200 feet, a channel would be dredged and through it ships would steam to the western shore. There the canal route would pierce the Continental Divide and drop through four locks to the level of the Pacific Ocean. LTERNATIVE routes have been sug- gested. With its option to build the canal, the U. S. Government acquired the right to erect a naval station at the Gulf of Fonseca, on the Pacific Ocean, where one proposed canal route might terminate after traversing Lake Nicaragua and its connecting lake, Managua, seen just above it in the ac- companying map. Two other routes would cut a waterway from Lake Managua directly westward to the sea. For twenty-five years a heated controversy has raged between the advocates of the Nicaragua canal and its critics, and always the discussion has centered about volcanoes. On an island in Lake Nicaragua not ten miles from the proposed canal route stands the ever- smoking cone of Ometepe, which erupted four years ago. Ten miles south of the lake’s lower end, just across the border in Costa Rica, is the grumbling volcano, Orosi. Towering over the northern end of Lake Managua, Mt. Momotombo threatens the northern route to the Gulf of Fonseca. Should any one of these volcanoes suddenly become violently active, critics point out, a billion-dollar canal might be put out of business in a few minutes. ‘THE Nicaragua Canal would take from eighteen to thirty-six hours to traverse, as compared with six to eight at Panama. But it would clip a day’s sailing time from New York to San Francisco, and about two days from New Orleans to the west coast. Two harbors would need to be created for the Nicaragua project, and a 120-mile railroad built. At Panama two fair harbors already existed, and a railroad was-taken over. The entire Panama route is about forty-seven miles long; the Nicaragua route, about 183 miles. There are the facts, and it is up to Uncle Sam to decide whether he is going to tackle the billion-dollar job. Engineers agree that if work started tomorrow, the canal would be ready for ships only by 1940. By that time, observers ask, will even an enlarged Panama Canal suffice for increasing commerce? Research Two Miles High ESEARCH that is bound to advance avia- tion will be conducted in a new inter- national laboratory being built on Sprinx Peak, an 11,500-foot-high spur of the Jungfrau, one of the tallest mountains in the Swiss Alps. Here scientists will study the effects of rarefied air and of the sun’s rays upon human beings, as well as animals and plants, in high altitudes. Other research will be conducted at the unique institution, which is being established under the auspices of the International Educa- tion Board of the Rockefeller Foundation, the German Kaiser Wilhelm Institute, and other scientific organizations. He Kept the Job He Liked? —and increased his salary 73% W. A. Day, of Woonsocket, R. L, wan money. But he liked his job—didn’t t —made up his mind to get more money he was. He enrolled for LaSalle hom: ing in Higher Accountancy—followed it with Business Correspondence—is now pursuing training in Business Management. “In actual have received a salary-increase of exactly 733 cent since, the date of my first enrollment,” Hg Mee but I ey this equal to his neat i e average case, for ned :, without cha ing my position.” = ow much is ment—within S comparatively few monthet Tings outlined in a fascinating book, ‘‘Ten Years’ On i ring it to you FREE, business field which ——~ A “ Shia For the brighter future, elip and malt the coupon NOW. . — — —Find Yourself Thru LaSalle lame mun on LASALLE EXTENSION UNIVERSITY The World’s Largest Business Training Institution Dept. 583-R Gentlemen: Send without obligation to me infor mation regarding course indicated below: ar ang amen OCommercial Law ern esmanship OMod jiness Corre OHigher Accountancy epondence _" OTraffic Management OExpert Bookkeeping OC. P. A. Coaching ORailway Station emen' OBusiness English OLaw: Degree of LL. B. OModern Foremanship OCommercial Spanish OPersonnel Management UEffective Speaking Olndustrial Management OStenotypy—S OBanking and Finance OTelegraphy OCredit and Collection Correspondence “ee Name ... Present Position Add: PE eT IS, 1000*SznE Ss yy Our famous home-study Poultry Course teaches how to get bigger hatches, cut feed bills, avoid losses and 1 other money-mak- ing secrets. Methods us: by__ successful Poultry raisers the world over. tells all about Course and big men behind it. Write today for your free copy. NATIONAL POULTRY INSTITUTE Dept. 413-J Washington, D.C. Learn Cartooning At Home—in Your Spare Time The famous Picture Chart Method of teaching original drawing has opened the door of success for hun- dreds of beginners. Whether you think you have talent or not, send for sample chart to test your abil- ity, and examples of the work of students earning from $50 to $300 k. Please state your age. week THE LANDONSCHOOL 1451 National Bidg., Cleveland, 0. -Print YourO Cards, stationery, labels, paper, circulars, tags, menus, ete. Save money and time, cut cost in p \ \ SY Print for Others, #] ay rN All easy, rules sent. aN) cates of presses, wen paper, cards, envelopes, paper cutters. EXcersioR The Kelsey Co., P-33, Meriden, Cons A Monthly Chemical Magazine Latest chemical news, experiments, formulas, recent advancements in medi cine, new uses for X-rays, ultre-violet light, radium, etc., every month. 1 total copies (back issues), 30 ts. 1, per year. ree chart and book catalog to immediate yearly subscribers. POPULAR CHEMISTRY Dept. MY-D. Swedesboro, N.J POPULAR C= [e)] CHEMISTRY

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&- a) wo 3g ibis oe east, a ik te New York Office Suite 1007 Woolworth Bldg. Philadelphia, Pa., Office Suite 203 Liberty Bldg. Washington, D. C., Office Victor Bldg. Nearly opposite U. S. Patent Office MONEY MAKING OPPORTUNITIES SECTION OUR OFFER ¢ FORTHE PROTECTION e OF YOUR INVENTION YOUR FIRST STEP—The inventor should write for our blank form “RECORD OF INVENTION.” Before disclosing your inven- tion, a sketch and description should be made on the blank sheets of our “‘Record of Inven- tion” and signed by the inventor and wit- nessed, sent to us, and we will place it in our » fireproof secret files. We will also give our opinion as to whether the invention comes within the Patent Office definition of a patent- able invention. This “Record of Invention”’ will serve as ‘‘proef of conception” until the case can be filed in the Patent Office. There is no charge or obligation for this service Our Five Books Mailed Chicago, Ill., Office Suite 1110 Tacoma Blde. Free to Inventors Our Illustrated Guide Book HOW TO OBTAIN A PATENT Contains full instructions regarding U. S. Patents. Our Methods, Terms, and 100 Mechanical Move- ments illustrated and described. OUR TRADE-MARK BOOK Shows value and necessity of Trade-Mark Protec- tion. Information regarding TRADE-MARKS AND UNFAIR COMPETITION IN TRADE. OUR FOREIGN BOOK We have Direct Agencies in Foreign Countries, and se- cure Foreign Patents in shortest time and at lowest cost. PROGRESS OF INVENTION Description of World’s Most Pressing Problems by Leading Scientists and Inventors Pittsburgh, Pa., Office Suite 514 Empire Bldg. ALL COMMUNICATIONS AND DATASTRICTLY CONFIDENTIAL INTERFERENCE AND INFRINGEMENT SUITS PROSECUTED DELAYS ARE DANGEROUS IN PATENT MATTERS WHEN THE INVENTOR WISHES APPLICATION FILED WITHOUT DELAY HE SHOULD HAVE HIS CASE MADE SPE- CIAL IN OUR OFFICE to save correspondence, secure protection and early filing date in Patent Office. He should send us a model, sketch or photograph with a description of his invention together with $25.00 on account. We will make an examination of the U. S. Patent Office records to learn whether the invention is patentable. If it is we will prepare the official drawings immediately and forward them for approval and execu- tion. If the invention is not patentable we will return the fee less the cost of the examination. Our Large, Comprehensive Organization has been established for 30 years and offers Prompt, Efficient and Personal Service by experienced Patent Lawyers and Draftsmen. We shall be glad to have you consult us or to answer any questions in regard to Patents, Trademarks or Copyrights without charge or obligation. PAYMENT OF FEES IN INSTALLMENTS It is not necessary that the total cost for the preparation and prosecution of a patent be paid in one payment. Our custom is to permit our clients to pay for their applications in three installments as the preparation of the application progresses in our office. This plan makes the payments easy, for the inventor. Highest References—Prompt Service—Reasonable Terms WRITE TODAY = = IVICTOR J. EVANS & Co., Registered Patent Attorneys : Established 1898 Main Offices: 694 Ninth St., Washington, D. C. Gentlemen: Please send me FREE OF CHARGE your | books as described above. FREE COUPON le 3 aca — San Francisco, Cal., Office Suite 1010 Hobart Bldg. | l I | | FN ETOP rere Py ei of, ere ne ceemaaemmentinnmmmecmmme epee oss serene het por reenter ee ae Vane 2

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The only man who could talk to the Superintendent “Soon after I began studying,” a student wrote to us the other day, “‘we had a change in management at =. I certainly was glad then that I had de- cided to study in my spare time. For, thanks to my I. C. S. course, I was the only man in the organiza- tion who could talk to the Superintendent in his own Fi unguage. As a result, I was promoted over men who had been here from ten to twenty years. My salary has been increased 90 per cent in the last ten months.” That’s a true story of what just one I. C. S. student has done. There are thousands of others. Every mail brings letters from men and women telling of promotions and in- creases in salary due directly to spare-time study. One hour a day, spent with the I. C. S. in the quiet of your own home, will prepare you for success in the work you like best. Yes, it will! Put it up to us to prove it. Mail this Coupon for Free Booklet INTERNATIONAL CORRESPONDENCE SCHOOLS “The Universal University’ Box 7625-F, Seranton, Penna. Without cost or obligation on my part, please send me a copy of your 48-page booklet, “Whe Wins and Why,” and tell me how I can qualify for the position, or in the subject, before which I have marked an X: TECHNICAL AND INDUSTRIAL COURSES Architect ] Automobile Work Architectural Draftsman (] Aviation Engines Building Foreman Plumber and Steam Fitter Concrete Builder Plumbing Inspector Contractor and Builder Foreman Plumber Structural Draftsman Heating and Ventilation Structural Engineer Sheet-Metal Worker Electrical Engineer Steam Engineer Electrical Contractor Marine Engineer Electric Wiring Refrigeration Engineer Electric Lighting R. RB. Positions Electric Car Running Highway Engineer Telegraph Engineer Chemistry Tele Work Pharmacy Coal Mining Engineer Navigation [) Assayer Iron and Steel Worker Textile Overseer or Supt. Cotton Manufacturing Woolen Manufacturing 4 Agriculture () Fruit Growing Mechanical Engineer Mechanical Draftsman Machine Shop Practice ‘Toolmaker Patternmaker Civil Engineer Surveying and Mapping Bridge Engineer Poultry’ Farming Gas Engine Operating Mathematics [] Radio BUSINESS TRAINING COURSES Business Management Business Correspondence Industrial Management Show Card and Sign Personnel Management Lettering Traffic Management Stenography and Typing Accounting and C. P. A, Lj English Civil Service oaching Cost Accounting Railway Mail Clerk

lSookkeeping Mail Carrier Secretarial Work Grade School Subjects Spanish [ French High School Subjects Salesmanship Illustrating () Cartooning Advert Lumber Dealer PII dsidilhsihdticipnndtistuntesdnnnsetecsecsssseccece Street SITTIN censtedacencaestensnsécsenssesnsecensccosesscocnsvocesosoccesocccscececeescocese ieiln Radio Service, Radio Engineering, Broad-}? casting, Television, Station-operation and Radio Merchandising. Get into this wonder- tel, iest-srowing field & J )W! Good pay, big opportuniti Become trained Radio-Technician in 3 months or the didly equipped school (which Station WISN Splen- Complete practical course covers Radio Brot ae). Merchandising and Television. The onl radio au: in the country approved by a radio trade fourse Graduates receive ‘Class B”’ license without e tion. Moderate tuition fee. Our illustrated yg log gives details of how to become a trained —- radio technician in 90 days. Send for it FREE today. No obligation. BOOK SCHODL °f ENGINEERING

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Stranded—Seven Miles Up! (Continued from page 156) : from the field in an automobile. — rie to think that because aviators travel fast, they like speed. That may be all | right in the air—but | won't ride more than once | with the wild driver who tries to show off his car's with me in it. | Two things of interest I learned about the airman’s code. “In the first place,” Captain | Streett said, “if a pilot worried about what | might happen to him in the air, he wouldn't fly. There are too many unnerving things that might happen but generally don’t. So a pilot doesn't worry. If a pilot doesn’t feel competent tocope with any emergency, he has no business ina plane.” ; And the second is that memory of an un- nerving experience is left behind almost at the moment a pilot’s plane touches its landing wheels to earth. “You may miss the wings of another plane by inches, flying in formation,” said Streett, “‘and say to the fellows when you come down, ‘Well boys, I just picked up two or three new gray hairs.’ But that’s the end of | it. Of course, the pilot who says he’s never been | scared is lying. I’ve been scared so many times | myself that I’ve lost count.” | (APTAIN STREETT never expected to be | a flyer. At eighteen or nineteen he was studying medicine at Tulane University—and building model airplanes as a spare-time hobby. Aviation at that time was less of a profession than a dare-devil stunt. It appealed to young blood as a great adventure, and young Streett yearned to fly. His father frowned upon the

Two things happened, in quick succession, that had a profound effect on Captain Streett’s career. His father died, in 1913. Then came the World War. “We young fellows saw other Americans going to France to join the Lafayette Escadrille, a branch of the French foreign legion,”’ he said. “Bill Thaw was over there, Raoul Lufberry had gone from Connecticut, Norman Prince from Boston, and Kiffin Rockwell from Con- necticut. That settled it; I had to be a flyer, too. I quit the job I had then, as a purser with the Merchant Marine, and joined the Aviation Section of the U. S. Army Signal Corps—the tiny nucleus that was later to become the Air Corps. “My mother didn’t object. She seemed to think I'd have to work out my own life for myself, whatever way I chose—a good sport, don’t you think? Naturally, I didn’t have much trouble thinking up good reasons why I

should be an aviator. “ap wo months of ground training at New- port News, and I made my first solo flight. October, 1917, found me on my way to France. I wound up at Issoudun, a great aviation training school south of the Loire Valley, where I remained as flying instructor until the signing of the Armistice. After that, I was with the Army of Occupation, returning to this country in 1919. The following year, the Alaskan expedition took me north.” It is hard, in 1929, to conceive what it meant to lead the first aerial expedition from New York to Nome, Alaska. Landing fields, in those days, were often transformed corn- fields. Only as far as Erie, Pa., one of the four De Havillands that blazed the trail to the Yukon became stuck in mud so thick that even the horses attempting to pull it out became bogged! Yet all four planes arrived in Nome, Alaska, in fifty-three and a half flying hours from New York, the elapsed time being forty days. And the return journey to New York was completed in a total flying time of only 112 flying hours. For this trip Captain Streett re- ceived the Distinguished Flying Cross. For Some years after, he was in the office of the Chief of Air C orps at Washington, D. C. Tn 1925 Streett entered (Continued on page 158)

MONEY MAKING OPPORTUNITIES SECTION 157

ScIENTIFIC AMERICAN BUILDING 24 W. 40th St., New York City Tower BuiLpING Chicago, Ill.

Van Noys BuiLpInG Los Angeles, Cal. CrQOIZD Books and Information on Patents and Trade-Marks by Request Associates in all Foreign Countries PATENT TRADE-MARKS +, FOREIGN PATENTS MUNN & CO. PATENT ATTORNEYS Associated since 1846 with the Scientific American DESIGNS ScIENTIFIC AMERICAN BuILDING Washington, D. C. Hosart BuiLtpDInG San Francisco, Cal.

who derive larg- est profits know and heed certain simple but vital facts before applying for Patents. Our book Patent-Sense gives those facts; sent free. Write LACEY & LACEY, 648 F St., Washington, D. C. Established 1869

$300,000 FOR THIS INVENTION That's what Eastman Kodak paid for the Autographic idea. Thousands of other inventions are needed and offer enormous . eo¥Y for earning fortunes. you are of an inventive turn of mind why not con- centrate on things that are really NEEDED. Get Raymond Yates's new book. ‘6 1000 Needed Inventions’’ Costs only $1.25 and may start you thinking along the right lines. You'll get nowhere just fussing around. Concentration on what the industries need, and on what the public wants. Mr. Yates’s book tells you what these things are. Send no money. Just write postal. Pay mail man $1.25 plus postage when book arrives. Your money back if you want it. This offer limited. Write now and get on the right track. Outside U. S., $1.44. Cash with order. Address. Bareau of Inventive Science Dept- 25 Wisner Building Rochester, N. Y.

TO THE MAN WITH AN IDEA PATENTS Procured. Trade Marks Registered. —A comprehensive, experienced, prompt service for the protection and development of your ideas. Preliminary advice gladly furnished without charge. Booklet of information and form for disclosing idea free on request. IRVING L. McCATHRAN PATENT LAWYER Formerly with and successor to Richard B. 705 International Bldg., Washington, D.C, 41-D, Park Row New York City TRADE -MARKS

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A definite program for getting ahead financially will be found on page four of this issue.

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I NVENTO RS YOUR IDEAS Send for our Guide Book, HOW TO GET YOUR PATENT, and Evidence of Invention Blank, sent Free on request. Send model or sketch and description PROTECT Tells

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American School, Chicago Charter. The School was chartered in 1887 as an educational institution. Not for Profit. Being conducted as an educational institution, not for profit, it is exempt from all income taxes. Satisfaction Guaranteed. The School guarantees every graduate satisfac- tory instruction or his money back. Home-Study Council. The American School, like the home-study depart- ments of colleges and universities, is not a member of the National Home- Study Council. Get Ready for a Better Position

You want to earn big money—steady | promotion. Are you prepared for the position ahead of you? For a more re- sponsible position at better pay, a fairly good education is necessary. To write a sensible business letter, to prepare estimates, to figure costs, and to prepare reports, you must have a certain amount of training. Many con- cerns will not hire men who are barred from promotion by the lack of elementary education. If You Have Not Completed High School and are under thirty, we urge you to do so at once. If you can’t go back to your local high school, take our sim- plified High School Course. We use the same standard textbooks as your local high school and will give you equivalent training. Get at once the foundation training required for suc- cess and big money. YOU CAN DO IT. If You Have Completed High School you are ready to specialize in some well-paid trade or profession: Archi- tecture— Drafting — Electrical — Me- chanical— Business— Automotive En- gineering, etc. A knowledge of higher grade work brings promotion. The work you are doing today fits you to continue doing it. Promotion doesn’t mean longer hours—but shorter hours and more pleasant work. It is the re- ward of the man who has fitted him- self for the more important positions. Qualify for a Better Position To prove to you how easily and quickly you can learn by our home-study method, we want to send you samples of our special lesson papers. We guar- antee you satisfactory instruction or your money back on graduation. Let us show you how to get on the road to success. Write today. It costs you nothing but a stamp. American School Dept. H-575, Drexel Ave. at 58 St., Chicago

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Stranded—Seven Miles Up! (Continued from page 157) the Air Service Tactical School as a student, and went from there to Selfridge Field, Mt. Clemens, Mich., to join the First Pursuit Group. He was back in the air again. Thence he went to Wright Field. Here, while he has been in charge of flying tests, Captain Streett told me, many exciting dramas of the air have been written. Just the other day, for instance, Lieut. Julian B. Haddon fell four miles unconscious in a plane he was testing at high altitude. He recovered his senses at 10,000 feet to find the plane afire, and jumped with his parachute just in time to save his life. “*Speaking of fire thrillers,’’ Captain Streett said, “let me tell you of one of the queerest accidents of all, that Lieut. J. T. Hutchinson had not long ago. He took up a new bomber, of an experimental type, to see how it would behave in the air. It didn’t take him long to find out. In the middle of a climb for altitude, smoke shot out of the engine. Hutchinson peered over the dashboard, saw a secthing mass of flames, and decided the cockpit was no place for him. A second later he was swinging to earth at the end of his parachute. “HEN, looking back at the plane he had left, he saw a sight that sent cold shivers up and down his spine. The pilotless plane, now in flames, had swung about nose down and was headed straight for him! “That was the start of a hair-raising race to earth. Helpless at the end of his parachute, Hutchinson alternately swore and prayed that the fiery torch wouldn’t hit him, crumpling or igniting his flimsy ’chute of silk. Around and around him spiraled the burning plane, at times so close that he could feel the heat on his perspiring brow. The race ended safely, as luck would have it. Hutchinson hit Wright Field with a jolt, and the plane crashed only a few yards away, a charred ruin.”’ Spending more than half the time in the air, Captain Streett has aided in important avia- tion research. Besides the experiment in taking high-altitude photographs, he helped Lieut. A. C. Foulk, in charge of the Air Corps’ Matériel Division’s Parachute Unit, to find out how strong a parachute needs to be made. Hitherto no one had known whether it was safe for an airman to fall thousands of feet before opening his ’chute, instead of counting a few seconds and pulling the rip cord that unfurled it. How fast does a man fall? That question was answered by dropping dummies from a plane piloted by Captain Streett. They were the size and shape of a man, and carried flares by which their fall could be traced at night. A camera set up on the ground, with a shutter that winked at one-second intervals, took pictures of the dummy’s path to check the distance it fell in each interval. The results were sur- | prising. FTER a man has fallen for about 1,600 feet, the tests showed, he doesn’t go any faster! In other words, if one man were to leap from the top of the Eiffel Tower, and another to jump from a plane four miles high—equal to a world’s record parachute jump of 24,000 feet made by Captain Stevens—the two men would be falling nearly at the same speed when they reached the ground. Air resistance produces this remarkable slowing, and even without a parachute the fastest a man can fall is 130 miles an hour. It is a simple matter to design para- chutes for this strain, now that the exact figure is known. And a jumper may delay opening his ’chute as long as he pleases without fear of ripping it. So Captain Streett, in the course of his varied career, has helped revise the law of gravity as far as its practical application is concerned. Just another incident in the life of an aviator whose career has been a series of thrillers and “queer ones.”’ ae.

“How I Licked Wretched Old Age at 63” “I Quit Getting up Nights—Banished Foot and Leg Pains... Got Rid & Rheumatic Pains and _ Constipation - - - Improved Embarrassing Faults . . . Found Renewed Vitality, At 61, I thought I was through. I blamed old but it never occurred to me to actually fight beck f was only half living, getting up nights . . . embar rassed in my own home... constipated .. . egp stantly tormented by aches and pains. At 62 my condition became almost intolerable. I had about given up hope when a doctor recommended treatment. Then at 63, it seemed that I shook off 3 years almost overnight.” Forty — The Danger Age These are the facts, just as I learned them. I 65% of all men, the vital prostate gland slows up soon after 40. No pain is experienced, but as this distressing condition continues, sciatica, backache, severe bladder weakness, constipation, ete., often develop. Prostate Trouble These are frequently the signs of prostate. trouble, Now thousands suffer these handicaps needlessly! Fors Prominent American Scientist after seven of re search, discovered a new, safe way to stimulate the prostate gland to normal health and activity in _— cases. This new hygiene is worthy to be called a achievement of the age. ) A National Institution for Men Past 40 © Its success has been start- ling, its growth rapid. This new hygiene is rapidly gaining in national prominence. The institution in Steubenville has now reached large proportions. Scores and even hundreds of letters pour in every day, and in many cases reported results have been little short of amaz- ing. In case after case, men have reported that they have felt ten years younger in six days. Now physicians in every

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War Gas Fights Peace- Time Foes (Continued from page 24) midst of preparing a meal, unaware that a stray wind has blown out the flame of a gas burner. This was the menace the Chemical Warfare Service set out to end. **Sneeze gas,” a nose-irritating compound of war days, came to mind. In small quantities it is comparatively harmless, but it provokes violent sneezing. Following the Chemical Service's tests, artificial gas companies are beginning to add a small quantity of the “sneeze gas” to every thousand feet of artificial fuel gas. ‘‘Now. if a burner is left on,” General Fries explained, “‘the new gas will cause violent sneezing and so give warning. It is doubly effective, because it will awaken sleeping persons as well. When burning, the sneeze gas gives off no odor.” A new “skunk gas” developed by the Chemical Warfare Service also is being used extensively by gas companies as a warning against leaks. Entirely harmless, its odor, except when burning, is exactly what its name implies. It would discourage any but the most desperate suicide from ending his life by gas. we western farmers vainly fought a one- sided battle against jack rabbits not long ago, another new use for poison gas came into existence. The farmers, watching their crops ravaged by the rabbit invasion, appealed to the Government for aid. The chemical experts had on hand a small quantity of mustard gas, a lung-searing terror of the World War; and, under their direction, the farmers gingerly re- leased it over rabbit trails, where it condensed in droplets upon the ground like dew. In traveling over their accustomed trails the feet of the rabbits picked up the mustard gas. The rabbits licked their feet, according to their habit, and died. That was the end of the rabbit plague. When the war ended, huge supplies of “*hydrocyanic”’ gas became available for peace- time use. The same qualities that had made it a brutal killer in French shells—paralyzing the nervous system and causing a horrible death— made it a splendid fumigating gas for a ship’s hold, in all respects but one. It effectively killed rats and their parasitic fleas, carriers of bubonic plague and typhus fever; but— One day a ship from Australia entered San Francisco harbor, and a Public Health Service inspector climbed aboard to make sure that regulations requiring fumigation had been complied with. They had. Some hours later the inspector was found dead in the hold. Hydrocyanic gas, which gives no warning of its presence, had been used, and traces still remained. HEN several deaths from this cause were reported, General Fries explained, the Chemical Warfare Service tried mixing with the deadly “‘hydrocyanic”’ one of the varieties of tear gas called “cyanogen chloride.”’ After extensive experiments in Army posts and Army bakeries, the mixture was turned over to the Public Health Service for use on ships. It gives timely warning of its presence by the life- saving tears it induces. War poisons are being pressed into service also against plant pests. There is the story, for instance, of Joe Johnson, a war veteran, who found occasion to be grateful for the very gas he had cursed overseas. With congested lungs to cure, and acom- pensation from the Veterans’ Bureau to aid him, Johnson went to Hawaii and embarked on a career as a pineapple grower. It was hard sledding. His capital was small, and crops were disappointing. Other planters, he found, were having similar trouble. Government chemists, called in, found out why. Tiny parasites— “nematodes,” the chemists called them—were

growing on the (Continued on page 160)

159 “‘Here at last is THE BOOK that we of the Radio profession have needed for a long time. It is the best and mest complete hand- book ever published”’ says J. H. Bloomenthal, Chief Radio Operator, U. S. S. B. Steamship “East Side’’. The RADIO MANUAL A Complete Course in Radio Operation In a Single Volume A Handbook for Students Amateurs Operators Inspectors For the first time an entire course of training in one book — the most complete and up- to-date work on radio. Developed simply and clearly from the elemen- tary stage right through all phases of principles, practice, and ap- paratus so that a beginner with no knowledge of elec- tricity may get all he needs either for amateur operation or to qualify for a government license as operator or inspector. Prepared by Official Officer The author, G.E. Sterling, is Radio Inspector and Examining Officer, Radio Division, U. 8. Dept. of Commerce. The book has been edited in detail by Robert S. Kruse for five years Technical Editor of QST, the Magazine of the Radio Relay League. Many other experts as- sisted them. - Elementary Electric- 16 Chapters Cover: eager pg Rime a Motors and Generators; Storage Batteries and Charging Circuits; The Vacuum Tube; Circuits Employed in Vacuum Tube Transmitters; Modu- lating Systems; Wavemeters; Piezo-Electric Os- cillators; Wave Traps; Marine Vacuum Tube Transmitters; Radio Broadcasting Equipment; Are Transmitters; Spark Transmitters; Com- mercial Radio Receivers; Radio Beacons and Di- rection Finders; Radio Laws and Regulations; Handling and Abstracting Traffic. ° never before available New I nf ormation such, as a complete de- scription of the Western Electric 5-Kilowatt Broadcasting Transmitter; description and cir- cuit diagram of Western Electric Superhetero- dyne Radio Receiving Outfit type 6004-C; Navy Standard 2-kilowatt Spark Transmitter; etc.; etc. Every detail up to the minute. Free Examination “The Radio Manual” has just been published. Nearly 700 pages. Profusely illustrated. Bound in Flexible Fabrikoid. The coupon brings the volume for free examination. If you do not agree that it is the best Radio book you have seen, return it and owe nothing. If you keep it, send the price of $6.00 within ten days. Order on this Coupon D. Van Nostrand Co., Ine. 8 Warren St., New York Send me THE RADIO MANUAL for examina- tion. Within ten days after receipt I will either return the volume or send you $6.00, the price in full. (Pop. Sc. M. 5-29) Se ) | A Oe ee eee cee? or ee ee Cheer and GAG: ..i.0.< 0 caine osbscecungs costae

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160 MONEY MAKING OPPORTUNITIES SECTION May iy , Gli Refund Your RRFare War Gas Fights Peace- Learn cil Time Foes an TRI § (Continued from page 159) bR A U £8) pineapple roots and sapping the plants’ vitality. Soon a number of containers arrived from Washington, filled with -“‘chloropicrin’—a quick-evaporating form of tear gas, the same term stuff that had made the ex-soldier’s eyes smart ° of de o on a Papago —_ The “yew were told to - and ut SNS eg bel sprinkle a few drops around each pineapple 4 , tai. plant. Before eat the root ui teallied. B rou, tt Him solve. 3 The parasites were killed, and a healthy crop of pineapples followed. 00 Whe et a op ee 9 por oa me, pe Fe | esses are being develo to end the ravages of 0 ° i in World | weevils that ruin cotton plantations, and pests from ne Single Blade! NWA! SAY Electricity, Autos, | that infest fruit orchards. They are most Another Triumph for KRISS-KROSS, the Fae ( f=] Aviation now pay hun- | effectively sprayed over large areas from air- Patented! Mr. T. Liddle, “of tert Flying ¢ Suis ae planes, with sprayers of the type developed Wrote Recently: “I Have Been Using One a UD ‘the 3 World’s t. | during the war to lay down smoke screens. Shave Every inented and ye tion and est businesses. Billions “Poison gas dope”’ to protect the pilings of ON MY FIRST BLADE!”’ Read Astonish. sae Wi —not millions, but bil- | docks from marine borers is another innovation. pay I ae at Se eee fying f lions of dollars are speni : other 0 in them every year. | It is a compound formed from creosote and a NO wonder KRISS-KROSS. marks such a radie! Where a Choose one of these three | war poison gas known as “diphenylamine- advance in shaving comfort and economy. For The fi now. hlo ina”, poems & 0 wen cent | “S'S last it has captured a secret that has baffled ese ee , peneunes 5 y scientists for years! It actually reproduces mechan Tnited together with several other chemicals. Test | ically the diagonal flip-flop master-barber's stroke the Aer Be Greer Trained pilings treated with it have withstood borers Caen sages — the poenens cutting edge that Red Wi neaieer trained men are | for three years, at this writing. Now the | ‘ndin just 11 seconds you are ready for theamey | | ada Wo dreds of $10,000 a yearmen. | Service has also concocted a “poison paint’’ | slickest shave you ever had! ' Alberto 90,000 in the last 26 years | which keeps a ship’s hull free of barnacles. Get Free Offer in @ SO have come to makes old blades Keener than new—-we are give 1906, — NE of the most striking possibilities of the | an amazing new kind of razor. Instantly adjustable time | . x near future that General Fries suggested | MPa, comes with § new-pigoes blades. intag | tS Coupon 2 me was the se hurling poison gas from | ©Uut and mail the coupon today. to fly « the air to extinguish fires. RHODES KRISS-KROSS Pm | Last summer General Fries, touring the | CORP... | | Dept. E-243 i007, E You Big | West, witnessed first hand the destructive eS entist, FREE | effects of forest fires and the seeming inability : monop! ~y BOOK | of present equipment to cope with them. He probler — a the os of the war the Loui Chemical Warfare Service had perfected a new Chann Only & Months gas thrower to be attached to pt and to flight b Learn in Only 3 Months in Great spray mustard gas in large drops upon enemy Louis | Greer Shops on Large Live Equip- troops. The Armistice prevented its expected who W ment. Vll Pay Your Fare Here, use all along the western front, and left the 1910. FREE of extra cost, then help you to service with a number of useless airplane for ten a Job While Learning. Then I not sprayers on its hands. The only Fit You to get the Big Pay Job, Now, General Fries said, the service is con- HB ONE DAY 2: voting but I'll help YOU HOLDIT. Young sidering loading them with a fire-extinguishing cuss the Se and Old, Educated and Uneducated, In- liquid such as carbon-tetrachloride, familiar Tune 5 ae was hi experienced and Experienced have also as a household solvent, which, when it Start your own big business nor, on Plu found Greer Shops training Easy, evaporates, creates a flame-proof blanket of gas Smet pence eee ae is hea Fascinating and Valuable. and smothers the fire. radio batteries. York = “If the forest service would equip a dozen Mone oR BROS. Write to Fou t = Learn to fly airplanes with the sprayers, they could keep Box P-59, Troy, Ohio Benne 1a a : at my big fires down to a minimum,”’ he said. “At the $1650 THLY - are st ; new flying first report of a conflagration, the ‘air fire ONLY 31639 MONTHLY winne field engines,’ which might be a hundred or two , Grahi j hundred miles away, could take off for the sells { scene. Flying at a low but safe altitude, they Weyz Learn | would spray the flames with the extinguisher. Amer } about | The large drops, which will not break up in the 316.008 0 near In’the Piecr Rey o Fran Romestent: ae. ee ee the fire completely =e for yourself, Experience, special trainiag. : = Manual Vois . nally—Erwin Greer, Pres | the island of Java has just been uncovered Cn ed a Greer College by chemists of the Volcanological Survey of TheElectrician s Wiring Man - . ings, and help a ~~ | the Dutch East Indies. The valley, a natural By F. E. SENGSTOCK, E. E. a, png and ay 2024 So. Wabash Avenue, bowl on the slopes of the volcano Tangkoban Contains all the information needed of t Worl: to Pay Chicago, Illinois Praho, is paved with the bones of animals and for th installati f lighti wa cow Enee> i “Erwin Greer, President’ | lizards that entered and never returned. or the proper insta. os e v re at learaing. Dept.5-L. 2024 So. Wabash Avenue, Inconspicuous vents in the sides of the valley and power systems in houses and othe lee p~ Send Pree base inglinols stow and | were found to be pouring forth a deadly bar- buildings. vr P Ma: belp you ridstails of Special offer, without obliga- | rage of poison gas, hydrogen sulphide. This is It completely covers inside electrical the real Big O Autos Electricity 0 Aviation the evil-smelling gas given off by bad eggs. In wiring and construction in accordance Ohi 4 pibtiiesssrmapsiiocasasnanand small quantities in the atmosphere, it is not | with the National Electric Code. wh | EE dangerous, but in the Java “Death Valley” Pocket size—flexible sinding chit the air contained as much as ten percent of the . “ fumes. This is sufficient, in a few seconds, to 448 pp. Price, $2.50 * jFREE BOOK Siete eee "© | POPULAR SCIENCE MONTHLY Sa 250 Fourth Ave. New York City iss

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Mar, 1929

Back of the Month’s News (Continued from page 47) ginds over the dry land of Southern Russia, miles away. ; Without dust in the air, we would have no beautiful colored sunsets, and no rain. Up to a certain point, it is beneficial. The problem of determining how much dust and smoke the air can contain without injuring the health of those below, is one that science is seeking to

solve. What Has Become of the Pioneer Flyers? N WASHINGTON the other day the Secre- | tary of War gave America’s Distinguished Flying Cross to Orville Wright and, posthu- mously, to his brother Wilbur for their inven- tion and development of the airplane. The flying machine is twenty-five years old. Many other of the pioneers of flight are still alive. Where are they, and what are they doing? The first man to make a public flight in the United States was F. W. Baldwin, who took the Aerial Experiment Association biplane, Red Wing, into the air in 1908. He is in Can- ada working on a new type of motor boat. Alberto Santés-Dumont, who hopped 600 feet in a sort of motored box kite near Paris in 1906, the first flight in Europe, divides his time between France and his large coffee plan-

tation in Brazil. A. V. Roe, first Englishman to fy a British plane in England, is head of acompany making light planes. As early as 1907, Robert Esnault-Pelterie, the French sci- entist, was flying in his curious “R.E.P.” monoplane. He is now trying to solve the problem of interplanetary transportation. Louis Bleriot, whose crossing of the English Channel in 1909 was one of the milestones of flight history, makes planes in France, as does Louis Paulham, the spectacular Farman pilot who won $100,000 in prizes with his biplane in 1910. The year before, he had been working for ten dollars a week as a mechanic. The American pioneer, Glenn Curtiss, is de- voting his time to real estate development in the South. W. Starling Burgess, who in 1908 was hopping his original biplane over a field on Plum Island, off the coast of Massachusetts, is head of a firm of naval architects in New York City. Four of the pilots who won the Gordon Bennett Cup Race, the prewar speed classic, are still alive. All except Curtiss, the first winner, are in the automobile business. Claude Grahame-White, who captured the cup in 1910, sells automobiles in England. Charles T. Weymann, an American who never lived in America (he was born in Haiti and resided in France), won the cup in 1912. His fabric auto- mobile body, based upon an idea obtained in flying, is made in France and England. Maurice Prevost, who took the cup to France in 1913, 1s manager of a garage in Reims, France. Henri Farman, one of the earliest of the brood of European birdmen, is making planes in France with his brother, Maurice, also a pioneer. Gabriel Voison, designer of Farman’s first Voison biplane, is general manager of the oison automobile works, near Paris. _ Many of the flyers who handled the clatter- ing, chain-driven Wright biplanes in early days are still alive. Griffith Brewer, English friend of the Wrights and pilot of the first Wright machine imported into Great Britain, is a pat- ent attorney in London. Harry N. Atwood is head of a manufacturing concern in Monson, Mass. Howard Reinehart, once chief pilot for the Wrights, is running an airport near Dayton, Ohio. Katherine Stinson, one of the few women who mastered the slow-moving Wright ma- chine, and who taught her brother, the famous Eddie” Stinson, to fly, designs houses in Santa Fe, New Mexico. Harry N. Jones runs a radio and electrical (Continued on page 162)

MONEY MAKING OPPORTUNITIES SECTION 161

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ener earned enough in 18 months to pay THE FATE-ROOT-HEATH CO. it uadhny 933-956 Bell St., Plymouth, Ohio, U.S.A. ! Send me the book that tells me how I can make my 4 spare time worth $4 to $6 per hour. ‘ é : NR. + dc 0 0: 90004480 6 anepeechebatens de dnuwanenene j bd I «ac 90 d:5:9'0 gawd ap Sse NEMA. «pce i how others do r£,/ kak drink: Btaicinve kia 5 »:nen:0 40:0 nm ae

nee couRsE for *2 Haven’t you often wished that you could draw cartoons, illustrate some idea, sketch some pretty face, etc? You can do all of these things. One of America’s most famous Cartoonists and Illus- trators has developed a great. simple system for in br hes of Commercia: Art. This system has revolutionized the entire theory of drawing. It means that drawing can as easy for you as writing—much simpler than A Real Opportunity is offered able, experienced men who are ambitious—Men who can sell, or- ganize and direct crews of go-getters in every principal trade city. These men

will have good references, know they. reruiis chonahanll Gestion ex tates can make good, and prove their earnest- writing. We are now placing this original system for learni ra d wing, rt an Cartooning, consisting of 34 lessons with over 500 illustrations, within reach of every one. If you will devote a few hours each week to the Course BSO- LUTELY GUARANTEE that you will learn to draw and draw well before you have half finished the Course. If we fail to make this claim good, we will refund every cent paid us. By eliminating a large office force for answering corre- spondence, expensive catalogs, etc., we are enabled to make a price of $2.98, the cheapest price ever known for a high-grade, home study course. Many have sent us letters similar to that of Rob’t P. Davis of Detroit, who wrote: “I can’t see how you ask so little, when others with inferior Courses get from $20 to for theirs. It is more than I expected.” Learn to draw. It is a big asset, no matter what field you are in. ness by making a small initial investment in a product of a sound and highly rated corpora- tion. Product retails at $15.00, a repeater, na- tionally advertised, with a proved market and 24 million prospects in U. S. A. Extensive experience has proved it invaluable as a labor- saving device, in offices, banks, stores, factories and homes. a Territorial rights will be granted men of managerial calibre who can qualify. It will be a red letter day in their lives. Unusual op- portunity is also offered to salesmen to qualify for positions which will pay handsome returns for honest effort, and offers permanence and

growth in power and income. Send No Mone Replies should give full details of personal Saat ni Oe and $9 A It zou order | the Course business history. All letters will be answered. on arrival pay. postman ° drawing k outait, Sonsisting Address G. S. M.,’Dept. 2 fa full Tor the ‘qptire “Coures sad » eraners, , cams ress G. 5. °. lept. be no iy o9 ing you 173 W. Madison S¢., Chicago Feri REFURB "MOWED" 22 | Sieatece . 9

LEDERER SCHOOL OF DRAWING, Dept. 662-P, Chettancoga,T 5 Orders from outside the U.S.A. are payable $3.28 cash with order. s TRAVEL FOR “UNCLE SAM” RAILWAY $158 to $225 Month POSTAL CLERKS MAIL COUPON BEFORE YOU LOSE IT # FRANKLIN INSTITUTE, Dept. P273 ROC R.

’ N. Y. e b, Wte: Ba @ Sirs: Rush to me without charge (1) 7 # book describing positions as Railway Postal Clerk # and City Mail Carrier; (2) tell me how to get a # U.S. Government job; (3) send me list of posi- tions now obtainable. See Your Country Many other Government Jobs obtainable. MEN—BOYS; 18 UP ff DN b.a5csh5'ss sd anaes seee tele eee a Address. . ee eo

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a It provides a quiet luxu in an outboard ride. heard while driving at full speed. with gas! lutionary improvements that distin Johnson Sea-Horses from all o motors. i 2583 Pershing Road, Wauk: | In Canada: Canadian Johnson Motor Co., SFA-HORSE. The Johnson Underwater Exhaust eliminates ex- haust reports and gases from outboard motoring. ‘a you’ ve neverexperienced ow you can talk and be The Johnson Release Charger adds a hundredfold : to outboard motoring enjoyment by insuring easy starting... positive starting...under all conditions --.even when the motor is stone cold or flooded Write for catalog describing these and other revo- ish the new er outboard Six models, priced from $115 to $325, F.O. B. Wau- kegan. Sold on free trial and easy payment plan. JOHNSON MOTOR COMPANY POPULAR Sea-Horse Four Cylinders , Peterborough, Ontario Distributors for British Columbia, Hoffar’s Ltd., Vancouver, B. C, | Johnson Outboard «Motors WORLD’S LARGEST MANUFACTURER OF OUTBOARD MOTORS ee ee ee a et et et tt SCIENCE MONTHLY LCL, A REMARKABLE CAMERA ACCOMPANYING THE BYRD ANTARCTIC EXPEDITION 36 Pictures in One Load Perfect Enlargements to 12”"x 18". Screen Projection LEICA —The Precision Camera UNDREAMED-OF photographic ven- tures are possible for the LEICA owner. Extreme flexibility with mechan- ical and optical precision give the LEICA a variety of abilities possessed by no other camera to the same degree. Scenic pictures, portraits, interiors, suc- cessive panoramic pictures and photo- micrographs are within the scope of the LEICA A highly corrected F3.5 anastigmatic lens and focal plane shutter adapt the LEICA to all light conditions. Speed of 1/20 to 1/500 second. Enlargements to 12x18 inches are the equal of fine contact rints. Fits in vest pocket or lady’s a Re ready for instant use. Thirty-six exposures from one loading of cinema film. Positive film from negatives for screen projection. Demonstrated by leading photo supply dealers or send for details and examples of the work of this wonderful camera. E. LEITZ, Inc. 60 E. 10th Street New York E. LEITZ, Inc., 60 E. 10th St., New York Please send Pamphlet 1127-P.S. on LEICA Camera. SSPPERERREAERBRERRESBEALLSSSSESO HCO ETE ED seeepeseseeseaeeees eee eee eee tcee ese eeeeseeeeeesceeeesueseeeeeeeseseeeeeeseaes Tee eee eee eT Tee eee ee ee eee eee ee AIR=CON UTILITOOL THE KING OF THEM ALL Versatility Plus Not only a complete work-shop, but a sturdy, powerful, precision-built work- shop, is the Ar-Con Utilitool. The heavy, reinforced cast-iron-bed lathe is 31 in. between centers, and is powered by a % H.P., ball-bearing motor of the super-efficient repulsion-induction type. Comes with grinding and buffing wheels and full lathe equipment, including wood- turning tools. Lathe also serves as foundation unit and motor drive for circular-saw table, jig and scroll saw, and sanding disc and table— all of equally efficient design and sturdy, accurate construction. You can buy the complete outfit, or any of the units separately, on very easy terms. To obtain complete information merely write your name and address in margin, tear out and mail to THE AR-CON TOOL COMPANY 500 Fassett Street — Toledo, Ohio May, 199 ae Back of the Month’s News (Continued from page 161) store in Portland, Maine. Frank T head pilot of the Wright School in its pal 1911 days, sells real estate in Hollywood, if as do two other early airmen, Earle T- Ovins. un oF psa 7 Bleriot flyer, and C ml . Willard, one of the origi i =: tion pilots. ginal Curtiss ex Two others who “barnstormed” Curtiss flyers in the early days are Witmer and Augustus Post. © Witmer Taises chickens in California and Post is writing and lecturing on aviation. The Fiddle-Maker’s Secret REPORTS from Rome telling of the te. covery of papers written by Antonio Stradivari, who died in 1728, set the world of musicians on edge in anticipation of the reye. | lation of the secret of Stradivari’s varnish, For the violins made by Stradivari and his sons, to whom he imparted the secrets of his art, are the finest ever made. To possess one ig the ambition of every fiddler; to own one re. quires the investment of from $25,000 ‘to $100,000, so highly are these instruments prized for their musical tone alone. If the secret of the varnish which Stradivari used could be discovered, violin-makers be. lieve, new instruments equaling these old mas. terpieces in tone could be made today. Their great age alone does not make these instr. ments so precious. Nicolas Amati, Stradivari’s predecessor and teacher, made fine violj some of which are still in use, but the best of them, though older, do not equal the “ strads,” Violins made by Guarnerius and other con- temporaries of Stradivari have been eq by those of modern makers. The Strads stand alone. According to Milan authorities, the formula for the Stradivari varnish was actually found among the old papers, and has been tried by an instrument maker of that city. Experts are skeptical, however, awaiting an actual demon- stration. Every conceivable test has been ap- plied to the varnish of genuine Strads, in the effort to analyze it and reproduce it, but with- out success. That the method of applying it has as much to do with its tone-producing quality as its composition is probable. Stradi- vari is known to have apologized for the delay in delivering a violin by saying that the time required for his varnish to dry made it im- possible for the job to be finished sooner. All varnish is made from resin of one sort or another, dissolved in oil, alcohol, or t tine. Fossil resins such as amber, which is mined along the shores of the Baltic, where it was deposited by great forests of trees which grew before the last Ice Age, 1,250,000 years ago, and copal, similarly mined in Zanzibar, make the highest grade of varnish. Kauri gum from New Zealand is valuable for high-grade varnish, while most of the commercial var- nishes are made from the resin of the southern pine. Probably Stradivari used either amber or copal, mixed with some pigment to produce the orange-red color of his violins. It is known that each coat of varnish applied to any of his violins was rubbed with the bare hands of men and women day after day while it was hard- ening. An earlier violin-maker of Crémona m a letter to Galileo said that his instruments could not be brought to perfection without the strong heat of the sun, so it may be ima, that each Strad had its long series of sun baths before it was delivered. a No violin made since 1740, when Stradivari s sons retired from business and locked up their secrets, has been able to produce the tones which a genuine Strad sings. Nor will any until the secret of the old maestro’s varnish 8 rediscovered. with the © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. with 1D ference men. require fully s¢ Ther mobile pliance variet) 14-in. | uses al ore ‘ ane rough The 8 wrenc carryi tappe wrenc Spark satisf: Th autho lent: USS and ‘ Sp awkv varie for y wren cranl

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May, 1929 —— Tools to Keep Your Auto in Repair By Ray F. Kuns ‘ncipal, Automotive Trades School i Cincinnati, Ohio take pride in keeping their cars in repair. Others attempt to do it with indifferent success. Often the dif- ference lies in the tools rather than the en. Repair and servicing operations wire the use of good hand tools, care- fully selected. There are many places on every auto- mobile where special wrenches and ap- liances make the hard task easy. A variety of wrenches is needed. A 12- or | 14-in. pipe wrench in the kit serves many | yses about the automobile as well as for | plumbing repairs. Another general pur- | pose tool is the monkey wrench. A 14-in. | monkey wrench will handle much of the rough work on large nuts about the car. The 8- and 10-in. sizes of adjustable end wrenches are especially desirable for carrying in the tool kit of the car. For tappet adjustments, a set of special end wrenches will make the work easier. Spark plugs also may be handled most satisfactorily with a special wrench. Mi“ home workshop enthusiasts m author are the following or their equiva- lent: Nos. 21, 23, 25, 27, and 29 to fit USS. nuts, and Nos. 721, 723, 725, 727, and 729 in the S.A.E. nut sizes. | Special wrenches of odd shapes for | | awkward places are available in a large | variety; be sure to get the ones designed | for your own car. ‘The T-handled socket wrench is excellent for speedily removing crank case pans, and running nuts on and | off when adjusting rod or main bearings. | It is always safe to purchase speed wrenches in the >- and 3-in. S.A.E. sizes. A breast or electric drill, a hand drill, and a bit brace are of use in auto repair work as well as in making furniture or household repairs. The drill bits for the breast and hand drill should be in an assortment of sizes up to 3¢ in. ree bearing scraper is a necessity for A bearing work and a valve spring lift- ing tool should be selected for your own particular car. Measuring and marking tools for auto- mobile work include a try-square, a steel rule, and calipers. In addition there should be a thickness gage for testing the clear- ness of valve stems, pistons, and similar parts. _Ball peen hammers in the 1- and 2-lb. sizes are desirable. Chisels, punches, and screw drivers of varying sizes are included in the well-stocked kit. The soldering iron is often used for electrical repairs, but it also is called into service for repair work on the gas tank, fuel tubes, and radiator. In connection with its use a gasoline torch is handy; it serves to heat the iron and, when neces- sary, the work. Tin snips, hack saw, files, and similar tools find a multitude of uses, both about the automobile and in other home workshop jobs. The end wrenches preferred by the | POPULAR SCIENCE MONTHLY 163 af ee he ite ae re 3 3 te A t o> —_— a . ERV ICE “og cars S ing © Owners of the aa n Mo dvan' To Flint io —_ Speci 6 Frank! d : Oaklan@. Pak Master Six G32 1926 Gartim Bros. Trucks Reerles Knight Buick Stam 6 Henney, . — 1926, to A 27-28 Cadillac, 19 Hupmobile debaker. 1926 Chrysiet Jordan r DeSoto : sel Stey Dew Kinchestet ve at Cab Buesenbers es rtridged Whe sa Elcat 1927-28 _ to be oe Ere ruc our cat; needs thereafter t once, to ‘| filter of Y™'g.900 mile ur cats & * C/ Jator, the OF "ud every 8. elf, take YOUF Wie Purolato e The Purot '8,000 miles * OUTS | e-cartnidse Feng - j 7 do this = eck them to of the heavy 4 have driven an . in © . tt beginnt S UROLATOR, the Oil Filter on your motor car, assures you, at all times, a _ plentiful supply of filtered, clean lubricating oil. Purolator removes from the oil and 4o/ds all of the harmful dust, dirt, metal particles and hard carbon which, if allowed to circulate through the lubri- cating system, would cause costly damage to cylinder walls and pistons, bearings and gears. After 8,000 miles of average driving, however, Ach Vout the Purolator cartridge contains too much pe foreign matter to be sure of continued efficient weal operation. Then, to continue to protect your motor—and your pocketbook—this cartridge must be removed and replaced by a new, clean one. Just re-cartridge your Purolator every 8,000 miles (or ask your garage or service station to do it for you) and you need never worry about the damaging effects of dirty oil. Ah Most of the leading manufacturers equip their fi cars, at the factory, with Purolator Oil Filters— at for the protection of the owners of their cars. Their engineers have selected Purolator because Purolator is produced by the criginator of and f-~ leading authority in motor car oil filtration. IN \ 4164 Motor Improvements, Inc., 352 FRELING- ae tm Fede (fee HUYSEN AvENUE, Newark, N. J. e RY pf ® Licensed under Sweetland Patents PUROLATOR THE OIL FILTER ON YOUR MOTOR CAR

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| | amen a ee 164 POPULAR SCIENCE MONTHLY TME SIMPEEFIED | GRAFELEX sangatencoae bars , oo . ; For real Childhood Pictures—there’s |... ||. no other camera like the Graflex. 1 never know at what in- stant you'll have a chance at a picture that will be precious to you for life. The one camera in which you can watch” | each nroment’s fleeting expression exactly as your. negative will “see” it, is the Graflex. y ry 7 And now there’s a simplified Graflex, the camera that removes all guesswork in focusing — ready in an instant for the ordinary picture i or for a thousandth of a second speed — priced within everybody’s ‘reach. 3%” x 4%" Graflex, $80. .... Other models $85 to $375. ’ FEATURED BY THE BEST DEALER EVERY WHERE LEX Sim PLy PERE —J ROCHESTER, NEW YORK May, 1999 | soon. When you stepped on the Starter last | the carburetor that told me the intake yalye | little charge got in was pushed right out again | pressed.” | any attention to it.” When Valves Geal Out of Step (Continued from page 84) revolution. The rest of the time it pushing out the burned gas, pulling in g charge, and ramming it into a small s ne it'll explode with plenty of pep when the spark occurs. “Then,” Van Tine observed, “if that’s the case I can see why the valves have to and close at the right time. If they didn’t the piston couldn't do those stunts.” “Exactly,” said Gus. ‘‘ When the piston starts down on the intake stroke, the intake valve must be open to let the gas rush in, snd night I could hear a funny hissing noise didn't open until the piston was quite a down in the cylinder and stayed open long after the piston started up again, so that what through the carburetor instead of being com. “Now that you mention it,” admitted Vag Tine, “I noticed that funny noise, only | couldn't make out what it was, so I didn’t pay. “*Next time you'll know better,” said Gus, ““When a motor makes queer noises it’s always’ trying to tell you something is wrong. The chances are it isn’t important, but it always pays to investigate anyhow. i “(TP IMING a _ motor,” Gus _ continued, “would be a tough job if you had to time the vaives one at a time. But becauseall the valves are worked by the cams mounted on a single shaft, you don’t have to do it that way, If you get either the exhaust or the in valve for any cylinder timed right, then all the rest of the valves in the engine are bound to be in time.” **Sounds logical,’’ Van Tine agreed. “Now how do you find out how to time one of the | valves?” ““Any good auto mechanic can time the valves so the engine will run pretty well, but’ you can't do an absolutely accurate job unless you know the auto maker's specifications for timing or unless the flywheel is marked with timing lines.” *‘Aren't all gasoline motors timed alike?” Van Tine asked. ‘‘ What's the flywheel got to do with it?” “They're not alike,” replied Gus, “because! the valve timing depends on a lot of things, such as the diameter of the valves, the shape of the cams on the cam shaft, and how high they lift the valves. In some motors, for in- stance, the exhaust valve closes just as the piston reaches the top. In others the exhaust valve doesn't close till the crank shaft has gone past top position as much as thirty-two de grees. This happens to be one of the top dead center cars and there’s a line cut on the fiy- wheel which tells, when you get it in line with the pointer, that the piston is on top deat center. So all we have to do to time this cars to turn the crank till the marks line with each other, find out which piston happens to be at: the top, and set the cam shaft so the exhaust valve for that cylinder is just closed, and the, job is done.” “oe do you find out if the piston is at top center?” h “Easiest way I know, "replied Gus, “is to take out a spark plug and shove a piece of wire into the cylinder so you can feel when the pis ton gets to the top.” ‘ “Tf I'd done that and checked up the pos tion of the valves when I had one of those spark plugs out last night, I could have located the trouble right away, couldn’t I?”’ sug; Van Tine. “Put that down in your notebook so you won't forget it!’’ Gus smiled. ———$— n= pe WF, If

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a8 F- Rice ae 1929 POPULAR SCIENCE MONTHLY 165 y Headlights and Bumpers are CHROMIUM PLATED.

HROMIOUM plating is a process much like nickel apres It consists of depositing on an article a covering of chromium — The plater is responsible for the strength of his solution so ar as chemical formula and load is concerned. The process is essen- tially electro-chemical. Three factors are closely related in the suc- cessful operation of chromium plating operations—1. The composi- tion of the Chromium Bath—2. The current density or the proper amperage for the load and—3. The proper automatic control of the temperature of the solution. Variance of either current applied or temperature greatly affects the finished product. Temperature Control is MOST IMPORTANT in the successful application of Chromium Plate— Fycos Automatic Temperature Control insures a maintained quality of Sniched product. It is positive protection against spoilage. Without it Chromium plating would be a process involving great risk of spoilage.

‘ In every kind of industry, Zyeos Temperature In every indust Control instruments are guarding against spoilage—delivering continuous quality of pro- duct and in many instances they are the basis of various heat treating processes. Taylor /nstrument Companies Main Office and Factory ROCHESTER,N.Y. + «+ U.S.A. Canadian Plant: Sees BUILDING, TORONTO SHORT & MASON, Ltd., Manufacturing Distributors in Great Britain Write for literature on fos instruments for temperature control

“SIXTH ~ SENSE ~ OF .~ INDUSTRY E COS s Temp erature Instruments a0

DICATING * perature CONTROLLING male LD A BB ahs

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POPULAR SCIENCE MONTHLY May —_ Here Are Correct Answers t Questions on Page 45 1. There is no difference what betwee so-called “static’’ electricity and the - forms of electrical energy. All forms rns trical energy are manifestations caused by ¢ disturbance in the make-up of matter by a according to the latest theories, is composed of | positive protons and negative electrons. i 2. If a current of electricity amountine: one half an ampere is forced thew the hal body, the result will be death. The vols: required to force this amount of eyema through the body depends on the resistange# electric current encounters in getting into out of the body. That is why the shock you get when you touch, with the end of yon! finger, the “‘live’’ contact in a 110-volt lig socket is not fatal. You can get a seven) shock from a 45-volt B-battery if your ha are wet and you grasp large metal electrodes connected to the battery terminals. Pegpis| have been killed by 110-volt light curren If, for instance, you are standing in a bath full of water and you turn the light switch may be killed if the switch is defective, 3. Air in its normal state is a nonconduch of electricity, but if you apply enough yolty or pressure, the air becomes ionized and that state it is a relatively good conducts 4. Ordinary electric light bulbs pop whe they are broken because practically all the air has been pumped out of the bulb and when the glass no longer supports the outside pre the air rushes into the vacant space so violeni as to create the noise. The larger sizes of bi of the nitrogen filled type do not make mu of a pop because the gas pressure inside i much less than outside. Give Old Floors This Beauty Treatment KYANIZE Floor Enamel 5. According to the latest theories air every other known substance is m . protons, which are positive particles of tricity, and electrons which are negative ps ticles. Since all substances are made of 1 ing but electricity, there can be no air witho electricity. However, in normal air, the eles trical charges of which it is composed are! a state of balance, so no outward electri manifestations are apparent except ~ produced by weather conditions. 4 6. The function of the insulation’ "te electric wire is to keep the wire from toueli any other conductor of electricity. If wires in your home were so strung that it wo be impossible to touch them with your hai and so fixed that they could not sag agail each other or touch anything, there wo no need of any insulation. _ hard work or heavy expense. will add beauty, charm and value to your floors and woodwork and you can use the floor in six hours! FLOOR ENAMEL is the all-around floor coating. It is equally effective indoors and out, on stone, cement, concrete, wood or old pattern-worn linoleum. No matter how badly worn, scratched, scarred or stained an old floor happens to be, you can transform it into a new, perma- nently bright, spotless area—proof against water, weather, wear—even the corroding effects of acid. Eleven solid colors enable you not only to finish old floors but to decorate them as well in varying patterns. Excellent, too, for porch, lawn and garden furniture; farm wagons, gear and implements. 7. Since nobody knows what electricity 4 tually is, it is impossible to define the distin tion between positive and negative electricity All we know with any certainty is that seem to be two kinds of electric charge. T electronic theory of positive protons rounded by rapidly whirling negative electi seems to fit in with more of the observed f about electricity than any other theory vanced up to the present time. Send for our new booklet, “The Charm of Painted Things,” or if your dealer cannot supply you with Kyanize, send $1.00 for a special trial can with brush and booklet included. __, 8. Pure silver is the best conductor + Special $1.00 Offer If your dealer does not carry Kyanize Floor Enamel (solid covering) send us his name and ONE DOLLAR and we will forward to you postpaid a trial can of this master enamel for old floors including brush to apply it. Men- tion color you desire—Dust Drab, Light Yel- low, Warm Gray, Navy Gray, Dark Yellow, Rich Red, Tile Green, Golden Brown, Ma- hogany Red, Buff, Deep Orange. BOSTON VARNISH COMPANY 263 Everett Station Boston, Mass, U.S.A. electricity. Pure copper runs it a close second All metals are relatively much better conduct tors than nonmetallic elements. Size for siat aluminum wire is not as good a conductor copper or silver, but if you compare the @ ductivity of a piece of silver or copper Wi with the conductivity of a piece of aluminul wire of the same weight and length, you find that the aluminum wire is the bet conductor. This is because it is so much lightet than copper or silver that a much larger ean be used.