Popular Science Monthly 1929-02: Vol 114 Iss 2

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nds out fo ation Of e, fi aple act throat seriou its sys agai nst, e kills ) phoi 0 econds ffective ich ; ju may in an otic in it wo ure t@ Nava (lets opular February CICENCE 25 20::: MONTHLY Founded 1872 “JAN2 1929 PRERIGDICAL PoOM GENERAL LIBRARY UNIV. OF Mice. Aviation ~Radio ~Automobiles “Home Engineering “Exploration «® The HomeWorkshop *e ~

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A single= track mind EVEREADY BATTERIES do one thing. And do that well. They pro- duce electrical energy—long-last- ing, hard-hittmg electricity ready to transform itself into brilliant light or driving power at the turn of the switch. ALL Eveready Bat- teries last longer — because they are made to regenerate fresh power when not in use. Remem- ber the name—Eveready. Ask for it. Get it! Eveready Dry Batteries have a single-track mind. Their one idea of success in life is to produce hotter sparks and more of them. When Eveready Dry Batteries are not working they restore their energy—that’s why these batteries ast so long. Use the Eveready No. 6 dry cell in the house for bells, buzzers, electrical experiments and motors. The Eveready Hot Shot in its water-proof steel case laughs at rain and weather. When your flashlight goes dim -—shove a charge of Eveready con- centrated daylight down the tube! Eveready Flashlight Batteries will flood dark places with dazzling re- vealing light—cost only 10 cents each at stores everywhere. NATIONAL CARBON CO.. INC. New York (|! ' San Francisco Unit of Union Carbide and Carbon Corporation @ ©

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February, 1929 POPULAR SCIENCE MONTHLY What does it matter ... if you are not the first owner of your CADILLAC: LASALLE They Are Built to Last a Life-time And Never Lose Their ANY who have longed for a Cadillac, are today find- ing that wish fulfilled in a Cad- illac, or in a Cadillac-built La Salle, that has passed from the hands of its first owner. Such purchases represent the exercise of common sense judg- ment, because Cadillac and La Salle cars are built to last a life- time—with just reasonable care. No other cars offer the same advantages of long-life per- formance, because no others are powered with the famous Cadillac-La Salle 90-degree, V-type, 8-cylinder motor — by long odds the simplest and most dependable of all types of Eights. General Motors engi- neers, laboratories and test- ing grounds, as well as hun- dreds of thousands of Cadillacs and La Salles in owners’ hands, have completely demonstrated this to be true. Purchasers thus realize that it does not matter at all if they do not happen to be the first owner, for they know that Cadillac and La Salle cars never lose that identity which distin- guishes them from all other fine cars. Back of this confidence in Cad- illac and La Salle is the com- plete assurance of absolutely fair dealing, no matter what make of used car may be selected, because Cadillac-La Salle dealers also exercise com- mon sense business judgment. Identity They know good will is their greatest asset. They want the buyer satisfied, because they want him to return—perhaps, eventually, to buy a new car. They know good will inspires many customers to recommend the Cadillac-La Salle dealer to their friends who want good used cars. Because the Cadillac-La Salle dealer occupies an advan- tageous position his used car stock is large, varied and well- conditioned. These cars are reasonably priced because no _ Cadillac-La Salle dealer is forced to take trade-ins at fictitious values. It’s well worth your while to investigate these statements. CADILLAC MOTOR CAR COMPANY Division of General Motors Corporation Detroit, Michigan Dealers Conveniently Located Oshawa, Canada

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SS ams c-—— ——— lyr AI A POPULAR SCIENCE MONTHLY February, igy —_ —_—_—=:!_ WHAT IS NEW THIS MONTH | Table of Contents for February LEADING ARTICLES Coat From CABBAGES . . . By Grover C. Mueller How the synthetic chemist’s new magic affects your daily life BurILpInc THE GREATEST BRIDGE. . . By Edwin Ketchum Marvels of a colossal structure to span the Hudson River Snurrine Our a Grant CANDLE... . By John E. Lodge How daring men fought and won a thrilling battle with a nf tte oil well WASHINGTON AND LincoLn Botu Were Inventors By Homer Croy Little-known triumphs of two of America’s great men New Proors Tuat ANIM™ALS REALLY Can Tunk By Robert E. Martin Amazing feats of dumb creatures’ intelligence PRrosPECTING FoR GOLD BY ELECTRICITY By George Lee Dowd, Jr. Finding buried treasure with a pair of headphones Liquertep HELIUM Bots on Ice anp “Freezes” Tix By Arthur A. Stuart Strange new uses for America’s fireproof airship gas A New Guipe To THE Heavens... ‘ Where astronomers have found thousands of new universes SOS!—A CHALLENGE TO SCIENCE . By Frederick Tisdale What inventors are doing to avert sea disasters Ir You Hap Mi1ui0ns To SpenD— . . By Michel Mok An unusual interview with Harry Guggenheim, godfather of ~— R«nGsiDE SEATS ON THE OcEAN Bottom. i Taking movies of sharks and suckers from a “hole in the sea” Tue Rear Fatruers or Fuicurt . ‘ By John R. McMahon Continuing the intimate story of Orville and Wilbur Wright Tives Make THE Eartnu Bor. Over. By Edwin W. Teale How new facts are solving the mystery of why volcanos erupt Now You Can Eat SunsHINE By Frank Parker Stockbridge Newest uses of invisible ultra-violet light Sxy Rartway Runs To StrancE Hore. An engineering wonder of the Alps New Marvets or Puane Desicn Why airplanes can’t be built like automobiles WaEN THE Sky Rats Sotpiers!_. Remarkable experiments in fighting battles with parachutes SPECIAL FEATURES Cover Desian. . P By Herbert Paus Imposine A SAVING SENTENCE ON a SPENDTHRIFT By Wallace Ames How to keep money after earning it Hep ror Youn Burpine . Announcing a valuable new service of Popular Science Institute Our Reapers Say— . Way Two Sets May Loox AuKE, put BEHAVE DIFFERENTLY — By John Carr By Alfred P. Lane . By Robert T. Pound What goes on inside a radio receiver Rewrrine ror A.C. Smpiiriep ir. Short-cuts for the amateur builder of sets DecoraTivE Meta Sawinec . . By Edwin Thatcher What you can do with a jeweler’ s blade | Pinc-Pone Tasie Foups nto ScREEN . By Charles A. King An unobtrusive outfit for a newly popular game ConTROLLING A Mover Rartway . By Frederick D. Ryder, Jr. Tricks in running miniature trains Turninc Rines or Woop. . . By Herman Hjorth A master craftsman tells how to make rounded pieces Luxuries To App To THE Home. . . . By Milton G. Sturgiss A glimpse at the new comforts of the 1929 model Eprroriais . . ‘ . Waar Feeps Gas to Your Car? Gus and Joe discuss fuel supply systems "By Martin Bunn 12 14 64 76 77 78 79 80 82 a4 Astronomy Screen Production Shows Motion of Planet New Comet Discovered by an Ama- teur . ; Oceans on Frozen Planet May Be Liquid Air ms ee ee Automobiles Steam-Puffing Granddaddy of Mod- ern Auto Found. Know Your Car . Invents New Front-Wheel Drive for Autos. Tractor Sets 1, ,830-Mile Endurance Record . Swinging Auto Crib Rocks the Baby toSleep ._. One Time in Five It’s the Train That IsHit . Closed Car Has Removable Top to Admit Sunshine. . “Auto Wheel Minus a Hub” Design- ed to Save Weight . Inflates Soft Tire with Air from the “Spare” . Oregon Village Sees Its First Auto- mobile. : Every Little Dial Has a Meaning Women Drivers Can Signal Now— No Excuse ‘ Removing Radiator Obstructions A Tool Compartment Lock . Both Doors Open at Once. When the Battery Is Dead . Blowing Starts Siphon Ten Dollars for an Idea . Aviation Finless Safety Monoplane Flies with Hands Off Invents Gyroscope to Balance Planes Convertible Balloon-Dirigible Test Three-Bladed Propeller. Odd All-Metal Dirigible Ready to Fly. . Climb han Miles to Take Air Pic- tures . Huge Searchlight Batteries for East- ern Ai ‘ “Ghost” AR Nearing Comple- tion . ‘ More Records Smashed . A Great Seaplane Harbor Silencing Roar of Planes . First to Fly in Antarctic . Planes Wear Life Buoys . New Gun Sprays Bullets . , New Material for Airship Bags. . cot Explorers Find a New ugar Nearly Plan Ww orld’s Largest Airplane Plant zs Air Landmarks Should Be Yellow, White, Black ST ee Februar second-class _perinens Canada. Printed ‘in U. 8. A. Copyright, 1929, oy Se Popular 1929, Vol. 114, No. 2. Pogutes Getence Monthly is published month- at 2. Fourth Avenue, New York, N. Y., by the het Science Publishing second-class matter Dec. 28, 1918, at the Post Office at Science Publishing Co., Inc. Single copy, 25 cents. Yearly subscriptions to contents of thi sci Popu of the vidual Monthly articles for stock. President and Treasurer; R. C. nited States, its possessions, and Canada, $2.50; fo S$ magazine must not be reprinted witho senting in its editorial columns numerous stories of new products of ap lar Science wt does not: underwrite the business methods 8 or concerns producing them. The use of yooules Science permission. In countries, $3. whe ied 7 is never authorized. pp. Capen, ilson, V ce Presidents A. L: Cole Becsetary i. a

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bruary, 199 62 70 75 j February, 1929 POPULAR SCIENCE MONTHLY — “Beams” of Sound to Guide Air- craft in Fog . Bird’s-Eye View from Plane Reveals Buried City . Pera hare Fights Fire inthe Air. . “Prop’’ Blades Made Hollow Hops from Train—Crash! “Aerial Fish Express”’. Duration Record Stands . Engineering Five-Mile Highway Built Across James River. . Bolstering Up the Leaning Tower of Pisa . Suspended by Crane, House Rides Across River. . ‘ World’s Greatest Gas Line Exceptional People This Dentist Had Courage ; He Built His Own Castle—on the Ground . He Made American Flag of 33, 000 Wheat Kernels... Paints First Scientific Portrait of Spectrum. Health and Hygiene New Cancer Hope. . Weak Feet Walk on Air in New Arch Support. Life Span 100 Years by 1950? Ex- perts Differ . Masks Safeguard ‘Health of Paint Spray Users. . Compressed Air Drill New Aid to Surgeons. Grafts Part of Human Eye i in Amaz- ing Operation . Tests Show Canary Bird Is Best Gas Detector. . Doctor Makes 7,000-Mile Call by Radio. . Colds Blamed on Lack of Proteins in Diet ‘ Laboratory Deamaiee An Artificial Heart! —o Thunderbolts from a Glass Invisible Forces Photographed! . , “Lightning” in Auto Motor. . . New Experiment Confirms ae of Einstein . Models was Movie Thrills with Tiny Toy Trafe Problems Revealed by Work- ing Models . . Building the Buckeye State . Whittling Model Propellers . Nature “Busy Bee” a Myth—He’s a Loafer, Tests Show . . Rocky Mountain Wilds Are Pre- served for Science . . . English Hard for Parrots. . Big Trees, Centuries Old, Found to Be Fireproof. . Tin om Plants Build Houses of ealth Glass. . . Landmarks Guide Pigeons Home? . New Sugar Discovered in Dahlia Juice . ; Lizard Hypnotized! , If Brain Size Counted, the Whale Would Be Smart. A New Kind of Mosquito! This Makes 141 ‘ ‘ From Mountains of Mystery, Killed by Too Much Light . 62 73 132 . 132 . 132 . 132 . 132 59 63 69 75 37 68 70 71 50 56 58 59 61 63 73 74 51 51 68 69 SSS 56 58 59 71 71 74 75 75 75 . 150 : 150 4 New Devices for the Home New Electric Broiler. . 38 Straight-Edge Ladle Gets Food Out 38 Handy “Automatic Pincushion’”’ 38 Extracts the Last Drop of —_ Juice. . 88 Gas Refrigerator and Range i inOne. 38 Pie Pan Has a Handle . 38 Waffle-Iron with Built-In Thermom- eter . — . 388 Novel Frying Fork . 38 Egg-Timing Alarm C lock. . . 39 Springs Operate Odd Kitchen Churn 39 Wall Hook Snags the Clothesline 39 Newest Holder for Steel Wool . 39 Keeps the Percolator Top from Fall- ing Out . 39 Combination Toaster and Percolator 39 Nonspill Salt-and-Pepper Shaker 39 Makes Either Coffee or Tea. . 39 Electric Sandwich Toaster . 39 Built-In Medicine Cabinet Has Ad- justable Mirror . : 39 New Processes and Inventions Drives Rocket Motorcycle 37 Detects Artificial Pearls .. 50 Swimming Turtle Is Hour Hand of Novel Clock. . 56 Air Propeller Drives Novel Cata- maran 56 Soldering Jobs Simplified by Electric Furnace . 57 Traveling Shears Clear Phone Lines of Litter. . 60 Self-Dumping Scow Turns Somer- sault inthe Water. . 61 New Hand Truck Picks Up Piles of Boxes. . 62 Principle of Range Finder Applied to Depth Gage. . 62 Fabricated Lumber Cut in Labor- Saving Shapes . 68 Amazing Machines Do Work of an Office Force. . 69 “Fountain Pen” Pistol Can Shoot Deadly Bullets . a Would Foil Bank Robbers . 70 A Mechanical Substitute for Tailor’s Shears. 70 Folding Pusheart Runs on Rubber- Tired : 70 Three-Wheeled Motorcycle Runs on Endless Tread 71 Novel Card Table Serves Also as ' Movie Screen 71 Dry Cell Blasting Device Resembles Flashlight 71 Tin Can Filling Station for Ciga- rette Lighters .. . 74 Tiny Dynamo Operates "New Bat- teryless Flashlight . : 74 Holder for Pipe Cleaners. . 75 Novel Lamp Cord Holds $ Cigarette Lighter . . 75 Radio Radio Pictures Made Lifelike 58 A Useful Transformer Test _. 67 When Batteries Play Out 67 A B C’s of Radio . 67 Handy Radio Aerial Mast Clamps to the Roof... 69 Stations Identified I by This Radio es ss 74 Unusual Facts and Ideas One Jump Ahead of Death! . 36 Modern Cave City. 37 Light Organ Paints Scenery . 37 s Necklace 35,000 Years Old . 50 % “What Can I Make from a Block?” . 1 @ Each Color Has Its Number Farms in the Sahara? Will the Ocean Overflow? The Tropics in a Box. . No Fire in Redheads? . Every Man His Own Still. Cathedral Blasted from Cliffs . . Human Body’s oe Reported Photographed . Opals, Once Feared, Today Yield Vast Fortunes Latest Ice Cream Cone Wears a Bonnet . Searchlight on Wheels Aids Fire Fighters . Cameraman Snaps Torpedo ‘Diving into Waves. . Gypsum Increases Soil’s C. apacity for Moisture. . Tribesmen Jail Idols if Prayers ‘Are Unanswered. . Begin Search for Diamond Fields in Canada . Your Busy Heart Is Fed by Tiny ‘Dinner Pails” . Rubber Band Returns Ball in One- Man Tennis. . Chemical Makes Open-Air Ice Skat- ing July Sport .. Catch Birds in Fish Nets Where Half of the World’s Gold Is Weighed. . Speeding Typists’ Fingers with Radio 50 50 51 51 52 56 57 57 58 58 58 58 59 59 61 61 “Jazz” . 62 Walls Hide Radiators in Novel Heat- ing System . 63 Stunning Gowns of Metal Soon May Be the Style. . 68 Put Milk in the Dark to Keep It Fresh. . 69 Urge Metal Storage for War Needs. 69 Nobility Not Degenerate, Genealo- gists Assert . . Pare, Europe May Soon “Eat” Its “Drinks” in Solid Form . . .. °70 Gives American “‘Talkies” Foreign Tongue . 70 Find Rare Handwork of Cave Men Jewelers. . : 71 Road Signs Teach Geology ; 72 Holland Tunnel Handles 8,500, 000 Cars ina Year . 72 Colored Telephone Poles to Liven Landscape . : 73 Tin Foil Amazingly Thin. 74 Did Man’s Legs Develop Before His Head?. . 74 — ‘@ Real Storm Warn- . Colored Snapshots—When? . ; . 150 The Men Prefer Blue . . 150 For the Home Owner Upholstering Old Chairs . 102 Fastening Objects to Plaster Walls . 127 How to Waterproof Shoes. . . 128 Hints for the Mechanic Timesavers for Shop Men 94 Old Bill Says— _ . 94 Turning Oversize Work ina Lathe. 96 Ideas for the Handy Man Now for Winter Sports . . 90 Choosing a Paint Sprayer . . . 100 Cannon for Shooting Snowballs. . 101 Blueprints for Your Home Work- shop . «aes Varnishes in the Home Workshop . 108 — for Bottom of Storm Doo: i

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This is the HOUSE that SCIENCE BUILT... a It Can Build a Prosperous Future for You! AA All the genius of our great inventors is em- bodied in the modern buildings which em- bellish our great cities. Hlumination, elevators, re- frigerators, heating sys- tems are but some of the attractions which make living desirable and en- ables modern properties to yield liberal returns on First Mortgage Real Estate Investments. V 6%% is the generous income of The F. H. Smith Company offerings. Invest your sur- plus earnings monthly, $10, $20, $50, or more, according to your income. In a surprisingly short time by our interest re- investment plan you be- come financially indepen- _ dent for life. Basic security of highly improved city office build- ings, apartment houses and hotels, plus numerous, positive safeguards — a development of 55 years’ experience — protect your investment. If you want to build, toward a Prosperous Future, send - for our two investment booklets telling how. Tue F H.SmitHCo. Investment Securities— Founded 1873 Smith Bldg., Washington, D.C. 285 Madison Ave., New York City Branch offices in other Cities eee eee ee eee eee eee eee eee) POPULAR SCIENCE MONTHLY — Imposing a Saving Sentence On a SPENDTHRIFT By WALLACE AMES, Financial Editor | I HE usual mess of monthly bills had arrived, checks were drawn and the accounts paid. In addition to the current household bills there were a number of extras representing Christmas presents, holiday expenses and one or two luxuries which Mr. and Mrs. Matthews had allowed themselves. All in all, after the bills were met there was just enough left in the bank account to see the family through until next payday. “Same old story,” remarked Mrs. Matthews in a sort of half-resigned, half- discouraged tone. “‘Another month goes by without our adding anything to our savings. It was the same all through | last year. First thing we know another new year will slip by and we won’t be any better off than we are now. How far did we actually get, Ralph, on that pro- gram we started a year ago New Year’s to lay by at least $75 each month?” “Not very far,” replied Ralph Mat- thews, himself none too well pleased with the way they were making out. “Of course we banked the Christmas check from the Company as a starter, just as we did this year. But every month during 1927 one thing or another took the money. Expenses, expenses, expenses, just like a pack of wolves, seem waiting to snap up each month’s salary the minute it reached our hands. ““When we were figuring things out the end of last year I was sure we could save $75 a month, and [I still know that we ought to have done so. It should be easy to save at least that much out of our income. But there was nobody making me save and every month—February, March, April and May—right through the year, we spent for one thing or another the money we ought to have put aside for the future. And it was the same the year before, and the one before that. Why is it that the habit of spending money is so much easier to form than the habit of saving it?” I Across the street lived a family whose circumstances were about the same as the Matthews’. But in their home, the same evening, quite a different scene was taking place than the one just depicted. Being the 10th of the month, John Max- well and his wife were also settling their monthly accounts. As the first order of business, Maxwell drew a check to a building and loan association. ‘Did you see this notice from the B. & | L., Olive?” asked John. “It says that after the current payment our shares ma- ture. We have been making these $75 monthly payments now for a little over 11 years. According to my account we have paid in a total of $10,200 . . , now we are going to get back $15,000!” “What a lot of money!” exclaimed Olive Maxwell. “What will we do with it? Of course, we have known it was coming some day, but now that the has almost arrived, I am overwhelmed! with the thought of having so much) money.” “I have been wondering myself what! to do with the money,” replied John,} “and I have an idea to suggest. We are! getting along nicely now, and do not need to draw on the income from oyr $15,009) . ..in fact, I see no reason why we should not keep right on saving out of our monthly earnings. But the idea] have is this: If we invest our $15,000 at 6% it will pay $900 a year, or $% a month. Why not use that to stat a new series of B. & L. shares? When they mature we will get another $1, 000, making $30,000 in all gained from the $10,200 we have now saved. That will put us on easy street.” ““That’s a peach of an idea,” Olive Maxwell agreed. * * * Both Matthews and Maxwell earned about the same salary . . . both families maintained about the same scale of living, There was only one important difference in the two as far as progress in getting ahead was concerned: The Matthews tried to save without a plan; the Maxwells saved with a plan. The Matthews saved what was left, if anything, after satisfying all their spending desires; the Maxwells saved first, and kept their spending within what remained. People who find it difficult to get ahead with regularity usually manage to pay their rent and household bills each month, but they do not put their savings and investments in the same class with monthly expenses ...as a_ regular monthly charge against income. If a man earning $6,000 a year should suddenly lose his position and have to take another pay- ing $5,000, his family would manage to get along on the smaller income. Thereis| room in any income for regular saving, if | it is planned for. The only way to get ahead is to.make your ‘savings just as rigid a charge against income as current expenses. For those who experience difficulty in saving with regularity, the Building & Loan plan is an admirable one to adopt. It demands regularity. And it pays @ handsome reward for regularity. It demands regularity not for just a year, but for a number of years, until the amount saved, and the income it produces amounts to a worthwhile sum. The Building & Loan plan originated oter a century ago, (Continued on page 6) RQeeer BDESEEERE ER SBESSE. February, ioe = | 4 BSeEEEE SE ‘= Sg In pl sh PES S ny $3 eS cman remedaace os ess" @eenrcno’o

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1Ce 0... $15,000!” exclaimed we do with own it was at the day erwhelmed| ; SO much yself what| lied John, st. We are lo not need ur $15,000 no why we ing out of the idea J ir $15,000 ar, oF $75 t to start es? When ther $15, d from the That will a,” Olive ‘ll earned h families - of living, difference n getting Matthews Maxwells WS Saved satisfying Maxwells ng within ret ahead > to pay h month, ings and iss with regular If a man enly lose her pay- anage to There is aving, if y to get just as ; current culty in Iding & > adopt. pays 8 ity. It a year, ntil the roduces ginated , page 6) February, 1929 Imposing a Saving Sentence on a Spendthrift (Continued from page 4) ‘marily as a means of aiding people to own their homes. But, associations have also achieved immense popularity among ple who want to save money. While uilding and loan associations vary in certain respects, the following points ap- ply more or less to all of them. A fundamental of all associations is their co-operative character. They oper- ate on @ very economical basis, have very little overhead, and all shareholders icipate on the same basis, according to the number of their shares, in the profits derived from loaning money to roperty owners. This co-operative feature enables share- holders to obtain an unusually high return ontheir money. The profit in matured B. &L. shares is equivalent to approximately 5% to 7% compound interest or 6% to 8% simple interest. One may deposit as little as $5 a month or as large a sum as he is able. On regular shares it is necessary to deposit the same amount each month. Many associations impose small fines on delinquents but these fines are used to swell the profits of all shareholders. The aggregate monthly deposits of shareholders is kept invested in real estate mortgages. Interest is not credited to shareholders’ accounts month- ly, or quarterly, as in a bank, but is re- invested and thus compounded. All the profits are paid at one time, when the shares mature. Each share matures at $200, representing approximately $138 savings and $62 profit. (The exact fig- ures vary, according to the profits the association gains from its investments.) Many associations also sell “‘full paid” or “income” shares. These permit out- right investment of such sums as $100, $200, etc., and pay a stated rate of interest—4 14% to 6%, according to the association. Building and Loan associations are sub- ject to state banking regulations and en- joy an honorable safety record. The B. & L. plan is fundamentally sound and the protection to shareholders compares with other safe financial institutions. * + + The great popularity of Building and Loan is indicated by these figures: For the year ended December 31, 1927 there were 12,710 local building and loan asso- ciations belonging to the United States League of Building and Loan Associa- tions; they had a total of 11,305,000 investors, whose savings and profits up to that date amounted to $7,062,525,000. The rapid growth of these associations in the last five years is shown by com- paring the above figures with those apply- ing to December 31, 1923, at which time there were 10,744 associations with a total membership of 7,202,880, whose savings and profits up to that date amounted to $3,942,939,880. ’ The outstanding usefulness of a build- ing and loan account is the fact that it makes saving compulsory; it forces the individual to save regularly and to keep it (Continued on page 6) POPULAR SCIENCE MONTHLY A vacation that lasts the rest of your life OW would youliketoquit work some day and start outon a vacation for the rest of your life? How would you like to pack your trunk, cash a good-sized check at the bank, pick up a traveler’s map and decide which part of the world you would like to visit first? Or perhaps you would prefer to settle down in a cosy cottage in the mountains or by the sea—a com- fortable place where you can spend the rest of your days just doing the things you’ve always wanted to do “when you had time.” Sounds attractive, doesn’t it! No more work. No more worries. Nothing but good times ahead, and of course, with all expenses paid. The money question But where is the money coming from? Who is going to pay your expenses? The answer is simple. All you have to do is to rearrange your present financial life slightly and the.money question will take care of itself. All you have to do is follow a simple but definite plan, and by the time you are ready to retire and take that vacation the money will be waiting for you. This plan was devised by financial ex- perts. It has been tried out by thousands of men and women. It is backed by a 100 million dollar Life Insurance Company. It is safe as a Government Bond. The minute you make your first deposit on this plan, its benefits begin. Your most important money worries disappear. You look forward to a comfortable future. You know that you need only follow the plan to be taken care of financially. vi And if you should become permanently disabled and unable to make further pay- ments on your investment, there would be no need for worry. Your payments would be made for you out of a special fund laid aside for that purpose. This Free Book explains it A 24-page, illustrated booklet, called “How to Get the Things You Want,” ex- plains the plan in detail. It tells not only how you can retire with an income when you are 65, but how you can leave your home free of debt—how you can send your children to college—how you can create an estate—how you can make sure your income will go on even though you should become totally disabled—how you can leave an income for your family. The financial plan outlined in this book is so clear and so simple that it can be un- derstood at a glance. It is so sound, so sensible, so logical that the minute you read about it you will realize that it works. Send for your copy of the free book today. There is no obligation, PHOENIX. MUTUAL LIFE INSURANCE COMPANY Home Office: Hartford, Conn. . . . First Policy Issued 1851 HERE are just a few of the things you can do under the Phoenix Mutual Plan: 1 Retire with an income when you are 65. 2 Leave your home free of debt. | 3 Senp your children to college. | 4 Create an estate. | 5 Makesure your income will goon even though you become totally ’ disabled. 6 Leave an income for your family, Puoen1x Mutvat Lire Insurance Co, 397 Elm Street, Hartford, Conn. Send me by mail, without obligation, your new book, ““How to Get THE Tuincs You Want.” DATE OF " eo nrte, BUSINESS ADDRESS HOME ADDRESS STATE

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Here is the ANSWER to questions which bother many investors How can you tell what gives a first mortgage bond absolute safety? How can you get the highest in- come from your money, consist- ent with safety? How can you select a safe invest- ment house? How can you retire in 15 years on your present living budget? ow can you get double the sav- ings bank interest rate or more, with all the convenience? How can you judge the security back of a first mortgage bond? What is the history of the first mortgage bond in Chicago? Why can Cochran & McCluer sell first mortgage bonds in every state of the Union without sales- men? All of these questions and many others vital to investors are answered in the new edition of a famous book, “Behind the Scenes Where Bonds Are Made.” Get your copy now. We’il gladly send it. No salesman will call. PRR REE SE SE a SS 3e88 oe Ph 2.5 . Cochran & McCluer Co. 46 North Dearborn St. ~ Chicago, Ill. m Gentlemen: Please send me without @ obligation your book, “Behind the @ Scenes Where Bonds Arc Made,”* No salesman will call. l Name 2 ad * = Address. * “ * City ___State SEeSBSBSBBBBeBBeeeaeaan Cochran & M‘Cluer Co. Established 1881 ever a loss to any investor 46 NORTH DEARBORN STREET Chicag io POPULAR SCIENCE MONTHLY | New Products Wanted for Manufacture An engineering firm of long standing has been requested to arrange contacts between holders of patented products and manufacturers seeking ad- ditional lines to manufacture. Only potented products, or those for which application for patent has nm made, will be considered. Sub- mit sufficient data to enable us to determine whether further negotia- tions are desirable. Address: P. O. Box 486 Grand Central Station New York City Imposing a Saving Sentence on a Spendthrift (Continued from page 5) up for a number of years, until his accu- mulations really amount to something. Another advantage is the fact that all profits are accumulated, re-invested and paid in a lump sum when the shares mature, instead of being paid in driblets. The most important result of this feature is the liberal profit ultimately paid to the investor. The Financial Department of PopuLar ScrencE Monts y likes the building and loan plan because it is a strong force in forming the regular saving habit, it pays the investor a liberal income and it is a convenient method for both well-to-do people and those in moderate circum- stances to provide for their financial fu- ture. Most every community has one or more building and loan associations, but those who do not live near one may invest by mail with any of the prominent associa- tions in New York or elsewhere. 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 ne rity. **55 Years of Investment Serv- ce”’ 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 alles. 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 wse insurance as an active part of your rogram for getting ahead financially. Phoenix Sacteal 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 lan will bring you financial: independence. Write for this booklet to Investors Spadicasn, 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. Bankers and clerks;merchants and salesmen;trustees and widows; doctors and nurses; lawyers and typists; senators and policemen; just everyone buys Fidelity Bonds. Why ? Because all prefer to invest their sur. plus funds in a manner that brings them the largest returns with the greatest margin of safety. Fidelity 6% First Mortgage Bonds offer both— a high rate of return and utmost safety for principal. Their payment, when due, is made doubly certain by our guarantee. Learn more about Fidelity Bonds. Send for the booklet, “Your Money—Its Safe Investment”. A copy is awaiting your request. We send it gladly, without obligation. I BOND * MORTGAGE ry J.U.MENTEER.Preudent mw INCORPORATED 199 660 Chemical Bidg., St. Louis 1188 New York Life Bldg., Chicago 378 Colorado Nat’! Bank Bidg., Denver FIDELITY MEANS KEEPING FAITH OULD you like to be sure of receiving $1,500, $5,000, $10,000 or more—in 120 months? We will unconditionally guarantee it to you in this time. If you want $5,000, for example, you invest $31.50 monthly for the period specified or you can start with as lit tle as $9.45 monthly for a guaran tee of $1,500. Write for booklet D-11 giving further facts, also ask for our financ statement showing resources of more than $22,000,000 INVESTORS SYNDICATE = Established 1894 ————> HOME OFFICE: MINNEAPOLIS, MINN. * New York Office: 17 East 42nd Street Offices in Principal Cities emoensre &@ LL ereenee ow "eorosa BBPonepe fe wes @ a ee

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New products andnew | methods make build- : ing a thrilling project. POPULAR SCIENCE MONTHLY Help for You in Building RE you thinking about building a house or modernizing your pres- ent home? If you are, you are in for a thrilling time if you take advantage, as you should, of the advances that have been made in the science of building in the last few years. There are today many new products and new meth- ods that you should know about before you build. Some will make for comfort, some for economy, and some for beauty. How are you going to learn about these wonderful new things and decide which ones you should determine upon for your new house or your remodeled home? The answer is the new Building Service of the Popular Science Institute, which is now available to our readers. The information that the Popular Sci- ence Institute has collected in your inter- est in connection with modern advances in home building has been obtained from every possible source where correct infor- mation could be secured. In many cases where there has been a difference of opin- ion in the value of a certain type of prod- uct, thousands of architects and building contractors all over the country have been consulted. Popular Science Institute has established in its building service a clear- ing house for facts and information such as exists nowhere else in the world and which will be of immense value to you or to every reader of this magazine who is planning to build or modernize a house. _ The Institute Building Service is not intended to take the place of the architect, the building contractor, nor any other essential factor in the building of a good home; its aim is to guide the man who is building a house and supply him with the sort of information that will enable him to make intelligent decisions as to what he will have in his house. The Institute is committed to the use of better materials, better methods of construction, and mod- ern equipment —even when a greater initial expense may be involved—provid- ing it is convinced real satisfaction and economy will result, justifying their use. You live now in a house that is heated in some way in winter (unless you live in the far South). Do you know how much of that heat is wasted; how much fuel you could save if the house were protected by one of the modern insulating materials? Do you know that immense improve- ments have been made in heating systems and the wonderful convenience and econ- omy that these modern heating systems offer? Before you build you should decide what kind of furnace you need; what kind of fuel you want, and what kind of heating system it is you should have. There is much that you should know about outside materials; about roofing materials, in which immense progress has been made and in which lovely effects can be ob- tained inexpensively. You should know the way that walls can be put up very in- expensively now, if one wishes to do it, and you should know the latest improve- ments in flooring materials. ND, too, there has been great progress in the matter of windows, in plumb- ing, and in refrigeration; and lighting is now a science that you should give thought to before your lighting system is installed. If you are living in an old- fashioned house, even though it may have been built many years ago at a time when everybody thinks of building as having been very substantial, you will probably find that cold air seeps in from a dozen points; through the ficors, through the walls, through the attic, all of which makes it almost impossible to keep the house warm at any cost. Whether you are planning to- build in the near future or not, you will be im- mensely interested in the series of articles that will appear in the coming issues of Popuar Scrence Montuty. These arti- cles are the result of reports secured in connection with every line of building material, and check-ups made with thou- sands of leading builders and architects, together with information obtained from Government bureaus at Washington. In questioning leading building con- tractors and architects regarding such modern features as insulation, scientific . heating, new building products, etc., the Popular Science Institute has found that practically every one of these alert men was most anxious to know what the con- sensus of opinion of his colleagues was on the same subject. If the information gathered by the Building Service of the Popular Science Institute is of value to these authorities on building, it will be doubly valuable to the amateur builder. WO things that you naturally want your house to have are the greatest amount of comfort and the most eco- nomical operation possible. ‘These things you can secure through the advice of the Building Service of the Popular Science Institute, based on careful, exhaustive research it has made on these subjects. The Advisory Board of the Popular Science Institute Building Service is headed by Prof. Collins P. Bliss, Associ- ate Dean of the College of Engineering, New York University. Working with him are William Dewey Foster, Practicing Architect in New York City and a recog- nized authority on the building of houses, together with George Allen Richardson, President of Geo. Allen Richardson, Inc., Engineers and Contractors, and also Con- struction Superintendent of the Eastern States Construction Co. The building articles to appear in Poputar ScrENcE Mon7uty will be written by experts and the new service will be in their charge. This Service is available to every reader of Poputar Scrence Monta y, free of charge. Address questions relating to building materials and equipment to the Popular Science Institute Building Ser- vice, 250 Fourth Ave., New York. ee eee ns? a in

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His Suleae Was Raised POPULAR SCIENCE MONTHLY | NEW WAGE $ CHEDULE while others were reduced “Up to the time I enrolled for a course with the International Correspondence Schools, I had only a grade-school educa- tion. Since enrolling, I have advanced to a much better position, where my salary is nearly four times as much as I was making previously. I would not be able to hold my present position had I not taken your course. Recently I received a nice increase in salary, while other men were being reduced.” Reap that last sentence again—‘“Re- cently I received a nice increase in salary, while other men were being reduced.” There could be no better proof of the value of an I. C. S. course than that. It shows that the trained man is given preference over all others and. paid more money, even in slack times, if his work deserves it. It shows that there are always bigger, better jobs open for men who have the foresight to prepare for them in spare time. Jesse G. Vincent was a toolmaker before he enrolled with the I. C.S. He is now Vice-president of the Packard Motor Car Co. Walter Chrysler, President of the Chrysler Corporation, is also a former I. C. S. student. So is “Eddie” Rickenbacker, the famous fly- ing ace, who is now Vice-president of the Rickenbacker Motor Car Co. - An I. C. S. course enabled Fred W. Southworth to leave a poorly paying job he had held for twenty years and get a position as a salesman. In six months he increased his salary 300%. George A. Grieble is another man who lifted himself out of the rut by spare-time study. He was a stone-cutter earning $15 a week when he enrolled with the I. C. $. He now has his own architectural and engi- neering business in Cleveland and his income is “between $10,000 and $15,000 a year.” University of the Night” The home of the Fotireatlondl rremuce Schools" The If the I, C, S. can help these men to get out of the rut and make good, it can help you too, If it can raise the salaries of other men, it can raise yours! At least find out how. The way is easy! Just mark the work you like best in the coupon below, Then mail it to Scranton today. This doesn’t obligate you in any way, but it brings you information that may start you on a successful career, This is your opportunity. Mail Coupon for Free Booklet INTERNATIONAL CORRESPONDENCE SCHOOLS “The Universal University’’ Box 7613-F, Scranton, Penna, Wiest cost or obtication, ease send me a copy ¢ “Who Wins i Why * and full your booklet, about the subject before ‘nich I _-* marked BUSINESS TRAINING COURSES Business Management Advertising Industrial Management English Personnel Management Business Mey pe Traffic Monson" Show Card and Sign Accounting and Coaching Stenography and Typing Cost Accounting Civil Service Bookkeeping Railway Mail Clerk Salesmanship Common School Subjects Secretarial Work Buieh School Subjects Spanish [ French Illustrating [) Cartooning TECHNICAL AND INDUSTRIAL COURSES Electrical Engineer O Architect Electric Lighting (J Architects’ Blueprints Mechanical Engineer Contractor and Builder Mechanical Draftsman Architectural Draftsmaa Machine Shop Practice Concrete Builder Railroad Positions Gas Engine Operating Civil Engineer () Mining Surveying and Mapping Structural Engineer Chemistry [) Automobile Work Airplane Engines Plumbing and Heating Agriculture and Steam Engineering [) Radio L) Mathematics Hil iscascdgutssctinsanninintiaisetinnen ‘ Street Address ji iii acetikennmsnpiiibabeteniaiaticareniannentitantemaniaiad State. Tf you reside in Canada, send this coupon to ‘the ‘jnterme tional Correspondence Schools Canadian, Limited, Montreal

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February, 1929 Manufacturers and inventors POPULAR SCIENCE MONTHLY use this grailess wood to make good products better The making of broad pieces, peculiar shapes and curved surfaces often makes it difficult to obtain low cost production. But Masonite Presdwood solves these trying problems. This grainless wood is readily cut, sawed, punched, or curved. It resists moisture and takes any finish. Write for a generous sample. Then try it for yourself. FOR RAILROAD COACH 2d d make an raise an raise ark the 1 below, y- in any ion that »oklet a copy f Reports of new uses for this grainless wood are coming in daily. A manufacturer solves a production problem, cuts costs or widens his market. A mechanic develops new ways of working and finishing it. An inventor finds it meets requirements better than any other material. And—three years after placing Masonite Presdwood on the market—we, who make and sell it, are still wondering just how far its range of usefulness will finally extend. CEILINGS Builders of fast motor boats and outboard hydroplanes say that Presdwood gives their craft lightness, strength and speed. Contractors use it for concrete forms because the resulting smooth surfaces cut their labor costs to the bone. And from far and near come orders from makers of road signs who wish to take advantage of Presd- wood because it is easily worked and quickly painted. Presdwood IS wood Presdwood is made of wood—exploded to sep- arate the fibres—then formed, with heat and enormous pressures, into uniform boards, 14 inch thick, four feet wide and twelve feet long. The same wood binder (the lignins) that held the wood fibres together, again cements the fibres of FOR CONCRETE FORMS ON FACADE ARCHES Presdwood, but now there are no knots, no grain, and no cracking, checking or splitting to mar the beauty of the fin- ished product, or worry the manufacturer. Where broad surfaces, beau- tifully finished, are essential—there you will find Presdwood. It is used in paneled walls of apart- ments and office buildings. It is used for broad FOR BEDROOM SCREENS side panels of motor truck bodies and the interi- ors of Pullman cars. And in the moving picture studios of Hollywood it is artistically employed to portray the ballrooms of the rich and the palaces of kings. Does not warp resists moisture Because of its freedom from warping and buck- ling, and because of its resistance to moisture, we find Presdwood used for thetension boardsof radio loud speakers, for bedroom screens, work bench tops, campers’ tables, bread boxes, dairy product containers and starch trays for candy factories. And when you try Presdwood for yourself, you will find that it will solve a manufacturing problem, reduce costs or make a good product even better. Write for a large free sample. It will be sent promptly on request. MASONITE CORPORATION Sales Offices: Dept. 722° 111 W. Washington St. : Chicago, Illinois Mills: Laurel, Mississippi FOR MOVIE STUDIO SETS asonite | XII PRESDWOOD {Et ye Made by the makers of MASONITE STRUCTURAL INSULATION 13

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POPULAR SCIENCE MONTHLY February, 199

Eyeglasses a Fad? | WAS amazed that either Porutar Scrence Montaty or Dr. Free, whose articles I usually read with interest, should fall so hard for the propaganda of oculists and opticians as to publish that article, *Must We All Wear Glasses?’ “What we need is not more glasses, but fewer glasses. Having eyes examined has become as rauch of a fad as removing tonsils and (a few years ago) cutting out appendixes. Indeed, I em convinced that the style of wearing’specs, far from being a remedy, is one of the chief causes of America’s failing eyesight. “Take my own case. Three years ago my vision seemed perfect, I found no trouble read- ing anything and everything. But, being con- fined to close office work, my eyes would feel * tired at the end of the day. A friend advised me to consult an eye specialist—and, of course, he prescribed glasses. The only difference I noticed was that the lenses slightly magnified. But, after wearing them a few weeks, I found I had become their slave. If I tried to read without them, a headache was sure to follow. The only result of glasses for me was weakened eyes, and the only profits went to ‘specialists’ who designed and made them.”’—A. R., Chicago, IIl. It Rained Salt Water! ’ ITH reference to a recent item on water- spouts in your magazine, I would like to add what seems to me to be an important cor- rection to the statement that ocean water- spouts are not salty. “Several cases are on record in our files of waterspeuts that unquestionably carried sea water. Weather reports from seamen have told of salty spray being thrown on deck by passing spouts, and have mentioned the fall of salty rains from spout-bearing clouds. “About two hours after the disappearance of the famous water- spout of August 19, 1896, off Marthas Vine- : , residents of the island were astonished by the singular fall of rain which they said was salt to the taste. The spout had an estimated altitude of 3,600 feet, and a quantity of sea water had been drawn to such a height and distributed about in the attendant cloud mass to such a degree as to affect the freshness of the rainfall. “Now, while the greater portion of the or- dinary funnel is undoubtedly composed of or- dinary cloud matter—a condensation product —-yet in local ocean whirls of great intensity it should be no more surprising that some sea water may be caught up and borne aloft, than that tornadoes on land should pick up wreck- age, carry it to a great height, and bear it to some distance from its place of origin.” — W. E. H., Weather Bureau, Washington, D. C. Thanks, Doctor “Wits , recent article, ‘A Mystery of the B Solved,’ was a ‘diagrammatic drawing of the heart and the circulatory system. Out of thousands of drawings I have seen and

studied, mostly in medical journals, and occa- sionally in lay journals, this drawing is by far the best. It is even instructive to me, who has dissected many hearts and examined thousands of patients for possible heart disease.’’—Dr. J. E. E., Grand Forks, N. D. Airplanes and Death “T READ with some amusement the sarcastic letter ‘from a hero worshiper,’ in which §. T. R., Jr., in- ferred that the Wright brothers, by inventing the airplane, foisted upon the world an evil machine of death. And it occurred to me that if the writer, instead of ranting about ‘bloody Sundays in the air,’ would take the trouble to learn the facts, his fears might be relieved. ** A recent official report of airplane accidents during the first six months of last year lists 390 mishaps, in which 153 persons were killed and 276 injured. At first glance this would seem a

heavy toll, until we read further that in sched- . uled flying over established air routes, there were only six fatal accidents. The great proportion of fatalities occurred in ‘miscel- laneous flying,—races and other contests, ocean flying, and experimental flying. **And the airplane casualty list grows even less imposing when we turn to another report, recently issued by Louis I. Dublin, statistician of the Metropolitan Life Insurance Company. It shows that in the supposed security of American homes, 25,000 men, women, and chil- dren were killed by accidents during 1927! Of these 8,750 were killed by falls. “TI don’t contend that the airplane is fool- proof. But compared with the hazards that surround us every moment, airplanes offer little to fear.” —H. N. P., Detroit, Mich. Good Enough to Fly “T WISH to compliment the artist who painted the picture for your December number on his ability to a mechanical devices. The plane is one that any pilot would be glad of the opportunity to fly. It would be my suggestion, however, that before the pilot of this particular plane revs up his motor very fast, he have his mechanic change the propeller. It would be hard to say just what to expect if the present one were left on the motor. At least he couldn’t expect to gather much head- way.”—L. B., Urbana, Il. Saved Their Money ‘T READ with profit Alexander Senauke’s article about the new radio gyps and their trick aerials. My receiving set is nearing com- pletion, and I was about to send for a certain underground aerial. In this letter I hope to express my gratitude to your magazine for good advice. I believe I am one of thousands that profit by the ‘Institute of Standards.’’’— R. S., Hastings, Mich. “Today I received a let- ws: ter soliciting my order for

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‘s Montaty 1g, stimy. e Cod; 89 ir Corps, gliders, ] built for long to to ina en late st saw A. C, >ment, PULAB MONTHLY — FEBRUARY, 1929 SUMNER BLOSSOM Editor VOL. II4, NO. 2 —. COAL from CABB By supplying fibers for our clothes, wood has “taken the candy”’ away from the cotton plant and silkworm. A modern magcician —Dr. Fritz Hofmann (left), chem- ist, explains how he makes synthetic rubber from coal. ob GES With clothing of thin alumi- num in place of wool or cot- ton, the well dressed man may Tival armored knights of old. And food from sawdust, lemonade from peanut shells, lumber from straw, cotton from banana stalks! story of chemistry’s latest magic. venture, wonder and romance right at your door N THE speaker’s platform in the auditorium of the Carnegie Institute of Technology at Pittsburgh some weeks ago, an unassuming man, hailing from romantic old Heidelberg, the famous university town in Germany, stood and announced in matter-of-fact tones that, after twenty-two years of experimenta- tion, he had succeeded in making coal out of wood, cabbages, and cornstalks! His low-voiced, undramatic reading of a highly technical paper was followed by an ovation from an otherwise austere and undemonstrative gathering of distin- guished scientists from many lands, who were attending the second Inter- national Conference on Bituminous Coal. Dr. Friedrich Bergius, the speaker, had taken eleven pounds of cellulose, a chem- ical derived from various plant and vege- By GROVER C. MUELLER table substances, mixed it thoroughly with water, and placed his solution in an air-tight vessel. Then he had heated it to 640 degrees F. and put the container in molten lead. After allowing this sealed cooking to continue for twenty-four hours, he had shut off the terrific heat, let the accumulated gas escape from the vessel, and waited for the liquid to condense. Result: eleven pounds of coal! But in a broader sense, Dr. Bergius had done much more than that. He had leaped across the chasm of the ages and, in twenty-four hours, produced an in- dispensable substance which it takes nature twenty-four hundred centuries to create! Overnight, he had challenged her seemingly immutable laws with an invention which may avert fuel famine for untold future generations. At the same conference, Dr. Carl More amazing than a fairy tale is this Here are ad- Krauch, director of the German Dye Trust, fascinated the delegates with a description of the making and marketing of synthetic gasoline, obtained from soft coal. This year, a production of 70,000 tons was reached by the plant of the trust at Leuna; next year, an output of 250,000 tons may be attained. ROM a business and scientific point of view, this is what happened: There was a shortage of oil in Germany; the price of the fuel had become exorbitant. Chemists of the nation set to work and turned coal into oil by various methods. In a way, it was a duplication of what Germany did during the World War; when, with nitrates cut off by a ring of warships, German chemists reached into the sky to take out of the atmosphere the artificial ammonia which had hitherto 17

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eer FERTILIZER POPULAR SCIENCE MONTHLY GASOLINE FATTY FOOOS. Here are just a few of the important articles in common use which now can be made from coal and its by-products by the magic of chemistry. Dyes, perfumes, even wax, are among others on the list. been imported, in the form of nitrates. from Chile. But think of the deeper significance of this synthetic oil discovery! Consider its effects upon international relations and the peace and prosperity of mankind! What these chemists in their laboratories really did was to take the germs of another world war, put them in the test tube, and dissolve them out of existence! The con- flict they averted was the giant struggle over the diminishing supply of the world’s natural petroleum, which the great pow- ers were supposed by some observers to be preparing. While demands for oil are growing by leaps and bounds, the avail- able supply gives no promise of lasting longer than until the end of this century. And so, the pessi- mistic prophets of international rivalry predicted, there was no other way out for the nations but to engage in a death-grapple for the control of the precious liquid. O SOONER had Dr. Krauch .% finished his address, than F. X. Zur Nedden, secretary of the fuel committee of the national council of Berlin, told the assem- blage of the vast economic advan- tages of the use of coal liquefied by a process of distillation! This method not only tends to diminish the importance of the earth’s slowly vanishing coal supply, but it does away with the cumbersome weight and the ballast of ash and humidity inherent in the fuel’s present form. And another German scientist, Dr. Fritz Hofmann, revealed that he had produced rubber from coal in his laboratory. For the time being, he explained, the synthetic product is more expensive than natural rubber, but he is hopeful, through future experiments, of making arti- — rubber on a large commercial scale. Artificial silk from peanut shells! Dr. S. J. Lynch, of the U. S. Waste Utilization Service, demonstrates here how it is done. Thus the conference presented an array of amazing discoveries showing that the dreams of the scientist are being turned into actualities that are bound to change the complexion of business and industry and make their benefits felt in the homes and daily lives of millions of men and women the world over. Not only oil from coal and coal from oil, coal from cabbages and rubber from coal, but burnable gas from water, wood alcohol from coal, soap from coal, and even edible fats from coal—the day of synthetic bacon may soon be upon us!— were among the completed achievements or promising potentialities the scientists February, i9y at the convention had added to the Won. ders of modern chemical industry, That industry now produces coke more Useful than raw coal, dyes in colors more daz. zling than the rainbow, perfumes more fragrant than flowers, and many othe artificial articles that surpass Nature's own handiwork in providing humajit with comfort and pleasure. ’ peed before the conference in Pittsburgh convened, Dr. A, 9 Jaeger, an American chemist, announced two new processes, involving the puri fication of anthracene, that will give the dye industry in this country an untold wealth of raw material now locked away in the black heart of coke and coal tar, About the same time C. H. McDowell, president of the Armour Fertilizer Com. pany, of Chicago, disclosed the invention of a method of extracting fertilizer from coal which will prove invaluable to oy farmers in the raising of corn, winte wheat, and cotton. The plant food was discovered as a by-product when am. monia was eliminated from illuminating gas to obviate its unpleasant odor. A few weeks previous, two Germay chemists triumphantly informed the world that, after years of fruitless at. tempts, they had succeeded in making food out of wood, or, to be specific, sugar out of sawdust! And on the heels of this announcement came the still more a. tonishing news from France that a scien. tist there had transformed coal into diamonds which, ere long, may grace the throats and hands of our American beauties! This series of scientific events once more threw into bold relief the fact that the chemist has not only inherited the cloak and improved upon the arts of the alchemist of medieval times, but that he is the modern counterpart of the ma gician of the dark ages—the Merlin at the court of the Average Man, whois king in our day of democracy. UT unlike the practitioner of “black magic”’ centuries ago, the present wonder-worker does not aim to mystify and bewilder his fellow men. On the con trary, it is his purpose to clarify for them the blind and seemingly inscrutable forces that surround them on every hand Nature, and to enslave these powers for their greater happiness and well-being. The day is coming— Chemists have has, in fact, arrived— founda wayto when the chemist feeds turn waste saw- dust into food US; Clothes us, heats and foranimals. lights our houses, and sup- plies essential fuel for the machines that transport -: us and make our daily oD pot necessaries. worms Coincident with the pest news that scientists had awD vST | managed to turn sawdust +) p POR K. | into food, came the report F —- that a German chemical laboratory was be ginning to turn out clothing made from aluminum in thin sheets to take the place of wool and cot- ton. And Dr. Warren E. Emley, of the United States Bureau of St shell deta the!

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‘bruary, 199 0 the Won. try. T ore usef yl more day. mes More any oth ) Natures humanity erence jp’ a 0 nounced the puri. l give the an untold ked away oal tar, [cDowell, zer Com. Invention lizer from le to our n, Winter Was rhen am. minating or. German ned the tless at. ._ making fic, sugar 1s of this more as. t a scien. oal into zracc the \ merican nts once fact that ‘ited the ts of the put that the ma- ferlin at who is ‘ ce black present mystify the con- or them le forces rand in vers for eing, ming— rived— t feeds ats and ind sup- for the ansport r daily th the ts had awdust report emical us be rn out . from 1 thin e the nd cot- Varren f the sureau February» 1929 t Standards, told a meeting of members “t the American C hemical Society recent- h that a lemonade made out of peanut hells and bran would soon be ready for . mmerce and consumption. One of the Setails that await further perfection is the name of the beverage, which at pres- nt, for lack of something shorter and a eiticn, is called “xylotrihydroxyglutaric Pid”! ‘But what’s in a name? UNDREDS of other chemists H throughout the world are engaged in transmuting waste into matter useful to mankind. They, too, are magicians of modern science. A young Philippine chemist by the name of Balingao not long ago invented a substitute. for. cotton fiber which he produced from hitherto worthless banana stalks! The process, resembling mercerization, consists of “cracking” Off the cellulose binding of the fiber, which leaves it pure white and ready for weaving without having to be spun first. - : Large quantities of straw in the cereal regions of our Middle West, where there are no forests, are being turned into ma- terial for insulating building boards. Its fibers are cemented together in long filaments. In the laboratory of the U. S. Bureau of Mines at Pittsburgh more than three gallons of wax recently were extracted from one ton of Utah coal! First, thirty- two gallons of tar were taken from the coal, and further experiments made the tar yield eleven percent of wax. The POPULAR SCIENCE MONTHLY chemists who made the discovery de- clared that great quantities of wax, in no way inferior to the stuff now used in candles, may be produced from tar with little effort. A little bird literally told English re- search workers in British Guiana how to obtain a substitute for cotton from a useless plant. This feathered fellow was seen building his nest with materials that looked like cotton, but which proved to be — plant stripped and treated by the ird. The investigators brought the seed and roots to England. That was eight years ago. Now, between three and four mil- lion pounds of this artificial cotton is being grown on soil in Essex and Sussex counties that had been considered of no use for any sort of vegetation. And not only has the ground been put to good use, but the substitute cotton, which is said to be as good as the real article, is eight cents a pound cheaper. TE transmutation of sawdust into food—one of the most striking ex- amples of utilizing waste material— was accomplished by the simple process of adding one molecule of water to one molecule of cellulose, which with _ lignin is a principal constituent of wood. This chemical reaction had been known for more than a century, but until the two German scientists thought of it, the idea that, in this fashion, the enormous amount of waste wood contained in saw- dust—about forty percent!—could be turned into food for animals PERPETUAL MOTION ! 194 and, eventually perhaps, for men, too, had never oc- curred to anyone. Only very recently, mod- ern alchemists of chemistry discovered that seaweed could be turned into gold— but, of course, indirectly. On the Pacific Coast, a great seaweed. industry has lately developed. It was Lemonade made from pea- nut shells and bran soon may be a popular beverage. For this we have the word of Dr. Warren E. Emley, of the United States Bureau of Standards (shown at left). Oif from coal and coal from oil—coal from cabbages and Tubber from coal! New marvels spring from the chemists’ magic crucibles. By brewing cellulose taken from wood, cabbages, and cornstalks, Dr. Friedrich Bergius, of Heidelberg, Germany, produces coal. This photo shows him in laboratory with jar of the synthetic fuel. 19 James Basset, French chemist, and appara- tus with which he claims to make dia- -monds by subjecting coal to great pressure. discovered that this “worthless” plant contained properties similar to starch and gum arabic; in fact, it is superior to both, as it has fourteen times the stickiness of starch and thirty-seven-times that of gum arabic. It “fills” cloth better than starch and leaves it thick and elastic in- stead of stiff. Chemists predict that it also will prove highly useful in dyeing and color-printing and that, before long, we may even eat it, mixed with certain other foods! HUS, in a hundred experimental lab- oratories, chemists are finding ways of utilizing the things which we now throw away. And yet—curiously enough—the waste piles of the world continue to grow larger. Why? The answer is that there is more to the problem of utilizing waste than finding how to make it into some thing useful. There is the problem of transporting the waste to the factory, or the product to its ultimate market. It is, of course, of not much use to spend time and money in reclaiming waste until there is a market for the re- claimed product which can be reached at a cost which will yield a profit. The new straw lumber developed in the Middle West, for example, is intended for use only in the treeless wheat country, where ordinary lumber has to be brought from a distance at great expense. But the prod- uct of the straw stacks cannot pay trans- portation charges to distant markets, even if it could compete with wood in markets where lumber is cheap. Scientists, as a rule, are not business men and, fortunately for the sake of hu- manity, they persist in their investiga- tions and laboratory experiments regard- less of possible commercial obstacles. An ideal condition, of course, would be the utmost codperation between chemistry and industry. And this is now coming to pass. Day by day, natural science and business are being linked more closely to- gether. In this way, an invisible bridge is built that connects the wonderful dream- world of the laboratory with the living reality of your home and mine!

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The Story of One of the World’s Most Thrilling Engineering Feats—Giant New Hudson Span Will Carry a City in a Day! By EDWIN KETCHUM MAGINE all of the men, women, and children of Baltimore, Md., leaving their houses on a sultry August morn- -™. ing and piling into automobiles to rush away from the heat of the city. Then picture this huge procession of automobiles,—about 200,000 cars in a line that would reach two thirds of the way from New York to Chicago!—passing in that one day across a suspension bridge of a single span 3,500 feet long, and you have gained an idea of the tremendous traffic to be borne on a summer Saturday by the greatest bridge in the world. Realize, next, that all of these cars with their four fifths of a million passengers, besides hundreds of buses and electric trains, thousands of pedestrians, and the raammoth weight of the bridge itself, will be supported by four cables over a dis- tance of fourteen city blocks, 200 feet above the water, and you have a concep- tion of the boldness and magnitude of one of the most wonderful engineering feats ever attempted. But such a giant bridge does not exist, you say. True! It will, however, be a monumental reality within a few years. In 1932, the new Hudson River bridge, dwarfing all other structures of its kind, will stretch across the Hudson from Fort Washington, in New York City, to Fort Lee, in New Jersey, giving New York a great new gateway to every part of the United States. The main span of this titan among bridges will be twice as long as that of the 1,750-foot Philadelphia-Camden crossing which, since its opening in 1926, has held the record of being the world’s longest suspension span. And the famous Brook- lyn Bridge, with its 1,595 feet, will seem almost insignificant beside it. Fourteen traffic lanes, including eight roadways, two sidewalks, and four elec- tric railway tracks, will accommodate its unprecedented traffic. It is expected that 40,000,000 automobiles will eventually cross itin a year! Its total cost will reach $60,000,000. The height of its finished cable towers —635 feet—will exceed that of the Wash- ington Monument by eighty feet and that of the Singer Building, in New York, by twenty-three feet. They will hold a 90,- 000-ton fabric of steel and concrete in mid-air—twice the weight of the steam- ship Leviathan! The carrying cables will have a capacity of 350,000 tons, compared with 120,000 tons for the cables of the Delaware Bridge and 45,000 tons for those of the Brooklyn Bridge. It is estimated that in the first year of operation 8,148,000 vehicles, containing some 19,000,000 passengers, will move across the new span, in addition to 1,500,-

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once ACROSS THE HUDSON RIVER TWEEN T WASHINGTON AND PORT Tee This comparison gives an idea of the gigantic proportions of the new Hudson suspension bridge. Its central span will be twice as long as that of the record-breaking Philadelphia- Camden bridge across the Delaware. And it will dwarf the once famous Brooklyn Bridge. & wwe al nanereeons 7

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POPULAR SCIENCE MONTHLY a1 of The imposing ap- Ls : proach to the Hud- son bridge on the New Jersey shore, as it will look when fin- ished. Here the huge suspension cables will be anchored in solid rock. Eight roadways will accom- = gut modate 200,000 cars in a single busy day! PIE es — oe es eee cement eee ep og a Ce} Phen 7 i ( 2 Tower and approach on the New York side, as they will appear from the river. Tower : as contains 20,000 tons of steel. No place for weaklings. Knit- ‘ ting together enormous steel gir- ders 500 feet above the Hudson. Right: At dizzy heights above city roofs, the bridge workers balance on narrow steel beams. Below: Constructing concrete tnillion anchorage for the bridge cables on the New York side. This mountain of concrete covers n com- almost a city block and is as de pos- high as fourteen-story building! neering | opera- @& man- or. For ith the id rock Jersey cting & y match lasting 27, the ceeding sement young vays i y> stir- Giant fingers of steel begin to reach across the river. It’s rtually a thrilling job, and one of the mightiest engineering feats . ever attempted. This photograph gives an idea of the tremendous size of the girders used in the construction of ‘s that towers that will hold a ninety-thousand-ton fabric of steel nark— and concrete in mid-air above the mighty Hudson River. ige 144)

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1% a - Seuffing Out a Giant Candle Fire Fighters, Behind Shields of Steel, Win Terrific Battle with a Flaming Oil Gusher By JOHN E. LODGE OOT-SMEARED, an oil driller races across the sand. His face is distorted with fear, his undershirt scorched. Behind him, amid a cluster of twenty oil derricks like ant hills on a desert plain, a pillar of flame shoots skyward. One of the towers rises bodily into the air, and is hurled in a dozen directions. A deep, rumbling crash, and the ground under his feet quivers like jelly. That was the scene when Bellevue No. 1, latest oil gusher in the rich Santa Fe Springs field near Los Angeles, Calif., ““came in” the other day. When the drill point tapped an underground lake of oil, a column of | the liquid spurted high in | the air. Underground rocks came with it. A_ stone struck the casing. Sparks flew. In a _ second the gusher had become a 200- foot-high candle of flaming oil. Near-by derricks toppled, weakened by the frightful heat. En- gineers advanced into the black smoke clouds, under pro- tecting water streams from hoses, to raze more derricks and check the million-dollar fire’s spread. How can one of these spouting infernos of liquid fire be extinguished? This was not the first time an untamed oil geyser has menaced its drillers with fire. Lightning has made oil derricks its tar- get and turned productive wells into death traps. Sometimes a _harmless- ooking grass fire touches off a well. Whatever its cause, a flaming pillar of oil, hot enough to melt a derrick’s steel, is not a pretty thing to pvt out. ; Yet engineers have dared to attack these fires, with sensational success. One of their recent triumphs, oddly enough, has been just half a mile from the scene of the latest oil fire, where a novel system of ~ putting out an oil blaze received a spectacular demonstration. For eight weeks a freak POPULAR SCIENCE MONTHLY fire raged about what had once been the derrick of Getty No. 13, in the same Santa Fe Springs field. Dense smoke billowed from the flood of seething, flam- ing oil, while above roared a smokeless jet of fiery gas. Advancing behind steel shields. to screen them from the heat, fire fighters approached the ‘terrific blaze. After a brief perspiring survey, they decided to Clad in asbestos suits, like that shown at the right, fire- fighters attack the flaming well, advancing under the protec- tion of steel shields that screen them from the intense heat. A breath-taking moment during the Bellevue No. 1 oil gusher fire. weakened by terrific heat from the 200-foot pillar of flame, topples and crashes. \ at ieft shows the five-ton steel cap which snuffed out a previous fire in the same field. February, 19 A huge derrick, Photo try a desperate experiment—to snuff it out, like a giant candle. First, a sapping project reminiscent of those of the World War was carried out, Under cover of the shields, tunnelers bur. rowed into the earth and dug an under. ground shaft two hundred feet long to pierce the main casing. Through it, sixty feet beneath the ground, quantities of gas and oil were diverted and the force of the burning jet diminished enough for the daring attempt. O SNUFF out the “candle,” the men chose a five-ton cap of steel that looks like an inverted funnel. Its top is a stack with a huge valve, while at the wide. mouthed base is another pipe, with a valve, to lead off unburned oil. Tractors and a daring crew popped this cap over the burning well. In stantly the funnel stack became 4 flame-spouting chimney. A turn of the valve wheel in the stack, and the flames went out—the pipe was plugged and the fire smothered. A __ hoarse command, and the valve on the lower pipe was opened in time to save the whole five-ton cap from being blown off by the accumulated pressure. Harmless oil poured out into a pit. The fire was out! Often nitroglycerin is used by the asbestos-clad men who extinguish well fires. Chargesof explosives dropped into the blage and exploded __liter- ally blow the fire out.

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lerrick, Photo e field. snuff it iscent of ried out, lers bur. n under. long to it, sixty es of gas ce of the for the the men at looks : a stack ie wide. with a popped ell. In. came 4 turn of ek, and ipe was re fire hoarse e valve pe was save the p from by the essure. red out t! erin is -os-clad ish oil urges of ropped blaze | liter- ire out. s and cover it with earth at one time. By o HOMER CROY -°~};:2 | BRUARY brings to mind that r two Presidents, both born in the same month, were, in their own right, inventors. They are George Wash- ington and Abraham Lincoln. And in their inventions they showed their different natures. We'll take Washington first because he came first. Washington was the richest man in America; a country gentleman. J"e had an unswerving passion for prac- tical things. Figures and exact quantities especially appealed to him. Once he set two workmen on his estate to counting how many seeds were in a bushel of clover. It took days, and when it was finished he carefully made a note of it. Washington, on account of his social position, entertained a great deal. At his dinners he always served wines. One day as the bottles were going around he noticed that there was some confusion as to which bottle was which and what was what. His practical mind immediately fastened on it; here was something that needed remedying. He invented a device holding four bottles and which could be passed around so that all the bottles came to a guest at the same time. From these he could make his choice. In his own words Washington said of the contrivance: “It will be more conven- | ient for passing the bottles | from one to another than handling each bottle sep- arately, by which it often happens that one bottle moves, another stops, and all are in confusion.” The idea was similar to a caster, or a cruet for condi- ments for the table, except that it was more elaborate. It consisted of a little platform mounted on wheels so that the device with its Washington invented a plow tosow -— f POPULAR SCIENCE MONTHLY ' Washington anil? = Lincoln Both Were Inventors freight of wines could be rolled along the great dining room tables used in those days. It was given the name of “coaster,” s.it could coast around the table. The inven- tion was pronounced a great success, and was taken up by the gentry of Virginia to such an extent that no formal dinner was considered correct unless it had a Washington wine coaster plying up and down the festal board to serve diners with the wine of their choice. A wine serving device! Can you imagine Abraham Lincoln—that simple, homely son of the soil—inventing such a thing? What next did the industrious, prac- tical, Washington make? This time it had to do with his estate. It was a plow. He had seen a plow which had been brought over from England, and imme- diately his practical mind worked out an improvement. Then he called Peter, his smith, and set to work constructing it. The plow, when fin- ished, develop- ed. the curious eccentric- ity of not want- ing to stay in the ground. Washing- ton designed it New Light on the Great Presidents Whose Birthdays We Are Celebrating This Month all over again. At last the idea was whipped into shape, and then Washing- ton proudly brought out two of his hand- somest carriage horses and attached them to the plow. It nearly ruined the horses, for the ground was rocky and the plow began to jump, and the horses started to run away. Later, work horses were sub- stituted and the plow was a success. Twenty-eight years later Washington, returning to the idea, designed a plow which would do two things at the same time—sow the grain and plant it. It was a brand-new idea in agricultural ma- chinery. Part of the device was in the shape of a barrel which discharged the grain, while behind was a roller which broke up the clods and kicked earth over the seed. ASHINGTON never tried to make money from his inventions and they were never put on the market. But as President he encouraged inventions; he signed the first patent law passed by Congress and attached his name to the first letters patent issued by the United States. Lincoln had no interest in stately din- ners where a wine coaster would be a useful and pleasing device, or in farming. He was born on a farm and got off it just as quickly as he could. - Lincoln turned to some- thing he knew about. River boating. When Lincoln was twenty-one years old he went on a trip down the Mississippi River to New Orleans on a flat- boat and for the work he did he received the salary of twelve dollars a month. He got as far as New Salem, Illinois, the bot- tom of the boat grated on a mill- dam, and stuck. Nothing under high heaven could budge it. The front part ‘Continued on page 137)

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2 een = “ pe A ence ena ase Animals Really @® Can Think IS four shaggy feet firmly planted upon an exquisite $10,000 Persian prayer rug, a Shetland pony stood in the middle of the drawing room at the New York home of Sir Joseph Duveen, internationally known art con- noisseur and antiquarian, one evening a few weeks ago. All but speechless with amazement, a brilliant gathering of ladies and -gentle- men in evening dress sat in a semicircle around the little horse. Theirs was the thrilling experience of seeing the fairy tales of their childhood come true. For here, so close that you could feed him lumps of sugar by «stretehing out your hand, was a real, flesh-and-blood animal that could “think and talk” in a manner of which Hans Christian Ander- sen and the Grimm brothers never dreamed in their weirdest fancies! Why, this marvelous pony could an- swer any question you asked him! And POPULAR SCIENCE MONTHLY 4 Ss -\) "4 v | \\\ iy NY . “ | j it] JAAN ah ie Pi NM uh whe weit F By ROBERT E. MARTIN times whether animals really can reason and think. At the recent International Congress for Psychical Research in Paris, the subject, of long scientific conflict, was widely debated. Here Mr. Martin tells of some amaz- ing examples of seemingly human in- telligence on the part of animals. No person, possessed of the slightest curi- osity—whether he believes that these resulted from reason or from instinct and training—should miss this ab- sorbing, article.—The Editor. \ times everyone has wondered at such questions as they did put to him! And what answers he gave! The little horse had been placed before two openwork fences on which were hung small tin triangles, each bearing a letter of the alphabet or a numeral from one to nine. By picking off these tabs, the pony quickly spelled out his startling answers to a rapid fire of questions “shot” at him by members of his “‘audience.” H Vb AMMA AMINA ! aM TORMEARARARINAAMRA Ta ae Mr. and Mrs. Tiger re- membered! When their keeper advanced, holding a painting of an African big .game hunter, the beasts screamed and fied. Amazing Stories of Tigers that Reason, a Horse that Solves Deep Problems, and an Ape that Invents The animal’s replies gave evidence d an almost fantastically human intell- gence. He could distinguish between men and women. He told the time. He gave the dates of historical events. He added and subtracted and—solved square-root and cube-root problems! But judge for yourself whether this pony thinks like a man or not. The *“‘conversation” ran as follows: **What city is this?” “New York.” *“Do you like to come to town?” A vigorous affirmative nod of the head was the answer. **What do you do in the city?” — ~ “Whom do you visit?” “Nice people.” When the general laughter subsided, the animal was given sums to do. added and subtracted rows of five figures unhesitatingly and without a mistake! The clever pony was Black Bear, §

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TT, wre ww es of ason, olves , and vents idence of 1 intelli. yeen men He gave Te added lare-root her this ot. The he head ubsided, do. He e figures stake! Bear, a February, 1929 Shetland, whose feats have aroused wide- spread scientific interest. He was “dis- covered” by W. W. Fuller, a tobacco magnate, some. months ago. At that time the pony, in charge of his owner, a Mr. Barrett, a venerable wanderer who might be called the American counter- art of Trader Horn, came to Mr. Fuller’s estate near Briarcliff, N. Y. Both Black Bear and his quaint old master have been guests there ever since. UT to return to the demonstration at Sir Joseph’s. After Black Bear had shown that he was no mean mathematician, t he “interview” was re- sumed, thus: “Black Bear, were you ever in another 9” Again the affirma- tive nod. “Whose body?” You could hear a pin drop in the room as the pony reached for the tabs: His reply was: “King Solomon.” A gasp of astonish- ment from the guests. “When did King Solomon live?” “B.C. Long time ago.” “When were you born?” “February 25, 1917.” The conversation was interrupted once more, this time by Mr. Barrett, who showed the pony a small clock and asked him to tell the gathering what time it was. Deliberately, Black Bear picked out the figures, ‘‘ Nine twen- ty-eight.” “How many min- utes to ten?” “Thirty-two.” “When did Co- lumbus discover America?” 1492.” At this point, the pony made the only mistake of the eve- ning. Asked to give the date of the Dec- laration of Independ- ence, his answer was, “July 4, 1775.” “Bless his heart,” said one of the women. ‘“‘Perhaps he’s tired.” “Not at all,” explained Mr. Bar- rett; “that was just a slip of the tongue!” XT? Black Bear was told to “go kiss the lady in the pink gown.” There were five women in the room. Without a moment’s hesitation, the pony walked to the wearer of the dress of the color indi- cated and “kissed” her. Now came the final question. “Black Bear, tell us where you get all your knowledge?”’. POPULAR SCIENCE MONTHLY And the pony spelled out: “‘G-o-d”! Sir Joseph’s friends looked at each other in mute amazement. Then Mr. Barrett casually remarked that the pony could solve square-root and cube-root prob- lems! And so, for another half hour, the marvelous animal found a number of solutions quickly and correctly enough to An inventor among the apes. With his trapeze bar, Dohong, the orang-utan, devised a lever with which he broke horizontal bars. make many a college student jealous. Black Bear’s astonishing performance came as the climax to a series of demon- strations of animal intelligence that have engaged the attention of scientists of late. Fellow, a remarkably bright six- year-old German shepherd dog, recently underwent a second psychological test at Columbia University, New York. Fellow has a “vocabulary” of about 400 words; that is, he thoroughly under- stands that number of terms. And he proves his ability by responding to com- mands, or rather requests, in which that many different words are used. The average person, psycholo- gists say, doesn’t use more than about 350 words in his conver- sation! S° FINE are Fellow’s powers of perception that he can dis- tinguish between the letters of the alphabet, and so knows the difference in meaning between words of closely similar sound. The Columbia psychologists placed a silver dollar and a linen collar beside each other on the floor. “Fellow,” asked Jacob Her- bert, of Detroit, his owner, “will you bring us the collar?” The dog leaped forward and retrieved the desired object. **Fine,’’ said Herbert. “‘Now put back the collar and give me the dollar.” And Fellow promptly replaced the collar and brought the silver coin! The dog knows the difference between right and Rex, the wonder horse of the movies, is one of the most temperamental stars of Hollywood. He actually selects his own casts for his pictures. At the left is Fellow, the remarkable German shepherd dog, passing intelligence tests. He knows 400 words. In circle, Rin-Tin-Tin, the famous shepherd dog star of the movies. left better than some Army rookies, and distinguishes between men and women, adults and children. One of Fellow’s accomplishments par- ticularly impressed the New York psy- chologists. Herbert asked one of the men to take the dog firmly by the collar. . ‘Now, Fellow,” he said, pointing to the secretary of one of the professors, “I want you to protect that young lady; don’t let anybody touch her.” The slightest move in her direction brought angry growls. Then, as Herbert himself walked over to the girl and started to touch her, even he was treated to bared | fangsandthreat- (Continued on page 146)

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ae 26 Prospecting for Gold POPULAR SCIENCE MONTHLY With Electricity Amazing Instruments Find Hidden Ores and Bring New Romances to the West ROSPECTING by electricity is here. The new method, which the U. S. Bureau of Mines’ experts have just tried out in Colorado, discovers underground veins of metal without digging an ounce of earth. There is no need to drill costly “test shafts” where someone thinks there is metal. A few electric connections, and valuable deposits of iron and copper ore, the ex- perimenters found, write their location on prospectors’ maps. So portable is the apparatus used that it may be carried on the backs of a prospecting party and used to survey great areas for possible mineral stores. Meanwhile, within the last few months, other fascinating ways of locating underground mineral riches have been devel- oped. Prospecting for oil with earthquake shocks, produced by blasts of dynamite and recorded on seismographs or earthquake- detectors, has passed its ex- perimental stage and is now in use by several great oil com- panies. Radio instruments are said to detect gold and silver hidden in the earth. Another method, which makes metal ores reveal themselves through magnetism, has been tried out successfully by the Bureau of Mines. Will participants in the next great gold rush be technical men armed with electric apparatus—figures that look more like telephone linesmen than prospectors? Yo picture electrical prospecting in action, imagine the strange scene at Cari- | sa 4 By GEORGE The “ Pittsburgh Coil” devised by Bureau of Mines experts to prospect for buried ore. Like a radio direction finder, it can be turned and tilted in any direction. When no hum is heard in the headphones, direction of coil indicates position of ore. LEE DOWD, Jr. bou Mountain, near Nederland, Colo., where the Bureau of Mines experimenters tried out their apparatus. On a grassy knoll a signaler sits at the key of an Army field telegraph outfit. Two bare copper wires, connected to it, have been laid in How hidden veins of ore are mapped by telegraph dot-and-dash signals sent through the ground. The electric current carrying the signals follows the winding course of the underground ore deposits. parallel lines 500 feet apart along the stubble and rocks of the mountain—and pegged to the earth, every hundred feet, with metal stakes for electric contacts. As the telegrapher presses a key, a pre- arranged signal—three dots and a dash— flashes along the wires and into the earth. With headphones on his ears and a rub- ber boot on one leg, a man is seen strolling about, seemingly aimlessly, a few hundred feet away. He carries a trailing wire tethered at one end with a ground stake. Wound about the rubber boot is a bare wire of copper that he grinds into the earth at each step. Actually he is listening intently to a three-dot-and- dash signal he is receiving in the headphones from the earth. Sometimes it grows louder as he walks; now, fainter. It has stopped altogether. He halts, and marks the spot upon the ground. That is a “‘silence point” that will be used to map the precious ore. By these “‘silence spots” he can tell exactly what path electric currents take as they course through the Two types of direction-finding coils for lo- cating ore deposits. At lower left is an am- plifier to increase strength of the signals sent through: ground and heard in headphones, earth from one of the parallel, pegged. down wires to the other. And the electric currents follow the ore! Hidden ore deposits are better con. ductors of electricity than the rock and earth that surround them. In that fact lies the whole secret of electrical prospecting. As expected by Dr. A. S. Eve and Dr. D. A Keyes, who headed the explor. ing party, charts plotted from the headphone man’s findings showed that the underground electric currents traveled in crooked, curving paths from one wire to the other. From these charts they mapped the probable location of an ore body that would play such tricks upon an electric current, HEN they compared the mythical ore body on their map with an actual deposit of magnetite, a rich iron ore, which a laboriously executed map of the U. S. Geologic Survey showed to exist in that locality. The two maps agreed exactly upon its location. In a few hours’ time the Bureau of Mines experts, with- out even scratching the surface of the soil, had charted a vein of iron ore that the U. S. Geologic Survey had taken months to map. The same electrical apparatus will de- tect gold, silver, copper, or practically any metallic ore that is a good conductor of electricity. Copper was located in another electrical test at Ward, Colo., a few miles from the scene of the other experiments. Also, the prospectors found that certain sulphide ores of copper and iron—and there are other sulphide ores of more precious metals—are themselves natural storage batteries, generating faint underground currents that lead to their detection. HE experimenters tried a half-dozen varied “hook-up” methods before they left Colorado. A “Pittsburgh coil” and a “leapfrog method” of electric ore- detecting were two novel developments. The Pittsburgh coil, a sort of square looped aerial of their own invention, re- placed the man with the headphones. It was*not connected to the earth, but was swung about like (Continued on page 133)

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ary, 1929 or lo- | aM. | sent ones, egged. lectrie Tr 6con- e rock n. In ret of rected D. A xplor- | from dings round ed in from From d the n ore such rrent, 1 the their sit of ore, of the ist in greed ours” with- f the that aken ll de- cally uctor ‘d in lo., a other ound and ores elves ating id to ozen ofore -oil” its. uare , Te- 133) February, 1929 # e iquetied FEW weeks ago the little Navy blimp J-3, descending to its hangar at the Lakehurst, N. J., air station, ran afoul a weather vane. With a ripping noise her gas cells parted, and 25,000 cubic feet of helium gas disappeared to wander about among the elements, perhaps for ages before being captured and put to work again. ; Only ten years ago that little mishap would have cost the Navy approximate- ly thirty-six million dollars. In fact, helium then, little known outside the lab- oratory, was so rare as to be virtually priceless. All lighter- than-air craft — German, British, French, Italian, and American—were filled with the highly inflammable hydrogen gas. Yet today the loose change in your pocket might buy a barrel of helium, a cubic foot costing only about three cents. For within the last few years new fields of natural gas, from which come high percentages of helium, have been discovered and new and cheaper methods of extract- ing it have been developed. It is said, for example, that the new plant near Amarillo, Texas, in which the Govern- ment is at the present time installing machinery, can sup- ply the entire needs of the United States for many years to come. Pees s ND the United States is the only nation having, considerable quantity of he- lium. It is an all-American product. Practically the world’s entire supply—which is to say, the United States’, for its export is forbidden by law, as an American firm found out when a Canadian University and a Czecho- Slovakian scientist wanted supplies—comes from the so far as anyone knows, any H= is told the story of the Helium B and. "Freezes Part of Uncle Sam’s helium laboratory in Texas, where experiments have developed new and cheaper methods of extracting this valuable gas. strangest gas in the world. First found in the sun and used mostly to inflate airships, it is now proving valuable in radio, deep-sea diving, lighting systems, metallurgy, medicine, and for toilet preparations. Its price, once prohibitive, has been reduced to almost nothing. Mr. Stuart tells how, in a few years, scientific experiment and discovery have brought an almost priceless rarity intoeveryday uses for mankind. POPULAR SCIENCE MONTHLY ME 2s _ p aaee 5 — 4 a Cee ee ye a OeGS ee ge Steg Sag ete saat as Le OR ee Lee. Only America has enough helium to inflate its airships with the noninflammable gas. natural gases of Texas, Oklahoma, and - Kansas. Helium, named from the Greek word “helios,” meaning “‘the sun,” is a color- less, odorless, tasteless noninflammable gas with about 92.5 per cent of the lifting capacity of hydrogen, the lightest gas known. It was first discovered in the sun by means of the spectroscope, in 1868, and discovered on the earth, in supposedly infinitesimal quantities, in 1895. Because of its lightness and non- inflammability, its chief use has been to vod : hs erate fill the gasbags of balloons and airships. A dirigible filled with it cannot be shot down in flames, nor is there danger of a disastrous explosion set off by motor exhaust, ignition sparks, or a carelessly lighted match, as is the case with a hydrogen-filled airship. Some appalling examples of this danger are very well known. HEN the giant dirigible Graf Zep- pelin made its recent flight from Germany to the United States, smoking was forbidden. No food was cooked. Precautions were taken even against the flashing of a tiny spark from a tack in the heel of a passenger’s shoe by contact with metal in the ship’s deck. At the Lake- hurst, N. J., landing field every spectator was handed a printed request not to smoke, even in the open air. The huge silk, rubber, and metal sausage was filled with hydro- gen, probably the most highly inflammable substance known. A _ chance spark might have caused a great catastrophe. Meanwhile the Los Angeles, pride of the Navy, nestled safely in its sw * Below: Hundreds of small cylinders of helium waiting shipment. It took 13,000 of these to fill the Shenandoah at her first inflation. — ———— ios

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r nares ates Aeneas a mt (AA AA A RSENS Ons rc hangar—its gasbag filled with fireproof helium. ] ESIDES the inflation of airships, within the last year or two, other uses for helium have come to light. Helium, it has been found, will- prevent the “bends” or caisson disease that affects deep-sea divers. It is used in metallurgy, fills radio tubes and glow lamps, and finds a place in nautical and other scientific instruments. It cools electric trans- formers and high-speed generators. It is an important aid in chemical drying plants, and assists in the manufacture of cold cream and shaving soap. Helium is the least soluble of all gases in water or other liquids—a marked contrast, for instance, to the carbon- dioxide “fizz” of charged water. It is this property that makes it a boon to deep- sea divers. The excessively painful cramps or “bends” felt by a diver emerging too suddenly are believed due to bubbles of nitrogen gas, nor- mally a part of the air, which are forced into his blood un- der high pressure and cause acute distress when they froth out as he reaches the surface. Since helium will not dissolve in the blood, an oxygen- helium mixture is supplied to the diver instead of air, and experiments indicate that the menace of the “bends”’ is ended. Helium is insoluble, too, in molten metals, a fact that makes it a valued tool of metallurgy. Helium, although lighter than air, is stickier. This peculiarity makes it ideal for filling the interior of nautical and other scientific instruments. In these, delicately balanced parts seem to swing interminably before they slow sufficiently for readings to be taken. An atmosphere of helium instead of air “dampens” the vibrations and makes reading easy. ADIO tubes and glow tubes such as are used in television are filled with helium gas, in the first instance because of its usefulness in permitting electrical current to pass in one direction only, and in the second, because of the brilliant glow produced by an electrified tube filled with low pressure helium. This glow is not unlike that of neon, whose scarlet light is familiar in advertising POPULAR SCIENCE MONTHLY signs; but where neon gas gives a red light, that of helium is a soft yellowish- white. Heliiim conducts heat six times as well as air; you would shiver if you were sur- rounded by helium, for the gas, permeat- ing your clothes, would draw off your body’s warmth in no time. Moreover, it has a high specific heat, which means b Newly designed helium tank car, consisting of three tanks forty feet long and five feet in diameter, containing helium under pressure. Twelve of these carloads will fill the Los Angeles. that it can absorb much warmth without itself rising appreciably in temperature. These facts, coupled with the advantage that it is a poor conductor of electricity and therefore proof against short cir- cuits, make it an excellent cooling blanket for high-speed dynamos, and a safe sub- stitute for oil as a contact breaker in transformers. RYING operations are sped by the use of helium. Although it is not yet practicable to hang up your wash to dry in a tank of helium gas, the clothes would come out moisture-free in double- quick time. The reason is that water and other solvents evaporate much more speedily in helium than in air. Prac- tically this is important in chemical fac- tories, where trays of chemicals are efficiently dried under air-free hoods con- taining helium. In the manufacture of toilet prepara- tions, such as shaving soaps and cold cream, helium recently has proved valu- able because of its insolubility, already mentioned. Soaps and pastes are mixed Design for the two huge dirigibles, largest in the world, to be built for the U. S. Navy. Each will have more than twice the helium gas capacity of the Los Angeles. In the drawing the envelope is broken away, revealing complete hangar for airplanes within, capable of housing five scouting planes. All engines will be housed in the hull, eliminating the external cars. At the left is a crogs- section view of the hull construction, showing runways circling the interior, with air excluded, through the presence of helium. The gas has other queer characteristics, which some day may be put to work Chilled until it changes from a gas tog liquid, for instance, helium is the coldest known fluid. It liquefies at about 450 degrees F. below zero, and has been chilled by Prof. Kamerlingh Onnes, at Leiden, Holland, to the coldest temperature ever produced by man—457 degrees below zero, or within two degrees of that “absolute zero” that physicists call the rock bottom of the temperature scale. Some of this super-chilled helium, dropped in the mid dle of the south polar ice sheet for which Commander Byrd and his exploring party are heading, would boil like water on a red-hot stove. At its temperature a tin cup be comes brittle as glass, and mercury freezes‘ so solidly that you could make it intos hammer head that would drive a nail. Only by im mersing other substances in liquid helium can they be made as cold; no other sub stance has its chilling power, LONELY stranger is he lium among the chem- ical elements, and only once has it been suspected of en- tering into combination with one of them. Prof. Karl T. Compton, of Princeton University, has reported that it will combine with mercury in a vacuum tube, when the mercury has been rendered active by invisible ultra-violet light. Perhaps these properties will suggest new uses in time. One thing is certain— that none of them will equal in novelty some of the entertaining suggestions that have been received by the trade research department of a commercial helium com- pany of Dexter, Kansas. A St. Louis in- ventive genius had an idea for a crash- less airplane. If the motor failed, a tank of highly compressed helium on the under side of the fuselage was to support it in the air—only it wouldn't. Next came a man with a talent for advertising. He proposed to make and sell gaudy painted windmills, whose whirling blades were to attract attention to the advertising placard they bore. The only trouble was that the wheel bearings had a way of wearing out. Wouldn’t a little tank of helium—about the size and shape of @ quart mason jar, he suggested—suspend the windmill (Continued on page 130)

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POPULAR SCIENCE MONTHLY CANIS . MAJOR i * * F thal # x AQUILA CENTER OF OUR UNIVERSE PLACED e BY DR.SHAPLEY * 47,000 LIGHT YEARS\, » \FROM EARTH IN : THIS DIRECTIONy > . . e SAGITTARIUS & s i* ee . « iat et? * ° CORONA AUSTRALIS . Ke a): a : , TELESCOPIUM LEGEND BO 1ST MAGNITUDE x 2ND * =" + 4TH e dl ra BOOTES ® HERCULES . os CORONA * BOREALIS ™ 2 a. = a w > x ally SERPENS . OPHIUCHUS * scor®io +* one mT ANTARES CANES VEN He ae * 7 . . *cOMA ,BERENICES NEW LOCATION OF BRUCE TELESCOPE AT BLOEMFONTEIN SOUTH AFRICA PAPER {EIGHT

A New Guide to the Heavens MAGINE a giant disk wheel whirling in space. That is our universe as astronomers now picture it. Dr. Har- low Shapley, director of the Harvard College Observatory, Cambridge, Mass., has just announced that, 47,000 light years distant in the direction of the con- stellation Sagittarius, he has discovered the central hub about which it spins. This hub he estimates to be 29,000 light years across and 16,000 light years thick. A light year, the distance a beam of light will travel in a year, is about six trillion miles. For his measurements, Dr. Shapley used as a yardstick the Ceph- eus variable stars—‘‘winking stars” whose changes in brightness permit com- plicated astronomical calculations of their distance from the earth. Dr. Shapley also reports the discovery of 8,000 spiral nebulae, each believed to be a universe like ours, revealed by photo- graphs made at the Harvard Observatory in Peru. The total number of these “island universes” is estimated by Dr. Edwin Hubble, of Mt. Wilson Observa- tory in California, at ten million; some- where in space, astronomers believe, is @ center of centers about which they spin. Above our artist has charted the im- portant stars and groups of stars in our universe. You'll find the drawing un- usually helpful in identifying the stars. sie een een ona asi ta mr nna mre americana nsec ena scone ace sen were

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POPULAR SCIENCE MONTHLY

February, 1929 3 QO 5!—A Challenge to Science

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© 1928, Pacific and Atianttc Photos, Inc. A tragic scene on the careening deck of the Vestris _ just before she sank—Inexperienced seamen, wearing ie life belts, struggle frantically tolaunch theship’s boats. FTER every great sea disaster humanity searches for devices and regulations that will pre- vent the recurrence of such horrors. The Lamport & Holt liner Vestris sank two months ago off the Virginia Capes with a loss of 111 lives. She lies on the floor of the Gulf Stream two miles below the surface white caps. As a result of searching investigation into this disaster it becomes apparent that if similar tragedies are to be prevented in the future, it will be because of the progress of science and the achievement of invention. Old, outmoded life saving equipment must be discarded or im- proved; new contrivances created and perfected. A new type of lifeboat, recently ex- hibited and tested in London, for example, might have saved some of those lost in the lV’ estris tragedy. This craft, reversible, self-emptying and unsinkable, is some- what similar in appearance to the ordi- nary lifeboat. But a cross-section re- sembles a shallow letter “H’’ and the upper and lower portions are identical in construction. Thus, the boat is still a boat when it upsets! In addition, it is made self-emptying by a system of non- return valves that operate no matter what. side happens to be uppermost. Sealed airtanks give it buoyancy and keep the deck-level always above the water line. In tests at fhe London docks, one of ELPLESS women and children jp battered lifeboats, dangling at the. steel side of a sinking ship, doomed to be swallowed in the sea! after the investigations that followed the tragedy, has not been stirred by the verdict of marine experts that “it could have beep Here is told how inventors are answering the Vestris challenge, Who, By FREDERICK TISDALE

Our artist here pictures the difficulty of launching lifeboats from the high side of a heavily listing vessel. The descending boat must scrape against steel plates of the steamer’s hull, chancing breakage or upsetting, with loss of life. the boats, capable of holding sixty people, was loaded with 180 sandbags to represent their weight. First, the non- return valves were stopped up and three tons of water pumped into the boat. The gunwale remained well above water level. Then the valves were released and the vessel emptied itself in a little over one minute! To simulate lurching in a stormy sea, the sandbags were trans- ferred, one by one, across the boat until one side was light and the other fully loaded. Still, the gunwale remained above water. An ordinary lifeboat, put to the same test, began to sink after the seventh sandbag had been carried across! VEN such boats, however, would not solve entirely the problem of safety at sea. One of the greatest difficulties lies in the launching of |lifeboats in the hour of peril. The trouble is that many seamen no longer are sailors. In the good old days of the clipper ships—of “‘wooden ships and iron men’”’— crews consisted of fellows who were past masters in handling ropes, oars and tackle. But modern steamers are really intricate collections of marvelous ma- chinery, and the men who work them, many of them sea-going hotel men, have no need, under ordinary conditions, of skill in seamanship. And difficulties in the lowering of lifeboats today are in- tensified by the fact that the deck of a passenger vessel may be sixty feet above the water—the height of a six-story building! HE fact that few women and no children were rescued from the Vestris testifies to the failure of life saving equipment. Pictures, raw and vivid, leap out of the tales told by sur- vivors, emphasizing the defeat of me- chanics and sailors by the deadly force of the ocean. A fireman, Boxill, testified that he took his station in a lifeboat filled with pas- sengers. The boat was lowered part of the way—and stuck. He and another meniber of the crew stood with drawn knives waiting for the order to cut the gear and release the boats. The Vestris rolled over while the boat swung in mid- air, spilling the passengers into the water. JBoxill swam to a piece of wreckage. “There were some dead children and women around there, sir, and that got me kind of dizzy. I . . . swam off.” Charles W. Johnston, a passenger, saw two boats hanging to the ship, loaded with women and children, when she

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TY, 1929 mn Poe med ‘ho, een [ors ge. in- fa ve February, 1929 went down. A member of the crew said that a boat stuck on the side of the Vestris instead of sliding into the water. Two members of the crew cut away the ropes with knives, but the line at one end parted first “and emptied everybody into the water.” Another struck something and was launched with a hole in her side. HE sad inventory of these boats illus- trates one great difficulty encountered in a sinking ship. Rarely do stricken yessels go down on an even keel. They list—or lean—either to one side or the other. This lifts the high edge of the boat deck away from the water and places the side of the ship below the lifeboat. When the lifeboat is lowered it must scrape the parent vessel’s hull as it descends and this hull is a series of irregularities where the steel sheets overlap, and where rows of rivet heads protrude. On the other hand, the list places the opposite side of the deck nearer the water and makes it easier to lower the boats there since the drop is unobstructed. The Vestris had a star- board list. In landlubber English, that means she leaned to the right. This brought the starboard boats close to the water and lifted the port or left side boats high in the air, placing the ship’s hull below them. It was in the lowering of the port boats that the disaster struck most heavily. But science and invention have begun to solve the problem of lowering boats quickly in emergency. The latest and finest devices for handling lifeboats are to be found on the new steamships of at least one line operating from New York. Small electric winches lower and raise the boats. An equalization device keeps the small craft on an even keel as they drop toward sea-level. NE of the loudest public outcries usually heard following shipwrecks is to the effect that the wooden lifeboats leaked. And in that connection the owners are accused of culpable thrift. Such complaints are due to a popular fallacy. As a matter of fact, a wooden boat is more expensive than one of steel. A new safety substitute for the usual heavy, awkward wooden hatch cover. This hinged cover of light, strong metal, can be closed quickly and easily if a storm rises. POPULAR SCIENCE MONTHLY In addition, certain countries, Great Britain among them, require the use of wooden boats. Why? Because experts agree that they are bet- ter. The best materials are spruce and pine. The finest type is clinker built,that is, from planks that overlap each other. The objection to metal boats is that they are not as strong. Any : smashing or denting VES GYROS WHEN SHIP BEGINS WH ROLL upsets their equilibrium and when punc- tured they are hard to repair. Rafts are another form of safety equip- ment upon which inventors are concen- trating. Many important passenger ships today carry one or more liferafts made of balsa, the lightest of all woods. The balsa tree, which grows in the mountains of Bolivia around the shores of Lake Titicaca, is lighter than cork. Radio fans have become familiar with its wood, which has been used in making loud speakers. One or two liferafts of balsa wood might have helped save some of the ._ women and children of the V estris. The best type of liferaft, marine authorities agree, is the catamaran. It is kept afloat by two long pointed air-filled metal cylinders. Be- tween these is a wooden plat- form for the passengers. The finest have copper cylinders, to prevent rusting, and they are divided into compartments so that, if one section is dam- aged, enough air remains in the others to keep the craft afloat. There are rowlocks for 3 iN RIGHT DIRECTION Latest device for launching lifeboats. Mechanical arms swing wel out over the side . and a few naval craft are so ani eep the at on ° even keel as it is low- equipped. ered by powerful electric winches. 31 Science’s answer to the problem of preventing serious lists such as proved the Vestris’ undoing. The whirling flywheel of this stabilizing gyroscope will bring a ship back on an even keel, even if the cargo shifts. propulsion and steering. The tops and bottoms are alike, as in the case of the lifeboat, de- scribed above, so that it makes no difference how the raft strikes the water. Science, too, already has answered the question: How is it possible to prevent lists such as proved the Vestris’ undoing? Some day, I believe, every ship carrying passengers will be equipped with stabil- izing devices which will keep her on an even keel and bring her back even if her cargo shifts. Already many yachts The gyroscopic stabilizer is the device that does the trick. A gyroscope is a flywheel mounted so that it is free to revolve in any direction. Make it big enough, heavy enough in the rim and it will resistevery effort to tip itout of its orig- inal plane of rotation. Some large yachts that have stabilizers ride with decks as level as a ballroom floor through storms which would set the greatest liners rolling. One Japanese cruiser was brought from a thirty-degree roll to an even keel in a few seconds by means of the gyroscope. IFE-BELTS of a type far superior to the standard “vest” type many pas- senger boats are still carrying, and which were carried by the Vestris, now are available. This type of belt makes it almost impossible for the wearer’s head to be submerged. One may go to sleep in the water without danger of drowning, while with the ordinary life-belt constant effort and wakefulness are necessary. Meantime marine engineers and archi- tects of all seafaring nations consider the perfecting of the unsinkable vessel their greatest and most pressing problem. When this goal is reached and inclusion of the latest safety-devices in ships’ equipment is compulsory, science and in- vention will have accomplished their purpose of relegating ocean disasters to the past.

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2 If You Had Millions to Spend— HAT would youdo? Harry Guggenheim chose togo in foraviation. He marshalled the forces ~ of science to conquer the flyer’s deadliest foes, and to make airplanes as safe and useful as automobiles. Here is the story of a twentieth-cen- tury pioneer, a man who looked into the future, It forms a stirring episode in the drama of the air, Two fiying laboratories of the Guggen- heim Fund, piloted by veterans, carry on experiments to conquer fog on airways. FEW weeks ago a new research laboratory was added to the world’s gallery of modern scien- / tific developments. > It is a laboratory without test tubes, retorts, microscopes, and Bun- sen burners, and without learned looking men using these intriguing paraphernalia for purposes of minute investigation. This new “research bureau” hurtles through space. It consists of two air- planes. The “professors” in charge are experienced aviators. And its aim is the ultimate defeat of the flyer’s most dan- gerous enemy—fog! Equipped with a wealth of instruments, the unique flying laboratory conducts its experiments on a section of an established airway in the East. Here a thorough study of fog flying is made under regular operating conditions. Hope runs high that, as a result of this practical pioneering work, the airman’s worst foe will be beaten to a standstill at last. The flying laboratory was conceived and established by the Daniel Guggen- heim Fund for the Promotion of Aero- nautics. It is the latest in a series of valuable contributions toward the prog- ress of aviation made by the organization which is probably doing more than any other agency to hasten the day when all the world will be on wings. HE Fund has set itself the task of making aviation safe for humanity and humanity receptive to the benefits of aviation. This program it carries out in a thoroughly practical way. It has en- dowed special schools of aeronautics in some of our leading colleges and universi- ties. It planned and financed Lindbergh’s celebrated nation-wide tour. It conducts experiment and research activities. It POPULAR SCIENCE MONTHLY ra By MICHEL MOK organizes international movements de- signed to promote the safety of flying. Just now it is engaged in a nation-wide campaign to have the towns and cities of the country identified by roof-marking for the guidance of the airman. In brief, all of its activities are directed toward the perfection of aircraft and toward the de- velopment of that attitude of public con- fidence toward aviation which has come to be known as “airmindedness.” Somebody once aptly said that every institution is but the lengthened shadow of a man. Eager to measure the stature of the personality behind an organization that is preparing a way through the clouds for you and me, I sought the head- quarters of the Guggenheim Fund. There, in an unostentatious office, un- encumbered by fancy-titled assistants, expensive furniture, or red tape, I found Harry F. Guggenheim, president of the Fund. Names often have a way of subtly suit- ing their bearers. The friendly informal- ity of this man’s first name fits him like a glove. About forty, blue-eyed, tanned of skin, well set up and proportioned, and the possessor of a ready, engaging smile, he is the kind of chap who is likable at first sight, because. he combines ;,. inherent dignity with ™ a deep-seated, genuine interest in his fellows that is betrayed in al- most every word and gesture. At once I understood how he must have ap- pealed to Lindbergh, his sworn friend, from the moment Guggen- heim, then a total stranger, shook his hand and wished him “Safe landing!” the day before he set out on his epic trans- Atlantic flight. In the course of our chat, I caught the color and outline of a strong, rich per- sonality, one that shapes dreams into deeds; that bridges the gap between the philosopher and the organizer, the scien- tist and financier. “The first word in aviation has hardly been spoken,” he told me; “but you and I will see the day when the average man, and woman, too, will fly with the same Daring pilots are trying to solve the prob- lem of overcoming perils of sleet storms which cover airplane wings with icy weight, February, 1929 comfort and safety they enjoy dri i around in their automobiles today.” There are many who share that visi ‘ and many more who still scoff at its meal mention. But this man gives without stint of his time and his talents to bring about a quick realization of the old dream” of breaking the ties that bind humanity” to earth! = ee SOON found out why. To Harry” Guggenheim, airplanes are the han” bingers of peace, the instrumentality that eventually will bring about a true and lasting sympathy among the nations: This underlying sentimental reason for his absorbing interest in aviation he ree vealed when I asked him what he com sidered the greatest single contribution the airplane had made to modern progresg, “Tts annihilation of space,” was hig quick reply, “and through that, its estab lishment of closer communion between various communities. At one time, nob so long ago, the populations of our East and West were practically two different peoples because of the distance that sepa rated them. They had their own customs, traditions, view- points, and aspira- tions. The railroad came and did much to improve that situation. The air- plane is doing and will do the rest! The next step will be the binding together of nations, with the thorough under- standing of each other’s ideals, needs, and problems that is bound to follow.” Curiously enough, Harry Guggenheim originally saw the potentialities of the airplane as a power- ful ally of peace and progress when a pilot during the World War. As a boy, he had spent one term at the Sheffield Scientific School at Yale and had worked in the mines and smelting plants of Mexico for the American Smelting and Refining Company, one of the concerns controlled by his father’s firm. Later he got the degrees of Bachelor and Master of Art¢ at Cambridge University in Eng- land. There he (Continued on page 162) February:

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POPULAR SCIENCE MONTHLY toms, riew- pira- lroad much that e air- and ! The ye the ier of the ider- each 1eeds, that low.” ough, rheim the f the ower- e and a 8 at the d had “I plants r g and - Harry F. Guggenheim, Godfather of Flight cerns er he aster : As President of the Daniel Guggenheim Fund for the Promotion of Aeronautics, he has taken the lead * 4 in making air travel safe for everyone. “‘The first word in aviation,” he says, “has hardly been spoken.”’ Eng- Z ; je 1 62) . Drawn fromlife espectally for POPULAR SCIENCE MONTHLY by B. J. Rosenmeyer_

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POPULAR SCIENCE MONTHLY

You hold your breath to see the hero, in his high-powered roadster, racing a motor cop. The scene is filmed with tiny model cars, standing still. A moving back drop gives the effect of high speed. Amazing how Making Movie Thrills 2 Sandow! The gear, of rubber, and the railroad tie, of light bal- sa wood, weigh only 7 pounds.

“de ~ On the screen it looks like a : A remarkably faithful model of the city of oure-enough ocean liner, tossed Detroit, used in a movie thriller. The figure by a real hurricane in mid- of the hero, superimposed, appears to do Atlantic. But in the studio ) breath-taking stunts atop a tall building. where the picture was made ‘ } the liner was a model ship ‘ obbing in a tank no larger — canteens It was rocked <P ; ' - Remember how Douglas Fairbanks rode and tossed about by a wave- = a the magic carpet through the air in The making mechanism operated / S Thief of Bagdad? Well, it wasn’t Doug by a small electric motor. at all. The riders were puppets, and the toy carpet was manipulated by wires. Left: Skilled toy makers of the movies, constructing a street of model stores and office buildings, smaller than doll houses. Pho- tographed at close range, they appear as real, full-sized buildings on the screen. By trick photography, the human figures and action of the drama are superimposed on this setting.

This miniature ship captain’s cabin, rocked by motors, seryes as the setting for an exciting mutiny in a storm. Depicted on the screen, the lurching room seems real enough, with action superimposed.

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Dry and safe in the camera chamber, Mrs. Williamson watches a native diver outside the window pluck a sea-fan of lacelike beauty. A prowling beast of the deep. This remarkable photo- graph of a shark hunting its prey along a coral reef was snapped by Williamson from the diving chamber. POPULAR SCIENCE MONTHLY ” It's long way down, and no elevator. Here Mrs. Williamson is entering the flexible steel tube that leads to the camera “studio” on the sea floor. Taking notes on the drama of the deep. Just beyond the heavy glass window is a frolicking school of curious “sergeant- major”’ fish, so-called because of their stripes of black and gold. Ringside Seats on the Ocean Bottom VICIOUS shark prowls along the sea bottom hunting for prey. Stealthily on his trail glides a mon- ster sucker fish, bent on attaching him- self like a parasite to the undersea de- stroyer. This and other thrilling dramas of the deep are revealed in remarkable photographs snapped recently at the sea bottom off the Bahamas by J. E. Wil- liamson, pioneer undersea photographer, and Mrs. Williamson. Their camera studio at the ocean’s cel- lar is a globe-shaped steel chamber fitted with a window of massive glass. It hangs from a cruising ship by a flexible, hollow shaft of steel that stretches like an accordion to form a veritable “hole in the sea.” This weird contrivance was invented years ago by Charles Williamson, father - of the photographer, for deep-sea salvage. The younger Williamson and his bride have adapted it as a movie studio, and as a chamber from which divers emerge to gather specimens of coral. How the deep- sea chamber works. Observers descend by lad- der through a steel tube, hung from the ship. The photographer and his wife in the cozy chamber. At the left is a water-tight door through which divers can pass. Note headphones. Right: Action photo of an un- usually large sucker fish that lives by attaching itself to a shark and snatching food away from its host.

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36 POPULAR SCIENCE MONTHLY February, 195 One Jump Ahead of Death! A thrilling sport for the sure-footed. Crossing a narrow ice ridge atop Mt. Robson in the- Canadian Rockies. A great playground for mountain climbers—the challenging peaks of Eige: and Jungfrau in Swiss Alps, Will he make it? This climber risks a flying leap across a 12-foot gap on the Matterhorn. biel i at > ss, +s ’ apr? 2% Would you like to be in his shoes? It takes a real athlete to cross a treacherous “chimney” in the wild Grison peaks of the Alps. Almost straight up! Roped together, Alpine climbers scale sheer walls of rock, struggling 9“ «/ for toe-hold on the mountain’s rugged face. In the game of tag with death, every mountain climber finds his reward in the thrill of reach- ing his goal at the tip- top after a perilous ascent. The view above shows a conqueror of one of the tower- ing pinnacles in the Swiss Alps, roped to a cx Acmaigpeteiseninuccisecosistanicg = SCSC«Setng cme enigfanpmnay mean a ptenan of bundiedn cf fat y “ “ z . into the dep of a ya ng crevice. ere two clim) torches to light their difficult way over the treacherous ice. stand at the brink, deciding whether to try the crossing. Febru

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Modern Cave City Cave dwellers, whose homes in the cliffs are equipped with electric- ity and other modern conveniences, form one of the strangest villages in the world, called Troo, on the benks of the Loire River, southern France. At the right is the main street of the village—a up the face of the cliff. It leads past the ent ances to homes carved from rock wall. Light Organ Paints Scenery Colorful symphonies played with light instead of sound; and canvases painted without pigment, are suggested by the invention of a new light organ, called *Clavilux.’”’ ‘One of its possibilities is the substitution of beautiful, chang- ing color forms for costly stage set- tings. Above is a dancer performing before a “‘ backdrop”’ of light projected from the instrument. At the right the inventor, Thomas Wilfred, is seen at the console of the new organ. POPULAR SCIENCE MONTHLY 37 Strange Sights Snapped By Our Camera Men Left: Interior of one of the up-to-date cavern homes of Troo, showing comfort- able furnishings and clean rock walls. Even here electricity serves the housewife. i This Dentist Had Courage Olga, the leopard, had a jumping toothache, and kept the other inmates of a Los Angeles zoo awake of nights. So her trainer, a young woman, took the beast to a courageous dentist, placed her in the chair, and held the ferocious jaws apart while the cavity was filled. Olga jumped only once, and never growled. | 1 | ! ’ ti ' - 9 omy MEMMBOEE “Doty Drives Rocket Motorcycle Speeding at thirty miles an hour over a board track, a motorless motorcycle propelled by rockets was tested recently at the Velodrome, New York City. It is said to have been the first American trial of rockets as a means of propulsion. The designer and driver of the cycle is Capt. George White, whose experi- ments in Florida with a wing-flapping flying machine were reported in Porpucar Science Montuiy. He used a bank of ten rockets, mounted to fire to the rear and produce a succession of recoils to drive the machine.

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38 POPULAR SCIENCE MONTHLY February, 197 Februs Inventions That Every Housewife Will Appreciate Whoever thought of handle on a pie pan? No ana an inventor-housewife, who burned a finger pulling one Of the a old-fashioned kind out of thy oven. Anyway, here it is—thy pie pan with a handle—the removes fear of dropping the pie or scorching the hands when the juicy crusted pastry is done, — 7 . owe > pte This new electric broiler is said to cook a three- pound steak in ten minutes, searing both sides at once. Place the steak in the meat grill, insert in the broiler, and close the doors. By the time you have'dressed for dinner it is cooked. The device plugs into the nearest wall socket. The heating element is removable for cleaning. peer Te ein » Fag 883EBE727 The straight front edge of this The inventor of this aluminum orange new aluminum ladle is designed juice extractor claims it gets the last A miniature thermometer built into the top ofa « not only to get more food out, drop. A turn of the handle completely new waffle iron saves the first waffle, according to but to scrape the pot clean. reams the fruit, and the seedless juice the maker. You can’t spoil any, because you simply It affords a wide contact with is poured into a glass without spilling. preheat the iron until the temperature is just right the bottom of the pan. At the —then go ahead and bake. A temperature chart opposite end is a handy hook. tells the right heat to use to get the best results. Push down with your finger on the cover of the novel pin holder shown below, and a pin hops out. No danger of pricking your finger, for the device pute pin in your hand head up. s 4 t p P a — ——_— The wavy ripples of this unusual frying fork are de- signed to prevent bacon and other meats from slip- Gas range and gas refrigerator are combined in a new ping off as they are removed from the pan. The fork space-saving outfit for the kitchen. Steps are saved by has sharp, tenacious points to aid further in handling | the convenience of storing food near the stove; and so the meats. Wide slots allow the grease to drain from effectively is the cooling chamber insulated from the the meats as they are lifted. A long handle with range, it is said, that no heat leaks through to melt the ice. a wooden grip keeps the hand away from hot fat.

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ruary, 193) POPULAR SCIENCE MONTHLY 39 pebruary. 1929 No at Set this novel egg-timing alarm clock for rife, who | E “soft,”’ ‘“‘medium,”’ or “‘hard,’’ and when ONE Of the A the eggs are done the word “‘boiled’’ it Of the flashes into view in the window. A bell it is~the 3 rings at same time as a reminding signal. dle—that 1g the pie when the Here are two electric household novelties—a percolator 18 done, that makes either tea or coffee, using special immersion heater, and a special grill for toasting sandwiches. Coffee is brewed with a coffee basket and percolator tube; for tea-making this is removed and a tea ball is hung from the top. The toaster has expanding hinges. Mate. : Two coil springs sup- ply churning motion to A new metal clip holds the glass percolator top from mix batter or whip falling off when you pour the coffee. The clip fits cream in the jar. Once over the knob of the glass, and is fastened in place started, the two springs by bending its flexible ends under the rim of the lid. continue the motion. Snag a ciotnesline around this wall hook, and the harder you pull the tighter it grips. The rust- proof holder is declared to be a positive remedy for sagging lines, and it eliminates bothersome knots. * Bathroom medicine cabinets built into the wall and hid by mirror doors are a recent home improvement. Here is the newest—one with a double-hinged mirror that can be swung to any angle for the best light, or flat st wall. Something new in holders for ” a — metal wool, used to scour pots, is the flexible rubber handle below. This single electrical ap- Bending back the sides exposes pliance makes the break- a safety-pin catch that is slipped fast toast and coffee both through the wool and hooked. at the same time. The od heating element for pot and toaster are in the base 4 of this new cooking device. The nonspill salt and ire de- pepper shakers at the n slip- right are useful for pic- e fork nics as well as at home. ndling A sliding guard keeps 1 from the contents where : with they belong, and is t fat. arranged to uncover either salt or pepper. - j ad

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Creator of the new safety mono- plane — Donald Hall, who also designed the fa- mous Spirit of St. Louis for Lindbergh. In recent tests, his new ship (above) “flew itself” for long stretches up the Pacific Coast. Pe Unusual features b are its large lift- Diy ing tail surface th and omission of ; the stabilizing fin before rudder. * Here's the latest view of the remarkable Slate all- metal dirigible, first of its kind, nearing completion in its hangar at Glendale, Calif. The ship, 212 feet long, has a shell of corrugated sheet duralumin. The upper picture shows ingenious elevator in which passengers are to be lowered from the hover- ing ship along a rope passing through center. POPULAR SCIENCE MONTHLY Left: Without touching controls, two pilots demonstrate remark- able stability of new safety monoplane. Note the unusual tail plane, and low main wing. Men and Ideas Setting the Pace In Aviation Captain Boykow, German inventor, with a new gyroscope device which, he claims, will prevent gusts and bumps from tipping a plane off an even keel, and enable a pilot to fly without touching controls, once he has gained altitude. Ocean flyers Chamberlin, Koehl, and Fitzmaurice are said to have tested planes using the device. The latest creation of German builders is this army observation balloon, which can be con- verted into a controllable airship by addition of motor, stabilizing planes, and rudder. Thus the big bag can move about, independent of the usual ropes to the ground. The upper picture shows the gondola of the balloon. Three blades, instead of two, whirl at the nose of a new Boeing bivlane recently tested by Erik Nelson, 1924 Army round-the-world flyer, to discover whether extra blade will increase speed and enable a plane to rise more quickly Climbing seven miles above McCook Field, Ohio, Captains St. Clair Streett (right) and Albert W. Stevens, U. S. Army altitude flyers, recently took photographs of the city of Dayton below. It was a record. They are shown at left with their equip ment, including heating apparatus in foreground.

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uary, 1929 this con- | at the cently Army , speed nickly. Ohio, rt W. y took was a equip- round. February, 1929 PHANTOM airplane designed for war use and said to be practically invisible in the air is nearing completion at Not- tingham, England. Recent tests showed the possibility of constructing such a plane, on which it would be im- ible for enemy gunners to train artil- lery, as reported not long ago in PopuLar ScreENCE MONTHLY. POPULAR SCIENCE MONTHLY points of land along the shore will inclose a body of smooth water nearly a mile long and half a mile wide—pleuty of room for seaplanes to land and to take off. Arriv- ing aviators and passengers will disem- bark on two floating platforms, provided in addition to mooring places for the planes. Flood lights and air beacons will be at expected to reduce motor noise. Sound- proof cabins with walls lined with balsam wood shavings are being used experi- mentally in Fokker planes, and the U. S. Bureau of Standards is trying out a similar cabin under the direction of Dr. Paul Heyl, in charge of sound experiments at the Bureau. The cabins would also stop propeller noise, a sound almost as loud as the motor. Now the British govern- ment is building the first of these war terrors. It is made entirely of “plass””—a material of secret composition which looks like glass, can be handled like metal, and will stop bullets. Even the pipes for gas, water, and oil are of this ma- terial. An observer seeing the machine on the ground would rub his eyes and imagine himself gifted with X-ray vision. He could see right through all parts but the motor, control stick, and wires, which are of conventional ma- terial. Against the sky, only a hum will betray the plane’s approach. More Records Smashed OTABLE airplane records marked the last month in aviation. An unofficial world’s record for speed went to Flight Lieut. D’Arcy Grieg, British pilot, who flew his supermarine Na- pier seaplane at an aver- age speed of 319.57 miles an hour off Calshot, Eng- land, in four consecutive dashes over a standard course. Since Grieg failed to exceed the previous mark by five miles an hour, Major Mario de Bernardi of Italy . still holds the official world’s record of 318.62 . miles an hour. oe What is believed to be an unofficial speed record for commercial transport planes was set by an American passenger craft, of the Western Air Express, which averaged 177 miles an hour on a 365-mile flight between Oakland and Los Angeles. The world’s altitude record for a plane carrying two men, it was recently dis- closed, belongs to the two U. S. Army flyers, Capts. St. Clair Streett and Capt. A. W. Stevens, who recently climbed to 87,854 feet—within 600 feet of the world’s free-for-all airplane altitude mark—to take air pictures. A French flyer, Pierre Moigne, went after the altitude mark the other day and narrowly missed death when he fell six miles out of control. He landed safely but without the record. A Great Seaplane Harbor OON Montreal, Canada, is to have one of the finest seaplane harbors in the world. Two 300-foot breakwaters built out into the St. Lawrence river from TRANGEST of New Fighting Planes Is an Unseen “Ghost” of the Air— Other Astonishing Inventions and Records Mark the Month’s Progress in F lying Here is one of two huge semicircular batteries of searchlights which turn night into day for flyers landing at the new Newark, N. J., municipal airport. In all there are twenty-two of the floodlighting lamps, each of a million candlepower. installed for night flying. Visitors will see customs and immigration buildings, as well as restaurants and waiting rooms. The project has been approved by the Montreal Harbor Commission and the Department of National Defense. Silencing Roar of Planes URNING the roar of a 200-horse- power air-cooled motor into a mere hiss is the feat claimed for a new silencér developed by the makers of Fairchild planes. The invention, perfected with the aid of the Maxim Silencer Company, is a six-foot pipe as thick as a forefinger, which runs from the motor back under the cabin. It contains a metal spiral which is said to break up the sound waves without reducing power. Other devices have recently been demonstrated to quiet airplanes without stealing power or adding to fire hazard. The U.S. Navy is experimenting with an apparatus that passes exhaust gases through the vacuum of the propeller’s stream, and the changed rate of flow is First to Fly in Antarctic HILE Commander Byrd and his scien- tific expedition were sail- ing toward the Antarctic, a famous explorer already there scooped away the honor of being the first man to fly a plane over the south polar region. Sir George Hubert Wil- kins, who recently arrived at his base on Deception Island, Antarctica, an- nounced that he had al- ready piloted one of his Lockheed planes on a short flight in preparation for his projected air trip along the coast of Graham Land. He hopes to find a possible site beyond the Ross Sea ice barrier for a polar meteorological sta- tion. Planes Wear Life Buoys AND planes can leave the deck of an air- plane carrier for a shore visit when the sea is too rough to launch a sea- plane. But should the land craft fall into the sea the plane may be lost and its crew drowned. So the Navy recently has adopted a _ unique “flotation gear” to turn a land plane into a seaplane in an emergency. Two built-in compart- ments in the nose of the plane, and one in the rear, house barrel-shaped bags of gas-proof fabric, normally folded. But when a forced descent on water is made, the pilot pulls a lever that instantaneously inflates the three bags like bailoons, from a steel bottle that contains compressed gas. With these balloonlike pontoons, a plane can float indefinitely. A recent improvement in the device inflates the bags automatically, should the plane touch water. The entire equip- ment for a large bombing plane weighs only seventy pounds. New Gun Sprays Bullets PRAYING bullets from a machine gun, just as water is sprayed from a lawn sprinkler, is the purpose of a unique invention under consideration by the War Department for use in ting planes. According to the inventor, Joseph F. Butler, of Pittsburgh, it makes it unnecessary to aim a machine gun accue rately; no hostile (Continued on page 132)

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POPULAR SCIENCE MONTHLY voce agemeeegrs ot ~ Fee Ce RTE RR oe etm pret ot pe j ; j i ; j athers of Flig Wilbur and Katharine Wright flying before King Edward VII of England at Pau, France, in 1909. The King is at right of derrick. In foreground, fac- Little did the Wright boys dream that injuries to Wilbur in an ice “‘shinny”’ game would lead to world triumphs, ing the camera, is Orville Wright. “ HEAR the Wright boys are going camping this summer,” said a citizen of Dayton, Ohio, to a neighbor in the year 1900. ° “That so? Making money out of their bicycle business, I guess. Where are they going?” “Queer place called Kitty Hawk, down in North Carolina.” How Two Untutored Bicycle Men Conquered the Air After Learned Experts Had Failed—The Amazing Story of Wilbur and Orville Wright, Told for the First Time in Intimate Detail By JOHN R. McMAHON periment to create this, their first man- size model of the future airplane, and to test it for the first time in the air. They were humble beginners. They little dreamed that within three years at Kitty Hawk they would become the world’s first navigators of the air and that in result of such achievement “Why do you suppose they ff want to go that far?” “I wonder myself. Wilbur went into a store yesterday and bought a lot of sateen cloth—twenty-five |) _ yards of it. Girl says, ‘What do f you want it for?’ He says, ‘Well, I want it.’ ”’ “By George, I know! Those Wright boys are real original. They want to start a hunting and fishing camp — charge people money to belong—and that there cloth is to saaeceemetaaaseeneenmraemmeeen they would be received as hon- ored guests. by Pann ; the rulers of five Tet nations in Europe and the president of their own land. They make tents and beds.” “That’s it,” agreed the other. Maybe it was just as well the gossipers did not suspect that the cloth was required for wings on a flying contraption or man-carrying glider which the Wrights were to try out late that sum- mer at Kitty Hawk. It had taken Wilbur and Orville four years of pondering and minor ex- Wilbur, age thirteen (top), and Orville, age eight. Building their own printing press and working with tools gave them invaluable train- ing for inventive work. little imagined that less than ten years later they would be shooing away a king, a crown prince, and millionaires galore who begged for a ride in their sky vehicle; that the King of Spain would be arguing why he should be a passenger when the Queen was not looking; that the Crown Prince of Germany would be pleading for a short trip which you and I now ob- tain for three to five dollars. “LOW did the Wrights—uneducated : —dare to attempt what they did?” I have heard dozens of people ask that. question. Here were two modest bicycle: mechanics, without funds and with very. little schooling, essaying to compete with” trained and learned men of science in the’ development of an epochal invention: While the Wrights were just beginning_ their study of flight as the merest novices, _ it seemed that men like Clement Ader if France, Sir Hiram Maxim in England,” Octave Chanute and Professor S. P. Lang: | ley in America, were past masters in the” study of aviation. They had built gliders,” written learned books, made model glid- ers fly, and some of them were at work on” ponderous power machines. They had prestige, money, and apparent science. Maxim was the famous inventor of the* Maxim gun. Chanute was a leading en-~ gineer. Langley was secretary of the” Smithsonian Institution, a Government museum and scientific laboratory. , Anal yet the unschooled bicycle men of Dayton, outdistancing all learned rivals in the world, succeeded in their quest, for th ment abroa

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- fac. 1phs,

pebruary, 1929 POPULAR SCIENCE MONTHLY

reated the first airplane

< which are directly derived, Fe . basic difference or wither all the mighty fleets that roam the sky today. How did they ever manage to an answer, let us go back a few years, to their boyhood and youth in the simple little homestead on Hawthorn Street in Dayton, and see how the brothers qualified themselves to sueceed where men of far greater technical learning and resources failed. HE Wright family was set- tled in Dayton permanently in 1884. Nightly after supper the two boys, Wilbur and Or- yille, toiled at the dining room table with the tools of wood carving and engraving. They turned out some useless things but advanced in the knowledge

of tools. The younger brother surpassed in his deftness with chisel and graver. Wilbur’s ability showed in a substantial chair which he built for his ail- ing mother. This boyish indoor amuse- ment was, in effect, part of a course in draftsmanship and woodworking that became a _ prime advantage in the future creation of gliders and then a power flyer. Thus the boys learned to draw plans to scale—whether a wing, motor, or propeller—and how to execute them in detail. There was more wood than metal in the first air craft, and it was well they early learned the differ- ence between ash and oak, pine and maple. This was a profitable home schooling that the Langleys and Maxims missed. A home workshop does not make everybody a great inventor, yet it develops and edges wits. m E Wrights are their own mechanics and won't let anybody do anything for them,”” was the amazed critical com- ment in later years amid their triumphs abroad. It was partly the reason, too, The former Crown Prince of Germany pleading with Crville for a ride in the air. years before, as Wilbur read books on flight to his sick brother, their wildest fancies did not picture themselves as being sought after and hon- ored by princes and presidents.

A few for their epochal achievement. Wilbur took a year’s course in the Dayton high school in 1884-5 to supple- ment his previous schooling. Science, mathematics, and history were the sub- jects he studied. His academic record seems barren, but his athletic activity led to an accident without which the world would have had no airplane today. A fellow player, in a game of shinny on the ice, accidentally struck Wilbur on the mouth with his stick, knocking out all his front upper teeth. It was a cruel injury. A surgeon bandaged the gory face. “Tl walk home,” we can hear the brave lad mumble. “Scare mother ’f I didn’t.” He had his way and walked. How could this boyish misfortune pro-

The Wrights practiced team- work even in bicycle races, ~~ Orville by a push.

King Alfonso of Spain, left, shown arguing with Wilbur why he should be given a ride in the Wright plane when the Queen was not looking. thowed him how the machine worked, but turned him down on flying. vr Wilbur Wilbur starting ~ 43 mote a world discovery? Among the ef- fects of the injury were heart and stomach trouble. There was a long period of deli- cate health, if not semi-invalidism. The effect in poor health kept Wilbur at home for years. He did not travel or marry, like his elder brothers. HE age difference between himself and Orville was equalized, making possible their collaboration in inventive feats, which they continued to a trium- phant end. Orville was fourteen and in the eighth grade of public school when he formed a partnership with another boy in the print- ing business. The partner was Ed Sines, a crony from early childhood. The print shop, in the Sines kitchen, was equipped with a toy press, a hellbox of junk type, a few wood engravings made by Orville, and some of Mrs. Sines’ embroidery stamps, all very useful in printing and decorating a catalogue. For the Wrights, printing became a needed enlargement of mechan- ical talent on the road to the flying machine. It also developed into a practical source of bread - and - butter. Father - Wright cheered the struggling partners with a donation of twenty-five pounds of second- hand brevier type at the same time he prompted Wilbur and Lorin to trade their jointly owned rowboat, which Wilbur had built, for a real press to be presented to Orville. This press was 3 by -5 inches, self-inking, famed as the ‘‘Model.”” When the partners added to this outfit some job type, they were soon emboldened to launch a school paper, styled the Midget. At sixteen, Orville decided to build a printing press. He took sticks from the family woodpile and shaped them on the turning-lathe that had been earlier con- jured from a similar stack of kitchen stove fuel. A junk shop supplied a metal roller which only needed a gravel filling for weight and plugging of the ends with wooden disks. After inking a form of type on its flat bed, a sheet of paper was set in place and subjected to the pressure of the gravel-loaded roller. It worked. But Wilbur cast his eye on the outfit and saw how it could be bettered. E CAN imagine the youthful Wilbur saying: “This press is all right, Orv, but it would save work if you didn’t have to run up and down with that big roller. Look. I'll fix a lever to shoot the roller back and forth. Then you just stand and move the lever with one hand.” The elder also helped on a tym- panum device, and the pair coaxed some speed out of the woodpile press with Orv at the lever and Wilbur ) inking and feeding. Later they de- vised and built an ingenious mech- anism that folded printed papers as they came from the press. All this was typical of the collabora- tion between the brothers. The younger, full of eager visions, began projects which

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POPULAR SCIENCE MONTHLY At sixteen, Orville built a printing press out of sticks from the family woodpile. were scrutinized and improved bytheelder. Thus, if we should tag the essential parts of the airplane with the initials of the joint creators, indicating priority of concept and improvement, the results would be: Wing warp or flap for sidewise balance, O, W; vertical rudder for sidewise bal- ance, O, W; horizontal rudder for fore- and-aft balance, W; wing curve, O, W; propeller curve, simultaneously W and O. , AS boys, the Wrights were able to build a rather intricate machine out of nothing, we can understand how in raanhood they assembled hack saw blades and other junk in a bicycle shop to create the world’s pioneer device for the correct measurement of air pressure that was a prerequisite to the solution of the flight problem. When the brothers resolved in the late winter of 1888 to publish a weekly news- paper, they wanted a sizable printing press. I imagine Mrs. Wright looked with dismay on the family woodpile, for the weather was cold. But the press was needed. It was the most ambitious of the inventors’ efforts up to this time. A secondhand tombstone served as a flat bed for the press. There was a massive roller and an amplitude of wheels, pinions, pul- leys, gears, and levers. “Every part of this press ran at full speed,” a member of the family told me. “It was the liveliest thing you ever saw. The racket it made was terrible.” The West Side News, printed on the new press, made its bow to the public in March, with Wilbur as editor and Orville filling the position of business manager. The boys’ mother died on July fourth, 1889. She left her sons a rich legacy—skill of hand and eye of her craftsman parent, original minds, the example of her own ability to create, and her sympathetic en- couragement of their childish and boyish play-steps toward the making of dreams come true. If that mother could have seen in a magic crystal of the future her sons standing in the White House, receiving gold medals at the hands of President Taft—Wilbur and Orville striding down a field with the King of Italy be- tween them—Wilbur aflight with his sister Katharine in The Wright brothers’ bicycle shop on Third Street, Dayton—a “‘kindergarten’”’ where they acquired craftsmanship to build the airplane. the presence of His Bri- tannic Majesty Edward VIL — Orville smiled upon by an emperor and cheered by 200,000 massed spectators of whom many sought to touch the hem of his garment — would she have shook her head or with a startled gasp, weeping, have be- lieved? There is no limit to the hopeful imagination of a mother! She would have believed. And taken more joy in their useful service to the world than in the pomp and glory which attended their success. With the eldest son married and the next permanently away, the home was reduced to three children and a father often absent on church trips. Fifteen- year-old Katharine tried to be a “‘ittle mother” to Wilbur, who was twenty-two, and Orville, who was eighteen. The trio became inseparable through the years, unbroken save by the intervention of death. No one else was as close to the inventors as this sister, their beloved “Sterchens,” who was their comrade and perfect confidante. F THE muse of history raised a polite eyebrow because Wilbur did not gradu- ate from high school, let her now lift the other eyebrow! Orville did not graduate when he left Dayton high school in 1889. Thus neither of the brothers even finished preparatory schooling. - The Wrights never went to college. The West Side News was turned into a daily in the spring of 1890 under the name of The Item. A funny column styled After success had come—the inventors’ father (center), with Orville at his right and Katharine, seated with friends on the lawn of their new home at Dayton. John R, McMahon, the author, can be seen beside Orville. 2048 THOITIW ZITIYIIGD Left: Orville as he appeared in 1896, at the time when the brothers began studying flight, **Predictions by the Weather Prophet”’ was in. cluded among the tasks of Editor Wilbur. Orville’s job was to make big mer. chants sign on the dotted line. The Item luckily died in three months and the relieved owners turned to job printing. In the output of Wright & Wright, Job Printers, were pamphlets up to 100 pages, minutes of the United Brethren Church, and a journal for col- ored people. The latter was edited by Paul Lawrence Dunbar, a young negm who had been Orville’s classmate in high school. UNBAR was given to original poems which he recited in the print shop. One day he scribbled on the wall an effort that is doubtless omitted from the col- lection which brought fame to the Afro- American poet. But it has an interesting touch of appreciation, if not prophecy: Orville Wright is out of sight In the printing business. No other mind is half so bright As his’n is. The Wrights were as pleased with Dun- bar’s later success with his Pegasus of poetry as he was over their feat witha mechanical steed of the air. The brothers were strong in loyalty to early and old friends. The job printers branched out in 1892 with the addition of a bicycle repair shop to their line. No doubt they were lured into this by the idea of playing with a new machine, the ball bear- ing “safety” with compressed air within rubber tires. “Wright Cycle Co.” was the legend put above the modest shop on Third Street. That sign remained blandly un- changed through the years, long after the proprietors advanced their activities from the creation of ground to aerial vehicles. It is in- teresting to consider that the bicycle trade was a kinder- garten to many who later found fame and fortune in automobiles and aircraft. For the Wrights it was a real stepping stone toward the (Continued on page 152) Sicily, Etna. volcan Vulcan Fro mount maine there | lava S strean side, its in ahead Toniat it had

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1 Dun- sus of with a others id old 1 1892 r shop lured vith a bear- ressed ires. is the odest That r un- years, ities ‘ound is in- t the nder- later le in . For the February ’ 1929 Tides Make the Earth Boil Over By EDWIN W. TEALE ECENTLY the world read that thousands of refugees, carrying pitiful bundles of salvaged goods, were clogging the roads of eastern Sicily, fleeing from an eruption of Mt. Fina. For five years this 10,758-foot yoleano, fringed with villages and vine- yards at its base, had been quiet. Then Vulean’s forge flared anew. From an opening in the side of the mountain—which, strangely enough, re- mained covered with snow at its top!— there crept a devastating dragon of fiery lava sixty feet high. Dividing into three streams, it advanced down the mountain- side, devouring trees and buildings in its incandescent flood, and pushed ahead for fifteen miles toward the Ionian Sea. When, after twelve days, it had run its course, a town and two villages had disappeared, 7,000 people were homeless, and 10,000 fertile acres had turned to ridges of stone. Etna had again proved its right to the crimson dot that marks it on the map! If you look over a detailed map of the world you will find three or four hundred of these red dots, each marking a volcano of comparatively recent ac- tivity. Not all active volcanos erupt, as did Mt. Etna, like a boiled- over pot. Many explode, shoot- ing dust and ashes miles into the air. The nonexplosive char- acter of Etna is ascribed by voleanologists to the fact that its lava is a relatively thin liquid which allows steam and gas bubbles to escape readily. In explosive vol- canos, the lava is thick. It holds back steam and gas stub- bornly, causing im- mense pressure be- neath, and eventu- POPULAR SCIENCE MONTHLY Left: Mt. Etna’s latest eruption. Be- low: Refugees flee- ing down the side of the mountain. © S. Maehara. Courtesy Dr. T. A. Jaggar With this terrific explosion not long ago, Mt. Kilauea in Hawaii, normally tranquil, went on rampage. As vol- canos age, eruptions are less frequent and more violent. perature was 100 degrees C. lower than on the surface. One explanation is that one third of the gas from the crater is hydrogen, which burns at the surface, increasing heat. As volcanos grow old, their eruptions become less frequent and more violent. Etna is comparatively young, possibly not older than 100,000 years. The most destruc- tive of the fiery mountains are tranquil for long peri- ods. Bondaison, in Japan, was quiet for 1,000 years before its outbreak in 1888. Vesuvius, most famous volcano in the world, was described as being verdure-clad before it belched death upon Pompeii. The most ter- rible of all known volcanic disasters occurred on the Island of Martinique, in 1902, after Mount Pelee had slumbered for fifty years. A single puff of its fiery breath snuffed out 30,000 lives in the city of St. Pierre. A single human being remained alive through the disaster—a negro prisoner locked in an underground dungeon. At one time it was be- lieved that all volcanic lava came from a central reservoir, formed ally a violent eruption. FEW years ago, scientists discovered the strange fact that lava is hotter at the surface of a crater than in its interior! Dr. Arthur L. Day, director of the geophysical laboratory of the Carnegie Institution, Washing- ton, D.C., descended to the very floor of the fire pit of Kilauea, in Hawaii, wearing a gas mask as protection against the poisonous fumes. With flames shooting all by the molten heart of our globe. Now, however, the earth’s inte- rior is believed to be more rigid than strongest steel. Instead of being of deep-seated origin, volcanos are now thought of as a ‘‘skin disease” of the earth. Lava is believed to originate at moder- ate depths, which Charles F. Talman, of the U. S. Weather Bureau, says probably never ex- ceeds half a dozen miles. Some volcanologists hold that lava is carried by rootlike channels run- ning around the earth; others about him, and the heat charring the soles of his heavy shoes, he took measurements which re- vealed that twenty feet below the surface of the lava the tem- A seething caldron of molten lava. This spectacular night photo- graph shows a vent in Kilauea after a violent explosion. The interior is white hot and hung with glowing stalactites. Scien- tists, braving death to measure heat in Kilauea’s fire pit, have found the lava hotter at the surface than in crater’s interior. that small individual pockets or reservoirs of molten rock are formed beneath each crater. (Continued on page 151)

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POPULAR SCIENCE MONTHLY February, 194 — Bomb “Warship” on the Desert California National Guardsmen painting the outline of the U.S. S. California on the glaring white sand of the Mohave Desert, as a target for air bombers. TH whining steel propellers, five California National Guard air- planes recently wheeled into position over the shimmering Mohave Desert and released a series of high-explosive bombs in a new type of practice maneuver. On the bed of a dry lake below, the exact outline of the U. S. S. California, painted to scale, had been shaped by guardsmen, using black crude oil for paint, and brooms for brushes. Even the turrets and big guns of the naval giant stood out, exactly reproduced in size by the black oil upon the white, alkali-covered desert floor. Toward this strange battleship of sand the speedy war planes discharged their bombs—thirty-two in all. As each struck, Life-Size Dreadnaught, it detonated with a roar, raising a huge cloud of smoke and dust. Three of these death-dealing bombs struck at almost the same time, all landing within the lines marking the deck of the dreadnaught. Painted on Sand, Blown to Bits by Shower of Missiles from the Air in Amazing War Game Attaching bombs to releas- ing mechanism under lower wings of the bombing plane. a mee When the flock of war birds headed back for the home field, the outline of the ship had been blown to pieces and its position was marked by a series of holes torn by the exploding bombs. Do You Want to Get Into Aviation ? Do you want to know the real facts about learning to fly? How to get started? How to figure the cost? How to choose a school? How to find an opening after you have your pilot’s license? A Series of Articles Will Tell You How The most complete series upon the subject ever puolished. Authoritative. Helpful. Thrilling. Useful hints that will aid you in getting started. Facts you will want to know from first-hand information. Advice that comes to you from the experiences of famous flying men. The series will Begin Next Month Watch for it. It will aid you in learning to fly. It will help you in finding a place in aviation. Don’t miss the first installment in the March POPULAR SCIENCE MONTHLY—Order Your Copy Now! od

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—a = 2d back he ship osition orn by February: 1929 Prof. Harry Steenbock, of the University of Wisconsin, who dis- covered that food bathed in sun- light will aid in preventing disease, and presented mankind with amazing new health cereals. ITHIN the last few weeks a new breakfast food has ap- peared on the shelves of grocery stores throughout the country. During its making, it has been bathed in artificial sunshine from high-powered electric lamps. It is the first of new “irradiated” health foods that you may soon expect to see upon your grocer’s shelves. And it is the first result of a sensational process that might have been worth a million dollars or more to a University of Wis- consin professor, had he not preferred to give it away. ‘When Prof. Harry Steenbock, the originator of the process, made his astounding discovery that sunlight- wt i. POPULAR SCIENCE MONTHLY bathed food will prevent rickets, dread bone disease, and will probably help to check tuberculosis and anemia, he feared that his knowledge might fall into the hands of unscrupulous profiteers. So he snapped off the powerful sunlight lamps in his laboratory, put back in their cages the white rats that had led him to the epoch-making find, and applied for a patent. When he obtained it, he pre- sented the food-making process, patents and all, to the University of Wisconsin. In a Chicago hospital, crippled children suffering from bone tuberculosis are treated with artificial sunlight from ultra-violet lamps. Here one of the small patients is having his sun bath. 47 ou Can Eat Now Y Sunshine! Here Is the Story of a Man Who Gave Away His $1,000,000 Dis- covery to Make Folks Healthy—How the Sun Is Being Put to Work By FRANK PARKER STOCKBRIDGE By eating “sunburned”’ food, everyone, by proxy at least, can now bask in the sun’s rays that our distant ancestors once worshiped and that our modern physicians have found vital to health. Great manufacturers of food products heard of the discovery, came to Steen- bock, and were referred to the Univer- sity’s trustees. There they learned that they would be licensed to use the sunning process, provided they did not increase the price of their product because of it. Several important firms accepted the opportunity, one of them now paying the University $50,000 a year for its license. Now the first of the new products, an irradiated cereal, is being produced com- mercially. Others are to follow soon. OME day science will find out defi- nitely what influence the light of the sun—particularly the ultra-violet rays, which Dr. Steenbock and others produce artificially with their so called “sunlight lamps”—has upon human life, and how - and why. The Incas of Old Peru, the ancient Zoroastrians and their successors, the Parsees of today, and many other religious cults, have held that all life comes from the sun, and modern research seems to be proving that they were right. We have long used the expression “a healthy tan,” in referring to the darkening of the skin by exposure to sunlight. The knowledge that this burning of the skin is done by invisible ultra-violet rays is very recent; still newer is the discovery that these ultra-violet rays carry into the body life-giving properties to which the name of vitamins has been given; newer yet is the knowledge that unless we take these vitamins into our bodies with our food, as well as getting them into our systems through our skins, we cannot live healthily nor very long. Women are beating the male sex to it in the application of this aspect of science

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48 Making artificial suns. Here is a view in a factory where ultra-violet lamps are being raanufactured to supply sunlight treatment. to life, Dr. Ephraim R. Mulford, pres- ident of the New Jersey Medical So- ciety, told a convention of doctors the other day. Already they are healthier and longer-lived than men, more resistant to disease and more resilient under strain. Dr. Mulford attributes this to the modern fashion among women of wearing fewer and scantier clothing. They expose them- selves to the life-giving ultra-violet rays, whereas men persist in covering their bodies from neck to ankle with thick, dark clothing. The whiter and more porous the material of our cloth- ing, the more easily do the ultra-violet rays of the sun penetrate to the skin, the United States Bureau of Standards re- ports. Dyed fabrics, and even those slightly yellowed by age, shut them off almost completely. The one-piece bath- ing suit or the still scantier costume of the Oriental dancer would seem to be more in line with what Nature intended us to wear! E DIG our graves with our teeth by rejecting the vitamin-bearing foods in favor of sugar and starches, says Dr. Seale Harris, of Birmingham, Ala., in a report to the American Medical Associa- tion. Lowered resistance to infections of all kinds, in the nose and throat as well as in the stomach and intestines, results from a diet consisting mainly of white flour bread, white potatoes, white rice, lean meats, sugar-saturated coffee, sugar- laden desserts, sweetened soft drinks, and candy, says Dr. Harris, comparing the increased prevalence of abdominal disease with the increase in sugar consumption. Fifty years ago the average person ate twenty-six pounds of sugar a year; now he eats 106 pounds. Frequent colds, pneumonia, tuberculosis, appendicitis, stomach ulcers and gall-bladder disease are attributed to lack of vitamins in the diet of the average sedentary American. Catch your own food and eat it raw and ou will get all the vitamins you need. The human machine functions best when we eat only what we can capture, pluck POPULAR SCIENCE MONTHLY An expert of the U. S. Bureau of Standards tests the proper weight of cotton and rayon cloth to admit the health-giving ultra-violet rays. or dig barehanded, combining muscular effort and exposure of our bodies to the sun with a diet which is rich in vitamins because it, too, has been exposed to the sun. Since that mode of life is impractical in our industrial civilization the best practical compromise is probably to eat a much higher proportion of fats, nuts, raw fruit, and green vegetables, wear the lightest clothes we can tolerate, walk in the sunlight as much as we can, and trust to luck. HILE Prof. Steenbock was feeding cereal to white rats in his darkened mid-Western laboratory, other experi- menters here and abroad were bottling sunshine for human needs. From lab- oratories in England and Germany came the news that a substance had been dis- covered which, exposed to sunshine, or ultra-violet light, became a remedy thousands of times as potent as cod liver oil. Six ounces of it equal a ton of the fish oil, it is said. Known as ergosterol, this substance, formed from yeast and activated by sunlight, is present in small quantities in every healthy person. But let it be lacking, and a dose so small that it could hardly be measured would remedy the trouble. So powerful is this substance that an overdose of a few grains might prove deadlier than arsenic. How this magic substance was found is in itself an absorbing story, that started with efforts of scientists to make February, 1999 cod liver oil more pleasant to take. first attempts to make the oil palatabj by purifying it, destroyed its curative value. That gave the first clue; perha the beneficial ingredient was actually 4s impurity. Prof. George Barger, of the University of Edinburgh, pursued this clue and found the answer—the whole medicinal value of the oil was confined to ergosterol, which is found as an jm. purity in fats. — Dr. Adolf Windaus, a Ge. man expert of the University of Goettingen, proved that by exposing ergosterol to sunshine or to ultra-vidlet lamps he could obtain a substanee with all the curative power of cod liver oil and digestible by the most sensitive stomach. For that discovery he has 3 been awarded the Nobel Prize in chemistry for 1928, a cash award of more than $40,000. In other words, cod . liver oil owes its benef. cent effect wholly to an impurity—which, in turn, owes its power to sunlight that filters through thé water to the swimming fish. When sunlight hits ergosterol, it turns it into “vitamin D”—one of those mysterious, nec- essary components of foods which scientists now believe owe their health-giving potency to the fact that they absorb and retain sunshine. Vi- tamin D, which is the rickets-preventing vita- min, is manufactured in the human body by an interesting proc- ess which scientists are just now begin- ning to understand. Ergosterol, already contained in the body, finds its way to the surface of the skin, where it is bathed in sunlight. Then it is reabsorbed with its health-giving vitamins. It is because it aids in this process that cautious bath- ing in the artificial sunshine of suitable electric lamps is now recommended. by medical men, who also believe that people whose bodily “sun-bottling” ap- paratus is defective can make up the deficiency in an indirect way by eating food that has been treated with sunshine. O DEMONSTRATE that sun baths can be taken in food, Professor Steen- bock raised two broods of white rats. One brood he deprived of a part of their normal diet, and they developed the bone disease of rickets. The other brood he sun-bathed daily in the artificial light of mercury lamps. At length he killed the rats of the second brood and fed an extract of their livers to the undernour- ished ones. The ricket-afflicted rats be came healthy again. Thus he proved that treatment with ultra-violet rays could be given indirectly, in food. Next he exposed quantities of flour and farina, rolled oats and other cereals, to the powerful rays of mercury lamps and fed them to ricket-afflicted rats. These rats, too, recovered. Then Professor Steenbock announced his discovery of how to put healthful sun- (Continued on page 158) 7?’ >» —————e rr |

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Ary, 1929 ke. The alatable Curative Perhaps ually an > Of the ued this © whole fined to an im. » a Ger. TSity of *Xposing "a-Vidlet ibstance od liver ensitive he has e Nobel try for vard of 00. ds, cod benefi- olly to rich, in wer to filters r to the it hits Irns it ”—one US, nee- nts of ientists > their ency to absorb ne. Vi- is the . vita- ctured 3 proc- begin- ready vay to bathed d with ecause } bath- litable ed. by that a ap- p the eating shine. pebruary, 1929 A new engineering wonder— ~ the tiny ‘“‘sleeping car’’ hotel, perched like a bird house on the pinnacle of Jugspitze. Sky Railway Runs to Strange Hotel combined recently in a single enter- prise that may be numbered among the wonders of the world. One is the fa- mous hanging-car aerial cableway that climbs to the top of Germany’s highest mountain peak, the Zugspitze, more than two miles above sea level. The other is the construction of the world’s loftiest all-year hotel, perched on a sharp crag that forms the very pinnacle of the moun- [= great engineering feats were tain. The second was made possible by the first. The hotel, a Lilliputian hostelry smaller than a regulation-sized sleeping car, prob- ably involved more problems of construc- tion than the largest hotel ever built. It was designed like a sleeping car, not to be fantastic, but because of the meager space available, and also because of the difficult POPULAR SCIENCE MONTHLY 49 Going up! This little car, hanging on an aerial cableway nearly two miles long, carries guests to the hotel. A thrilling ride if you don’t get dizzy. At right is the hanging car, with load of passengers, near the mountain top. The tiny “sleeping car” took six months in building. The first task was to break up 2,500 cubic yards of rock to make a suitable foothold for the hotel. Wood construction was used because of the drastic change in tem- perature, which caused enormous expansion and shrinkage of ma- terial, and because ee- ment froze before it could be used. Almost like the sheer wall of a sky- scraper is the rugged mountain-side. and dangerous task of lifting materials to its lofty perch. A landing place near the sum- mit, used by the hanging-car cableway, gave rise to the auda- cious idea of providing a mod- ern-equipped mountain-top ho- tel. The cableway, first of its kind, extends from a station in Standing on the balcony, high above the clouds, visitors at the tiny mountain-top hotel are thrilled by the mar- velous bird's-eye view of mountain tops and valleys below. Austria, 2,800 feet above sea level, up 11,000 feet to the mountain’s summit. Storms, snow, and ice greatly hampered the work. The peak was swept by a seventy-mile gale and in winter the thermometer dropped to zero and below. The crews of eighty men had to be changed from week to week, so gruelling was the task. Three men were lost; one fell into a chasm and two were caught in snow slides. All building materials, machinery for an electric power plant, furnishings, heavy porcelain plumbing and pipes, furniture and equipment for a restaurant capable of serving 250 hungry guests at a single meal, pumps for a reservoir, a large steam heating plant, food and fuel for the workmen, and finally the workmen them- selves, had to be hauled up the rugged mountain sides or carried in the tiny cable cars that hold only twelve people and take twenty minutes for each trip! There are berths for seventy-three in the “‘sleeping car.” First-class bedrooms are “outside,” with windows looking upon the magnificent view below. The total cost of the Zugspitze cable- way and the hotel was about $1,000,000.

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er en a en Ticats allem Along the oe VERY shade and tint can be re- duced to a numerical formula, expressed in figures, by means of { a device known as the recording spectrophotometer, recently in- vented by Professor Arthur C. Hardy, of the Massachusetts Institute of Technol- ogy. The apparatus automatically an- alyzes the light rays reflected from any object of any color and records in ink, on a chart, the precise proportion of each of the primary colors, red, yellow and blue, which combine to make the shade under observation. The chart reading is easily reduced to figures, so that it is possible to describe any color or tint in numerals which will enable anyone having access to one of Professor Hardy’s instruments to match it perfectly without a sample. The practical uses of this device are innumerable. A fashion expert visiting Paris for an American dress manufactur- er, for example, can cable the mathe- matical formula of the newest fashionable shades so that they can be reproduced precisely without delay. To the man whose wife asks him to go to the store and match a piece of silk or a pair of stockings it should prove an inestimable boon. No longer will he have to try to discover what the shopkeeper means by such vague terms as “ecru,” “mauve,” “elephants breath” or “moonlight,” actual names given to colors! Farms in the Sahara? ECLAMATION of the Sahara Des- ert, long discussed, is now receiving attention as a serious project by the French government. Dwight Braman, of Boston, Mass., an irrigation engineer, has worked out the plan for letting in the Mediterranean through canals and dam- POPULAR SCIENCE MONTHLY Necklace 35,000 Years Old Henry Field, Assistant Curator of Physical Anthropology, Field Museum, Chicago, is seen here examining a necklace believed to be 35,000 years old, found in a cave in south- western France. It contains 250 beads carved, it is thought, from the tusks of mammoths, pared from the intestinal membrane of the ox, and derives its name from its use in the final process of manufacturing gold leaf. Sheets of gold are reduced by pre- vious beating to such thinness that 950 of them, piled alternately with squares of the skin, measure only three quarters of an inch in thickness. This pile, or “mold,” is then beaten for four hours with a seven- pound hammer until each sheet of gold leaf is only 1/150,000 of an inch thick. February, 1929 Road of Progress The thinness, toughness, and imper. viousness of the goldbeaters’ skin hag made it heretofore the only substance light and tight enough for airship gas cells. Each skin measures five inches square, and it took 500,000 of them to make the gas cells for the dirigible Ig Angeles. Commenting on that fact, an Irish newspaper recently gravely informed its readers that the little animal known ag the goldbeater, a native of North Amer. ica, which derives its name from its habit of beating or stamping upon the ground in the vicinity of the gold mines of the Far West, was in danger of extinction, so many were being killed for their skins to make airships! Will the Ocean Overflow ? O MOST of-us Commander Byrd’s expedition to the Antarctic savors more of adventure than of science; but if his researches on the south polar ice cap answer but one question they may prove of the greatest value to the world. That question is: Is the Antarctic ice cap melting? If it is, then the seacoast cities of the world might better begin now to move inland, to high ground, for the complete melting of the Antarctic ice would re- lease enough water, now stored as ice, to raise the level of the whole ocean by fifty feet, according to Sir Edgeworth David, of Sydney, Australia, a distinguished explorer and geologist. There seems to be ground for belief that the tradition of a world-wide flood, persistent among all ancient peoples, may have originated in the rise of the oceans when the Arctic ice cap melted at the end of the last Ice Age, approximately twenty thousand years ago. ming the rivers which flow down from the Atlas Moun- [ tains. This would create a great inland sea covering 30,000 square miles. The mois- ture from evaporation would change the climate for hun- dreds of miles in all directions, possibly affecting that of south- ern Europe as well. The soil is rich and, with water available, would be highly productive. This project, if carried out, might change the whole course of international trade and put North Africa back on the map as a center of civilization. New Material for Airship Bags HE U.S. Bureau of Stand- ards announces that its technicians have developed a substitute for goldbeaters’ skin for use in the manufac- ture of the gas cells which, in- flated with hydrogen or he- lium, lift an airship. Goldbeaters’ skin is an ex- pensive product. It is pre- New Machine to Fight Cancer The newest aid in the study and treatment of cancer is this electrical machine, perfected by Charles Weyl, of the University of Pennsylvania. It measures the acid-alka- line balance of the blood in terms of voltage. Detects Artificial Pearls By photographing the heart of a pearl, the instrument at the right, invented by M. Reisler, whether it is genuine. A small camera is focused on the gem through a powerful lens. a French chemist, determines New Cancer Hope ANCER is a disease for which no definite cure has been found ex- cept the use of the knife in its early stages. One woman in eight and one man in fourteen dies of cancer. It occurs most frequently in people whose blood is alkaline. Dr. Charles Mayo, famous surgeon of Rochester, th Min’ canc are sciel crim steat sult deve Uni chin

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Ty, 1929 38 mper. stance P gas ncheg m to € Log Trish od its mn ag \mer- habit ound f the M, 80 ns to »? yrd’s LVors ut if cap rove end February, 1929 .POPULAR SCIENCE MONTHLY 51 Brief Bits of Fact and Interesting Comment from the Month’s Records of Discovery and Invention Minn., recently told the American Public Health Association that the tendency to cancer is hereditary. Cuban authorities are considering a proposal to permit scientists to experiment on condemned criminals with cancer inoculations, in- stead of putting them to death. A treatment, less repugnant, may re- sult from the use of a machine recently developed by Dr. Charles Weyl, of the University of Pennsylvania. This ma- chine diagnoses the disease and directs its treatment by measuring the relative amounts of alkali and acid in the blood. An Artificial Heart! IFE remains one of the unexplained phenomena of the universe. It seems improbable that scientists ever will be able to produce life from nonliving ma- terials, but through an amazing series of laboratory experiments many things about life and death are being learned. Recently the Moscow Scientific Insti- tute reported that the head of a dog had been kept alive for three hours after it had been severed from the body. And in a glass jar at the Rockefeller Institute of Medical Research in New York there is part of a chicken’s heart which the fa- mous Dr. Alexis Carrel has kept alive for nearly twenty years. The Moscow experiment, conducted by §. J. Brukjanenko and Dr. S. I. Chech, after the animal had been placed under an anesthetic, was accomplished by means of an artificial heart made of steel and rubber which pumped blood to the dog’s head. The experimenters declared that the detached head swallowed food, al- though there was no stomach for it to go into, snarled and bared its teeth, and responded to the slightest touch. Tests made with quinine and cheese indicated that it was capable of tasting. In a similar experiment in Russia, a monkey which apparently had been dead for hours was resuscitated by the injec- tion of its own blood, and at last report was alive and normal. Just what the future may bring from these experiments The Tropics in a Box Above is the world’s strangest tropical cotton plantation—a glass box only a yard square, where plants grow under blazing electric “sunlight”? turned on and off by clockwork. It is used in the Rothampsted Agricultural Experiment Station, England, to study a disease of African cot- ton fields. Left: Examining soil it is impossible to tell, but from such research physicians learned how to re- suscitate patients, after the heart had stopped, by the injection of adrenalin. No Fire in Redheads ? SCIENTIFIC pronouncement which may start lively arguments comes from a report of the British Social Hy- giene Council. This indicates a belief that redheads, instead of being natural fighters and fiery adventurers, are really victims of an in- born inferiority complex. It is an inter- esting theory, if difficult of proof. It has for its foundation, of course, the idea that redheads as children are so Studies Thunderbolts from Glass Cage Unscathed amid crashing artificial lightning bolts in the new high-voltage laboratory of Stanford University,.California, is an insulated glass cage. Here Dr. Harris J. Ryan, head of the electrical engineering department, sits in safety while he studies the effects of voltages many times higher than those of commercial transmission. At the right Doctor Harris is seen at the switchboard that controls the powerful current. bacteria employed by planters to increase their crop yield. teased that they are forced into being vigorously on the offensive-defensive, until it becomes a habit. Schoolroom jests often have a lasting effect on the lives of people. It is related of Napoleon that he first determined to be a soldier when a schoolmate twitted him about his small stature, saying that there wasn’t enough of him to make a soldier. Every Man His Own Still ATURE has slight regard for the Eighteenth Amendment, but sees to it that every human being has his or her regular daily supply of alcohol. Three thousandths of one percent of the total weight of the normal human body con- sists of alcohol, says the Journal of the American Medical Association. Each one of us is constantly manufacturing alcohol from the sugars, starches, and yeasts we eat as food, but it would take more than a hundred times as much as we can get in this way to produce intoxi- cation. To discover what goes on in the chemical laboratory of the human body is a quest upon which scientists are working more than on any other single problem. The mechanics of the body, considered as a machine, have long been well understood; its chemistry still holds fascin- ating mysteries. It may take a long time to uncover all of them, but we ‘have plenty of time ahead of us. A billion years, at least, is the latest estimate of the future duration of the earth, according to Prof. R. A. Millikan, of the California (Continued on page 150)

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52 EAR Peekskill, N. Y., the old Mohegan granite quarry, un- worked for years, has been re- opened to supply stone for the building of the great Cathedral of St. John the Di- vine, on Morningside Heights, New York City. Amid the skyscrapers of the me- tropolis, the cathedral will be unique in that it will contain no steel or wood. It is being constructed entirely of stone, to last for centuries. The granite extracted from the quarry is of a light brown color and is reputed to hold its color in spite of weathering and the onslaughts of time. ‘The huge masses of rock are blasted out Dr. E. W. Brandes, sugar plant specialist of the De- partment of Agriculture,with one of the new varieties. Cathedral POPULAR SCIENCE MONTHLY February, 199 Blasted from Cliffs Turning the rocks into a mighty edifice of lasting beauty. Right: A great block of granite blasted from the quar- ry. Left: Stone cutters fash- ioning a desiga above one of the cathedral A huge granite slab being cut by giant car- borundum wheel, cooled by a stream of water. in solid chunks, cut in pieces, and finally fitted into place at the cathedral. The cutting is done by a carborundum disk, spinning at high speed and pressed down into the hard stone by a weight above. NE of these days you may be sweetening your cereal, or your coffee, with an entirely new brand of sugar—scouted for by airplane, found by a searching party crashing through the brush of New Guinea wilds, and brought back to this country with 166 other varieties by Dr. E. W. Brandes, sugar plant specialist of the U. S. Department of Agriculture. Cuttings of the new sugar plants, with which Dr. Brandes has just re- turned from an eight-months’ ex- pedition to this tropical Pacific island north of Australia, have been planted in the Government agricul- tural station at Rosslyn, Va. At the end of a year new cuttings from these plants will be taken to the cane fields of the Southern States to see if one of the many varieties will prove resistant to the curious mosaic disease that menaces native crops. During the operation water is poured over the disk and stone to keep them cool, as illustrated at the left. When the slabs have been cut to the desired shapes, they are transported by motor truck to the site of construction. Each piece is marked carefully to in- dicate the exact position it will occupy in the building. All that is necessary is for the workmen to fit the pieces together and cement them in place. The granite edifice, which is expected to last at least twenty centuries after it is completed, will be the third largest cathe- dral in the world. St. Peter’s at Rome and the cathedral of Seville, Spain, will be the only ones surpassing it in size. It is estimated that at least ten years will elapse before the structure is completed. Airplane Explorers Find a New Sugar It will be several years, Dr. Brandes says, before it will be known whether any one of his new varieties is disease-proof, but there is good reason to believe that some one of them, or some hybrid pro- duced from it, may revolutionize the sugar industry. One of the varieties that Dr. Brandes found grew to a height of thirty feet. It is not rich in sugar but might prove useful for grafting purposes. The expedition was the first ever to prospect for new plant life by airplane. In all, Dr. Brandes and his party traveled 10,000 miles by plane, 700 miles by canoe, and 400 on foot. Many of the places he explored had never before been visited by white men. They are dense tropical jun- gles, and are inhabited only by a few wandering tribes of natives. New Guinea is believed to be the an- cestral home of all sugar plants, which © have spread to other regions of the world by transplanting.

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ary, 1929 iter is stone trated -n cut 'Y are ck to Each to in- t will 1 that kmen - and ected r it is athe- Rome , will It : will eted. ndes any roof, that the ndes sef ul r to ane, eled noe, s he 1 by jun- few an- Lich | orld February, 1929 POPULAR SCIENCE MONTHLY One of the latest seaplanes, the powerful “Corsair,’’ designed for use with U. S. battleships, is being hoisted aboard. Vought New Marvels of Plane Design Astonishing Secrets of Engineering Behind the Latest Triumphs of Speed, Power, and Reliability in Aircraft HE other day a Curtiss Army plane, equipped with a Wright Whirlwind motor, sped over Langley Field, Va., at 137 miles anhour. That was a pretty good clip for this type of machine, though not unusual. The unusual part of it was that the tachometer on the pilot’s dashboard showed the propeller turning over at the rate of only 1,900 revolutions a minute. To an Army pilot, that is almost miraculous, because at this pro- peller speed the best such a plane ordinarily will do is 118 miles an hour. Where did the extra speed come from? Over the nose of the machine, hiding most of the engine, was mounted @ curious cowling that re- sembled a bottom-up bowl with the base knocked out. The hole allowed the pro- peller shaft to poke through. Known as a “Venturi cowl- ing,” this device, just de- veloped by the National Advisory Committee for Aeronautics, slashes the nor- mal drag on a plane of the air whistling past an air- cooled engine. By making the air stream pass in a smooth stream around the fuselage, it adds more than By ROBERT T. POUND plane took the air with a cargo weighing more than two and a half times as much as the plane itself! It was the greatest load ever carried by a heavier-than-air machine. In this absorbing article, inside facts and secrets of engineering that have made possi- ble the marvelous speed, strength, and light- ness of modern flying machines are revealed by a veteran Army airman. [: CALIFORNIA, recently, a 2,000-pound — How new plane models are tested. Recording instruments give experts in New York University aeronautical laboratory results of wind tunnel test. thirty percent to the effective horsepower of an air-cooled plane in flight. Military experts hail the in- vention as the most valuable single contribution to airplane efficiency since the war. It is an example of efforts to improve the whole design of airplanes—efforts beset with difficulties of which the average man never dreams. Imagine designing an ‘airplane light enough to carry a heavy ‘pay load” in addition to its own weight—strong enough for safety —frail enough for a featherweight motor to drag through the air— and well-shaped enough to offer the least possible resistance to forward motion. Add to that, too, the fact that it must be easy to control and econom- ical to run. The wonder is not that we fly across oceans, but that we can fly at all. Strength and lightness— the two are inseparably bound together, as every airplane maker knows. It’s easy, forin- stance, to make a wing brace that is strong. It’s easy to make one that is light. But when you try to combine the two,. what. you have. is a piano-wire brace so delicate that it must be scrapped if bent, in shipping, by so much as forty-five degrees from a

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AB tie Se eo tees POPULAR SCIENCE MONTHLY — a — An example of the diver- sity of modern airplane construction. Here are some typical wing shapes of the 1929 airplanes. Curtiss AT-5 Army plane fitted with new Ven- : dé turi cowling which, by reducing wind resistance, increases plane’s speed nineteen miles an hour straight line. Otherwise a pilot, some bumpy day in the air, is likely to be in for a rough time. Every hundred pounds of added weight, in a plane, means three more horsepower to pull it. It has taken years to bring commercial planes to the point where ie Wat they can carry one pound of pay load— that. is, lifting power besides the weight “7, a am of pilot, oil, and fuel—for every three of ee total weight. That pay load means dol- lars and cents to the commercial flyer. And the fact that even now two pounds ride deadhead for every pound that is carried explains in a nutshell the high cost of commercial flying. 4: tarda Why planes use gasoline power plants. The best gasoline motors (left) weigh only a pound and a half to the horse- rubber shock absorbers to power; steam turbines (center) six to eight pounds; elec- replace broken ones on trically-driven motors (right) seven and a half pounds. machines used to train ca- Only within the last year or two have ing instruments explained. it. A new instruments been designed in making the weight-versus-strength compromise. They eliminate guesswork as to what particular parts of a plane need to be strong- est. By photographing the rise of liquids in small tubes, or the movement of beams of light from the sun or lamps on photographic paper, these instruments record pressures and strains in various parts of a plane in flight. By such measurements it was discovered not along ago that loads on a cer- tain wing part were twice what manufacturers had been allowing for. Small changes in tail struc- ture suggested hy them have improved certain planes difficult to control at critical speeds. They also cured a_ certain plane’s habit of going into a flat spin. During the war the writer won- dered why he had to wind so many February, 1929 one-ton plane, stalling six feet aboye the earth, hit the shock-absorberg with a blow of four and a half tons! After that discovery student pilots were ordered to level off a foot above ground before landing. Search continues for lighter but strong materials. Weight for weight, wood is as strong as the strongest steel. Birch is cheaper to use than metal when one wishes only a Single propeller. Lighter metals, aluminum alloys like duralumin for instance, are coming into wider use as a result of greater technical knowledge. The Ford air liners are covered with dura. lumin fourteen thousandths of ap inch thick. Many parts of an airplane could be made lighter than they are now, if the machine were to be flown only by capable men. The material, though, would snap like matchsticks under careless han- dling. And the designer, knowing that some clodhopper may clam- ber over fragile parts, adds a pound for safety and _ thereby drags more power from an already burdened engine. In ordinary en- gineering terms, a “factor of safe- ty” means that a structure is strong enough to sustain a certain number of times, say six times, its maximum load. In a plane, a fae- tor of safety of six means that it will stand six times its normal load, a very different thing. In spite of this nécessarily close mar- gin—for under certains conditions such as a steep dive a plane may practically wipe out its factor of safety—structural parts almost Scale model of world’s largest flying boat, by E. F. Burton, California aircraft designer. dets. Thepressure-detect- A striking departure from the usual airplane designs—the Fairchild amphibian monoplane, with wings that fold back when the plane is to be stored in its hangar. This was the first ship to reach the stranded Bremen at Greenly Island. Testing a forty-inch scale model of a transocean seaplane in wind tunnel, to determine air-worthiness of design. never break in flight except through stunting or careless handling. If the load can be scattered along the wings instead of all con- centrated in the body, then the structure can be made lighter. One designer moves two motors out on the wings. Ten other de- signers follow. Then another thinks of splitting the body in halves lengthwise, with a motor in front of each half. Still another ” offers a plan that calls for prac- tically no (Continued on page 134) Febru

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y, 1929 february, 1929 POPULAR SCIENCE MONTHLY 55 F o - =| When the Sky Rains Soldiers! = y lers pilots « above r but HE next war, if any, may be eight fought with parachutes! Battal- ngest ions of armed soldiers dropped Asiiaialiteliiaiaiis than from the air may play a decisive of the future, based on Single rt in tomorrow’s combats. recent inventions. | ines Several recent developments presage me we cabins | Lance this astounding innovation. From three achine mi a pa result planes speeding over Brooks Field, San ners, even airplanes The Antonio, Texas, a machine gun and its themselves, may be dura. crew of three men were dropped to earth, scat aaaan Gee of an where they set up their weapon and got py myriad eennatiaion. it into action in three minutes. Mean- could while a British invention, a detachable y are parachute-cabin for troop-carrying air- to be planes, holds promise of landing troops The a squad at a time from the air. And in » like the United States successful trials have os han: been made of parachutes designed to wing bring @ whole airplane safely to earth. lam. Over enemy lines, a fleet of transport ds a planes might fly. At a given signal, the reby bottoms would literally drop out of the eady planes and bullet-proof cabins, like great , en. packing boxes, would rain from the sky safe. to discharge load after load of infantry, eis and bring confusion in enemy ranks. tain Merely by pulling a lever, the pilot could , its launch one of the cab- fac- ins. A small pilot para- t it chute shot from the mal plane by compressed © fy uo. In air would release a Uli \ ers y nar. larger or intermediate Wy Ve ions parachute. This in turn “ e nay would exert enough r of force to drag into the ‘ost air a mammoth _para- chute that would lift i the entire cabin loose ie =] and lower it to the che earth, where shock-ab- sorbers would break its fall. Then the plane would fly back to its base for another cabin. a to n. h d l- s r " r ; Painted especially for Popuuar Scrence Monrtaty by B. G. Seielstad

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i a a ee ee MND ITE RE eh th sche My 0 56 Swimming Turtle Is ‘‘Hour Hand”’ of Novel Clock TURTLE tells you the time in a unique timepiece produced in Switz- erland. At first glance, the clock appears to be a sundial with a circular tray, filled with water, set in the face. In this tray a small imitation turtle floats, carrying a piece of steel in its beak. As the hour hand advances under the tray it attracts the turtle by means of magnets. If removed from the water and later replaced, the little turtle immediately swims across to the point on the tray directly above the hand, thus indicating the time. The eight-day-clock mechanism is wound in the usual way, and regulated after the tray and the face of the time- piece are removed. According to the importers, who re- cently brought the novel timekeeper to America, the beautiful marble base in which the clock is set makes the instru- ment suitable for display upon a pedestal or table center, serving as an ornament as well as a dependable timepiece. Floating in the tray, the little turtle moves eround the dial like the hour hand of a clock. How Much Do You Know About Astronomy ? ERE are ten questions se- lected from hundreds asked by our readers. See how many of them you can answer. Cor- rect answers are on page 166. You'll find this an entertaining way to test your knowledge in one of the most fascinating fields of science. 1. What are the stars? 2. Of what substances are the ‘sun and the stars com- ? shooting 3. How do astronomers know the distance to the moon, the sun, and the stars? 4. What is a comet? 5. Are the moon, the planets, or the stars inhabited? 6. Why does the eclipse of the sun by the moon com- pletely blot out the sun only in a narrow path? 7. What is the ring around Saturn? 8. What is beyond the stars? 9. Why can’t we see the stars in the daytime? 10. Why do stars twinkle? POPULAR SCIENCE MONTHLY Air Propeller Drives Passenger Catamaran ITH its twin hulls sinking only nine inches into the water, a unique air-driven catamaran carried . nine passengers and attained a speed of nine miles an hour with full load when put through its paces recently at Dudley, England, by its inventor, W. F. Davies. The two skull-like hulls are driven for- ward by an airplane “pusher” propeller spun at the rear of the boat by a four- cylinder, water-cooled motor. The opera- tor, steering the vessel with a wheel, sits behind the passengers in the streamlined body, near the motor. Doors, similar to those in an automobile, enable the pas- sengers to enter and leave the body of the boat easily. Strips fastened to the top of the hulls prevent accidents to passengers through slipping. Rocky Mountain Wilds Are Reserved for Science EVERAL million acres, comprising forty-two separate tracts in the Rocky Mountain Forest District, have been set ~ aside by the U. S. Department of Agricul- ture as “‘wilderness areas’’ to be used for science and recreation. Thirteen small areas in the national forests of Colorado, Wyoming, and South Dakota have been set aside for scientific observation and research, and all com- mercial and recreational activity in that territory is prohibited. A 100,000-acre wild, inaccessible area on the Washakie National Forest in Wyoming is closed to commercial use and open for recreation. The remaining twenty-eight areas, in- cluding 2,451,020 acres in Colorado, Wy- oming, South Dakota, and Minnesota, will be kept in a wild state. February, 1929 *‘Busy Bee” a Myth—He’s , Loafer, Tests Show R. LLOYD R. WATSON, of Cornel] University, a scientist who appar. ently doesn’t care what happens to oy pet illusions, has just announced the re, sults of fifteen years of research work among the bees, which showed him that these insects, accepted as symbols of jp. dustry, are really work-shirkers. The professor, who has been making bees “punch a time clock,” has diseoy. ered that, instead of toiling from mornj till night, as generally believed, they make from six to ten trips in quest of honey and loaf the remainder of the day. Mean. while, he has tried to develop a really busy breed of bees, and as a result of these experiments the number of varieties which have actually profitable character. istics has been reduced to four. Human Body’s Electricity Reported Photographed N RESEARCH work tending to show that the human nervous system is an intricate electrical network with the brain as its semiautomatic switchboard, two scientists in Munich, Germany, claim to have photographed electric current issu. ing from a man’s body. The current waves are said to have been amplified to a point at which pic. tures could be taken. The photos, it is reported, showed sparks radiating from the fingers of an outstretched hand. If the skin is dry, the experimenters declare, even the slightest motion of the fingers will produce sparks that can be “‘snapped.” The pictures further showed that the oscillations increase when the fist is closed and opened quickly. Weak Feet Walk on Air in New Arch Support % ALKING on air” is more than a figure of speech for users of a new arch support which is pumped up with a small hand pump. The air cushion, at- tached to a thin inner sole, is made of a rubber composition said to possess great strength. One of the supports is reported to have withstood a pressure equivalent to the weight of twelve heavy men. The chief advantage claimed for the invention over the ordinary metal support is increased comfort and “springiness” in walking. Inserting pneumatic arch supporter, attached to inner sole. The air cushion is pumped up.

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ary, 1929 le’s a Cornell &ppar- the re. L work 3 of in. naking discoy. orning ey and Mean. really sult of rieties racter. city ed » show 1 is an >» brain l, two 21m to t issu. - have h pie. , it is - from enters of the an be n0wed n the han 3 2 new - with n, at- 2 of a have o the chief | over eased February, 1929 s, Once Feared, Today Yield Vast Fortunes LTHOUGH a popular superstition persists to the effect that opals are harbingers ¢ f death and sorrow, Australia, the chief source of the world’s supply of these gems, derives revenue estimated at ‘tions of dollars from them. An opal valued at $5,000 was found recently near Walgett, New South Wales. Australia, too, enjoys the distinction of being the only country to produce the much-admired black opal. One specimen of this stone, weighing six and a half carats, was found in 1910 and sold for . In 1920, another specimen brought $3,000. The black opals are the product of Wallangulla Field, New South Wales. Since 1890, the total value of opals won in Australia has been estimated at $7,750,000, and this figure does not in- clude the prices realized for some very fine pieces found and sold privately. In yarious parts of New South Wales some 12,000 acres of opal-bearing country re- main unprospected. Enjoying general favor among the Greeks and Romans of antiquity, the opal fell into disrepute in the Middle Ages, when it was believed responsible for the Black Plague, of which people died by the millions. It is from that time that the superstition regarding the opal as a bringer of unhappiness dates. Queen Victoria, determined to popula- rize the gem product of her colonies, overcame much of the prejudice by pre- senting opals as wedding gifts to each of her daughters. Steam-Puffing Granddaddy of Modern Auto Found UST-COVERED and with the paint peeled from its ancient body, what is thought to be one of the earliest ances- tors of the 23,000,000 motor vehicles now in the United States was uncovered recently in an unused portion of a lab- oratory at the University of Maryland. This early “horseless carriage,”’ using steam as a source of power, is said to be the invention of the late Dr. William E. A. Aiken. Dr. Aiken was professor of chemistry at the university from 1838 to 1888. His machine—with the smokestack placed conveniently at the rear—was built long before the automobile era was ushered into America on April 19, 1892, by the success of the gasoline automobile invented and piloted by C. A. Duryea. The queer steam “ horseless carriage’’ unearthed, after nearly half a century, from a university laboratory in Maryland POPULAR SCIENCE MONTHLY Latest Ice Cream Cone Wears a Bonnet CE cream cones that wear caps, invented by C. K. Gummerson, of Pittsburgh, Pa., are said to keep the ice cream in shape from five to ten minutes longer than in ordinary cones and to protect it from dirt and street dust. The cap also may be used sepa- rately as an ice cream container. A flat baked cake wafer is supplied as a lid to protect the contents of this small ice cream “‘plate.”” The cap, which is made of the same material as the cone, can also be eaten. Life Span 100 Years by 1950? Experts Differ ENTENARIANS may be the rule instead of the exception in 1950, ac- cording to Arthur D. Rees, formerly of the University of Pennsylvania faculty, who sees no reason why a 100-year average life span should not be the usual thing. Increased knowledge of disease and dietetics will shortly extend old age far beyond the Biblical “three score and ten,”’ he believes. A life of 100 years without a day of sickness is prophesied by Dr. George Walker; of the Johns Hopkins medical faculty. Long life, he says, is not a matter of luck, but of correct eating. Less optimistic is Dr. Louis I. Dublin, statistician of the Metropoli- tan Life Insurance Co., who states that we have made little advance in lengthening life in the last eighty years. More people are living to old age, he says, but this. is be- cause we are saving more lives at younger ages, not that we have lengthened life. And Dr. Alfred E. Cohn, biologist of the Meiical Re- search Department of the Rockefeller Institute, asserts that old age is a natural proc- ess, and medicine only has made it more comfortable. a Soldering Jobs Simplified by Electric Furnace NLY eight inches long and six inches wide, a portable electric furnace has been devised for heating soldering irons for small jobs. The temperature of the heat. ing chamber is said to rise quickly to mot than 900 degrees F., but an automatic control prevents it from mounting high enough to burn the point of the soldering copper. As further protection, the tem- perature where the soldering point rests is kept lower than at the center. The furnace is designed to operate with any 110-volt electric light or power circuit and to consume current at a rate not greater than that of three 150-watt lamps. The device weighs ten pounds and is carried by means of a handle, Portable electric furnace, in foreground, heats the irons for a small soldering job on a motor. Know Your Car ARD starting is a winter motoring trouble that is avoidable. Cold weather affects the functioning of the car’s mechanism in several ways, and all of these are cumulative in causing hard starting. Much more current is con- sumed by the starter motor to start a very cold engine, due to the friction of the congealed oil. The short period of daylight causes you to use the lights more than in summer. In addi- tion, you probably do not take any long rides in cold weather. The result is that more current is drawn from the storage bat- tery than is put back by the charging generator. Consequent- ly the voltage is low and the spark correspondingly weak just at the time when a hot spark is most needed to ignite the chilled and only partly vaporized mixture. An extra charge for twelve hours at a time with a full rate radio battery charger will help to eliminate hard starting. Once every two weeks is sufficient.

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clara teal, BNR an ME, Dh POPULAR SCIENCE MONTHLY ELEVISION pictures which give the impression of depth as well as width are said to have been pro- duced by John L. Baird, pioneer Scotch television experi- menter, by using a stereoscopic receiving set. Behind the spin- ning disk, with its spiral perforations, two pictures appear simultaneously. When seen through two prismatic lenses, the two images seem to combine and give the impression of a solid object. In the United States, an official des- ignation for the area of a single picture in television was announced recently by the Radio Manufacturers’ Association. The word “frame” will be used, as in moving pictures. Each frame is to be scanned in forty-eight lines. The scanning will proceed from top to bottom and from left to right. Fif- Searchlights on Wheels Aid Fire Fighters OODLIGHTING has become a part of fire fighting in Chicago. A new “light wagon,” recently added to the equipment of the city’s fire department, will respond to all important calls, fur- nishing light by which the firemen can work more effectively. Mounted on the top of the truck are a number of large searchlights which can be directed at any angle upon a burning building. Within the truck a large gasoline motor runs the dynamo which generates the electricity used in the lighting, making the apparatus an independent unit in itself. It is believed that this arrangement, by which “all fires will be fought in the daytime,”’ will prevent accidents caused by men stepping into holes in the dark or stumbling over unseen objects. It will also enable fire officials to judge more accurately when burning walls and tim- ber will fall, giving them time to protect their men from such teen separate frames or complete picture area scannings a second will be the standard speed of showing. This decision was reached in an effort to standardize television equipment. Cameraman Snaps Torpedo Diving into Waves IKE a succession of huge flying fish skimming over the water and drop- ping into the waves, a series of torpedoes sped from the deck of one of the latest destroyers during recent tests in the English Channel. A photographer aboard the warship snapped one of the giant missiles as it plunged through the air, obtaining the remarkable photograph that is reproduced below. The vessel is one of several destroyers constructed by a British shipbuilding concern for the navy of Chile. The rapid- fire discharge of practice torpedoes formed one of the concluding tests through which the war vesse] was put before its accept- ance by the Chilean government. danger. English Hard for Parrots ARROTS, tested at the municipal zoo in Dallas, Texas, demonstrated that they could learn Spanish easier than either English or Ger- man. One parrot speaks Spanish words picked up from count- less Mexican visitors and has never spoken a word in English. In El Paso a parrot learned Spanish and Chinese, but seldom spoke English. Remarkable photograph showing giant torpedo an instant after it was shot from the deck of a new destroyer built for the Chilean Navy. Radio Pictures Made Lifelike Apparatus for receiving television pictures in stereoscopic relief being demonstrated by its inventor (standing at right), Gypsum Increases Soil’s Capacity for Moisture AKING land thirsty is the work of, new apparatus developed by th U. S. Department of Agriculture. In th western states some irrigated fields known as hard spots, or hard land, d not absorb water readily. Experiments have shown that irrigation water con taining more sodium than calcium ip creases the hardness of such soil. In other words, “soft water makes hard land and hard water makes soft land.” Gypsum, dissolved in the irrigation ditches, in creased the ability of such spots to absorb water. So experts of the Depart. ment devised an automatic apparatu for adding gypsum to irrigation water, Tribesmen Jail Idols [If Prayers Are Unanswered EN their prayers are not granted, Moroccan tribesmen bind their re ligious images with ropes and leave these fetters on until the desired happening occurs or their displeasure abates, ac- cording to Edward A. Westermarck, noted English sociologist, who has just concluded a study of their ceremonies. A similar instance is reported to have occurred in China in 1888. The man darins of Canton prayed to a god to stop an incessant downpour of rain. When he turned a deaf ear to their pleas, they put the idol in jail. When the ram ceased, they returned it to the temple. Masks Safeguard Health. of Paint Spray Users T LEAST nine tenths of the lead in air containing paint mist is removed by the use of respirators with cotton, paper, or fabric filters, Surgeon General H. S. Cummings announces as the result of experiments by the Public Health Service, in Washington, D.C. The addi- tion of a canister of activated charcoal eliminates most of the solvent vapors as well. These canisters of charcoal may last for weeks, the report states, before the contents become saturated and _ useless. Thg experiments were carried on under conditions considered extreme, high per- centages of paint being in the air.

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scopic ight), soil’s ure vork ofg 1 fields land, do eriments ter con. ‘ium in. In other and and TYpsum, hes, in. pots to Depart- paratus 1 water, is If >red ranted, heir re- re these »pening eS, ac. ‘marck, as just onies. o have > man. god to f rain, * pleas, he rain iple. Ith ) ead in noved otton, eneral [ result Tealth addi- arcoal Ors as re the A bird’s-eye view of the gigantic new highway across the James River. It cost $7,000,000. Begin Search for Diamond Fields in Canada RE there diamond fields in Canada? Not long ago, some diamonds of commercial size were found in Indiana by tourists who examined debris around the rock mounds left in parts of that state at the end of ancient glacier drifts. Dis- covery of this treasure has revived inter- est among scientists in the possibility that there may be diamond-bearing rock in the James Bay region in Canada. The Indiana diamonds are by no means the first to be found in the United States. Diamonds have been encountered in Georgia, Kentucky, Virginia, ‘Tennessee, Wisconsin, California, and Oregon. A crystal weighing twenty-three and three- fourths carats was found in Virginia, in 1855, and one weighing twenty-one and one fourth carats in Wisconsin in 1886. A number of small diamonds were un- earthed near Murfreesboro, Pike County, Arkansas, in 1906. News of the recent Indiana find has re- sulted in exploration in Northern Ontario, but although some small crystals found there have been pronounced diamonds by Dominion mineralogists, their identifica- tion has not thoroughly convinced diamond experts. Even if the stones are diamonds, they are said to be so small as to possess little commercial value. Big Trees, Centuries Old, Found to Be Fireproof ONE of the reasons for the amazingly long life of the California Big Tree, the forest giant which reaches an age of 4,000 and sometimes even 6,000 years, was discovered a few weeks ago. Experi- ments with its bark showed that it has a resistance to fire surpassed only by that of asbestos! Conséquently, the great tree survives the forest conflagrations which destroy its more inflammable brethren. A piece of the bark twelve inches square was put in a wood fire_in a lumber mill and burned for eight hours. At the end of the test, the bark was no more than charred on the outside. POPULAR SCIENCE MONTHLY Five-Mile Highway Built Across James River IHE world’s longest highway bridge, a five-and-a-half-mile span crossing the James River in Virginia, and connecting Newport News, Norfolk, and Portsmouth, was opened to traffic recently. Built at a cost of $7,000,000, the new bridge closes a large gap in the Atlantic Coastal highway and forms a direct road down the historic Virginia Peninsula. The huge span rests on piles which, in many cases, descend 100 feet under the surface of the water. In one spot, the bridge rises to a height of 200 feet above the river, but most of the twenty-three- foot roadway is fifty feet above the water level. The great structure has one of the largest lift-spans in existence, three hundred feet long with a lift of fifty feet, allowing space for even the largest vessels to pass through. The James River Bridge is the only one downstream from Richmond, which is seventy-three miles from Newport News. Together with the two older bridges across Chuckatuck Creek and the Nansemond River, it completes a long-needed link between the Virginia Peninsula and the mainland. Compressed Air Drill New Aid to Surgeons HE pneumatic drill, familiar to en- gineering, is the newest of aids to sur- geons in the operating room. Dr. W. H. Ogilvie, an assistant surgeon at Guy’s Hospital, London, England, is the -in- ventor of the new surgical instrument, pictured below. It is designed for use in difficult bone operations and is con- structed on the same principle as the compressed-air drills used in steel con- struction. The miniature drill is connected with a cylinder of compressed air, which is carried in a holder that rolls on casters. Thus it can be transported readily from room to room. The drill is controlled by a trigger on the “gun grip” handle by which the surgeon holds it. Pneumatic drill for surgeons’ use in bone operations. It is driven from the compressed air cylinder at left. The huge lift span, 300 feet long, raised to a height of 200 feet above the river surface. Your Busy Heart Is Fed by Tiny “Dinner Pails’’ HE adult heart—the only organ in the body whose muscles never rest nor sleep during life—makes an average total of 108,000 beats every twenty-four hours! How does this busy organ find time to “eat” and fortify itself for its arduous labors? It remained for a Japanese scientist, Professor Y. Kato, of the Okayama Medical College, to solve this interesting mystery. Kato, after a long period of investigation, announced the other day that he had discovered that Nature has provided what may be described as little “dinner pails” from which the muscle fibers of the heart—which, indeed, has scarcely time to “eat”—are ingeniously “*fed.”” He studied small fragments of heart muscle under the microscope and found tiny disk-shaped organs between the muscle fibers. He injected chemical re- agents into the blood of animals and, after examining their heart muscles, ob- served that these substances had accumu- lated in the little disks. On these and other facts the Japanese scientist bases his theory that the disks are, in effect, dinner pails, which collect food materials from the blood and pass them around to the heart muscles. Plan World’s Largest Airplane Plant largest aircraft manufactur- ing plant in the world is soon to be built in California, according to a recent announcement by interests that have purchased control of the Fokker Aircraft Corporation. Anthony H. G. Fokker, creator of the ships that bear his name, re- mains in charge of design. Airplanes of all types will be produced in enormous quantities. Already the Fokker plants here and abroad have manufactured 16,000 planes.

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mm ee eee SO Le And Fo eer Tepe rey, (PISS: AR Ae PELLET it lies Sd POPULAR SCIENCE MON THLY At left: The “solitaire’’ tennis device installed on a roof of a building. If the ball is missed it is not lost, for it is fas- tened toaropestretched between the two poles by a rubber band, which snaps it back to the player when hit. Below: This open-air ice skating rink, using the new chemical ice substitute, can be used in summer or winter. Rubber Band Returns Ball In One-Man Tennis WOU can play tennis with yourself by means of a simple, one-man tennis outfit, recently introduced into this coun- try. Smashing lobs and speedy backhand strokes can be practiced in your own back yard without fear of smashing windows or losing balls, the makers of the device point out. A long rubber band with a tennis ball attached to the end is fastened to the center of a thin fiber rope stretched be- tween two tall poles. The ball is put in service in the usual way, and the rubber band speedily returns it each time it is struck. Skill is required to drive the ball at the correct angle to make it return directly to the player at the right height for another drive. Amateur and profes- sional players who have used the device say that it gives valuable training in con- trolling the direction of strokes and also in timing them properly. How the apparatus may be set up on the roof of an office building or hotel is illustrated by the photograph above, in which Wallace Bates, a former tennis champion, and a friend are shown trying out the new device. : Ry eee ping Ry asset 5 eR" ¢ Chemical Makes Open-Air Ice Skating July Sport CE skating in a bathing suit under a broiling summer sun has been made possible by the recent discovery, in Ger- many, of a chemical substitute for ice. When sprinkled over a smooth floor, the chemical immediately hardens into a solid polished surface over which the sharp runners of the skates glide without cut- ting through. This artificial ice will stand high temperatures and can be used in out- door rinks even in the middle of July. Its expense is negligible compared to the up- keep of a skating rink using real ice. A miniature model of the Potsdamer-Platz, Berlin, with tiny automobiles and street cars, is used to teach German policemen methods of controlling the traffic at this and other congested points. February, 19% Air Landmarks Should BR, Yellow, White, Black HROME yellow, white, and dead black are the three best colors for markings to guide aviators, such as tow. ers of transmission lines along an airway and field boundary markers, accord} d Woody Hockaday, Aeronautics Diyig U.S. Department of Commerce, When these three tints are used in combinat to paint stripes upon the landmarks, jj, explained, the white and yellow reflect the light and the dead black provides a gg. trasting background to give high yjg. bility. Beacon sites on Federal airw are fifty-six-foot chrome yelloy arrows made of concrete. Traveling Shears Clear Phone Lines of Litter LEARING telephone and tele. graph wires of kites and othe entanglements has been made easier by the invention of Albert High. tower, a Fresno, Calif., lineman, The mechanism consists of a trolley truck carrying a pair of strong shears operated by a rope and 9% designed that it cannot jump the wire once it is properly mounted, The shears will cut through rope and cloth and will even sever small limbs of trees which sometimes fall across the lines. Shears, slid along the telephone wires on a trolley, cut away rope and other entanglements. Traffic Problems Revealed by Working Models OYS are now being used to teach traffic cops of Berlin, Germany, to do their work more efficiently. Tiny horses and wagons, automobiles, and street cars move along the streets of a miniature model town, part of which is shown in the photograph at the left, while the police- men, under the direction of an expert traffic officer, determine how the little’ control station at the street intersection, should be operated to control the traffic, meeting from five separate streets. Miniature wooden policemen, with their arms indicating “stop” or “go,” are. placed near the control tower to help give, directions. A map on the wall behind the, table gives a bird’s-eye view of the thor-, oughfares of Berlin. Realistic touches are added to the street corner scene in the, model—which, by the way, represents the fameus Potsdamer-Platz—by the addition ; of little trees, lamp-posts, and pedestrians.

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on a nents, led teach to do horses t cars iature in the olice- *xpert little action traffic. ) give. d the, thor- . S are 1 the, s the jition , Tans. pebruary, 1929 POPULAR SCIENCE MONTHLY 61 SelfDumping Scow Turns Somersault in the Water vgs ey eek oe ae eee Thr start of the flip-flop. The loaded scow begins to sink Over she goes! The emptied The scow bottom side up. The water ballast is seen pouring on one side, as the underwater flood tank fills with water. SELF-DUMPING scow that flops over on its back and receives its next load upside-down, is being operated in the Puget Sound by a Seattle, Wash., com- pany. Both the top and the bottom of the scow are identical, so it can be loaded whichever surface is on top. The unusual boat is 100 feet long, thirty-six feet wide, Grafts Part of Human Eye in Amazing Operation fm in 1908, Dr. Hugh Mackay D. awbarn, the famous American sur- geon, saved his son’s life by grafting a large piece of his own skin onto that of the boy’s, the operation astonished surgeons and physicians as well as laymen through- out the world. Since then, many wonderful grafting tions have been performed, but it was left for a surgeon in the New York Eye and Ear Hospital to transplant, for the first time, part of one man’s eye to the eye of another, saving the sight of the latter. The results of this amazing opera- tion, performed a few weeks ago, were re- ported satisfactory. The sufferer in question, an inmate of the Home for the Blind, has one glass eye. The other eye was obscured by a cataract toa point where hardly any vision was left him. This eye was restored by graft- ing upon it the cornea—the transparent part of the coat of the eyeball—from the eye of a patient to whom it had been rendered useless by growth of a tumor. The delicate operation had to be per- formed in record time to prevent the liv- ing tissue of the cornea from dying before it was transplanted to the eye of its new owner. When the bandages were re- moved, the patient’s patched eye was found to have a vision of about ten feet. Catch Birds in Fish Nets ROBABLY the stupidest winged crea- ture is the auk, a small, web-footed, penguinlike bird whose haunts are the Arctic regions. A Canadian zodlogist, re- cently returned from the Far North, de- scribed the catching of droves of auks by Eskimos who were armed only with fish nets! The birds apparently cannot dis- tinguish men from rocks. The scientist estimated that he saw more than 100,000 auks on Hakluyt Island alone. Their behavior, he said, is that of little soldiers on parade. They ad- vance in long straight lines. scow in the somersault. and eleven and one half feet deep. Braced “‘sideboards,” four feet high, keep the load in place while it is being towed. The scow, built of wood, is divided lengthwise internally into two halves, each half containing an air-tight compart- ment and a flood tank operated through two eight-inch valves. On one side the Invents New Front-Wheel Drive for Autos NOTHER attempt to apply the pow- er of an automobile motor to the front wheels instead of the rear has been. made recently by a French automobile engineer, M. Sensaud. In the picture above, the casing of the main driving gear may be seen in the center of the complicated front axle, just below the ra- diator of the automobile. Power is applied to the wheels through a system of gears. The close proximity of the driving wheels to the motor is expected to give greater effi- ciency by reducing loss of power in transmission. Front drive cars frequently have been built and a number have attained prominence on the race tracks, but they never have reached great popularity with the ordi- nary motorist because of the difficulty in steering them. from the flood tank, and the deck is ready for a new load. air-tight compartment is placed above the flood tank, and on the other, below it. A trip rope from the towing tug opens the flood valves on the side in which the flood tank is below the air-tight compart- ment. As this tank fills with water, the greatly increased weight on that side ’ throws the load out of balance and causes the scow to turn completely over. The air-tight compartment, now being on the bottom, raises the flood tank above the water line so that the water drains out as the scow is towed back to its loading berth. A 500-cubic-yard load can be carried by the boat and dumped in this manner. Where Half of the World’s Gold Is Weighed rr A stream of yellow ingots, more than half the gold produced in the world passes through the weighing rooms of a refinery at Germiston, near Johannesburg, South Africa. Unrefined blocks of gold representing a fortune] are piled before the weighing official, who places them in the pans of sensitive scales, operating within dust-proof glass cases. The weight of each is recorded before native laborers carry them to the refining plant. The latest figures available, those for 1926, reveal that the South African mines of the Transvaal produced more than $200,000,000 worth of the precious min- eral during that year. The total produc- tion for the world was valued at less than $400,000,000. Of this amount, the mincs of the United States yielded slightly more than $46,000,000, Weighing blocks of gold, each worth a small forture, on delicate scales in the refinery near J Africa.

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Ot aT, Eee Al eR Se 62 New Hand Truck Picks Up Piles of Boxes Y PICKING up two stacks of boxes at a time, a new hand truck, invented in England, saves time by doing away with the necessity of loading eac1 box on the truck separately. After the truck has been run into position, the wheels are held from rolling by application of a foot- brake. A hand lever then operates a pair of clamps at the front of the truck, causing them to grip the boxes at the bottom of the piles. The body of the truck, slightly wider than the two columns of boxes, holds the upper boxes in place while they are being wheeled. At the destination, the clamps are released and the boxes discharged in a neat pile. Principle of Range Finder Applied to Depth Gage HE principle of the range finder, used in war time to determine the distance of ships and airplanes, can be applied to a special form of microscope and em- ployed in the laboratory for minute and. accurate depth measurements. This was demonstrated recently by Dr. I. C. Gardner, of the United States Bureau of Standards, before the American Optical Society. He showed that the range finder con- sists of two telescopes with their main lenses some distance apart, but with their prisms arranged so that the observer sees the view through both telescopes at the same time. He sees the scene in circular form, divided across the center. The “Beams” of Sound to “SOUND searchlight,”’ described as throwing out a concentrated “beam” of sound that penetrates high into the air, as a shaft of light cuts into the dark- ness, was tested recently at Camden, N. J. The device is expected to prove valuable in directing aircraft to landing fields dur- ing fog, when they have approached so close that the radio beacon has become ineffective. The so-called “super-directional” horn was developed by S. T. Williams, of the Victor Talking Machine Company. It consists of a cluster of nine conical horn units each carrying a loudspeaker. They are joined into a single straight-sided mouth, forming a rectangular box about eight feet square and twenty feet long. This box is mounted on pivots which, in POPULAR SCIENCE MONTHLY A pair of mechanical arms, operated by lever, grasp the bottom of the double pile of boxes. upper half is the view through one tele- scope, the lower through the other. When the prisms are so adjusted that the object being measured is not split in the center, the actual distance may be read off a dial. Now, the depth gage applies the identi- cal principle, but two microscopes, in- stead of telescopes, are set at an angle of twenty-five degrees, so that both can be focused upon the same spot. The field also is divided, and when the instrument is set so that no break occurs, the depth can be measured to an accuracy of about one-ten-thousandth of an inch. Guide Aircraft in Fog combination with the wheeled base, allow it to be pointed in any direction that may be desired. During the test, the horn was mounted on top of a ten-story building and trained on the U. §. Army dirigible J-4, which circled overhead at an altitude of 1,500 Left: The “sound searchlight’’ talking to the crew of the U.S. Army dirigible J-4, 1,500 feet up in the air. Above: A unit of the great loudspeaker horn. February, 19y feet. : Officers of the airship re ' could hear every syllable of the dist spoken to them by men on the roof he Further tests probably will be carried! soon with the Navy’s rigid ding) Los Angeles. A giant phonograph, thirty-one | tall, which could be heard thirty } away, was built by the same com not long ago and described in Pop Science Montuty. The unique fey of the new horn, which makes it an vance over the stentorian phonogm according to the inventor, is that ity centrates the sound waves insteg allowing them to scatter. Thus, the “beam” can be trained upon an ¢ high in the air and, like a searchlight, follow its flight. Guide ropes manipulj from the roof tilt the horn up and and from side to side. 4 Speeding Typists’ Fingers with Radio “Jazz” ~ A PSYCHOLOGIST connected withy Pennsylvania college not long @ conducted an experiment in which typi with their typewriters, kettledrums, sagp phones, and plain, everyday pots and pans were used to prove his contention that human beings work better and faster amid the din produced by modern ip. dustrial centers than in solitude and quiet surroundings, as generally believed, He placed a dozen typists with their machines in one of the classrooms and bade them start a certain piece of work. After recording the time required to com- plete the job, he asked them to repeat the process. But this time a score of students with a variety of noise-making instn- ments were ushered in and began to make an ear-splitting din. The girls not only finished the piece of typewriting in shorter time, he announced, but also with fewer mistakes! The same idea seems to underlie the recent action of the officials of the Brooklyn, N. Y., plant of the Bush Terminal Company, who have had a radio installed in the main office. The tuning-in of any feature is permitted dur- ing working hours, but jazz music is given the preference, because, as one of the officials puts it, “it makes the typists’ fingers move faster!” Screen Production Shows Motion of Planet UR neighbor planet Jupiter took the leading réle, the other night, ina remarkable motion picture thrown on the screen in Washington, D. C. By an it- genious process, similar to that used in photographing budding flowers, its mo tions were so sped up that spectators saw Jupiter actually revolving, and one of its satellites or moons produce an eclipse before their eves. According to a plan worked out by Dr. C. E. K. Mees, of the Eastman Kodak Company Research Laboratory, succes sive exposures were made at regular in- tervals several minutes apart, on two or three nights. Then they were run off at standard movie speed, thus accelerating the motion enough to make it plainly visible. The pictures were taken by Prof. WeH. Wright through the telescope of the Lick Observatory.

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10WS ook the at, ina 2 on the y an in- used in its mo- ors saw 1e of its eclipse by Dr. Kodak succes- ular in- two or n off at erating plainly ry Prof. e of the februarys 1929 This spectacular night photo shows a 750,000-volt flashover jumping in- qiators in brilliant lightning forks. Tractor Sets 1,330-Mile Endurance Record LODDING along like the tortoise in the fable, a tractor, pulling a disk harrow over a thousand-acre field in California, set what is believed to be a world’s record recently when it kept going for seventeen nights and days. The test was made by engineers of the University of California. During its long mn, the tractor covered 1,330 miles and disked 1,280. acres. The only times the wheels stopped turning were for short periods four times a day when the tanks were filled with gasoline and oil. The motor was not stopped. The only mechanical difficulty en- countered was the loosening of a valve push rod. ‘This was adjusted without stopping. The fuel consumption was 1,1511% gallons; oil, 11714 quarts. Walls Hide Radiators in Novel Heating System MALL hot water pipes, buried in walls, ceilings, and floors of the new British Embassy, under construction in Washington, D. C., will furnish a novel heating system that eliminates the use of visible radiators. ‘This is believed to be the first time the system has been installed in a building in this country, although frequently used in England. In some of the rooms all four walls and the ceiling will be warmed. In others, heating the floor is expected to make the room comfortable. The British officials in charge of the construction decided against the familiar radiator, which has been widely employed since it was invented in 1885, on the ground that it takes up too much space and gives a less uniform heating to the room than a system of invisible pipes. POPULAR SCIENCE MONTHLY Left: An electric field as re- vealed by the camera. Tiny silk threads show lines of force. Electric field around insulator in glass tank being photographed. 63 Invisible Forces Photographed! : T photographs of the : electric field around a con- ductor, made at Purdue Uni- versity, promise to simplify enor- mously the problem of designing good high-voltage insulators and to aid in the study of what happens around a wire carrying electric current. They make it possible to see the direction of electric lines of force in the air that precede lightninglike discharge of sparks, replacing tedious calculations. This “electric field” is normally invisible; but the investigators found that when they placed an electric cable or insulator in a glass tank filled with carbon tetrachlo- ride, a transparent nonconducting liquid, and floated thousands of tiny shreds of artificial silk in it, the silk threads immediately lined up to give a perfect picture of direction of electric stresses. At the same time they showed along what path the current was most likely to jump off or to break down insulating material. A camera, set up over the tank, took pictures that will aid in making improved cables and insulators. Bolstering Up the Leaning Tower of Pisa the foundation of the leaning tower of Pisa in Italy, in an effort to save the famous medieval structure. The tipping of the tower has _ increased steadily, and fear was felt for its safety. When measured a hundred years ago, the tower was fifteen and one half feet out of the perpendicular. In 1910, it (Cris foonds is being forced under i gt . aly Tee. Workmen are seen here forcing concrete under the foundation of the leaning tower of Pisa,.in an attempt to prevent its collapse. was sixteen and one half feet. The foundation descends only ten feet into the ground. A recent survey was made of the subsoil underneath to see what strengthening measures could be under- taken. It was decided to force concrete under the walls, which are thirteen feet thick at the base. The tower, with its eight stories, rises 179 feet, and is constructed throughout of marble. Experts who have studied it believe that the tower assumed its leaning position while under construction, early in the twelfth century, and that its de- signers did not intend it to lean. Tests Show Canary Bird Is Best Gas Detector HE United States Bureau of Mines, after experimenting with chickens, rabbits, dogs, mice, and other animals, has reached the conclusion that the canary is the best detector of poisonous gas in mines. In this connection, it will be remembered that Dr. Hugo Eckener, builder and commander of the Graf - Zeppelin, had his pet canary aboard for this purpose when the world’s largest dirigible made its recent trip from Ger- many to America and back. The canary’s fitness for the job lies in the fact that it falls from its perch the moment it breathes dangerous gases, but revives quickly when brought into the fresh air. It seldom dies from the effects, and can be exposed and revived many times within a short while without harm. In the Bureau of Mines test, cana- ries, white mice, chickens, dogs, pigeons, sparrows, guinea pigs, and rabbits col- lapsed in the order named when breathing a small amount of carbon monoxide.

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HE two men in the seat behind me were having a hot argument. “You sure gave me a bum steer when you recommended that Jemon,” one of them growled disgustedly. “About all that aHeged radio set has is a swell cabinet. The rest of it’s a bunch of junk!” “Junk nothing!” asserted the other man heatedly. “My set works fine, doesn’t it? How can your set be junk when it’s exactly like mine? You must have a bad tube or something.” The man with the grievance laughed sarcastically. ‘“‘ Yeah,” he gibed, “‘it must be something, all right, but it sure isn’t a bad tube. If all the tubes the dealer has tried in that set were laid end to end they’d reach from here to the middle of next March! Theset’sa flop, I tell you!” I lost the rest of the conversa- tion, for the train stopped just then and the two men got off. However, it’s pretty safe to prophesy that the disgruntled chap will finally trade in or other- wise dispose of the unsatisfactory set and get another. And the new radio receiver undoubtedly will be of a different make than the old one. Now what brought about this un- fortunate incident? The fact that the two sets appeared to be identical would lead one naturally to believe that they should operate alike. Why, then, did they perform differently? | mh a articles in PopuLAaR . Scrence Monrtuty have pointed out that location is all-important. A set that gives excellent results in one locality may not do nearly so well in another place only a short distance away. Every radio fan who has moved several times can testify to the variation in reception. But aside from locality, there are other iraportant reasons why radio sets that appear to be identical are not alike in performance. | The condition of the vacuum tubes in any set is so important that almost the first thing the service man does when he is called in to remedy trouble is to test the tubes. Obviously if one of two iden- tical receivers is fitted with one or more tubes that are below par, and the other receiver has good tubes in every socket, there will be a great difference in results, *. POPULAR SCIENCE MONTHLY Sets May Look Alike, But Behave Differently By JOHN CARR But even if the two receivers were fitted with good tubes, one of them might be, and often is, inferior as to sensitive- ness and selectivity. Sometimes there is a pronounced difference in tone quality. The chief cause of such inferiority is lack of synchronization in the tuning of the radio-frequency stages. This _ breath- taking mouthful of words means, in plain language, that the parts of the poor re- ceiver are lacking in “teamwork.” In- dividually they may be stars, but col- lectively they don’t work together. You know, of course, that the weak radio impulse that reaches your set by way of the antenna is amplified or strengthened many times before it is con-

Even a slight flaw or a faulty adjustment in the plates of one of the condensers may result in inferior broadcast reception. verted into the electrical equivalent of sound that you can hear. This strengthen- ing of the radio signal is accomplished by passing it through several circuits, each of which consists, essentially, of a vacuum tube, a coil of wire, and a queer-looking metal gadget with two sets of metal fins, called a condenser. You have noticed how some of these fins slide in between others without actually coming into con- tact, when you turn the knob that tunes the stations. Moving these fins, or con- denser plates, governs the tuning of the individual stage of amplification. The same result_could be obtained by chang- ing the number of turns in the coil of wire, but it is mechanically more convenient to do the tuning by moving the condenser plates. OW when the parts of a radio receiver are not doing good teamwork, it simply means that the condenser plates are not all producing the same effect for any given amount of movement of the tuning control knob. Sometimes the fins are not set at the same angle on the shaft, but more often the space between the moving fins or

February, 19» ”

plates and the stationary ones is different in the different condensers. It takes only a slight error to cause trouble. The tiniest dent in one plate may be just enough to throw the tuning of that stage out of line with the other stages and result in cutting the sensitiveness of the receiver in half. And because the selectivity of g radio receiver, which is its ability to choose between stations, depends on the cumulative effect of several stages, this desirable quality may be seriously im. paired. | F COURSE, defects in the condensers are not always to blame for poor teamwork. Any irregularity in the wind. ing of the coils will cause the same trouble, For really satisfactory results, therefore, both the coils and the condensers must be manufactured with great accuracy; and since it would be extremely expensive to make them to precision standards, absolutely alike, some provision must be made for ironing out the slight differences after the set is fully assembled and ready for use. [ And here is where mysterious differences occur. One set may be adjusted to get teamwork out of the parts, and another may not. The adjusting must be done by ke skilled workmen, and with radio be sets selling at the prices that pre- " vail this year, there naturally exists a temptation to slight this expensive but necessary adjustment. In fact, several makes of receivers have failed to pass the tests of the Popular Science Institute of Standards because they were carelessly assembled. RADIO receiver is, after all, merely a piece of apparatus made of aluni- num, brass, copper, iron, and various insulating materials, the total value of ¥ which as raw material is but a tiny b fractionj of its selling price. The re- ¥ mainder of the money that you spend ? pays for the manufacturing of this mate- P rial into finished parts and for the hand- work necessary to put these parts to- gether properly and adjust them. Now what can be done to make the parts do good teamwork if they are not working together? You, as the owner, can’t do a thing about it unless you have a pretty fair understanding of the opera- tion of each part. Lacking that knowl- edge, any “fiddling” you may do with the adjustments probably will result in making matters worse rather than better. And there is the chance, also, that the real rouble may be merely a matter of locality or poor tubes. te = | er ee ed

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‘different akes only le. The be just hat stage nd result FeCeiver vity of a bility to IS on the ges, this usly im. ndensers or Poor 1€ wind. trouble, results, and the actured Since it sive to ndards, “OVision out the 2 set is for use. terious may be out of Ly not. me by 1 radio at pre- turally it this .. s have opular Cause rely a lumi- arious ue of tiny e re- spend nate- 1and- s to- 2 the e not vner, have pera- 10wl- h the t in tter, . the or of F YOUR present battery receiver is of comparatively recent make and gives good results, revamping the outfit along modern lines may well be worth while, if you enjoy working with tools. POPULAR SCIENCE MONTHLY Rewiring for A. C. Simplified Here You Can Learn When It Pays to Discard Batteries, and How to Change the Old Radio Set into an “Electric” HOUSANDS of radio fans now are trying to decide what to do about their battery operated radio receivers. They ask: ‘Shall I get new batteries and keep on using my set as it is? Had I better scrap it and get a new electric model? Isn’t there some way to make it over so it will be an electric?” And the correct answer, curiously enough, may be either yes or no to any one of these three typical questions. It all depends on the particular set and the individual who owns it. For instance, the receiver may be a very old one, poor in tone quality and obsolete in appearance. In such a case I would unhesitatingly recommend keeping the set just as it is until you can afford a whole new outfit, then scrap it and either buy or build a modern receiver. Don’t waste time trying to revamp a really old receiver along modern lines. It doesn’t pay. Too much has to be done to it. On the other hand, the receiver may be of comparatively recent make and give its owner satisfactory results for distance, volume, and tone quality. In that case revamping the outfit along modern lines may be worth while or it may not, de- pending on the owner’s ability to do the work involved. Of course this problem cannot confront the man who lives where there is no elec- tric light current. He must, perforce, be content with battery operation. Don’t expect to improve the operation of your radio set by rewiring it for full electric operation. A full electric set is By ALFRED P. LANE neither more sensitive nor more selective than the same set operated by batteries. The tone quality will not be changed, but if you have been operating the set on ninety volts with 201-A tubes in all sock- ets, you can greatly increase the volume on local stations with good tone quality by using a power tube type 171-A in the last audio stage. If your receiver is now equipped with a 171-A tube in the last stage, its operation after rewiring for alternating current tubes should be as good but no better than the results you now obtain from batteries. Certain types of radio receivers, either because of the circuit employed or the tubes for which they are designed, are not good subjects for A. C. rewiring jobs. Among these may be listed practically all types of reflex sets and superhetero- dynes designed for use with the 199 type of tube. The simplest way to obtain full electric operation with such receivers is to use an approved type of A and B eliminator. And the reflex circuits may give trouble even with eliminators. EWIRING for full electric operation with the modern A. C. tubes is most successful with the various types of tuned-radio-frequency and neutrodyne receivers, provided they are not fitted with resistance coupled amplifiers. It is, of course, possible to operate a resistance coupled amplifier circuit with alternating current, but the simple circuit here described cannot be used. If you have a set using resistance coupled amplifiers, I would recommend changing over to trans- former coupled audio amplification so that you can use the methods outlined on these pages. Modern transformer coupled audio amplification will give practically as good tone quality as resistance coupling, and the principal advantage of resistance coupling, low B-current consumption, is of no importance in full electric operation. HERE are many types of tuned- radio-frequency circuits, but they all boil down to a circuit similar to the one shown in Fig. 1. They may have fewer rheostats or even no rheostats of the hand adjustable type. The coils may be of different design, and there are many forms of balancing or oscillation control. The condensers may be lined up on a single control or they may be fitted to individual dials. The receiver may have six tubes instead of the five shown or it may, in the case of many home built re- ceivers, have only a single stage of radio- frequency amplification. These matters do not concern us in our rewiring job, for the method we will follow will work no matter how these details are arranged. First you must get the necessary apparatus to perform the rewiring job. Here is the list: A filament-heating transformer having three secondary windings giving 1, 21%, and 5 volts. The 24%- and 5-volt windings must be center-tapped. A high grade factory built or home assembled B-eliminator. (If you already have a B-eliminator that works well you

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66 will not have to purchase another.) A socket for type 227 tube (five-prong). A six-ohm potentiometer (P in Fig. 2). A wire wound fixed resistance (R/ in Fig. 2. The -value in ohms of this resist- ance is determined by the number of 226 tubes in the circuit). A wire wound fixed resistance (R2 in Fig. 2). A high resistance, noninductive, non- capacitive potentiometer (V in Fig. 2). A one-microfarad by-pass condenser (use as explained below). A supply of wire. Ordinary double cot- ton, paraffined bell wire will do, but the regular insulated radio hook-up wire is much better. feo first job in the rewiring is to determine which tubes are connected in the various stages. If the receiver is home built, you can settle this question by referring to the diagram you used in wiring it. If it is a commercial set, there probably will be marks on the subpanel near each socket that will give you the desired information. The markings are abbreviated to “ist RF”, “2nd RF,” “Det,” “‘1st AF,” and so on. In any case your job is to locate the detector socket and the second or last audio socket.. Sometimes, instead of marking the stages, the type numbers of the tubes which should be used are indi- cated. If the set is arranged for a type 171 tube in the last socket, there will be some marking to indicate this fact. The detector socket always can be identified by the grid condenser and grid leak, which always are connected as close to the grid terminal of the socket as the arrangement of the apparatus will permit. The grid condenser is a small fixed con- denser fitted with clips which hold the tubular grid leak. EN you have definitely located the detector tube socket, replace it with the five-hole socket, as shown in Fig. 2. Note that the connection to the grid condenser and that to the P terminal of the first audio transformer are simply removed from the old four-hole socket and attached to the similarly marked binding posts on the new five-hole socket. POPULAR SCIENCE MONTHLY Fig. 1. This wiring diagram shows a quency circuit. The diagram in Fig. 201A G P we for A. C. operation, whether your set has more or fewer tubes, 4 typical tuned-radio-fre- 2 shows how to rewire ae al +C -5 carefully comparing the wiring in your receiver with Figs. 1 and 2, you will see how to do this. The next step is to cut away all the filament wiring from the sockets. It is not necessary to remove this wiring from the receiver. In fact it should be left in place. Merely clip each wire at the socket terminal and then clip off a short piece of it so that there will be no chance of the loose end making an accidental contact. Also make sure that the wires will not sag and short circuit against some other wires in the set. OW connect two long pieces of wire to the two H terminals of the new socket you have installed for the detector tube, and twist these wires together like an ordinary twisted electric light cord. The other ends of the wires should be con- nected to the 214-volt binding posts on the filament heating transformer, as shown in Fig. 2. Repeat the same operation for the socket that takes the 171A power tube, the last audio socket. As shown in Fig. 2, this twisted pair is connected to the 5-volt binding posts on the filament-heating transformer. In the diagram of Fig. 2 there are three sockets marked for 226 tubes. In your set there may be only two if the set has only one stage of radio-frequency amplifi- cation (the usual four-tube set), or there may be four or even five if the set has a total of six or seven tubes. It makes no difference wl ? and bake 90V -40C 1wOyV of the filament-heating transformer, ag shown in Fig. 2. This completes the actual filament wiring. You can check your work up to this point by inserting the tubes in the sockets and putting the plug from the filament-heating traps. former in the nearest electric light socket, The next step 1s to connect the minus-4 and plus-A binding posts together witha piece of wire. Then mount the poten. tiometer P at any convenient point back of the panel and connect the outer termi- nals to the wires leading from any socketin which a 226 tube is to be inserted. Be careful that you do not connect both wires from the potentiometer to the same socket wire. It is easy to make this mistake because the wires from the sockets are twisted together. Now connect the center terminal of the potentiometer to one end of resistance Ri, This resistance should have a value of 1,000 ohms if there are two 226 tubes in the receiver, 700 ohms for three 226 tubes, or 500 ohms if there are four 226 tubes. The other end of resistance R1 should be connected to the original filament wir- ing at the nearest convenient point. THERE are only two 226 tubes in the set you may be able to get by without any by-pass condenser across R1, but if three or more 226 tubes are in the set you must use a one-microfarad by-pass con- denser connected directly across the terminals of Ri. Febru Now connect one end of resistance R2, which should have a value of 2,000 ohms if one 171A tube is used, to any conven- ient point on the original filament wiring. The other end of resistance R2 should be connected to the center terminal of the five-volt winding on the filament heating transformer. The two resistances Ri and R2 are required to supply the necessary | C-bias voltages on the radio- and how many 226 tubes there are. They should all be wired in parallel and connected to the \y 114-volt binding posts: ’ \Y Run a wire from.the terminal of the new socket marked K to the nearest point on the wire leading from the metal frame of the variable condenser that tunes the detector circuit. By x x NB 226 : 6 x Ds we Oe! 226 nes 227 —_ MAG p G 6) HM - >> Wy a) | audio-frequency amplifier tubes. In some receivers, the F termi- nals of the audio-frequency trans- formers are connected to binding posts so that C-voltage may be applied. The diagram of Fig. 1 shows this arrangement. On other sets not using a C-battery, the F terminals of the audio transformers are connected to the minus side of the filament wiring. As shown in Fig. 2, Z the F terminals are connected to the old filament wiring at the nearest point. there is any doubt about which are the F terminals, the same result can be accomplished by (Continued on page 149) @) +A walk “dake Fig. 2. Heavy black lines show the new wiring for A. C. operation. Fixed resist- ances, if needed, are put in at points X. tn ‘ae i 6) ee ee

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1eTs 2 of old If the 49) POPULAR SCIENCE MONTHLY 67 Timely Hints for the Radio Fan A Useful Transformer Test Headphones Aid in Fixing Position of Instruments to Avoid Coupling Trouble—Measuring the Life of a Storage Battery HE audio transformer, as every radio experi- menter knows, consists of a metal core made up of many layers of thin trans- former steel on which are wound the primary and _ secondary windings. And there is no dif- ference in principle between an audio transformer and the power transformer used in the modern electric radio receiver. All alternating current trans- formers operate by electromag- netic action. In use, the core of the transformer is surrounded at all times by magnetic lines of force. Of course, with the usual closed core type of transformer, this external magnetic field is relatively very weak, but in the sensitive circuits of the audio amplifier end of a radio receiver, these weak external fields may cause considerable trouble. There is even more chance for trouble in the modern full electric radio receivers, especially if the external field of the power or filament-heating transformer is acting on the core of one or both of the audio transformers. In such a case there will be a noticeable hum from the loudspeaker no matter how carefully the other parts of the circuit are worked out. The rule-of-thumb method of set- ting audio transformers so that they will not couple together is to place them with the cores at right angles. This rule is a good one, and so is the caution to have the transformers as far apart as the layout will permit. However, there is a_ simple method by which you can find just how to set any two transformers so that there will be no interaction between them O APPARATUS is required except an ordinary pair of headphones. Assuming that you have 110-volt alter- nating current available, connect the ends of a drop cord to the primary wind- ing of one transformer and insert the plug in the nearest electric light socket. Then connect the tips of the headphone cord to the primary or secondary ter- minals of the other audio transformer. Now place the two transformers close together and you will find that you can hear a noticeable hum in the headphones. The illustration on this page shows a test of this kind being carried out in the laboratory of the Popular Science In- stitute of Standards. As you move one or the other of the transformers you will notice that the intensity of the hum changes, and you Using headphones to determine for transformers where the hum disappears. Positions will be able to find several positions for the transformers where the hum entirely disappears. Of course the advantage of making such a test is that you can place the transformers so near each other that they are almost touching, and yet have no interaction. The same method can be followed to find where to place audio transformers so that they will not be affected by the power or filament-heating transformer. Simply plug the power or filament-heating transformer cord into the light socket and connect the headphone cord tips to the audio trans- former. In fact, this method will A B C’s of Radio HILE alternating current operation, as compared with battery operation, affords no better results in the radio-frequency detector, and first audio stages of a receiver, it is a big help in the last audio stage. Working from an alternating current source, you can easily obtain the necessary high B- voltages required for best results when you use modern power tubes. And these tubes definitely improve tone qual- ity, especially when you want plenty of volume. Of course, any desired B- voltage can be obtained from B-batteries if you use a suffi- cient number of them con- nected in series, but this becomes an expensive method if you go beyond 180 volts. prove useful at many points in laying out apparatus for home constructed radio receivers and power or B-eliminator units. Au- dio-frequency choke coils, for instance, can be so placed in a B-eliminator circuit that there will be no interaction to reduce their effectiveness in filtering out the alternating current hum. You can apply 110-volt alter- nating current to the primary or secondary of any audio trans- former or to the terminals of any B-eliminator choke coil without danger of burning out the winding if the terminals of the remaining winding are left unconnected. A piece of wire connected across the terminals of one winding, while 110 volts alternating current is applied to the other, will result in a burn-out, of. course. When Batteries Play Out N OUTSTANDING characteristic of the lead-acid type storage battery as used in all automobiles for starting and lighting, and as the A-battery to supply filament current for a radio receiver, is the remarkable service it gives while it is reasonably new. It will stand around for weeks at a time partly charged and, perhaps, with the water level below the tops of the plates, and yet give good service. The day of reckoning comes rather suddenly. Some evening the radio goes dead, and you discover that the battery is completely discharged. Then, after you give it a long charge, it works well for a time, when the same thing happens again. From then on, life seems to be one continual round of having the battery charged and having it go dead just when you want it most. The useful life of any storage battery is governed by the care you give it. It may last less than a year, or it may give four or five years of good service. But no matter how careful you are, it won’t last much longer than five years. When a battery must be charged every two or three days even when not used, it has outlived its usefulness and should be replaced. No amount of charging or attention will bring a decaying storage battery back to life again. To prolong the life of your storage A-battery, do not let it become dis- charged below 1,200 on the hydrometer. It is better to give it a small charge once a week than to let it go two weeks be- tween charges.

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SE a ae TEP eee: ee ee Se Se ce ma.) Co nd ee a a i np Fabricated Lumber Cut in Labor-Saving Shapes 45 Y cut a tree to pieces and then pay a carpenter money to put it together again?” That is the pertinent question put by Ross Houston, veteran lumberman of Tacoma, Wash., who recently developed and patented a unique labor-saving plan for sawing logs. His system produces “fab- ricated”’ or shaped lumber instead of flat boards and square beams, now the stand- ard product of lumber mills. Just as steel girders are formed for convenience in “I” and “T” shapes, Houston cuts boards in one-piece slabs in L’s, X’s, and T’s—each for a special purpose. He claims striking economies for his solid lumber shapes. For instance, the post at the corner of an ordinary dwelling is usually made, today, by nailing together three two-by- fours. The Houston house corner, a solid beam with a cross section resembling a humped letter “L,” has ample nailing surface but contains a seventh less lumber. That means a saving of wood and of freight charges, besides eliminating the usual nailing. A window frame now requires eight pieces of lumber and as many outside joints; but four of Hous- ton’s “L’s,” without outside joints or Stunning Gowns of Metal Soon May Be the Style F EXPERIMENTS made recently by German manufacturers prove prac- ticable and popular, women soon may go to dances and the opera in stunning eve- ning gowns of metal, while their escorts will be clad in a modern adaptation of the suits of armor worn by knights of old. Flexible fabrics containing layers of metallic foil have been perfected; and the next step, the German experts declare, will be the making of clothes of aluminum —-waterproof in wet weather and heat- proof in summer, like the aluminum paint on the exterior of a Zeppelin dirigible. Thin sheets of aluminum, resembling tin foil or gold foil, are coated on both sides with protective material not unlike the plastic substances used in manufac- turing rayon. This fabric is said to be almost as light as silk, tough as leather, waterproof as rubber, and bright and heat-reflecting as aluminum. Of this material, raincoats, umbrellas, and even dresses and business suits may be made. Not only striking frocks for women, but also beautiful effects in household decoration will be obtainable in the new fabrics, the experimenters predict. POPULAR SCIENCE MONTHLY Samples of light structural framing and trim of shaped one-piece lumber. Installing one-piece fabricated partition tee. Insert shows cross section of house corner. nailing, suffice. Other shapes are con- veniently adapted for partition tees, table tops, fence caps, and crates. There are four hundred possible shapes so far. The inventor plans to introduce his new system in lumber mills throughout the country. The one-piece slabs, he says, are as strong as nailed shapes and do not crack or warp. Profits from use of his labor-saving material, Houston says, offset many times the slight added cost of making it at the sawmill. The secret of its manu- facture is simple. Sawing at angles into a log, instead of straight from the side, February, 199 This special “loom” makes flooring out of waste strips left from cutting the new lumber, gives the whole variety of shapes. The corner post is made by setting the says at right angles to each other. Houston has worked out diagrams showing how to get the most in shaped lumber out of a single log. He even sayes the waste, thin half-round slabs left from the cutting. They are slit into narrow strips and glued together to make flooring material on a special “loom” or gluing press that he has invented, capable of turning out 150 feet a minute. ** Lightning” in Auto Motor AGGED forks of miniature lightning flash in the cylinders of your auto- mobile every time an explosion takes place. This was revealed by recent ex- periments conducted in the Aeronautic Research Laboratory of the Massachu- setts Institute of Technology, Cam. bridge, Mass. The action that takes place within the cylinder of a motor when the gas explodes was observed by the experimenters through a thick piece of fused quartz, fixed in a plug in the cylinder. They re- port that the action takes place in three “‘acts.” First there appears the bluish light of the sparks, then the jagged flashes, and finally the brilliant glow of the gas explosion. He Built His Own Castle—On the Ground PRIVATE little castle, complete with towers and battlements, as well as a conservatory for raising flowers dur- ing winter months, has been constructed by T. Martin, a chauffeur in Hookwood; Surrey, England. During a period of un- employment, he planned and built the unique dwelling, making with his own hands all of the concrete blocks which went into its walls. It took eleven months to complete the imposing structure, from the foundation to the finishing touches on the conservatory. The unusual building, patterned after medieval architecture, has been given the name of “Hookwood Castle” by people living in the vicinity. sa 4 4 e ig 4 t i The builder is seen at the right putting the finishing toffches on the glassed conservatory of the remarkehle little castle he constructed with his own hands. He did the job in eleven months. — fe er =m wet elUcrmwtlUromelUCUOllUrlCUwS

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Z out of w lumber, DES, the Saws diagrams n shaped Ven Saves left from > Narrow e flooring or gluing pable of Motor ightning ur auto. n takes cent ex. ronautic ssachu- , Cam. ‘hin the xplodes nenters quartz, hey re- n three bluish jagged zlow of id which nonths , from hes on ilding, re, has <wood inity.

February; 1929 New Experiment Confirms . Findings of Einstein ROF. A. A. MICHELSON, Univer- sity of Chicago physicist, has just ted his memorable experiment of forty years ago, which later served as the hacig of the much-discussed Einstein theory of relativity. The results, recently announced, completely confirm the test he then made with the aid of the late Prof. Edward W. Morley. The Michelson-Morley experiment, which has been the subject of the most heated scientific controversy, was intend- ed to discover whether there exists a hypothetical “ether,” through which the world moves. ‘Two beams of light were made torunarace. They were shot out at right angles to each other, reflected back to their source, and their arrival timed. Had one beaten the other, an “ether drift’? would have been proved, but a “dead heat”’ which actually result- ed could not be explained until Einstein proposed his remarkable theory. New experiments conducted on Mount Wilson, Calif., with instruments ten times as accurate as the first, vindicate both the former experiment and Einstein’s find- ings. That Einstein was fortunate enough to make a correct theory grow from wrong assumptions at the begin- ning, is Prof. Michelson’s conclusion. Amazing Machines Do Work of an Office Force N ALMOST complete “automatic office force” was included in exhibi- tions at the National Business Show, held recently in Chicago. One electric typewriter can be set copying an original letter and will keep on turning out dupli- cates until stopped. Among the auto- matic calculators were machines that subtract, multiply, and check their an- swers, and an amazing apparatus said to solve problems in algebra, geometry, and trigonometry. A mechanical clerk posts ledgers and statements. Suspended by Crane, House Rides across River OUSES have been carried down streets and across bridges in odd moving jobs, but it remained for a Dutch contractor to accomplish the amazing feat of carrying one bodily across a river. He succeeded in lifting a Rotter- dam bungalow with POPULAR SCIENCE MONTHLY a huge floating crane and ferrying it across the River Maas to its new location without injury. Extreme care was re- quired to keep the house from breaking apart. The structure was firmly braced with cross girders, two of which, fastened above the roof, served for anchoring lifting cables. Put Milk in the Dark to Keep It Fresh XPERIMENTS by the Bureau of Dairy Industry of the U. S. Department of Agriculture show milk must be kept in a dark place to retain its flavor and freshness. When exposed to sunlight, milk quickly develops “‘a jlinseed oil odor and a cardboard taste,” the chem- ists found. This is because the light acts as a catalyst, causing oxidation. Of duplicate milk samples used in the test, those kept in the dark developed no off flavors or odors, even after seven to nine days, during which they remained fresh at a near-freezing temperature. Samples kept at the same temperature in sunlight developed unpleasant smell. Handy Radio Aerial Mast Clamps to the Roof ESIGNED to clamp on chimneys, around gutters and eaves, on apart- ment house parapets, or on window sills, a new radio aerial support has been put upon the market. Instead of nailing sticks to the roof or 69

**Fountain Pen’’ Pistol Can Shoot Deadly Bullets “FOUNTAIN PEN” that spurts LA. thirty-eight-caliber bullets was picked up near a street corner in New York City recently and turned over to the police. The tiny weapon, little longer than the width of a man’s hand, is shaped to ap- pear merely a harmless writing instru- ment. A few feet away, it would be mis- taken for a real pen. Only when it is examined closely does the open muzzle at one end reveal its. dan-

fastening them to the chimney to hold up zrials, radio owners can save time and trouble, says the in- ventor, by use of the new clamp, which sup- ports an upright metal rod surmounted by an insulator. When the support is screwed solidly in place, a sec- ond insulator for the vrial “lead-in” can be inserted in a threaded hole in the side.

gerous character. A comparison between the dimensions of the strange weapon andthe mis- sile that it shoots is being made by the two officers in the picture. The pistol unscrews in the middle to insert the cartridge. It is fired by pressing a small button, about the size of a pinhead, in the end of the weapon. This releases a spring that operates the firing pin. Urge Metal Storage for War Needs HE ancient Assyrians

How the floating crane picked up a bungalow and carried it across the Maas River in Holland. Steel cables from the crane were fastened to cross-girders attached above the roof of the dwelling. The aerial mast clamped to peak of garage roof. the lead-in insulator attached. stored huge quantities of iron in times of peace to have a plentiful supply for the manufacture of arms to be used in their frequent wars. A similar method is advocated by U. S. Army officials for present-day America. There are nine minerals, they say, of which this.country would not pos- sess sufficient stores in case of sudden hostilities. ‘These are manganese, which forms an alloy with steel and hardens it; antimony, which hardens lead; chromium, another steel alloy; platinum, used in chemical processes; nickel, needed for armor plate and bullet jackets; quick- silver, used in explosives, thermometers, and for several other purposes; tungsten, needed in the manufacture of electric lamps and machine tools; tin, principally, used by the Army and Navy as a coating for cans; and nitrates, required in the making of artificial fertilizer. Note

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Pec OF a eae, Se tit” SN: ABP Aree et IR ee ete ee cele etn ARNG So gabe emer ‘70 Nobility. Not Degenerate, Genealogists Assert | 1385 two English barons, meeting AL casually during the invasion of Scot- land, discovered to their discomfiture that they bore the identical family colors. Each hotly disputed the other’s right to them, and a long drawn out battle fol- lowed before a court of chivalry. This fight, known in English history as the Scrope-Grosvenor suit, marked the beginning of the science of genealogy, which has been occupied with the tracing of lineages ever since. In this country, genealogy is a com- paratively new pursuit, but there is an organization, known as the American Genetic Association, whose members de- vote themselves to this interesting study, which has proved a great aid to historians. At a recent gathering of the Associa- tion in Washington, a prominent geneal- ogist declared that, contrary to popular impression, royalty and old families do not die out because of their age, or be- come degenerate and sterile on account of wealth and power. The fact that cer- tain distinguished names no longer appear in the British peerage, he said, is due to a preponderance of female descendants, aes He Made American Flag of 33,000 Wheat Kernels YLUING kernels of wheat upon a ¥ board for the equivalent of seventy working days, twenty-two-year-old Theo- phile Casaubon, of Los Angeles, produced this reproduction of the American flag. He used 33,000 kernels of selected hard wheat in the process. The flag is four feet long and two feet five inches wide and is set in a back- ground of natural colored wheat kernels. Each of the colored grains of wheat had to be dipped in oil paint three times to ob- tain the proper shade before it was glued in place. All of this painstaking work was done with just a single tool—a pair of small tweezers. Would Foil Bank Robbers A CAGE for bank tellers and cashiers, constructed with shutters which could be closed instantly by bank officials by a push button on the approach of a holdup man, was proposed recently to prevent bank robberies. The idea was advanced by an expert in such matters— a holdup man serving a life sentence in the Iowa State Penitentiary! POPULAR SCIENCE MONTHLY A Mechanical Substitute for Tailor’s Shears STEAD of snipping along a line with scissors, tailors can cut out clothes in a fraction of the time, it is claimed, by use of the new mechanical cloth cutter pictured above. The machine is housed in a small box, above which a guarded blade pro- truaes. The device is started by simply plugziny into a light socket and turning a switc The material, marked with chalk ‘to guide the cutting, is fed to the guarded blade, which cuts rapidly along the line at any angle or curve. The in- ventor believes the machine will prove valuable to tailors and small manufacturers by reducing the time necessary to cut garments. New Comet Discovered by an Amateur N AMATEUR astronomer liv- ing at Rosebank, a small com- munity near Cape Town, South Africa, distinguished himself re- cently by the discovery of a new comet. His “find” was confirmed immediately by officials of the Union Observatory in Cape Town. The comet could not be seen with the naked eye. It traveled slowly, and had no tail. The astronomers of the observatory plan to name it the Forbes comet, after its discoverer, and as encouragement to amateurs. Folding Pushcart Runs on Rubber-Tired Wheels EN tradesmen finish making de- liveries with a unique pushcart, re- cently exhibited at the Leipzig Technical Fair in Germany, they can fold it up and tuck it under their arms. When the bottom is lifted the cart folds together inthe manner shown in the photo- graph, and may be stored in a narrow space. An added ad- vantage of the new vehicle is that it allows delivery men returning with empty wagons to walk on sidewalks, out of the danger of traffic without taking up most of the room on the walk. The cart is said to be virtually noiseless, since it is equipped with rubber-tired, ball-bearing wheels. February, 199 Europe May Soon “Eat” jj, **Drinks”’ in Solid Form (=... now “wet” may soon go “dry” or partly so, but not as a me sult of international prohibition. The taking of “beverage” alcoho] in solid form—in other words, the “eating” of “drinks”—has been made possible through a new German invention, which was demonstrated at one of the principal laboratories in Berlin a few weeks ago, Alcohol in solid form is an old story to the chemist, but heretofore the chemicals used to turn it into a solid mass were jp. edible and often poisonous. But the new German material is reported to be nop. injurious and without taste or odor, Technically known as _potassium-alpha. diacetone-fructose-sulphate, it is nothj more or less than fruit sugar treated by a process, the secret of which is jealous|, guarded by its inventors. The principal commercial benefit to be derived from the invention will be the greater ease with which alcohol and al- coholic liquids—such as the |bases of many drugs and toilet preparations—cap now be stored and transported. Gives American ‘‘Talkies” Foreign Tongue HEN the “talking movies” first made their appearance, some lead- ers in motion picture affairs asked, “Won't this innovation seriously curtail the ex- port of American-made films to foreign, non-English-speaking countries?” Edwin Hopkins, a New York play- wright, has supplied the potential answer with an invention which he calls “vivi- graphic films,” which makes it possible to connect a voice record of an actor speaking in a foreign language with an American moving picture film. The ad- justment effected by the new device, its inventor claims, is so delicate that syn- chronization between the foreign sounds and the American lip-movements on the screen is almost perfect. Another benefit is that popular movie stars who look much better than they sound need not lose their jobs. In such cases, the “‘vivigraph” would supply the voices of actors or actresses who sound better than they look. When the peddler Mas disposed of his wares, he simply folds the new rubber-tired cart and lugs it home under his arm. ——— —-- © “he —h OD awe am at to one

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” fi rst e lead. “Won't she ex. oreign, play- unswer Vivi- ossible actor ith an 1e ad- ce, its L syn- ounds n the novie they such y the ound February, 1929 With endless tread fitted over rear wheels, the new motor- cycle can cross’ rough land. sv) 7 7 s ey A Three- Wheeled Motorcycle Runs on Endless Tread MOTORCYCLE in which two small, doughnutlike wheels replace the single large rear wheel has been designed in England for use in rough country and on unimproved roads. An endless tread is placed over the two rear wheels to fur- nish traction over especially difficult trails. The tread can be removed from the wheels and carried in the repair kit, after a difficult stretch has been crossed, just as a motorist can remove his tire chains when solid road is reached. Extra large balloon tires absorb much of the shock of the bumps. The machine is designed for the use of army and colonial officers stationed in undeveloped parts of the British Empire. Tiny Ocean Plants Build Houses of Health Glass N THE Antarctic regions now being explored by the Byrd expedition live billions of microscopic plants which build transparent houses for themselves of materials so rare and difficult to manu- facture that King Croesus himself would have been tvo poor to fashion even a small palace from them. The tiny plants, known to botanists as diatoms, construct miniature shells from silica and quartz which they extract from the sea water, in every square inch of which they live by the millions. When they die, their little ““houses” sink to the bottom, and so numerous are the little plants that this material covers the ocean floor for a half million square miles. The same substance has been smelted by electrical engineers in the making of lenses and of window panes which admit the sun’s ultra-violet rays. A small win- dow consisting of this transparent quartz is worth several hundred dollars. Paints First Scientific Portrait of Spectrum ITH the assistance of Dr. Irwin G. Priest and other scientists of the U. S. Bureau of Standards, Charles Bittin- ger, a noted artist of Boston, Mass., has painted what is considered the first scien- tifically accurate “portrait” of the spec- trum of the sun. In one of the laboratories of the Bu- reau, the scientists assisted Bittinger in selecting the colors that most accurately represented the spectrum. The spectrum POPULAR SCIENCE MONTHLY copied in the painting was obtained by passing sunlight through a grating con- sisting of thousands of fine lines scratched on a polished metal surface. A glass . prism is often used instead of a grat- ing to form a spectrum. Landmarks' Guide Pigeons Home? ONTRARY to accepted belief, bees, carrier pi- geons, and other “homing” animals have no innate sense of direction, accord- ing to Armand Rio, a French naturalist. They find their way back to their hives or lofts by familiar landmarks whichthey memorize by short excursions within eye- range of their starting point before they ~ set out on their flights, he says. The carrier pigeons which make the longest flights are the ones with the keen- est eyes, the best memories, and the greatest flying endurance. Ants find their way to their nests by remembrance of landmarks, he adds; and the same has been observed of barnacles under water, though these depend largely on touch. 71 Find Rare Handwork of Cave Men Jewelers IHE Neanderthal man, pictured by scientists as a flat-skulled, somewhat apelike individual who wooed his bride with a stone club, was a craftsman of no mean ability. Equipp:d with flint tools of the roughest and most primitive de- scription, he nevertheless turned out arti- cles for his daily use so delicately wrought as to challenge the skill of the most ac- complished modern artisan. Evidence of his proficiency was recent- ly found in the shape of two rare scraper knives fashioned from rock crystal that were unearthed by the American School of Prehistoric Research party which has completed excavating the rock shelter, Abris des Mervilles, located in the Dor- dogne region of France at Castel-Merle. These prehistoric implements, scien- tists say, are tens of thousands of years old. One of them is made of topaz of such beauty that it is a jewel as well asa weapon. The other, though not so fine in color, is of a workmanship which no living worker in quartz could rival. The discoveries were made by Profes- sor and Mrs. George Grant MacCurdy, of Yale University, and nine students. Novel Card Table Serves Also as Movie Sereen CARD party can be changed into a movie show merely by lifting the top of a new card table, switching out the lights and turning on the home projector. The table is designed to serve as a motion picture screen when it is not in use in its ordinary capacity. The top of the table is formed by two thicknesses, one on top of the other, and hinged at one side. The upper layer swings up, its under side forming the screen. It is held solidly in position by a Pushing the plug into a socket at one end com- pletes the electric circuit and fires the charge. stay while the pictures are being shown. The table can be folded easily and oc- cupies little room when stored away. Dry Cell Blasting Device Resembles Flashlight USES, for blasting, are supplanted by a new device which resembles an ordi- nary flashlight and furnishes electric cur- rent from three dry cells to discharge the explosive. According to the makers, it eliminates the danger of misfires and de- layed fires caused by fuse trouble. The firing unit of the device is a special plug to which are attached wires leading to the blasting cap. To fire the blast, it is necessary simply to insert this plug ina small socket in one end of the device and hold it there, exerting pressure against a spring inside, thus closing the electric circuit. Releasing the plug breaks the circuit. A ring at one end of the case makes it possible to hang the blasting unit at the belt.

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ee ae ion sp wt i Ss ie Sonne = tak ike. 72 POPULAR SCIENCE MONTHLY ] UMPS and jolts on rough roads rock the baby to sleep instead of disturb- ing him, when he is riding in a new auto- mobile crib, according to the inventor. The crib hangs, hammock fashion, in the rear of the car, supported by two hooks screwed into the crossbeams of the car top. The heavy duck cloth of which it is made is held in rigid shape by plywood bottom and a wire frame. The height of the crib above the floor is adjusted through chains by which it is hung from the hooks. A spring cushion in the bottom is made in three hinged sections, which can be adjusted to give the proper support whether the baby is sitting or lying down. The total weight of the apparatus is six pounds. It may be placed to one side in the rear of a closed car, as in the photo- graph, or it may be hung crosswise just behind the front seat. In an open car which has a metal top frame, it can be attached to the frame by means of straps. The crib can also be hung from a stand on lawn or porch as an ordinary sleeping crib, or attached to the ridge pole of a tent or a tree limb to pro- vide a comfortable sleeping place for baby when camping. One Time in Five It’s the Train That Is Hit T ONE out of five grade crossing accidents, the automobile crashes into the train instead of the train hit- ting the machine, announces the Amer- ican Railway Association, summariz- ing the annual toll of such accidents. In many cases the drivers first crashed through the crossing gate before hit- ting the train. During 1927, says the report, there was an increase of sixty- six grade crossing accidents over the twelve months preceding. Road Signs Teach Geology a peg placed along the highways near Ardmore, Oklahoma, call at- tention to interesting geological forma- tions along the road, giving the kind of rock and the age it represents. One signboard contains a diagram- matic cross section of the Arbuckle Swinging Auto Crib Rocks the Baby to Sleep Mountains, over which a main highway climbs. In constructing this road, many ledges were blasted away, revealing the rock formations. These serve as illustra- tions for which the signs form atext. Okla- homa is particularly interested in geology because its annual income of $500,000,- 000 from petroleum products is largely due to the efforts of workers in this par- ticular field of science. Closed Car Has Removable Top to Admit Sunshine CLOSED car with a top that can be folded back to admit, through glass windows, the beneficial rays from the sun, was one of the exhibits of a recent auto- mobile show in London, England. By moving a handle at the right of his seat, the driver can push back the canvas cover of the car like a curtain, exposing a roof of health glass. ‘Thus the occupants enjoy the equivalent of riding in the open, while still protected from wind and cold. The device also provides sight-seers with a view of mountain tops or city skyscrapers. The driver, by pulling a handy lever, rolls back the canvas top of the car, exposing a glass skylight. February, i999 Holland Tunnel Handles | 8,500,000 Cars in a Year | cigs and a half million automo. biles, carrying 42,000,000 passen, , passed through the Holland Tunnel, yp. der the Hudson between New York and Jersey City, during the first year of it, operation, officials report. Some of the elaborate tests made before the tunnel was built to insure againg carbon monoxide poisoning have been revealed by A. C. Fieldner, of the U. Bureau of Mines. When the tunnel was proposed, it was suggested that a steady stream of cars might give off more carbon monoxide than could be carried away, The Bureau of Mines constructed an ey. perimental tunnel, 400 feet long, in a mine near Pittsburgh, Pa. Small automobiles ran back and forth in it for hours while tests revealed the. best method of intro. ducing fresh air and removing contam- inated air. The most efficient method was found to be admitting the fresh air at the bottom and removing the poisoned air at the top. This system was applied to the Holland Tunnel. An automatic device that analyzes the carbon monoxide content of the air, and rings a bell and flashes a light if it becomes more than the safe limit of four parts in 10,000, was developed and installed in the tunnel. Besides, a series of fourteen in- struments, placed at the ducts leading away the contaminated air, automatically record the poison gas content. If the records show more than two and a half parts gas to 10,000-parts of air, the fans are immediately speeded up. “Auto Wheel Minus a Hub” Designed to Save Weight WIRE automobile wheel without the usual central shell that fits over the axle hub is one of the latest innovaticns in motordom. The wheel is said to weigh only eleven pounds. A similar wheel, with the usual hub, weighs eighteen. Seven small metal rings, or eyelets, securing the inner spokes, and one large one, holding the outer spokes, take the place of the ordinary wheel hub. The small eyelets fit over the studs of the brake drums, where they bolt in piace, tighten- ing the inner spokes. When these seven bolts are drawn up tightly, a large cap on the outside of the wheel presses against the fixed hub of the car’s axle. The wheel and the car axle hub are thus locked tight- ly together. In tests, the wheel is said to have shown remarkable strength.

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uary, 1979 idles Year automo. Ssen, nnel, un.. ‘ork and ar of its le before against ve been he U. § nel Was > Carbon 1 away, 1 an ex. 1a mine mobiles 'S while f intro. Oontam- method ‘esh air pisoned applied zes the ir, and comes arts in | in the en in- eading tically If the a half e fans ib”? _ the the icns eel, lets, urge the The ake en- ven cap eel ht- February, 1929 ‘rd’s-Eye View from Plane Pecrenls Buried City of the most paradoxical develop- ments of modern science is found in the fact that aviation is proving itself a yseful aid to archeology! There are many archeological “clues,” as ancient roads, ditches, and the like, which are invisible to the passer-by on the ground, but which can be dis- covered from a height in the air because the aviator’s bird’s-eye view of the ter- ritory gives him an opportunity to ob- serve conditions which form a scientifi- cally unmistakable pattern. A casein point was the recent discovery jn this manner of the site of a Roman town somewhere in England. Leading _ British archeologists believe that beneath ‘this site they will be able to unearth a - complete city of Caesar’s time, and they ‘hope that, when excavations’ actually begin,. they will find. streets, houses, temples, arenas, and other treasures. _ The scientists now preparing explora- tion plans which will bring this latest great archeological find to light decline to reveal the exact location of the mysteri- ‘ ous city of antiquity until their arrange- ‘ ments have been completed. Meanwhile, ‘msuspecting persons are walking daily -over this rich historic treasure-trove. Inflates Soft Tire with Air from the *“‘Spare”’ SPARE tire becomes a service sta- tion that travels along with you to supply free air for soft tires, through the use of a new “tire balancer,” devised by Tom LeNay, of Los Angeles, Calif. The device is extremely simple. It consists of a twelve-foot rubber hose with a cap at each end. These caps fit over the valves of two tires, opening them so the air can flow from the tire with higher pressure to the one with lower. In this way, also, the four tires of a car can be equalized in pressure to maintain the highest efficiency of four-wheel brakes, now standard equip- ment on all new cars. When the hose is connected with a soft tire and the hard spare tire, it allows air from the spare to pump up the flat tire so it can be driven to a service station for complete air service, or filled more easily with a hand pump, if a motor-driven pump is not available. POPULAR SCIENCE MONTHLY Oregon Village Sees Its First Automobile LTHOUGH more than twenty mil- lion pleasure automobiles were on the roads of the United States last year, the village of Agness, Ore., had never seen one until a roadster was sent there the other day. This community, on the Rogue River in the southwestern part of the state, contains only a handful of people and uses the river as its main highway. Grown children there had never seen a motor car of any sort. Then a dealer sent one of his cars up the river to give the village folk the thrill of their first auto ride. To ship the automobile, Every Little Dial Has a Meaning ITH a dashboard con- taining as many instru- ments as are earried by a trans-Atlantic airplane, a small run- about made its appearance at Southport, England, recently. The woman motorist who drives the car has the assistance—or hindrance!—of thirty dials, clocks, and buttons, not to mention a strange assort- ment of mirrors, and other “gadgets.” The owner claims to be the world’s champion buyer of auto accessories, and asserts that she can still pilot the car in spite of them! She likes to know how the wheels are going ’round. But the question is, can she look at the right dial at the right time? he removed the rear wheels and roped the machine in the bow of a twenty- six-foot motor boat. The swift current of the mountain stream made the passage - a risky undertaking, but it was completed without accident. Colored Telephone Poles to Liven Landscape ee ones up the landscape with colored telephone poles is a sug- gestion recently made before engineers attending a telephone association confer- ence in Chicago. One expert reported that his company had perfected a new wood preservative which triples the life of the poles and cen be made in a variety of colors. Telephone poles, he said, could be colored to harmonize with the landscape or to brighten barren spots. Doctor Makes 7,000-Mile Call by Radio DOCTOR, 7,000 miles from a pa- tient, diagnosed the case over the radio recently. A woman suffering from a dangerous malady in Buenos Aires, Ar- gentina, was put in communication with a specialist in Berlin, Germany, over a test short-wave apparatus. After a con- versation lasting twenty minutes, during which each could hear the other per- fectly, the doctor was able to diagnose the case and to cable the pre- scription. During the same week, a lock expert, in Idaho, was called on the tele- phone by an employee of an office in Oregon who had lost the combination to a large safe. The em- ployee placed the tele- phone receiver close to the door of the safe and the distant expert, listen- ing to the almost imper- ceptible sounds of falling tumblers in the safe door, directed her movements. In less than five minutes the door was open.

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FAO, eh ae me eh a ee eee . cS se e = = ‘ Sot Na ae ie etnias BB Pn ee hic ih tum ee eee 74 _ Tin Can Filling Station for Cigarette Lighters OM an empty tin can, you can make a filling station for vest pocket cigar- ette lighters by screwing on a newly de- vised combination metal tube, cap, and rubber bulb in place of the regular cap on the can. The can holds sufficient gasoline to fill many lighters and, the makers say, forms a handy and economical means of keeping a vest pocket lighter replenished. The bulb is designed to have a capacity just sufficient for the ordinary lighter. Thus one squeeze fills the tank to the top without making it overflow. Colds Blamed on Lack of Proteins in Diet EDERICK HOELZEL, of the Uni- versity of Chicago, announces a theory, backed up by experiment, that susceptibility to colds is largely a matter of diet. Persons who eat too much sugar and starch, as most people do, and vegetarians and others who live on a low- protein diet, are far more likely to “take - cold,” he says, than those whose food is high in protein content. This tallies with reports of Arctic explorers that colds are unknown among the Eskimos whose diet consists entirely of meat. The explanation of the Hoelzel theory is believed to lie in some undetermined relation between the amount of fluid in the body tissues and their sensitiveness. Starches and sugar tend to store up water in the tissues. When this intake of water is lowered the sensitiveness of the tissues is also lessened, so that a cool breeze or exposure to dampness does not so readily affect the system. This theory would account for the fact that fat persons, as ‘a rule, are more susceptible to colds than thin ones. Tin Foil Amazingly Thin r ror tin foil wrapped around chocolate, tobacco, or cigarettes is thick com- pared to the foil used in radio condensers, whieh measures 4,350 sheets to the inch! The thinnest foil provides 14,500 square inches from one pound of metal. Tin and lead foil are said to have been invented by the Chinese centuries ago, by hammering bars of metal. Today they are made by automatic machimery. POPULAR SCIENCE MONTHLY Did Man’s Legs Develop Before His Head? N EXHAUSTIVE study recently completed by Dr. Wilhelm Gieseler, of the University of Munich, Germany, tends to show that the pedal extremities of man’s remotest ancestor developed into human legs sooner than his skull evolved into a human head. The two most-disputed examples of human or near-human remains so far dis- covered—the bones of the Pithecanthro- pus or ape-man of Java and the Broken- Hill Man of South Africa—are so primi- tive, especially the skulls, that many anatomists deny them human rank But Dr. Gieseler is of the firm opinion that the Pithecanthropus was decidedly human. This conviction he bases upon the fact that his eye sockets are manlike rather than apelike, although he admits that the skull is low. And the thigh bones of both Pithe- canthropus and Broken-Hill Man, ac- cording to D. Gieseler, tell a still more eloquent story. These bones, he says, are entirely unlike those of apes, but closely resemble those of modern man. This leaves the question up in the air, for, while Dr. Gieseler contends that his findings show that man climbed the evolutionary ladder literally feet first, scientists of the opposite school declare that the disputed thigh bones may not belong to the “‘low brow” skulls at all. Tiny Dynamo Operates Ney Batteryless Flashlight A TWIST of the wrist supplies powe for a new flashlight. Turning th handle winds a spring that operates g tiny dynamo and produces current, fo a two-and-a-half-volt light. This Lilliputian electric light plant jg said to furnish light as long as the spring is kept wound. One complete windings said to supply light for two and a half minutes. While slightly larger than the ordinary flashlight, the invention weighs only two and three quarters pounds. Experiments with flashlights without batteries were made by the United States Army some time ago and re. ported in PopuLar Science Monts Stations Identified by. This Radio Dial HE latest radio dial is designed to flash the identification letters of each broadcasting station when its wave length is tuned in. Con- tact points are fitted in the dial at positions where the various stations are tuned in perfectly. Thereafter, each time one of the contacts is made a light flashes at the top of the dial and the letters of the station appear behind a lighted window. If wave lengths are changed, the contacts may be shifted. Ly. At the time, the Army was con sidering discarding batteries entirely. New Sugar Discovered in Dahlia Juice NEW sugar has been discovered in the juice of dahlia tubers by the U. S. Bureau of Standards, it was announced the other day. In experiments to find out the structure of inulin, a starchlike sub- stance found in dahlia juice, the sugar was discovered. Approximate- ly ninety-two percent of the juice was resolved into the already known sugar, called levulose or fructose, but the remaining eight percent was a mystery. In further tests, the strange substance was reduced to crystalline form. Construction of new radio dial. By means of con- tact points, the broadcasting station’s call letters are flashed in the window when station is tuned in. SES RSRSEREGSA oo Ff

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es New ight ies power rning> the perates g irrent for ; plant js ie spring rinding jg 1d a half than the n weighs nds. without United - and re. Monts. was Con- entirely. ered e scovered ibers by lards, it out. the ike sub- ce, the ximate- e juice known ructose, nt was ts, the ced to of con- letters ned in. February, 1929 Oceans on Frozen Pianet May Be Liquid Air sunward side of Mercury, nearest the sun of all planets in our solar gystem, may reach a temperature of nearly 800 degrees Fahrenheit, a heat ‘ent to melt lead, zinc, or tin and to all water on the planet’s surface permanently in gas form, like the air on according to Dr. William F. Meyer, of the University of California. — If Mercury were inhabited, liquid water to the population would be a rarity, ob- tainable only by means of complicated tus, as is liquid air on earth. On the other hand, says Dr. Meyer, the outermost planets of the solar system suffer from equally extreme cold. Uranus, next to the last on our system’s outer rim, bably experiences an average temper- ature of about 300 degrees F. below zero! This is close to the temperature of liquid air. If Uranus has an ocean, the scientist assumes that it must consist of that material. Volcanos on Uranus might ut icewater, melted from frozen rocks, as earthly lava consists of melted earth rocks. “Rheumatics”’ a Real Storm Warning LDERLY people who say E they can feel the approach of a storm or bad weather because their rheumatic pains increase, have been laughed at a good deal by the younger generation, but now physicians declare the old- sters are right. At a recent convention of the Central Society for Clinical Re- search, in Chicago, a trio of distinguished doctors announced that observations over anumber of years had shown that there exists, indeed, a close relation between storms, rain, and rheumatism. In ninety percent of the cases under observation, the patients were affected adversely by the approach of unfavorable weather. Holder for Pipe Cleaners bee smcker is provided with a new acce ssory in a holder for pipe cleaners which enables him to keep them within In this novel decorative holder, pipe cleaners ere kept always handy and in good condition. POPULAR SCIENCE MONTHLY arm’s reach on a table and pre- vents them from becoming dirty or bent out of shape. To lend at- tractiveness, designs are painted on the sides of the holders. Lizard Hypnotized! CURIOUS animal of the Southwest, the blue-bellied lizard, has been proved sus- ceptible to hypnotism. Edwin D. McKee, of the educational staff of the Grand Canyon National Park, has discovered that by keeping his eyes focused on those of the lizard as he ap- proaches the elusive animal, it will remain tense and still and can be pinned to the ground with a quick dart of the hand. Women Drivers Can Signal Now—No Excuse! ROTECTION for the dress sleeves and arms of women motorists, when they have to signal stops and turns on a rainy day, is afforded by a gauntlet of rubberized fabric just devised. The guantlet slips on the left arm, reaching above the elbow. It buckles snugly about the wrist to keep raindrops from running down the arm. When not in use, the fabric can be folded into a tight roll that occupies little space. If Brain Size Counted, the Whale Would Be Smart W substantiation of the theory that. intelligence does not depend on the apparent size or weight of the brain, but rather upon its convolutions, was offered recently by a German scientist who, after years of investigation, announced that the whale, never distinguished for its brain power, possesses the largest brain of any mammal. The record for brain-weight was estab- lished by a whale boasting some 247 ounces of gray matter! If brain volume had any influence on intelligence, it is apparent what an intellectual giant the whale would be when it is considered that the average brain of man seldom ex- veeds fifty ounces in weight! Novel Lamp Cord Holds Cigarette Lighter N ELECTRIC lamp cord sus- pending a heating element from which the smoker can light his cigar or cigarette is the latest novelty for the living room. The lighter comes in a variety of colors to match the twisted silk-covered wire cord and so has the appear- ance of a tassel at the end of the cord. Pressing a button turns on the electric current for the heating ele- ment. Another switch, located higher on the cord, governs the lighting of the lamp. The device is installed by simply un- screwing the electric light bulb, screwing in aspecial socket, and replacing the bulb. A New Kind of Mosquito! This Makes 141 NYONE who, in sultry summer nights, has had his patience tried by a twenty-five-minute hunt for a mosquito, will admire the persistence of C. H. Bath, sanitary inspector at the Panama Canal, who has captured a new species of this pestiferous family that had eluded experts during a chase lasting twenty-five years! The reason for the unending hunt of the sleep disturbers by United States health officials is the fact that some of them are breeders of malaria. The new capture, however, did not prove to belong to a variety of this kind. It was added to a series of 140 species which have already been listed. . World’s Greatest Gas Line CROSS rivers and through mountain canyons, from Amarillo, Texas, te Denver, Colorado, what is said to be the largest high-pressure gas line in the world was completed recently at the record rate of almost two miles a day. This 375-mile line, carrying natural gas from the Amarillo fields to consumers in Denvex and Pueblo, Colo., was in operation just 193 days after work was begun.

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Fig. 2. The edges are smoothed with needle files and larger half-round and crossing files. “JAWING is one of the most im- portant operations to master in decorative metal work. While the kT heavier and larger pieces, such as hinges and hardware, may be cut out more readily with chisels as explained last month, the smaller pieces and intri- cate pierced openings in large pieces are usually cut with a jeweler’s saw blade. When the sawing is neatly done, little finishing is needed; it is’ sufficient to round over the cut edges neatly with files and emery cloth before the final polishing. Those interested in model making or in radio construction will find a knowledge of sawing particularly useful. With proper saws an experienced worker can cut sheet metal up to \ in. in thickness, but the * beginner should start with thinner metal, say No. 18 gage. You must have a good saw frame, either of the jeweler’s or the coping saw type. If a coping saw frame is to be used, it should have two viselike clamps to hold jeweler’s saw blades, which have straight ends. Ordinary coping saw blades will not, of course, do for metal. Be sure to get the best saw blades you ean and do not worry if you break a number of them while learning to saw. Buy a dozen or two at the beginning; later on you can save money by buying them by the gross. You will also need a bench pin or saw- ing board (Fig. 1). Dimensioned draw- ings for two types of bench pins were given in a previous article of this series (December, 1927, issue, page 80). In its simplest form it is a piece of hard poplar, maple, beech, or birch, 4% by 4 by 8 in., screwed to the top of the bench so as to project over the edge 414 in. The wedge- shaped slot in the projecting end is 2 in. Decorati You Can Master the Use of Jeweler’s Saw Blades While Making an Attractive Brass Teapot Stand POPULAR SCIENCE MONTHLY February, 1929 ve Metal Sawing Fig. 1. The sawing is done on a wooden bench pin which has a triangular opening. deep and % in. wide at the open end. Attach it to the bench with flathead screws in countersunk holes. Before you start sawing, .be sure that the sheet metal is per- fectly flat and also bright and clean. Scrubbing it with powdered pumice stone and water usually will put it in good shape and give it a slightly rough- ened surface to receive the marks of the carbon paper used for transferring a design to it. Draw the design on stiff drawing paper, full size. Place a piece of new carbon paper face down on the metal, lay the drawing on this, and trace over the de- sign to transfer it to the metal. Large thumb tacks may be used to fasten the Fig. 4. Teapot stand made by Mr. Thatcher to illustrate the principles of sawing thin metal. By EDWARD THATCHER, Noted Teacher of Metal Work metal to a drawing board; then the carbon and drawing papers, which must be larger than the metal, can be secured over it with other tacks driven into the wood. The carbon lines left on the metal would become blurred in hap. dling, so go over them with g steel scribing point and scratch them in distinctly. Sometimes the surface of the metal is painted with Chinese white water color, which comes in tubes, to make a good surface for receiving the carbon paper marks. Some workers glue the Fig. 3. The edges of the teapot stand are turned over with a malleton a clean-cut block of wood held in the vise. design directly on the metal with shellac, but I have never liked this method. When a hammered surface is desired on the work, make the hammer marks on the metal before sawing. If you have done no sawing, try some experimental cuts in a piece of flat No. 18 gage copper. A No. 4 blade will be satis- factory for this. Generally speaking, the thinner the metal, the finer the teeth of the saw should be. Jeweler’s saw blades are numbered from Nos. 8/0 to 12, the last being very coarse. You will have to learn by experience the best blade to use for each job. Be sure that the blade is set in the frame with the teeth pointing down to- ward the handle. The blade should be held so taut that it will sound like a banjo string when picked. Hold the metal firmly down on the bench pin with the fingers of the left hand as in Fig. 1. Do not press the saw against the metai with much force; use only sufficient pressure to make the blade cut easily. Beginners are likely to press too hard with the result that the blade binds and breaks or runs off the line. Usually it is better to tilt the frame slightly forward and down toward the work except when sawing around sharp curves or turning a sharp angle. At such times the saw (Continued on page 126) ~»

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aTY, 1925 ade me the arp ich 26) Bebruary, 1929 POPULAR SCIENCE MONTHLY N THE present popular revival of in- terest in ping-pong, many of those who have fallen under the spell of its furious fun have asked themselves the question: “How can I build myself a good, firm, large table which will not be cumbersome or unsightly when folded up?” The latest answer to this question is the table illustrated in Fig. 1. It becomes, wher folded up, a four-leaf screen. It can be transformed from a table into a sereen and back again by one person. Although all the parts of the table are contained within the screen, there is noth- ing bulky or unsightly about it when it is set up in a corner of the room where only the face side of it can be seen. Either the dark green playing surface can be left ex- posed as the face of the screen, or a decorative covering of figured chintz or other fabric can be fastened with tape or thumb tacks to the four standing leaves. It is true, of course, that a large Fig. 1. This sub- stantial ping-pong table can be trans- formed, legs and all, into a screen. self-contained as illustrated. Then they can be folded into the back or underside of the table top as shown in Fig. 2. The long rails, which come apart in the middle, are placed in the back recesses of the middle sections. All are held in place by springs. The playing board may be made of %4- in. plywood, which is often used in making commercial tables, but this gives an un- wieldy top unless a permanent table is desired. Instead, the top of our table is made of 4- or 5¢-in. plywood reinforced by % by 2 in. strips around the edges and across the middle. The use of pressed wood will still further decrease both weight and expense. It is a light, strong, 77 ing-P ong Table ‘c Holdsinto Screen Although of Tournament Size, Jt Can Be Stored in Small Space By CHARLES A. KING stiff artificial board of warm brown color; its .close grained, smooth surfaced texture make it pecul- iarly suitable for this purpose. However, almost any of the vari- ous pulp fiber boards on the mar- ket will be satisfactory and will cost and weigh less than plywood. In making the board, first cut the four sections 27 by 60 in. See that each corner is perfectly square. If the pieces are cut from the nearest stock size, 32 in. by 6 ft., there will be considerable waste, which may be reduced if pieces 32 in. by 10 ft..can be obtained. If the latter are cut exactly in the center with a thin, fine saw, the only waste will be a 5-in. strip from the edge of each. From seven pieces % by 2 in. by 10 ft. of whitewood or other semihardwood, miter the reinforcements around the un- derside of each section. Plane their inside edges carefully, glue each piece as shown in Fig. 3, turn the board over, and drive 1-in. No. 15 brads slantingly through the top, setting them just below the surface. Before fastening (Continued on page 111) dining room table may be turned into a ping-pong board, but it is usually too small for a real game. The standard size for a home ping- pong table is 4 by 8 ft.; the tour- nament table is always 5 by 9 ft. and allows a much better game to be played. If a dining room table or other large, substantial table is avail- able, the problem of making a ping-pong table is obviously much simplified. It is necessary to make only the folding top, which can be stood up out of the way to serve as a screen when not in use. In addition, two pieces of % in. thick board 9 ft. long will be needed to place on the table—or, if neces- sary, on two small tables—for supporting the folding game board. If you wish to complete the table, you can, of course, provide detachable legs very easily and stand them away in a cupboard when the table is not in use. It is better, however, to go to the extra work required to make the legs ee UNDERSIDE/ VIEW _ HOOKS FOLDED MITER JOINTS DOWELS 9-0" pitt pa | aaa : | : NET ; 00D © st //F LENGTHWISE Postal| te WALL BOARD : Se sips Kx ot able eG ae | [ LSrries 4x2 iis = SEEN) “PN ninces’ SIDE RAIL —~ Peet (REMOVABLE) [at ae oe WIRE HOOKS ony fhe LEGS 17" LONG : | oe al ®, SIDE VIEW ‘ oe | Sel T CoRRUGATED peat —- 27 ~{FASTENERSAT = ALL MITERS . Fig. 2. Side and end views of the table; the underside of the top with the legs folded and the side rails stored away; and a drawing to show the rear of the screen, although ordinarily this side of it will be hidden,

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~ POPULAR SCIENCE MONTHLY February, 199 ontrolling a Model Railway A Simple Way to Install a Central Switchboard from Which to Govern All Train Movements—Changing Voltage on Grades By FreEpDERIcK D. Ryper, Jr. UST as it is necessary to plan the track layout of a model electric railway be- fore you start building, so it is wise to make a preliminary study of the type of electrical control system you wish to install The ideal control system would be one that would permit you to sit in front of the control panel and perform all the opera- tions of running the trains with- out leaving that position. And that de- gree of control can be obtained easily with the equipment now available. Automatic reversing electric locomo- tives, of course, are needed, as well as electrically -operated switches. Your problem is, therefore, one of arranging the control panel so as to make it con- Fig. 1. Apron-type control panel used by James A. Baker, of Darien, Conn., for operating his exceptionally well-arranged model railway. For track layouts placed on the floor, a simple design for a control panel is shown in Fig. 3. Cheap yellow pine siding is used to make it, with a piece of plywood for the surface where the switches and control buttens are mounted. As shown in Fig. 2 the top is hinged at the bottom edge to facilitate wiring. The fourth row consists of small toggle switches such as are sold to radio set builders. Push. pull switches would do just as well as the toggle type. Each of these switches controls the cur. rent flow to a different part of the main line so that the current can be cut off from different sec. tions of the main line and one train stopped at these points without stopping any other trains that may happen to be running on other parts of the track. This method of sectional control was de. scribed in detail in articles in the Decem- ber, 1925, issue of PopuLar Scrence MonTHLy, page 72, and the January, 1926, issue, page 80. ~ The two knobs are rheostats of the heavy-duty type. They should be capa- ble of carrying at least 2% am. venient to handle and to install the wiring. The location, size, and construc- tion of the panel is governed by the size of the system and the position in whieh the control panel must be loeated. If the track layout is placed on a shelf or bench, the panel can be installed most simply by fastening it edgewise tothe bench like an apron. A piece of plywood can be used. The control panel of the elabo- rate and unusually complete model railway shown in Fig. 1 is a good example of this type of construction. TO ZERO TAP ON VOLTAGE TRANSFORMER TAP TAP re = TO LOW TO HIGH TO TRANSFORMER VOLTAGE (OR TO SINGLE CONTACT OF SWITCH IN F/6.4) FIG. 4 FIG. 5 wo Won peres of current. One controls the ONE GRADE OTHER GRADE current to all sections of the termi- nal, and the other controls the cur. rent to all parts of the main line ex- cept the grades. This makes it possible to control a jocomotive engaged in switching operations in the terminal without affecting trains running on the main line. A double-pole double-throw knife switch between the rheostat knobs controls the current to the grades, Whatever goes up eventually must come down again, so if you have an up-grade in your track layout there must also be a down-grade to get Fig. 4 (at left above). Fig. 5 (at right). Fig. 2. Desk type of control panel as seen from rear, with panel raised to show connections. A study of the electrical control as worked out on this particular unit will give you an idea of how to arrange a panel that will be suitable for your own system. The top and second row of buttons are used to control the electrically operated switches in an interlocking arrangement that will be explained farther along in this article. The buttons in the third row are connected to the sidings in the terminals. Push-button control of the sidings is de- sirable because it forces you to keep your finger on the button while a train is being operated on a siding and prevents acci- dents caused when a train rushes into a siding, crashing into a bumper or, perhaps, wrecking part of the station. These are standard half-inch doorbell push buttons obtainable in any electrical supply store. Quick acting voltage switch. Switch for controlling power on grades. back to the original level. Con- siderably more voltage is needed to drive the locomotives up the grade than is required on the level, and on the down-grade the voltage must be reduced to prevent the (Continued on page 120) Fig. 3. Front of the panel shown in Fig. 2. It gives complete control of all train operations. becor dema

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Y, 199 is of S are » st as ch of cur- rt of rrent oints ther This em- INCE ' eX- 3 it tive ons Ling nife obs Jes, ust an ere On- h Hf My) in ‘| ly YY Hf pay bh 0 tia OW that motorized home work- shop machines and small wood turning lathes are in use in so many homes and wood turning is becoming so popular a hobby, there is a demand for designs and projects that are a step in advance of candlesticks and a elementary articles with which be- ginners are at first content. Readers have indicated that they are eager to try something requiring more skill. A fascinating project is therefore suggested—the turning of a solid ring of wood. This requires no additional tools or equipment. It represents an advance in the line of faceplate work discussed in the October and November, 1928, issues of Poputar Science MonrHacy. An example of ring turning is the nap- kin holder illustrated in Figs. 1 and 2 ut hs x ne! i Ci craftsman in turning rings. POPULAR SCIENCE MONTHLY _——. Rings of Wood How to Make Napkin, Tie, and Towel Wf A fascinating field for experi- ment is offered tne amateur This is turned partly between centers and partly on the face- plate. If it i is desired to Ra two napkin rings, cut a piece of wood at least 4 in. thicker and wider than the finished outside diam- eter of the ring and about 2 in. longer than the combined length of two rings. For two rings of the dimensions indicated in Fig. 1, the rough stock should be 2144 by 2% by 6 in. Square one end of the piece carefully with the sides, an operation which may be done conveniently by sawing the stock in a miter box. Locate the center by drawing diagonals and bore a 3¢-in. hole about 14 in. deep with a gimlet or twist bit. Fasten the piece to a screw chuck, which is simply a small faceplate with a single heavy screw in the center. If a screw chuck is not a part of the lathe equipment, an ordinary faceplate may be used. Screw a piece of wood to “ ~ > Tis - —— Holders, and Round Picture Frames Yyy //; By Herman Horta the faceplate and turn a circular disk as explained in the October, 1928, issue, page 112. Mark the center on the disk while it is revolving in the lathe and bore a 3¢-in. hole, countersinking it on the side which is against the faceplate. Insert a heavy flat-head screw of the proper length (depending upon the thickness of the disk) and fasten the piece to be turned firmly to the disk as in Fig. 3. The dead center is now run against the free end of the 244-by-24-by-6-in. piece, which is rounded off and smoothed in the usual manner. The napkin rings are then laid out, turned, and sanded as explained in previous articles, ~ When the outside shape of the rings has been formed, the dead center is moved out of the way and the tool rest placed close to the end of the piece and at right angles to the lathe bed. Mark the diam- eter of the 1-in. hole with a pair of dividers (use the second method de- scribed on page 132 of the Oct., 1928, issue) and start the boring of the hole with a very sharp round-nose chisel. Be- gin in the center and gradually work out towards the (Continued on page 116) Any wood turner who masters these four simple projects will be able to do a large variety of similar work A close-grained wood such as birch, maple, mahogany, or walnut should be used, or, for more orna- mental effects, a combination of contrasting woods glued in layers,

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Luxuries t ” ELEN, I saw a wonderful house teday.”” I lit my pipe, hitched up a chair to a com- fortable place near the fire, and started on a “selling talk” I had prepared for my wife. “Went out to look at that ‘model house’ in Meadowville today. Talk about your 1929 styles! I didn’t realize how out-of-date our place is getting until I saw the new one. It’s the last word— even to shoe-shining cabinets that fold in the wall and colored tile bathrooms!” “TI suppose you ‘want to go right out and buy it,”’ observed Helen. “Td like to,” I admitted. “So would I. But you know mighty well we can’t afford it. What’s the matter with making our own place over, a little at a time? Let's make our own synthetic 1929 home.” That was‘the start of the argu- ment. The finish was that the next Saturday we made a tour of the manufacturers’ show windows to see what ways there were to bring our old-fashioned dwelling up-to- date. That tour was a revelation. Al- though it was bewildering to see in a single day all the new labor-saving devices and finishes that can be put in one’s home, certain dominant ideas stood out. YR instance, we were surprised how many ugly things are tucked completely out of sight in the 1929 home. You may enter a living room and look in vain for radiators—yet the room is comfortably heated. New steam radiators, extremely nar- row, will hide within the wall under POPULAR SCIENCE MONTHLY By MILTON G. STURGISS “ ventilating”’ pane of bulging glass, with shutters beneath. For casement windows—a -” OW can I make my house more comfortable and more conven- ient?”? The author answers this question, asked by thousands of American home owners, with the story of a trip which he and his wife made to the showrooms of manufacturers. You probably will be as amazed as he was at the variety of luxuries that are avail- able. True, many of the conveniences he tells about in this article are more costly than so-called standard equip- ment, but you must determine, as he did, which of them are worth enough to you to justify the extra cost. After all, the value of a piece of equipment must lie in its use to the individual householder.—The Editor. o Add to the Home Magical New Comforts and Labor-Saving Inventions to Help Bring the Old-Fashioned Dwelling Up-to-Date February, iy in 1929, we learned. A white ena panel in a tiled bathroom wall folded out when I pulled a small handle, and »,. vealed itself as a shoe-shining cabinet, A surprising built-in cupboard only ay inch or two thick, on a kitchen wall, revealed a folding utility table and ay ironing board when Helen opened the door. WE WERE delighted with many other built-in ‘improvements. 4 recess in the wall, lined with asbestos. coated steel, offers a handy receptacle for the electric iron when not in use. A ventilated aluminum door allows the iron to cool quickly and safely. One ingenious invention is a cabinet set into the kitchen door, used for re. ceiving delivered packages when you are not at home. The grocery boy inserts his bundles through an outer door; returning home, you unlatch the inner one and remove the pack- ages, which, meanwhile, have been protected from rain and_ stray animals. One of Helen’s pet dislikes is te clean out the ashes in an open fire- place. That messy job takes a lot af the fun out of a log fire. But on ow tour we ran across a self-cleaning hearth. To empty ashes you need only grasp an inconspicuous lever, unlock it with half a turn, and pull. A trapdoor beneath the hearth swings open. Down a chute go the ashes, Meanwhile, through a clever ar- rangement of levers and cams, 8 © curved plate covers the opening 90 that dust cannot fly up. ’ To us, the modern home was & museum of built-in conveniences. What else? a window. They are only three and a half inches thick; yet, because of their many-finned design, they radiate as much heat as others twice the size. Warm air emerges through an incon- spicuous grill. The telephone and its monstrous di- rectories had cluttered our living room for years. No wonder we were impressed to find, in one showroom, a handsome little telephone nook built into the wall. A telephone occupies its center shelf. Below is a recess for directories; above, ~ carved door hides the unbeautiful bell x. A glance at a model kitchen showed the absence of the old unsightly garbage pail. Instead, there is a trapdoor in the wall. Scraps thrown into it disappear down. a chute, to be destroyed in an in- cinerator in the basement. Bulky objects have a way of vanishing A space-saving radiator, only three and a half inches thick, hides within the wall beneath a window ledge. Its many-finned design is claimed to afford abundant radiating surface. A pageant of color! Spectral-hued pots and pans are only a start. We wouldn’t believe, until we saw with our own eyes, that we could buy a heating boiler in sky blue or scarlet. In the bath- room, where staid white has so long held sway, many-hued tiles, alternating some- times with striking-black, are now newly popular. S VARIED as their colors are the LA materials in which these tiles are offered. One of the novelties is a s0- called Belgian tile that is flexible, and can be bent around corners. It is coated upon zinc, and may be applied to any smooth plastered wall. A modern luxury for the bath that excited our envy was a glassed-in shower compariment trimmed in gleaming chro- mium plate—built up from the bathtub’s: rim nearly to the ceiling. Splash away to-

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t of our eed ver, —sa8.732 8 SwTt i & February, 1929 our heart’s content, and not a drop can tter on the floor. A grille at the top of ass door provides ventilation. Built into the wall, a new bathroom heater contains three objects that look like electric light bulbs. ‘To my surprise, when I pressed a switch, a pervading warm glow issued. ‘The bulbs are espe- cially designed for heating, although they contain filaments like ordinary lamps. ‘A VING examined the new “fixtures” of the modern house, we turned next to interior wall finishes. Once you could take it for granted that-living room walls would be covered with wall paper. Now they are paneled, in fascinating new materials. Or, if you fer, they are covered with a textured, stuccolike finish applied with a brush and molded and colored to suit any style of architecture. ; For wood paneling, among the novel- ties, there is a new fireproof wood, chem- jeally treated. It looks like ordinary wood, and retains its finish as well, yet its makers claim that it cannot burn. It is used for wainscoting, trim, flooring, doors, or molding. Another paneling is a “‘ woodless wood,” made of Portland cement and asbestos. Only when you rap the panels, or beams of the same material, does a stonelike response betray the substitution. A third is a grainless wood, made by shredding actual wood and then pressing it together again. Dense and tough, it is said to be proof against cracking and impervious to moisture. Now, too, there is an amazing wall finish that transforms painted plaster walls and beams into wood. Even the grain of wood is imitated. The product is a thick liquid. A companion finish produces an effect of stone. At the beauty of stone walls in Colonial, Spanish, or even modern- istic style is possible through new “plastic paints,” giving a variety of textured finishes. ‘These are powders, which are mixed with cold water and applied with a brush to the wall or ceiling after any wall paper has been removed. Then they are molded to the desired texture by manipulating the surface with a brush, whisk broom, comb, sponge, wad of POPULAR SCIENCE MONTHLY $1 paper, or even the palm of your hand! They harden to a stone- like finish. Water or oil colors are used to tint them; should you tire of a water color after a few months, it can be re- moved with hot water and soap, and a new one applied. A glazed finish is a possible variation. For those who still prefer the old styles, another novelty is “‘wall paper” of cloth! It is hung like wall paper; and if soiled, after months of wear, it may be wiped clean with a damp cloth. Casement windows have lately come into vogue for Pull this inconspicuous lever, and a trapdoor in the hearth dumps the ashes down a chute to the cellar. modern interiors. But there is a tempta- tion to keep them shut when a gale is raging outside, even if the air in the room is becoming unbearably stuffy. Now it is possible to admit the air, but keep out the blustering gale, by inserting one or two new “ventilating panes” of bulging glass instead of the standard flat ones. Openings in them let in more or less air, as desired, through control shutters. The hooded shape keeps rain out. New windows, some in handsome steel sashes, swing inward for easy cleaning. An innovation in window screens is one that is wound on a roller like a shade. A corner of the 1929 kitchen. The photograph shows, left to right: Utility table that folds into wall; incinerator chute; electric sink with built-in dishwasher; wall thermometer; handy cabinet. A glass-inclosed shower bath cabinet is the latest luxury in the up-to-date home. Note the modern bathroom—fioor and walls tiled. Helen and I soon discovered that we might make over even the ex- terior of our house in accordance with modern ideas. We were im- pressed by the new beauty of standard building materials. New stuccos, among them a waterproof, elastic material that will bend with- out cracking, have attractive textures and tints; and face bricks now offer a many-hued, colorful wall of purple and rose, red and chocolate brown hues. HERE are almost as many different types of roofs as houses to put them on. Asbestos shingles, durable and fire- proof, are offered for roofs and siding. They are applied directly over the old surface and provide a pleasing variety of color possibilities. Copper shingles are obtainable in strips that are light in weight and give a roof of exceptional permanence. An attractive French tile for roofing is made of concrete. An in- teresting novelty, where economy is para- mount, is a “print roofing” made of asphalt-saturated rag felt, that comes in rolls. Applied directly on a new roof, or over old shingles, its fabric carries a shingle pattern. A house that is warm in winter and ‘ cool in summer is possible through the use of one of many heat-insulating ma- terials. One is a composition board manu- factured frora cane fiber, used under the plaster for inside walls and ceilings. It supplies insulation back of brick, wood, or stucco exteriors. In homes already built, it sheathes the walls of attic and basement. Plastic paint for wall in- teriors may be applied directly over it; or decorative panels may be created with gold bronze and stenciled Japan colors, applied with the aid of glue size and varnish. Among other coal-savers are cork boards, quilts of felt or other substances used as lining in (Continued on page 160)

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POPULAR SCIENCE MONTHLY MONTHLY ARCHIMEDES Fate of Applied Science SumNER Biossom, Editor Raymonp J. Brown, Managing Editor WaxkeE.inec, Home Workshop Editor AurFrep P. Lang, Téchnical Editor Epcar 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 and Its [os and in Canada, $2.50 the Year. In All Other Countries, $3.00 the Year. Railroads, Airplanes, and Speed ECENTLY published reports of the latest and largest locomotive in the world, built for the Northern Pacific Railroad, stress the fact that engine and tender are half the length of a city block, weigh a million pounds, can pull a loaded train two miles long on a level track, and consume twenty tons of coal and 14,400 gallons of water an hour. But nothing is said of its speed. Indirectly that omission explains one reason why this country is being criss-crossed with air lines. Speed, especially in trans- portation and communication, is the great discovery of the age, and for more than two decades our railroads have made no progress toward greater speed. Twenty-five years ago a man could board the Twentieth Century Limited in Chicago and be in New York just as quickly as he can today. In fact, the time now is two hours longer than it was when the run was made in eighteen hours. Other famous trains still run on time schedules established years ago. And it isn’t because a railroad train can’t go faster. The Empire State Express, running between New York and Buffalo on the fastest schedule in this country averages only 48.7 miles an hour. Yet that same train covered a mile in 1893 at the rate of 113 miles an hour. So long as our railroads are content to live in the past, resting on honors already won, the swift winged airplane will continue to prosper because it answers the modern demand for speed— and more speed. Nothing can stand still and survive. John Early, Leper RITE down, among the decisive episodes of history, the strange story of John Early, leper. It is a story not only of a brilliant victory of medicine over the dreaded scourge of centuries, but of a dramatic battle to save a man from himself. John Early, a North Carolina mountaineer, became no- torious for his many escapes from leper colonies and for his armed resistance to confinement and medical treatment. One day about five years ago, the national capital was startled to learn that he had escaped from the National Leper Home at Carville, La., and had registered in a Washington hotel. Pursued, he armed himself with a rifle, hid in his mountain home, and for months resisted capture. But at last, in May, 1927, he gave himself up to Federal officers and was taken back to the leper home. There he submitted to treatment. Now comes the announcement from the United States Public Health Service that John Early has recovered. His February, 199 terrible disease has been arrested by a new method of treg by injections of chaulmoogra oil. He is scarred, but free! Thanks to heroes and martyrs of medical research, the tray) cry, ““Unclean!”’ is passing from the earth. Its passing renews hope that remaining scourges, such as cancer, soon may be overcome. The Double Duty of Science ENJAMIN FRANKLIN once observed that while his attention was concentrated on attempting to eradicate one of his bad habits, another would creep in unaware. Every now and then the same thing happens to the human race as a whole. While people’s thoughts are occupied with the problem of crossing the ocean by air, the tragedy of the Vestris brings yg to a shocked realization that much still has to be done before we can honestly say that crossing the oceans—even by ships—g absolutely safe. And while the sinking of the Vestris may or may not haye been preventable, the fact remains that such a catastrophe ig g blow in the face to our vaunted scientific progress. As pointed out on page 30 of this issue, the business of science is to render safer our present modes of travel, as well as to perfect new ones! _ War on the «Common Cold” AN’S most mysterious and most expensive ailment is what is foolishly called a “common cold.” ‘Two good hard common colds are the average annual lot of everyone jg America. And a recent survey showed that colds are respon. sible for forty-seven. percent of the time lost in industry. Science has not yet located definitely either the cause or its cure. But like every disease about which medical knowledge is scarce, theories are plentiful. The demonstrated facts seem to be that colds are caused by germs; that these germs are most virulent in the early stages, and that colds are most prevalent at certain seasons of the year. Nothing more. However, studies just begun at Johns Hopkins Universi may result in determining reasons and remedies for the cold an achievement from which everyone of us would benefit, This would save hundreds of millions a year in wages and— more important, would reduce the number of deaths from pneumonia, diphtheria and other destructive diseases. Nature built the body machine. Science teaches us how to keep it well oiled—to keep it free from disease. Marvels We Take for Granted ORE than 20,000 electric signs flash on at dusk in New York City. The bulbs in these signs number more than a million. Still, nobody wonders whether they will function when the switch is thrown. Their reliability is taken for granted. Yet, it was only in 1888 that the first electric sign in the city caused a seven-day sensation. And eight years earlier, passengers on an Atlantic steamship sent the company a note of congratulation on the working of electric lights on board! It is the uncertain that commands our attention. The biggest thing on earth is the ocean tide. The greatest power- plant in our heavens is the sun. They function like clockwork. Weare sure of them. And we give them little thought. Similar- ly with inventions, and the products of man’s ingenuity. We marvel awhile then turn to the next wonder. When their reliability becomes assured, we take them for granted. They Are Saying— . ATER power in the future will be inadequate to meet the demands for electrical power.”—Thomas A. Edison. “TI felt infinitely more concerned for my safety in crossing Fifth Avenue, New York, than I ever felt in the Jungle.””—Ar- thur Vernay, big game hunter. “Our American women are in better physical condition than our men. Women do not wear too many clothes.”—Dr. Eph- raim R. Mulford, President of the Medical Society of New Jersey. ‘Coal, which costs less than $3 a ton at the mine, should be turned into gas at the mine, furnishing the producer with $15 worth of by-products per ton.” —Dr. Arthur D. Little, famous chemist.

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7, 1999 tragic enews ay be what e in r its ge is New tion n in lier, ote ver- ork, lar- 1e1r be PS 5 »h- ew 15 us

POPULAR SCIENCE MONTHLY 83 i: ~~ 3 < ~~ % , &

Look for this mark on every Radiotron E. F. McDONALD, Jr. President, ZENITH RADIO CORPORATION, says:

“*We determine the performance of all of our receiving sets by using RCA Radiotrons. That is because they materially enhance the reception of our instruments. We urge our dealers to recommend them for initial equip- ment and for replacement.” : CIM na Z. If you wish your receiving set to give you the best results, renew all of your vacuum tubes with RCA Radiotrons once a year at least. It is better not to use new tubes with old ones. RCA RADIOTROA RADIO CORPORATION OF AMERICA , New York , Chicago + Atlanta + Dallas + San Francisco

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What Feeds Gas to Your Car? POPULAR SCIENCE MONTHLY A Haughty Woman Driver Learns from Gus Why It Pays to Know How Fuel Supply Systems Work By MARTIN BUNN - OU the mechanic here, my ‘man?” A harsh, feminine voice rat- tled Gus Wilson’s eardrums and brought his head around with a jerk. “Yes’m,” he mildly replied to the bossy female whose car had coasted up behind the veteran auto mechanic. ““ Well,” she snapped, “I hope you’re not as dumb as most auto mechanics. I know something about cars myself and I don’t intend to be swindled. Can you fix this car or can’t you?” ““What seems to be the matter?” Gus inquired, still mildly. “*It’s your job to find that out,” she replied pointedly. Joe Clark, Gus Wilson’s partner in the Model Garage, had strolled over to watch and the older man slyly winked at him as, without further remarks, he raised the hood of the car. ““Now don’t try to tell me it’s the vacuum tank,” she warned Gus. “I took off the pipe and primed it with gasoline several times and that isn’t the trouble.” “Primed the vacuum tank?” questioned Gus, puzzled. “That’s what I said,” she snapped. “T took off that pipe right there.” And she pointed to a round metal tank fastened to the side of the engine. “T don’t wonder that didn’t do much good,” Gus observed with a grin. “‘That tank, lady, is the oil filter. This car hasn’t got any vacuum tank!” “What!” she gasped, and her domi- neering attitude went down like a flat tire. “No vacuum tank? Why, the course I studied said that all cars had vacuum tanks.” ““Not quite all,” grinned Gus. “In Ford cars, both the old lizzies and the new ones, they stick the supply tank up high enough so the {gas’ll run downhill into the carburetor. It’s called the gravity system. But there’s at least three other ways of doing the job. Air pressure is one of °em. Then there’s a dinky little magnetic pump that draws juice from the battery to work it. And this boat and several other breeds use a new kind of a mechanical pump.” te HY so many different systems?” the woman inquired interestedly. “TI should think only one could be the best, so why use the others?” “Differences of opinion is what makes horse trades, ma’am,”’ Gus replied. “Each system has its good points and its bad. It looked for a while as though the vacuum tank would win out. Nearly all cars had ’em. But better roads and faster driving brought out a bad feature. When you're sailing up a long, steep mountain road, or burning up the road on the level, the vacuum tank falls down on the job. It depends on the vacuum in the manifold to work, and when the throttle is nearly wide open there isn’t any vacuum. “The pressure system gets around that trouble, but it costs more to instal!, and there’s always.a chance for a leak in the pressure lines. The gravity system, though, can’t go wrong unless somebody repeals the law of gravity!’ “Tf it’s so perfect, why doesn’t every car have it?” the woman inquired. OME designers,” explained Gus, “don’t like the idea of putting the gas tank in the cowl back of the dash, and that’s about the only place in a modern car where it will be high enough to feed right on the hills. It works out all right in light cars with small gasoline tanks, but a big car needs a bigger tank that takes lots of room, and when it’s full there’s a lot of weight up in the air instead of down near the road where it ought to be.” “What's the matter with the other two systems you mentioned?” she asked. “Well,” Gus replied, “‘the electric pump goes dead if something happens to the electric wiring, and the new mechan- ical pumps haven’t been on the market “frimed the vacuum tank?” Gus grinned. “That, lady; is the cil filter. This car has no vacuum tank,” long enough to be sure about what they do after years of service.’ “Which system would you rather have on your own car?” the woman inquired. “Any one of ’em,” said Gus, “so long as it was installed right and put where it could be repaired easily.” UT you'd want to be able to recog- nize it, wouldn’t you?” she smiled. “That is kind of necessary,”’ admitted: Gus. “And there’s another thing about automobiles you ought to know. Don't jump at conclusions. You made up your mind that something was wrong with the gasoline feed and you were bound you'd find that kind of trouble.” “What is wrong, anyhow?” “Oh, I fixed that while we were talk- ing,” Gus grinned. “The high tension wire had snapped off at the coil. Now I'll drain the crank case to get rid of the gasoline you poured into the oil filter, and put in fresh oil.” She cordially thanked Gus and drove off. Joe then spoke up. “Good work, Gus. Know who that was? That’s Hank Preeble’s widow. He left her a big trucking business over in Tupperville. She’s got a lot of repair work she could throw our way. It sure pays to treat *em right.” “Sometimes it’s a tough job, though,” grunted Gus, “I certainly wanted to tell that dame to go jump in the lake!” IF ter 20 pay Ev sar

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TY, 199 That, ank,” they on’t your vith und alk- sion Yow the ter, ove hat air ure h,” tell February, 1929 Medium Size Eveready Layerbile “B’” Battery No. 485. 3% thick, 45 volts. POPULAR SCIENCE MONTHLY inches The original Eveready Layerbilt “B’’ Battery No. 486. 4 7/16 inches thick, 45 volts, EVEREADY LAYERBILTS GIVE 252 TO 3024 LONGER SERVICE, YET COST YOU ONLY A FEW CENTS MORE IF YOU have been buying the Medium Size Eveready “B” Bat- tery No. 772, at $2.75, add only 20 cents to what you have been paying, and get the Medium Size Eveready Layerbilt “B” Battery No. 485. For these few extra cents you get a genuine Eveready Layerbilt, made of flat cells. It will last 25% longer than the cylindrical cell battery of the same size. If you have been using the cylindrical cell Heavy Duty Ever- eady “B” Battery No. 770, at $4, next time add just 25 cents to its price, and get the Eveready Layerbilt “B” Battery No. 486. This is the famous original Eveready Layerbilt, the longest lasting, most economical and convenient of all Evereadys. It contains much more active ma- terials than the cylindrical cell Eveready of the same size, and lasts 30% longer. It is possible to pack more active materials inside an Ever- eady Layerbilt because it is built of flat cells. These pack together tightly, occupying all available space inside the battery case, and eliminating many soldered con- nections. The waste spaces be- tween the cells of a cylindrical cell type of “‘B”’ battery are avoided. An Eveready Layerbilt is all battery. That is why it lasts so much longer. Next time you buy “B” batteries, get Eveready Layerbilts. Layerbilt construction is a pat- ented Eveready feature. Only Eveready makes Layerbilt bat- teries. NATIONAL CARBON COMPANY, Inc. New York UCC) San Francisco Unit of Union Carbide and Carbon Corporation TUESDAY NIGHT Is EverEADY Hour Nicst —East of the Rockies, 9 P. M. Eastern Standard Time, through WEAF and associated N. B.C. stations. On the Pacific Coast, 8 P. M. Pacific Standard Time, through N.B.C. Pacific Coast | network, SEE AND HEAR THE NEW EVEREADY RADIO SETS @® This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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The Mont POPULAR SCIENCE MONTHLY February, 199 h’s Best Auto Ideas Handy Kinks That May Save You Trouble or Get You Out of It—An Ingenious Opener for WINE \ XA

Fig. 1. Incision in radiator, after the shell is removed, gives access to obstructing particles. HE “neck of the bottle” in an automobile radiator is at the top of the cooling fins or tubes. Any foreign matter that floats around with the water always gets stuck at this point and the result is retarded circulation and a tendency for the motor to overheat. Ordinary flushing. will not remove serious obstructions. But you can get them out by the simple method shown in Fig. 1. Remove the radia- tor shell and with a sharp, strong knife make a curved incision. Then fold out the flap thus formed. Pick out the obstructions with a pointed instrument, push the flap back in place, and solder it. Radiators are made of thin sheet brass so this is easier than it looks.

A Tool Compartment Lock COMMON location for the tool com- partment in the sedan or coach is under the front seat. Usually it is neces- SEAT RESTS ON SHEET METAL

Fig. 2. By preventing lifting of the seat, this lock safeguards the contents of your tool compartment. HINGE

Ten Dollars for an Idea! G. Solomon, of Puerto Plata, Santo Domingo, wins this month’s ten-dollar prize for his suggestion of a garage door opening device (Fig. 3). Each month Popular Science Monthly awards $10, in addition to regu- lar space rates, for the best idea sent in for motorists. Other contributions used are paid for at the usual rates.

sary to raise the front of the seat cushion and pull it forward in order to lift it out to get at the tools. You can fit a lock, as shown in Fig. 2, that will prevent lifting the front edge of the seat cushion and thus prevent the theft or unauthorized use of your tools when the car is stored in a public garage. Both Doors Open At Once IGURE 8 shows a novel fitting for any double garage doors. It is designed so that when you open or shut the door at

= Wy itl BO!

1 a nw) |, NN ST Hy | iit GARAGE DOORS

; /

LT — a OLR AID PAR, oat Ly a ETE —s < ——. : CONNECTING BARS = n= hen srt SEE ; : OFFSET GLOCK Fig. 3. Side and top views of the ingenious device for making double doors open at the same time.

the left in the illustration, the other door will open or shut automatically. The material you need consists of a board of sufficient length, three bolts, a strong iron hinge, and wood screws. As you open the door at the left, a con- necting bar, pulled along with it, opens the door at the right by pulling on the end of the offset block. In closing, the thrust of the connecting bar closes the door at the right. Blowing Starts Siphon N INGENIOUS way to siphon gas from the tank of your car is illustrated in Fig. 4. Insert one end of a rubber tube deep into the gas tank; the other into a container. Then, wrapping your fingers around the tube where it enters the tank so as to make as air-tight a connection as possible, blow into the tank. The pressure will force the gasoline out. You may find that a tighter connec- tion can be made by wrapping your pocket handkerchief around your fingers.|

Garage Doors / f VM Uff ~ NON KW WS i \ \ )

Fig. 4. Blowing into the auto gas tank forces gasoline through a siphon tube into a container, When the Battery Is Dead F THE battery is so low that thecar won’t start, even with the hand crank, a couple of flashlight batter ies will do the trick. Fig. 5 shows how to connect them. Remove the ignition coil wire leading to the ignition switch, and replace it witha wire from one end of the two flash- light batteries connected in series (you must have at least four cells). Then connect the other end of the two batteries to the metal crank case. Crank the motor, and when it starts, speed it up to send a charge through the storage battery. A few minutes’ run will put enough charge in the battery so you can start the car again with the crank.

an , ul ow

Soa g | Wo | = D C7 ae , Ms ° a Ty fie iy

TWO FLASHLIGHT BATTERIE Fig. 5. How to wire two flashlight batteries to start the motor when storage battery is disc

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19 Feber e ere Tre SEATS -™ 8G POPULAR SCIENCE MONTHLY 89 gg ET ee - . Ys 4 fre & re What a cigarette meant there Ten seconds to go— and raw nerves fighting wearied muscles, driving them on into that fearful unknown beyond the wire. What man will ever for- get the steadying solace of that last sweet stolen smoke? What a cigarette means here Two years to go— the slow “ageing” by which tobaccos for Chester- field lose all bite and harshness... Mysterious, this chemistry of Nature! Endless rows of great hogsheads, stored away in darkness; choice tobacco, tightly packed . . . just waiting. And as if on signal, twice each year the leaf goes through a natural “sweat”—steeps in its own es- sences, grows mild and sweet and mellow. Selected leaf, costly patience, endless care — that’s what a cigarette means here. But right there is exactly the reason why Chesterfield means what it does to you! Millions of pounds o choice tobacco from crop are stored away in great warehouses to “age.”

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90 POPULAR SCIENCE MONTHLY February, 199 February, Now for Winter Sports! Thy HEAVY / //) corTon/ ///)\

sprcanen,lt | TAPES

tal \ \ ee > = iil NO" ‘ wh a\ Zs iy \ \\ SameNN\ \ AWA \ AAW \\ SRN \ oan on A \\ \\

A skater with this type of triangular sail Simple type of square skate sail. Hold it experiences the thrill of racing like the wind behind you by the ends of the spreader. 0 > FOOT- STEERING =" AND YOKE Sh : SS ey, S :

BOARD SEAT 14" LONG

SAWED -OFF PORTION OF AN OLD SKI

BOTTOM OF SKATE peen

Y, MY ff, YH ff Yy YY YW

SHOWING POCKE BLOCK sxate. BLock jfjfyyMwyyyni \\oroecre | ...7 ~~ = = FOR HEEL CLAMP OF SKATE 7 *4°x12" fj ig yj Yy WY Uf | WIRE YJ — oe le! SKATE Steered with either hands or feet, this skate ANKLE. {\ The front half of an old ski and two pieces bob travels on ice or hard packed snow. . S of wood make this tricky, speedy coaster. @ * + ays SKATE 3x10°x5-0° Soe TILLER ROPE Lying flat on this tiny ice boat, a boy can control the sail = easily by passing one of his feet through the wire loop. RADIATOR AND ivr es TOP _FORMS === WINDSHIELD ARE = fi eT SHELTER == LIFTED TO ALLOW a7, All| §ROM_winD HOL ACCESS TO UPHOLSTERED Ay 7)))| AND SNOW == INTERIOR se | ol << ea == BODY SSE lh... 15"x 22"x 3-0" - aa eg oe a OVER ALL HINGES OVER AND UNDER THE CROTCH HOLD LINE i The instant the bobber dips, a fisher- Auto sled to take the place of a baby carriage. The wood Set line for large game fish such as pike. man can seize his line on this holder. frame is covered with tin outside and upholstered inside. It unwinds slowly and exhausts the fish. a j4 BENT ON END CLEAT MADE FROM A A I"x A x 16" LIGHT, PLIABLE WOOD

(6, 9 bx1 xi 5, ROPE CLEATS IRON PAIL UNDER- DRAFT Sire

es: z SCREW EYES == (10-REQ’D,) ‘ STRIPS: !5x 2°80" OLD 2 (§-REQD) KETTLE ~--RIVETS A little charcoal or wood in this stove Homemade toboggan. The front end of the bottom strips Iee torpedo to be slung on the end of Se will warm a skater’s chilled hands. are planed thin, steamed or boiled, and bent around a form. a rope toward any suitable target. aaa

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» 199 —— february, 1929 for OUR WORK in wood can be beautiful if you will let a Stanley Forty-Five Plane help you produce flutes, beads, reeds, rounded corners and other finishing touches. This remarkable plane combines seven planes in one in a convenient and practical form. Furnished with a large number of cutters, it cuts rabbetts, - dadoes and fillisters; and also does a great deal of work which ordinarily must be done in a woodworking shop. POPULAR SCIENCE MONTHLY ecorative Voodwor Stanley Plans and Books Stanley offers youa complete series of Plans giving step by step instructions for making 25 useful articles, also a book “How to Work with Tools and Wood” which is in- valuable to the amateur for instructions in woodworking, finishing, etc. Your hardware dealer can supply you with Stanley Plans and Books. If he does not have them, write us. The plans cost only 10 cents each, Books $1.00. Address The Stan- ley Rule & Level Plant, New Britain, Conn. No. 1e—Book Rack No. 10e—Dog House No. 19e—Combination Sail No. 2e—Candle Stick No. 11e—Book Stand and Row-Boat No. 3e—Pipe Rack No. 12e—Smoking Cabinet No. 20e—Combination Kit- No. 4e—Flower Box No. 5e—Table Lamp No. 6e—Toy Automobile No. 7e—Sconce No. 8e—Dinner Gong No. 9e—Bird Houses No. 13e—Kitchen Cabinet No. 14e—Sewing Cabinet No. 15e—Cedar Chest No. 16e—End Table No. 17e—Tea Wagon No. 18e—Model Sailboat chen Seat and Step No. 21e—Garden Seat No. 22e—Garden Trellises No. 70e—Small Tool Chest No. 71e—Large Tool — No. 72e—Work Bench STANLEY TOOLS © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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POPULAR SCIENCE MONTHLY February, 199 pebrust”. Building the “Buckeye State” : If you would like to con- ts struct a model of this famous ' a _ J ce. old Mississippi River steam- boat, you can begin now sim- ply by sending for POPULAR SCIENCE MONTHLY Blue- prints Nos. 94, 95, and 96, which contain complete full size drawings. Use the cou- pon on page 103. This is the fourth article of the series. By E. ARMITAGE McCANN Master Mariner The completed model of the Buckeye State. The original boat was 235 ft. long with a 36-ft. beam and a 5-ft. depth of hold. The model, on a '/1-in. scale, is 1914 in. long. HOSE readers who are building a model of the stern-wheel Missis- sippi steamboat Buckeye State now have the hull complete with two decks and the cabin house on it. Whether one is especially interested in the Mississippi River or not, this model is an attractive one to make because the Buckeye State is typical of the only com- pletely American craft with the exception of the Indian canoe. It represents a type of steamboat evolved to serve 14,000 miles of winding rivers, for the most part very shallow. Even as far back as 1847, according to statistics gathered by Frank L. Coes, there were 958 river boats with How the Bristol board rails are applied. Capt. McCann put them on making in four sections, but time is saved by them in two sections. aside for a time while doing other work. Fix the two forward ladders in position with glue and by driving a pin point through the lowest step. Build safety rails around three sides of the openings. RILL %-in. holes for the forward struts of the hog chains (actually Main Chain No. 2) as shown in Blueprint No. 95 and on page 102 of the January issue. These holes should be 3 in. from the edge of the deck at the positions shown. Bore down until the drill enters the lower deck. Drill a small hole for the chain or rod itself, and make another hole in line through the lower deck. Do not put the struts or chains in position yet. The upper deck may now be placed in position. I fixed mine by driving some pin points into the cabin for it to rest on, with some more above to keep it down. The points need project only 4% in. Brackets glued to the house underneath would make a better job, but perhaps ‘are more trouble on so small a model than they areworth. For the two rails below the handrail of the main deck, cut % in. wide strips of thin cardboard, such as three-ply Bristol board. Glue one side of these, clip one end in position, and stretch them along. This and other similar clipping is most easily done with ordinary spring clothes- pins, the points of which can be sawed to various shapes. Next to be made are the side rails be- tween the two decks and above the upper stern struts. With a sharp-pointed knife or chisel, cut out the openings very neatly, leaving no burred edges. Do the cutting on a piece of glass or another piece of card- board. The lower edge projects 1% in. below the edge of the boiler deck and the up- per edge is 14 in. above the upper deck. On the outside glue thin strips of card- board along the (Continued on page 122) approximately 200,000 tonnage, which D was more than the steam tonnage of Next place the struts supporting the deck, together with their stanchions. Do ¥ Great Britain. Indeed, the history of extension of the cylinder beam to carry These may be entirely fashioned from you Pp Mississippi steamboating is extraordinary _ the wheel (see page 122). An upright post wood, but thin cardboard will make the hat throughout. 4 in. square goes through the boiler deck _ work infinitely easier and will look almost ato We have now progressed in the con- and is set into the cylinder beam. For- as well. I made one piece to surround the That | struction to the point where the third or ward of this there is a strut half that space between the decks and another for the je upper deck is shaped and plank marked. _ thickness, butted to the top of the post the upper handrail, but it would have th This deck must now have square holes and bolted to the inside of the beam. — been better to have made the two in one at | cut in it for the ladders. Thetwoforward Abaftthereisasimilarstrut runningfrom piece as shown in the drawing on page 122. Clayt holes are 3% by % in.; the after one is near the top of the post to the beam about As before advised, use only the very In : more nearly square. Now lay the deck % in. inside of where the wheel bearing _ best cardboard, such as artist’s three-ply will be; and abaft Bristol. To go all the way around would the e that is another from _ take a very long strip, so it can be in two put i1 the top of the post to pieces, from right aft to right forward, rials nearly the end of the amidships. First stretch an. oversized beam. Fit the latter piece right around, holding it in position use. * but do not place it in with glass-headed pins. Mark on it the exper position until the underside of the boiler deck, to get the Clayt wheel is fixed. The sheer; also mark the center of every other other members may of the lower stanchions. Remove it and const be glued and nailed. draw the pattern, noting that one of the & La These ought also to upper posts comes over every second long have barchains, butI lower post. , think they may be Fo: omitted on so small a HE openings at the after end will have ber h model. No. 22 wire, to be a trifle larger than at the other to ‘oh painted black, is used make them balance. Slots will have to be quic for all chains. cut in the lower edges to pass over the torch

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Py) ut of of tol ne ig. st $- to or — Ome SD De hee Oo ea SS I! Oo Oo Ss ‘oe Uw UM 7, i ea & rv, 1929 C& L158 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, electrical and automobile ac- cessory stores have it—or can get it for you quickly. look for the gold-banded, red handle. — FEELING FOR FINE TOOLS IN YOUR BLOOD? Do YOU get a real kick when you pick up a good toolP One that makes working a pleasure? That makes you want to stick at the jobP Well, be set to feel that way when you take up a Clayton & Lambert blow-torch. In a Clayton & Lambert you buy all the exactness and pride that can be put into a blow-torch. You get mate- rials that have proved their value by use. You obtain the result of 40 years’ experiment and invention—exclusive Clayton & Lambert improvements. In construction and mechanism, Clayton & Lamberts are made with an eye for long, efficient service. For instance—the vaporizing cham- ber has an exclusive vein system for quicker, hotter heat. That makes the torch function better and saves money grolECTigg POPULAR SCIENCE MONTHLY C&L 32 This is one of the most popular b!ow- torches we have ever made. It is more expensive than the 158 because it is made for much harder use. It is designed for the man who uses a blow-torch in his daily business and demands not only excellent performance but rugged ability to stand rough handling. 32 contains the most advanced, patented C & L_ blow-torch improvements. 93 on your fuel bills. All fittings are built into the tank by a patented method that prevents their falling 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 orifice has a guard. The slightly higher priced No. 32 has a patented control valve so that you’ll never ruin the torch by a careless twist of your wrist. And when you close the valve you automatically clean out the carbon. The next time you’re in a hard- ware or electrical store look for the blow-torch with a gold- banded, red handle. Be sure of the handle—it marks a Clayton & Lambert. Then you’re getting the largest selling torch in the world. CLAYTON & LAMBERT MANUFACTURING COMPANY, Detroit, Mich. @® This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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Timesavers MACHINE STEEL TURNED TRUE ON CENTERS END FACED OFF TO EXPOSED DIAMOND ~~~ = KKKLWIS | » CAP (PRESSED ON) P——- 4 375 - \ CN FIG. 4 (ENLARGED VIEW) FIG.5 CLEARANCE (COMPLETED HOLDER) Steps in setting a black diamond in a holder for use in dressing grinding wheels accurately. ITH the increasing use of dia- - monds in machine shops, many men have become very familiar with their care and setting. Dia- monds can be purchased either set or un- set. If they are bought set, they usually have to be reset after a time, depending upon the quality of the diamonds and the service to which they are put. The stones used for dressing grinding wheels are what are known as black dia- monds, There are several grades, but it is usually economy to buy a good diamond, as it will give much more return for the money invested. Also, it is well to get a diamond large enough for the work, just as when buying a monkey wrench. Most diamonds are brazed into a steel holder. While brazing has been used with apparently good results for many years, - much attention has been given to other methods. One result of this study has been the use of metals other than brass that melt at relatively low temperatures. This has been carried so far ‘in one in- stance as to make a setting that will soften and release the diamond should it reach 800 degrees F. in service. The method was devised to avoid damaging the dia- mond, yet if overheating in service is like- ly to damage the jewel, as experts main- tain, why will not heating it to 1,600 or 1,800 degrees in the setting also be detri- mental ? This thought led to the development of the method of setting shown in the illus- trations in this column. The diamond is POPULAR SCIENCE MONTHLY Old Bill Says— v= you are forming a radius on the corners of an end mill or a side mill, use a fine grain wheel to get a smooth finish. The average small shop gen- erally has poor equipment for testing a lathe taper set-up; it is safest to take figures at both ends of the work. But don’t use a file to get results! Don’t throw a piece of ma- chinery steel into the tool steel scrap box. If you do, some other mechanic, if not your- self, is likely to get into trouble. When a grinding wheel has a tendency to burn the work, cut notches 14 in. deep with an old file at every inch of the circum- ference. This will help ma- terially to cool the work. A mounted diamond and holders in three stages of completion. No brazing is required. held just as securely and is not heated in setting. The first steps are shown in Fig. 1. A hole should be drilled about 1 in. deep in the machine-steel diamond holder. This hole should be about }% in. larger than the diamond. Into the hole is driven a piece of copper rod, which is allowed to project % in. A hole just large enough to fit the diamond is drilled into the end of the cop- per plug deep enough to receive the dia- mond so that the point is just flush with the end of the plug. Then the copper is carefully peened over the diamond with a small set. Of course, this peening must be gently done to avoid fracturing the stone. The point of the diamond should be kept in the center of the holder as nearly as possible. The holder is next turned on the outside true with the diamond. This is done by centering the rear end of the holder, and running the diamond in a female center February, 199 for Shop Men Soa eee = es Thin, springy spreader used to support parallels under flat work held in a vise. held in the tailstock of the lathe. The female center is made by drilling a small hole in a piece of 44-in. stock held in the chuck and allowing the diamond to true up the hole to fit itself (Fig. 2). A little emery and oil will assist. Next, the end of the holder is chamfered to an angle of about 57 degrees, as shown in Fig. 3. A cap is made from %-in. stock and reamed to press over the turned portion of the holder as shown in Fig. 4. The bot- tom of this cap must be reamed with a reamer having an included angle of 60 de- grees or slightly greater than the angle of the chamfered point. This is so that when the two are assembled the cap will bear on the point of the diamond only. A hole about half the diameter of the diamond is drilled through the end of the cap. The cap is pressed on the holder and its end faced off as shown in Fig. 5 to expose the diamond. This completes the setting, which should take about one and a half hours, after the first trial. The diamond should not project be- yond the cap any (Continued on page 115) Gage for verifying the size of a drill and 7 at the same time \ . H ee ' | iZzsZm : showing the con- Y ie 1Z A centricity of the ; a ; ; —- point, the correct- a a ; ness of the, cutting 4 a n angle, and also the f en SS nae ey Ae | amount of clearance. S| aoe 0

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y, 1929 d - ee Te? ea fl pebruary, 1929 POPULAR SCIENCE MONTHLY 95 , & , ty In the manufacture and maintenance of millions of 1” motor vehicles, Starrett Tools are playing a part of vital importance. Countless thousands of motor t-_e,, mechanics put their faith in the accuracy and last- ‘“\ ing dependability of Starrett Tools. If you, too, appreciate the value of Starrett stand- ~~ ards of quality and workmanship, be sure and ask your dealer for Starretts. Look for the name on every © tool. Ask us to send you Starrett Catalog No. 24“W" containing full descriptions and prices of over 2500 tools. THE L. S. STARRETT CO. World’s Greatest Toolmakers Manufacturers of Hacksaws Unexcelled Steel Tapes—Standard for Accuracy ATHOL, MASS., U.S. A. Use Starrett Tools 2259 © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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ATHE work, as a rule, is balanced statically. In large and ponderous castings revolving at slow speed, this is all that is required to coun- teract the gravitational pull which might otherwise cause uneven running of the spindle under the changing eccentric load. Balance, however, is not always the only point which has to be considered. With very heavy work, the weight of the work itself, whether it is eccentric and unsym- metrical or not, becomes a factor when it is large in proportion to the size of the lathe. What is meant is shown in Fig. 5, page 114, at A. The heavy weight of the large casting causes a bending moment in the spindle, which is thus deflected downward and in turn disaligns the work. The spin- dle itself may spring slightly; certainly there will be “give” in the threads of the spindle nose, as well as in the various parts of the chuck or in the web of the faceplate. What actually happens is that the part revolves around an axis of which the front portion is at an angle to the rear portion, producing an effect somewhat similar to that of a flexible or universal- joint shaft. Many exasperating errors in costly jobs are due to this condition with- out the cause being recognized. Even where it can be applied, the indi- cator does not show this kind of error because the plane in which the faceplate or chuck revolves, while inclined at an angle to the vertical, remains parallel to the traverse of the compound rest on which the indicator is held, as may be seen from the diagram at B, Fig. 5. Even where the work already has a true cylin- drical surface that can be indicated, this error usually goes unnoticed because, es- pecially with large work, the mechanic applies the indicator to the side. So used, the indicator will show eccentricity, but it cannot show sag or deflection of the spindle. The difference can be seen in Fig. 4. It will be noted that while the movement of the eccentric piece at A must be regis- tered no matter which way the indicator is applied, the piece held on the deflected spindle at B describes a path concentric with the spindle axis at that point, and ’ length from the front POPULAR SCIENCE MONTHLY Much ingenuity is of- ten required to set up a heavy and awkward casting in a small lathe. the indicator will therefore be at rest. As the sag is only downward, the error can- not be seen by running the indicator along the side of the work, as at a in diagram C. It should, instead, be run along the top or bottom as at b. Now, it might be argued that as the indicator run along the side does not show the existence of any sag, so no trouble will result by applying a tool under the same circumstances. This may or may not be true, There will be no noticeable error if the diameter to be turned is large and the tool is applied almost exactly central. Particularly with bores, how- ever, the diameter is often comy .ratively small ev _ in large work, And in bores as well as outside turns, ihe tool is usu- ally applied below or above center. Some of the result- ing possibilities are shown, in the dia- grams and table of Fig. 2, where it will be seen that the error caused by having the boring tool 3%; in. off center in a 1-in. hole results in a taper of .0007 in. in a bore 6 in. long, even with a sag of only .0005 in. per running inch. ITH the sag in- creased to .001 in.—or less than 1% in. over the entire 15-in. spindle bearing to the end of the work— the difference rises to .0015 in., which is more than enough to spoil many a piece of work. It is interest- ing to note, and will sometimes be useful to remember, that with the tool above center as at A, the February, 1939 Turning Oversize Work in a Lathe How to Prevent Sagging—Saving Strain by Use of a Faceplate in Place of a Chuck—Steady-Rests By HENRY SIMON bore will be tapered out. ward, while it will be larger at the inner end when the tool is below center, as indicated in Fig. 2 at B. Now the evident remedy for spindle sag would be to use a heavy enough lathe for heavy work. This is excellent advice, and would be even better if it could al. ways be followed. But most of us are not in the fortunate position of being able to pick the right tool every time, and the faithful little old lathe will have to con- tinue handling many a job that stretches its capacity. There are ways out of almost everything, however, ‘and -so there are ways out here. With smaller holes, the use of an ex- pansible reamer (Continued on page 118) Setting up a casting on which a “stub” or extension has been provided and turned to a suitable diameter to allow a steady-rest to be used. i l--||

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1929 POPULAR SCIENCE MONTHLY 97 february, 1929 7 4 ‘ Accuracy Grows More And More Important In many cases, today’s product must be held to limits closer than one thousandth of an inch whi*re yester- day’s passed muster at less -xacting standards. Why? Simply because to- day’s manufacturer has learned that faster and more profitable produc- tion follows close in the wake of smaller tolerances,or working limits. All along the line, fine measuring tools are needed to make high pre- cision standards possible. Manu- et “= 4 CX tee facturers, tool-emakers, and mech- heh her ae bbb anics everywhere rely for this No. 300 _ work on Brown & Sharpe Tools, known the world over for their . quality and unfailing accuracy. The tool shown above is Bevel Pro- ae tractor No. 496. Get a copy of Cat- eee ScrtSatatsestonattend alog No. 30, describing this and over Combination 2300 other Brown & Sharpe Tools, Meee Boao! from your hardware dealer. Or write us forone. Address Dept. P.S., Brown & Sharpe Mfg. Company, Providence, Rhode Island, U.S. A. (BS o WORLD’S STANDARD OF ACCURACY BROWN & SHARPE TOOLS © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. Micrometer = No.8

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98 POPULAR SCIENCE MONTHLY February, 199 a , ' Just notice the fine skins of men who use y You can't lose this cap! The Eve as that leaves FAackEs Texture! Lather of close texture is lath- er that holds a maximum of moisture. Williams lather is lather of the closest texture. It holds 10% more moisture, by actual test, than any other we know of. Lather of close texture is super mild. It’s the thin, open lather that roughens and stings. Texture—moisture—mildness! Williams gives a new glimpse of shaving comfort to the man who uses it for che first time. v v v The drug clerk knows. Lis- ten: “Oh, yes, sometimes they change . . . . but they all come back to Williams!’’ : THE J. B. WILLIAMS COMPANY, GLASTONBURY, CONN.—~MONTREAL, CANADA. Next time say ‘Williams Shaving Cream. Afterwards find out how perfectly AQUA VELVA completes the shave. Made just for that. ag HAVE just been looking at two or three paint spray guns,” a friend of mine remarked to me not long ago. “They sell at less than $40 and look excellent. I would like your opinion as to which one it would be best to buy for painting the three large barns on my farm.” His was an innocent request for infor- mation typical of a thousand and one questions being asked by amateur paint- ers and decorators who wish to take advantage of the spray guns being sold for home use. And it is not always easy to obtain informative answers. The would-be purchaser is told that they are great labor-saving tools for the application of paint, lacquer, enamel, varnishes, and other decorative and pro- tective coatings. He has to explore a bit for himself before he can hope to find the limitations of the half a dozen or more types of spray guns. Let us see just how the spray gun works and we shall better understand what constitute reasonable expectations from this most useful tool. The spray gun is a tool through which a stream of air and a stream of paint, lacquer, var- nish, or other liquid are passed; the air breaks up the liquid, atomizing it and projecting it upon the surface to be coat- ed. Some types permit the atomization to be controlled exactly as to uniformity and volume; others allow only a partial control. In the simplest type of gun the paint or other liquid is supplied from a con- tainer near the nozzle by siphonage. One end of a small tube or pipe is inserted into the liquid and its other end opens just back of the nozzle hole in the end of The spray gun above is of the professional type used with a large pressure-feed outfit. The one at the left is of the siphon-feed type and has a small glass con- tainer for the paint. Choosing a Paint Sprayer F. N. VANDERWALKER Describes the Various Types of Guns” Available for Home Decorating the gun. When a stream of air is projected past the upper open. ing, the liquid rises through the tube; the air stream then atomizes and projects it on the surface being painted or otherwise deco. rated. A study of the tabulation on page 100 will show that the types marked A, B, C, and F use the simple siphon system, In a second type of sprayer the materia] is contained in a cup above the gun or in a large container from which a hose leads to the nozzle, and the feed is by gravity, A third type is fed by pressure. The material is carried in a tank lower than the gun and a pressure of from five to The kind and amount of work you wish to a do govern your Z\\ \\\} choice of a spray gun. thirty or forty pounds is applied in the tank to force the liquid to flow up into the gun. It is obvious that a heavy liquid, such as paint weighing from fourteen to twenty pounds a gallon, will require an air stream at higher pressure to lift it to the gun and to atomize it than a wood stain or thin lacquer which does not weigh nearly so much. Consequently, it is well to thin the heavier liquid with from ten to twenty-five percent of tur- pentine, benzine, or lacquer thinners in order to make them spray to best advan- tage when the air supply is limited—and, indeed, sometimes when it is not. Generally speaking, there are two types of guns. One requires a relatively high pressure—from forty to sixty pounds— and less volume of air than the other. The ports or holes in the nozzle of high- pressure guns are smaller than in the low- pressure types, which use a much larger volume of air at a pressure of about twenty pounds. The three air supply factors are pres- sure, volume, and duration. The capac- ity of a spray gun of any type is limited by these factors. Spray guns such as those marked A, B, C, D, and E, which are supplied with air by means of a hand or foot (Continued on page 100) rk, Panna? 2a

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ount our gun, | Rudi ctiaclialiainl POPULAR SCIENCE MONTHLY J New Features of 1929 Model found exclusively in the “Delta”? Handi- Shop, in addition to the many regular exclusive advantages, make this shop one of the finest values in the workshop field. A few of the new improvements are: New Delta Miter-Gauége (with many new features). New Circular Saw Adjusting Lever. New Delta Adjustable Rip Gauge. Larger Circular Saw Table. 1/3 H. P. Motor. Larger Triple Foundation Lathe Bed. 1/2 inch capacity Drill Chuck. For full details, send coupon below. Make the Things You Have Always Wanted to Make With this convenient, practical workshop. It’s eo easy and so quick. Save money on repair work. Earn money in your spare time. Complete instructions furnished. With each Handi-Shop is included, at no extra cost, complete set of working drawings. Below are a few of the hundreds of articles you can make in a jiffy with a Handi-Shop. Blue Prints Included DOES EVERYTHING FROM BUILDING FULL-SIZED FURNITURE TO TURNING 36’ TABLE LEGS Note the two-shaft mo- tor that permits two or three operations at one time—the heavy Triple Foundation U-shaped Lathe Bed (no rods)—the practical arrangement of the Circular Saw that permits the cut- ting of large lumber without interference—the Improved Tilting Tables on the Circu- lar Saw, Sanding Disc and Jig Saw, with many exclusive features. Has auto- matically oiled bronze bearings and is completely assembled on heavy veneered wood base. This combination of advantages, plus many more, IS FOUND EXCLUSIVELY inthe DELTA HANDI-SHOP! No wonder even last year’s Handi-Shop was an outstanding value. And now, with the many additional exclusive features of the new 1929 model, this shop is in a class by itself—above all comparison —at a new price that is surprisingly low. 10 DAY TRIAL in Your Own Home without obligation. See how PRACTICAL, how . EFFICIENT is this sturdy, full-sized machinery under actual working conditions. Study its many exclusive advantages. You will find the Handi-Shop complete with all necessary equip- ment for Circular Sawing, Woodturning, Jig Sawing, Sanding, Drilling, Grinding and Buffing. Zz Easy Terms Then if you decide to keep the Handi-Shop, you can have your choice of three convenient methods of paymen Coupen at once for Free beautifully illustrated literature giv- ing complete description of the New 1929 Model ® DELTA SPECIALTY CO. 8 1661-67 Holton St., Milwaukee, Wis. (Check material desired) This TWO-SHAFT motor is THB ractical motor for the workshop. Permits you to carry on two or three important operations at one time — without continually dismantling the set-up. All DELTA UNITS have 36 in. lathe capacity be- tween centers . This Heavy Triple %& Foundation bs haped Lathe Bed not rods or rails) is GUARANTEED not to spring or chatter. WRITE FOR THIS oe \ VALUABLE BOOK crammed full of practical in- formation on how to con- struct useful and decorative objects. Helpful whether you ‘own workshop or not. Com- plete directions, illustra- tions, diagrams. Contains important information on “finishing.”’ If you want this book, send 10c, which merely covers cost of mailing. See \ coupon below. see Se ee we Dept. B-29 ane entl-Geee, Wh te ney ee [[] Please send. without obligation, FREE illustrated tages and new features. Also full details of the 10 Day Trial Offer and Convenient Payment Plans. Payment Plans. literature describing new 1929 Model Delta Handi- Shop. Also full details of 10 Day Trial Offer and Easy EL co. ® Please send me copy of “How to Make Things with D TA SPECIALTY ~ : O a Workshop.” I enclose 10c to cover cost of mailing. 1661-67 Holton St. Milwaukee, Wis. Dept. B-29 pe DBBIIIE. «2 once. scccnsscs :0s-080s-cnstensnscasenscasbnbecs © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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A Cheney NAILER Will Make the Day’s Work EASIER <6 Save yourself the labor and ex- pense of building extra scaffolding on the job by using a NAILER, the wonderful Cheney nail-holding hammer. A Cheney NAILER takes a lot of the grief out of hammer work. AI- most any nail fits perfectly in its nail-holding niche. Then with a single blow you can set the nail wherever you want it. The extra long reach obtained is what saves your time. The weight of the ham- mer releases the nail. This easy one-hand nailing will save you many bruised fingers as well as labor and time. Trya handy NAILER. Every 16 oz. and 20 oz. Cheney Curved Claw Hammer has the nail-holding ar- rangement.

POPULAR SCIENCE MONTHLY February, 199

Choosing a Paint Sprayer (Continued from page 98) pump or a very small electric motor, necessarily are limited in air volume and air pressure. The hand and foot pump types also are limited in the duration of the supply; that is, the air supply is not as steady as it is with an electric motor. 7 decorating surfaces of a limited sige With the smaller guns it is impracticg but not impossible to paint large gy. faces. Spray guns supplied with air by electric motors—those having a tiny

a ” T {S G ypes Oo pray uns ‘ d Their U * Air Pres- Regula- Materials Surfaces Practical Tope] Friee | gusty | owe | 7 | "thee Handled to Finish A $2.00 Hand Low | Siphon | Limited |Paint, lacquer,/Furniture, to uch-up pump enamel, var-| work, radiators, pic- nish, stain,) ture frames, auto sizes fenders, all small objects B $4.50 Foot Low | Siphon | Limited Same Same to pump $15.00 Cc $4.50 Vacuum | Low | Siphon Less Same Same cleaner limited $35.00 | Very small) Low | Siphon | Certain Same Furniture, radiators, electric and small exterior bldgs., motor pressure automobile refinishing, cabinet and interior _ house trim E $40.00 | Very small} Low | Siphon | Certain Same Same electric and motor pressure F $100.00 4% to % | High | Siphon | Certain Same Same, also larger surfaces to m.P. and $150.00 electric low motor . G $300.00 1 H.P. High | Siphon, | Certain |All materials |Furniture, automobiles, $600.00 | and larger| and | gravity, that can be| interior trim, floors, $1,000.00} motors low | pressure brushed and| walls, exterior of and gas others houses, barns, metal, engines -brick, concrete, shin- gles, ete. E

Because of these limitations, the prac- tical usefulness of these hand and foot pump sprayers and the small motor types of spray guns is mainly for coating chairs, tables, radiators, and wicker furniture, for touching up automobiles, and for AIR TC F SPRAY gc AIR TO PAINT TANK Paint spraying outfit with air compressor driven by an electric motor. It can be used with either spray gun shown on page 98.

motor mounted directly on the gun or located separately near by—have greater capacity than those which depend upon hand or foot pumps. It is practical to use them for painting a garage, fence, or small room interior, and, of course, an auto- mobile, but they will hardly serve for painting a large house or a barn. Among the small motor- driven spray guns there are, in general, three types. One mounts the motor on the spray gun handle and depends more upon a large volume of air at low pres- sure for atomizing the material than upon a smaller volume of air at high pressure; from twenty-five to thirty pounds pressure is_ the maximum of this type. The second type is that using the siphon principle gun and having a very small electric motor as a separate unit. These guns also come within the low- (Continued on page 107) GUN

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

snow! froze!

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ed size, Tactical rge sur. air by @ tiny oyvrvU hhCCS[ST.LUC!C(‘ét( G 1 or ater pon nall ito- for pebruary, 1929 Bnon for Shooting Snowballs By HI SIBLEY A length of old downspout or stovepipe forms the barrel of this unusual snowball howitzer. § THE winter campaign in the War of the Vacant Lots becomes more furious, defenders of the fort will need more powerful artillery. By constructing a snowball howitzer as shown, they can hold off a strong enemy force. The power is obtained from % in. wide rubber bands cut from a discarded inner tube, preferably one which retains considerable elasticity. A coil spring is slipped over the broomstick before the firing mechanism is assembled to take up the shock of the plunger when firing. Upon the neatness of the firing mecha- nism depends the efficiency of the howitzer. A ¥-in. thick, hard wood block shaped as indicated forms the foundation of the trip. A rubber band holds the trip block in position until fired, and a stop at the bottom prevents the band from pulling the block too far forward. A cord is attached to the lower end of the block. For ammunition, pack your shells from moist snow, but remember that the Com- mittee on Armaments of the League of Vacant Lots absolutely outlaws any snowballs that have been soaked and frozen. RUBBER BANDS v2" WIDE } CROSSBAR . ee pithy " METAL OR’ LEATHER STRAPS BOLT Fw y= HARD WOOD te BLOCK =. NG Ss ais = | TNAIL “STO RUBBER BAND TRIP MECHANISM PLAN OF TRIP MECHANISM How the howitzer is made. Pulling the string Teleases the ingeniously simple mechanism. a Your only way / to gett “YANKEE” f Efficiency / Three sizes of bits with } 4. C] Gaeene mechanics . know the only way | to get “YANKEE” effi- ' ciency is to get “‘ Yankee” Tools. Amateurs and | handymen can _ profit | by that knowledge... . _ Safe rule always before you buy to see that “Yankee” is on the tool! “Yankee” Spiral Ratchet Screw-drivers are the standard of the world. oe =z nal a Aare % — ~~ ~ ~— —_ —_ _ mt ~ = ~~ ~ — — = : Right and left spi- r right and left ratchet, and r' adjustments, |' Up or down is the same to ‘‘Yankee”’ No. 130-A. Just push! This spring in the handle, with the “Yankee” Spi- ral, does the work. Great in tight places ...one hand drives, or draws, screws. To drive screws, just push. The ‘Yankee’ Spiral does the work. Smooth! Easy! Shift to left-hand motion and you draw screws like a flash. Another touch gives you ‘‘Yankee” Ratchet movement for occasional heavy screw- driving. Make sure! “Yankee” Tools may be copied in looks but not in workman- ship. Ask your dealer for “‘ Yankee”’ Tools. They stand up, give long service, are cheapest in the end. No. 130-A is the “ Yankee” Quick Return. Spring in handle brings it back for next stroke. Like a thing +*@+@:+@+ @:-O+erei-0 Chuck and Drill Points enable you to drill holes with drivers. Eight drill points, *% to #4 (same as j ! 4 i for “Yankee” alive! ane blade In P h Drills) it lo | 4 chuck to fit spi- screw-slot. eaves one ral drivers, sold separately in w box, ' hand free to hold work. Three bits. Price, $3.45. No. 30-A is the standard style “Yankee” Spiral Ratchet Screw-driver, with- out spring in handle. Three bits. Price, $3.00. Made also in Heavy and Light patterns. "YANKEE" TOOLS Make BetlOv Mechanica ee eg ee North Bros. Mfg. Co., Philadelphia, U.S. A. Send Tool Book Mentioned in Popular Science Monthly, Mail Coupon Get “Yankee” Tool Book with action pictures showing how the ingenuity of “Yankee” Tools will help . you make things, savin your time an labor.

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HERE’S THE BLADE YOU WANT. When you buy hack saw blades you can be assured of the best blade money can buy, when you ask for STAR. For faster accurate cutting with practically no breakage, the STAR BLADE is unexcelled. Special tempering of each blade gives strength and cutting qual- ities that are unsurpassed. The uniform excellency of each blade has won a world wide reputation for STAR HACK SAWS. Let us send you free working samples. CLEMSON BROS., INC. MIDDLETOWN, N. Y. Makers Since 1883 POPULAR SCIENCE MONTHLY February, i9y A comfortable rocking chair salvaged from the one in Fig. 2. Fig. 1. ern or antique, can be salvaged in many cases by replacing the up- holstery or by substituting upholstery for rush, splint, or other types of seats. It is surprising what can be done with an apparently hopeless-looking chair. Some can be made fully as good as new; others, less attractive in their original de- sign, can, nevertheless, be nade comfort- able and serviceable for use in a spare room, a child’s room, or other room where extra seats are needed. The chair shown in Fig. 2 was junked until the writer salvaged it to serve as an illustration of what can be accomplished in repairing a particularly poor specimen. Figure 1 is the same chair with all of the old willow removed and the old back re- placed by a “‘slat and spindle”’ back. The new seat is of the bar and spring type, pieces having been added to form an apron to prevent the springs from show- ing underneath. Note in Fig. 3 how the springs are tied to keep them in position. In Fig. 4 is shown a very important part in the reconstruction of seats. Two layers of the best grade of burlap have been stretched over the springs and tacked to the apron. A %-in. wooden rod is nailed to the top of the apron to form a “roll,’’ which holds the seat filling in position and retains the shape given the new seat. This “roll” also may be made with rope or with flax tow twisted into a roll and similarly nailed. [ J errr antic chairs, whether mod- Fig. 3. The bar and spring method of uphol- stering a seat. Note how the springs are tied. Upholstering Old Chairs Fig. 2. If this chair could be repaired, js any chair beyond hope? The next step is to fill the seat with g good grade of flax tow. There are a num. ber of materials with which seats may be filled, but tow is preferred by the writer, who has removed upholstery fillings of every description from old furniture and has found none to be in as good condition after a number of years of hard service as the tow. I have removed tow that was known to be well over a hundred years old, knocked the dust out of it, pulled it Fig. 4. The springs are covered with two layers of burlap and a rod is added to form a “roll.” apart to “fluff it up,” and used it again in the same job; it was as good as when new. Fill the seat well and evenly; don’t skimp the filling. The reason for all chairs is the seat, which should be comfortable. Three pounds of tow were required to fill the seat as shown in Fig. 1. Stretch burlap or any kind of cloth over the filled seat and tack it to the apron; this gives the seat the form desired. Now is the time to clean and refinish the chair. If this part of the job were the first to be done, it would more than likely have to be done over again after so much handling: The chair illustrated originally had a clear varnish finish; it was refinished with mahogany varnish stain. Figure 1 shows it a better and more comfortable chair than when new, although with this particular kind of chair it is hard to decide where it belongs; it is being used now in a bedroom. After the job is refinished, the final cov- ering is put on. (Continued on page 110) a © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. ce are tw The | selves; back i ojec fad fi copies sides stamp 0) ul IO Senc underl: Stre City

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vith a num. ay be Titer, , and ition ce as years ed it i on ae al le. february, 1929 Blueprints for Your Home Workshop UR blueprints can be obtained for 25 OP cents a sheet. L.. some cases there are two or three sheets to one subject. The blueprints are complete in them- selves, but if you wish the corresponding back issue of the magazine in which the oject was described in detail, it can be had for 25 cents additional so long as copies are available. Other subjects be- sides those below are to be had; send a stamped envelope for the complete list. Popular Science Monthly, 250 Fourth Avenue, New York Send me the blueprint, or blueprints, I have underlined below, for which I inclose Sa aa Described No. Title inIssuesof Price 1. Sewing Table Feb., °22 25c *Mar., ’22 25c 2. Smoking Cabinet *May, 22 25c 5, Kitchen Cabinet 15. Workshop Bench Jon., 23 25c 97, Kitchen-Cabinet Table Oct., 23 25c 30. Tool Cabinet, etc. Jan., "24 25c 31. Sewing Cabinets Feb., "24 25c 37. Simplified Bookcase Dec., °24 25c 39, Salem Chest of Drawers *Feb., "= 25c 43. Four-Tube Receiver *jJuly, "25 25c (battery operated) 44-45, Pirate Ship Model *Feb., "26 50c 46-47. Galleon Ship Model May, °26 50c 48. Sailing Yacht Model *July, °26 25c 49. Broom Cabinet Aug., °26 25c 50. Airplane Model (Rise-off- ground tractor, 36in.) ‘*Sept., °'26 25c §1-52-53. Clipper Model, Sovereign of the Seas *Oct., °26 75¢ 54. Five-Tube Radio Set *Oct., ‘26 25¢ 55. Five-Tube Set—Details ‘*Oct., 26 25c 56. Bird and Animal Toys Dec., °26 25c 57-58-59. Constitution Ship Model (‘‘Old Ironsides’’) Jan., “a7 75¢ 60. Welsh Dresser Mar., ’27 25c 61-62. Viking Ship Model Apr., °’27 50c 63-64. Toy Motor Boat, 29 in. long hull May, ’°27 50c 65. Six Simple Block Puzzles June, ’27 25c 66. Ship-Model Weather Vane Aug., ’27 25c 67. Toy Model of Lindbergh’s New York-to-Paris Plane Aug., ’27 25c 68. Magazine-Rack Table and Book-Trough Table Sept., °27 25¢ 69. Flying Model (3 ft.) of Lindbergh’s Monoplane *Oct., °27 25c¢ 70. Console Radio Cabinet Nov., °27 25c 71, Console Cabinet—Details Nov., ’27 25c 72. Doli’s House Dec., °27 25c 73. Doll’s House Furniture Dec., ’27 25c 74-75-76. Santa Maria Ship Model, 18 in. long hull Dec., °’27 75¢ 77. Simple Pier Cabinet and Decorative Wall Shelves Jan., ’°28 25c 78. Simple Treasure Chests Feb., ’28 25c 79. Electric Radio Set Feb., . ’28 25c 80. High Power Unit for Elec- tric Radio Set Mar., ’28 25c 81. Low Power Unit for Elec- tric Radio Set *Apr., °28 25c 82. Simple Single-Stick Air- plane Model (30-in.) Mar., ’28 25c 83-84-85. Mayflower Model Apr., ‘'28 75c 86. Racing Airplane Model (35-in. twin-pusher type) May, ’28 25c 87. Seaplane Model (30-in.) June, ’28 25c 88. Simple Modernistic Stand; Modernistic Bookcase Aug., °’28 25c 89-90. Bremen Scale Flying Model (3-ft.) Aug., °28 50c 91. Modern Folding Screens Sept., °’28 25c 92. Simple Baltimore Clipper Ship Model (8 in. long) Sept., ’28 25c 93. Three Modern Lamps Oct., °28 25c 94-95-96. Mississippi Steam- boat Model Nov., ’28 75c 97, Modern Radio Set in One- Tube Form Nov., °’28 25c 98. Modern Radio Set in Two- Tube Form Dec., °28 25c 99. Modern Electric Radio Set in Four-Tube Form Jan., ’29 25c 100. Modernistic Book Ends, Book Shelf, Low Stand Dec., ’°’28 25c 101. Toy Fire Engine, Sprink- ler, Truck, Tractor Dec., °28 25c *Magazine only out of print. PIR cs dds eae aneeeiamamsd anna hiemedeachdbiaaned nd (Please print name and address very clearly) TNR. cccccvcscsbescsscccoses ccccee ecccccccccce evecece City and State..... TE eer FEIT rere wena POPULAR SCIENCE MONTHLY 103 Buy Later First Make This Remarkable Test for 7 days . . . Prove This Unique Shaving Cream’s Supremacy . . . Buy Only if Convinced. Mail Coupon Now. GENTLEMEN: Most manufacturers clamor for im- mediate sales. “Buy this!” “Buy that!” they urge. But we have found success in urging men not to buy. Rather, to find out at our expense if they like our product. For if they do, they’ll buy, and they’ll tell others. Such is the basis of the spectaculare success of Palmolive Shaving Cream. The great majority of men who make- our test become regular users. Remem- ber they, like you, were wedded to some other shaving cream before. The coupon is for your convenience. Even though you customarily do not use coupons, please send this one in. In fairness to yourself and to us. How it was discovered When we set out to make a shaving cream, we asked 1000 men what their wishes were. They gave us four objec- tives. Our great laboratories set to work. Time after time we tried, 129 in all, before we got the formula that brought success. To the 4 things men asked, we added a fifth. Today we believe Palmolive Shav- ing Cream is supreme for shaving com- fort. Men tell us no other compares. These 5 Things The things you get in your 7-day test of Palmolive, are things you have long sought: 1, Multiplies itself in lather 250 times. 2. Softens the beard in one minute. 3. Maintains its creamy fullness for 10 minutes on the face. 4. Strong bubbles hold the hairs erect for cutting. . Fine after-effects due to palm and olive oil content. Now we ask a test No doubt your present shaving prepara- tion suits you—still there may be a better wn ’ way. If there is you want to know it. So won’t you let us prove, on your face, how excellent this unique product is? It’s up to us to prove our point, you’ve lost noth- ing if we fail. Please mail the coupon now. 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 39 stations associated with The National Broadcasting Company. With the new unbreakable Bakelite top. To add the final touch to shaving luxury, we have created Palmolive After Shaving Talc—especially for men. Doesn’t show. Leaves the skin smooth and fresh, and gives that well-groomed look. Try the sample we are sending free with the tube of Shaving Cream. There are new de- lights here for every man, Clip and mail the coupon now, 4240 [fF 7 SHAVES FREE and acan of Palmolive After Shaving Talc Simply insert your name and ad- dress and mail to Dept. B-1595, Palmolive, 3702 Iron St., Chicago, Ill. Residents of Wisconsin should address Palmolive, Milwaukee, Wis. (Please print your name and address) —————————=— a

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104 Saving Time en screws jon 4 ensivV produc om delayt screw? do not infer th eads guto- n . e pene drivins- — ER . uni- with — re of bi nem a n yo, Moai. Uae aad will sav ductio™ money ‘TIRE BOLTS STOVE BOLTS ~*~ WOOD SCREWS MACHINE SCREWS AMERICAN SCREW CO. PROVIDENCE ,R.1.,U.S.A. Western Depot: 225 West Randolph St., Chicago, IIL “Put It Together With Screws” REMINDS Gs POPULAR SCIENCE MONTHLY how experts like my little friend Aram Abgarian, who won the Stout Indoor Trophy with a flight of 353.6 seconds, carve the propellers for their record-breaking models. The first requirement is a good sharp pocketknife. The next is to have suitable material for the blank. In the majority of cases a. beginner will use clear, soft ‘white pine unless he is making an espe- cially light model with a framework of balsa wood, in which case the propeller also may be whittled from balsa. The ideal propeller is of the “true screw” or “true pitch” type; that is, it has a uniform pitch throughout and there- fore insures the utmost dynamic thrust and delivers the maximum power. A long narrow blade is better than a short stubby one. A good ratio for large “‘props”’ is six to one in the relation of length to width, although wider propellers are often used with good results, the ex- treme being represented by a ratio of four to one. Generally speaking, the widest part ot the blades should occur about two thirds the length from the hub. This is the simplest and most effective way I know for a beginner to at- tain a true screw prop: Take an oblong blank and square it up on all sides. Assum- ing it is a right-hand prop desired, draw accurate diagonal lines on both faces of the block (Fig. 1). Where the diagonals cross each other, drill the hole for the propeller shaft. Next saw or cut away the wood follow- ing the face diagonals, but leave an ap- proximate width of 1% in. at the hub. The blank will then resemble Fig. 2. Draw diagonals on the end of the blank as in Fig. 3. They must be exactly EGINNERS in airplane model making always wish to know \ hittling Model Propellers| Methods Used by Prize Winners in Miniature Aircraft Contests—Bending Bamboo—Other Hints By A. L. JACKSON opposite from each other on each ead; that is, the lines run right-hand from bot- tom to top on one end and vice versa on the other end. Hold the propeller blade in your left hand and, starting at the hub, carve away from you. You are really carving to those end diagonals you have drawn. Then, on the same face but in opposite diregtion (just turn blade around in your me 5 carve to the other end diagonal (Fig. 4). . Put a slight “‘dish” or camber in the blade at this stage. Use fine sandpaper and hollow slightly the full length of the blade, but not too deep. After that, carve the other side to conform to the hol- low on the front (Fig. 5). Sandpaper the blades down until you can see light show- ing faintly through them when you hold the prop up to a window. Then, and then only, should you round the tips. A coin may be used as a template for mark- ing the ends. A special blank is not essential for a toothpick propeller. Just slice off the tip edges of a prop made as described. This will leave a prop with a very narrow pointed blade as in Fig. 7, slightly rounded at the extreme tip. It is a very fast prop and often used on speed models. The efficiency of the prop varies from nothing at the hub to a maximum at the tips. Weight is an important factor in good fly- ing models; and, since the hub is worth- less and offers a hindrance to gliding, cut away as much of it as possible on the front or hollowed side, not the back (Fig. 6). This will not injure the looks of the prop and will reduce its weight and increase the efficiency. However, you must leave at least 4 in. in thickness at the hub or you'll break your (Continued on page 105) nc

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IAry, 1929 per the at, 0l- the Ww old nd rk- a Lip February: 1929 a Whittling Propellers (Continued from page 104) blade in the process of winding the motor. Instead of using a pencil to lay out a balsa wood blank, use a metal-edge rule and a knife. Sink the point of the knife into the soft wood for the diagonals on the face of the blank. Be to leave the hub wide enough so that it will not break while you are doing the actual ing. You can trim or tear away the wood outside the diagonals and have a straight true to carve to throughout the operation. The propeller shaft is of vital importance. It must be neither too long nor too short and must be absolutely true or it will cause vibra- tion. Use shafts from 1 to 2 in. in length on small models and from $ to 4 in. on larger props of 8 in. or more. Pass the shaft through the hub after install- 5 ON UPPER AND E DIAGONAL LINES "FG ~ r ' ‘ ‘ ‘ ’ ’ ‘ FIG.2 DA~ ' LEFT END MARK RIGHT END MARK” END MARKS ARE DIAGONALLY OPPOSITE FIG.3 BLANK, CUT TO LINES == = mone = - ress = FIG.7 TOOTHPICK BLADE Steps in marking and carving a propeller. Note that the concave faces are the first to be shaped. ing a washer and see that the cut-away portion of the blade is the front. Bend a square U in the end of the shaft as in Fig. 8, assuming you have already bent a rubber hook on the other end. Give this U a wrap or two of silk thread soaked in an ambroid type of cement and pull it back into the hub with the point of the U down and towards the cutting edge of the prop; tap it gently but firmly in place. A propeller bearing that I find efficient and practical is made from a piece of a cotter pin (Fig. 9). A small pin is used for little models and a larger one for big models. One end of the piece is flattened but not made too thin, and a hole is drilled in it for the propeller shaft. The hole can be made by driving the point of a phonograph needle through it. Cut the piece down as small as practical in length and bend it as shown. Two things should be remembered: First the only point of contact between the blade and the thrust bearing should be at the hub. If the blade strikes at any other point, the prop will be sluggish in action. Secondly, it is of equal importance to see that the thrust bearing is not too high or low. The motor stick will bend and perhaps break if the bearing is too high, and if it is too low the motor will not clear the stick. The best method to determine the height of a thrust bearing is by experiment. The precautions just outlined apply also to the rear rubber hook on the opposite end of the motor stick. I (Continued on page 106) POPULAR SCIENCE MONTHLY @ This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. "ig ag ae You can SEE this BEFORE you'Buy it! | Ask your local dealer to show it to you"He _| probably has it in stock. Examine it. Its’ quality stands out. Made by a maker of good tools since 1888, you take no chances, Your dealer will guarantee it. . We'll back him up. Note these features: Power Unit A No. 1040 1/4-inch Electric Drill; easily removable for use-as-a portable drill. Lathe Unit Practical and sturdy.’ Used for years on our foot power lathes. Adjustable Tee Rest and Tail Stock can be locked at any desired points.* Capacity, 12 inches between cen- ters; 5 inch swing. Saw Table Adjustable to cut from 0 to 1 inch: Made of wood, 9x10 inches, with steel inset. and guard. .Two saw guides-for ripping and for cross-cutting or mitering. Polishing and Grinding A 4 inch Grinding Wheel with 1/2 inch face and a 4 inch Buffing Wheel. Can be used in lathe or portably. . Disc Sanding Sanded Disc, with 4 inch face. Emery Cloth may be substituted for polishing or grinding. idk ex Three » Wood? Turning: Chisels,” Screw Driver, eight Drill Points---1/16 to 11/64 inch. LIST PRICES No. 1070 110V, complete $50.00 No. 2070 220V, complete $52.00 No. 3070... 32V,:complete $52.00 If your local dealer hasn’t one © of these in stock, write us. 7 7 . * e * Accessories 8 105

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106 POPULAR SCIENCE MONTHLY February, i9y There is no standing still... An Advertisement of the American Telephone and Telegraph Company Durinc the past two years 6000 switchboards have been reconstructed in the larger cities served by the Bell System to enable the opera- tors to give a more direct and faster service. Previously in towns where there were more than one central office, your operator would hold you on the line while she got the operator at the other central office on an auxiliary pair of wires. Now she connects directly with the other central office and repeats the number you want to the other operator. You hear her do this so that you can correct her if there is any mistake. This little change cost millions of dollars. Likewise, it saves millions of minutes a day for the public and it has cut down the number of errors by a third. It is one of the many improve- ments in methods and appliances which are constantly being intro- duced to give direct, high-speed telephone service. There is no standing still in the Bell System. Better and bet- ter telephone service at the lowest cost is the goal. Present improve- ments constantly going into effect are but the foundation for the greater service of the future. “Tue TELEPHONE Books ARE THE DiRECTORY OF THE NATION” A New Lightweight Electric Drill ort pena i preirt smrns 5 lore le. Grow The Vegetablesand Flowers ou would like to see grow- ng in your garden—read all about them in B *s Annual It describes Burpee Quale ity Seeds, Bulbs and Plants. A million people use it as their Leoemen guide. Writefor yourANNUAL today. It’s Iree. W. Atlee Burpee Co. Burpee Buildings, Box35l, Philadelphia Burpee’s Whittling Propelled 9 (Continued from page 105) stretch a thread from the rear hook the “cans” or motor guides to the bearing at the front. If the thread clears the stick at a sufficient height to allow strands of rubber to unwind freely, and if it passes directly through the center of the cang and the front thrust bearing, I know .there is little chance for motor trouble to develop. A new kind of prop that would offer poss. bilities for the experimenter would be one with a flexible blade portion near the hub to alloy an expanding pitch (Fig. 10). A little known fact about A-frame type mod. els with twin propellers is that the propellers do not have to clear each other. I have flown models with the props overlapping a full half inch. Traveling at the same rate of speed as they do, they seldom crack or touch each other, While many model makers depend upon a candle for supplying the heat to bend bamboo, a special bender can be made from a few of wood, a piece of fairly heavy sheet brass, and several nails as shown in Fig. 11. A spirit of some sort is also needed. One can be from a common sewing machine squirt can equipped with a wick. The brass gets hot in an instant and the bamboo can be bent without the danger of charring it or burning your fingers. Before any bending is done you must have a full size drawing for the wing tips, rudder outlines, and the like. Select a piece of bamboo a few inches longer than necessary and wide enough to make several of the frames under construction. Before doing any bending, turn the bamboo shiny side down on a flat surface and with a knife or razor blade scrape away the soft side until the piece is of the exact thickness desired. Be sure that this thick- ness is as uniform (Continued on page 107) PROPELLER HUB CUTAWAY PORTION SHAFT yi WASHER SILK THREAD WRAP RUBBER HOOK * FIG.8 T BEARING MADE SHAE ROM A COTTER PIN ee SHAFT BALANCE SHAFT _AFTER BEING STRAIGHTEN PROPELLER HUB FIG.12 Methods of making shafts and bearings; a bender HANDLE for bamboo; and a shaft balancing device. ris} This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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Ary, 1999 ick- “Ss pebroary, 1979 POPULAR SCIENCE MONTHLY 107 tll Whittling Propellers (Continued from page 106) ‘ble throughout; accuracy is essential. ide it gently with slight pressure over am ed com You will be able to feel it “» when it is warm enough to be pliable. Cnetimes the bamboo will become black on the underside, but if you keep the actual flame from touching it, there is no danger of its burn- ing. After bending to shape, hold the bam- hoo and blow on it to cool it; then it will retain the contour. HERE are several methods of splitting it. Tacha the best is to split it down the ex- act center and then split the half pieces down ‘s exact centers, continuing until the pieces are reduced to the correct sizes. A wire propeller balancer made as shown in fig. 1 is used to straighten a crooked propeller daft. Place the propeller shaft in the two loops and revolve it. You will be able to de- tect the slightest bend or irregularity. Remember that a large amount of undis- turbed air passing over a fin or elevator gives the most stability. For that reason a high fin ora wide elevator is to be preferred. An interesting point in connection with the tiny indoor model described by Bunch and Koch in the November, 1928, issue of PopuLar Sqence MonTHty is that it can be flown also asa “pusher.”’ Turn it around with the rud- der to the front, set the wing ahead so that the model will climb, and wind the propeller back- yard. By putting a left-hand prop on it, the model can qualify for a regular indoor pusher. With an almost identical model William Chaffee added thirteen seconds to the world’s record a few years ago. Choosing a Paint Sprayer (Continued from page 100) class, although there are variations between individual guns. The third type using small motors is that in which a gun attachment fitson the blower of a regular household vacuum deaner. This is a low-pressure gun. As all the motor-driven guns furnish a steady supply of air, an excellent class of work is possible with them. They are convenient and reliable. The next larger type of gun uses a siphon feed as a rule, but has a one quarter or one half horsepower electric motor with a small air compressor as a separate unit. Because of its greater air supply, such a gun naturally has a greater capacity than the kind just men- tioned. It is designed for automobile and fur- titure finishing and is practical also for inte- tior wood trim and walls of homes. For painting houses and barns, finishing automobiles and furniture, and for large sur- faces generally, spray gun outfits such as G areused by professionals. The outfit of this kind thown at the bottom of page 100 has a one- horsepower electric motor and a compressor which delivers seven cubic feet of air a minute atany pressure up to more than 100 Ibs. In ordinary operation it is regulated to use about twenty Ibs. pressure on the paint supply tank and from thirty to sixty Ibs. pressure on the gun to atomize the paint. There are air and paint storage tanks of large capacity, together with air regulating valves and a water and oil separating device, to keep the air stream clean. Either a siphon type of gun or a pressure-feed gun is used with this outfit. Mr. Vanderwalker, whose books on eeuns, the use of spray guns, and the e are regarded as standard reference works in the painting trade, will tell how to operate hand and foot pump sprayers and motor-driven spray guns in an article scheduled for early pub- lication. He will explain for beginners how various surfaces should be finished. * old the bamboo in your fingers, shiny side | basi sli cei a. at ad ATKINS “400”; finest saw made. Blade is “Silver Steel,” = point. Perfection e. Junior Mechanic; handiest, high grade saw for boys, or light work. 20-in. blade. Soy TARE cee ae ba ‘ eee Z — : Nickeled steel, adjustable Hack Saw frame. Non-breakable or ‘Silver Steel” Blade. po — * se abo e | | Se Mia Thin-Rim Mill Saws with cut-off or rip teeth. i | j } 4 ATKINS Groover or Dado Heads, in eight sizes. no aac This planer knife is only one of hundreds of Machine — it make of “Silver tee! Nag SILVER STEEL AW. For YOUR Home, Shop or Factory No matter where you cut wood or metal, ATKINS ‘‘Silver Steel’’ SAWS will help you do the work faster, easier and better. In your home workshop, ATKINS Saws and Tools add to your pleasure and profits, in making things and doing repairs. In the shop, mill or factory, ATKINS Saws and Tools make sub- stantial savings of time, material and money, in cutting and working wood or metal. In buying saws or tools remember the name ATKINS means longer service and more value for your money. The ATKINS products you want should be at your hardware dealer’s or mill supply house. If not, write us and we wil tell you where to get them quickly. Books on Saws, FREE \ Write for ‘SAW SENSE” X and ‘‘SAWS in the HOME,” \% or free booklets on whatever \% ATKINS Saws or Tools you re- quire, Use coupon below, wail a E. C. ATKINS & CO. £«. 1857 @ | 428 So. Illinois St., Indianapolis, U.S. A. Leading Manufacturers of Highest Grade Saws for Every Use; Saw Tools, Saw Specsalties, Plastering Trowels, Machine Knives, Grinding Wheels ond Files, Please send me “SAW SENSE”’ and “SAWS in the HOME,”’ or full information on (state kind of saws or om ee Cee es ee eh a | ee ae tense tease eee i BONIS. «o's 0.0 000 ctvule sash» demsaaaen pana | FFT OE Oe . My Dike Be... coe. snk CEA ! ca eens me came ame cms a come cams am toms we cae es ce ee os ed © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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POPULAR SCIENCE MONTHLY > ‘BLACK & DECKER Quarter-Inch Light Duty Electric Drill An unprecedented price for an electric drill of Black & Decker quality A strong, serviceable, Che Black &# Decker Mfg. Co. ff “With the Pistol Grip and Trigger Swi February, 15 THE BLACK €&? DECKER MFG. CO., TOWSON, MARYLAND, U. S. A. NAME I am interested in your new Quarter-Inch Electric Drill at $25. and will be glad to have you give me the names of Dealers in my vicinity from whom this Drill may be obtained. ADDRESS, page four of this issue A definite program for getting ahead financially will be found on Pa., > where $1.00.) Town and State Bennett Homes, 1029 Main St., North Tonawanda, N. Y. Send me your book of “Better Built” homes gad grepuee. (FREE only in Ohio, N.J., N. ¥., and New England; else- FEO. GRE Dhow n ccccccescconcmesccecseces I am interested in saving money on & house... garage... summer cottage... Remomememamems © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. a nn Home Workshop hemistry and Money [ive man who varnishes a piece of furniture or some apparatus whic he has just made, or the woman touches up a chair, is apt to discoye certain pertinent facts about varnishy from annoying experience. Some brands dry too quickly for gey. eral use and fail to form a smooth surface Others require several days for drying making it impossible for the amateur tp produce a clean job without a dust-progf room. Still others dry to a dull, unattras. tive film or else produce a brittle on which chips easily. However, the standard Government tests on varnish, most of which the amg. teur can easily perform, furnish a means of determining accurately the appearance, drying time, and elasticity of the film; and there are special tests for varnishes designed for special purposes. By pu. chasing only a small sample, or borroy. ing a few ounces from a neighbor, one can test any brand and often prevent considerable waste in time and money, These tests follow. Cut a panel about 3 by 5 in. froma clean sheet of tin of a grade weighing about half a pound to the square foot, This is rather light sheet and is specified because it gives a thickness which is ideal for the elasticity test. Hold the pane vertically by one corner, pour a portion of the sample over one side, and allow the excess to drain off. Place the flowed panel in a nearly vertical position ina well-ventilated room, away from the direct rays of the sun, and leave for four hours. At the end of this interval give the so-called “setting to touch test” by lightly touching the film not less than one inch from the edge. The varnish can be considered as passing this test if none of it adheres to the fingers, although it may still be soft. This means that the film is in no more danger of catching lint and dust. € Priest mg hours from the time when the varnish was first flowed on, test again by using a firm pre+ sure of the thumb and finger. If the finger does not move the film and leaves no mark which remains noticeable after the spot is lightly polished, the varnish passes the “drying fest.” Observe the panel carefully in a good light. The film should be smooth, glossy, and free from runs, sags, pits, and other defects. Leave the panel for another twenty- four hours. At the end of this time, test for elasticity and toughness by placing the tin in water at a temperature of from 70 to 75 degrees (Fahrenheit) for a few}f minutes; and then, with the film outw bend it rapidly over a \-in. rod until the panel has been bent double. Examine |} the film in a good light. A satisfactory} varnish, judged (Continued on page 109)

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Piece of IS which sy pur. ITOW- Or, one prevent money, from a eighing € foot. ecified is ideal panel portion 1 allow flowed n ina or four al give st” by s than varnish hough vat the ng lint venty- 2, test ' from a few i the ctory e109) February, 1929 a Home Workshop Chemistry (Continued from page 108) by United States Government standards, will show no cracking or flaking. These general tests can be supple- mented by several valuable tests for yarnishes designed for special purposes. For example, the cold and hot water tests which have been made familiar to the general public in advertisements. Pour a little of the varnish to be tested on two tin panels and let them dry for forty-eight hours, as described above. Then dip one of the panels into a bowl containing 244 in. of pure water at room temperature, immersing the end which was uppermost during the drying. Leave for eighteen hours. Ice water is not necessary and, indeed, is not ordi- narily used for this test. Remove the panel and dry at room temperature for two hours. The panel must show no whitening and no more than a slight dulling. In the same way, immerse the end of the other panel in 2% in. of pure boiling water and leave for fifteen min- utes. Then remove and dry for two hours. This panel also should show no whitening and no more. than a slight dulling. N OLD-FASHIONED Navy test for spar varnish, called the “safety of working test,” should be of interest to amateur boat builders and other users of exterior varnish. This is designed to determine whether a film will stand a stiff breeze while still wet. Flow a standard tin panel and im- mediately place it in the direct draft of a small electric fan (8 or 10 in. across the blades) running at full speed. The panel should be in a nearly but not quite ver- tical position, approximately 2 ft. from the center of the fan, and set sideways at an angle of 45 degrees to the line of the air current. Leave it in this position for five hours. Then set it aside and allow the varnish to harden overnight under ordinary conditions. The varnish should give a smooth film and appear free from dulling, crow’s footing, or frosting. Probably more floor varnish is used than any other kind, so one of the great- est needs of the amateur brush-wielder is to find a good varnish of this type. Build a large wooden panel with one side carefully planed and sandpapered and place it just inside the garage or workshop door. It should be of such a size that any one entering must neces- sarily step upon it. Now mark it into approximately 6-in. strips, each parallel to the door sill. Next borrow or beg from the neighbors as many samples of different kinds of floor varnish as you can find and paint a different strip from each can. The length of the panel will depend on the number of brands to be tested. ‘| Keep a record of the brands by number and leave the panel in the doorway for at least a month. Then clean the surface carefully and observe how the different brands have stood the wear and tear of shoe leather. Sometimes this practical and simple test will yield surprising results.—W. H. Hammonp. POPULAR SCIENCE MONTHLY FREE: A week’s better shaves. Just mail the coupon below. Ly cht hh hth O_o ho Can you get by with one shave a day? Or do you feel at five that you really ought to shave again? LONGER-LASTING SHAVE—because it’s a closer, smoother shave—is possible. We willingly prove it. Colgate chemists have achieved a unique lather. Differ- ent because of small bubbles. A scientific way to intensify the moisture content of lather. A principle which pre- pares the beard for closer, cleaner shaving. Hence a longer-lasting feeling of being well-groomed. COLGATE LATHER Colgate’s lather (greatly magnified) showing moisture contact with beard and minimum air. A common-sense prin- ciple scientifically authenticated and proved out practical- ly by millions of men. Two vital facts—easily proved Millions of men prefer Colgate’s because they’ve found—as you will—that as soon as you lather up with Colgate’s small-bubble lather, two things hap- pen: 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. Ordinary big-bubble lathers have more air, less moisture. A comparison will prove Colgate su- periority. Note our coupon offer of a week’s free trial. We will send also, a sample of After Shave, a new lotion—refreshing, delightful—the perfect shave finale. ORDINARY LATHER Ordinary, big-bubble lather (greatly mag- nified). Note air- bubbles which can’tsoften thebeard efficiently. Only water can do the job. Only small bubbles permit sufficient water, **After Shave.” Name COLGATE, Dept. B-1765,595 Fifth Avenue, New York Please send me, FREE, the seven-day trial tube of Colgate’s Rapid Shave Cream; also a sample bottle of

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--that mahe a BETTER VISE LIAMS’ new “VUL- CAN SUPERIOR” is the ONLY Chain Pipe Vise that provides these valuable features— 1. Overhead Adjustment — the handle is ON TOP where it’s easy to operate. 2. Reversible Jaws — for longer life. When the teeth first in use wear, simply unscrew the bolts and turn the jaws over. 3. Larger Capacity — each takes pipe 1/2” larger than other ein pipe vises of similar size. 4. Chrome-plated finish. Wholly made of wrought steel; no castings are toler- ated. Unbreakable —Com- pact— Rapid action —Posi- tive grip— Fully guaranteed. You need this unique tool in your work. If your dealer can’t supply you, write us. 2 SIZES: No. 11, for % to24"pipe No. 12, for 4 to44"pipe J. H. WILLIAMS & CO., “The Drop-Forging People’”’ 246 Vulcan St., Buffalo, N.Y. WILLIAM VULCAN SUPERIOR CHAIN PIPE VISE POPULAR SCIENCE MONTHLY Upholstering Old Chairs (Continued from page 102) A good layer ‘of sheet cotton must be spread over the cloth which covers the filling, and all irregularities filled out with cotton. Then the upholstering material is stretched over this and tacked underneath. All upholstering over springs is done in a similar manner. In many cases the bar and spring method is replaced by webbing and springs, the webbing being tacked to the under- side of the framework, as shown in Fig. 5. Coil springs are sewn to the crosses, then tied as before. The bar and spring method is more durable and should be used when possible. In many old pieces where the wood has been badly weakened by tack holes, the webbing is replaced by bars and springs. As each bar is suspended from the top of the frame, it is not likely to give way. Springs should be used with webbing only where the seat frame is of the apron type and forms a box in which to set the springs. At the left of Fig. 5 is illustrated the flat type of seat, in which burlap should be tacked directly over the webbing, then the seat filling applied, and the upholstering completed as described. At the right of Fig. 5 is shown another and more economical, only not quite so comfort- able, a way of renewing worn-out seats. In this instance a board of suitable size and thick- ness is nailed or screwed to the underside of the Fig. 5. Whether webbing or a thin board is used to make a foundation for upholstery on a flat seat frame, it is applied on the underside. seat, then filled and upholstered as just sug- gested. The dotted line shows the edges of the board. Figure 5 represents excellent ways of renew- ing cane, splint, or rush seats. Anyone can make this type of upholstered seat, but it is almost impossible to find a man who can or will renew the seats as they originally were. Any of the materials whose use is recom- mended here may be obtained from uphol- sterers and repair men, as, ordinarily, they carry them in stock. Pieces of upholstery materials may also be found at the same places. Many upholsterers stock a goodly supply of samples and remnants of tapestry, velvets, velours, mohairs, plushes, imitation leather, and other materials. These are kept for sale and may be had for from one twentieth to one quarter of the regular price a yard. There is one kind of upholstering which no one should ever try to duplicate; and when a piece which has this kind of upholstery on it is gone over, it should be changed to plain filling. The kind I refer to is called “biscuit tufting”’; it consists of wads of tow or other filling with the covering drawn down between the wads with buttons. This method not only catches dirt and dust, but it holds all it catches. Upholstering, as such, is actually a trade in itself; for those who have had no experience at all, a visit to some repair shop might prove of value. Repair men asa rule are genial fellows. They are usually willing to show others how to do anything they can do themselves. I have found it a pleasure to show a number of persons all I knew about different jobs they wanted to do themselves. This is the eighth in Mr. Stanley’s series of articles on restoring old fur- niture. The next will be published in an early issue. f Under-Producer Stands Up for the HIGH | Noodo- OO Tinconroraren HARTFORD, CONN. Peon ens Producer— Need ROOT 2D Dyes iy = HEAVY DUTY Bizsx PRESS COUNTER This new Press Counter will keep watch of the workman who’s apt to lag and let his production sag. It will keep his record in front of him, and keep his mind on his task. It will make him responsible for a better showing. Subject to check-up at any minute. Your industrious worker will show his speed as never before, when it registers on a Counter. It will prove his value, protect his job. He’ll be sure he’s paid for all he earns. You'll be sure you get all you pay for. har ere Vs Just alittle more work from ma- chines, a few more pieces per minute, fewer over- or under- runs will promptly pay for these Heavy Duty Press Counters at $6.50 each (Subject to{discount on quantities) Ask for special circular with full particulars about Press Counters. Small-Counters This small Rotary Ratchet Counter (No.6) counts reciprocating move- ments of the lever, as required for recording the output or opera- tions of small machines. When m= the lever is - moved through j an angle of 40 to 60 degrees, the counter reg- isters one. The farther the lever is moved, the higher the num- ber registered. A complete revolution of the lever registers ten. This counter can be adapted to no end of counting purposes, by regulating the throw of the lever. Price'$2.00. (Cut nearly full size.) Small Revolution Counter, also $2.00. Our brown book shows in- struments’ that ‘count everything on earth.” See them—by sending for the book. icant = & This seal on an advertisement in POPULAR SCIE.:JCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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—O Or = tw 8 pebcosey, 1929 ——— Ping-Pong Table (Continued from page 77 Fig. 3. Hand screws are used to clamp the reinforcing pieces to each section of the top. the end pieces of the two sections which are to receive within their recesses the square ends of the disassembled side rails, place 34-in. dowels as indicated in Fig. 2, underside view. The dowels are to hold the rails in place while the board is doing duty as a screen. Cut crosspieces to fit between the long sides of each section. Those for the two middle sec- tions should be cut down to 3¢ in. in thickness for 10 in. from one end to allow the side rails to be fitted there, as in Fig. 2. Fasten all joints (except at the cut-down ends just men- tioned) with 14-in. corrugated fasteners. Plane the edges of each section. Bevel them a very little toward the underside to insure perfect contact between the sections on the playing surface of the board. In order to make adjoining sections flush at the joint, place five 2 in. wide brass or steel butts on the back of the two outside joints— that is, the joints between leaves one and two and between three and four. To place these, lay two joining sections face down on a flat surface and hold them in perfect contact while all the screws are driven home. Turn the pairs of sections right side up, bring them together for the middle joint, hold them in perfect contact, and put five hinges in place on the top of the board. The plates of these hinges may be set in flush if desired, but they will come under the net out of the way of the game. Place rubber domes—rubber tipped nails—to protect both the ends of the sections and the floor when the board is used as a screen. All parts of the board itself are now in place. To finish the table complete in itself, pre- pare four legs of the dimensions given, pref- erably of oak or other hardwood. Place them 8 in. from the ends of the top and fasten them with 3 in. wide steel or brass hinges, as in Figs. 2and 4. See that the entire barrel or round part on the hinge is on the leg. Use 1-in. screws. Obtain eight hooks at least 17 in. long and sixteen heavy screw eyes, say of 3¢-in. wire or No. 5 American wire gage. Attach four of the hooks with the screw eyes to the inner faces of the legs as shown in the end view of Fig. 2. Raise the legs until they stand perpendicularly, then locate and place the four eyes in the underside of the (Continued on page 112) Fig. 4. Mr. King demonstrates how the legs are hinged to the reinforcing strips of the top. POPULAR SCIENCE MONTHLY yin Compared to It’! HAT’S how a New York rid- er compares his Harley-David- son to an airplane. And he’s right! “Twenty horsepower on two wheels — that’s real sport”, he writes. \. There’s nothing like it — the sheer joy of lively power, silent speed, and rushing getaway that the Har- ley-Davidson rider revels in. Just ride one of the 1929 models and see! The Harley-Davidson in the picture is the new “45” Twin— the won- der motorcycle that sells at only $290, f. o. b. factory. Look it over at your dealer’s today. And mail the Coupon for illustrated literature. HARLEY-DAVIDSON HARLEY-DAVIDSON MOTOR CO., Dept. P.S, Milwaukee, Wis. Interested in the [1] “*45°° Twin, 1) Big Twin, 0 Single. Send literature. Name

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a Se cutting edge | Jom want hack saw blades taren’t afraid to tackle the toughest metal, that keep a biting edge throughout an unusually long service life —specify Simonds. he reason for the long- wearing qualities in Simonds Hack . Blades ies = the special heat-treat ung- sten steel from which they are made. This steel has been developed exclusively by Simonds in Simonds plants. No other steel can add so much toughness to cutting tools—so much wear-resis- tance, so much dependable — . ‘ t pays to keep a supply of Simonds Hack Saw Blades on hand at all times. They form an important part of every well-equipped work- shop. The keenest judge of coal quality—theexperienced craftsman who knows the finest cutting tools—will tell you that for real economy | and satisfaction it pays to use Simonds. Ask your dealer. SAWS FILES KNIVES STEEL SIMONDS SAW AND STEEL COMPANY “The Saw Makers” Established 1832 Fitchburg, Mass. BRANCH OFFICES AND SERVICE SHOPS IN PRINCIPAL CITIES ———— POPULAR SCIENCE MONTHLY Ping-Pong Table (Continued from page 111) ~ as shown in the same view. Ignore the ot er four hooks for the time being. Get out four rails % by 434 by 55)4 in. long. These are made 4 in. wider than the corresponding notch (marked A, Fig. 2) of the legs to which they are related; the extra width is to allow for the space left by the hinges of the legs. Slight planing in width, however, may be required. Make the splice joints as shown in Fig. 5. Verify all dimensions before making these joints to insure that the ends of the rails will be flush with the outside of the legs. Prepare four cleats 34 by 144. by 4%4 in. and fasten them to the rails as shown in Fig. 5 with glue RAIL AND LEG UTSiDE vd EW SEPARATED S bef PA LS Y/-stORAGE YW 1 7 DOWEL PINS SPRING BRASS CLEATS Fig. 5. Details of the legs and rails: how they are held in place with springs when folded. and 1%-in. No. 10 screws. Put the rails in place by making accurate cuts to suit the legs and joints. There should be perfect contact between the rails and the underside of the = top throughout the entire length of the rails. Bore 5¢-in. holes.through each spliced joint as at B, Fig. 5, to receive 14-by-5-in. carriage bolts. The heads of the bolts must be sunk into the top edge of the rails. Also bore holes through both rails and legs as shown to receive \4-by-214-in. bolts. . Now fit the remaining four screw eyes to the legs and drive the corresponding screw eyes in the under edges of the rails as in the side view of Fig. 2. Bore holes in the end of each rail to drop over the dowels which help to hold them in place when the table is folded. Fit pg to hold the legs and the rails after uing and bradding small pieces of wood to the underside of the top where necessary to receive the springs. Cut notches across the middle pieces of the end sections to receive the hooks and place springs to hold them there. If the outside sections are ever folded far back, it may be necessary to cut the cross- pieces of the middle sections away at C to receive the springs. bruise the wood at D, cut away the wood neatly. A cloth pocket to receive the bolts may be tacked and glued in place as shown in Fig. 2. Should the leg hinges Get out two net posts 4 by 244 by 12/4 in. and place two screw eyes in each to receive the net strings. Fit each post over the edge of the table and (Continued on page 118) D DAYS Tri; WAITES with ink free and cam g w, 2 lead pencil without s a pA skip or blur. Won't blot, sac, leak or soil hands. Patented aug C. R. Morely, Allentown, Pe.) You don’t have to prime it or pet it to get it started. Works great —W-H. m, Tampa, Fla. 3} nism t order. Have improved 50% in fa i bnew | ’ © get out of ¢ using your eg an Makes 3 Cari, Weore 18 to 22 letters and addi ~ oa With that many enve ot riginal In h ling. > wrnne ia L. Connelly, Brannon, IIL “Sess ‘ nk Writes smoothly, like point was greased. \ Bear down as hard as pw what kind of paper.’ like, without fear of ‘ine upping tags. _ = ¢ i —E - Sunms, Jersey City, N. }- ee ing ina 4 fm tickled skinny. It's a darling, can make 6 its 14 ke carbon copies of ts and send original in gold point. Ideal for ink to factory instead of penciled sheet. © men’s Orders, Privang —A. Watson, Elgin, uh) , My Inkograph is simply’ s ee, —— “> CY Ke =. a ¥ P : other. — iss 1 n Ward. eel T Say \\ Of any Laramie, Wyomi ie rt A ‘requiring ‘ cf — clear carbon copies, ’ That Hard A P E N oF Lik kt. Gold Point REFINEMENT CATALOG Made of finest highly polished, fountain pen material, with 14kt. solid gold point and feed, safety cap, self-filling lever and clip. In workmanship, quality and it is the equal of pens selling for a great deal more. Also made m small size with ring on cap for men’s watch chain or ladies’ sautoir. SEND NO MONEY "21727 2csrens sent prepaid if remittance accom panies order. Year's guarantee certificate assures_absolute satisfaction Your money back if not satisfied within 10 days, INKOGRAPHICO., inc. *°°,25: fonts Send for inkograph or write for gle AG ay hy plan booklet. Big value,—sells on sige 7 —no =p ; * immediate commissions. © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. Skin Troubles CLEARED UP—OFTEN IN 24 HOURS Pimples, Blackheads, Acne Eruptions a the Face or Body, Barbers Itch, Eczema; Enlarged Pores, Oily or Shiny Skim *‘Clear-Tone’’ has been tried and testedii over 300,000 cases. Used like toilet water, Is simply magical in prompt results, At All Druggists—with Proven Directions Ask Your Druggist— You Can Rely on Clear-Tone [ TRACE MARK AEG. MARK REC. FOR SKIN AND COMPLEXION FLy THIS ARMY PuRsvuIT SHI?! Light and fast, this one-foot model is a insignia on wings, in colors. Construc- tion set includes ready-made aluminum propeller, shaft, band motor, stream-line wood wheels, pre-cut balsa ribs # other parts, with clear di i Can be bled in 3 brs. Javerage 14-yr. ol » without tools. Complete set, packed in a breakable mailing tube, only 45, Ros id in U, 8S. d or } money order today (no stamps). int address plainly. Satisfactioy or money refunded. LOGAN TOY WORKS, 35 E. Gay Street, COLUMBUS, 0. (We cannot make C.O.D. shipments. No retail catalogue é How to Work with Tools and Wood This book explains in a simple, straightforward manner all the processes of working with tools and wood. It takes sll t# mystery out of using tools and enables you to spend interesting and profitable hours in your home workshop. details are clearly explained, Price $1.00 POPULAR SCIENCE MONTHLY 250 Fourth Avenue New Yorke City

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February, 1929 Turning Oversize Work (Continued from page 96) will often be all that is necessary. As has been shown, the bore will be concentric, though ing, so that the reamed hole will be in . The right reamer is not always available, owever; besides, it cannot always be applied. ore it will pay to remember that by having the tool very nearly central in taking ‘the finishing cuts, we will be able to produce turn or bore which will be very nearly right, in spite of the sag in the axis. The table at C in Fig. 2 will give an idea of | how near the center it is necessary to set the int—or the center of the grinder spindle— | to get accurate results. Usually the best way ‘will be to set the tool as near dead center— true theoretical spindlé center—as possible; OR TURN CAUSED BY SAG OF ND. OF WORK IS” FRONT When work is so heavy it sags, set the tool as nearly central as possible for the finishing cuts. for, although the entire axis of the work is below this line, the rotation of the work has a tendency to throw the point of the tool down and thus even up matters. Every effort should also be made to prevent sag in the spindle. Sometimes the situation can be bettered considerably by mounting the work on the faceplate instead of holding it in the chuck, as may be seen from Fig. 3. The heavy four-jaw chuck at A sets the work out much farther from the spindle bearing and adds, besides, a heavy weight of its own just where it is not wanted. By substituting the faceplate as at B, the weight and its effective leverage on the spindle may be reduced to half and less in many cases. Not only will the likelihood of error be lessened in this manner, but the spindle will often be saved from undue strain. In some other cases, the steady-rest may be called in to help. Where the work is not otherwise of a shape that will offer a hold, a “stub” or extension may sometimes be cast on for this purpose and turned off as a last operation. Merely supporting the work in this manner, however, (Continued on page 114) How sagging sometimes can be reduced by sub- stituting a faceplate for a heavy four-jaw chuck. — 4 canal ann: t IE At La = {tk 8 ~~ NO APPRECIABLE ii SAG |! ? FIG. 3 POPULAR SCIENCE MONTHLY 113 ORTURED by constant pressure, your brakes—or rather brake linings —tend to become “metalled over” —and when this happens, they squeal. Service men stop this squealing by using a 10” Flat Bastard File to remove the “metalled over” spots from the brake linings. Other files that will prove useful on your automobiles are the Nicholson Tungsten Point for cleaning electrical contacts, and the Nich- olson Half Round Bastard File for getting into places where a Mill or Flat File would not fit. At your hardware dealer’s. NICHOLSON FILE COMPANY Providence, R.1., U.S.A. “A FILE FOR EVERY PURPOSE ” © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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114 POPULAR SCIENCE MONTHLY February, 1929 and YOU eee That’s why we made this good wrench for you We have spent a hundred years and a lot of money perfecting this wrench. That is why most experienced tool users specify the B & C Adjustable S. They'll shop around a bit, of course—all of us like a bargain— but thousands on thousands ‘of people —like yourself— have planked down their good money 125 Main St. Poor Tools .S for this fine wrench. In the long run they had a real bargain. In self-respect alone, it was worth a few soon forgotten pennies. You just seem to do better work —and enjoy it more—when you think, as you pick up your B & C Adjustable, “There isn’t a bet- ter wrench made.” Sold by leading hardware dealers. Used by men who love good tools. BEMIS & CALL COMPANY Springfield, Massachusetts Ny OF ‘*Lava-clean” it. “Good old Lava,” they call it. Gets hands clean! Not just “surface clean,” but clean ’way down deep. As easy on your hands as fur-lined gloves—because it’s made from the finest of vegetable oils. All grocers and druggists sell it. Full size cake of Lava Soap FREE! «--—-=-== Mail this coupon------~ - Procter & Gamble (Dept. X 229) Cincinnati, Ohio. ' send me, FREE, a full size cake of Please LAVA, the hand soap that removes all the dirt and grease. Teiid Your Scale Model Airplane the IDEAL way! many realistic other models. are controllable b and rudder. Also Models of FOKKER, DeHAVILLAND and other aircraft or send for our big Catalog IDEAL AEROPLANE & SUPPLY CO., Inc., Headquarters for 18 Yearsf 28 West 19th Street, New York City [PEAL Models are accurate, scale-reduction copies of famous Airplanes; perfect duplicates in appearance and construction details, with arts and fittings not found on hey make long, perfect hts and movable ailerons, elevators Build an IDEAL Model—it’s the easieet, Srekess and latest wa AY construct a si re ie correctly. “NSPIRIT of ST. LOUIS” shown above. 3-ft. Model. Complete Construction Outfit. . . $7.50 , CURTISS Ask your Dealer for IDEAL Model Airplanes, Plans for Model Airp sane sin Cone ay mes poral ge $ Fy r Wopoplaneet Geel P = 25 cents each. Catalog Free . 64-page Catalog - Sc apne ig ate Aviation information. Send for yours now! —___e Turning Oversize Work (Continued from page 113) FIG. 4 When you suspect a piece is sagging, run an indicator along either the top or the bottom. does not do away with the disalignment. Since the spindle sags the moment the work is in place and it is usually difficult to determine the exact amount of sag, there should be some means that will automatically bring the spindle back to alignment. Figure 1 shows a simple way to solve this problem. The supporting end a is first turned to the proper diameter. The spindle is then stopped, a scantling b placed across the front vee and under the work, and the end weighted down so it will approximately counterbalance the weight of the work—and of the chuck, if one is used. The lever should take hold about under the center of the work, which in the present case is accomplished by nailing a small block on top of the scantling. Where the work is too large in diameter, the scantling may be placed below the bed and across a sawbuck A 2 NE AT ROTATION FIG_S Diagram to illustrate the bending moment in a lathe spindle caused by a very heavy casting. placed parallel to the lathe as at B, a long block a being used on the end of the lever to reach through the gap and support the work. With the work so balanced, the steady-rest can be adjusted, the indicator showing if the work sags on easing off the weight, or if it is pushed up while being adjusted. This is the third of a series of arti- work on lathes and other machine tools. The fourth article is scheduled for early publication. Mr. Simon is endeavoring to sum up in them the results of his own long experience as a toolmaker and machinist and as a designer of machine tools. He is one of the world’s foremost writers on machine shop problems. @ This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. cles on easier and better ways to hold | | the con cutting work te it is sit advant As v illustra fully di one ha ends 0 Every then c: The the wi size of $4 in. accom’ by thi a doze in a gi The holes : hole v

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ry, 1999 re = al ee 8 a! For=Bpesme &aRB BE: februarys 1929 isavers for Shop Men (Continued from page 94) be : tessa ond. The dimensions given in the cut are for yerage diamond, which will be about 3¢ e aneen, and, of course, can be changed to suit the size of diamond to be mounted. —Hector J. CHAMBERLAND. N USING parallels under flat work that has | to be milled or ground, considerable difficul- ty is often encountered either because the par- tip when the vise is tightened or because they are subsequently jarred loose under the action of the cutter or wheel. The result is only too often spoiled and damaged work. By spending a few odd minutes to make some rs in the shape of thin leaf springs like illustrated at the top of the third column on page 94, trouble from this source can be avoided. Several spreaders of different width and degree of curvature should be made to take care of work of varying width and height. By making the spreaders of spring brass or bronze, the danger of damage to a milling cutter which might come in contact with them is avoided. Though it is not necessary to use the “but- ton” shown in the drawing, it is advisable to have it where it is possible to provide the par- allels with a small hole through the center. An easy way to obtain the button is to cut a round- headed screw or rivet off just slightly below the head and rivet or solder it in place. A spreader of this kind is rarely if ever in the way and is almost always a great improvement over using unsupported parallels. The spread- ers will also be found useful where a special de- vice, such as a “‘spider,” is not at hand when lining up short work in the lathe chuck, and it js necessary to resort to parallels. — are various devices for gaging the points of drills. The writer previously con- tributed a gage that shows the concentricity of the point and derives its particular usefulness from the fact that the correct location of the point goes a long ways towards insuring the correctness of the cutting angle. On the prin- ciple that we usually think of the simplest thing last, the writer now offers a gage which, besides verifying the drill size, at once shows the concentricity of the point, the truth of the cutting angle, and the clearance. his truly universal gage is a little more work to make than other devices, but, even so, it is simplicity itself, and the combination of advantages it offers will recommend it. As will be seen from the lower right-hand illustration on page 94, a row of holes is care- fully drilled in line in a piece of flat stock; then one half of the stock is milled away over the ends of the holes to expose the cross section. Every element entering into the point design then can be checked at once. The gage can be made from 8 to 4 in. long, the width and thickness being controlled by the size of the drills. The particular gage shown is $4 in. long, 5% in. thick, and 114 in. wide, and accommodates drills from 14 to 134 in. inclusive by thirty-seconds. For small drills, as many as a dozen and a half sizes can be accommodated in a gage of similar length. The main things to watch are getting the holes all in line and straight, and finishing each hole with a drill freshly ground exactly to the right shape. While it is not necessary to have the gage hard, it will pay to make it of non- shrinking tool steel and heat treat it; this will also give it the desirable dark color. At A is shown a drill slightly off on one cut- ting lip. From the same view it will be plain how the clearance may be ascertained by turn- ing the drill slowly to the right. If the space between the lip surface and the edge A of the gage steadily increases as the drill is turned, the amount of clearance is plainly seen, as are also any spots on the lip surface that are too high or too low.—HeEnry SIMON. than is necessary. The completed holder | turned to fit the device in which it will | POPULAR SCIENCE MONTHLY Plymouth Built-in China Closet See LePage’s Book, page 6 12 NEW Job Plans, Too! There is, of course, a limit to what we can give in LePage’s New Third Home Work Shop Book for only a dime. But we realize many men want addi- tional projects. Hence our 12 new Job Plans. These also were made by Mr. Klenke. They are projects that require more elaborate presentation than we can give in our book. Each Job Plan presents one project on a single large sheet of paper. Each is well worth its price, one dime. Look over these projects and order those you want by number (see coupon), enclosing 10 cents for each. 16 Sheraton Writing Desk 17 Sheraton Desk Chair 18 Colonial Hanging Book Shelves 19 Smoking and Reading Cabinet 20 Colonial Mirror 21 Tea Wagon 22 Telephone Cabinet 23 Stool for Telephone Cabinet 24 Manual Training Work Bench 25 Home Worker's Tool Cabinet 26 Spanish Galleon 27 Vanity Table E GLUE HANDIEST TOOL IN YOUR WORK SHOP Cape Cod Chest AGE’S of Drawers See LePage’s Book, page 3 - _ Old Salem Ship’s Cupboard See LePage’s Famous Colonial Furniture You Can Make Yourself LEPAGE’S New Book Shows How To Reproduce These Beautiful Pieces at a Fraction of Store Prices ‘ook, page & LePage’s latest book, “ The Third Home Work Shop Book,” contains complete directions for making 20 at- tractive pieces of household furniture, 5 of which are reproductions of famous old Colonial pieces, including the 3 shown above and in addition, an Alexandria Nest of Tables and a Lady Washington Sewing Cabinet. This versatile book also gives you for the first time, di- rections for making 5 pieces of modernistic furniture, so popular today. These include Set-Back Book Shelves, Modernistic Desk, Modernistic Table, Modernistic Fold- ing Screen and a Modernistic Fire Screen, Expert Instruction Any man handy with tools can make any or all of these 20 pieces of furniture, for a fraction of their retail price, which a careful check in shops showed would be about $1000 for the 20. | : : _ You have expert instruction to guide you. The designs, dimension —— photographs, step-by-step direc- tions and the actual furniture itself were made by William W. Klenke, Instructor in Woodworking, Central Com- mercial and Manual Training High School, Newark, New Jersey. His experience as an expert gives assurance that each project and the directions for making it are thor- oughly practical. The other popular 10 pieces which this LePage’s Book shows you how to make, are: Chess and Checkers Table, Smoking Table, Caned Side Chair, China or Book Cabinet, Book Trough and Magazine Stand, Magazine Carrier, Vanity Case, Book Stand, Fernery Stand and Fold- ing Cowling Screen. Where else could you get complete directions for making all these for only 10 cents? Send 10c for this NEW LePage’s Home Work Shop Book Simply use the coupon below, sending it to us with 10 cents in coin or stamps, and we will at once send you a copy of this latest LePage’s Book, postage paid, MAIL THIS COUPON LePage’s Craft League 612 Essex Ave., Gloucester, Mass. Gentlemen: Enclosed please find 10 cents (coin or stamps) in payment for LePage’s New Third Home Work Shop Book. Please send a copy of this book to. NAM. cc ccc pccccccccccccesccececcccecceceeeeeeesesons Street... ccccccccccvcccccccccseccccscccccecsecsccccces BR ccccsccccescsccsecocosnsssens BUASO. ccccccescccsces Please also send the following Job Plans.......... indicate column at left), for each by number those you want. of which I enclose an additional 10 cents.

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116 POPULAR SCIENCE MONTHLY 7 7 : : a c \/ T > Turning Rings of Wood /\ | I) HW i Mh f i | (Continued from page 79) " yi } Lg edge. Alternate with a 1%4-in. skew chisel, f ; Ps P My es P| which should be held so that it cuts with the 4 toe (see Fig. 3, page 114, Oct., 1928, issue). Test the diameter of the hole with a pair of inside calipers. Then round the edges and sandpaper the work. The dead center should now be moved up again, so that its point bears against the wood at the bottom of the hole just cut. This added I ey support is needed for cutting the first napkin EP ict i. ring away — the parting ~~ The —— ~ ing one is then bored and cut off in the same oe A WORK KNIFE The remaining end of the 6-in. piece is now THe man or boy who wants a knife to do turned until it is equal to the diameter of the things with, will not find a better one than holes which have just been cut halfway | this, It belongs in the car, garage, tool ki through the two napkin rings. The length ou en, Wines fishir SAraBe, | te should be a little less than the depth of the : nl, " nif msde tee, Dali hole, so that the napkin -rings will butt up ing you'll want this knife. You'll need it work. against the square shoulder formed on the | ‘8 around the house, garden or farm. piece as in Fig. 2. The cutlery blades are sharp—hand-honed at the HILE turning this chuck, try the fit of factory. The fine, high-carbon steel will hold its both napkin rings frequently, because biting edge. The screw-driver is a practical tool the hole cut in one napkin ring is likely to be — made to fit average household screws, The slightly larger than the hole cut in the other. | can-opener works and doesn’t slip. The punch, Finish the larger one first and then cut down or reamer blade is solid-forged and can be easily the chuck to fit the smaller one. Do not force resharpened when necessary. The cork-screw pa too tightly on the chuck or they may is onto its job. split. Bore the other half of the hole in each ring Beautifully finished — reinforced brass linings, as explained above. Then stain and polish the nickel-silver bolsters and shield, stag handle, rings. . ‘ : When a ring having a circular cross section See one of these knives at y — dealer’s, or, ifhe is to be turned from a solid piece of wood, the hasn’t one in stock, send us his name and $4.00 stock, after being faced off, should have the for R3843. It will be mailed to you promptly, same thickness as the diameter of the cross section of the ring, as indicated in Fig. 4. A | REMINGTON ARMS COMPANY, Inc, piece of 14-in. plywood is placed between the Established 1816 screw chuck and the material to be turned and 25 Broadway New York City prevents the screw in the chuck from pene- \nir 7 trating the 34-in. disk. After facing off the disk and turning it to the required outside diameter—in this case 4 in.— it is cut down as shown in Fig. 4. The square corners are then cut off (Fig. 5), after which the ring is rounded as shown in Fig. 6. A template may be made of a piece of strong cardboard or veneer about 2 in. square. Pro- ceed as follows: Draw a straight pencil line p R about in the center of the piece of cardboard. ‘ Tack it to a piece of wood, place the screw of , 4 " an auger bit of the desired diameter—in this case 34 in.—on the center line, and bore a hole. Cut on the line with a knife, thus dividing the cardboard in two pieces. Use half of it as a ( Remington TRADE MARK © XG template (Fig. 7). / R-3843 (CCHuCE the partly turned ring as shown in = /, PRICE #4-00 Fig. 6. The wood used in making the chuck may be soft, and it ig well to have it thick in case the recess cut in it should be too 3 large; in that case it may be faced off again ke Gh) yj and another recess cut. The center is now cut N (6) away and the turning of the ring completed. —— s aeaeiienl Such rings may be used for the hanging of | © 19298. A. co. 2492 curtains or portieres, or as towel or necktie | = * Obviousl ! rings. A necktie holder is shown in Fig. 8. It evan e fits into another np =~ which is screwed | /» PR . to the wall or to a closet door. are desirable for Ma- meet ene'tasle..foc Sve work. For A small section is cut out of the ring, thus chininte cad Tockeatey operations that require skill and crafts- ven ay : ; ers. Save their cost by manship, choose tools that combine exact permitting it to be sprung a little and slipped ot Eno. Coe balance with the best of material—Pexto into a hole bored in each side of the turned free. Tools. Y il End them d Ratha and piece. The center of these holes is found by s long lived. Look for the Pexto trademark | Wapping a strip of paper 7 in. wide around tty when you buy—a mark of worthwhile the piece. Cut the ends of the paper so that Dayton, Ohio enols they just meet. Remove the paper and fold Popular Seate'te the Pesto Line include it once in the center. Draw a pencil line length- wise through the center of the paper, wrap it again around the wood, and prick a hole on the center line where the ends of the paper meet and another where the pencil line crosses the The Midget . *Five-in-One” Slide Rule GA is a combination Mannheim, Pol \ ric, sie. Binary, Add and PANY) an aleSpty and divide any com: . vide Chee Pema sot crees Braces, Bits, Pliers, Wrenches, Snips, Squares, Hammers, Chisels, Pruning Shears, Screw Drivers, Draw-knives and Calipers. ; - Is. Gives ven fold (Fig. 9). Bore these holes while the ph b+ --™ Send for Booklet “S turned piece is in the lathe and before the ends Y and f ing cr ieee THE PECK, STOW & WILCOX CO. | have been cut off. Bre nwtryctiode. $186. usntooy ___.. Southington, Conn., U. S. A. Peat eee it tee Se rs] This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. in : 7

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Fe. ao 5 Fr’ R eer rs dbbrieg 77

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EASY TERMS Our terms are all in your favor, a new and revolutionary method of purchase. Many pay for their Workace Shop out of the profits it makes...A 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— and we'll see that you get fall details and a complete descrip- tion by return mail: SEND TODAY J. D. Wallace & Compa ! Wilcox St. and California ‘Ave., { Chicago, Illinois. | That Workace Electric Woodworker sure looks good to me. | I want to know ALL about it, including your easy terms, right | away.

INCLUDES ALL THIS: 4” Planer 8” Circular Saw 6” x36” Lathe 8” Disc Sander 6” Buffing Wheel 5” Emery Grinder 14" Drill Chick 4, H. P. G. E. Motor, 110-Volt, A. C., 60 cycle Endless V. Belt, two 4” and one 2%” V Beit 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,

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source of income—send this coupon Sadi. |..:0<0i.'sss\ ie apsipgdadeae ean : for all details of this unusual prop- Workace 14” Bandsaw Heid ot Mantnees. «30265 ee eee j Ss ’ Re OT * f PMBIONBS on 0.0 6:0 9c 00s ep eurings ee CCRes es 1 t0e osition. Spesdy. acousses, 675 j Address...........sseeeceeeeessereneesenenereecee: j J City... 6. . cece ee cence eee e eens State:..|...... zi vavssvgden | Ee aie

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

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Hand-Forged SIV ARS *~\ GUARANTEED || _ against breakage ADE from a new alloy steel which resists fatigue and shock, goes through brick, rock or con- crete in quickest time without bind- ing. PLOMB Star Drills will not break in service, All last longer and Sizes Sold stand more by abuse than any aie other drills wg made. Every Plumbing mechanic and Auto- should have motive Jobhers. PLOMB a Star Drills tools for 20 They as- years for the Auto Mechanic, sure a Plumber, Stea: i Fitter, aioe — and other Artisans, job. Every PLOMB hand-forged tool is fully guaranteed. See Display Board at your Dealers. © Plomb Tool Co. 2209 Santa Fe Ave. Los Angeles Send. Se This hand-forged key-ring screw driver, sent for 12¢ in stamps o7 BLOMB qualit, Name OPP eer RE bbahinitnestenescacsecosserceses cesecooeee Write Name ‘of Dealer in margin PLUMBING GARAGE HARDWARE Pome ecnfer: [) UO POPULAR SCIENCE MONTHLY Turning Rings of Wood (Continued from page 116) should be a little larger. It may be flattened slightly on one side and fastened at right angles to a wall or a door with a round-head screw (Fig. 10). These rings may be made stronger and more interesting if they are made of three or more layers of wood, preferably of contrasting colors, such as walnut and birch. Thin layers of ebonized wood about } in. thick will appear as black inlaid lines. The layers should always be an uneven number. If three are used, the inside layer should run at right angles to the two outside layers (see the section in Fig. 10). It is obvious that the layers should be glued up into a solid block or disk before the ring is turned. (THE turned picture or mirror frame is simply another type of ring. Make a full size drawing of the frame and screw a piece of wood of the required dimensions to a small faceplate. Face off and turn the piece to the desired diam- eter. Cut the recess for the picture, glass, and backing as shown in Fig. 11. If the frame is going to be thinner than the one shown, it will be necessary to back it up with a piece of ply- wood as shown in Fig. 4 to prevent cutting into the screws. Remove the disk from the faceplate and turn a chuck as shown in Fig. 12. The disk is now fitted to the chuck, its center cut away, and the design of the molding turned. Some wood turners prefer first to turn and polish the face of the frame, then to chuck it, and finally to cut the recess for the glass. The method described above permits the molding to be finished and polished after all the cutting has been done and prevents it from being marred by chucking. Other designs for picture frame moldings are shown in an article by Mr. Klenke on page 82, December, 1928, issue. Books on wood turning having many attractive designs may also be consulted in most public libraries. The following are to be recommended: Course in Wood Turning, Milton and Wohlers; Art and Education in Wood-Turning, William W. Klenke; Wood Turning, George A. Ross. To obtain the best results, a close grained wood such as birch, maple, mahogany, or wal- nut should be used for projects of the kind de- scribed in this article. Directions for finishing turned articles were given on pages 132 and 133 of the October, 1928, issue. Mr. Hjorth’s next article will deal with the turning of boxes, trays, and bowls. Ping-Pong Table (Continued from page 1.12) bore a 5¢-in. hole through each post and the table rail to receive a 2)4-in. carriage bolt. To finish the table, fill the nail holes in the top with plastic wood cement or other putty suitable for bare wood. Then stain the wood brown to match the pressed wood, if that has been used, or dark green, if that color is pre- ferred and if a wall board of lighter color forms the surface of the board. Give the legs and rails two coats of shellac or varnish and the top the same, if desired. When the ping-pong board is used as a screen, the mass of brown or green may not suit the room in which it is placed. In this case in- stead of being stained, the board may be deco- rated in modernistic style or in any way pre- ferred, or a decorative textile may be used. Green denim or other cloth, or billiard cloth, may be used to cover the table for games. It should be cut to fit around the net posts and allowed to fall over the edge, or it may be held in place with snaps. Ping-pong sets containing rackets, balls, net, and the like, may be purchased at almost any store dealing in sporting goods. ACE HIGH in Character and ity! Neneh RE pen Care ee sg = KET a HOME aaa a home easy! You can now make an: ching on your own private work New Red Jacket Combina | my tools brings Red ee Saw werful Red Jacket Master Drill Motor with direct drive to Waco Craftsman’s w turn (cap. 9°x36"), compound and 18” tilt. top mitre saw with depth side gauges, scroll and jig d all accessories buffing, grinding and c socket and converts your werk ch in private tool and machine shop. ‘ty Make Thin sat Home Electrically | t it u private uoe of tool lo Le ‘men whe 4 Sum + oair ond coo ae ndy t home. Special Crafts Course and Blueprint Service Free | to Red Jacket Make It \ aca j t Yourself / oy Meme! Ft woods, sare | .* \ eawing, tura- 1 ir car a) pe i j | nteri with Waco 7 4 Mot taught ae Our Code of Busine ic - Ask 7000 Happy Waco Quwuers' Buy on Your Own Terms Liberal discount for cash. The Famous ee oa payments, LOO IMITA- TIONS. There is Red Ji ae nenee will find Toors U3 oid by retailers made direct from factory * Waco Guarantee If it is not what you want — you get it—send it for Interes Liter Send aF cou ou will ~ surprised resting Lice — ‘nstructive, Fascinating, Interesting. aaaauee FILL IN AND MAIL TODAYaeaeaa WACO TOOL WORKS, Inc. 5216 W. Kinsie St., Chicago. Hed Seckse Kontabline cad THER Beene ee TOMBiecccccscccceseccecesssess 6400000800500000e0600e0nnee icc cncincccces . eae | PARKS WOODWORKING MACHINES $290 You ought to have this handy Parks in your shop. Compact, complete machine de- J 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., Cincinnati, Canadian Factory: 3388 Notre Dame H’DQUARTERS —Shi We can suppl. ial construction semi-finis and all sorts o: S aon i-finished hulle and all f D —Power F ats tings such as anchors blecks, center aes _ Ss, ns, E ey ngines wee Bae, Soure beats, se chocks, —Sail Boats davite, etc.) for Flying Cidud, L —Supplies stitution, Sovereign of the Seas, Moon, Spanish eon, Mis: River Steamboat and many others. Also construction sets for model power ts an 1 sail ts. Steam em gi ers, blow torch, lt cou: ES) materials such a8 , ete, 3-ply. veneer, La ny sa photographically lust ly rt strated “Lgege af passe and hints for Ohio . East, Montreal pebroary, 19 two-tor bargain A nev console Very 1 Electre netic-P Above combi Speak: ee ® This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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5. rrr Te ores @ FE ma! os setts dade Poort | = ss oPpres Ws february, 1929 POPULAR SCIENCE MONTHLY 119 FACTORY TO YOU~SAVE 50%-COMPARE WITH COSTLIEST OUTFITS BEFORE YOU BUY Fnj00 ap owerful hew i; AC Electric or Battery JURA NIEW FACTORY PRICIS | SAVIE 502 LOW leaf desk. bargain! console. netic-Power Speakers. At right, A gem! A popular walnut Hi- Boy Console, with drop- Beautiful two-tone finish. Rare A new-type arm-chair Genuine walnut. Very pretty. Low priced. Electro-Dynamic or Mag- Boy console, walnut finish, thatcostslittle. Above, popular inexpensive combination. Set on Table Speaker (sold separately). Wide Selection of Beautiful Cabinets AC or Battery Sets 30 DAYS HOME TRIAL Richly designed, gen- uine walnut console of finest type. Elec- tro-dynamic or mag- netic power cone, or long aircolumn speaker. Marvelous value. Beautifully graceful Spinet console, genuine two-tonewalnut.Choice of speakers. Also comes in Electric Phonograph- Radio Combination. a Lo- Metal or wood compact style cabinets. Wood cabinets in walnut os new shaded silver- chrome finishes. Cathe- dral Electro- Dynamic or Magnetic-Power Speaker to match! = -up connection al features. Built eqnes section on A The Latest, Finest and Costliest Construction 3 Year Guarantee Electric Lighted CATHEDRAL TONED, SUPER SELECTIVE, POWERFUL DISTANCE GETTERS Celebrating its 9th successful year, America’s big, old, reliable Radio Corporation springs a genuine sensation in high-grade sets. With its latest, Super-powered, 1-dial hum-free operation, tremendous “kick” on distant stations and razor-edge selectivity—with its costly sturdy construction, latest features, including phonograph Miracos—the All Electric wholly self-con- BIG DISCOUNTS pick-up connec- tion, ease of tun- ing, beauty, and : # Exclusive Territory reve free ACS and to User-Agents on Miraco’ will AC-9, using AC # BATTERY OR AC §@ make you the tubes or thenew § ELECTRIC OUTFITS § covy of many 8-tube models whose radios for batteries or Eliminators—you are guaranteed values and savings unsurpassed in the fine set field. Compare a Miraco with highest- riced radios, for 30 days in your ome. Surprise and entertain acd friends—get their opinions. Unless 100% delighted, don’t buy it! Return everything—the com- plete outfii—at our expense. Your decision is final—absolutely! Only exceptionally fine radios, of the very latest approved type, at rock-bottom prices, could possibly back up so liberally unconditional a guarantee. Send coupon now for ¢ Amazing Special Factory Offer! Don’t Confuse with Cheap Radios With its rich, clear Cathedral tone, Miraco Outperforms ’em All In On the Miraco Unitune, to start with, will oor: ic 61 stations outside of Chicago, f1om the Paci Atlantic Ocean, and from Anchorage, A Mexico, and I tried the set with 3 is an outside aerial 152 feet, an inside aerial 20 feet, and jest to date laska, to the Gull of (names expensive make), and beat that one. Next I put ft ifferent antennas. That up against a Neutrodyne and beat that one. HARRY KOPP, 6555 South Peoria Street, Chicago, Illinois. cost 2 to 3 times as much! Many thousands of Miracos— bought after 30 day home com- arisons—are cutting through ccals and getting coast to coast with the tone and power of costly sets, their delighted users report. Miracos are laboratory-built with finest parts, and embody 9 years’ actual experience in constructing fine sets. Approved by 0's highest authorities. “ Deal Direct with Big actery thi hes idly packed re ‘higidly tested 2 aieee vom instant enthusiasm. Enjoy the outfit 30 days— hen decide. Liberal 3-year guarantee on each set. Play safe, save lots of money, and insure satisfaction by dealing direct with Radio’s old, reliable builders of sets—9th successful year. AC-8—$71.50 Unbeatable value in a 3- ear guaranteed Super Shielded Metal Chassis. Also New, More Powerful Battery Sets The newest and latest im electric sets! Same_wide chatce ¥. tJ a est quality,amazinglylow priced! light socket. I want to say that your set does outperform the other sets I have. I put it up against a World Record Super 9 and beat that one. Then I put it up against a MIDWEST RADIO CORPORATION, 408RF Miraco Building, Cincinnati, Ohio BEAUTIFULLY ILLUSTRATED CATALOG, AMAZING SPECIAL FACTORY OFFER, TESTIMONY OF USERS=All the proof you want—of our honesty, fairness, size, financial integrity, radio experience and the performance of our sets—including Amazing Factory Offer—sent with catalog. -. el MIDWEST RADIO CORPORATION THIS COUPON Pioneer Builders of Sets—9th Successful Year © 408RF Miraco Bidg., Cincinnati, Ohio AN ORDER WITHOUT OBLIGATION, send free catalog, Amazing Special Factory Offer, testimony of nearby users,etc. ( User © Agent O Dealer 0 Check here if interested in an EXCLUSIVE TERRITORY PROPOSITION 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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a a eee other Hammers like MAYDOLE Built with as much care as the finest preci- sion tools, Maydole Hammers have been the choice of skilled Amer- ican craftsmen for more than 85 years. The heads are press-forged from the finest tool steel ob- tainable and the handles are carefully shaped from clear, second growth hickory that has been thoroughly sea- soned and put into the heads “for keeps.” Every one has that remarkable Maydole “hang.” Driving or pulling, there’s more in a Maydole than in any ordinary hammer. Your hardware dealer carries a complete stock, ask him to show you the style and weight you prefer. Write for a free copy of Pocket Handbook 23 “B.” Waydole Hammers The David Maydole Hammer Co. Norwich NY 2468 POPULAR SCIENCE MONTHLY Model Railway Control (Continued from page 78) train from going too fast and being wrecked. The double-pole switch is wired as shown in Fig. 5. Check this wiring and you will find that when the switch is thrown to one side, the full voltage is supplied to one grade, and the volt- age to the other grade is reduced by a rheostat that can be adjusted for down-grade running. This rheostat is shown on the control panel just below the double-throw switch. A train running around the track strikes the up-grade and receives the full voltage while it is climb- ing. When it strikes the down-grade, the voltage is automatically reduced. You do not have to make any hand adjust- ments on account of the grades, even if two or more trains are running on the track at the same time. Of course, if one train is faster than the other, you will have to stop the faster train at intervals to prevent it from overtak- ing the slower train. But if your railroad is equipped with an automatic block system such as was described in the December, 1926, issue of PopuLar Scrence Monrua.y, page 70, the trains will require no attention whatever. ‘THE double-throw switch is provided so that you can reverse the voltage control to the grades when you desire to operate a train in the opposite direction. The voltage changing switch on a small transformer necessarily must be made so that the current will be cut off between switch points. The automatic reversing locomotives are of the sequence reversing type. Each time in cut off the current and turn it on again the ocomotive starts in the opposite direction. Therefore you cannot change the voltage while the train is running unless you stop and start it all over again. This is rather awkward when you want to increase the voltage to take care of an additional train. There is, however, a way to overcome this difficulty, and the remaining switch on the con- trol board accomplishes this result. Near the lower right-hand corner (Fig. 3) you will note a small lever projecting through the board. This is a standard type two-way electric light switch of the toggle variety. The usual metal plate has been left off because it would spoil the appearance of the board. The wiring is shown in Fig. 4. In one posi- tion current for the track is obtained from one transformer terminal, and in the other position current is obtained from a higher voltage tap. The secret of this switch is that it snaps from one pesition to the other so rapidly that the re- versing mechanism in the locomotive has no time to operate and the train continues in the same direction with no apparent break. This switch, plus the rheostats for minor variations, will permit you, to obtain a wide range of control. Figure 2 shows the underside of the control panel. Ordinary bell wire is used throughout. As supplied by the manufacturer, each elec- trically controlled switch has a three-wire cable leading to it from a flat type two-way switch. The white threaded (Continued on page 121) Ss Sorire- wee wares es TORR ee eee CONE Win om TO _12-VOLT TAP 3 BUTTONS ON TRANSFORMER Fig. 6. How the three switches of a Y are con- trolled as a group by the three push buttons. | ris] This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. Business Here’s g Big Opportunity for men who want g et ahead ing erma Well Paying Business Seat th ‘, selves. Hundreds of men are making Big Money with the Foley Auto. matic Saw Filer. Nothing'elge like it in the world. Files saws better than by hand. ition with No Com FOLEY £379; SA W FILER You can get ali kinds of saws to file~ from carpenters, contractors, saw factories, schools and every other ki business, because the Foley files them AUTO. MATICALLY with such mechanical acy that they cut faster, cleaner and truer Fuller Made $3 in 40 ‘ When your customers see h i sharpen their saws on the Foley, vot umm PERIENCE NERDED to toate AO 0 op —fast, accurate work AUTO. the Foley MATICALLY. 5 to 8 hand saws an hour is easy work, Big | be rely eer tg Peo hf ete Foley Saw Tool Co:, Inc,, 1005 Foley Bidg. gi ain St. N. E., Minneapolis, Minn. r | Gentlemen: Please send me Free Plan showing how can make BIG MONEY in my sp8re time filing saws oof the Foley. i OMEDs « «.0.00.60.00000060000060600566666500mnmE : cme WITTTTITITIT TLL TTT TT TTT TTT. { Breed squabs al make money. Sold TWO by million a prices that chickens, at once for tor free books tel ing how to & it, One is 48 pages printed in colors, other 32 for Books 3 and 4. You will be surprised. , Rock Squab Company, 616 H Street, Melrose lands, Massachusetts. Established 28 years. ence, any bank or trust company. A Beauty—Full of Fire . Latest Sterling engraved 1929 De rt po hi ni eae SE bas tell it frome $2001 Diamond, in Bi] , Don't Senda Fenny! ; st send name, ess $2-dand potwe, Satisfaction Order Today! Foreign HB PAINT , SPRAY OOES THE WORKOF FIVE, MEN QUICK, EASY PROF Practically no investmem) Small space required. Stead a by and —_ Preece au urnit ure—pain' houses and barns with HB qui ck 30 DAYS TRIAL 1 QUICKLY PAYS J | FOR ITSELF. - ELITE JEWELRY HOUSE 924% ScstA3Nar’ Mite | P

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pebruary, 1929

POPULAR SCIENCE MONTHLY 121

— : | Model Railway Control Be (Continued from page 120) | gire of the three connects the arm of the + | gwitch to the third rail. The green and red led wires connect the contacts of the gwitch with one end of each electromagnet, the wire from each electromagnet being led on the running rails of the switch. - In wiring the switches for push-button con- trol, you may d | ed wires to the control board. The wire that lies current from the transformer to the third rail by way of the toggle switches can also be connected to one side of each of the switch control buttons.. The remaining terminals of these buttons can be connected to the red and green wires from the switches. F YOU install independent control for each switch, you will need two buttons for each switch, but a group control will save buttons and prevent mistakes in operation. The grouning of the switches will depend on track layout, and a little study will be re- jred to determine the best arrangement. As an example of what may be done in this direction, examine Fig. 6, which shows in pic- ture diagram form the simplest connections for a Y. One button is connected to the green wires from the two switches on the main line. The second button is connected with the red wire from the left-hand main line switch and he green wire from the Y switch. The third } patton applies current to the red wires from the Wand right-hand main line switches. > Pressing the first button clears the main ine, no matter how the switches were set before ‘the button was pressed. A touch on the second $utton sets the switches for a train going out to the left or coming from that direction. The third button allows trains to travel over the Y to the right. Similarly, two buttons will control the two switches that are used in a crossover; and in the terminal you can provide one button for throwing all the switches to clear the track to the last siding and have individual buttons for controlling the other positions of the switches along the track that lead into sidings nearer the main line. Weatherstrip for Bottom of Storm Door i\\"" PIECE OF OLD INNER TUBE Be) | | | an mM eeu) 1) - STORM DOORZ == ~ = Storm door with a doubled piece of inner tube applied to keep it weather-tight at the bottom. INGED weatherstrip with a rubber edge, such as is often fastened at the bottom of a storm door, is apt to be more ornamental than effective, but a weatherstrip may be made of an old inner tube that will accomplish all that can be desired in keeping out wind, } tain, and snow. Be sure the bottoim of the door clears the threshold by 4% or % in. - Prepare a piece of board 41% or 5 in. wide and the width of the door opening in length, to be used as a pattern.

a piece of old inner tube lengthwise and } } Spread it open, flat and straight, upon a board; fasten it lightly with tacks, without stretching. Lay the pattern upon the tube and with a sharp mnife cut accurately around the board. 'y Fold the rubber lengthwise in the middle and h it lightly with cement an inch or two tach side of the fold, but not near the edges, to ‘hold it together while it is being tacked to the ide of the door.—C. A. K.

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Easy Terms eee ----- Se Ar-Con Utilitool units may be pur- | The Ar-Con Tool Company chased singly or in any combination of 500 Fassett Street, Toledo, Ohio units if the complete outfit is not required at the start. Moreover, the | purchase can be made by convenient | time payments, if desired. The cou- pon will bring fully illustrated descrip- , tive circular and complete price-list, | Street Address with terms. Mail it now. Mail descriptive circular on Ar-Con Utilitool, with prices and terms.

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

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LY LRN FA Toe “4153 Madison Ave., Fir st A id for Builders o Ship Models cAncient and SModern Plans—Scale Blueprints of historic and modern vessels, racing sail yachts and power boats Lumber—Selected white pine for hulls, straight grained spruce for spars, three ply veneers for decks, mahogany, etc. Tools—Specially designed—Chisel—Gouges and Planes to fit exactly modelmakers’ needs Hulls—Made to Scale of selected white pine in the rough partly finished or completely finished ’ Boat Fittings—Blocks, Dead Eyes, Turnbuckles, Cleats, Chocks, Davits, Airports, Capstans, Binnacles, Rigging Line, Sail Cloth, etc. Model Sailing Boats—Complete ready to sail or construction sets Model Power Boats—Complete ready to run or construction sets Marine Engines—Complete Steam Engines, Construction Sets in different stages of com- pletion, spring motors Steam Boilers—Made of seamless tubing, boiler fittings, blow torches This booklet has many pages of information useful to modelmakers, model yachtsmen and others on sailing Model Yachts Brief history of Steam Engines Illustration of famous models made by the House of BOUCHER Nautical terms in common use Parts of a — vessel—spars, rigging, knots, hitches and splices commonly used on boats Hints for painting and finishing Model Boats Whatever type. of ship—sail or steam— ancient or modern—you are building or lanning to build, you will find the book- et ‘Scale Models’ of tremendous help to ou. Send 25¢ today for your copy. It will be sent to you by return mail. Headquarters for Model Makers for 22 Years Dept. F.S. New York Geaslemen: Enclosed is 25c, for which please send me your booklet, “*Scale Models.” POPULAR SCIENCE MONTHLY A. February, iy Building the Buckeye State (Continued from page 92) Gievee TRACK RUDDERPOST g DIA. HOLES Fittings at the stern of the model, including trusses, hog chains, ladders, rails, and rudders. lower and upper handrails and where the edge of the upper deck comes. Apply a similar piece inside along the top edge. Unless the weather is very humid, these pieces will have to be dampened by dabbing them with a moist cloth before they are applied; otherwise, however well glued on, they will buckle in damp weather. Glue them on and hold them in position un- til dry with glass-headed pins (these are sharp and easy to handle). Along the inside of the upper part—and the lower, too, if you wish— some thin strips of wood from the rail to the deck will look well and stiffen the whole. Give the whole one or two coats of flat white paint and a coat of white enamel. EXT should come the deck on the cabin, which is similar to the other decks and pro- jects a full }% in. all around. Also put on the texas hecause its bulk can be easily grasped and will save the handrails and other delicate parts from damage in handling the model. The texas of my model, as shown in the upper photograph on page 92, has not as many windows as it miight have because I had doors between and then found when all was finished that there would have been no way in which anyone on board could reach them, so had to cover them up. The texas can be made by either of the methods described last month, but preferably by the built-up method, which leaves it hollow. The lines of its sides will coincide with the _ square abaft. There should be two docs al ——__ side lines of the cabin. It is round in front ‘for entry. It will have a deck similar below. to thon The hog chains (Main Chains No. 2) should now be fitted. For the after strut bore both decks into the top of the engine paint the strut black, and glue it in pogitt extending above the upper deck % in, For the forward one we already ,have holes in the lower decks; make another in the upper in ling with them and put it in position to extend 3@ in. Bore holes for the wires, then reeve th ends down through. Turn up the forward en of each and drive it into the hull, stretch it ove the struts, draw it down tight aft, and turn th end up. Do this on both sides, of course, PLACE the forward and after ladders in posi. tion. The forward ones need handrails on the outside only. The after hole needs a on three sides, but the forward ones, where the deck is so narrow, need be guarded on only two sides. Note that the side supports of the fon ward guardrails are on the top of the cabin and are shorter than the posts which extend from the upper deck. On the original model the upper ladder hand. rails are of brass wire and the lower of wood, We have yet to put the four slanting crog timbers on either side between the lower decks, They extend from main to boiler deck and am similar to the lower stanchions; they are nailed outside all. Their positions are shown ¢ on Blueprint No. 96 and in the upper photo graph on page 92. The boat davits, which also are shown o Blueprint No. 96, may now be put in position, They are merely square posts, glued to the deck edges outside everything else and per lashed with thin thread to the upper h They have the smallest possible double blocks lashed to their upper ends on the outside. These and the lower stanchions should be painted white. The lowest handrail may be white o@ mahogany color. Before we build any higher we had better make and fix the rudders and stern wheel. There are three rudders moving in unison, as shown in the drawing (Continued on page 124) CARDBOARD LLLLSCLIULTLAD A PLALLPSIS ST oa. VLLSDASSAAISILSESSPSPS LS ST INSIDE VIEW POSTS OF THIN WOOD EVERY THIRD ARCH The Bristol board rails are prepared in two OUTSIDE VIEW CARDBOARD long pieces, one for each side of the model.

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son, ag ge 124) Pebruary> 1929 O matter how lacking you are in qualities of leadership, no mat- ter how colorless, timid, unsuccess- ful and discouraged you may be, I GUARANTEE to so magnetize your mality that your whole life will becompletely transformed! I can give you poise that banishes self-consciousness, charm that makes you irresistibly popular, personal wer that will in- delibly influence the minds of others and amaze your friends. I'll make you a fas- cinating force in so- dal life, a powerful, dynamic, command- more prosperous, ‘more gloriously suc- cessful than you ever dreamed possible! Let me send you the proof—absolutely free! If within 5 days you do not experience forever, that seems Dont Pay Me a Cent ‘If 1 Cant Give You a Magnetic Personality -5 Days FREE Proof! What is that magnetic, powerful influence that draws one man to one woman— f irresistibly? is that strange, never-failing and power resources spark that awakens love? hat is it, in man or woman, fascinate—the hypnotic power that no one can resist? _. You have it. Everyone has it. But do you use it? POPULAR SCIENCE MONTHLY marvelous personal force, released and magnified a hundredfold in an amazingly clear-as-crystal, scientific way! More necessary than good looks. More valuable than money. For without it a salesman is hand- cuffed! Without it a business man is powerless to command! No actor, no teacher, no orator, no statesman can long hold his au- dience spellbound without this supreme- ly influential mag- netic force! Personal Magnet- ism! How easy to release it! How wonderful its results! No long study or in- ing figure in your convenience. Not the ‘profession. You'll be- a Is Sex slightest self-denial. come more popular, agnetism: Just a simple, clear, age-old principle, that — taps the vast thought within you, releases the full sweep of your magnetic potentialities and makes you almost a new person from draw and a decided change in your personality, if you do not find yourself making new friends with tase, if you do not discover yourself already on the way to social popu- larity, business success and personal adership—just say so. Tell me my Principle of personal magnetism can’t do every single thing, that I said it would do. And you won’t Owe me one penny! What Is Personal Magnetism? What is this marvelous force that faises the sick to glowing, vibrant health, the timid to a new confident Le Bee Lee ee Ne Ptsonality, the unsuccessful to posi- ‘tions of wealth and astonishing power? ' You have it—everyone has it— ‘but not one person in a thousand knows how to use it! It is not a fad for a theory. It is simply you, -yourselfi—your manner—your own what you were before! Personal Magnetism is not hypnotism. Hypnotism deadens. Magnetism awak- ens, inspires, uplifts. Personal Magnet- ism is not electricity. It is like electricity in one way—while you cannot see it, you can observe its startling effects. For the moment you release your Personal Mag- netism you feel a new surge of power within you. You lose all fear. You gain complete self-confidence. You become al- most overnight the confident, dominant, successful personality you were intended to be—so fascinating that people are drawn to you as irresistibly as steel is drawn to a magnet! The Facts Are Free The fundamental principles of Personal Magnetism have been put into an extra large volume under the title of “Instan- taneous Personal Magnetism.” It is bound in beautiful dark burgundy, with the title gold ,embossed. Its sco is as broad as life itself. ‘Fires of Magnetism.” ‘Sex Influences,” ‘‘ The Magnetic Voice,” “ Phys- ical Magnetism,” “‘The Magnetic Eye,” ASD) S A Ps 4 > ssceeemenrseanmeninrerenasty = = = = = = = = = = = = = = = = = = = = = = = = = = = = = + 2 = My > Ye, ‘YY CTTTITIT Ie PEN DEUEEBA BADE EELNNY “Oriental Secrets,” “Rapid Magnetic Ad- vancement,” “‘The Magnetic Mind,” and “Magnetic Healing,” are only a few of the subjects covered in this amazing book. A magnificent book that tells you just how to cultivate the magnetic influence of your nature. You can sway and control others. You What Others can command suc- cess. You can in- Say! fluence people to do “Has been worth ten the things you want thousand dollars a year. them to do. Through “1 am glad that 1 this amazing book | 44% Duy the books.” you gain the key toa magnetic personality in 5 days—or you “The Personal Mag- netism books have raised me from poverty to my present position. don’t pay one penny. “There is nothing This is my free offer | better.” 4 to you! “1 would not part with them for any sum Send Coupon | %™"” « f th Today man Tove wh ayer You must see this } istene"""" ™ wonderful volume— examine it—let it influence indelibl our own personal- ox, You send no money with the cou- pon — you pay no cx @ b. ou get the book first. If you aren’t stirred and delighted in the 5-day period, return it and it costs you nothing. Otherwise keep it as your own - and remit $3 in full payment. You are the sole judge. You do not pay unless you are absolutely delighted. And then only $3. You simply can’t delay. Clip and mai the coupon NOW. “Made me a success — financially, socially and morally.” “1 regard it as the biggest and best invest ment & man could make. Realized the experience of entering a new realm of life.” “Certainly wonderful; like walking up a stair way to a higher life.” “Heve examined ‘Per sonal Magnetism’ and am astonisned -ow dormant my facu.cie: 7ere im that direction. Ralston University Press Dept 14-B, MERIDEN, CONN. RALSTON UNIVERSITY PRESS Dept. 14-B, Meriden, Conn. All right—I’ll be the judge. You may send me the volume “Instantaneous Personal Magnetism’’ to 5 days FREE EXAMINATION in my home, Within the 5 days I will either remit the special low price of only $3 or return the book without cost or obligation. PROIAG sc 0.0.0. 00060086000606005006000b0000R0s0ReEE BABI 06 icc beicircdecevsccsededccnbessevesen e City emer reer ereseeeseeeeeee BeatGs, oc cases eceee

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POPULAR SCIENCE MONTHLY | Valve tappets and check nuts do their turn with ease and grace when gripped by these B& S Tappet Wrenches — Long, lean, light wrenches which handle just right for hair-fine adjustments. Ample clearance forhands. Correct angle for ‘‘close’’ work. Easily held away from hot motor. TAPPET WRENCH SET No. 46 Two pair of B & S-formula Chro ew ey wrenches, to fit mall Standard nuts and capscrews 2” to %”. Different-size openings af either end. 8 inches Iong with 22}° a le heads, Zuaranteed stronger pandier an any other des in of pepe roportions. LIFETI S, forged for the - bm In canvas ease, $9.30 the set. Visit our forges and see your wrenches in the making. the ©. . SpENCER GS & Compan eng e o , New York: II Park Place Chicago: 565 W. Washington Blvd. The Buckeye State (Continued from pdge 122) on page 122. They must be accurately fixed so that they will be almost in line with the boat’s bottom and allow the wheel to turn in their curve. They can be of wood or metal, the former being the easier to use. They had better be in one piece with their posts. Note that the. outside posts are short, but the center one extends just through the boiler deck, because that rudder has no, support under the main deck. Into each sternpost drive eyes made of pins, and into the outside rudders drive and bend over pins to fit in the eyes. For the unison gear make three tillers: one long with two holes, and two short with one hole in addition to the necessary square holes which fit tightly on the rudderposts. The tillers can be made of sheet tin or copper. Join the three with a bar having holes which correspond with the distances be- tween the holes for the rudderposts. Rivet the bar to the tillers with escutcheon or large pins. Pass the rudderposts through their holes and set the tillers on them at an upward slant so that the center tiller rests on the railway previously installed. Set the pintles in the rudders into their gudgeons in the sternposts and drive a pin through the center rudderpost above the deck to prevent it from dropping lower than the others. The wheel and remainder of the fixtures will be described next month. Mississippi Books DDITIONAL information about Mis- sissippi steamboats and many facts about the dramatic history of the Valley can be gained from the wn A listed below. The list was prepared by Captain McCann during the careful study he made of the literature relating to river steamships. He found ow interesting and valuable the books that are starred. Those volumes which have the price indicated can be obtained through the Book Department of Popunar Science Monta ty; the others, the majority of which are out of print, are available in many public libraries. American Steam Vessels, Samuel Ward Stanton. es History of Steam Navigation, A. G. H. Preble. Down the Great River, Willard Glazier. Early Western Travels, Ruben G. Thwaites. Early Steamboat Travel on the Ohio River, Leslie S. Henshaw. Fifty Years on the Mississippi River, Emerson W. Gould. *Genesis of Steamboating on Western Rivers, Geo. Byron Merrick. History of American Steam. Navigation, John H. Morrison. * Life on the Mississippi, Mark Twain ($2.50). Life on the Western Rivers, John Habermehl. *Mississippi River,- The, Julius Chambers ($5.00). ** Mississippi Steamboatin’, H. and E. Quick ($3.00). Old Times on the Upper Mississippi River, Geo. Byron Merrick. Progress of Navigation and Commerce on the Mississippi and Great Lakes, John W. Mor- metts, Steamboat Days, Fred Irving Dayton ($5.00). Father Mississippi, Lyle Saxon ($5.0). - A-Rafting on the Mississip’, Charles Edward Russell ($2.50). The _: of the Rivers, John T. Faris ($6.00). Show Boat, Edna Ferber ($2.00). The last four books are comparatively re- cent, and so great is the present interest in Mississippi steamboating that other books are certain to appear. The above bibliography does no J apery to completeness, but offers a fairly wide field for further study. A_ $100.00 SHipl| ¢ MODEL for $4.99 OB D thir I wa: el when I MAYFLOWER yly SIZE 25” High; 10” Wide; 26" Long at ET the World’s Largest Builders of Ship seem to supply fag with all the necessary parts cut to fitand Like a to put together for the models, M A Sante Mu Maria, or LaPinta. You need not know to the n about ship building to assemble one of theze models, 's, you have never seen a ship model you can put one of am these models together in a few hours by following our “You diagram and instruction eheets which explain and show : ted you exactly what to do with each part. All you need ig mnsistec @ smal} tack hammer to tap the parts in place, The leave it parte are numbered on the diagram, making it im rt possible for you to go wrong. These models when com Icity. . pleted are exact in every detail of the famous old Right they represent, and when eqpetatee will add a tinctive touch to your home. We also have Darte for the my model of the Constitution at $6.98; all other model se — tifal _Mlustrated booki taining Es “ ° photos and fort a on f our a just had MINIATURE-SHIP MODELS, Inc. to him, 3818-24 Baring Street PHILADELPHIA, PA, “Boy secten J 1 IP MOD nobod Soie-24 BARING ST PHILADELPHIA, PA. y Please send me the complete parts cut to fit and ready t» through Gab tage Set Ce NE ms {1 will pay Post. what a man $. ius a few cents for postage. Please p name and address plainly to avoid delay, trump ( Name, acocecconcccaccosce = your stc Streetor R. F. 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ae E34 EE Mi) ryt Bane & bie * vig EES if irestiat B . cried Bob as Be was always putting his foot into D things "J was spending my vacation with him when I met his cousin, Helen. Instantly all ‘other girls faded out of my life. It was love st first sight. But unfortunately she didn’t to feel the same way about me. Like all young lovers, I confided my troubles fo the nearest willing ear. It happened to be Bob’s. : “You’ve got nothing to worry about,” he insisted when I finished my tale of woe. “Just jave it to me. All you need is a little pub- * ” aah then and there I knew I should have t my mouth shut. The very next day he announced that he’d just had a long talk with Helen and aecording to him, “put me over big.” “Boy! What I didn’t tell her about you is pobody’s business!” he exulted. “When I got through with my little song and dance about what a whiz you are at the office, I pulled my trump card . . . and believe me, it boosted your stock sky high!” “What was it?” “Well, you see, she’s crazy about music. So [conveniently forgot that you can’t play a pote, and told her you are an accomplished 4 mistl’? “But Bob. . .” “Not another word! I’ve got you sitting pretty, now. If by any chance you're asked ‘to play—just say that you’ve sprained your wrist playing tennis. I’m some little fixer, eh, © what? bl That very night we were all invited to the “Carews’ party. On the way over, I sensed a “hig difference in Helen—a difference that made ‘ity heart beat fast with a new hope. Perhaps, ‘iter all, Bob was a good fixer. ie A little later in the evening we were all Mpthered around the piano, listening to the father indifferent performance of one of the “guests. | 1Am Asked to Play the Piano * “I’m just dying to hear you play!” cried f . “T’ye heard so much about your Vialent! Won't you play something for us?” » “Yes!” “Yes!” “Please!” came from all With a smile I bowed low . Wihat tt would be a pleasure. ) Glancing up I saw Bob’s grin change to @mazement. This was not part of the plan! . » and replied y ignoring his frantic signals I walked ver to the piano. Quick as a flash Bob tollowed me. “For the of Pete get away from that piano,” he = PyMhispered excitedly. “Don’t make a monkey urself. If Helen ever hears you play think everything else I told her is bunk, po!” "Turning to the guests in an effort to save own skin, Bob announced, “Perhaps we buld wait until some other time. You see, wrist was slightly sprained in tennis this J "Pe aiternoon, and . . “Oh, that’s nothing!” I broke in, and as Whe looked at me dumfounded, I sat down at piano. * * * & Without any further hesitation, and with a secret tmile at the surprise I had up my sleeve, I began the — POPULAR SCIENCE MONTHLY ‘Dont make a monkey — of yourself’ I sat down at the piano first notes of Irving Berlin’s famous “ Russian Lulla- by!” The tantalizing, irresistible strains seemed to throw a spell over the guests. One by one they quietly moved nearer the piano until soon I was completely surrounded by rapt listeners. Bob was so stupefied that all he could do was to stand there in open-mouthed amazement. On and on I played—losing myself in my music. I forgot Bob’s astonishment—forgot the glow of admiration in Helen’s eyes—forgot everything but the beautiful melodies that always opened a new world for my enchantment. Swept away by the sheer magic of Berlin’s genius, I was unaware of the silent tribute that followed my playing until thun- derous applause shook the room. That brought me to myself with a start. For the rest of the evening I was the lion of the party. Bob could hardly restrain his curiosity until we were safely home. “Boy! You sure stopped that party dead!” he exclaimed. ‘‘ You could have knocked me over with a feather when I heard you actually playing! Why didn’t you tell me you knew how?” “You never asked whether I knew how to play,” I countered. “Of course not! Last summer you didn’t know one note from another—how was I to guess you’d 125 blossomed into an accomplished pianist overnight?” “Not overnight, exactly!” I smiled. “Although it almost seemed that way! Remember that Free Demonstration Lesson in music I sent for?” “You don’t mean the one that was su to show you how to play without a teacher, do you?” “The same! All the fellows said it was a fool stunt and that I was crazy to send for it. Well, it happened to be the best bit of luck that ever came my way! I didn’t say anything about it because I didn’t want every one laughing at me when I sent ee course. That course certainly is wonder- “So you really are an ‘accomplished’ pianist! The joke’s on me, all right!” “Oh, I wouldn’t say ‘accomplisked,’” I laughed. “But enough of a pianist to get a lot more fun out of life than I used to!” You, Too, Can Learn to Play Without a Teacher The above story is typical. You, too, can learn to play your favorite instrument by this remark- able ‘‘at home” method that has helped almost half a million people all over the world to increased pleasure and financial gain. You don’t have to know the slightest thing about music. First you are told what to do—then a picture shows you how to do it—then you do it yourself and hear it. No private teacher could make it any clearer. You learn at home in your spare time. You study when you please—and as much or as little as you please. There are no tiresome scales—no laborious exercises. You play simple, familiar melodies by note right from the start. Free Book and Demonstration Lesson Our wonderful illustrated Free Book and our Free Demonstration Lesson explain all about this remarkable method. They prove just how any one can learn to play his favorite instrument in almost no time and for just a fraction of what old, slow methods cost. If you really want to learn to play—if new friends, good times, social popu- PICK YOUR INSTRUMENT larity and in- J Piano Violin creased income Jj Organ Clarinet take this oppor- asc = maa A ke ne Harp tunity to ma Piccolo Mandolin your dreams come § Guitar. *Cello Hawaiian Steel Guitar true. Now! Sign Sight Singing the coupon and send it before it’s too Piano Accordion late. Instruments bree bs nna supplied when Drums and Traps needed, cashor Automatic Finger credit. U. S. School of Music, 82 Bruns- wick .Bidg., New York City. U. S. SCHOOL OF MUSIC ] 82 Brunswick Bldg., New York City Please send me your free book, ‘Music Lessons 7 in Your Own Home,” with introduction by Dr. j Frank Crane, Free Demonstration Lesson and particulars of your easy payment plan. I am in- I terested in the following course: Con Banjo (Plectrum, 5- String or Tenor) t OC ccc ccccccccccesbe sees cohcesecssbees an oem ee | Have you above instrument? ..............ee0% ° FORMRD 0. 0 side Fake o4:b9 dsteustebaeiiene-aile alae ee I BROS «0 6: o:c''3s ccgcdintsa+aeshedega wee ee i CUE e cuca ond ctnaiaiasee daneaseal UR 65 3.604% oobe

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POPULAR SCIENCE MONTHLY

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Weship Lathe immediately upon receipt of small down payment, and give you 10 months to pay balance in equal in- stallments. With each Lathe we send Free Complete Instruction Book, “How to Run a Lathe.” Prices and Terms of 9-inch Junior Lathes cnet Tt. tes -teaee Tees _ tae men ‘aymen' 9x21, Tl in. 350 ibs. $30.00 $12.00 $150.00 9"x3’ 18in. 375lbs. 31.00 12.40 155.00 O"x3%’ 23in. 400lbs. 32.00 12.80 160.00 9" x4’ 29in. 425lbs. 33.00 13.20 165.00 9"x4%" 36in. 450lbs. (34.00 13.60 170.00 .. Write for FREE Time so oN ‘SOUTH BEND LATHE WORKS uth Bend, Ind., U.S. A. St. Se Bene. tS. Centre St.

@scor INVENTORS PANY We Build Models Send us your rough idea. Our Master Mechanics will Gevelop it for you into a practical working Model. irty years successful =» 7 doing this very thing. st shop equipment. xpert advice. Confidential Service guaranteed. Bank reference furnished. Send for free booklet “The Road To Success. ’ Crescent Tool Co. Dept. B Cincinnati, Ohio

Priced. Use 1 iP

Print Your Cards, stationery, labels, paper, circulars, tags, menus, ete. Save money and time, cut cost in half. Sold direct from factory. . Pays for itself in a short time. ey Complete Outfits, $8.85 up. ef Job Press, $11, $29; Rotary $149. Print for Others, Big Profits. All easy, rules sent. rite for catalog of presses, type, paper, eards, envelopes, paper cutters. The Kelsey Co., P-33, Meriden, Conn. Own This Better H&A Saw Table A sturdy, powerful, large capacity machine that will handle wide. rat material. Accurate, speedy, reasonably ing, ring, groovi vel sa t for ripp cross-cutti iteri be joing. Ee with tilting fence for wine . motor; fecaee spindle. ‘or catalog HESTON & ANDERSON 802 Market Street, Fairfield, lowa

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

‘tends to cling to the blade.

Decorative Metal Sawing | (Continued from page 76)

blade should be straight up and down, you come to a corner or sharp a push the saw forward at all, ri ro ut frame slowly as you move it up and ~ The. saw will cut a hole for itself to turn } then you may resume sawing in the usual *, On some types of work much time cap saved by drilling holes for the saw to tum; at all sharp angles. It is always necessary, d course, to drill at least one hole in each inter part which is to be cut out. The blade jy inserted through the hole after being loosened at - end from the frame. you rub a lump of beeswax or a candle the blade at intervals, it will help the sa en Brass is probably the metal easiest to saw, but silver and gold are both excellent. Copper Very thin metal such as No. 28 or 30 gage is best fastened with shellac to a piece ¢

BENDING LINES s

4 CSECTION WHEN FORMED H Fig. 5. How to lay out the design for the teapot stand on a piece of brass 6 in. square. cigar-box wood or even thick pasteboand, Later the metal is removed from its backing by heating it. Very thin, fine-toothed saws must be used for such delicate work. After practicing on scrap metal, the beginner can make the teapot “‘tile’’ or stand illustrated in Fig. 4. Brass is the best metal to use. First draw the design as in Fig. 5, or, bette still, make up a simple design of your ownd the same type and then transfer it to a piece : No. 18 gage clean flat brass. Scribe in the ines. The eight-sided shape may be cut out with a pair of stout metal shears, but it is excellent practice to saw to the outline. Drill a holeia each interior part and remove any roughness left by the drill on the underside of the metal. Next saw out the design; then file the cut edges on the bench pin as shown in Fig. 2 using small needle files and larger half-round or crossing files, which have very fine teeth. Leave no raw edges; all must be well rounded or chamfered. Fairly coarse, followed by fine, emery cloth, if torn into narrow strips, may be used to smooth down the edges after they have been filed. For this work hold the tea stand between the vise jaws, but place pape to protect the metal from the jaws.

The edges may be turned down over a cleait cut block of wood held in the vise as in Fig. % Do the hammering with a wooden mallet, The corners of the bent-over parts do not need to be soldered. Polish or finish the piece B) any way you wish. Many similar projects, such as blotter cot ners, paper knives, and watch fobs, may be

made in the same way as the tea tile. ae

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eboard, 7S must Sf it i iad he i 1e tea = 3

Fastening Objects to Plaster Walls Paste this Home Workshop Refer- ence Sheet, including the head above, in your scrapbook in the sec- tion marked walls. (Feb., 1929, POPULAR SCIENCE MONTHLY.) How do you drive nails in plaster walls ? AILS will hold in plaster walls only when driven right through the plaster into one of the wall studs, or uprights, to which the lath is fastened. To find one of these uprights, tap the wall very gently with a hammer and listen to the sound. The sound is hollow in tone except where the studs are located, and there is a perceptible difference in the re- bound of the hammer. If you find it to be difficult or impossible for you to detect these differences, look at the baseboard and note where it has been nailed. The nails are driven into the studs, and there ‘js usually good nailing at any point in a ver- tical line directly above them. Drive a thin finishing nail carefully through the plaster to make sure that the stud has been located. Studs ordinarily are placed 16 in. from cen- ter to center; you can, therefore, locate other studs by measurement after the first is found. If large nails are to be used, drill holes through the plaster so that it will not be chipped. Use an ordinary twist drill, fluted drill, or gimlet bit. How can something be fastened to a plaster wall at a place where there is no stud to give good nailing ? 1. Obtain a toggle bolt (see the illustration below) of suitable size and drill a hole to receive it. Plumbing fixtures, clocks, shelf brackets,

TOGGLE BOLT IN BO PLACE

METHOD OF INSERTING BOLT = PUSHLESS X HANGERS ; Toggle bolts for use in pilaster or ocher hol- low walis; smail hook for plaster or wood. and other articles of considerable weight may be fastened with toggle bolts. 2. Light objects, such as pictures or mir- rors, can be hung by means of the hooks or “pushless”’ hangers shown, which are sold in various sizes according to the weights they are intended to support. These may be used any- where, without reference to the studs behind the plaster. Drive the pins carefully, espe- cially the larger sizes, (Continued on page 128)

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New Model South Bend Back Geared Screw Cutting Precision Lathe More than 42,000 in Use in U.S. and 78 Foreign Countries

New Model |» South Bend Junior Lathe |” equipped with Horizontal]? Motor Drive. | Same lathe as illustrated at |- right except with motor drive added. Connects to any ordinary light socket for power. Price with Motor ....secsesccee evcces ecerece 226

13"x5’ Quick |i 4 Change Gear |) Lathe. Back |4 Geared, Screw Cutting. Com- pound rest,au- |) tomatic feeds |) to carriage. 1’ |~ hole through | ~ spindle. Phos- |. phor bronze] ~ spindle bear- bie ings. Weight, 1110 lbs. Com- lete with Conta and Equipment, ete with Countershaft eee eee eee eee ee $402 16’’x8’ Quick fF Change Gear |~, Lathe. Back Geared Screw Cutting. Com- pound rest,au- tomatic feeds to carriage, 1%” hole through spin- die. Phosphor |” Bronze Spin- dle Bearings. Weight 2035 , ’ Ibs. Complete with Countershafe and Equipment. Easy Payments if Desired You can secure any South Bend + ‘di lathe by making a small pay-,¢ 4 ment with your order, and YA Fp take care of the balance in ,% sae small monthly payments M SEES” ? over a period of 10 4 Se months. We ship , “ " PEO Hs ‘gl down pay- 4 Ae Sy" os Pa ment is re- ee ceived. ,

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Hi L head Seat sdhests ' all car: outfits SPORT FACTORIES ‘Dept. D-3 ‘AURORA, ILL. IS] This seal on an advertiserrent in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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PLASTIC WOOD? Reg. U.S. Pat. Off. What if a fixture has pulled out—and towel racks, glass elders, and other fixtures set in tile do come loose ?— it is easy enough to fix them perma- nently with Plastic Wood. Just clean the hole to remove loose plaster, wood, or dirt and fill it up with Plastic Wood —the amazing household product that handles like putty and hardens into solid wood. Then, when hard, screw the fixture back in place— or, if it has no screws, ‘‘set”’ it while the Plastic Wood is still soft. PLASTIC WOOD [Reg. U. S. Pat. Off.] It comes in two forms—Plastic Wood, of natural wood color, and Plastic Wood White Waterproof Tile Cement, which dries to a hard flat white, and is particularly useful around loose tiles and other places in a tiled bathroom where a white finish is desirea. Plastic Wood is waterproof, greaseproof and weatherproof. It has a thousand uses indoors or outdoors, and for the handy man it nelps in almost any wood-working job for sealing joints, filling cracks, moulding, or repairs. Plastic Wood Solvent When working with Plastic Wood, keep a can of Plastic Wood Solvent on hand to soften Gv if it hardens too rapidly, to thin it if neces- Sary, and to clean the hands and tools after using. At dealers, in 25 and 50 cent cans. Hand Hardens like into Putty Wood | ' 1 Ib. $1.00 % Wb. 35 cts. At Hardware and Paint Stores ADDISON-LESLIE COMPANY 312 Bolivar Street Canton, Mass. POPULAR SCIENCE MONTHLY Plaster Wall Fastenings (Continued from page 127) to avoid chipping the plaster. Indeed, it is better when the larger sizes are used to take the pains to drill holes at the correct angle for them. To drive one of the pins, first withdraw the pin until the hook can be held firmly against the wall; then drive the steel point home. How do you drive screws in plaster walls ? 1. Locate the stud behind the plaster as previously described and drive a 1)% in. long screw through the lath and plaster into the wood. It will penetrate the stud about 34 in., which is usually far enough to hold any ordinary picture or other object. Before driving the screw, drill a hole through the plaster of a diameter equal to the unthreaded part of the screw, and a hole in the stud a trifle less in size than the root diameter of the threaded portion of the screw. 2. When no stud is to be found in the posi- tion desired, use a toggle bolt as described in the first answer to the previous question. 8. Drill a hole in the plaster just large enough to receive a prepared commercial fiber plug of the kind illus- trated. This has a small hole through the center into which the screw is driven. The fiber wedges and binds the screw tightly in plaster, tile, cement, stucco, and similar materials. 4. Between studs it is often possible to drive a 114-in. screw so as to take good hold in a wooden lath. Such a screw will usually hold surprisingly well, but sometimes it will fail. A toggle bolt, mentioned in paragraph No. 2, is far stronger. 5. For very light work, a hole can be drilled in the plaster a little larger than the screw and filled with patching plaster or plaster of Paris and water. Turn the screw gently into the soft filling and with a knife smooth down the plaster around the screw. If it is desired to have the screw removable, the threads should be wrapped with copper wire and both screw and wire pressed, not turned, into the plaster filling. The wire is held firmly when the plaster hardens, but the screw can be turned out. This expedient is more useful in connection with cement walls and floors, in which case Portland cement is used instead of plaster for embedding the screw. Iron cements and plastic wood preparations are often ysed in the same general way. In no case should any weight or strain be put on the screws until the cement has become thoroughly hard. Ai BR Y em evassaego ’ ' —— PLUG Special plug for use in plaster, tile, cement, and stucco. How to Waterproof Shoes G HOES can be made waterproof or at least highly resistant to moisture by the use of one of the following formulas recommended by chemists of the U. S. Department of Agri- culture: Formula 1: Neutral wool grease, 8 oz.; dark petrolatym, 4 oz.; paraffin wax, 2 0z. Formula 2: Petrolatum, 16 oz.; beeswax, 2 0z. Formula 3: Petrolatum, 8 oz.; paraffin wax, 4 0z.; wool grease, 4 oz.; crude turpentine gum (gum thus), 2 oz. Formula 4: Tallow, 12 0z.; cod oil, 4 oz. Which formula to use depends upon the ease with which the materials can be obtained. These ingredients must be melted before being mixed and applied warm, but not hot, to all outside parts of the shoes or boots. The soles are then saturated by setting the shoes or boots in a shallow pan with sufficient melted grease to cover the soles. Rubber heels, however, must be kept out of the mixture. February CAMPBELL’s INFRA-RED RAY LAMP ee Me Have Ven Some Troublesome Ailment? You will be greatly surprised when you learn hoy Infra-Red Rays relieve congestion or troubles i aches and pains in the body. The Campbell Infra. Red Ray Lamp concentrates a mild beam of Infr,. Red Rays upon any part of the body. These rays penetrate deeply into the tissues, Ag they penetrate they create an active circulation of the blood. Most ailments are due to congestion— relieve the congestion and you relieve the ailment, Nature herself does the healing by active, normal blood circulation. Why Suffer Needless Pain? If you or some one in your home have a troublesome ail- ment, a lamp like this is a blessing. May be used by anyone. Entirely unlike ultra-violet or X-Ray, tively cannot sunburn or blister. Relieve bronchial trouble, Neuralgia, Neuritis, Sinus trouble, Catarrh, head noises, Asthma, Ear trouble, Rheumatism, Hemorrhoids, Prostatitis, Gall-Bladder, Tonsillitis, Lumbago and many other ailments with soothing Infra-Red Rays. Let Us Send You Our Book on Infra-Red Rays We have an interesting book on the use of Infra-Red Rays which we shall be glad to send free to any reader upon request. Our book quotes leading authorities as well as users of our lamp. Full directions for use, how te order, our home trial offer, etc., are also explained. Infra-Red Rays have brought such wonderful results for others you are sure to be interested. Write today for our book telling more about it. THE WILLIAM CAMPBELL COMPANY 1041 Union Avenue ~-_ Alliance, Ohio There’s No Fun Like Chemistry CRAY a es ~} * ¥ r Have Days of Real Fun Learn the Wonders of Chemistry Anybody can master the science of chemistry with CHEMCRAFT. Work hundreds of amazing and useful chemical experiments; make soap, ink and dyes; test foods, water and soil; produce changes and rform wonderful tricks of che’ cal magic. CHEMCRAFT Is the original and best chemical set; has more chemicals and experiments, Get CHEMCRAFT—then your fun begins! Seven Dandy Outfits to Choose From: No. 1—$1.00 No. 3—$3.50 No. 8—$ 8.00 No. 2—$2.25 No. 5—$5.00 No. 12—$12.00 Laboratory Work Bench $35.00 Sold Wherever Good Toys Are Found Try Chemistry for 2c Free Magazine for Boys CHEMCRAFT Chemist Club Magazine, full of fine seam chemistry interests stories, chemical stunts them. Sent postpaid for only information. Write for your 25 cents. Order it today! Free Copy at once. THE PORTER CHEMICAL COMPANY 115 Summit Ave., Hagerstown, Md. hr | oe “a eee —“ ».4

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—"SaTRASE oo “What Can I Make from a Block?” By Donatp W. Ciark VERY boy at some time or other has held a block of wood in his hand and asked himself: ““Now what can I make out of this old chunk of wood?” Why, hundreds of things! For example, a whole miniature village can be cut easily from blocks of white pine. Small auxiliary parts can be made of bits of wood or heavy cardboard and glued on. The completed buildings can be painted in various colors and given red or green roofs. Then they can be placed in a suitable setting with streets, trees, shrubbery, and accessories. Line off each block in 1-in. squares. Mark with heavier pencil lines just where you intend to begin cutting, and then use a fine saw and a knife to work out the finished forms. In the absence of a fine- tooth wood saw, a hack saw blade can be used, and a keen pocketknife will reach the places where the saw cannot reach. WHITE PINE x3°x4" NEW LINE Steps in blocking out and shaping the houses. Much depends upon painting them neatly. POPULAR SCIENCE MONTHLY 129 PUT THIS WS HOME FREE For!0 Days-No Deposit / A New and Improved Workshop Here is a workshop built to a standard of perfection—accurate in operatiaa most durable in construction—easy to operate. It is absolutely dependable 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- tion. Home workers use it for pleasure and profit. Carpenters use it for making repair parts, spindles, chair legs, cabinets. It is ideal for making all kinds of furniture. The Lowest Price For Such a Sturdy, Complete Workshop MAC, THE PoPULAR MECHANIC, resents the utmost in value a8 oe . Now you can have an accurate, cal workshop at a big sav- ing. Once you use C you will be convinced of its superior qualities. That’s why we want you to fry ét for ten days at our expense. NO A YEAR TO PAY LY TURNS, RIPS, CROSSCUTS, DRILLS, SURFACES, POLISHES, GRINDS, CUTS SCROLLS. A PERFECT. WORK shor ‘ GET DETAILS Quick Rm APPLIANCE CORPO Dept. 220—219 N. Michigan Ave. "wea ICAGO, ILL. IP-ZIP Boys: join a Zip-Zip Shooters’ club everywhere boys are forming these 710) _ clubs, fine sport using this shooter ea which is scientifically and practically made, Zip-Zip Shooter is the best buy we know of for 35c or 3 for $1.00. We will ship to you if your + . f own dealer can’t supply power. Speeds beautifulls throw thes ir Ain : you. wing spread. a ‘4 jong. 41-2 in. carved wood yw Only 25 cents postpa’ U, S. Q AUTOMATIC RUBBER oth Models Guaranteed to Fly or Money Refunded D Co..c bia Special for this month.--Snappy, live ber, 1-8 in. flat, 1-2 cent AS} v4 ~ Columbia, S.C. egg SS a foot; 3-16 in., 1 cent per foot. Postage be extra. ‘ PEEDO MFG. ‘CO., . 5. 253 Albany Ave., Brooklyn, N. Y. Still Greater Bargains in Boice Machines Boice-Crane, the world’s largest builders of small bench machines, now offer you the very greatest bargains in their 14 years’ experience. Fifteen different Boice-Crane Machines. Unsurpassed quality and capacity Seven choices of 2, 3, 4, or 5 machine workshops completely motorized and with individual machines. Pra tical, fully capable, no attachments to change. Astonishingly low priced at $48, $70 and up. f sors fash te remy emmy tn a Be Wee ee as a aaa 4” Handi Jointer 12” Band Saw — Jig Saw Tables 20-inch ground and Table 10x12 inches tilts 45 Table 15x17 inches tilts 45 lished. Planes %x4- deg. Cuts 4%-inch deep. deg. 8-inch saw cuts 2- ee sa on. . Fence tilts 45 deg. Bronze bearings. Copied inch. Elevates for dadoing. Vertical stroke 1% -inch. both ways. Improved rab- after our famous 14-inch Always accurate. Pulley ity 10-inch to frame. between bronze bearings. 6 sizes of, —, y to . § ot Hetee: Seed $12 bet arm. Bronze band saw. Guards, $8. . Attachments for dadoing, bearings. Safety $ Sturdy cdnstruc- guard $3........ 25 tion. Without motor $3 or guards... ing. | r - L pee ‘a ° « Send 10¢ for Boice-Crane’s new Ni Sig gg Fe at $30) (Reais siednepe: Basie $13.50 and up W. B. & J. E. Boice, fare, fore and salon i 4 Dept. P.S.2-E Toledo, Ohio [222 workshops before you buy- © This seal on an advertisement in.POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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NOW! ADJUSTABLE SKe CARBORUNDUM REG.U.S. PAT. OFF. DETECTOR A TURN of the pressure screw gives you perfect tone balance. Then the position is fixed by ad- justing lock nut, so that the pressure remains per- manently sensitive. QJust another improve- ment to further assure the perfect tone quality you al- ways get with the Carbo- rundum Detector—and tone quality is everything. @ Recommended by noted radio-circuit designers. DEALER OR DIRECT $1 .50 in U.S.A. .. Send for Free Book “‘Carborundum in Radio’’ D-6 THE CARBORUNDUM COMPANY NIAGARA FALLS, N. Y. CANADIAN CARBORUNDUM Co., LTD. NIAGARA FALLS, ONT. Carb is the Regi: d Trade Mark of The Carborundum Company for its Silicon Carbide and is its exclusive property POPULAR SCIENCE MONTHLY Tie CARBORUNDUM COMPANY N1aGara Faias, N. Y. Please send me your free Hookup Book en- titled ‘‘Carborundum in Radio’’—D-6. Name si Address Liquefied Helium Boils on Ice and ‘**Freezes’”’ Tin (Continued from page 28) shaft in the air and take the weight off the bearings? Ross V. Gardner, in charge of trade re- search work, has a bushel basket full of such inquiries. For the advertising man he pa- tiently figured out that a silk and rubber balloon ten feet long and as wide and high would be needed for his windmill. He dis- posed, too of the inventor who would put a buoyant helium tank at the front of his: speed- boat to lift it out of the water—and another who proposed to inflate an automobile inner tube with helium and also to use it as a life- preserver to jump from the top of a burning building. The latter had so much confidence in his invention that he proposed to test it himself. Luckily that calamity was averted. GERIOUSLY, one commercially important use for helium has been found in the filling of toy balloons. Beloved of children and adult party-goers alike, the fragile toys are safer from cigarettes and fire when filled with the non-explosive, fireproof gas that has proved so useful in airships. In 1912, just before the world war, only fifteen cubic feet of helium were known to exist. This supply was owned by the cold- temperature pioneer, Professor Onnes, of Leiden, and he valued it at $30,000. Helium was as costly, at that time, as diamonds, black pearls, and pigeon-blood rubies, and rare as radium. Only few scientists had heard of it. But during the war a curious incident is said to have occurred that set nations think- ing. A Royal Flying Corps pilot, flying a pursuit plane, encountered a Zeppelin in the clouds one day in 1917, the story goes. He opened fire with incendiary bullets and watched to see the ship burst into flame—for he knew what happens when hydrogen and incendiary bullets get together. But the Zep didn’t burn, and it kept right on going. Amazed, the pilot returned to his base and reported the mystery. The Germans had a dirigible that incendiary bullets could hit but not fire. Headquarters consulted Sir Richard Threllfall, eminent scientist. Sir Richard replied that undoubtedly the dirigible was inflated with helium gas. There were no more fireproof Zeppelins dur- ing the war, for this single “mystery ship” probably exhausted the last cubic foot of the stuff in Germany. But it started world-wide hints for more of this strange and valuable gas. At THE entry of the United States into the war, the War and Navy Departments called upon the Bureau of Mines to get some helium, at any price. Already the Bureau’s geologists had detected traces of helium in the natural gas of certain Texas wells. They set up the first helium-extraction plant at Fort Worth, and before the war ended 750 cylinders of helium gas were on the wharves at New Orleans ready to be shipped to France for Army observation balloons. But it was not until 1920 that the first helium-filled airship in the United States, the CR-7, took the air. Meanwhile another plant had been erected at Dexter, Kansas, where heliam was found in a curious way. For years the residents of Dexter had been smarting under the banter of their neighbors. In 1903, two drillers digging for oil, had struck a heavy flow of gas at less than 500-foot depth. Local boosters talked of an industrial boom and a celebration was prepared. But when the time came to light the gas, after appropriate oratory, it wouldn’t burn. Visitors from surrounding towns snickered and went home. Their news- papers kidded Dexter wickedly. Later a way was found to light the gas, and use it for fuel, but it was worthless as an illuminant. By chance Prof. H. C. Cady, of the University of Kansas, tested the gas and found that it (Continued on page 131) 1S) This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. February, 1 BethelomBrow; of Your aN Everyone has heard of Tom Brown, leader of the famous Tom Brown’s one of the W%& highest priced musical acts, that has ap- peared allover ~~ the world. If you have not seen them, you have prob. ably heard them play on Victor Records, First-Class Saxophonists make big and the work is easy and pleasant. Yoy might easily become a wizard like. Tom Brown, or a great record- maker like Clyde Doerr or Bennie Krueger or Joseph Smith, $100 to $500 weekly is not unusual for such musicians to earn. Ba. CTrue “Tone Saxophone The many patented improvements, found only on the Buescher, assure a more beau- tiful tone, finer and more a accurate tune and easier it) blowing qualities. Easy to Play— Easy to Pay Because of its many advan- tages, the Buescher Saxo- phone is remarkably easy to master. The rapid prog- ress you make will surprise you. a payments can be arranged, if desired. | 6 Days’ Trial ” Saxophone, Cornet, Trumpet, Trombone or other instrument. Fill out and mail coupon for full infor- mation. Mention instrument ia which you are interested. Buescher Band Instrument Co, 2683 Buescher Block Elkhart, Indiana } BUESCHER BAND INSTRUMENT CO. (aay? 2683 Buescher Block, Elkhart, Ind. i] Gentlemen: Withoutobligating me in any way please send : i I me your free literature. ! 1 aminterested in the t ; following instrument ......cccccccccccccccccccees { DNs oc cccadedskidtédidocsecsensenensaue PPT TrerrrTTrr Tyr rTTTT TTT J én your own home on any Buescher . GEARS All Kinds-Small The most accurate made and prices res, sonable. We carry a complete line of ears in stock for immedia‘ 80 quote on kinds. Send us your inquiries. Write for Catalogue 214 CHICAGO STOCK GEAR WORKS 105 South Jefferson Street Chicage mo ik = > a met eK ‘ ~ ree FEB TO. = p> | —

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© Prob. ards, t. ie >- Tom Clyde Smith, IT such ee i llr : EP a pebruary, 1929 POPULAR SCIENCE MONTHLY IMPROVES Your Radio The HAMMARLUND “Midline’’ Condenser Condensers come and condensers go, but the Hammarlund “‘Midline”’ keeps ahead. Built with watch-like precision and embody- ing every feature demanded of a modern tuning instrument, the Hammarlund “Mid- line” Condenser continues to make radio (Clays cet ao > — of | omen dr woll roducts. Follow Write Dept. PS2 for Folder Hammarlund Manufacturing Co. 424-438 W. 33rd St., New York For Better Radin ammarlund PRECISION PRODUCTS Dust off the Cobwebs BRING out the phonograph and get new thrills from the com- bining of your victrola and radio by means of a Carter Radio-Phono attachment: All the favorites just when you want them. No rewiring necessary—a revelation you'll en- joy. Illustrated folder on request. Write Carter Radio Co., IS) 300 S. Racine Ave., , Chicago, Illinois! TO PICK-UP ano VOLUME CONTROLY, “The Majority’s Choice.” A definite program for getting ahead financially will be found on page four of this issue. Liquefied Helium Boils on Ice and ‘*Freezes’’ Tin (Continued from page 1380) contained nearly two per cent of helium. A 15,000 cubic-foot-a-day plant went up, drills found still richer helium at greater depths, and at the end of 1917 the plant was running. A plant wa: also opened in Canada, where helium had also been discovered in smaller quantities, but was shut down when the war ended. en news came that the Petrolia gas field of Texas, which included the Fort Worth plant and two others, was nearing exhaustion, a hasty search for new fields was made. The result of this is the new plant at Amarillo, Texas, which embodies in its machinery the latest methods of helium extraction developed by the Bureau of Mines. To extract helium from natural gas, the gas is piped from the well into mighty compressors where it is squeezed and then chilled to a temperature of 300 degrees below zero. At this searing cold, everything but the helium turns to liquid. The helium is then drawn off, still a gas, and squeezed again into cylinders or tank cars for transportation to the air field, while the natural gas, actually improved in quality by the helium extraction, is sold for light and fuel as a by-product. Formerly the chilling process had to be performed in several stages, at great expense, but the Bureau of Mines has so perfected the system that the whole process is now a single operation. One of the few remaining difficulties was the transportation of the gas. Formerly it was shipped only in cylinders, of which it took 13,000 to fill the ill-fated Shenandoah at her first inflation. With the co-operation of a great steel concern, a special tank car was devised that consists of three steel tanks forty feet long and nearly five feet in diameter, mounted on a flat base. They contain helium forced in under the crushing pressure of 2,000 pounds to the square inch. Twelve of these carloads will fill the Los Angeles. A final problem was the purification of helium from an airship’s gasbag, contaminated by air filtering through the envelope after a long flight. Three purifying plants have been built by the Bureau of Mines, one of them a mobile plant in a railroad car. A stationary plant, at Scott Field, Ill., can reclaim 10,000 cubic feet of pure helium in an hour. Huge Machine Makes Trick Shots for the Movies | THE latest moving picture technique, the - camera is used much in the same manner as the human eye, seemingly wandering up and down and to the left and right at will. This new technique is responsible for the life-like quality of such scenes as, for example, a per- formance of a trapeze artist in the top of a circus tent, followed by a closeup of a sec- tion of the staring, breathless audience below. How are such sequences made? F. W. Murnau, the German motion picture director, now in this country, in collaboration with experts of a steel company, has perfected the device that makes the “trick-shots” possible. It is a twenty-ton piece of machinery, re- sembling a derrick, with an upright mast in the form of a telescopic piston which can be shortened or lengthened. A horizontal boom also can be increased or decreased at will. To this boom either a platform or cage is fastened, the camera men work. The cage is used when downward “shots” are made. If the platform is employed, the photographers and their equipment are strapped in place, to prevent them being hurled into space by the swift motion of the boom in describing its arcs. The telescopic mast of the device is operated by hydraulic power, while the boom is worked electrically. and it is upon the platform or in the cage that - [Are RING the charging rate automatically. The new on Chargers have added another feature to their many advantages: — Dry—no acids, no water, no corroe sion, no bulbs, no tubes, no noise, no moving parts, high charging rate when the battery is low, low charg- ing rate when the battery is hig The Tapering Charger, 1 Ampere, maximum charging rate is the ideal power supply for the storage bat+ tery. Leave it on all the time, with- out interfering with reception and without injuring the battery. Long life. Instructions and Guarantee printed on container. The 3 Ampere Tapering Charger is ideal for the rapid charging of either radio or automobile batteries. Has all the advantages of a smaller charger. No attention needed — just plug them in and forget them. Elkon Rectifiers are self-healing! They are not affected by accidental overload- ing or line surges! ELKORN Replacement Rectifiers This exclusive feature of the Elkon Rectifiersissaving customers millions of dollars! After a long time—5000 hours for battery chargers—a year or so for “A” Eliminators, renewing the rectifier will prove to be an economy. The old rectifier may be slipped out and the new one put in—only a min- ute required—and the unit is as good as new. If you have a power unit using a dry sontiee, ask soe dealer about the Elkon Replacement Units. Remem- ber Elkon is the only unit authorized by Fansteel to replace the acid jars in the Balkite power units. Division of . R. Mallory & Co., Inc. ek 5 3. Ave. “A New York City @ This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. ELKON, INC., ‘ Dept. E-12, 350 Madison Ave., New York City Send me complete information on the Elkon Radio Products. Name Address

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132 Make big money from repair work 10

Practically every householder spends at least $10.00 to $50.00 each year and many spend several _ times that much on simple repairs that can be male quickly, easily and well with SMOOTH-ON No. 1 With a can of Smooth-On you can save this money in your own. home — and by doing similar repair work for others, you can

Band” SMOOTH-ON

make money. Band for swoom "ON * No skill is re into leak quired to make Leak at radiater joint repairs and the stopped with Smooth-On amount of Smooth-On used on any one job seldom costs more than a few cents. Typical repairs that can be made per- fectly with Smooth-On:—Stopping leaks in steam, water, gas, oil or stove pipes, mending cracks, breaks or leaks in furnaces and _ boilers, radiators, tanks, sinks, pots and pails, making loose handles tight on um- brellas, knives, hammers, brushes, drawers, etc., tightening loose screws, hooks, locks, door knobs, ete. On the Automobile:—Making cracked water jackets and pumps good as new, stopping eaks in radiator, hose connections, gas tank and gas, oil and exhaust lines, mak- ing a fume-proof joint between exhaust pipe and tonneau heater, tightening loose head- light posts, keeping grease cups, hub caps, and nuts from loosening and falling off, etc. To get perfect results, write to us for and use the Smooth-On Repair Book. Free if you re- turn the coupon. Get Smooth-On No. 1 in 7-0z., 1-lb. or 5-lb. tins at any hardware store or if necessary direct from c<___ SS} Smooth-On Mfg. Co. ‘Dept 37, 574 Communipaw Ave. JERSEY CITY, N. J.

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POPULAR SCIENCE MONTHLY

Men and Ideas Setting the Pace in Aviation (Continued from page 41) craft could escape the novel gun’s peppering. Its mechanism moves the barrel to weave a regular pattern of fire, automatically, in a way that gives it the covering power of a shotgun instead of a rifle. An adjustment adapts it for long or short range. Tests of the device are planned by the Army Air Corps at Wright Field, Dayton, O. Fights Fire in the Air HAT is said to be the only automatic fire extinguisher for planes has recently been introduced by an American plane-building firm. The device, a European invention, con- sists of a central chemical tank from which seven pipes terminate in nozzles at strategic points particularly subject to fire. Should a blaze start, the nozzles immediately could loose a high pressure spray to extinguish it. **Prop”’ Blades Made Hollow Goi propeller blades may go out of style if six new experimental models recently ordered by the Navy prove successful. The new blades, of chrome vanadium steel, are hollow. They are said to be the first of this type that can withstand the strains of a high- speed airplane. Besides being light in weight, the odd air screws are ecoriomical to build. A recently-invented arc welding process joins two halves to make the finished propeller. Hops from Train—Crash ! CHICAGO pilot tried to take off, in his plane, from the roof of a speeding railroad train the other day. His plane was wrecked but the flyer escaped unhurt. Eddie Ballough, the commercial pilot who made the try, was seeking to show the possi- bility of dispatching air mail from a moving train. His diminutive Monocoupe machine was secured to the top of an Illinois Central train outbound from Chicago. When the train was making sixty miles an hour a cross current lifted one wing and the plane went out of con- trol and crashed upon the northbound tracks. Ballough crawled out of the smashed cockpit with only a scratched knee to show for the mishap. ** Aerial Fish Express”’ AN INTERNATIONAL “aerial fish ex- press” is soon to be established between Mexico and the United States, according to a Mexican government official Refrigerator airplanes are to rush cargoes of perishable sea food between Laguna Madre, Mexico, and Houston, Texas. The novel project is backed by Houston business men, who have purchased planes for the service. Duration Record Stands RECOGNITION by the U. S. branch of the “F. A. 1,” world aero governing body, makes official the new American duration record of fifty-nine hours in the air, set not long ago by the round-the-world aviators William Brock and Edward Schlee. The world’s record is held by Germans. Even Ice Cream by Air Mail Two quarts of ice cream recently traveled from Utica, N. Y., to Texas via air mail, to be eaten there next day. With the container, the bundle weighed twelve pounds and bore $18.50 in air mail stamps. Hundred-mile-an-hour mail delivery has sped other odd items on their way; everything from bread to pawn tickets and jewelry.

rain SALTER RALEIGH |: ge

“Who Disc OVC1E LH j a Good a Pine Gan Be” =

’ . < . Wi. milder than what you've been smoking. Milder, and mellower, and for two perfectly good reasons: it’s choice leaf and it's aged more carefully in the warehouse. Result, Sir Walter’s favorite smoking mixture has so much genuine distinction of flavor and fragrance that sophisticated pipe smokers are prompt to recognize it and grow enthusiastic. Y LIMITED OFFER t (for the United States only) If your favorite tobacconist does not carry Sir Walter Raleigh, send us his name and address. In return for this courtesy, we’ il be delighted to send you without charge a full-size tin of this milder pipe mixture. Dept. 183 Brown and Williamson Tobacco Corporation k Winston-Silem, North Carolina t

raepecr SIR WALTER RALEIGH Who discovered how good a pipe can be

It’s milder

aa

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ry, 19% RFRA F608. Z pebruary, 1929 BS cepecting for Gold with Electricity (Continued from page 26) t radio direction-finder to trace the under- 4° currents’ path by their magnetic effect in the air. The leapfrog method consisted of laying wires on the ground side by side, taking elec- tric measurements, and then lifting or “‘leap- ing” one wire over the others and repeat- ing the readings. — In another experiment the prospectors found that they could use the current of three or- dinary radio “B” batteries, hitched together, in place of the telegraph transmitter. Dial- reading electric instruments, instead of head- phones, then measured the currents’ path. Magnetism, radio, and seismic shocks are some of the other fascinating new treasure- finding aids lumped together under the title of “geophysical prospecting.” A few ores, notably the magnetite, are mag- netic. Like the lodestone of ancient mariners, which was simply a piece of magnetized iron ore, they deflect a compass needle near by, and play tricks with a more distant, but more sensitive, electromagnetic detector, such as a modern “ magnetometer.” Wile the Bureau of Mines experts were using electric instruments to survey the Caribou Mountain magnetite deposit, two experts of the Colorado School of Mines, Dr. C. A. Heiland and J. A. Malkovsky, surveyed it with a magnetometer, by taking advantage of its magnetic properties. A highly accurate map resulted that checked closely with the electric survey and the original Geologic Survey map. Amazing mineral “‘finds” of gold and other precious substances have been reported by the use of radio waves. Radio waves, directed into the earth and striking an ore body, are said to cause the buried metal to rebroadcast a new radio wave, through which its location may be detected—much as a local radio station rebroadcasts, on a different wave, a program received faintly from a distant station. Sul- phide ores such as those of iron, copper, zinc, and silver are described as peculiarly sus- ceptible to discovery by radio apparatus. Experiments by the Bureau of Mines in a Caribou Mine Shaft to find whether radio waves would penetrate rock to any great dis- tance showed that with a super-heterodyne radio receiver signals from above the earth could be detected at least 500 feet underground. So successful has prospecting for oil with artificial earthquakes proved that several great oil companies are using it extensively, particularly in the San Joaquin valley in California. By measuring the speed with which earthquake waves from dynamite blasts travel through the earth, observers can tell whether underground domes of salt, which are often associated with oil pools, occur in the vicinity. The depth of a layer of possible oil- producing shale is also indicated. Seismographs or earthquake detectors are used. These record the tremors on photographic film. In one recent method, which substitutes blasting gelatin for dynamite, a row of charges is shot off and the time of the shock’s arrival indicates the depth of the underlying shale. Usually radio flashes time the earthquake wave’s speed. But this is not all. Actually weighing a por- tion of the earth’s crust, to detect oil or ore veins beneath, is possible with an extremely sensitive weighing device known as the Eotvos nce. Because oil is lighter, and metal heavier, than the earth, the difference registers on the delicate instrument. Of course it can- not weigh directly, but resembles instead the device recently used by Dr. Paul Heyl, of the U. S. Bureau of Standards, to weigh the entire earth. Used for prospecting, it indicates the density of a portion of the earth crust. of Nebraska . POPULAR SCIENCE MONTHLY 133 WE PAY FREIGHT ' 6 ROOMS “a PORCH BATH IN- CLUDED a oe ag SEs - we ye iene’ pes NO EXTRA CHARGES Buy At Wholesale! Y OU can get all materials direct from mill and make 4 big savings + on your home! Owners tell of $200 to $1,500 actual savings on single homes. Mill-cut lumber saves you 40% labor. Not portable. Sturdy, substantial, permanent homes. Guaranteed materials delivered to your station freight paid. Most remarkable money- saving prices ever offered. “Saved $1,000 on House and Garage’’ says Mrs. Coombs, “counting labor and lumber. All is as you said. I have advised my brother to order one of your ; “Believe I saved $500 by buying from you,” writes B. A. Anderson . . Mr. Davis saved “between $1,000 and $1,500” on his home. You can do as well. Every home owner who built a Liberty saved money. FREE HANDSOME BIG HOMES—FULL COLOR---WRITE Get beautiful big book of newest AMAZING NEW PLAN Wesendyoucomplete materials. You send us no money. Inspect quality and quantity on your own lot for 5 days. You do not pay one penny for materi- als unless completely satisfied. Is there any better proof of the confidence we have in Liberty Homes? 32 years’ square deal- ing behind our Guar- antee. Send coupon for Big New Book of Homes today. homes. Page after page of homes in full color. Amazing values from $379 to $1483. 37 home plans— wonderful 4 to 7-room bungalows. 1% and 2-story homes. American, Dutch, Colonial, English designs. Practical—beautiful. Book shows table of construction time for each home. Also garages, letters from home owners, actual practical facts and figures to save you money. 32 years of square dealing behind our uarantee. Write or send coupon or free book today. You'll save yourself a substantial sum. Address LIBERTY HOMES Lewis Manufacturing Co. Dept. 132, Bay City, Mich. PRICE INCLUDES all highest quality lumber cut-to-fit, doors, win- dows, stairs, high grade interior woodwork, lath, shingles, hardware, glass, paints, nails, etc., com- plete. Working plans, instructions, FREE. Time payments may be arranged if desired. All materials fully guaran- teed. Freight paid east of Mississippi River and north of Mason-Dixon line, also to Minnesota, Iowa, Missouri. SEND FOR BOOK homes”. . BOOK OF LEWIS MFG. CO. Dept. 132, Bay City, Mich. Please send me, ‘FREE, your Book of Liberty Homes illustrated in color. PORTA © (MOTOR DRIVEN ) $13? only 4 Never before and never again w! to purchase a genuine power saw at such a price — time only.) D ALE SAWS ill you be able uaranteed | portable rect drive — no gears. Fastest saw on the ~~ Light an an precision by machine tool il jive up back- breaking costly handsaw- ing. by taking advantage of this amazing offer.Pays for itself. Your choice for only $48.00, Money re- funded if not satisfactory, within ten days. ay 7 ~ 2000 - Syracuse, N.Y. © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INST'TUTE OF STANDARDS. See page 8. Get Into a Band; Try aConn FREE! yx can take your place in a band almost immediately. Conn easy-playing instru- ments and the newinstruction met enable anyone who can whistle to play tunes in the very first lessons. 7 “Payments on any Conn instru- P mnt for bod or orcheetra Send Yor free litera- ture and details of trial offer; men’ C.G.Conn, Lid. 232 Conn Bldg. Elkhart,Ind. ONN AND INSTRUMENTS |

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134 Justice of Peace Smokes 8395 Tins of Same Tobacco Remains true to his favorite brand for twenty-three years TF any man be a sound judge of what’s right and what’s wrong, it’s Justice of the Peace Bostock. And no exceptions taken on pipe-tobaccos or any other de- cisions that may be handed down in the county court-house. For twenty-three years this gentleman has rende opinions favoring just one brand of tobacco—Edgeworth. He says he’s smoked more than eight thousand tins of it! Which certainly places him high among the long-time smokers in the Edge- worth Club. Ipswich, S. D. Sept. 4th, 1928 Larus & Bro. Co., Richmond, Va. Gentlemen: In answer to the challenge of J. J. Roberts of Columbia, 8S. D., as printed in the Minneapolis Journal dat Sunday, September 2, I have smoked Edgeworth for twenty-three (23) years, and for two years previous to that time I smoked Qboid, which, I believe, is manufactured by your firm. During this time I have smoked at least one can each day, and to verify this state- ment you may address the C & C Cafe of this city, where make my tobacco purchases. It may be interesting to know that my urchases of Edgeworth during this period ave totalled more than 95 (eight thousand three hundred ninety-five) cans, representing a total expenditure of more than $1259 (twelve hundred fifty-nine dollars). I have never smoked any other brand ef tobacco but Edgeworth during the twenty-three years. Yours very truly, (signed) Chas. Bostock Justice of the Peace Any man who stays with one brand of pipe tobacco for twenty-three years must have a pretty good reason—and in the case of Edgeworth it doubtless is because Edgeworth never varies. Personal: To those Tage are See tried worth, we make this offer: Let us send you free samples of worth so that _ may put it to the pipe-test. Simply write your name and address to Lar- us & Brother Company, 10 S. 2ist Street, Richmond, Va. If you like these trial _ helpings you'll find tins of Edgeworth ; a of the same lik- able quality on sale at all tobacco stores. Edgeworth Ready-Rubbed comes ready for your pipe. worth Plug Slice is for pi smokers wine ike to “rub-up” a pipeful in the palm. Both ked in pocket-size “gaan in pound humidor tins and also several handy in-between sizes. On vadio~ tune inon WRV A,Richmond,Va. —the Edgeworth aior Wi me 270 F i110 ies.—Special F meters. F: —, ‘ea- ture: The “Edgeworth Club” Wednes- day evening at nine o’clock,Eastern Time. POPULAR SCIENCE MONTHLY Marvels of Plane Design (Continued from page 54) body; it has almost all been absorbed inté enor- mously thick wings. All these ideas may help, and perhaps it is just as well that airplane de- signs continue to be as diversified as they are today until all the promising designs have been tried. . Another way to improve the load-carrying ability of planes is to increase their power by cutting out air resistance. Landing gears, for instance, are very necessary for taking off and landing but are a nuisance in the air. Some idea of the terrific toll they take in power may be imagined from the fact that eat eotelas two spoked wheels, 26 by 4, with cloth cuts their twenty-eight-pound air resistance in half. And the fourteen pounds saved would enable a plane to carry 120 pounds more fuel with the same power expenditure. But suppose the whole gear, wheels, struts and all, could be tucked away in the machine’s body as a bird folds its legs in flight! It sounds simple, and undoubtedly will be done in time. But mighty few designers have succeeded in producing an amply strong structure that will unfold in- fallibly when it should. Rather than chance wrecking a machine, they have turred instead to bringing their craft out of the early “bird cage era” by eliminating stray wires. MORE efficient wing sections—a wing sec- tion is what one would see if the wing were sawed through in the direction of flight— help cut down power consumption. Lately Dr. Max Munk, of the National Advisory Com- mittee’s staff, has worked out astonishingly successful wing sections which, his associates believe, go a long way toward solution of the problem. But though the finished airplane may be the last word in efficiency as to power and lift, it is useless unless its controls are infallible. Through some one’s blunder, one of the new British fighting machines developed during the war could not make a right turn except by skid- ding—like skidding in a motor car. A British war pilot has recorded how a squadron of these machines met a German squadron and exe- cuted a skidded right turn. The Germans thought they were being “kidded,” where- upon the whole Maltese-crossed squadron promptly looped the loop. After the disastrous fight that ensued, pilots of the surviving British craft speedily put their skidding machines out of commission in numerous “accidents” that may not have happened solely by chance. Fortunately new airplane designs appeared on the front about every eleven weeks. EVEN in standard aircraft models, pilots occasionally report “dead spots” in the controls, which, in certain positions of the ‘omy have no effect at all. Recent studies ve shown ways to combat the defect, but probably the pilot will always have to be men- tally alert. When a machine stands on one wing tip, for instance, rudder and elevator take over each other’s duties. Reactions to such one must be mare & oy “y- ost persons imagine that a low speed-— meaning about thirty miles an hour—is de- sirable for landing. True, a pilot grounding his plane at sixty miles an hour, the landing speed of some fast machines, has only one second in which to recognize o ions eighty-eight feet ahead. But it is obvious, ever to a novice, that a machine traveling fast v hen it lands is likely to be a shorter time within a particular zone of turbulent air than a slow- moving craft. At low speeds control of a plane is very small, for all practical purposes. But at high speed a — control “grips’”’ the air, a fact that can verified simply by swinging about a piece of cardboard in the hand. Comfort in the air is another good reason for fast landing and flying (Continued on page 135) ges 0d rest partertes as Actual Size Pain is Nature’s warning — don’t — it. Such troubles as Arthritis, Rheumatism, tarrh, Neu- ritis, Anemia, Lumbago, Backache, Run Down Con dition and other diseases caused by impure blood— or any congestion—will be quickly relieved. Campbell’s Magnetic Health Pad when attached to an electric light outlet becomes a magnetand netizes the iron in your blood, making it able to al sorb more oxygen which is a life-giving ‘essential to health. It Seems Like —but it isn’t! It is simply Nature’s way of purifying the blood. No drugs, no electricity touches you, Nature’s way of starting the red corpuscles to work by supplying them with more oxygen from the air, Let Us Send You Full Infor- mation—FREE Write for free folder on Campbell’s Magnetic Health Pad and tell us your trouble. It gives full description, instructions for use, order, etc. Also explains 30-day free trial. Get my special introductory offer, Uneven volta ils radio Glow amd sulee cubes. AMPERITE -10 r0tth mount, adjusts itself to the exact n in U.S.A.) © hh tube. A type for every eK FA, tube — A.C. or D.C. © Rstialt Companys _ QUYRANKLN sr. © > This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. cae 5 N

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arvels of Plane Design (Continued from page 184) A machine that lands at low speed is in the air. Bumps in the air become in- ifed with slow cruising. A plane with a top speed of fifty miles an hour would shake its — black and blue on a bumpy day.

machines today are standardized to the extent that they have usually one body, a big wing or two in front, and a little one behind. No one knows what would happen if the rear wing were made as big as the front one. There js some experimental evidence on the subject which is not conclusive, and power-driven machines of this type have so far proved un- fortunate. Another novel departure, the verti- eal flying “helicopter’’ of popular dreams, like- wise awaits further development. One English jnventor has spent more than $250,000 in iments with the helicopter, while an American inventor has likewise invested great gums. Their success, though measurable, has | been small. IRPLANE experimentation is one of the Kf ‘costliest things on earth, and it is this cost ithat keeps designers cautiously following in each other’s footsteps. Formerly a new pro- duction, still in its experimental stage, would be taken from the factory and turned over to a test pilot. If the man liked the machine it would be put into production. This threw the whole decision upon the test pilot, and, being human, he was likely to make a mistake. So far the most successful way of testing a new design is to construct a small model, fix it in a “wind tunnel” on suitable scales, and turn a high wind against it. Because the mod- els are very small they must be accurately made if the result is to be reliable. This ac- curacy means costly hand work. If a complete wind tunnel -test is run on a new design, the cost is likely to be about $1000. But by com- bining a wind tunnel test on a model, and tests with strain-recording instruments on the fin- ished plane, a very complete check on the de- sign is possible. Even so, designing a plane will remain an art, rather than a science, until the whole thing can be done mathematically. No airplane could leave the ground, no matter how perfect its design, without a motor that is a masterpiece of engineering for its com- bined lightness, economy of fuel, and power. While an automobile used in city driving may burn up from a pound and a half to two pounds of gasoline each hour for every horsepower that | it develops, a modern airplane engine will per- form consistently on about half a pound per horsepower hour. Even a plane with a 200- horsepower motor, despite popular opinion, is economical to run; a modern machine so pow- ered makes eight to ten miles on a gallon of gasoline. a = would think, after seeing the heavy cast iron of automobile engines, that a cylinder wall barely 14 of an inch thick is strong enough for an airplane motor that must bear far higher strains? Yet hundreds of air- plane pistons dance tirelessly on their limited path, separated from the outside air only by such a narrow margin of metal. During the war an engine that would run more than seventy hours between overhauls was considered a good one. Now there are motors that run as long as 400 hours before a -| general overhaul is required. No more strik- ing excerpt from the fascinating story of the airplane engine’s development could be found than the evolution of the air-cooled motor. Only a few years ago it was thought impos- sible to design a really satisfactory air-cooled motor of more than 100 horsepower. Then came a period of study and testing. Heads were screwed on, bolted on; and shrunk on. Valves made of uncommon alloys were tried. One material after another was made into cylinders and tested to (Continued on page 136)

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“Standard of the World” A Fitting Title for VICTOREEN Super Receivers Down thru the years, from the very beginning of Radio, Victoreen has kept ahead of its time. Developments from the Victoreen Laboratories are con- stantly advance announcements of radi- cal improvements in radio reception. - The New Victoreen Circuit for 1929 eclipses all past achievements. It com- bines unsurpassed -sensitivity, selec- tivity and tone quality. Perfected A. C. Operation Until you have heard and used a 1929 A. C. Victoreen you cannot realize what a wonderful receiver it is. Stations that you have never heard before, together with all the old favorites, are at your in- stant command. The heart of this master circuit is the Victoreen Super Transformer, vastly improved for 1929, tuned and matched to a precision of 14 of one per cent. In addition, the Victoreen Circuit contains improvements far ahead of its time. Complete Kits Available Either A. C. or D.C. Write us for complete information re- garding the latest Victoreen develop- men ts. Blue Prints and A bly instructions are FREE, State ay ye you wish A. C. or Victoreen Power Amplifier & “B” Supply makes any good set better Supplies 45, 90, 180 and 450 volts, using a UX 210 or 250 in the last stage. Contains two volt- age regulator tubes so that the 90 and 180 volt taps are paeme with a constant volt potential. word in “B” supply. For the ory you must have it. Free Blue Print, with list of parts and com- plete assembly instructions, will be sent upon » Fequest. THE GEO. W. WALKER CO. Merchandisers of Victoreen Radio Products 2825 Chester Ave., Cleveland, Ohio. Victotreen Quality Radio Parts POPULAR SCIENCE MONTHLY Marvels of Plane Design (Continued from page 135) destruction. Finally Government engineers developed a cylinder with a cast aluminum head screwed and shrunk to a steel barrel. From that point came our successful trans- ocean flights. Soon it is expected that engines cooled directly by air and developing more than 500 horsepower will be on the market. Hew about water-cooled engines? Author- ities estimate variously that from a third to nine-tenths of all engine failures are caused by “plumbing”—that is, gasoline and oil lines, and, in water-cooled motors, the radiator, water pump, and connections. Eliminating the troublesome water-holding parts spells a great advance in reliability, although at the expense of some increase in head resistance and vibration. The very problem of choosing be- tween two systems, air and water ccoling, is only another attraction of airplane work. The answer must come from the designer’s brain. 1 COMMERCIAL freight work, one engine is more economical than any possible arrange- ment of two or three. Also, some operators feel strongly that one engine run a third under full load is more reliable than two smaller engines at full load. This feeling is not reciprocated by the public, and in passenger work it is ve likely that three engines will have the call. Safety is of paramount importance. There is still another possibility—no motor at all. So far it has been necessary to launch motorless airplanes, known as gliders, from a hill, or in a high wind. Some engineers stoutly maintain that man will eventually travel from place to place, in these craft, with the speed of an express train. The power will be secured from the wind. There is small likelihood, thouzh, that anyone now more than ten years old will ever pilot one of these planes. But there are other motors besides those that burn gasoline. How about electric motors, steam engines, or internal combustion engines of the oil-burning, Diesel type? ONE of the lightest electric motors ever built weighed seven and a half pounds per horse- power—more than three times as much as our present gasoline motors. In fact, one of the newest aero motors is said to weigh only a pound and a half per horsepower. In extremely long flights electric motors might be valuable, dispensing with great loads of gasoline; for local work the only advantage might be relia- bility. And this assumes the practical realiza- tion of power transmission by wireless; for of course a plane could carry no wires. As for steam engines, the same objection of excessive weight per horsepower applies. A typical mechanical-drive turbine that weighs 4,000 pounds may develop from thirty to five hundred horsepower, depending on steam con- ditions—the top figure showing only one horse- power for every eight pounds of weight. An- other serious objection to steam engines for airplanes is their inefficiency. Water-jacketed boiler walls and economizers galore bring the fuel-conserving efficiency of one of the finest steam-electric plants in the country to what is considered the extraordinary figure of twenty- four and a half percent. Compared with this we find efficiencies of twenty-five percent com- mon for gasoline airplane motors, and at least one tested at thirty-one percent. In the field of safety there is the promising heavy-oil engine emery An the near future. With this power plant fliers can carry some- thing approaching crude oil for fuel instead of highly inflammable gasoline, and perhaps dispense with troublesome ignition systems. All this experimental work is very costly and slow, so that future work is likely to result in refinement of design rather than in anything startling. A firm foundation is now laid in aeronautical construction. The future will bring forth greater safety and efficiency. According to a recent article by the president of the world’s largest motor fesearch corporation, there is enough energy in a gallon of gasoline if con- verted 100% in mechanical energy to run a four cylinder car 450 miles. INVENTION ASTONISHES A marvelous device, already installed on thousands of cars, has accomplish- ed wonders in utilizing a portion of this waste energy and is producing mileage tests that seem unbelievable, FREE SAMPLE and $100 a Week To obtain national distribution appointed everywhere to help supply the mand. to E. Oliver, money making offer. 999.820 -E. Third St., Model Airplanes THAT FLY Set No. 1, Only — + Great Fun. Learn Howto — | Make and Fly Airplanes BOYS—at last, here is a genuine alumi plane that really flies. And at a small price oe ae he “‘Mocar”’ monoplane—Set No. 1—is a copy of J bergh’s famous Spirit of St. Louis. Wing spread 18 int fuselage 12 inches, powerful motor, spec Dropeller ber tired disc wheels. Weight complete only about Qh This is a practical, simple, real model plane that gives * a whole lot of fun at a very moderate cost. Theall construction makes a sturdy plane that will stand 8 lot of abuse. The outfit is mounted on cardboard with all plainly marked and full instruction for assemb' Pie only tool necessary. Construction Set No. 1. Connie with rivets, bolts, disc wheels, wing and fuselage eoy. ering material, only $1.50 postpaid G for $4.00). Moda L made up ready to fly $2.25 (3 for $6.00) postpaid, Order now or see your dealer. A -\} | The Mount Carmel Mfg. Co, Dept. S New Haven, Miles --_-/ fae tm ofGas/ NEW GAS SAVING CAR OWNERS Not only does it save gasoline, but it also creates more power, gives instant starting, quick pick-up, and eliminates carb quickly, men are being the tremendous de Free samples furnished to workers. Write Pres., for this free sample and or WHIRLWIND MFG. CO. Milwaukee, Wise, A definite program for getting ahead financially will be found on page four of this issue © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. 24a. = ee o>

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or Ss thal] Zetes reek & by) zz a F 35a? | ~—— ae Pot 3 ii: | F pebruary, 1929 Two Outstanding Already Raytheon has brought television tubes past the “‘any- thing that works”’ stage toa point where reliability and long life are added to practicability. The Ray- theon Kino-Lamp is the long-life television receiving tube— adapted to all systems and made in numerous types. List Price, $7.50 ‘ {Rayt eon & rowel £ Again, in this sending tube, Raytheon has developed plus-service through long experimentation and research. The Foto- ll comes in either hard-vacuum or gas- filled types, and in two sizes of each. Information and prices upon application Write usf or further information regarding Raytheon Television Tubes RAYTHEON MFG. CO. CAMBRIDGE, MASS. POPULAR SCIENCE MONTHLY Washington and Lincoln. _| , Both Were Inventors (Continued from page 23) of the boat was over the dam and was so pointed down that the water got in and sank the craft lower and lower. Things looked bad. A load of pork barrels began to slip toward the sinking end. People from the town came out to enjoy the excitement. But to Lincoln it was no holiday. All day he worked there, trying to scheme out a method to save the boat. At last he hired another boat, brought it up as close as he could, and unloaded the pork barrels into it. Then, getting an auger, he bored a hole in the bottom of his own boat, and invited the people to come on and help weight down the other end. The water began to drain out, and the boat was saved. “That young feller, he’s got ideas,” the crowd said. Safely over the dam, Lincoln plugged up the hole and got the boat to New Orleans. But the experience made a deep impression. ‘ime passed, and the former river boatman went into politics and was elected to Congress. Once, returning home from Wash- ington by way of Niagara Falls, he was pro- ceeding on by boat through Lake Erie. And what should happen but the very thing which had happened when he was a boatman on the way to New Orleans. The boat stuck. The captain had faced that problem before. He piped all hands out and ordered them to | take all the barrels which could be found aboard and to force them under the side of the ship below the water line. Imagine the shout- ing and hullabaloo that went on as this was done by the rough deck hands of the day! And then, slowly but surely, the boat began to rise. And as it rose Lincoln stood at the rail watching intently. This was his own language, something he knew about. Seventeen years ago he had wrestled with the same difficulty. Taking a piece of paper from his pocket, Lincoln sat down, placed it on top of his high hat, and begen to make some sketches. “I think maybe I’ve got an idea,” he said. When he returned to Springfield he went to see a mechanic who had a shop near Lin- coln’s law office. The man loaned Lincoln his tools and Lincoln began to work out his inven- tion in the man’s shop. The idea of it was that, by means of a bellows, air could be forced under the ship to lift it free from its difficulty. HE USED the tools, but much of the device he whittled out by himself. Contrast the different methods employed by Washington and Lincoln. When Washington had an idea for an invention he could have his own smith do the work for him. Lincoln had to do his own. Lincoln began to whittle at the model, but also he had to keep his law office going, and so he took it to his office and sometimes would do some of the whittling between clients. At last, the model was finished. It was about twenty inches long. He gave it a rather long and impressive name—*‘ An Improved Method for Lifting Vessels Over Shoals.” He sent it to Washington and applied for a patent. It was granted by the issuance of Number 6,469, and Lincoln was really and actually an inventor. The model he built can be seen today in the Patent Office in Washington. But Washington was a more practical man in this respect than Lincoln was, for Washing- ton’s inventions were used, while Lincoln’s wasn’t. Like Washington, Lincoln had an interest in mechanics, but his interest was that of a lawyer. Once he delivered a lecture which he called the “‘ Age of Different Inventions.” He liked to talk and philosophize about inven- tions, while Washingon was interested in getting out and making an invention work. IS] This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. Clear Silver microphone to you SS workmanship, correct design and the careful selection and testing of all materials are re- sponsible for the great popularity of CeCo tubes, You’ ll find a CeCo tube will last longer, perform better and give you more genuine enjoyment from your set, There is a CeCo tube for every need and they cost no more. They are the best engineered tube in the industry. Sold everywhere. CeCo Mfg. Co., Inc. + Providence, R. 5. © Radio Tubes

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POPULAR SCIENCE MONTHLY Advertising GET Into ao tg soure meaty 2 at home, Ex- Derience unnecessa “established o text i ured. Practical werk. Old est. paed oe school. wme and address for interesting avis School of Advertising, Dept. sae 360i Mi gm, Chicago. Advertising Services 24 WORDS, wo rural Westies, $6.04. Ad-Meyer, Rates 40 Cents a Word. A 10% discount is allowed on all contracts for six consecutive inser- tions. Advertisements intended for the April, 1929, issue should be received by February 5th. Submit details of proposition with order. Books and Periodicals WHAT the Radio ew od should know—a 24-page booklet with full information on selecting and operating. Price 25 cents. Popular Science Institute, 246 Fourt Ave., New York. Education and Instruction — 7 — 2 — — Service examinations without seeing our free ca i co bian Corte spondence College, Washington, — USED correspondence courses >a Toa ag sold. Trifling fee. Home Study Circle Detroit. 3961 constield, ag Entry Bookkeopin ping mastered 60 hours with keys; 30 days. anteed. International eaten Spring field, », Doma ee a Electricity 4112P Hartford, St. Louis, Mo t be without the im- facts on M Making. sr een® socey Se Se Action vertising Rate Folder" whi h contains Palo Action averting if'you are anxious for qulek a pa Co,, Auburn, Mass. Send 5 4TH EDITION Revised and down to date. “Radio Theory and Operating,”” by Mary Texanna Loomis. The standard radio text and reference book of America. 992 es, over 800 illustrations, flexible binding. Price, postage paid. For sale by hundreds of book dealers Mhroughout America and many foreign countries. Or may be purchased direct from the publishers. Send check or mohey order to Loomis Publishing Company, Dept. 22, Washington, D. C. THE Electrician’s Wiring Manual, By F. Seng- stock, E. E. Contains all the information BA “tor the preoes installation of lighting and power systems ouses and other buildings. " completely covers inside electrical wi and construction accordance with the National Electric Code. Pocket size—flexible bind- 448 pp. Price $2.50. Popular Science Monthly, ) Fourth Ave. .. New York City. eeenogos se a ELECTRICITY easily learned from H trated Electrical Guides. Write for Free Tien Question Book. Audel—65 W. 23d St., New York. af Engines— Motors—Dynamos MAKE Electric Motors—half and one e horse-power, 4. © gy motor Rig “—— > show Ww connections 8 rn ck, easy. t aines Brog, Gainesville, Texas = ~ tos Motors Reconditioned ual Money bec A.C. or D.C. % HP. smi atx THe. » $24.00, 2 H.P. $30.00. Others tg a a a a den us a yA Problems. Tomes Brothers otor Company, One ar ve. lendal Island, N. Y. ~ Business Sen nll li Farms and Farm Lands ‘ard Hol” awvonder boa avi n—3 2a ee , fame fortune! ‘Sent { tree... Ee ra o. Theatre Bidg., LEARN the 2 business. juick results. 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Write today for a ne ee of me otic -Action —— Rate Folder’ sh You Can Use Popular Science Monthl Frotteably. ” Address your inqu ry to: Manager, Classified Advertis- es. Feoular Science Monthly, 250 Fourth Ave., New ork. District Managers Wanted WE START you ina Yee og business -of your own, $100 to $200 weekly - —_ without capital or can- vassing, no agency. New introduction plan. District managers, men or women for new facial massage instru- ment; enormous d = profits; few dollars for uipment starts you. 8, write quick Massaway Com For particular: pany, 687-F Boylston St., Boston, Mass, GET quick cash sale for your property an Details free. Write Fisher Agent. Hannibal, araere Field Glasses ose tee Field ages. $3 to $85. Alden Loring, Dept, M-2, O-we-go, N. - YU For Electricians and Helpers THE Electrician's Wiring Manual, By F. E, stock, E. E. Contains all the information needed 10 ing. 448 pp. Price’ 250 Fourth Ave., New York City. For Inventors UNPATENTED Ideas Can be Sold. I tell you and help you mike the sale. Free particulars yd hted). Write W. T. Greene, 805 Baltic Building, ashington, D. C. INVENTIONS Commercialized. Patented or ue patented. Write Adam Fisher Mfg. Co., 183 Enright, 8, is, Mo. INVENTORS’ Universal Educator—contains 900 mechanical movements; 50 perpetual motions. Tells how to obtain and sell patents. Suggests new ideas, Explains how to select ty} attorney and avoid sharks. Special Price, $1.00 postpaid. Albert E. ich, 681 Ouray Bldg., Washington, D. C. IMPORTANT to advertisers! Are you deriving prof from ne ur advertising? Write today for a copy ti “Quic si Agrerma Rate Folder’’ show ‘Hoe You Can — ience Monthly Profitably® Address K., our ing ry to: Manager, Classified Advert! ing. Dl lence. “Month y, 244 Fourth ines ew Yor INVENTIONS Developed and Commercialized, Frank G. 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Ua I ink! | EE of Fy | lB “ueal fibgs se: a F peel? al 3 fret E 3 peel BE! ll BeoSes; =F] PRAES! Fes! || February, 1929 MONEY MAKING OPPORTUNITIES SECTION Pick the RADIO JOB 143 you want and fill it in Radio Operator $90 to $200 per month with all expenses paid Broadcast Operator $1,800 to $4,800 a year Way struggle along on less than $45 a week? Why wait years for success that can be yours in only 9 months? As a result of a marvelous new kind of home-study training in Radio, hundreds of men are today leading straight for financial independence! Radio pays from $2,000 to $25,000 a year. The work is thrilling . . . the hours are short. Vacations with pay... opportunities for seeing the world . . . adventure galore! Prepare at Home with this Big Laboratory Outfit Get the “How” as well as the “Why” of Radio—with this expert training! Only an hour or so a day—in spare time—is all you need! As part of your course, you receive absolutely free of extra charge—a magnificent outlay of apparatus. With this outfit you learn to build fine sets and solve the problems that bring big pay. Training sponsored by RCA .... General Electric .... Westinghouse Our graduates are in big demand everywhere. They enjoy greater success because they’re posted right up- to-the-minute in everything in Radio. Radio’s progress eachyear is measured by the accomplish- ment of the great engineers at workin the research labora- tories of RCA, General Elec- tric and West- inghouse. These three Radio organi- Limited space permits of only asmall picture of the great outlay of ap- paratus given with the course. only 9 months! ‘By means of this “Big-League” home-training sponsored by Radio Corporation of America, General Electric and Westinghouse. Send for FREE BOOK about Radio- Radio Inspector $2,000 to $4,500 a year zations set the standards for the industry, and stand back of every lesson in the course. Money Back if Not Satisfied The lessons prepare you for success in all phases of Radio—manufacturing, servicing, selling, ship and shore broadcasting, Television, Photoradiograms and Radio equipment. A signed agreement backed by RCA assures you of complete satisfaction upon com- pletion of the training—or your money will be promptly refunded. Read This Thrilling Free Book It gives you the real “dope” about Radio and describes in detail thefamoustrainingthat has enabled usto place thousands ofourstudentsin fine positions,usually from 3 to 10 days after graduation. It may mean the turning point in your life. It tells in 50 fascinating pages and photos all about Radio’s brilliant op- portunities for adventure and suc- cess. Mail the coupon now—the book is absolutely free! Radio Institute of America, Dept. P.S.-2,326 Broadway, New York. Radio Institute of America Dept. P.S.-2 326 Broadway, New York, N. Y. Gentlemen: Please send me your big FREE 50-page book which tells | about the brilliant opportunities in Radio and about your famous lab- oratory-method of guaranteed radio instruction at home. > CRED CREED CUED CEES CEE CUED GD ERED GD GEEER

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Reading Architects’ BLU E P RI N TS Learn at Home! HE building trades are booming. Em- ployers everywhere are looking for men who can read architects’ blueprints. Splen- did salaries and rapid advancement are offered men who have this special training. ‘There is an easy, delightful way to learn, The International Correspondence Schools will teach you right at home in an hour a day of the spare time that now goes to waste. You will like the course because it is so PRACTICAL. You work on actual blueprints —the same blueprints a contractor would use if asked for an estimate, or a foreman would receive from a contractor. In a surprisingly short time you can ac- quire a knowledge of blueprints that will be of great value to you in a salary way the rest of your life. Mail the Coupon for Free Booklet ~ INTERNATIONAL CORRESPONDENCE. SCHOOLS ha Universal University’ er i 7616-F Scranton, Penna. Without cost or obligation on my Please tell me 4 N can qualify for the ) peaktion or in the subject before I have marked wae READING ARCHITECTS? BLUEPRINTS Architect Electrical Enginee itractor and Builder Electric Lighting Architectural Draftsman . Mechanical Engineer wrete Builder a Mechanical Draftsman Structural Engineer Pract “m. _— yo iy 4 rplane Engine Operatin; |Au'omobile k Civil Engineer ” a. ury and Mapping Radio [() Navigat ring m Enginee BUSINESS TRAINING “DEPARTMENT [Business Management paiement dvertising Management Business Correspondence ‘ersonnel Management how Card and Management Sign Lettering Accounting and C.P.A, nography and Coaching English Cost Accounting Civil Service Bookk BE cats Railway Mail Clerk \Common School Subjects Spanish o High School Subjects Tilustrating Cartooning Name Address.......... ia eccsdbictectiehractoce Se Occupation Persons residing in Canada should send thie coupon to the Anternational Correspondence Schools Canadian, Limited, Montreal, Canada LEARN TO i he Go LIN WHERE ET the same complete, thorough, founda- eas training that Lindbergh received. it now—under great soreves facilities at the Lincoln Airplane School. Much better than when Lindbergh learned Se Get the best training now available. we com- petent experienced instructors teach you prac- tical Flying and Ground Work. You go right up into the sky in our famous Lincoln Page Govern- ment Licensed Planes—with transport pilots. Learn on actual | a and motors su sup lied by the — Aircraft Factory. Write for nformation »_ LINCOLN AIRPLANE SCHOOL 211 Aircraft Bidg., LINCOLN, NEBR. MONEY MAKING OPPORTUNITIES SECTION Building the Greatest Bridge (Continued from page 20) that they are topped by only four or five Man- hattan skyscrapers—workers balance them- selves on narrow steel girders, crawl perilously along thin ledges hundreds of feet above the water, and toss red-hot rivets like jugglers. — On the New York bank of the river, along stately Riverside Drive, a mammoth steam shove if droning and panting from behind a green fence, picks up 15,000 cubic yards of rock at one time. Aloft, a 325-ton traveler crane grinds ponderously around, hoisting enormous masses of material that form its own rising pedestal. An endless conveyor belt, crossing the New York Central railroad tracks, carries sacks of cement and gravel from river lighters to the tower. From across the water comes the constant boom of blasting as tunnels are bored and a man-made ¢anyon is cut through the Palisades. PROBABLY the most intricate problem which the engineers faced was offered by the massive Palisades on the New Jersey side and the lack of such rocky heights on the New York shore. The Jersey stone gives ample anchorage for the big cables—thirty-six inches in diameter—from which the bridge will be suspended. But on the opposite bank, anchor- ages required a mass of concrete almost an entire city block in area and as high as a four- teen-story building! Such immense anchors are needed, for each cable must be able to re- sist a pull ‘of some 65,500,000 pounds, caused by its own weight and that of the structure it will help to carry. The cables on the Jersey bank are being buried deep in two vast wedge-shaped tunnels, bored through the rocks. These enormous caverns are to be filled with concrete. To erect the concrete anchorage on the New York side, a modern concrete plant had to be established temporarily in the midst of one of New York’s exclusive residential sections. Here two huge mixers grind out 1,000 cubic yards of concrete each day! Another engineering job of the first magni- tude was the construction of the great piers on which the cable towers stand, especially on the Jersey side, where they are located in the se about fifty feet from the water’s edge. showed that bedrock pitched sharply — coe how the shore to a depth of seventy-nine feet. Not only was this rock uneven, but it was covered with a fifty-five-foot layer of mud. This problem was solved by sinking huge cof- ferdams—four-sided boxes open at the top and bottom and strong enough to resist terrific out- side water pressure as the water within was being pumped out. In this manner, the rock floor was exposed and then solid blocks of con- crete were built inside the caissons. These blocks form the bases for the two legs on which the New Jersey tower rests. And the legs need to be sturdy, for each of the cable towers con- tains 20,000 tons of steel—the weight of 10,000 automobiles! How much will such a huge suspension bridge sag, and how will wind and weather affect it? Here is the engineers’ answer: The bridge floor will have a camber or arch of eleven feet, giving a clearance, under normal temperature and without a load, of 206 feet above mean high water at the center of the bridge and 195 feet at each tower. This provides the required elasticity, so that the structure will be able to adjust itself to expansion and contraction in its cables during summer heat and winter cold. But under abnormal circumstances, for ex- ample, on a very hot day when the bridge is burdened with an unusually heavy load, there will be a flattening out of the camber at the center of the span. In this manner, the floor will drop about ten feet and still have an emergency safety margin. 1929 ATLAS} Given to readers of Popular Science M. who take advantage of this offer now madeny connection with Webster's New - International Dictionary “Wwee* The “‘Supreme Authority | A complete reference library in dicti form, with 3000 pages and type matter alent to a 15-volume encyclopedia, all single volume, can now be yours on the fol- lowing remarkably easy terms: The Entire work (with 1929 ATLAS) Delivered for $1.00 » and easy monthly nymete thereafter (on approved orders in United States and Can- ada). You will probably prefer the beautiful India-Paper Edition which is Reduced About One-Half in thickness and weight as com- pared with the Regular Paper Edition Over 408,600 bane wd Terms and in ad- dition, 12, 000 Biographical Names, nearly 32,000 Geographical Subjects, 3,000 pages, 6,000 illustrations. Constantly improved and kept up to date, “To have this work in the home is like send- ing the whole family to college.’ To have it in the office is to supply the answers to countless daily questions. To Those Who > . G.&C. MERRIAM CO. Dept. S., Springfield, Mass. Please send me free of all o bligati 5 let infor: i "125 yp Bm ti with f to — answers, striking PPecsintte Color Plate”’ of the new bindings, with terms of your Special Atlas Offer on Webster's New Internati ti y to readers of Popular Science. 2-29 pih bbs ph hpi iii bh pi hb bb bb beh, 4 rd da dada hrtadndadindindadindindlindlindl Tweet NEW INDUSTRY NEEDS MEN COMPRESSOR [f CONDENSER m YAPORATO TSS EXP, ELECTRIC REFRIGERATION Calls You Newest American industry needs men for $200 to $1,0008 month jobs in production, service, installation and Fastest growing money-making field— backed by General Motors, General Electric, ete. New easy home training ifies you for big pay job. This training is endorsed by Servel, Kelvinator Norge, ond other large manufacturers. ‘*Opportunities in Electric Refrigeration reveals amazing plan to ambitious men. Sent free. No obligation. Be the first in your neighborhood to get into this new magic in- dustry. Write today. Utilities Engineering 3120 N. Clark S8t., 1ON VALVE Institute, Dept. 22, Chicago, Til. February, i9y februa

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MONEY MAKING OPPORTUNITIES SECTION 148

Big ger Pay for You in ELECTRICITY HIS giant industry is constantly

S What a Practicing X

Engineer Says of calling for more trained men to Film-Way Training fill jobs that pay $70 to $200 and Charles E. Fie, M.E.E.E., more weekly. You can fit yourself for ate 1 ~ . . 7 . Steinmetz in the ¢ a big pay job in Electricity in a new We Help You Get the Job ror a pars eee and amazingly easy way. At home, in and More Money ly and simply you explain your spare time, with real moving ; The points are so much pictures to guide you, youlearnhow Our employment service starts working for easier to grasp than by the do el ical k d ou the moment you enroll for Film-Way usual methods of instruc- 60 60 COCO Ws Se weining. Baaployers want rn Wey oor make quicker, surcr pros: soon ready to enter big pay ranks. men and we Keep our students in touc ress. Your whole cours ° ° with — yb ore sa lacing them ry eneees . S ty ‘ . ~ ss . ‘ \ a ee s, ~ ‘% Ne 2a “ s, . . \ ., .. % *, . ., ‘, ba 4 SSO eR RIESE FOES EIR RN REE RRS NRE RE enema Aner

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146 | Here’s the Answer | to every question about the principles, methods, or appa- |} ratus of radio transmitting and receiving. a? ee 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 n either for amateur operation or to qualify for a government license as operator or inspector. Prepared by Official Ex 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: ee Motors and Generators; Storage Batteries and harging 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 N ew 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 t 6004-C; Navy Standard 2-kilowatt Spark Transmitter; etc.; etc. Every detail up to the minute. Free Examination “The Radio Manual’ has inet been published. Nearly 700 . 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. | 6 Warren St., New York me THE RADIO MANUAL for examina- | J Send tion. Within ten days after receipt I will either return the volume or send you $6.00, the price in full. (Pop. Sc. M. 2-29) MONEY MAKING OPPORTUNITIES SECTION Animals Really Think (Continued from page 25) ening snarls! ‘‘Never mind,” his master said then; “it’s all right now.” And instantly a gentle expression returned to Fellow’s big brown eyes. Fellow’s first psychological test was de- scribed in Poputar Science Monrtaty for January, 1928. Since then, he has learned many more words and also has developed a new achievement. He now responds to Her- bert’s injunctions when the master is hidden from view. Scientists who watched the latest experi- ments expressed the opinion that few children of four or even eight years could carry out so many commands with such promptness and proficiency. They concluded that in his mind the dog has stored an amazing number of definite associations between objects and word sounds; in other words, he had done what youngsters do when learning to talk. HE tests conducted with Black Bear and Fellow are outstanding instances of the activity in a new science, known as animal psychology, which has for its purpose not only to show that animals have intelligence, but also to det2rmine to what extent and how they use it. Some scientists think that if a white rat, a bright dog, and a six-year-old child were to be given the same intelligence test (an experiment which as yet has not been made), it is doubtful whether the child would come out the victor. And Dr. William T. Hornaday, who two years ago retired after twenty-eight years of service as director of the New York Zoological Park, says: “If every man devoted to his affairs and the affairs of his city and state the same measure of intelligence and honest industry that every warm-blooded wild animal devotes to its affairs, the people of this world would abound in good health, prosperity, and happiness!” Do animals think? Personally I believe that there is no longer any question about it! What but intelligence could account for the ingenious doings of Black Bear and Fellow, and for the all but human performances of the clever horses and dogs in the motion pictures? Thousands have seen and admired Rin-Tin- Tin, the famous German shepherd dog that is one of the highest-priced movie stars. While his acting on the screen is fine and vivid, it is “on location” that his true innate intelligence comes to light. OT long ago, Rin-Tin-Tin was making a picture in which he rescued a child that | had been abducted by the villain. The actor, in the character of a tramp, jumped a freight car, pursued by the dog: Aboard the train, Rin-Tin-Tin fiercely attacked the man and hurled him from the moving car. The actor was very much the worse for wear after this scene had been “‘shot.”” Then, to show that it was all in the day’s work and that there were no “personal”’ feelings involved, Rin-Tin-Tin rushed up to the battered villain, licked his hands, and in many other ways assured him of his unbroken friendship! Another time, the dog showed strikingly that his intelligence controls his instinct. He had received his final instructions for the act- ing of a thrilling scene and the director gave the command, “Camera!” when Rin-Tin-Tin saw a mouse scampering across the set. For a moment he stood undecided, struggling be- tween two desires. Then the actor triumphed over the hunter! Dutifully he went through with the sequence; but as soon as it was fin- ished, he bounded away and did not return until the mouse had been caught and killed. Flash, the police-dog movie star, valued at $100,000, recently was featured in a picture that showed him as | (Continued on page 147) Very Special COMPLETE Learn QUICK—Right at Home —To Make $50 to $200 a Week! For the first time YOU can have complete training in any branch of Commercial Art—from this 14-year old, nationally famous Art School— for only $4.98, or your Money Back. NOW you can learn right at home; get ready quick to make Big Money. We start you at very beginning, give you everything you need. Thousands Have Succeeded with these Same Complete, Easy Courses These same Courses have started thousands toward $50, $100 and more a week! mee list order AT ONCE to WASHINGTON SCHOOL OF ARTS {cli#hted 1115 - 15th St. N. W. ELECTRICAL EN ical | et n 26 in B. 8, ty. EARN WHILE YOU LEARN! Our quployment Department will belp you secure position to which you may a part of Le fee Wider fact WEOE a FREE CATALOG FREE, “iluscretog out iali: Granite and’ the ‘detaie of out aoe Wile, You Lean” Mention age, education, and the course you are interested Only 4 Motions used in playing this fascinating instrument. Our native Hawaiian Instructors teach you to master them quickly. Pictures show how. Everything explained clearly. Playin Half Hour Easy Lessons After you get the Even if you don't four easy motions little practice. No clear pictures make revious musical it easy to learn quick- nowledge needed, ly, Pay as you play. GIVEN _ 220225 72 —a sweet toned LF HAWAIIAN GUITAR Case WRITE AT ONCE for attrac: and Playing eee att GsvacTi® S| Value $18 to $20, OTHER } Tenor Banjo, Violin. Tiple, Tenor Guitar, Ukulele, COURSES | Banjo Ukulele. Under well - known instructors, FIRST HAWAIIAN CONSERVATORY of MUSIC, inc, 9th Floor, Woolworth Bidg., Dept246 New York, N.Y. 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peter, 1929 MONEY MAKING OPPORTUNITIES SECTION 147 ° e TT disks Really Think Wi (Continued from page 146) rain ou nine counterpart of Houdini. In the course of the story, Flash was locked in a sack ; a. ome to and bound with ropes. When the director pro- ; “2 Bes | were angry growls from Flash. In a — or two, the dog freed himself with his to show him how to loosen his bonds F S lI ose Your and sundry wrigglings of the body, while © Puce vgn man calmly “shot” the exciting » © y one of | || ene, Another motion picture animal that fj ) NEY tedly has given indications of intelligence ’ mimerchl oer, the wonder horse. e EX'S and Black Bear’s uncanny powers recall the marvelous accomplishments of Clever Hans, the horse trained by Wilhelm yon Osten in Germany, which, from 1906 to 1910, aroused the scientific world. Hans pos- sessed all of Black Bear’s ability, but, in addi- tion, could recognize people from a previous ‘| glance at their photographs! The animal caused much controversy among the German professors. Numerous tests were conducted, ‘| and it was finally concluded that Hans was If you are earning a penny less than $50 a week, send for m book of information on the opportunities in Radio. It’s FREE. Clip the coupon NOW. A flood of gold is pouring into Radio, creating hundreds of big pay jobs. Why go along at $2", $30 or $45 a week when the good jobs in Radio pay $50, $75 and up to $250 a week? “Rich Rewards in Radio” gives full informa- tion on these big jobs and explains how you can quickly learn Radio through my easy, practical home-study training. \g “fake” and his performances a “mind- $375 One ” stunt. All this happened before Month In Salaries of $50 to $250 a Week Not Unusual —not to mention animal pey- Spare Time The amazing growth of Radio has astounded the world. Ina was taken as seriously as it is today. y it never occurred to the professors that a “mind-reading stunt” presupposes the “Recently I] few short years three hundred thousand jobs have been created. made $375 in] And the biggest growth is still to come. That’s why salaries of one month in aye: ’ $50 to $250 a week are not unusual. Radio simply hasn’t got . : : s my spare time installing, , 1 a of a mind with which to read other servicing, selling Radio nearly the number of thoroughly trained men it needs. : ets. They were, however, probably right in one - You Can Learn Quickly and Easily in Spare Time u TB pd , age hac! —— = ager ig Hundreds of N. R. I. trained men are today making big | plishments of animals traine mee, OF ee Haverhill, Mass. money—holding down big jobs—in the Radio field. You, too, such constant contact with him t imitation . d . Radi v h 1 : Side ener satin, Oo att dine the should get into Radio. You can stay home, hold your job, becomes a fairly cca ait nates tana $450 a learn in your spare time. Lack of high school education or cena whether ates tatake a ale Month Radio experience are no drawbacks. own accord, — must either a od —. in Big gh hu. Many Earn $15, $20, $30 Weekly On the Side wat the top of the intellectual ledder® so far aad toe eee ee e top of the intellectua r, so far est an t- ee en ki ey il ; . p Radi you to begin making money shortly after you enroll, as Pegged —_ q a stand, ~ shop in the Southwest andj My new practical method makes this possible. I give you SIX course, A an “poe " spines ° tole " also —. KGFI. we BIG OUTFITS of Radio parts and teach you to build practically _ the + oe pa od at = other: a ee every type of receiving set known. M. E. Sullivan, 412 73rd ae hir on tn list aa ta Inlien Frank M. Jones St., Brooklyn, N. Y., writes, “I made $720 while studying.” , Reet. In the specialised department of 922 Guadalupe St. . W. Page, 1807 21st Ave., S., Nashville, Tenn. “I picked up . : San Angelo, Tex. 935 in my spare time. domestic economy, the beaver—the architect and engineer of the animal kingdom—mani- I e 6 * : Your Money Back If Not Satisfied fests more intelligence, mechanical skill, and Ive y , My. course fits you for all linee—menufacturing, selling, 7 ° . TVIC. sets, ’ reasoning power than any other wild animal. dio Ss. Tie enti a bevedeasing Geek amatint on beers ¢ back up my training with a signed agreement to refund est cunning and foresight to the common build100 Act NOW—64-Page Book Is Free brown rat! AS for the apes, almost every one — circults. Send for this big book of Radio information. It has put . i hundreds of fellows on the road to bigger pay an ccess. well-trained chimpanzees do their amus- | Q@F@ 3. Get it. See what Radio offers yeaa ow ioe. ing imitative stunts on the stage and in the ment Department helps you E ; - get inte Radio after you movies. But it was left for the officials of the graduate. Clip or tear out New York Zoological Park to discover that the the coupon and mail it ——— orang-utan possesses native inventive genius! RIGHT NOW. SS Some years ago Dohong, an orang-utan, de- J. E. Smith, President veloped a faculty for mechanics and invented oe re the lever as a mechanical force as fairly, perely, and independently as Archimedes vered the principle of the screw! |} It was a great day for Dohong when he } found he could break the wooden one-and-a- )} half-inch horizontal bars that were held out 1 from his cage walls on cast-iron brackets. Be- fore his keepers could stop him, he had glee- fully destroyed two and was attacking the third —with a broken piece used as a lever! Promptly the bars were replaced by larger ones, of harder wood, but screwed to the same cast-iron brackets. For a while, Dohong was stumped. But soon the wise old ape con- ceived the notion of swinging his two-inch oak trapeze bar far over to one side of his cage and And in the matter of self-preservation, zoolo- ists reluctantly hand the palm for the great- W every penny of your money if, after completion, yl . P a ith them can sot satisfied with the a pe lesteustlons I ive yous Radio set Here NATIONAL RADIO INSTITUTE Washington, D. C. J.E. SMITH, President Dept. 9NQ, National Radio Institute Washington, D.C. Dear Mr. Smith: Send me your Free book “Rich Rewards in Radio,’’ giving information on the big-money opportunities in Radio and Nerd ractical method of teaching with six Radio Out- ts. I understand this places me under no _| of applying the bar as a lever, inside the hori- obligation. ;{ zontal bar, from above. Naturally, the 9 Be brackets gave way. They were replaced with WB asace.s 0000s a cede a ea heavy brackets of flat wrought-iron bars, one MRS. :.. .. .500ssseetewindssenn tyaneeel half by two and a half inches, fastened with City sggige Hay heavy screws. (Continued on page 148)

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An Y MAN who can read and write and use a pair of pliers can become an electrical expert and free himself forever —_ the long hours and drudgery of a sma re 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 = im £-3-l'inn'd zi AGENTS $6 A DAY taking orders for No-Frost—the amazing new preparation that keeps rain, snow, frost, mist and steam auto windshields, show windows, mit A sensation ev rors, etc. No hunting owners, bus ‘$83 ays. furnish chance. where. ing

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cf i iit ie az a fi ii < f if ii a i ili! i ge ! 3 z Bsg6e oS # ; ee

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pebrvary, 1929

| Be Rewiring Simplified -.¢ a wire from each binding post on the set that is marked for a C-voltage over to gither the minus-A or plus-A binding posts. The remaining wiring is to apply the volume potentiometer marked V in Fig. 2 can do it as shown in Fig. 2, or the same result can be accomplished by connecting the outside terminals of the potentiometer to the and ground binding posts of the set connecting the center terminal of the potentiometer to the antenna lead wire. (Continued from page 66)

fp YOUR set is an old one not fitted with ‘the power tube 171, there will be no output tansformer such as is shown connected be- the P terminal of the socket marked y7i-A and the 180-volt binding post. You can ft one by following the connections shown in @, or if there is no space inside the cab- jnet, the output transformer can be externally by hooking the loudspeaker to the terminals of the transformer and con- necting the input terminals to the plug that ‘wes in the loudspeaker jack on the panel of set, or to the loudspeaker binding posts, if po jack is provided. All of the new wiring above detailed and illustrated in Fig. 2 is shown in heavy black All that remains is to connect the B- diminator to the receiver. It has been left out of the diagram of Fig. 2 so as not to con- fuse you on the rewiring. Connecting the B- eliminator is very simple. The binding post marked minus-B on the eliminator is con- nected to the similarly marked post on the receiver. Then you connect the binding post on the eliminator marked ““DET” to the 45- volt binding post of the diagram in Fig. 2 and to the center tap binding post of the 214-volt winding on the filament heating transformer. In your receiver this binding post may also be marked “DET.’’ Connect the 90-volt binding post on the receiver to the binding post on the eiminator marked “90,” “AUDIO,” or “INTER.” Then connect the binding post on the eliminator marked “180” or “POWER” to the 180-volt binding post on the receiver. You will find that the filament-heating trans- former has a socket into which the plug con- nected to the B-eliminator can be inserted. ‘Leave disconnected the remaining binding ‘posts on the receiver. THE receiver can be turned on and off by * inserting and pulling out the plug connected to the filament heating transformer or, if you prefer, a cord switch can be connected into the cord from the filament-heating transformer. The volume is controlled by turning the knob of V. If you encounter difficulty with whistling or squealing, insert 1,000-ohm fixed Iesistances at one or both points marked X in Fig. 2. If there are any points that do not seem | quite clear to you or if you wish additional information, address your letters: | Technical Editor, Poputar Scrence Monraty, 250 Fourth Avenue, New York City. Measuring Road Roughness OW rough is a road? A new recording de- vice, known as a “‘roughometer,”’ which can be attached to any automobile, answers the question. It measures in inches the amount the mines are compressed as the machine bumps ng a stretch of highway. A comparison of the records of two runs at the same speed over [equal distances on two: different highways shows accurately their relative roughness. The device was developed by the U.S. Office of Public Roads to test highway surfaces. A Bumber of state highway departments have adopted the new invention.

pHi !

MONEY MAKING OPPORTUNITIES SECTION 149

————- ~

Low. PAY LONG HOuRS No FUTURE

I Said Good-bye to It All After Reading This Amazing Book-

Ww a man who has been struggling along at a low-pay job suddenly steps out and commences to earn real money— $5,000, $7,500 or $10,000 a year—he usually gives his friends quite a shock. It’s hard for them to believe he is the same man they used to know. . . but such things happen much more frequently Raised My Earnings 7007! PRE A Few Weeks—Then Bigger Pay There was nothing “different” about od 4 wen Be penn Bp started. one of them any speci: vantages— SALES- although all of them realized that MANSHIP offers bigger re-

than most people realize. Not wards a any gas ya only one, but }HUNDREDS Income sion under the sun. But, like have altered the whole course Your many other men, they ” sub- of their lives after reading the Multiplied or scribed to the foolish belief amazing book illustrated | YouPayNothing | that successful salesmen are above. N. 8.7. A. e now offering,to | born with some sort of “magic True, it is only a book— | HrusBen"Bare Dems | sift.” “The Secrets of Mod: : rine Be is on yo od yous definite stipulated Sesnres | =sern amic Salesmanship printer’s ink—but it contains | Saad RSaseeee | Ody bet fencer treme he * : ee ou no y is daring offer is - rescues thn any amiktions | eeceerenet tas: | zu Solosmanship is just yy Se other profession. | can yf S ae a Sharir eerie has certain fundamental rules and secrets tha Open al- | ost snd lereecinimnedates | @nd laws—laws that you can most any man’s eyes to things | for fuil details. master as easily as you learned

he has never even dreamed of! Remarkable Salary Increases For example, R. B. Hansen of Akron, Ohio, is just one case. Not long ago he was a foreman in the rubber-curing room of a big factory at a salary of $160 a month. One day this remarkable volume, “The Secrets of Modern Dynamic Salesman- ship,” fell into his hands. And from that day on, Mr. Hansen clearly saw the way to say “good-bye” forever to low pay, long hours, and tiresome routine! Today he has reaped the rewards that this little volume placed within his reach. His salary runs well into the 5-figure class—actually ex- ceeding $10,000 a year! Another man, Wm. Shore of Neenach, California, was a cow-boy when he sent for “The Secrets of Modern Dynamic Sales- manship.” Now he is a star salesman mak- ing as high as $525 in a single week. O. D. ‘Oliver of Norman, Oklahoma, read it and jumped from $200 a month to over $10,000 a year! C. V. Champion of Danville, Illinois, raised his salary to over $10,000 a year and became President of his company in the bargain! the alphabet. City and traveling sales positions are =“ in every line all over the country. For years, thousands of leading firms have called on the N. 8S. T. A. to supply them with salesmen. an service is free to both employers and members, and thousands have secured positions this way. Free to Every Man See for yourself WHY “The Secrets of Modern Dynamic Salesmanship” has been the deciding factor in the careers of so many men who are now maki $10,000 a year. Learn for yourself the REA TRUTH about the art of selling! You do not risk one penny or incur the slightest obligation. And since it may mean the turning point of your whole career, it cortaialy is worth your time to fill out clip the blank below. Send it now! National Salesmen’s Training Association Dept. 191-B N.S. T.A. Bldg., Chicago, Ill. [ National Salesmen’s Training Assn. Dept. 191-B, N.S. T. A. Bldg., Chicago, Il. 4 1 Without cost or obligation, send me your free book ‘“The Secrets of Modern Dynamic Salesmanship.’’ Also include a free Sony of t me a definite the new N.S. T. A. money. assures ' addition to my income with months after completing | training—or a complete re: of tuition fee. ] J NAMe..........cecccccccccesesescccercessscess | J Address. ...........ceceeeee see ecer cence vevees | § Clty... cc. cece ccc eeesseneses ee eee |

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tep Into Aviation ' ' Adventure Thrills Big Money!

RE you a red-blooded, daring he-man? Do you crave adventure, ey, admiration, and the 7 of great crowds? Then why not get into the Aviation In- dustry—the greatest ad- venture since time began —the greatest thrill ever offered to man?

Think what Aviation offers you. The praise and plaudits of the multitude. And a chance to get in on the ground floor where rewards may be unlimited! Aviation is growing so swiftly that one can hardly keep track of all the astonishing new developments. Air-mail routes have just been extended to form a vast aerial network over the entire U.S. Many Com- a = edeuareaes ss

0: ce es ee

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z: H Sip ble g ° i i pet} ai i ill F Pd a ~~ & =f i FS rH: MONEY MAKING OPPORTUNITIES SECTION Tides Make the Earth Boil Over (Continued from page 45) practically every active volcano in the world is located not far from large bodies of water, the theory is advanced by Dr. William Bowie, of the U.S. Coast and Geodetic Survey, and others, that the kneading action of the sodic tides twists the earth, forcing up the = and causing volcanic activity. Concerning the source of the heat that forms molten rock, or magma, one theory is that increasing internal pressure causes it. A second js that the heat is produced by chemical action. Another is that the friction of shifting layers of rock generates it. Major C. E. Dutton, a geologist of the U. S. Geological Survey, has advanced the idea that the real secret is radium! Radioactivity in the rocks, he says, is sufficient to melt them in certain , forming large subterranean pools of = Added weight is given to his suggestion by the report of Dr. John Joly, British geolo- gist, that radium is present in all igneous rocks. NCE lava leaves the crater of a volcano, its course down a mountainside seems gov- erned by caprice. In the recent Mt. Etna eruption, a beautiful grove of lemon trees lay in the path of the crimson avalanche. But, just before it reached the trees, the fiery stream seemed to pause. It turned aside and attacked a heavy stone wall, which it crushed as though it were pasteboard. At another place a gambler, taking a long chance on his luck, offered a trifling sum for a villa that seemed doomed by the approaching lava. No sooner was the bargain struck than the stream divided into two parts, cutting off acorner of the garden but avoiding the house! Why do people persist in erecting homes on the oe of these menacing mountains? Dr. H. S. Washington, noted volcanologist of the Carnegie Institution, explains that nowhere in the world is there such fertile vineyard und as that produced by weathered lava. The famous grape areas of northern France and southern Germany, as well as those around Mt. Etna in Sicily, are rich in this material. To safeguard homes near volcanos, many attempts have been made to govern the flow of lava. A sugar mill owner in Hawaii is reported to have saved his buildings by pouring water on the advancing front of a lava stream. The water “froze’’ and hardened the lava until }a dike had been formed to turn the main stream aside down a gully. A few years ago, scientists shot chemicals into the crater of a voleano in South America in experiments to control its activity, but without success. [UNTOLD fortunes in gases and chemicals valuable to industry are wasted in the atmosphere every time a volcano lets go. “The Valley of Ten Thousand Smokes,” in Alaska, a volcanic field formed by the eruption of Mount Katmai in 1912, has been called a gigantic chemical laboratory. Here thousands of fuming holes in the earth vomit steam and gases, the volume of which has been estimated at 6,000,000 gallons a second! The chemicals thus thrown away each second, according to Dr. E. G. Zies, of the Geophysical Laboratory, include sixty-four pounds of hydrochloric acid, twenty-two pounds of hydrogen sulphide, which has many important uses in industry, and nine and a half pounds of hydrofluoric acid, used for etching glass. It has been esti- mated that these chemicals, if they could be captured and put, to_yse, would be worth $17,000,000 a year—more than twice the price paid by the United States for Alaska. Many mysteries beneath the earth’s crust remain to be penetrated, however, before men can hope to harness the destructive mountains. Science today is surer of what goes on millions of miles out in starry space than it is of what "| takes place beneath our feet. DRAWING OFFERS | PLEASURE WITH PROFIT HAT would you give to be this artist—earning a big income—enjoying studio life? He has learned the secret of forming simple lines into finished illustrations. It was only a short time ago that this young artist filled out a coypon like the one below and mailed it to the Federal School of Illustrating. Now he is not only trained in modern art on which magazines are spending millions every year, but he has also had thorough instruction in all branches of illustration. Careful training by Federal Instructors has taught him to turn simple lines into dollars. 3 More than fifty famous artists—making big incomes them- selves—have contributed to the Federal Course. Clare Briggs, Neysa McMein, Sid Smith, Fontaine Fox, Charles Livingston Bull, Norman Rockwell and many others teach you their “tricks of the trade” about illustrating, cartooning, lettering, poster de- signing, window card illustrating, etc. Why drudge at routine work? Opportunities for artists have never been better. Drawing is easy to learn the Federal - Home Study way. Earn while you learn, if you wish. Many students find a market for their work after a comparatively short time of study. Test Your Drawing Talent If you like to draw, train your talent. Open the way to success and a fine income. Write your name, age and address on the coupon and get our Free Book, “A Road to Bigger Things,” illustrated below. With it, you will receive our Free Vocational Art Test to find out your ability. Hundreds of successful artists got their start by sending for these. This is your opportunity—grasp it. Mail The Coupon Now FEDERAL SCHOOL of ILLUSTRATING 2149 Federal Schools Bldg. Minneapolis, Minnesota send me free book “A ROAD TO BIGGER THINGS” and Standard Ast Test.

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~ ‘ 152 MONEY MAKING OPPORTUNITIES SECTION fe to School at Hy ‘ A a PsA Vt tlt Md tf HIGH 1 SCHOOL COURSE IN TWO YEARS YOU ARE BADLY if you tack HANDICAPPED [224 Scho! SS eens ie hestosen ox socist prominence. You are barred from the leading professions, from well- paid civil service jobs, from teaching and college entrance. In fact, em- ployers of ically all worth-while itions demand High School train- . You can’t hope to succeed in the face of this p. But you can remove it. Let the American School help you. FIT YOURSELF FOR A BIG FUTURE This course, which has been prepared by some of America’s leading professors, will broaden your mind, and make you keen, alert and capable. It is com- plete, simplified and up-to-date. It covers all subjects given in a resident school and meets all requirements of a High School training. From the first lesson to the last you are care- = fully examined and coached, USE SPARE TIMEONLY Most people idle away fifty hours a week, Probably you do. Use only one-fifth of your wasted hours for study and you can remove your present handicap within two years. You will enjoy the lessons and the knowledge you will gain will well repay the time spent in study. Check and mail the coupon NOW for full particulars and Free Bulletin. American $chool Best. H-275, Drexel Ave. and $8th S$t., Chicado et eo American School Dept. H-275, Drexel Ave. & 58th St., Chicago $ ¢ i The Real Fathers of Flight (Continued from page 44) craftsmanship that enabled them to build the airplane. Their first experiment in wind pres- sure was made with a whirligig on a bicycle which they pedaled through the streets of Dayton. Their historic first flight of 1903 at Kitty Hawk, N. C., would have been a fiasco without the saving virtue of a small portion of bicycle cement! Wilbur was twenty-five and Orville twenty- one when the brothers opened their bicycle repair shop. “If you want your bicycle fixed right, take it to the Wright brothers,” was the word shortly passed around Dayton. “They are reliable, and fair in their charges.” ‘THE business grew into the sale of new wheels and trading in old ones. In four years the p ring owners had their own model to offer the public, the Van Cleve bicycle, named after an ancestor who helped to found Dayton. The machine was assembled by the brothers from purchased parts, yet it was first class and up-to-date. About a dozen of these wheels were sold the first year at a price around $100. The assembling shop on William Street had good equipment that included an enamel- ing oven. Orville had typhoid fever in 1896. He was looked after jointly by Wilbur, a trained nurse, and Katharine, home on summer vacation from Oberlin College. I can see Wilbur waving a palm leaf over the fevered patient, keeping it up with monotonous regularity, changing hands to rest muscles, perhaps speculating on a device for an automatic power fan. “Listen, Orv,”’ we can imagine Wilbur say- ing one day to his just convalescent brother, “‘you want to catch up on the news while you’ve been sick. Here 1s an item from Germany. Lilien_hal is dead.” “Li..-nthal?” “Yes, you know—the man who tried to fly with wings. Seems to me we both read about him in some paper or magazine along with the experiments of Maxim and Langley.” “How did 1t happen?” **Well, he made some short hops or glides as they call it. But the last time he fell somehow and got killed.” *‘Let’s read up on the subject, Orv,” Wilbur doubtless suggested. “I'll get what there is in the public library and you know father has a book on bird flight downstairs—Animal Mech- anism, by a Frenchman, Professor Marey. We’ uy find. out what there is in the whole busi- ness.’ HAL. an invalid through the autumn, Orville heard his brother read aloud the thin and tenuous documents dealing with flight. Flying then was on a par with spiritism. It had no scientific basis or repute. The literature was meager though inflated with words and cloudy guesses. The brothers, hungry for definite information, tried to find something to put their teeth into. They now took turns in reading aloud on winter evenings at home. After reading, they talked, argued, dreamed, and added cloudy guesses of their own to the. fog-enveloped, illusory, and haunting topic. The brothers were just playing with a fascinat- ing idea, amusing themselves. But the idea grew upon them. Perhaps at moments each had a secret vision of adding a tiny footnote to history. The footnote would be in small | , type. It was several years before they saw how that type might enlarge and come to be the main text of the book of avjation. The bicycle men of Dayton were now in the vigor of early manhood. While not robust, they were wiry and athletic. They codperated remarkably in (Continued on page 153) February, 199 WAT Sey Wipe Mb may have it my, A Whole THE OPEN ROAD For bors MAGAZINE. Y Fis 7 gesese month crammed with €a 5° © lives red.b! Breathless *:.: Wer a ea aS Jus st dro citer Jone drop gdola fet 130 Newbury St., Soscon, Mass, Friends: Here’s my $1. "Rush me the electric motor Heretor one year for THE OPEN ROAD FOR ty MAGAZINE. bo¥s | Name. « «= = 222 2220 o-oo oo enn ee enn ene e ewww eens Be an electrical specialist. Gain quick success in this most fascinating and profitable field. Learn at National in the centerof tremendous electrical projects costing more than $100,000,000.00 —unlimited opportunities now. Practical, intensive training by National's j ience method in 6to9 ane. All technical essentials included. School endorsed by leaders in'electrical industry. You learn all branches by of electricity; radio. Million dollar } institution; all modern uipment and training facilities, Life okekockip No age limit. Free employ. Jie FREES ment service. Over 17,000 successful ae 23rd Se ar, ie, ilusrared ROOK rite today. Dent TIONAL, 4006 So. Figueroa, ied Make Big Money! Build Bird Houses Boys! Here’s a real money making opportunity. With my simple instructions any boy can build and erect Grandpa Bird Houses. They sell at $2 to $30 each. It’s lots of fun and an easy and quick way to make spend- ing money. $2, worth sold in Oak Park, Ill., in one year. Send me only $1 for 16 Blue Print Drawings showing correct building plans for making my famous bird houses for Martins, Wrens, Flickers, Blue Birds, etc. You also get free valuable book about song birds and tips and advice on making sales. Get busy. Send $1 for my Bird House Plans so you can make money this spring. GaonGe J. BREIDERT 1043 N. Elmwood Ave. Osk Park, Ill. » Deere -B, 69 faa fone atone pcos Aacietee a7 Library, Low cot, cany ferme. Get oJ Yor them HOW, Extension University, Dept. Chicage The World’ S Largest Business Training institution \ § 7 FESSaaS @ = PESEREERERS BEST TSES SEH FeSe Bees aes re F ‘3 FFE 8s Te gas. SFE BEE

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MONEY MAKING OPPORTUNITIES SECTION a —— The Real Fathers of Flight (Continued from page 152) -«al as well as mental feats. For example, was starter for Orville when the latter in amateur bicycle races under aus- of the local Y.M.C.A. At the pistol Wilbur shoved and Orville sped five ahead of all rivals. The latter still ‘ches his medals of victory in these races. [saw them in his Dayton home. ; ; They found excitement in applying their wits to the solution of mysteries like that of the : pedal, which had baffled the scientific of manufacturers. The pedals were unscrewing, riders complained, although they were designed to tighten in use. The keenly ant Wrights detected the source of trouble and told a thankful manufacturer that friction of the pedal shank against the crank shaft negatived theory and unscrewed the pedal. HEY sharpened their wits also on mental hal so-called mind reading, and the tricks of spiritist mediums. They were keen scientific skeptics, putting a razor edge on their minds while training their bodies for a hazard- ous journey in the air. By force of circumstance they were compelled to build the flying ma- chine of their dreams entirely in their minds. Whereas noted experimenters of the day could rely on costly test models and laboratory in- struments, the two bicycle men had to think out every step and create a host of imaginary models which in turn they inspected, analyzed, criticized, tore down, rebuilt, and finally threw away. They went back to the ancient method and relied first on their brains. staged home battles on imaginary air- craft. It was the agreed duty of each brother to attack, punch, and smash with all vigor the other’s concept. Orville proposed, Wilbur knocked; Wilbur suggested, Orville swung a destructive blow. They often fought each other to a mental standstill but did not lose their tempers, for their object was a mutual quest of truth. After a fair fight the vanquished was quick to concede victory and to adopt his opponent's viewpoint. “T like to scrap with Orv,” Wilbur used to say, “because I like to scrap with a good each Taenctimes these idea-boxers chased each other around the ring so fast that at the gong each had reversed his position and stood in the other’s corner, which gave them a hearty HEY obtained some new points to fight over in May, 1899, from pamphlets of the Smithsonian Institution, The Aeronautical An- nuals of 1895-7, Experiments in Aerodynamics, by Professor Langley, published in 1891; atticles by Lilienthal, and parts of Mouillard’s Empire of the Air. They had already read Chanute’s Progress in Flying Machines. It was all a mess of conjectures, dreams, pseudo- science, and enthusiasm. But the last item— enthusiasm!—was truly valuable to the Wrights. It kept them going when facts and Treason seemed to have nothing to offer. The Maxim and Langley group of experi- menters believed in power flight, while the school of Lilienthal, Mouillard, and Chanute } practiced on gliding without a motor. The men of Dayton chose the gliding approach to the problem as more sensible and economical ile, too, they were fascinated by the notion of flying like birds. “Balance is the main problem,” we can im- agine the brothers agree after long debate. “And it isn’t practical to ‘seep balance in the Lilienthal and Chanute style with the rider shifting his weight six ways for Sunday. Half & minute in the air seems the limit for that acrobatic stunt. (Continued on page 154) 153 “Every 3,000 MilesThis Amazing Little Device Buys Me a New Tire...FREE” ‘*F TXHE money I save on gaso- line more than keeps me in new tires. Figure it out. ... I was using gas at a rate that cost me $46 to drive 3,000 miles. Now I’m getting better than 26 miles per gallon. It saves $23 to $25 every 3,000 miles—more than the price of a new tire.” No matter what make of car you drive, the Stransky Vaporizer is unconditionally guaranteed to give you more miles per gallon or it costs you nothing. As a matter of fact, it is not uncommon for the Stransky Vaporizer to greatly increase gasoline mileage! 43.8 Miles Per Gallon Mr. M. E. Miller, Kansas City, writes: ‘*You_peo- ple claim a saving of 25% or more of Gasoline. I have subjected the Va- porizer to a severe and thorough test. After in- stalling one on a Chevro- let, I found I was obtain- ing 43.8 miles to a gallon. The actual test surpasses your claim.”’ Less Gasoline More Power The vaporizer mixes air with your gasoline after it leaves the carbu- retor. Vaporizes the gasoline more thoroughly. Under this ideal condi- tion you get more compression out of less gasoline and a more complete explosion. Starting is not inter- fered with as the Vaporizer auto- matically shuts itself off when the motor is idle. Make This Test Test the Stransky Vaporizer on your car—and expect results that will amaze you! Increase your mile- age—forget carbon troubles, slug- gish motor and fouled spark plugs from over-rich mixture—and save enough on your gasoline to more than keep you in tires. These re- sults are guaranteed or the test Note These Records Forty-three miles per gallon from a Chev- rolet, reported by F. S. Carroll. He also reports forty miles on one gallon in a Ford. Forty miles per gallon in a Dodge from Brownsville, Tex., to Tampico, Mex., reported by T. L. Brown. Three Million Owners Records like these are reported’*in every mail for every make and model-car .:. . from 72 different countries . .°. the world over. More than three million Stransky Vaporizers have been installed. Easily Installed No bigger than a dollar coin—no more expensive than a good wrench—no more trouble to attach than a fan belt! Attaches to the intake manifold of any car in five minutes. Anyone can do it. $4 an Hour for Salesmen, Agents, and Spare Time Workers Men are making wonderful earnings showing the Stransky Vaporizer to car owners in spare time and full time. Sells fast under our guarantee. Foster made $357 in two weeks. G. F. Fuller earned $114 in 5 days. Eberlein sold 23 Vaporizers in 35 min- utes. J. W. Cronk actually earned $51 in an hour. You should be able to earn at least $3 every hour you put in. We offer demonstrators one Vaporizer FREE, under our unusual offer. Get full details. Simply mail coupon at once. costs you nothing. Mail the coupon below for full details, guarantee, and amazing trial offer, which is even more re- markable than we can tell you here. There is no obligation whatever. FITS ANY CAR IN 5 MINUTES Any one can install this device in 5 min- utes. Simply loosen one connection to the intake manifold with a wrench. You can do the rest with your fingers. J. A. STRANSKY MFG. CO. B-730 Stransky Block, Pukwana, South Dakota J. A. Stransky Mf¢. Co., B-730 Stransky Block Pukwana, So. Dakota Without obligation send me full details of your free trial offer. Check here for Distributor’s Sample Offer and the Selling Plan. pecececoccsccccascecesa,

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] i | { Mechanical Engineering Learn at Home Mecwanicat Engineering embraces the design, con- struction and operation of machines and machine It is a profession which offers almost unlimited opportunities to men whu combine natural mechan- ical ability with technical training. For this is The Age of Machinery convenience, luxury or necessity which we enjoy de- pends on machinery for its production or adaptability to our needs. Every new invention multiplies the opportunities for competent designers, builders, erect- ing engincess, etc. : e of the best ways to train yourself to secure @ position as a Mechanical Engineer is through the home-study courses of the International Correspon- ce Schools. These courses are complete and up-to-date, and they are especially arranged to meet the needs of the student who studies es Dome. a ti . They are particularly helpful ause they are written by well-known mechanical engineers who have had years of practical experience in this field oad oe know the quickest, best way to solve every problem. Just mark and mail the coupon and we'll gladly send you Free Booklets describing the I. C. S. courses in Mechanical Engineering or any other course in which you are interested. Mail the Coupon for Free Booklet SE —— re ee ee ee ee _ oo - INTERNATIONAL CORRESPONDENCE SCHOOLS “The Universal University” Box 7615-F, Scranton, Penna. Without cost or obligation, please send me a copy of your booklet, ““‘Who Wins and Why,” and full particulars about the subject before which I have marked an X: Almost every Mechanical Engineering Toolmakin Mechanical Course Blacksmithing and Forging D Patternmaking ng Mechanical Drawing Complete Shop Practice Electrical Engineering Electric Lighting C) Railroad Positions vo Spemees - urveying an appin Mining os Foundrywork Machine Shop Practice Architects’ Blueprints Contractor and Builder Architectural Draftsman Concrete Builder Structural Engineer Chemistry Pharmacy Airplane Engines Agriculture and Poultry Mathematics BUSINESS TRAINING COURSES a Steam Engineering | Architect Business Management Advertising Industrial Management Business Correspondence Personnel Management Show Card and Traffic a pe Sign Lettering Accounting Stenography and Cc. P. A. Coaching English Civil Service Railway Mail Clerk H Accounting French Common School Subjects High School Subjects Illustrating 0) C ing ) ee SEITE a COL ot Ly RRL De SOO City. State. MONEY MAKING OPPORTUNITIES SECTION $1900 to $2700 a year Long vacations with pay. Work easy. Travel on fast trains with all expenses paid, including hotel. No worries about the future. MY FREE BOOK TELLS HOW wn Pussi*ditet? Pon dice Clerk. City Mail Carrier. R. F, D. Mail Carrigr, Postmaster. can get o Government Civil Dervice Position. Till show you how: Rochester, The Real Fathers of Flight (Continued from page 153) Let me emphasize here that thirty seconds was the gliding record up to the Wrights and no man had flown a split second in a power machine. The record was indeed discouraging: Lilienthal the German and Pilcher the English- man killed in gliding, then the dismal failure of power apparatus built by Maxim, Phillips, and Ader. “Perhaps the birds can teach us,”’ said the brothers, echoing a thought that has run down the ages from cave man to da Vinci and our | own time. So on Sunday mornings the Wrights bicycled to a sandy point on the Miami River a few miles from Dayton, lay on their backs for hours, and studied the soaring flights of buzzards and hawks. At home they observed swallows and other small birds. “WE GOT plenty of flying fever from watch- ing the birds,’’ Orville told me a decade and a half later, “but we learned nothing about their secret of balance.” In fact, while the airplane wing warp or equivalent flap or aileron is a bird principle, the inventors did not then know it and made an independent discovery without debt to bird or man. In early June, 1899, the crude germ of the airplane was born in Orville’s mind. It was a notion of hinged wings to be moved alternately up and down in order to secure lateral balance. At first glance this was nothing original: since time began would-be flying machines had copied bird shapes from tail to beak. Wings had been hinged to obtain propulsion or just because the birds were built that way. The dis- tinct and original object in Orville’s plan was to get sidewise balance. However, the brothers agreed the idea was mechanically impractical. They seemed to discard it, yet it remained in the bottom of their minds as a thought. both rich and fertile. Some weeks afterward, in late July, toward ten o’clock at night, Wilbur was alone in the bicycle store, which was kept open evenings to serve mechanics and factory employees who had no leisure time during the daytime to shop. A customer came into the store and the talk was like this: “Say, Wilbur, I want an inner tube for my wheel.” “All right. Here is one.” “Good rubber, eh? Puncture-proof, too?”’ “No. They all puncture. Show you an- other if you like.” “Wait till I look this over.” “Go ahead.” He was that kind of a salesman. DLY twisting in his hands the pasteboard box in which the inner tube had been packed, Wilbur talked with the customer. His lean, work-scarred fingers gripped the corners of the box and twisted it in opposite directions. Wilbur glanced down, saw what his unconscious fingers were doing. His mind leaped from box to airplane wings! Here was the way to em- body Orville’s concept of sidewise balance through hinged wings. You can’t hinge but you can twist! The effect is the same. What is the price of this tube? One dollar per wing— that is, I mean—yes, that’s the right change. Thanks. A twist is a hinge. Yes, yes, thanks. Good night. Wilbur closed the shop in a hurry and strode home to tell his brother of the magic inherent in a pasteboard box. He had to sit up waiting until midnight, for Orville had gone to some show with his sister Katharine and one of her college friends. At last the younger brother came. Under the gaslight in the living room Wilbur twisted and twisted the precious box of pasteboard, worth half a cent as a container but untold millions as man’s compass toward flight. This was the (Continued on page 155) Some coomm ere » coverin; Auto work, how sat sb baying op Rate lip coupon for fall parte Whether you’re an_ experienced auto man or not—if you’ve just hoo! » find out AVIATI0O\ COU RS} also incly FREE : ty ExtraCha; my, yy any eips you ge good jobs. Learn how you can make real 8. Ww. 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MONEY MAKING OPPORTUNITIES SECTION 155 pebrusty, 1929

The Real Fathers of Flight (Continued from page 154) » je _, :nnortant twist in history. It became ep which in its present-day form of aileron is essential to sidewise balance of all EWi ill, I'd like to scrap with you about your 4” we can imagine Orville saying, “but it Jooks right. As you say, it makes my hinge aetical. And I guess you're on the right track with those ideas of yours on fore-and-aft ” (Meaning longitudinal or front-and- librium.) Aa a great night, which Orville doubtless ted with extra vim in his regular good- : trick of going upstairs on all fours, slap- step with his hands. Perhaps he the flourish of kicking up his heels, as, with hands on a chair, he used to do in boyish ec when reporting some invention to his ‘mother in the kitchen. At twenty-eight he was not quite grown up, and a lot of boy remains in him to this day.

LTHOUGH the brothers were now work- A ing in the bicycle shop sixteen hours a day—at least it was open to customers from six A.M. to ten p.m.—they found time to test their discovery of the twisted box. They built their first model, the first crude ancestor of the i It was a box kite or biplane with eurved surfaces and open sides, five feet wide and thirteen inches deep. Its ends could be twisted or warped in the air by means of four cords attached to the corners. Leaving Orville to tend customers at the bi- shop, Wilbur in early August, 1899, the box kite to Seminary Hill, about a from home, for its premier tryout. He was escorted by . gang of boys who oe it poe oe t fun that a grown-up man—he was Sitetwo—should fly a kite, and a very > Get My P ay - Raising Plan queer one, just for their benefit. They ran —gaiso FREE LUUUU

UUUUUUUUUU UuuUUU eR ee UUULUUUUU ee emee

—, shouted -_ — on — aie to a If You Earn | see the show. Wilbur held in ea nd a c dick with two cords attached and by twisting Less Than *70 met: the sticks he warped the corners of the soaring BE . biplane and thus guided it through the air. Smentagel a Week Write; at home.

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_| “Say, mister, it’s no good!’ shouted the boys heme. % asthe flyer ducked from side to side. _ | . . ew’ Sm er hate ee ashen rp es 198 Chteage A sadlen dive toward them, lice a hav-on a || uGhanientea’cecittaasie! | Giirkatcr ctu win bath ietnaee ‘flock of chickens, and unable to escape other- Ezeen sherk tacts pavers fate § News MRaiiniiats wise they threw themselves on their faces. Whaetanhtintol. 6 — Dobe, inser S00 on aie A definit m for getting ahead financially will be found on ESPITE some oddities in the kites con- ee nce re uct, the Wrights felt they were on their way, and the next step was to embody the 66 99 twisting principle in a man-carrying glider. OG Travel for Uncle Sam

They planned the glider that winter. Aside from their own warping device, the construc- tion or shape was that of a biplane as originated by Wenham and developed by Stringfellow and ute. This was one of many glider shapes between single and multiple wing types, none of which had any more inherent promise of ope flight than the tea kettle had prom- of becoming a locomotive. Nor were the Wrights indebted to their predecessors for curved surfaces, all of which proved to be radi- incorrect. we - With lateral balance fairly assured, Wilbur : ’ _— s a horizontal rudder to obtain fore- | fe ‘ - a ich stabilive as well as to elevate. : em mm m@ eVALUABLE COUPONa ue maw amas ruta | diveon information from the Weather Boreas | RAILWAY POSTAL CLERKS 7" “zaanetin incrirove ca Dept. L280, Roche:

FIT at perce ad it was od arg 4 as as “ ster, N. Y. Winds, suitable heights, and plenty of sand to | MANY OTHER U. S. GOVERNMENT POSITIONS ,¢ — Gus af channes Danes bei Gee ERS ease landing or possible drops from the air. $1700 t $3 400 a Year F ig of U8 Gor wt Tobe obtainable and partionars telling how te vind spring and summer the brothers ad of Railway Postal Clerk . . . ($1900-$270®) val Clark toiled at their glider in time stolen from a MEN - BOYS - 18 up a efort ome Clerk + + ss ($790-$2500) eel made brisk bicycle trade. Ash ribs were steamed to Ps .) |. See SL tiem ‘for fr | | scurve, struts shaped and fitted with a home- | Ste*4dy Work = Rapid Advancement ,¢ —_ prohibition Agent =. - - - - ($2300-$8408) — made universal (Continued on 156) Long Vacation With Pay o Siuibdenscndndgitiiedtnnieibingaeuiens at, Chieagl. ——— ex's Mail Coupon Today ActatOnce Pre aes <*., LOEE EEG PEE He a

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can | get into viation? Read this Answer from A World Famous Trans-Atlantic Pilot AVIATION is waiting for no one! Land- ing fields, plane and equipment fac- tories, air lines, service and sales organiza- tions—all are leaping ahead in the most amazi development any industry has ever known. In suc racing, feverish ner ay where is there any room for @ man who has nothi ce offer? An empty pocket- book is no drawback—but Aviation has no place, no Patience, no time for empty hands or empty heads! Aviation is taking-off for the greatest non-stop flight in history—and the men who will go along and climb to the top are the men with a foundation of FACTS under them. You Don’t Have to Fly; 40 Jobs on the Ground PAY BIG Too! To succeed in Aviation—make BIG MONEY—you need not necessarily be a pilot. There must be many thousands of pilots, cer- tainly. But for every e that files, there’s an te need for ‘tr men in more than forty different important jobs on } 3 round. Construction, motor strument — or WALTER HINTON was pilot of the fam- money. But every last one of them ous NC-4, first plane must have the FACTS. Today's problem—YOUR prob- fly the Atlantic. lem—is to LEARN Aviation i piloted the first quick. — 4 —_— _— a4 uu merica, e Get Your Ground Work poe: to fly to the waters 0 e NOW at Home— yey BE Hinton Will Train You ‘om also has the rare YOU can train at home in spare oth time. Hinton's proved course gives you all the facts about con- During struction, pastors, instruments, was a crack flyi LF of ee ation, - structor forthe o on — ‘acts ‘oday—w ith every man must have to intel course that experts | ag y and profitably fill A N agree is the most the industry. Seri 44 mplete and prac- PLR are tieal ever produced reading —Hinton is training Book shown below keen-sighted men for YOU to nave a copy too! Send the coupon NOW. etalion Institute of U. S. A. aa = WALTER HINTON, President 1115 Connecticut Avenue Washington, D. C. You Must Be 16 or Over To take an active part in Aviation you must be at least 16 years of age. If you are under 16, please do not ask for Lieut. .Hinton’s Book because it will not interest you. Aviation Institute of U. S. A. 1115 Cennecticut Ave., Washington, D. C. . Please send me at once your FREE Book, “Rich 6 Rewards in Aviation,”’ showing how I can get into ’ this tremendous field. Age (Must be over 16) i Ped So foreseen ct | MONEY MAKING OPPORTUNITIES SECTION The Real Fathers of Flight (Continued from page 155) joint so that wires over pulleys might warp the wing structure. Wilbur shopped for the sateen wing covering. They did not assemble the glider in Dayton, and planned to get some long sticks for the frame en route. While Orville stayed to tend shop for a time, Wilbur started for Kitty Hawk around Sept. 1, 1900, taking the materials and a camping out- fit. At Norfolk, Va., the pioneer found that spruce sticks were short, eighteen instead of twenty-two feet, so that the area of the glider would have to be reduced from 200 to 165 square feet. He had worse trials and tribula- tions ahead. At Elizabeth City, N. C., he en- gaged a tub of a sailboat to voyage down marshy Pasquotank River and across Albe- marle Sound. Captain Israel Perry, who was also the crew, became hysterical when they ran into a storm with loss of anchor and other gear, so that the landlubber passenger had to take charge and save the ship. it TOOK a week to make the 600-mile trip from home to the fishing hamlet of Kitty Hawk—a point on a strip of sand thrown up by the Atlan tic for many a league along the southern coast, separated from the mainland by shallow waters of Albemarle and Pimlico Sounds. The strip is one half to three miles wide. Kitty Hawk is on the landward side at one of the wider parts, six miles from historic Roanoke Island and about sixty miles north of dreaded Cape Hatteras. While setting up camp, Wilbur stayed at the home of the local postmaster, William J. Tate. One day there was a bit of dialogue like this: “May I use your sewing machine, Mrs. Tate?” “Certainly, Mr. Wright, but can’t I— “Thank you, Mrs. Tate, I can do it myself. Just want to stitch up a pair of wings.” The postmaster’s little girls shyly watched and admired the cream-hued sateen being stitched into wings by the capable stranger. I suspect they dreamed in secret envy of a better use for that beautiful cloth. Anyhow, next year the Wrights were pleased to see that the sateen, having served its first purpose, had been turned into gay dresses for the little girls. Onas joined his brother around Sep- tember 25 and they hastened to finish as- sembly of the glider. Their wall tent, twelve by twenty feet, housed the machine, a small work bench, and themselves. They had a fair array of tools between saws, vise, and breast drill, and supplies of screws, bolts, tacks, wire and strap iron, not to mention an item that they almost regarded as & panacea for mechan- ical ills of every sort from slippage to fracture. I give the reader three guesses . . . yes, bicycle cement. “Let’s try it!’ we can hear the impatient brothers ejaculate together when the glider was winged but yet lacked the front horizontal rudder. They hurried it out incomplete to a sand dune, tied a rope to its nose, and with a feverish blessing let Eolus take the steed. Hurrah! This was the reality of four years’ dreams. It rose, pranced, and danced, tugged with vicious power against the arms of its enraptured creators. What a kite—no, what an air horse for a man to mount and ride on! Now they had to ride, regardless of their set program to proceed slowly. They pulled Pegasus to earth and Wilbur stretched himself on it, face downward between wings. Orville gradually loosed the rein. It gamboled upward with almost as much vigor and steadiness as before. The man on the ground exulted. It had been his boyhood passion to fly kites and now he was flying a super-kite with his brother aboard! Science? (Continued on page 157) 9 ond deligt ted that no my oo at ant eee 7 pT Mand. Ry in Eager penn, Yoton2 Hawaiian Guitar. ‘Gurprisingts tow ctetp rh) Send for Our New Catalog Today ant sth suce you OS pee ne » ue wonder Nae y Method thod that has meant success 200 000 2 000 cathoslestio # tudents. Send for it rh while you think of it. It ie FREE. ori rehtoy, NATIONAL ACADEMY OF MUSIC Dept. 180 702 East 41st Street, Chicago { 2eth YEAR] Intensely practical training in Drafting = neering—civil, mechanical, electrical a COLLEGE —Architecture. 2-year Diploma; Degree; special short courses. Courses bal your needs. No time wasted. Instructors are e perts. 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995s Eiiz tit 5 fej ER iit E The Real Fathers of Flight ‘ (Continued from page 156) a Pshaw, this was huge fun, the greatest sport a lifetime. ; . Wilbur had another viewpoint and could not the enthusiasm of the one below. He re- pented of his rashness in wanting to ride a critter so wabbly, skittish, and dangerous. He was in the air. Earth seemed far below. In ick staccato he began to yell: “Lemme down! Lemme down! ad - The wind took his voice backward and doubtless Orville let out a bit more rope, thinking his brother was cheering and wished togo higher. Then he understood the purport of the summons and hauled Wilbur down from an altitude of something like eight feet. Lemme giro was next to ride. He went much higher and had to jump all around that bucking bronco’s back to save his neck while Wilbur ran lickety split downhill. The wild ride ended with a mild smash from which Orville rose unscathed. Repairs were soon made and the front elevating rudder was at- tached. The brothers took turns as jockeys, a halter rope still tied to the steed. Unlike their iding predecessors who used a sitting posi- tion, they rode in a recumbent face-downward , feet hooked over a rear bar as body og hips in a tight but movable cradle, -}dbows in support with hands gripping a bar ‘that moved the elevator rudder ahead. As the i le rocked sidewise its wire connections the flexible wing ends, raising one side ile lowering the other, an alternate screw action like twisting and untwisting a paste- board box. The glider was tested with varying loads without passenger and put through its paces cord control of its novel devices. When ift and drift’ were measured, the Wrights were surprised by results very contrary to ac- cepted figures. There was half the head re- sistance of framing calculated by Chanute and the lifting power was much less than the wing curve should produce according to the Lilien- thal table of air pressure. They thought per- "| haps they needed more curve and a cloth more air-tight than sateen. Could Lilienthal and Chanute together be wrong? Well, they would build another machine next year and make the wings adjustable to various curves. eeeN WHILE they moved camp four miles south to Kill Devil Hill so as to have some real jaunts on their air nag. The sand strip here is about a mile between ocean and sound. Kill Devil Hill, so-called through Indian legend, is the largest of several sand dunes wont to change their shapes by urge of Hatteras gales. It was then about 100 feet high and had a ten- degree slope northeastward. Seagulls, fish- % hawks, buzzards, and eagles sailed over the | sandy desert. Yet hoping poetically to learn something from the birds, the Wrights studied in action and carefully measured the wing spread of a fishhawk which they shot. The second day after arrival at the hill the wind fell to a favorable speed of fourteen miles an hour and they made about a dozen brief i Postmaster Tate went along to help waunch the machine. He and one of the ‘brothers—the other riding—would hold op- posite ends of the glider and run downhill with against the wind. As the biplane went free its pilot shimmied his hips to keep sidewise Dalance and with his hands shifted the forward izontal fin to maintain a fore-and-aft even It was a pleasant discovery that the pilot did not have to make a two-point landing With his feet but could make a safe stop while recumbent at twenty miles an hour. Sand flew up under the skids on landing and it was needful to shut eyes. (Continued on page 158) ts MONEY MAKING OPPORTUNITIES SECTION N NE R George Field of Pennsylvania is just a regular fellow full of pep and ambition. He wanted a bicycle, baseball equipment, and a lot of other prizes which Crowell Boys can so easily earn. George had no way of earning for himself these dandy rizes until he became a member of the Crowell Club of Junior Salesmen. He delivers in his spare time, The American Magazine, Wonsn’s Home Companion and Collier’s, The National Weekly. On every copy delivered George gets a cash commission and is rapidly building up a bank account. He is also learning the fundamentals of business and receiving valuable business experience. Lt WHY You Can Do The Same What George does you can do. Don’t wait another day to sign up with this snappy bunch of boys! Send your name rm address on the attached coupon. George Field won a bicycle like this one, as well as many other prizes selected from our Big Book of Prize.. Mr. Jim Thayer, Dept. 81, The Crowell Publishing Co., Springfield, Ohio. supply of magazines and full instructions. Dear Jim: I want to earn money and win prizes. Send me a Mail your RAEN iy 8-3. = AVIATION! NIGHTS ae OF JOY IN STORF \ Complete > TRAINING AT PARKS WORLD’S GREATEST SCHOOL! 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MONEY MAKING OPPORTUNITIES SECTION | Finish this) DRAWING (AX FINIsH the drawing of the man and girl dancing, and send it to us. It’s fun! If you like to draw, you should by all means train and develop your talent. Good drawings and de- signs for advertisements, posters, booklets, catalogs, etc., are a necessity to modern advertising, and men and women with ability to make them are well paid. Test Your Art Ability F R E E When we receive your drawing, we will send you a correct print of the complete original drawing, and also our Art Ability Ques- tionnaire. This interesting test reveals your natural sense of de- sign, color, proportion, perspective, ete. It will criticized by Federal instructors, and you will be frankly told what your score is. Learn in Your Spare Time at Home The Federal Course has. transformed hundreds of amateurs into successful Commercial Artists earning $2000, $4000, $5000, and $6000 a year,—some much more. Federal raini is thorough, practical, give you the finest of personal criticism, and brings you to the earning point in the shortest pos- sible time. Send us your drawing, and be sure to write your name, address, age and oc- cupation in the margin. Minneapolis, Minn. 1362 Federal Schools Bldg-, y The Real Fathers of Flight (Continued from page 157) The glider went forward against the wind at ten or fifteen miles an hour with reference to the ground, while it traveled at twenty-five to thirty miles an hour with allowance for speed of wind. It responded quite well to its novel system of control, that is, it kept equilibrium for a number of seconds in a straightaway flight. It went up or down with the front elevating rudder. “Although the hours and hours of practice we had hoped to obtain finally dwindled down to about two minutes,”’ said Wilbur afterward, “we were very much pleased with the general results of the trip. .. . Yet the brothers doubted that it would be worth while to return to Kitty Hawk the next year and continue their scientific sport. They had had a pleasant, exciting vacation, despite hardships of food, mosquitoes, and various other trials. They could not see a cent of profit in their work ner any notable contribution to human knowledge. Doubtless Postmaster Tate agreed with them while he computed the junk value of the glider that had been abandoned on the crest of Kill Devil Hill. He dragged it home to use as firewood and sateen dresses for his little girls to wear. Next month: More thrilling adven- tures of Wilbur and Orville Wright in their subsequent glider flights at Kitty Hawk. You'll find your interest and imagination gripped by this absorbing — of success achieved by self-taught ski Now You Can Eat Sunshine (Continued from page 48) shine in bottles as well as in packages. Strange things, these invisible rays that can give you sunburn. Under their bombardment in the dark, butter, cod liver oil, and other substances shine with a weird yellow glow, the visible evidence that their b:dden vitamins are absorbing the health zays, while other oils such as peanut oil and olive oil show snow white. Pure and impure foods may be distinguished, it has been found, by certain colors with which they shine under the wonder lamps. And one of the most important uses of all is found in the surprising ability of the rays to kill the germs that are so inimical to health. Recently an industrial process has been de- veloped to sterilize dried milk in huge quan- tities by the action of the invisible light. Butter is nowadays made germ-free by pass- ing it on an endless conveyor under an ultra- violet lamp. The water used in making one of the most popular brands of pale dry ginger ale is sterilized by ultra-violet light. It is exposed to a battery of ultra-violet lights that can handle 20,000 gallons of this widely used beverage an hour. In Great Britain sterilization of food with the rays is widely practiced. One large bakery in the north of England, for instance, exposes all its bread to the rays. For some time past hospitals have exposed all their milk to the light, which sterilizes it thoroughly and is also said to increase the content of such minerals as calcium, valuable for bone-building. These are the latest triumphs of ultra-violet light. Perhaps they are the greatest of all; for they bring the golden rays of bottled sunshine to the shadow-dwellers of the dimmest tene- ments, and to sunless inmates of office prisons in our great cities. Now everyone, by proxy at least, can bask in the sun rays that our distant ancestors wor- shiped and that our modern doctors have found so vital to health and happiness. Me U.S. “| Government 4 a Good Job, a year STEADY WORK Paid Vacation MEN - WOMEN 18 to 57 VALUABLE COUPON Mail it today SURE FREE. OF CHARGE, tis list of Doug sab t AF r a i dates, nests, etc., with sample Name ee rw er eee nn nee ewe ww www enn wennnnen, for your copy of the new Radio andbook. Shows you easy ways . Tells you how ourmen. $8.00 an hour ir spare time, jembe f hich need ets HANDBOOK 7°" “ost 70" 10 Annneent "aSe5 1ON OF AMERICA d ngineers nee d Big pay. Vaccinating wok. Quick ad- vancement. Learn at home in spare time. Personal instruction by practical men who teach for National Cash Register Co., Frigidaire, Delco-Light. Low tuition rates. Guarantee of satisfaction or money back. Free employment service. Easy terms. Write for catalog - FREE. Michael’s School, Inc., Dept. 22 , Dayton, Ohio make money taxing pictures. Prepare spare time. Also earn while you are. No exp necessary. New easy method. Nething else like Send at once for free book, O in , and full particulars. PREPARE FOR AN ART career «thru the only art school operated asa department of a large art or- ganization, who have actually pro- duced over a quarter million draw- ings for leading advertisers. Where else can you get so wide an experi- Home study Write for illustrated book telling of our successful students. MEYER BOTH COMPANY Michigan Ave. at 20th St. Dept.35, Chicago, Ill. RAISE CHINCHILLA pan East See Sidinaieet ee ies '“STAMMERI lfs Guse and You can be quickly cured if - S wo cents, coin or stamps, for 2 on Stammering and Stut te att tells how I cured myself after SENJAMIN N. tu quic! Sree} Qt EVP KB eT al instruction. 3s =e & quire * cloth bound book ttering for 20 years, Chicago, U. So &

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Eres poe a = 4 mm “EG HEE 4 Ss Batic MONEY MAKING OPPORTUNITIES SECTION At the right is a view of my draft- ing and specification offices where a large staff of experienced experts are in my constant employ. All drawings and spec- ent Law ifications are pre- My tee pared under my per- Offices sonal supervision. Just Across Street € ‘ + “ya ~ 4S ~t | - || ’ Hien ar 8 “Sith Be ie Os) Protect Your Ideas Take the First Step Today—Action Counts nventors Hf you have a useful, practical, novel idea for any new article or for an improvement on an old one, you should communicate with a competent . Registered Patent Attorney AT ONCE. Every year thousands of applica- 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 | and be entirely unknown to one another). In such a case, the burden of roof rests upon the last application filed. Delays of even a few days in g the application sometimes mean the loss of a patent. So lose no . time. Get in touch with me at once by mailing 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 law. We know the rules and requirements of the Patent Office. We can roceed in the quickest, safest and best ways in preparing an application ra patent covering your idea. Our success has been built on the strength of careful, efficient,: satisfactory service to inventors and trade- mark owners located in every state in the Union. Strict Secrecy Preserved— Write Me in Confidence All communications, sketches, drawings, etc., are held in strictest confidence in strong, steel, fireproof files, which are accessible only to authorized members of my staff. Feel free to write me fully and frankly. It is probable that I can help you. Highest references. But FIRST—clip the coupon and get my free book. Do THAT right Row. No Charge for Information On How to Proceed The booklet shown here contains valuable information relating to patent procedure that every inventor should have. And with it I will athe you CLARENCE A. O’BRIEN my “Record of Invention” form, on which you can sketch your idea and ° peng its —_ gree 2 ee Such sg may later prove valu- Registered Patent Attorney able to you. imply mail the coupon and I will send you the booklet, and . the “Record of Invention” form; together with dctiitindl tebcamaten on how on ——— ———- ea to proceed and the costs involved. Do this NOW. No need to lose a astingten, Dif. minute’s time. The coupon will bring you complete information entirely —OR— without charge or obligation. Suite 1106 Wool . vorth Bl¢ Clarence A. O’Brien Registered Patent Attorney Member of Bar of : Supreme Court of the United States; Court of Appeals, District of Columbia; Supreme Court, District of Columbia; United States Court of Claims, PRACTICE CONFINED EXCLUSIVELY TO PATENTS, TRADEMARKS AND COPYRIGHTS

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160 AMILLION DOLLAR CAN OPENER Brings Fortunes To Agents N AMAZING story of big earnings is “% being written today by hundreds of men as the result of a revolutionary inven- faon in can openers. It may seem almost incredible that this revolutionary house- hold device could sell so fast that men could double and triple their incomes in only a few weeks. Yet the cold, hard-boiled facts bear convincing proof. And now the story is ready for ambi- tious men who mail the coupon below. Nothing Like It . $265 ina It is more than just a can opener. Week It banishes all the old hard labor of ordinary can openers. It “Here is my holds the can, cuts the top out (not off) inside the rim, then flips up the lid so you can grab record for first 30 days with it. Opens round, square or oval Speedo: June cans, any size, in 3 seconds, at a 13, 60 Speedos simple twist of the wrist. Now —June 20, 84 Speedos — June 30, 192 Speedos ® Special Introductory Adver- tising Offer gives you a wonder- ful opportunity to get one for ’ —July 6, 288 your own home. It’s badly needed in every kitchen. That’s | 5?¢eds. Speedo why S io representatives of- |} ®ells to 9 out of 10 prospects.”’ ten every house on the block end make $5 every hour they M. Ornoff, Va. work. Write for Demonstration Offer Follow that hunch and mail the coupon below. It will bring you full details of our free demonstra- tion offer. It will also tell you about S ° ——, 7 ener, the equally revolutionary knife sharpener. It will show you a new, easy way to make $20 a day and more. Simply mail this coupon. CENTRAL STATES MFG. CO. Se hepee St. Louis, Mo. a) IVE ary Ave. Luxuries for the Home (Continued from page 81) walls and floor, as well as various fibers or mineral powders. One of the latter is applied with a spray gun to the walls. That is the “skin” of the modern house. And within it lie the “nerves’—an intricate system of wires and conduits, piping electricity to every needed point, from cellar to attic, that makes the 1929 dwelling preéminently an electric home. In living and dining rooms, abundant con- venience outlets along the baseboard and in the floor avoid unsightly cords hanging from the wall whenever a bridge lamp or a toaster is to be plugged in. From the wall sockets, electric clocks give observatory time. A laboratory filled with labor-saving devices is the kitchen, where electric power runs the iron, the dishwasher sink, and even, in some of the newest homes, the kitchen range. Up- stairs, the bedroom closets are equipped with switches that flash on a light automatically when you open a closet door, and shut it off when the door is closed. Convenient switches near the bed flood a room with light at a fin- ger’s touch if the baby cries or if the telephone rings. A radium-tipped screw on the switch —_ glows and helps you to find it in the ark. ODERN three- and four-way switches enable you to turn on the lights in a room from one wall switch and turn them off from another—useful in a bedroom, for in- stance, where you light the lamps when you enter and turn them off from the bed. Then there is a wall switch with a red warning lamp that glows to remind you when you have for- gotten to extinguish the lights in attic or cellar. A new two-watt lamp, supplied with a miniature transformer that screws into a socket, glows all night with a subdued light in the nursery, sick room, or bath. How is the 1929 home heated? So sootlessly that the entire cellar may become an extra floor for recreation and living rooms. The latest thing in heating, we found, is the “‘gas conversion burner,” an appliance that trans- forms your coal-fired boiler into one that burns gas. This new burner—which, by the way, looks so much like an oil burner that you might easily mistake one for the other—con- serves the heat, directing it by refractory sur- faces squarely against the side of the boiler. There are new, improved oil burner models, too, for 1929. One well-known architect told us that he never plans a dwelling today with- out making provision for possible installation of an oil burner. Evidently shoveling coal from a bin is going out of style, for now there is an “automatic furnace man,” a device run by an electric motor, that stokes your heating plant with coal continuously without attention; it removes its own ashes and stows them in a container for easy removal. FLEctTaIcrry, we learned, cannot yet compete with gas, oil, or coal for house heating as a whole. But now portable electric radiators plug into wall sockets to supply extra heat in a chilly room on very severe winter days, and in spring and fall when the furnace is not in operation. They are light enough to be carried anywhere. This year may see a fascinating dream come true—the cooling of a whole dwelling, in mid- summer, just as some of our larger theaters and restaurants are artificially cooled at present. To date, we learned, no refrigerating plant has been devised that is inexpensive enough for | the private home owner to install. But one manufacturer told us that he will place such a device on the market within a few months. It will operate, for private homes, in conjunction with a heating and air-washing plant that he already is manufacturing, and will cost about as much as the rest of the plant again. MONEY MAKING OPPORTUNITIES SECTION you. PATENTS Procured. Trade Marks Registered. —A comprehensive, experienced, prempt service for the protection and development of your ideas, Preliminary charge. 705 International .» Washington, D.C, iD, Park Row” New ¥ TRADE - MARKS NEEDED. ‘679000 Needed Inventions” Costs only $1.25 and may start you thinking the right lines. You'll get nowhere just fussing Concentrate on what the industries need, and on what the public wants. Mr. Yates’s book tells you what these ’ al. Par now and get on the right track. Outside U. S., $1406 Cash with order. ress. ureau of Inventive Science B Dept. 22 PATENTS TRADE-MARKS Without charge or obligation, we inform you on any questions you ma: put to us touching on patent, trade-mar and copyright ae b protect myself by patent, or register the trade-mark or copyright lawe? weer kind of a patent should I obtain?” and. many other questions that may oceur to These are vital points to consider and questions will be cheerfully answered. Don’t Lose Your Rights To Patent Protection Before - your invention to one send for blank fo OF eS ae to be signed and wit. | nessed. we represent hundreds of inven over the United States —s i advancement of inventions. The “Evidence of Conception,” sample, tions relating to obtaining of schedule of fees sent upon request, LANCASTER & ALLWINE Originators of forms, ‘* Evidence of Conception."* ‘TO THE MAN WITH ce ¢£ klet of information and form for disclosing idea free on request. IRVING L. McCATHRAN PATENT LAWYER Formerly with and successor to Wisner Building SERVICE You may ask: “Should I } rm “EVID As registered patent atto and Canada in the’ form: si 274 Ouray Building Washington, D. C. AN IDEA ladly furnish without Richard B. Owen New York City REGISTERED $300,000 FOR THIS INVENTION: That's what Eastman Kodak. for the Autographic idea. of other inventions are needed offer enormous 5 go for ear’ fortunes. you are of @ inventive turn of mind why not cor centrate on things that are realy md Yates’s new book. Add Rochester, N. ¥« MASON, FENWICK & LAWRENCE PATENT LAWYERS 600 F. St., N. W., Washington, D. C. Estb. over sixty years. Electrical and Chemical Inventions carefully Practice before the U. 8. Courts and the Patent Office. Prompt and careful service. Waits Us. TRADE MARKS REGISTERED Send sketches. A definite program for getting ahead financially will be found on page four of this issue.

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OPPOR PATENTS Pittsburgh, Pa., Office Chicago, Ill., Office Suite 1110 Tacoma Bldg. ? Suite 514 Empire Bldg. AND COPYRIGHTS TRADE-MARKS ¢ "¢ WS eS mS Rw sreaniee ) “ig PER yaliiey igre Bram, a7: neneeee Office a stray j s ; AP oil mae Mi Wat D.C ja, Pa., Office Suite 203 Liberty Bldg. Victor Bldg. Washington, ou nh what

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$x: Learn Piano PNA ckly by Ear Beginners and advanced students learn quickly at home—in spare time. Wonderful Niagara Method clearly shows you how. course 20 lessons. 10 years successful teaching. By R. C. JAMES How I used ee Get Icould ote down - the pine erican melody, like the jasz piano play ers Lhad heard. How I e used to wish that I cou po one in every ctowd. But I could not playa note. Niagara Method Showed Me The Way Then somewhere—just as you are reading this—I read of the Niagara Method which makes piano playing wonderfully simple. I sent for Director Wri t’s boo “The Niagara Secret.”’ I read the book, and I knew it war right. I followed Director Wright’s principles, and in no time I had caught on to his ideas. So Simple—So Easy—So Delightful And the best part of it allis that there is nothing hard about the a ae Method. In a short time, by follow- Director Wright's principles and by devoting a part my spare time to the practical application of his course, I soon learned to play. No tiresome scales—no to learn—no weary hours of ctice—no do-re-mi—no meaningless ex- eres. Ifyou ae the Niagara samet, yon os alt yn reel off any popular song which t ed o-chestra leaders play in cabarets, clubs, hotels, ce halls, or theaters. Clip Coupon Now—Play In Few Months If you have never playeda note, or if you do play— no matter how well—you too may become a master of jazz and melody by learning the simple, wonderful Niagara M wt Don’t wait another day. Send the _- coupon_now for the ““Niagara Se- ‘ cret.” This book is yours absolutely FREE, 10c (coin or stamps) is also receive wonderfu booklet**HowtoEntertain atPiano” Ronald G. Wright, Director Niagara School of Music 311 Cleveland Ave., Niagara Falls, N.Y. NIAGARA SCHOOL OF MUSIC, 311 Cleveland Avenue Wiagara Falls, W. Y. Without obligation mail me book**The Niagara Se- eret.”” Lenclose 10c for book"“How to Entertain at Piano” POPULAR CHEMISTRY POPULAR GE) CHEMISTRY A Moathly Chemical Magazine +» Latest news, experiments, formulas, recent advancements in medi- cine, new uses for X-rays, ultra-violet light, radium, etc., every month. 5. Three trial copies (back issues), 30 cents. $1.50 per year. Free solubility chart and book catalog to | di yearly subscribers. pang POPULAR CHEMISTRY aks —~_J Dept. F. D. Swedesboro, N. J. MONEY MAKING OPPORTUNITIES SECTION If You Had Millions to Spend— (Continued from page 32) studied economics, chemistry, political phil- osophy, and international law and found time to win his blue at tennis and to captain the Pembroke College team. A young fellow just turned twenty-three, the family concern sent him to Chile to develop the Chile Copper Company, a fresh Guggen- heim mining project. When he had put the business on its feet, piped water in from forty miles away, transmitted power from the sea- coast eighty miles off, set a mining town of 10,000 souls a-teeming in the desert, and started to produce more low-grade copper, at lower cost, than any other mine in the world, Harry Guggenheim felt that he could safely leave the job to other hands. In March, 1917, enjoying a short holiday in Florida, he was one of those Americans who realized that airplanes would play an enor- mously important part in the war which his country was destined to enter a month later. HE BOUGHT a Curtiss flying boat and re- ceived his first piloting instruction. Re- turning North, he organized a group of his friends into a unit of aviators, and eventually was commissioned Lieutenant, Junior Grade, in the Aviation Corps of the U. S. Naval Reserve. Soon afterwards, Admiral H. I. Cone, in charge of the Naval Aviation foreign service at the time, sent Lieutenant Guggenheim across to help organize Naval air stations. Several outstanding accomplishments abroad followed, —_—— he was active in France, Italy, and England. At the close of the war, he returned to this country with the rank of Lieutenant Commander in the Naval Reserve Corps, the United States Naval Aviator’s wings, and the Brevetto Superiore of Italy. For a while after the war, Harry Guggen- heim took part in the organization and opera- tion of nitrate properties in Chile and tin mines in Bolivia, making an independent fortune. Then he decided to bid farewell to routine commercial business for good. He had lost his taste for it. He felt that he could no longer lose himself in business and that it was no use to try. But he did know that he could lose hi '—and be happy!—in some kind of pioneering activity of broad public significance. But what? HE answer came in a meeting with Chan- cellor Ellsworth Brown of New York Uni- versity. Mr. Guggenheim was asked by the educator to assist in establishing courses in aeronautics at the institution. Here was the opportunity for which he had been looking; a service precisely in line with his experience and interests. He composed a letter for the committee in charge of the funds-raising campaign, of which he was made a member, to be sent to a num- ber of wealthy men, including his own uncles, appealing for aid in the establishment of the school of aeronautics. He did not know at the time that his letter was to raise more than three million dollars. When Daniel Guggenheim, Harry’s father, heard of the letter, he waxed as enthusiastic as his ‘son, and the next day announced that he had decided himself to endow the Daniel Guggenheim School of Aeronautics at New York University. And this, don’t forget, was long before the day when trans-Atlantic flying pam bm had converted thousands of people, young and old, rich and poor, into aviation fans. And in January, 1926, the elder Guggenheim decided to go a step further. He set aside a sum of two and a half million dollars for the endowment of the Daniel Guggenheim Fund for the Promotion of (Continued on page 163) Practical educators for all Engineers, Firemen, Machinists, Electricians and engineer students, Eight valuable, up-to- 2 date Guides treating on the theory and practice -@—" of modern ingin - ail its b ngineering in PLETE DY COURSE AND REFERENCE LIBRARY 8 pocket numbers with Ready Reference Index. 8754 pages, 4750illustrations. Easy in toread. Highly endorsed. A good securing Engineer’s License. Price bi: terms, $1 per month. Free Trial, INFORMATION: — in A Hi Form. Answers to Your Questions and Pro Here is a partial list of the subjects covered:— Engine Principies, Vaive Setting, Corliss Engines, Unifiow umping Engines, Contractors Engines, Locomotives, Marine Engines, Turbine Engines, Gas Engines, Oil Engines, in. dicators, ucers, Aviation, Steam, Fuel Economy, Boiler Constructioa, ing, Oil Burners, Stokers, BoilerR: Pipe Fitting, —-_ Refrigeration, Sita’ Elected Digtists tauis Bee > ms trical Reference and Caleu tions. SHIPPED FREE Not a cent to pay until you see the books, obligation to buy unless you are satisfied. ie in coupon iz pencil, Send now—toda this ° standard library for Engineers and M Sa oe ee ee oe ee oo oe a 4 24 2a Theo. Audel & Co., 65W.23 St,N.Y. Send me AUD G ze ILLE AND MECHANICS GUIDES. 8 numbers, $12, for free examination, { If satisfactory, I will send you $1 in 7 days, then $1 monthly until $12 is paid. ° { rain CATER RAPHE RS Y¥ soon qualify for the wonderful opportunities in this big pay profession. RA Projector GIVEN Mt alt 4 . your : Ag Business. Learn ‘at Home or in our great New N.Y. INSTITUTE OF PHOTOGRAPHY Department § . Anyone CAN LEAR NIE we w Card 5 aR ios ee EARN MONEY /MMEDI4TELY~ WE FURNISH EQUIPMENT TO START Gaitsce of PHOTOGRAPHY Earn $200 to $500 a month as photographer or developing, retouching, airbrush, e Indi methods. Big demand for our graduates. Di awarded. Nation-wide patro: now! Free catalog. Box 319, hoto-engraver. We prepare you in 6 to 8 months. — horough practical training in making negatives, rinting. to- ving in line, halftone, and 3-color work. — vidual instruction using latest equipment oma . 35thyear. Enroll fiingham, IIl.

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ry, 1995 RSE RY Eat i one Bens Pek oe B |e) SRESTER Be F SP” lithe February, 1929 ——————— If You Had Millions to Spend— (Continued from page 162) Aeronautics, and Harry Guggenheim became its president. j Now every working day finds Harry Guggen- heim busy in his office, toiling to advance the time when a winged humanity will broaden the scope of its travels and its thinking so as to include the entire world. And that day, he firmly believes, will come within our lifetime. “Qn what do you base that belief?’’I asked him. 7 “Qn the extraordinary developments now ing place in aerodynamic design and in the construction and operation of aircraft,” was his answer. ‘But to hasten the coming of universal flying, mechanical progress alone is not sufficient. The popular mind must keep with these advances; through constant education and demonstration of the safety and feasibility of flying as a mode of everyday rtation, the people of this country will have to acquire the attitude of faith, of con- fidence toward aviation. 7 average man’s attitude toward air travel today is still skeptical,” he con- tinued. “Of course, he is interested in reading of flying exploits and glad when his country’s airmen set new records. But in the back of his head there lurks a deep-seated reluctance to trust that most elusive of the elements— the air. The fury of tornadoes ashore or ty- hoons at sea, for some reason, holds less terror for him than this paradoxical business of defy- ing gravity with heavier-than-air machines. He may send his letters by air mail, but he prefers to let someone else do the flying!” This, then, in brief, is the double purpose of the Guggenheim Fund: to help solve the re- maining fundamental problems of aviation and to-overcome popular skepticism of air trans- portation. “What do you consider the fundamental flying problems that remain to be solved?” was my next question. “There are four’’ he replied. “‘The produc- tion of an aerodynamically safe plane; the fighting of fog, one of the flyer’s most merciless enemies; the development of a special aviation meteorology; and the overcoming of sleet con- ditions.” Then he told me of the great international Safe-Aircraft Competition which the Fund is now conducting to help find the solution of the first and perhaps most important of these problems. :, “But mind you,” he said, “‘that is not the only reason for the competition. It is part of our educational program as well. Through this undertaking, we hope to achieve areal advance in the safety of flying by bring- ing out improvements in the aerodynamic char- acteristics of heavier-than-air craft without sacrificing the good practical qualities of exist- ing design. But, at the same time, we expect to demonstrate that airplane travel is basically as safe as railway and steamship transpor- tation!” The competition is probably the biggest single piece of work the Guggenheim Fund has attempted. As recognized an authority as Lindbergh said of it that “it ought to result in a ship comparable to the automobile for easy and safe operation.” Orville Wright is chairman of the interna- tional contest, which offers a first prize of $100,000 and five prizes of $10,000 each for winning designs. So far, eleven entries have been made—five from this country, as ar by British manufacturers, and one from taly. “What we aim to do,” Harry Guggenheim explained, ‘‘is to encourage the development of safe aerodynamic qualities of aircraft. In accordance with the (Continued on page 164) Tower BuiLDING Chicago, Ill. MONEY MAKING OPPORTUNITIES SECTION PATENTS TRADE-MARKS , FOREIGN PATENTS MUNN & CO. PATENT ATTORNEYS Associated since 1846 with the S cientific American SciENTIFIC AMERICAN BUILDING 24 W. 40th St., New York City Van Noys Buitp1inGc Los Angeles, Cal. FRQLETD Books and Information on Patents and Trade-Marks by Request Associates in all Foreign Countries DESIGNS ScrENTIFIC AMERICAN BuILDING Washington, D. C. Hosart Buitpinc San Francisco, Cal. Box P29, Troy, Ohio ONLY $1659 MONTHLY ~ — write for SOUTH AMERICAN ““How to Apply for Position.” No obligations. 14600 Alma Avenue, Like to Travel—does Romantic, Wealthy South America call you? Unusual Opportunities for young men, Ly Employers ay farean expenses. ig pay SERVICE BUREAU Detroit, Mich. eatiatiaaied HB ONE DAY efnncine Pays $150 to $300 Monthly Profits Ascne of the oldest pat- Start your own big business now. py nat we hes oarat for. ae fy consistent charge, a radio ypatteries. vias ry terms. jae er en for cooaits, evidenced by y many well known on arantee. rite to 7 i HOBART BROS, CO Lacey&Lacey G48 FSt., Waste, D.C. keteb, 1600: PATENTS Trade-marks, Copyrights, Patent Litigati Handbook with illustrations, 100 mechani movements. Sent free on TERI ALBERT E. DIETERICH Formerly member Examining Corp. U. 8. Patent Office Registered Patent Lawyer and Solicitor 80 years’ experience 681-A Ouray Bldg. Washington, D. C. details of your inven- Send tion or patent at once, or business 30 years. Com- plete facilities. References. Adam Fisher Mfg. Co., 183-D Enright, St. Louis, Mo. BOOKLET FREE HIGHEST REFERENCES PROMPTNESS ASSURED BEST RESULTS Send drawing or model for examination and advice WATSON E. COLEMAN, Patent Lawyer Dept. 130, Terms Reasonable. Best Ref- 7 WEARER. oc cc ccccccncocccccecocsconccepngeseoueneeee erences. . : IIR. oi 0c0cccccncacennnescenssstssnnbonal Srndee RANDOLPH & CO.: ; ss icnssceckaanenane OMT: ...0skcctstennienae Washington, D.C. : 724 Ninth Street Washington, D. C. 7 NVENTORS youn we YOUR IDEAS Send for our Guide Book, HOW TO GET YOUR PATENT, and Evidence of Invention Blank, sent Free on request. our terms, methods, etc. Send model or sketch and description of your invention for Inspec- BS SSNS TR ate tion and Instructions Free. 1 Tells

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MONEY MAKING OPPORTUNITIES SECTION Revealed / superbdevelopmentofhis oo! muscle— the basic reason for his tremendous vocal power. Strengthen pour Hyo-Glossus ~and YOUR Voice will be Powerful, Rich,Compelling U have a Hyo-Glossus muscle in your throat. But you never use it because the nerve center in the brain controlling this muscle is dormant. The great secret of isolating this great vocal muscle was discovered by Eugene Feuchtinger, A. M., fa Europ musi- clan-scientist, who has now made his simple scientific method of voice development avail- able to everyone. It is ideally adapted to correspondence instruction. Theexercises are silent. You can practice them in the privacy of your own home. The results are sure. 100% Improvement Guaranteed In fact, we guarantee to refund your tuition if your voice is not improved 100% in your opinion. You alone are to be the judge. Inspiring New Book FREE You will do yourself a great and lasting by studying this book, “Physical Voice ulturs”. It may be the first step in your ca- reer. Do not delay. Mail the coupon today, PERFECT VOICE INSTITUTE 1922 Sunnyside Ave., Studio 13-62 Chicago ¥ aeneaseesy a Perfect Voice Institute ; . 1922 Sunnyside Ave., Studie 13-62 Chicago ao . EPnrsical Voie FREE I? T have pat X opposite Ps > the subject that .nterests me most. I assume no © tigation whatever. a & OCSinging C) Speaking C Stammering C Weak Voice ° 5 Nome sitll deals a # es 3 aoe : i M0 aane $ If You Had Millions to Spend— (Continued from page 163) specifications developed for the competition, the following characteristics are sought: A plane that will land more slowly; roll only a short distance after landing; be able to make very flat glides; be able to glide steeply and in safety over obstacles surrounding the field; take off quickly and on a steep path; remain in perfect control after the stall and in all other flight attitudes; and be inherently stable, when, owing to weather conditions, the pilot cannot himself maintain an even keel.’ “The plane that meets this acid test will be a pretty safe ship! It will do a great deal toward making aviation not only a young man’s game, but everybody’s game, like motor- ing. Developments now taking place strongly indicate that planes will be produced in the near future that will satisfy the requirements of our competition.” HE contest will not close until October 31, 1929, and meanwhile the Fund is marshal- ling its forces in its war upon fog. Although Harry Guggenheim is not now prepared to predict that the problem will be solved com- pletely, he is very hopeful that the gravest dangers attendant upon fog-flying may soon be overcome. The flying laboratory just established is in charge of Lieutenant James H. Doolittle, U. S. Army Air Corps, an experienced pilot of scien- tific and engineering training. Colonel Lind- bergh, consultant of the Fund, was largely in- strumental in organizing the project and acts as its special adviser. Incidentally, when Lindbergh made his fa- mous good-will tour of eighty-two cities which the Fund organized to dramatize the safety of flying, he landed on scheduled time, according to his custom, for every one of his stops but one, and in that case—at Portland, Me.—his lateness was due to fog. Two biplanes, a Vought Corsair and a Con- solidated NY-2, are used in the fog-fighting organization. Each plane is equipped with im- proved instruments designed to give the pilot his bearings in the thickest weather and to tell him his exact height above the ground at all times, thus completely robbing fog of its many perils. The fog question naturally led to the next problem—the development of a special meteor- ology of aviation. Mr. Guggenheim told me that the Fund, not long ago, established a complete aeronautical weather reporting serv- ice on the Los Angeles-San Francisco airway. In this project, the organization received the codperation of the Army, the Navy, the De- partment of Commerce, the Weather Bureau, and the telephone company. MAGINE a “main street”’ of the air, with the aerial equivalents of stop, go, and cau- tion signals, which each hour and a half, from 6:30 o'clock in the morning until 3:30 o’clock in the afternoon, receives reports from thirty- three stations in an area 400 miles long and 150 miles wide, and you have an idea of the extent and significance of this service. The stations “along the way”’ furnish infor- mation on winds, clouds, fog, visibility, and weather, which are flashed by wire to airports and fo such planes as are equipped with radio. The service is now used by several regular air- lines and a great number of individual planes. Major E. H. Bowie, in charge of the San Francisco weather bureau, is the director. Dr. C. G. Rossby, of the Massachusetts Institute of Technology, Consultant of the Fund, was prominent in organizing the work. While on the subject of the elements, I asked Mr. Guggenheim whether he felt that transoceanic flights should be encouraged. His answer was most emphatically in the negative! (Continued on page 165) February, iyy 10 Inches Of Waistline Ip 35 Days “T reduced from 48 ay to 38 inches in 35 days,” says R. E, Johnson, of Akron, O., “just by wearing a Director Belt. Stom- ach now firm, doesn’t sag and I feel fine.”’ The Director Belt gets at the cause of fat and quickly re- moves it by its gentle, kneading, massaging action on the abdo- men, which causes the fat to be dissolved and absorbed. Thou- sands have proved it and doctors recommend it as the natural way to reduce. Sto oP. drugs, exercises and dieting. Try this easy way. Sent on Trial Let us prove our claims. ‘We’ll send a Director for trial. If you dog t get results you owe Rotning. You don’t risk a penny. Write for trial offer, doctors’ en- dorsements and letters from users. Mail the coupon NOW LANDON &WARNER 332 S. La Salle St., Chicago, Ill. Landon & Warner, Dept A-9, 332 S. LaSalle, Chicag, Gentlemen: Without cost or obligation on my part please send me details of your trial offer. i i i u Name. Make Your Vest PocKeET Bring You Bb weer, ARRY this amazing new / f adding machine in your vest ‘ pocket. Make $3. 00 an hour showing it to ik ke professional men sai others. Agents cleaning up with this fast seller, Everyone we does any kind of figuring needs it and will buy on sight. Complete Adding Machine Only $2.5 VE-PO-AD duplicates Roe. of yee adding machines. Sells for only ‘a . Man! | ver had a chance to CLEAN UP BM MONEY—here it is! Sample Ve-Po-Ad vn ‘oa don’t need enogiinee, © a7 his Seet week, “yp Ones ee cel - a PoP Ade an ver, $4.09 ou" fer "Rati datal details ae f PREEV Ve a end my MONEY-MAKING PLAN. De C. M. CLEARY 173 W. Madison St., Dept. 152, Chicago, Ii, Draw Cartoons TURN YOUR TALENT INTO MONEY Cartoonists earn from $50 to $250 per week—some even mort Remarkable Circle’ System of Drawing teaches you in half te usual time. Students from all parts of the world are for this exceptional instruction. Personal criticism service * up-to-the-minute instruction make it easy for National studeai to attain success. Send for interesting BOOKLET and SAMPIB LESSON PLATE explaining full details of the Course and whit National students are accomplishing. No salesman will call. The National School of Carteveland, Ol esis eeseec® :0 mi OSS OS Fel we tener > Of h. 8 Op 615 Penton Building Se CARDS, . at.) & . ebeleted LTTE Ty | Caattins 2 Serer

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Col.Lindbergh visit “Bod” Gurney, his visits guecessor as our Chief Air Mail Pilot andInstructor. Read ted story in new book: “MAK- INGGOOD IN AVI- ATION.” Price, 25c. today. Dept. Q2. ROBERTSON FLYi Affiliated with a Making Good — ° 7 in Aviation Get this vitally interest- ing new book—full of valuable suggestions— your opportunities in aviation—your first step —how pilots and me- chanics: are trained for big-paying positions, Read the thrilling story of the days when Col. Lindbergh, flew the mails—how “Bud” Gur- ney rose from barn- stormer to Chief Air Mail Pilot. “MAKING GOOD IN AVIATION ”— containing full page photo of Col. Lindbergh and other interesting illustra- tions—sent postpaid for 25e, stamps or coin, Air Mail Pilots Teach Flying to advanced students at Robertson School of Aviation—an exclusive feature of this insti- tution, ane ofthe oldest, largest, best equipred schools in the country. Over 94 years—550 graduates—no accidents, Army School sys- tem. Ten Licensed Transport Pilots on teach- ing staff. Modern traini Curtiss-Robin” factofies on field. NG SERVICES, Inc. Robertson Aircraft Corporation Division, Universal Aviation Corp. Lambert-St. Louis Flying Field Anglum, St. Louis County, Mo. M-610 ———————— ships. “Ryan” and Write | gern 5 Af r Plan Yes om make Sharging “betters Welsh set a in his y+ 4 frent: by the next day i had made $41.50. Mail This Coupon ac. F. Bensens, Cates Snotneer Sufependent orks 5116 Ravenswood Ave., Chicago, Dept. Dear Mr. Holmes: Sure I want that book of Big Profits. Bend it to me at once. 23-62 ; H HF Name. Address ez = oe ee en If You Had Millions to Spend— (Continued from page 164) “Spectacular transoceanic flights should most distinctly be discouraged!”’ he said. “What we should encourage is the development of equipment that will -make all flying safe! Under present conditions, we are overstraining both our personnel and equipment in under- taking such feats. The splendid historic ex- ploits of Lindbergh, Byrd, Chamberlin, Mait- land and Hegenberger, Brock and Schlee, Goebel, and others were very important as a means of arousing the public imagination. But this purpose has now been served:”’ “‘And what of the future of the lighter-than- air ship?” “At the moment the lighter-than-air craft seems to offer the only practicable means for transoceanic air travel; but our need, so far as heavier-than-air craft is concerned, is the de- velopment of seaworthy, multi-engined flying boats. America, which formerly led the world in flying boat building, is now far behind Ger- many and England in this regard.” “Q PEAKING of transoceanic flying,”’ I put in, “a few women—and Miss Amelia Earhart particularly—have recently distin- guished themselves in the air. Do you think there is a future for women in aviation, or will flying always be exclusively a man’s game?” “Not at all! You see, aviation, contrary to the general public impression, is not confined to the pilot; though he, of course, dramatizes and, in a sense, symbolizes flying to the man (and woman) in the street. But don’t forget that a large ground personnel is highly essen- tial. I, for one, see no reason why women should not enter this field, as well as other industries. **And then, the airplane of the future will be just as easy to operate as the automobile of today; and, therefore, in time to come, there will be in proportion as many women pilots as there are women drivers of automobiles at present.” - you think that all people are fit to fly ” “By no means! On account of the great ex- pertness required, the potentially good pilot is the exception rather than the rule. He must be physically fit, particularly alert, possess al- most perfect codrdination, be well-trained, and have long experience. But these requirements are bound to be eliminated in the future by the greater simplicity and safety of aircraft.” UNDREDS of young men are deeply in- terested in aviation as a career, a fact attested to by numerous letters of inquiry re- ceived daily by PoruLtar Scrence Monruaty. For that reason, I next asked Harry Guggen- heim to give his views on this subject. He told me that, aside from its endowment of the School of Aeronautics at New York University, the Fund has made grants totaling almost $1,200,000 for laboratories, equipment, and experimental studies to the California In- stitute of Technology, the Massachusetts Insti- tute of Technology, Leland Stanford Univer- sity, the University of Michigan, and the University of Washington. In addition, it has financed other educational work, including lectures on aeronautics and the publication of technical papers. And re- cently it organized a committee of eighty mem- ‘bers, whose task is to solve the problem of aeronautical education in the primary and secondary schools throughout the country. “That will give you some idea,” he smiled, “of the extent to which we are interested in aviation as a career for young men! In fact this was the outstanding reason that prompted my father to endow the Fund. ‘The future expansion of aviation will natu- rally depend largely on the character of its personnel, Young (Continued on page 166) Decorate these Giftwares as we will Earn money at home, this fascinating new way, in spare time We Show You = How HIS is the most delightful work you could imagine; you will enjoy every minute you de- vote to it. Many people do it solely for the artistic pleasure they get in ereating beautiful things. But it also pays surpris- ingly well, |for there is an enor- mous demand for giftwares. Many of our members make $10 to $25 a week and have built up profit- able businesses from small begin- nings. Think of decorating a Hanging Shelf, for example, re- quiring only 3 hours work and realizing a profit of $10.50. What other work could be so inter- esting and pay so well? No Special Ability Needed The’ national association of homeworkers known as Fireside Industries now has open- ings for new members. This is your oppor- tunity. Find out how you can secure a mem- bership. The work is easily learned, and easy to do. . ; You have only to follow the simple direc- tions given by Gabriel Andre Petit, the Art Director, and you can easily learn the latest methods of decorating wooden toys, parchment lamp shades painted furniture, book-ends, greeting cards, batik and other objects of art. You are furnished a complete outfit of materials, worth $10.00 without extracost. You can start mak- ing money almost at once, Money-Back Offer What thousands of others are doing in Fireside Indus- tries, you also can do. So sure are we of your success in this fascinating work that we refund your money in full if, after completing your instructions, you are not entirely pl You take no risk whatever. Beautiful Book FREE The beautiful Book of Fireside Industries,illustrated in color, explains all about this new way to earn moncy at home. It will be sent you, absolutely FREE and without obligation. Just mail the coupon, or write, enclosing 2c stamp for postage. But do this at once, while openings for new members are being offered. FIRESIDE INDUSTRIES Dept. 51-B, Adrian, Mich. Fireside Industries, Dept. 51-B Adrian, Michigan Please send me, Free, the book on Fireside Indus- tries, which explains how I may earn money at home. I enclose 2c stamp. > (Write in pencil—ink will blot)sssssssssseed

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“I wish [ had his job” “He hasn’t been here nearly as long as I have, but he’s earning three times as much. Seems to me he’s the first man the firm thinks of whenever there is a good position open. Always makes good too. I wish I had started studying with the I. C. S. when he did.” Are you just wishing for a better job too? Are other men getting the promo- tions you'd like to have? Are you letting the precious, priceless hours slip by unimproved? You know as well as we do that ycu’ve got to /Jearn more in order to earn more. And you know, too, that the best way to learn more is to take up a course with the International Correspondence Schools and study in the spare time that most men waste. Isn’t it better to start today than to wait a year or five years and then wish you had? Mail the coupon for Free Booklet “INTERNATIONAL CORRESPONDENCE SCHOOLS “The Universal University’ Box 7614-F, Seranton, Penna. Without cost or obligation on A please send me @ copy of your 48-page booklet, “‘Whe Wins and Why,” and tell me how I can qualify for the position, or in thé subject, before which I have marked an X: BUSINESS TRAINING COURSES Business Management Business Correspenderce Industrial Management ()Show Card and Sign Ae - mR States a anagemen mograp! ccounting and C.P.A. English Civil Service Coaching st Accounting Railway Mail Clerk Bookkeeping Mail Carrier sretarial Work _JCommon School Subjects Spanish French LJ High School Subjects Salesma iD Tilustrating [()} Cartooning Advertising Lumber Dealer TECHNICAL AND INDUSTRIAL COURSES Architect Automobile ——_ Architectural Draftsman[ Airplane Engin Building Foreman Plumber and Steam Fitter Concrete Builder Plumbing Inspector Contractor and Builder ‘oreman Plumber Structural Draftsman Heating and Ventilation jeet-Metal Worker gi Refrigeration Engineer bt ghway Enginee a Geamioey i] rmacy Mining Engineer _JNavigation () Assayer Saaggag 3 = Rem 3 3 Machine Si LJIron and Steel Worker ‘maker | Textile Overseer or Supt. ternmaker _JCotton Manufacturing Civil Engineer LJ Woolen Manufacturing Surveying and Mapping see O Fruit Growing ‘ou Gas Engine Operating rok a Badio Ti achtnsinemacaseenapets - Street Ts bickéssonessungeaicodecsonccscens Ti inteetddecesccccnscscvdueience State Si iitirh nk eink i ces nansthangesuninbaasancénbeonscnesteageengeneseecneen tion tf you reside in Canada, send this coupon to the Guternational Correspondence Schools Canadian, Limited, ’ Montreal, Canada MONEY MAKING OPPORTUNITIES SECTION February, 19 If You Had Millions to Spend— (Continued from page 165) men who have had their imaginations kindled by the astonishing achievements in aviation in the past two years have been eager to take advantage of the opportunity which its rapid commercial development offers. “We, too, receive numerous requests from young men for information concerning the training and the demand for mechanics and pilots. In order to answer these questions in- telligently, the Fund not long ago addressed a questionnaire to operators of air transport companies, executives of aerial service com- panies, and aircraft manufacturers to ascertain to what extent a trained personnel is needed and to discover the best methods of supplying it. ** And this is what we found: The air trans- port companies that answered our question- naire stated that most of their pilots were high school and college graduates with aeronautical training. When these pilots were employed, they already had an average of more than 1,000 hours of flying each to their credit. Five hundred hours of flying is the minimum re- quired of new pilots by the air transport companies. “Most pilots, they wrote, received their training in the regular Army or Navy or in the Reserve Corps. A few gained their expe- rience in the commercial field. But the most desirable experience for their pilots, as the companies see it, is a combination of Army and commercial training. “It developed that practically all aircraft manufacturers employ graduate engineers in their engineering departments. But while a technical education is deemed essential, only a small percentage of the graduate engineers employed had pursued specialized courses lead- ing to a degree in aeronautical engineering. “Yet, the demand for young men with highly specialized training is apparent, for the answers showed that, in employing additional personnel, the preference is given to graduates in aeronautics. “The replies revealed that aeronautical graduates are especially needed in engineering departments where a knowledge of draftsman- ship and structure is desired. For positions such as shop foremen, previous aircraft manu- facturing experience is the most important requirement. On the other hand, for the higher positions a specialized education is a necessary qualification.” Here Are Correct Answers to Questions on Page 56 1. Aside from the stars and planets we can see, space is strewn with countless smaller bodies varying in size from that of an apple to the mass of a mountain. When these bodies, traveling at enormous velocity, strike the earth’s atmosphere, the friction immediately raises their temperature to incandescence and we see them as shooting stars. 2. The sun, an incandescent body, radiates light of all colors, which, together, make white light. But each of the gases around it absorbs one or‘more of the colors, so that there are hundreds of dark bands in the spectrum. comparing the location of these bands in the spectra of the sun and other stars with the bands produced by known substances found on earth, it has been assumed that the stars are made up of about the same materials as our own earth. 3. The distance to the nearest celestial body, the moon, is measured by simultaneously ob- serving the angle to a given point on the moon from two widely separated points on the earth’s surface and then solving the triangle thus formed by the aid ‘Continued on page 167) —_ In the Grand Central\Zone Hotel Montelair Lexington Avenue 49th to 50th Sts. NEW YORK CITY Just_Completed.and Opened! 800 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 i S. Gregory Taylor, President Oscar W. Richards, Manager CODE TRAINING At Home Has Helped Many Radio elegraph 810 E. 39th St., Brooklyn,N.Y. Learn Cartooning At Home—in Your Time The famous Picture Chart Method of teaching original Ce has opened the door of success for hun- dreds of beginners. Whether you think you have talent or not, send = sain me chart to test your abil- examples of the work of $50 to $300 eek. Please state your age. THE LANDONSCHOOL 1451 National Bidg., Cleveland, 0. Make Secret Investigations Earn Big Money Work home or travel Particulars FREE. Write: Dept. P. S. AMERICAN DETECTIVE SYSTEM 2190 Broadway triat; ‘amonth ifsatistied. Theo. Audet & Co., 65 W. 23d St., NewYork, Dept. £28 \ = He of 1 SEER “ €&S2SSBE2a™ BESSaSS gE 2¢ BS488° ESESRTE S-SReesg yr Sessee SeScseEs £82238 SBers ©

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ed! aths r q| E Een (co Nhe EZ si ag 3355 Arh f ? gebruary, 1929 MONEY MAKING OPPORTUNITIES SECTION escizethe Correct Answers to Questions on Page 56 (Continued from page 166) ‘«onometry. The distance to the sun is oe in a the same way, by sighting the planet Venus as it passes across the face of the sun. The stars similarly are measured, ysing the diameter of the orbit of the earth, 136,000,000 miles, as a base for the triangle. 4. Science knows more about. what comets are not than about what they are. Large num- bers of these mysterious celestial visitors revolve about the sun as do the planets, except that the comet’s path is a tremendously elon- gated ellipse. Some of them are true sky wan- derers. They may appear, circle around our sun, and then wander off to visit other uni- yerses. ‘The comet is not solid. Even the bright- est and most substantial looking part is thinner than the thinnest part of our atmosphere. 5, No form of life known to man could exist fora moment on the moon. It is a completely dead world. It has no atmosphere nor any water, two essentials to life as we know it. The larger planets—Neptune, Uranus, Saturn, and Jupiter—are still partly gaseous and life on them is inconceivable. There may be veg- etation on Mars, and some form of animal or even human life is a bare possibility. Venus may be inhabited. If it is, the life there may resemble the life on this earth as-it was count- less ages.ago when dinosaurs flourished. It seems logical to assume that outside of our own solar. system, there must be countless planets, circling around other suns, that roughly duplicate the conditions on earth, and that life on these planets could exist. 6. The moon is far smaller than the sun, and so when the: moon passes between sun and earth, its shadow is cone shaped. If the moon were smaller or farther away the apex of the cone of shadow would not touch the earth, and a total eclipse would be impossible. 7, The relatively thin ring about the planet Saturn probably consists of a swarm of mete- orice stones rotating about the planet just as does the moon about the earth. The ring is approximately 3,000 miles wide and the inside edge of it is more than 80,000 miles from the 8. No one knows what is beyond the stars. The infinity of space seems to be beyond hu- man conception. Even the fact that our most powerful telescopes reveal areas where nothing can be seen is not sure proof that there are no stars there. There may be stars so far away that their light rays cannot be detected. 9. While the stars are invisible to the unaided eye in the daytime, they can be seen through & telescope. The blue light of the sky during the day is sunlight reflected from the atmos- a. It is so bright that it obscures the stars. there were no atmosphere, the sky would appear just as black in the daytime as it now at night. Without atmosphere, the sun would appear as a fiery red ball floating in a sea of blackness dotted with stars. 10. While the stars appear to twinkle, the light from them is absolutely steady. The twinkling is caused by the refraction produced y air currents in our own atmosphere. If the atmosphere were still and of uniform tem- perature, there would be no twinkling. Trap High-Flying Insects PNSEcT traps attached to airplanes have found the pink boll weevil moths and other injurious insects, at altitudes and distances viously unsuspected, investigators of the U.S. Department of Agriculture working with Mexican officials, report. : planet. It is not more than 200 miles thick. 1 THIS MAN 1S MIAKING lo oe? Sharpening Lawnmowers in Spare Time With the ‘Ideal’? Lawnmower Sharpener Man, Why Don’t You Do That? You've got the chance—the same chance as W. T. Moore, Twin Falls, Idaho, who made $1200 sya in 90 days—the same chance as Walter Wever, Middletown, N. Y., who made > $1000 in 4 months—the same chance as hundreds of others who have reaped rich rewards with this amazingly effi- cient lawnmower sharpener. Use Your Spare Time. If you work at a trade, put an Ideal in your basement and earn $4 to $6 an hour evenings and Saturday afternoons. E. W. McCormick, Segenew, Mich., writes: ‘‘Five years ago I bought an Ideal Sha ener on which I have ground over 5,000 lawnmowers. In the — few —_ + — at 4 trade, — re | time ours a day. I also groun mowers which nett: $2.00—d upon the charge you fix. Per) No training required, and machine set upin me $114.10 clear gain. a few minutes. Plug into light socket and _ You Make Money Right Away. Geo, E. Kearney, start to sharpen. Stillwater, Minn., writes: “We set the machine up 2 weeks Hundreds of dull mowers in your locality o Friday; since that time have sharpe mowers.” eR ng Ay? Ee = hy erat That's close to $200 in Kearney’s pocket for 2 weeks work! No town too small, R. S_ Newcomer, Our Free Book Tells You How these men and many Vinton, Ia., writes: “People come from Others have made themselves independent—built sub- miles around and other towns to get their stantial permanent BIG PAYING businesses with this Ideal Grinder. Send for this book teday—lIt’s free. — a oe * Ideal = me | e year round, too. arpens skates—a! kinds—perfectly. The Fate-Root-Heath Co., 933-956 Bell St., Plymouth, Ohio, U.S.A. SIGN THIS AND MAIL TODAY C. 8. Coburn, Little Rock, Ark., =a writes that his “Ideal” Sharpener 2 \ The Fate-Root-Heath Co., Mower slips into sharpener without being dismantled. The “Ideal” Lawnmower Sharpener is a wonderfully simple machine that sharpens makes of mowers perfectly, scientifically without taking the mowers apart. Just pick up the mower, set it in the ‘Ideal’, make a few simple adjustments and proceed to sharpen. In 15 minutes the mower is ready for the a any you have made $1.50 to earned enough in 18 months to pay for itself and $1857 worth of weeks. L. W. Huston, Falls City, Nebr., writes that his ma- chine paid for itself in one month. FREE book fel/s\* how others do 1£,/ A definite program for getting ahead financially will be found on page four of this issue. : VEST POCKET SIZE AREAL JOB . Waiting forYou in DDS, SUBTRACTS, 2 # 933-956 Bell St. § Plymouth, Ohio. Send me the book that tells me how I can make my ' spare time worth $4 to $6.00 per hour. + LTIPLIES, DIVIDES Does work of a machine. Guaranteed 5 ears. NOT A LA Made of steel and indestructible. Million dol- mistakes,” "So. simple’ child, can ‘operate It, can . for figuring. es. So simple cl should carry hi one back. 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