Popular Science Monthly 1930-04: Vol 116 Iss 4

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——r fy | “April | : 1930 25 cents |i . ¢Hto to Get into if il Ghiding~ ‘page <i

Fortunes that Farm ih % Throw Away |

+ Are You Fit to Drin Hi Your Car? (8 ee fF | or tying if by Assen Jordano i i Amazing Machines Run a Great na . By 55 Eminent Men: | | Will Our $10,000 Priaii Stimulate Science? ‘ nee Ae ¢

Explore Mysterious 1 Island of the Dead \ BS Hy ‘4 ¢ | ‘ ij wv ' : «) ~ Radio ~ ~Automobiles~ The Home Worksho Pi je *¢ Pig + ’ te V/ j } f ' | {

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s With the warm spring sunshine, the daffodils and the violets, the fresh green grass and the singing of happy birds, each year comes “Rogers” time. It is the time of new life and new beauty—when the urge to clean up, to erase the smudge of a long winter, is in the air. Then, Rogers Brushing Lacquer, the modern “quick-action” finish, is the first thought in millions of homes. For to ' them “Rogers” stands for new color and new beauty ‘—easily applied and quickly dried. Try “Rogers” in your spring cleaning and decorating. See how easily it works. Easier to apply than ever before Anyone can beautify with “Rogers.” No experience is needed. No expert brush work is required. Merely flow on the bright, beautiful color with a full brush. Like cream, it spreads—quickly levels itself out. Then . it forms a durable lustrous coating of modern color over old or new sur- faces, of wood, metal or glass. YOU MERELY FLOW THE COLOR ON **Money-Back” Guaranty Try one can of Rogers Brushing Lacquer. If not more than satisfied, return what is left to your dealer. He is au- thorized to refund the entire purchase price. | It’s ‘Rogers time again in millions of homes cr. es eo ° ci ~ # ] bw? OF 7 ~ * » ¥. cays BRUSHING LACQUER The natural, quick-action finish for the home vce Dries fast—but not too fast Rogers Brushing Lacquer dries while you wait—yet is easily handled. Dries smooth, free from ugly laps or * brush marks. Dries before dust can mar your work. Dries to a porcelain-like hardness that cleans easily— that wears and wears and WEARS. A new “Rogers” for Linoleum This is a clear, colorless “Rogers” lacquer which forms a tough, long-wearing, transparent coating over your linoleum. Protects the surface. Makes cleaning easy. Enhances beauty of design and colorings. Easy to apply. Dries ready to walk on in about an hour. Try it. 26 colors—at leading dealers “Rogers” comes in 26 beautiful modern /acquer colors, also black, white and clear. Sold by leading paint, hardware and department stores everywhere on the “Money-Back” Guaranty printed here. Insist upon the genuine in the familiar “Oriental” can. Distributed and Guaranteed by: ACME WHITE LEAD AND COLOR WORKS, Detroit, Michigan; DETROIT WHITE LEAD WORKS, Detroit, Michigan; LINCOLN PAINT AND COLOR COMPANY, Lincoln, Nebraska; THE MARTIN-SENOUR COMPANY, Chicago, Illinois; PENINSULAR PAINT AND VARNISH COMPANY, Detroit, Michigan; THE SHERWIN-WILLIAMS COMPANY, Cleveland, Ohio; THE SHERWIN-WILLIAMS CO. OF CANADA, LTD., Montreal, Canada; LEWIS BERGER AND SONS, LTD., London, England, and Syd- ney, Australia; THE SHERWIN-WILLIAMS CO., London, England, and Sydney, Australia. fo

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APRIL, 1930 POPULAR SCIENCE MONTHLY There is extra value in good used cars bought from reliable dealers ' | ‘HE growing popularity of cars that have passed from the hands of their first owners is not the result of any sudden necessity for purse pinching. It is due entirely to a rapidly increas- ing realization that a used car, when properly selected, is a good buy, offering advantages that are not to be ignored. Thousands of business and profes- sional men, as well as women from all walks of life, have discovered this fact and will tell you there is sound common sense and true economy in the purchase of a good used car. Some of them looked at the matter this way: Before they bought a used car they had no car at all. They were without personal transporta- tion in a day when an automobile has become a necessity. They were not yet ready to lay out the money required for the new car they had in mind, but they knew they could buy a used car for far less than that amount and for J Womens ' less, even, than any new car costs. And so they bought a used car, being careful to buy a good used car. Others have purchased used cars because it meant they could thus own a car of higher quality, and therefore, one yielding greater per- sonal satisfaction, than the same money could command in the new car field. It is pretty safe to say that the vast majority of these satisfied used car owners observed certain precautions in making their purchases. The rules they followed are simple. They picked reliable dealers with an established new car business—men with reputations to conserve and good will to preserve. Many of these used car buyers have selected and continue to select Cadillac-La Salle dealers, because these thoroughly reliable merchants sell new cars of the highest quality and have been chosen to carry out the policies of Cadillac and General Motors. The very nature of their new car business means that their used car stocks are likely to offer an excep- tional variety. It means, also, that every used car offered is reasonably priced. To get the utmost value in good used cars we suggest you visit the used car department of any Cadillac-La Salle dealer. If it happens that he has not in his own stock the particular car you are seeking, he may be able to secure it for you. CADILLAC-LA SALLE CADILLAC MOTOR CAR COMPANY DETROIT, MICHIGAN Division of General Motors OSHAWA, CANADA

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25 Cents a Copy $2.50 a Year Pop pular Science 381 Fourth Avenue New York, N. Y. MONTHLY unded 1872

Table of Contents for April, 1930

LEADING ARTICLES 7 Astronomy = Wilk Comet Parades bef Fortunes That Farmers Throw Away .By E. E. Free 19 bee Toaas — 7 nd 46 Why waste is the Liggest problem of agriculture Chicago’s Planetarium Nearing Modern Hotel Isa Huge Machine . . . By Alden P. Armagnac 22 Completion soe ee ee 50 A glimpse of the mechanical servants the guest never sees A bil How to Get into Gliding ; ; . By Edwin W. Teale 24 utomovtles Expert advice on breaking into a thrilling sport Handy Pressure Gage Fits in Languages Now Taught by X-Ray By George H. Dacy 26 May = Garbage rok... ~ Strange new facts about the way we talk Front-Wheel-Drive Truck . . 3] Explore Weird Island of the Dead By Michel Mok 27 A Limousine Side Car. . . . 33 How science is seeking the key to a Pacific mystery mab — re Bete — 33 What Our $10,000 Prize Will Do for Science 40 Fumes . . » Ce Distinguished men comment on the Popular Science owned New Headlight Tester. . . 33 Tests Auto Drivers... 33 How Air Camera Men Map Unseen Places Queer jobs a pioneer aerial surveyor has done First Photo Took Eight Hours; Now—20,000 in a Second . By H. C. Davis The romantic story of Daguerre, father of picture-taking Are You Fit to Drive Your Car? Harbors for Motor Boats ; How cities are planning to shelter small craft . By Charles F. Keale, Jr. 42 . By Robert E. Martin What new psychological tests reveal about the man at the wheel . By George Lee Dowd, Jr. 57 Speedy Tank for Smashing Attack 35 Chemist Fights Deadly Gas . . 35 Wheel Alignment Measured . . 35 44 Acetylene as Auto Fuel . . . 35 Chalk Line for Autos ._. 62 Women Drivers Expect Too Much 55 Courtesy ? . . 5 cents. Yearly su wg - United States, its possessions, and Canada, $2.50; heosien countries, $3. contents of this magazine must not be reprinted without permission. The editors are not ss for unsolicited cont cmucions, and cannot guarantee the re- turn of such material or insure against its loss. In presenting numerous stories of new products of applied science, poeeee Science Monthly does not under- write the business methods of the individuals or concerns roducing them. The use of ~@ ivi. —— Monthly articles for 6 schemes is never authori pen, President and Treasure Cc. Wi ilson, Vice-Presi- dent; A. L. Cole, vice Preckdont and Secretary.

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Popular Science Monthly for April, 1930 Sun Baths for Miners. . 51 Biue Aniline Dye Now Used in Fight on Cancer. . . 52 Laboratory Discoveries New Gravity Standard for United States... Powerful Ray Tube to Bombard the Atoms. 38 Analyzes Third of a Dro 50 Finds Protons Play Dou bie R Role; Wins Prize . . 50 Models Electricity Runs Model Steam Locomotive .. tae 64 Ship Model Carries Crew. . 67 How to Make a Railing for a Mo- tor Boat Model ._. 7 Stagecoach Model Making t.*s, Building a Model Glider ._. 82 Model Plane Flies Too Fast for His Camera ; . 114 Nature Bees’ Tongues May -Yet Prove Acquired Traits Persist. .. 52 Birds is Foretell Spring Better Than Men 61 “ Nightmare” Animal Dotes on ggs 62 Plant Poses as Snake to Trap Live a Serer aes Only Four Animals Outlive Ma. 66 An Arctic Scene in New York . 67 New Processes and Inventions New British Locomotive a Stream- lined Giant. - 2). ae Lens Invented for Panoramic Movies. 29 Tool Combines Square, Cc jage, Plumb, Level. . . New Core for C astings 30 Harden Steel by New Magnetic Process. 30 Numbered Keyboard an Aid to Banjoists .. . Switch Controls High Voltages . 3 A New Coke Dust Fuel . 32 Printing Fine Filigree on Rubber Mats . 32 Invents Combination Globe and Atlas . rae Mail Box Tells Weather ee 34 Finger Moistener, in Palm, Helps Clerks. . 36 New Device Supports Bike in Traffic 36 Section Freight Car Cuts: Loading Time . 37 Motor Takes the Place of Pin Boy 37 Handy Bracelet Serves as Maga- zine Holder . 38 Novel Lip Form Just Stamps the Rouge On 38 New Composition Hard as Flint, Flexible as ool 46 “Ice Fans” Cool French Railway COM... 4 46 Radio Noctovision Tested for Ships Lost in Fo gir 200, Wr Oo ite oe Half of World’s Radio Sets in America . 38 Wireless Plan Proposed Nearly 60 YearsAgo .. . 64 1 4 a b Radio Condenser Capacity Test . 72 eYerr Aid Partly Deaf . 72 sof Radio . . . 2 Ships Aircraft Carrier’s Power Lights City fora Month . 45 Winged Boat to Try to Cross Ocean . 61 New Italian Steamer May Beat Bremen _. ‘ 61 Barge Is a Counterweight . . 2. Unusual Facts and Ideas Makes “ Artificial Air”’ for Planes and Subs... 32 St. Louis Botanists. pete Sun- shine... 36 Nonpoisonous Dyes Now Paint the Lily .. 36 Proof of Parentage Is Found in the ood . — Refueling While the Race Is On . 37 Fish Now Travel in De Luxe Car. 37 Pawpaw Tree Furnishes Food, Soap, Medicine . 38 Shoot Poison Dust to Kill the M itoes . . oe What We Burn U Every Year . 39 Rhythmic Noises Speed Up Work- er’s Output. 45 Nation-Wide Surv ey to Fix Exact Locations. . 45 How Much Do You Know about Physics? 46 ‘Spinning Wheel” Bottles Ger- man Soft Drinks. . 46 A College for Police... . 47 School for Rescue Squads in Abandoned Mine . 48 Is There a Limit to the Size of Hailstones? . 48 Studies Eskimo and Indian to Trace Kinship. 48 Priest Explores Alaskan Volcano. 49 Predicting Thunderstorms . 50 Ocean’s Floor fs Classroom for Undersea Zoologists 52 Machine Measures Thought but Is No Mind Reader _. 52 Ancient Swamp Village Found in Sweden 61 Women Still Beat Men in Tests of Emotion . 62 $20,000,000, 000 in Gold Mined in 400 Years. : & Danger Lurks in Liquid Steel . 63 Crane Accidentally Lifts Engine . 63 Not Much of a Rocket. 63 Find Tomb of Ancient Scythian Chieftain . 64 —es Adds Thrills to Sea port Towers Peek Through Sea of Fog 66 Roman Gods Found in Old German Wall. . 66 Government Comes to Antelope’ s Rescue. ahi¢@ Building Their Own Abbey — For the Home Owner Stand Converts Hose into Garden Sprinkler. . 107 Rubber Band Helps Start Nails in Awkward Places ._. 109 Bringing the Wall Switch within Child’s Reach . 114 Stopping a Leak in a Hot Water Storage Tank. . 117 Electric Fittings Designed to Do Double Duty . ; . . 118s *¥ Casting Concrete Stepping Stones inthe Ground. . . 123 Installing Closet Conveniences . 126 Woodworking Making a Convenient ne Cabinet... .) et 9 ae Finishing the Seascoot. . . . 88 Magazine-Rack End Table. 96 Lightweight Sewing Stand Has Roomy Compartments . . a Craftwork A Quaint Old Candle Lantern. . 81 How to Make an Embossed Leath- er Trinket Box . 98 Making a Balancing Gander of Wood . 103 Miniature Pirate’s Chest Built to Hold Jewelry _.. . 104 Decorative Glow Lamps . . 106 New Finishes for Woodwork . . 108 How to Whittle a Toy Seapl . 110 Homemade Lathe for aking Deadeyes . 112 Hints on Building a Small Game able. . 116 Block Puzzling—the latest Craze . 127 An Escape Trick and Envelope Mystery for Amateurs . . . 128 Ideas for the Handy Man How to Build a Sturdy Saw-horse. 84 Rubber Ball Saves Sliding Door from Slam 84 Varnish Sticks Cloth to Desk Top 102 Where to — for Other Mechani- cal Art 103 File-tolding zie Has Cloth Com- 107 F ed Pa Paper Airplane Explodes on Landing 110 Blueprints for the Home Work Shop . 111 Accurate Jointing with Hand Plane and Guide ___.. 115 Glass Jars Fastened under Shelf to Hold Hardware . 117 Easy Method for Bending Large Diameter Conduit. 120 Simple Tool Facilitates the Driv- ing of Nails . 120 Simply Constructed Rack Holds Fishing Rods A + op ae Cheap Self-F. eeder for Pigs . 131 Chemical Crack Fillers and Wood Stains . 132 . 136 Molding a Concrete | Roller for Lawns. . Hints for hd Mechanic More Ways to Put Wire to Work 92 Dividing Work in the Lathe . . 94 Old Bill Says— 94 Chucking a Paper Friction in the Lathe . 110 115 120 122 Turni Heavy Pipe Bends in a Smalf Lat ee Tool Made from Discarded ali : Increasing sg Life of Form Cut- ting Tools. — Small Holes with Ver- or Callens I Roller Sup Saw Stock. Steel ee Simplifies Structural Layou Remedeling a Tool Grinder to Do Tap Fluting . Tapered Keys Accurately | Ground in the Miller. . rt for Power Hack 127 133 135 a ee aaicecteneaid centers ey ae

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4 Ketire in l 5 Years on your Present living Budget by investing in safe 612% First Mortgage Bonds Follow the definite plan given in the new edition of this famous book, and your financial independence is won. The plan works just as surely whether you are now earning $1,000 or $100,000 a year. The way is certain—each step plainly in- dicated and absolutely safe—independent of luck, business genius or speculation. Every fact has been harvested out of the 48 years’ experience of Cochran & McCluer in the first mortgage investment banking business. The plan is so simple any one can under- stand it—so definite any one can follow it—and so certain no one can fail. In addition to the Financial Independ- ence Plan and the unique budget sched- ule, the book gives suggestions that en- able you to enjoy more of the good things of life, both while building your inde- pendent fortune and after you have at- tained it. We invite the most skeptical to read this lain, straightforward, interesting book. hone, call or send coupon. We employ no salesmen, therefore none will call. MAIL THIS FOR Please send me, without obligation, ! a copy of the new edition of your! famous book, “How to Retire in! 1% r Cochran & McCluer Co psma} ? ' 46 N. Dearborn St., Chicago } ! ] 15 Years. = i Cochran &M“Chuer Established 188 1—Never a loss to any investor 46 North Dearborn St., Chicago, IIl. ' trolled stock market | of bitter memories. Do You Know How To Get Year-Round Comfort With Fuel Saving? If you are building or modernizing your present home, Popular Science Institute recommends that you look into the matter of insulation. Complete facts on this with figures on fuel saving, data regarding efficiency of different insulating materials, and advice on best methods of applying is contained in the 24-page booklet “Insulation in Build- ing Construction.” Price 25 cents. Popular Science Institute 383 Fourth Ave. New York POPULAR SCIENCE MONTHLY APRIL, 1930 ‘Stock Dividends Will Make Money Grow Faster By CHALLISS GORE, Financial Editor OU remember y the day—the 16-million share day on the Stock Ex- change. The pro- longed and uncon- crash had swept a multitude of dream castles into the limbo It was on the 5:36 train in the evening of that day, October 29, 1929, that I first took individual notice of Sid Grimm. He was an exception among the men on the train. His interest in shrinking security values was but casual. Had Sid been shrewd enough to sell out before the | break? Was he playing the short side of the market? Had his broker neglected to send the dreaded margin call? “What’s your position in this market?” I ventured to inquire. “Just what it has been right along... sitting on the side-lines . . . watching... | envying at times... but spending no ‘paper’ profits...and in the last few days suffering no losses.” “How did you resist the market lure?” “The temptation was pretty strong at times,” he admitted. ‘For the past few years, particularly this year, most of the men in our office had me dizzy with their | accounts of speculative profits. Now they are all wailing over their losses. Through- out the entire bull market I stuck to my determination to. play safe with what money I had saved... with the result that I still have it.” “You are fortunate,” I observed. “Very few men tonight are enjoying your freedom from financial worries.” “Freedom from financial worries. . . bah!” exclaimed Sid. ‘I haven’t been playing the stock market but I have my money troubles.” My inquiring expression invited Sid to explain. “My income is increasing a little each year... 1 have a small stake tucked away . . . and manage to add to it bit by bit as I go along. “But... with a growing family... three youngsters now . . . expenses going up ...it’s hard to get ahead very rap- idly. I’ll never be independent on what I can save out of my salary. I’ve got to find some way to make my capital grow faster.” “Why not re-invest your dividends and make your investments grow that way?” I suggested. “You know if dividends are re-invested money piles up fast.” “Like everybody else,” explained Sid, “T usually anticipate the receipt of the dividends and have a need for it... taxes, insurance premiums, house repairs, a new piece of furniture, or something else. Furthermore, the dividends are small... not easy to re-invest alone... A Suggestion to Those Who Are Growing Faster Than They Are Getting Richer and if I hold them in the bank until I have a sizable amount they usually disappear.” Older Sid had suggested an interesting prob- lem... one which is perplexing many a conservative investor. Salary savings alone are usually insufficient to gain financial independence. Speculating for a rise in stocks usually ends up in losses and always distracts one’s mind from his work. Re-investment is sound in theory, but often fails in practice, as it had with Sid Grimm. And of course many inves- tors are not financially able to re-invest all their dividends and interest. One very practical answer to this com- mon problem is an investment stock which pays dividends both in cash and in stock. There are a number of such stocks which are entitled to a rating as a sound investment. The combination of cash and stock dividends provides three im- portant advantages to the investor: 1. A regular income in cash; 2. A steadily increasing cash income; 3. An investment that grows in value, independent of any advance in market price. The key to the whole situation is that portion of the dividend which is paid in stock. After payment of each quarterly dividend the investor owns more stock, and draws greater future dividends. Under this plan re-investment is taken care of almost automatically. The com- pany simply takes a portion of the earn- ings available for dividends, invests in new stock and distributes that stock to shareholders. In paying dividends in this manner it is necessary to issue scrip cer- tificates to represent fractions of full shares. An investor may hold these frac- tions until they equal a full share, when they begin to draw dividends, or he may purchase additional scrip and thus al- ways keep his holdings in full-share units. The benefits of the cash and stock dividend policy may be illustrated by the following table. I have taken as an example a stock selling at $50 a share. This stock pays a quarterly dividend of 50c a share in cash and 1% in stock. This is am annual divi- dend basis of 4% in cash plus 4% in stock. I have assumed the initial purchase of 20 shares of stock at $50 per share—total cost $1,000. (1) The first dividend on the investment in 20 shares would be $10 cash and 2/10 of one share of stock (1% of 20 shares.) By the additional purchase of 80/100 of a share the investor would own a total of 21 shares. Therefore the second dividend would be $10.50 cash and 21/100 of a share (Continued on page 6)

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Apri, 1930 POPULAR SCIENCE MONTHLY THE METAL THAT 18 24 IMPORTANT POINTS HIDDEN “TUNED” IN THE BOTTOM OF YOUR RADIO CABINET Take your radio out of its cabinet, turn it upside down, and you will see a dozen or more fixed condensers. (The photo above gives an idea of where they are.) These are the points where most radio power failures occur. Make sure the fixed condensers of your new radio are made of Alcoa Aluminum Foil. Then you can buy with greater confidence. The high electrical conductivity of Alcoa Aluminum Foil minimizes power losses. It is extremely light in weight, reducing strain within the chassis. Alcoa Aluminum Foil is just pure aluminum—rolled into sheets as thin as paper—and yet the foil re- tains the strength, durability and non-corrodible qualities that are the outstanding characteristics of Alcoa Aluminum. Alcoa Aluminum is used for many other radio parts—condenser blades, shielding, wire and cast parts. Look for the many Alcoa Aluminum parts in the chassis of the next radio you buy; their presence means the power, the tone-qualities—the se- lectiveness that you seek. ALUMI- NUM COMPANY of AMERICA; 2496 Oliver Building, PITTSBURGH, PENN- SYLVANIA. Offices in 19 Principal Ameri- can Cities. TO RADIO 4 B ALCOA ALUMINUM FOR RADIO i} } + ‘| a + it ; . smn eet op hts = . —- se eee PON ioe ee ee ee pS? Samet eee a ex i f ee ee Ce en ee

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PUT ASIDE 54 CENTS A DAY —FOR $2,500.00 OU’LL never miss this small amount; one fine day you will have $2,500—or more—cash in hand. It will seem like finding the money—it will do some wonderful things for you and yours. More than 165,000 people use the Investors Syndicate pian. Let us tell you about it. Return this ad- vertisement with your name and address for payment schedules and full information. RESOURCES OVER $32,000,000 INVESTORS SYNDICATE FOUNDED :1894 MINNEAPOLIS NEW YORK LOS ANGELES OFFICES IN 51 PRINCIPAL CITIES Why Some are Wealthy Many are those who see in a dollar only what it will buy. But some view a dollar as a seed from which, when planted in the fertile soil of good first mortgage bonds, future dollars will spring. For this reason, some are wealthy. If you would be sure of a comfortable future, invest a portion of your income now in Fidel- ity 6% First Mortgage Real Estate Bonds. The rate of return is good. Each bond, being se- cured by a conservative first mortgage on some new, income producing property, your investment is safe beyond question. In addi- tion, the payment of both principal and in- terest is guaranteed at maturity. Permit us to send you without obligation, a copy of our booklet, “Your Money —Its Safe Investment,” together with a list of available issues. 4.U.MENTEER .Proident oe INCORPORATED 195 660 Chemical Building, St. Louis 1188 New York Life Bldg., Chicago 378 Colorado Nat’! Bank Bldg., Denver NIOOt OL MARE EII POPULAR SCIENCE MONTHLY APRIL, 1930 Stock Dividends Will Make Money Grow (Continued from page 4) of new stock. Repeating the purchase of a fractional share, the investor’s third dividend would be $11 cash and 22/100 shares; the fourth dividend, $11.50 cash and 23/100 shares; and so on. Over a period of time these tiny increases have a very substantial effect on the amount of the cash income and the value of the investment. The following tables show what happens during a 10-year period. In this way small savings from salary are put into additional stock purchases and the stock dividends are also saved and it is easy lo make your money grow. TABLE A How Your Investment Grows At end of| Dividend} Shares | Total | Total Am’t | Total Years Shares |Bought|Shares| Invested | Value 20. 20 | $1,000.00 |$1,000 1 .86 3.14 24 1,118.50 | 1,200 2 1.02 2.98 28 1,269.50 | 1,400 3 1.18 2.82 32 1,412.50 | 1,600 4 1.34 2.66 36 1,547.50 | 1,800 5 1.50 2.50 40 1,674.50 | 2,000 6 1.66 2.34 | 44 1,793.50 | 2,200 7 1.82 2.18 48 1,904.50 | 2,400 8 1.98 2.02 52 2,007.50 | 2,600 9 2.14 1.86 56 2,102.50 | 2,800 10 2.30 1.70 60 2,189.50 | 3,000 In this 10-year example the investor | triples his holdings... from 20 to 60 shares. At $50 each, 60 shares have a value of $3,000, but they cost only $2,189.50, so there is a capital gain of 37%, amounting to $810.50. Dividing the total cost, $2,189.50 by 60, the num- ber of shares owned, the average cost of the $50 shares is found to be $36.49. TABLE B How Your Income Increases At end of Dividend Value Average Years Cash | Stock | Total Annual Yield 1 $43 $43 $s6 8.12% 2 51 51 102 8.40% 3 59 59 118 8.68% 4 67 67 134 8.95% 5 75 75 150 9.21% 6 83 | 83 | 166 9.49% 7 91 91 182 9.65% 8 99 99 198 10.05% 9 107 107 214 10.34° 10 115 | 115 | 230 10.66% Tables A and B are figures on the as- sumption that the market price of the stock does not advance at all, but re- mains stationary at $50 a share. Without the benefit of any market rise, or any increase in the dividend rate, the in- vestor’s average annual yield on his cap- ital increases from 8.12% to 10.66% in ten years. Dividends paid in stock have been responsible for a gain in value amounting to $810.50 and an increase in total dividend value from $86 the first year to $230 the tenth year. Purposely the factor of market price advance has been ignored in Tables A and B to illustrate how investment cap- ital may grow of its own momentum... pulling itself up by its own boot straps, as it were. Of course the market price of any good stock should advance consider- ably in ten years. To illustrate how the investor additionally benefits when his se- curity advances in market price we pre- sent Table C. This computation shows the comparative position assuming a nominal price advance of % point or 50c a share each three months. . Status if price Status if no - TABLE C : advances 34 point price advance quarterly Total value in ten years.| $3,000.00 $4,200.00 Total amount invested.| 2,189.50 2,443.25 Total Capital gain... .. 810.50 1,756.75 Percentage gain....... 37.01% 71.90% Total Dividend value, first year........ ; $86.00 $87.10 Total Dividend value, | eee ee 230.00 274.30 Income yield, first year 8.12% 8.21% Income yield, tenth year 10.66% 11.57% Ten year aggregate of cash and stock divi- RRS IF $1,580 00 $1,768.15 Perhaps the most impressive feature of Table C is the total capital gain. An in- vestor who becomes impatient when the market price of his stock does not ad- vance by leaps and bounds might be surprised to know that, under such cir- cumstances as just outlined, a 2 point rise a year means $946.25 to him in ten years (the difference between $1,756.75 and $810.50). Aside from capital and income gains, there are other advantages to the inves- tor in dividends paid in stock. They en- able a growing company to increase its working capital without the expense of a special stock offering. And the less paid for working capital the more net earnings there are for the shareholder. Before a company can issue bonds or preferred stock it is necessary to have an adequate amount of common stock outstanding. An advantage of bonds and preferred stock is that they provide working capi- tal at a fixed cost, usually at a lower cost than common stock. When a company issues common stock as dividends it is constantly in position to raise cheap money as conditions warrant through preferred stock and bond issues. This strengthens common stock earnings. But the conspicuous advantage to the investor of dividends paid partly in stock is that his re-investment program is taken care of for him . . . to his own gain. To Help You Get Ahead Tt Booklets listed below will help every family in laying out a financial plan. They will be sent on request. 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. How to Retire in Fifteen Years is the story of a safe, sure and definite method of establish- ing an estate and building an independent in- come which will support you the rest of your life on the basis of your present living budget. Write for the booklet to Co¢hran & McCiner Company, 46 North Dearborn St., Chicago, Ill. How toGet the Things You Want tells how you Can wse insurance as an active part of your een for getting ahead ioancialie. Phoenix utual 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. rite for this booklet to Investors Syndicate, 100 North Seventh Street, Minneapolis, Minn.

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30 OEE SOS Oa Slti‘( ’COté«s ApriL, 1930 POPULAR SCIENCE MONTHLY Founp--- Ess than three years ago a row L of glow tubes sat in a test rack before a window in the Westinghouse research labora- tories at East Pittsburgh. D. D. Knowles, research en- gineer, glanced at them one morning and noticed that some of the tubes quite unexpectedly were glowing, while others were not. Some tubes glowed when the sun was shining and went dark on cloudy days; others responded when a hand touched the glass. It was quickly recognized that an important new electrical development had come to light. Thousands of tubes were made and tested. Shapes of various parts were altered until a relay was available—so sensitive that a tiny pulsation of energy, less than that expended bya fly walking on a window pane, was made to control enough current to operate machines rated at thousands of horsepower. Thus was born the grid-glow tube. Aan z = BS =~ Westinghouse {ff} Electrific aton Appliances Because of this development a hand waved lightly over a crystal ball in New York City started giant motors in the Homestead Steel mills hundreds of miles away. Aladdin’s lamp, which had to be rubbed to get results, is outrivaled by the grid-glow tube which responds to a mere wave of the hand. To magnify human capacities is the daily work of the West- inghouse organization. In research, in the design of elec- trical and allied equipment, in the application of electrical power to new tasks, in the distribution of electrical appara- tus for homes, business, and industry, Westinghouse is constantly active... to the end that electricity may continue in countless ways to help you get more for what you spend of time, money, and energy. a way to improve ELECTRIC POWER BUILDS BUYING POWER Westinghouse

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Automobiles and Accessories Pace Cadillac Motor Car Company.............- 1 ES. ou dase hae s cache tes 135 ee Se eee 160 Houde Engineering Corporation............ 83 Oakland Motor Car Company............-- 15 Studebaker Corporation of America, The... . 91 Aviation American School of Aviation............... 148 aS EE OY Sees Pee eee 145 Tye > errr rr eres 121 Goebel School of Flying, Art.............-- 150 Lincoln Airplane & Flying School........... 146 Universal Aviation _Schools............+++- 101 Books SE S”sCE EMEA ERE CCC 154 BE, oc ccccsscetooes 123 | mana eg Britannica, Re ree 9 I OEE Bsc cc cc cctcccccccecsces 149 Ronald cakes nabs unre cccheeee 149. Science News-Letter... 0.0... c cece eees 154 Building Materials ers... sandenahes 132 Celotex Company, The..................5- 18 Insulite Company, The.................... 87 International Mili & Timber Co............ 131 TOD GEBUNPARIOR. . ow. ccc ccccccccccs 13 Business Opportunities Central States Manufacturing Co.......... 140 «cc cccccccecceevcsse 145 Foley aE = 120-138 Kriss Kross oe neekeubune ean 155 ca cc cccccssacdicnscese 144 EE a id n'y 606666 64k ROnO es 147 National Sales Mfg. Co................... 146 Beweoomer Associates. ...............000: 144 R&B ware Oe \ Sse RSS Spe red Rollo Specialty Co., The............-...... ee ars 665 cbse nb ncedeeeeess 152 General sa. cca cssanceerdents 159 Silent Automatic Corp.................... 107 Western Electric Comeeey RRS «LADS OE 11 Westinghouse Elec Pe ee 7 Hardware Supplies Boston Varnish Company................. 113 Casein . Co. of America, The........... 126 Detroit ite Lead Works............. 2nd Cover Ey fairs wane chee e6 ds 0000.00 118 By ce ead dsc adbacdenses 125 | oes a I ds eid alba eae 00 a4 an SSS rer eee 13 Smooth-On Mig. Co 4 a ee ee 116 Industrial Equipment BING, oc ccc ccccccccsccccce 128 i Rs 56 de che 6-45 ceva eas 128 re 89 es ba ons ndat caresecsene 10 Taylor Instrument Companies............. ee Ce ad a hese tues ceded 158 Investments Goatees GO BeCimer Co. .. occ cccccccccce 4 Fidelity Bond & Mortgage Co.............. 6 I, Cia 6 paw dccacebcscnes 6 Miscellaneous ce teRi ates ke cndeccescees 110 Bureau of ee Science. 155 TR. 6 os Fonccccadevesacece 138 eS ooo iie'n asncdcctocebeeds 142 oda 6 cae wecabeeee 134 —tn Vulcanized WPT oo ect ceccce 128 ie ad Gu. s.da ken aon bene 120 Pamonth mck Squab gehen eee ayaa tae 133 eh ke 606s Ch erenneséennce 116 cha nceesnecnecdbscese 120 IIE OD oc cc ccccccscccececes 116 Musical Instruments her Band Instrument Co............. 126 } vn y= o.% OR TE Ea is MUIR, GE, Sa ccaccesanececccccccad Pan American Band Instr. & Case Co. 150 eet ea AObs ew kne screen POPULAR SCIENCE MONTHLY INDEX es Guaranteed Advertisements

Patent Attorneys Page a NNO oon cc ccccessecesesscs 154 ES RE ee rr 152 Evans & Company, Victor J.............-. 153 Fisher Mfg. Company, Adam.............. 152 CS alg goss ohh 0 6ba eee miele 152 ac bvece Ma seme seedeunesneeze 152 on neal ada Saiki Oa Mee OSE ET 152 RANROES Gh EER «oi occ cecceccecscecese 155 McCathran, Irving L.. .........cccsceeees 155 Se, GNINOD Bh... wo ccc ccccccccccecve 151 RRO Bh COURMIIG «o.oo c 5 sic ccccccceseese 155 0 "=e ee eee 152 Popular Science POPULAR SCIENCE MONTHLY guarantees every article of merchandise adver-: tised in its columns. Readers who buy products advertised in POPULAR SCIENCE MONTHLY may expect them to give absolute satisfaction under normal and proper use. Tools, Radio Apparatus, Oil Burners and Refrigerators ad- vertised in POPULAR SCIENCE MONTHLY have been tested or investigated by the Popular Science Institute of Standards and each advertisement carries the insignia indicating ap- proval. However, other products advertised in the magazine not subject to test carry the same guarantee to readers as products tested. THE PUBLISHERS Radio Apparatus Aluminum Company of America............ 5 Amperite Corporation.................... 128 I ig 6 gia add Aiglk hig & abd. 00:8 eaneects 138 Hammarlund-Roberts Mfg. Co............. 134 National Carbon Co.............. 97-137-3d Cover Radio-Victor Corporation of America....... 85 Razors, Toilet Artieles, Etc. American Safety Razor Co................. 96 Autostrop Safety Razor Co................ 104 Meme GOTHOORCIOR,. «ow cic cccnccccone 116 conta 6 Ok 6 WE Se 5s he caed anaes ae d 111 Lambert Pharmacal Co................... 17 IN ko ck dclgic ceddavddscouse 118 aie ds 4 eas 4.606 eas eon ace 105 III 5 5 kk occ ccccsiccccecocses 158 I Wig UND Be BBs aici ccceicvdccicpeces 115 Schools American Sch. Mech. Dentistry............ — 9 — eae 145- iss-137 Etiss Miectrical School. .................. Re 140 Burns School EET ae 140 Chicago Technical College................. 142 Columbian Correspondence College......... 142 Coole School of Elec., L. L................ 143 Coyne Electrical School eee 140 Detroit iy PU od vce cctevcss 150 eee ib ok 6.6:00:00.06:006.00 147 Federal School of Illustrating.............. 154 Federal School of Commercial Designing.... 157 Finlay a aT 1 APRIL, 1930

Schools (continued) Page LSE TE RT 143-147 Hamilton Institute, Alexander............. 14 International Correspondence Schools... . .142—152 Landon School of Cartooning.............. 150 La Salle Extension een BES ote — Lederer School of Drawing. 142 McCarrie School of Mechanical Dentis try.. 156 MicSweeney School... .)..........cccccccsece 149 Motion Picture Operators School........... 146 National Electrical School............... 155 National Poultry Institute... ............. 140 National Radio Institute.................. 144 National School of Cartooning........ Faciceags 149 New York Electrical School, The........... 146 New York Inst. of Photography . er 142 North American Sch. of Drawing. Dates caus 140 Watteream Gebool. .. |)... 2... ccc cccccccces 152 Radio & Television Institute............... 141 ee eee 139 hool of Engineering of Milwaukee......... 144 Standard Business Training Institute...... 144 : < _ oerbi Se eke tar aes 143 Tri-State cit cln ag’ + Shae oe eamedeaie 140 University of Chicago...............0e000. 143 A On OSS a ee 149 Utilities Engineering Inst................. 149 Smoking Materials Brown & Williamson Tobacco Corp......... 108 I gi Sle ain he idl bb os dows Back Cover Larus & Brother Company................ 98 Sporting Goods and Toys Automatic Rubber Co..................6. 147 Boweget Rammer Ce. |... cccccccccccccece 158 Harley-Davidson Motor Co................ 127 Hildebrandt Co., John J................... 124 Indian Motorcycle Co................20005 99 Johnson Motor Company.................. 109 ES SS eae errr 126 so ors ds 6a: hid ar carwre Rigas euheckers 132 ee es GN GS... on cece ccccccecces 135 Thompson Bros. Boat Mfg. Co............. 126 Things to Make American Chime Clock Co................. 133 OE" SE a ere 145 Craftsman Wood Service.................. 126 Ideal Aeroplane & Supply Co., Inc.......... 132 Miniature Ship Models, Inc............... 128 Model Ghip Supply Co... .... 0. ccc ccc ccccs 114 Schiercke, Henry C. |... ccc ccc ccc cece 120 Tools and Shop Equipment Arkograf Pen Co....................000ue 126 ON 117 ck 8 AS Serre 114 Bridgeport Hardware Mfg. Corp., The...... 119 Brown & Sharpe Mfg. Co................. 95 Carborundum Co., The Ay eer Pee 137 Delta Specialty Company SAORI re 133 Warramd,, me.. BCGER A. . o.oo ccc ccccce 124 Foley Manufacturing BY brass, eine adtaas Seatac 120 CI Ge IS BEL ob oleic cdsiccccicdcccse 124 I ak aiid sak win ed si0ko-6-04K wm nme 128 Gilson Slide Rule Co...................... 124 ee Sa eee 114 Greenfield Tap & Die Corporation.......... 102 Eee rere 114 Jennings Mfg. Co., The Russell............ 131 Maydole Hammer Co. S| See 120 Midland Appliance Corp.................. 120 Ee II, . 5 oo ccccccsececnccies 132 Nicholson File Sgr gma Rgsesip Makes are ws 112 YS Sl 8 Se ee 103 South Bend Lat | een 135 eee SO 93 Trimont Manufacturing Co., Inc........... 134 Templeton-Kenly & Co.............cec000. 118 pS arenes 100 OE SS ere are ree 129 Woodworking Machinery Co., Inc., The..... 118

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Apri, 1930 Bring the World’s Knowledge POPULAR SCIENCE MONTHLY into your Home! Give yourself and your children this completely NEW ENCYCLOPAEDIA | BRITANNICA PEN the windows of your mind—today. Bring into your home at one stroke the knowledge, the wisdom, the practical experience of 3,500 world-famous leaders of thought and action. Give your family —your children especially —the greatest knowledge book of all times—the new Encyclopaedia Britannica. A $2,000,000 “home university” IRRESH from the presses, made new from cover to cover at a cost of more than $2,000,000, here is a Britannica that marks a new epoch in home education. Never before has knowledge been made so instantly accessible—so easy to grasp. Authorities from 50 different coun- tries write its thousands of articles— bring to your home the learning of the great universities, the discoveries of science, the practical wisdom of suc- cessful men and women in all walks of life. All the world’s wonders 15,000 superb new illustrations, many in color, give vividness and charm to the fascinating pages of the new Britannica—give you the whole world in pictures. A magic book—that’s what you'll say about this new Britannica. Now, FOR OLD AND YOUNG ALIKE Children love to browse through these fascinating vol- umes. The new Britannica assists with school work, brings out unsuspected talents, helps children “find themselves.” THE MAHOGANY BOOKCASE TABLE SHOWN ABOVE IS INCLUDED WITH EACH SET in these 24 marvelous volumes, more swiftly, more easily than ever before, — you can explore any science, any in- dustry, any phase of knowledge that you please—all without leaving your own home. Ask any question, and the new Britannica tells you the answer. Yet the new Britannica is more than a mere answer-book. It is a book of richer opportunity—a vital force for self-advancement. With the Britannica always at-hand you can make even your minutes help you to success. New opportunity for all the family VERY member of your family can find practical everyday help in this marvelous book. For men eager to get ahead it is a real aid to greater earning power. For women it is a guide in all the activ itiesof the home and every outside interest. For children it provides an end- i less fund of fascinating things to make and dao. Give yourself and your family the chance to profit by Ble e222S22 ENCYCLOPAEDIA BRITANNICA, Inc. ps M.3-F3 342 Madison Avenue, New York City obligation on my oat your 56-page illustrated booklet describing the new Britannica together with low price offer, etc, Name SPECIAL OFFER New low price—$5 down ASS production on a scale never before possible gives you these books at a third of what they would otherwise cost, for less than any wholly new Britannica in 60 years. And while this offer lasts an initial payment of only $5 will bring the en- tire set together with the handsome bookcase table to your home. You can pay the balance on one of the easiest time payment plans ever devised. Send for FREE booklet Act now! Get this NEW Britannica at the present low price. Send for our free illustrated booklet. It oe specimen pages, and color plates, a. gives full informa- tion. Fill out the coupon and mail today. Please send me by return mail, without any this modern knowledge book. A ddvrese > SEND FOR FREE BOOKLET TODAY City, ne me cn om ome oom oes ae all State alan ab aban an ab aD Gn an Gn a Gn an ab Gaal

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10 POPULAR SCIENCE MONTHLY APRIL, 1930 In the building industry, also, Alundum abrasive has secured a safe foothold. Four products known as NORTON FLOORS —stair. and floor tile, ceramic mosaics, aggregates for terrazzo and for cement, and precast treads —all trade-marked ” Alundum” —all non-slip — wear resisting because of that hard, tough abrasive known to the metal industry — users of grinding wheels —the world over. — Norton Company, Worcester, Massachusetts. Refractories~Floor and Stair Tiles Grinding Wheels Grinding Machines

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Aprit, 1930 POPULAR SCIENCE MONTHLY 11 Follow this SIGN WHEN you go to a motion picture theatre now- adays you have a right to hear the voices of your favorite stars reproduced with full justice to their artistry. Fortunately you can do just that— provided you select a theatre which displays the “Western Electric equipped” sign. This apparatus reproduces speech and music in natural tones because it was Wester. SOUND| OF ACTION and hear Talking Pictures that sound NATURAL . . . designed and made by the world’s acknowledged lead- ers in the science of sound — Bell Telephone Labora- tories and Western Electric. It is the result of an experience of over half a century in making telephone apparatus that reproduces the voice with naturalness, For thorough enjoyment of your talking picture en- tertainment, look for the Western Electric sign. “WE/ectric VOICE — BY THE MAKERS OF YOUR TELEPHONE SYSTEM ._.-

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a 12 POPULAR SCIENCE MONTHLY APRIL, 1930 More Comforts for the Home New Methods in Heating and Ventilating Are Now Available to All House Owners Whether Their Buildings Are New or Old ECULIARLY fortunate is the man who is building a home today. He has at his disposal, as the result of scientific advance in construction, elaborate means for making his dwelling comfortable. Nowhere is this more apparent than in the matter of heating and ventilation. The owner of a home already built can also avail himself of these improvements. A compar- atively small expenditure often will modernize a system of heating and ventilation and pro- vide the many benefits auto- matically enjoyed by the new homebuilder. It is because experts now realize the importance not only of heat, but of other essential factors, that this revolution has come about. The result is appar- ent in new and improved methods of supplying heat and ventilation and in other modern aids to comfort. Heat, in winter, is one of the things that makes a house com- fortable. By modern standards, a heating system must deliver heat when and where it is wanted, with little fuss or bother, and at a mini- mum of expense, for a wasteful heat- ing plant has no place in the modern scheme of things. Moreover, heat today means controlled, even, adequate warmth at all hours, and there is no excuse nor necessity for putting up with less in this age of comfort. But the thermometer is not the only gage of comfort in the] house. Dry, stuffy heat is especially bad. Furniture dries out and cracks, veneering comes loose, and the irritating effect of extreme dryness on throat and nasal passages ren- ders the occupants particularly subject to colds and throat infections. The proper degree of humidity, on the other hand, gives the air freshness and vitality. En- gineers have learned at last to go Nature one better, and to provide ways within a home for controlling humidity at will. Such things as fresh air and refreshing breezes also have their place in home comfort. It is no longer necessary to re- gard these things in a hit-or-miss way. They can be provided for in the design of a home along with its heating and ven- tilating equipment. ITH modern means to control tem- perature, humidity, and quality of air, the home dweller today is better off in his house than former kings in their pal- aces. Courtesy of National Warm Air Heating Association Just a touch to the thermostat and the temperature of the home is quickly changed. One of the modern ways to home comfort. He can make his own weather to order and, so far as external conditions go, he can be as comfortable as he pleases. The advance in the design of house- heating equipment has been so rapid re- cently that many people arenotacquainted even with the major developments. Much has been done toward perfecting warm air, steam, vapor, and hot-water systems. Radical changes in the design | INSTITUTE BULLETINS House Heating and Ven- tilating* Insulation in Building Construction* List of Approved Tools List of Approved Radio Products List of Approved Oil Heating Devices Advice on Installing Oil Heat Refrigeration for the Home* *25-cent charge for starred bulletins Ot em . ~ 2 5, eV VOL AT ‘ This is the way it used to be in the long winter fight to keep comfortable. of radiators, made possible by the substitution of lightweight = metals for heavy cast iron, have Bi vastly improved the radiation - efficiency of radiators in proportion , to size, and indicate that the evolution of heating apparatus is by no means at anend. Growing use of oil and gas as fuels, together withawider application of thermo- static control of heating, have made homes much more uniformly livable than they have ever be- fore. OR the benefit of the home builder or owner who has nei- ther the time nor the means to find out for himself the advances that have been made in _ heating and ventilating equipment and their individual applicability to his problems, Popular Science Institute has conducted a survey of the entire field, putting all the data obtained in a book- let which has just been published. This booklet describes modern ways of heat- ing and ventilating, together with the principles on which they operate and the best ways of securing good results from them. In presenting this information, it has been the aim of Popular Science Institute to outline the merits of modern systems and devices in such a way that the man who is building a new home or modern- izing one already built will have a com- prehensive knowledge of just what is on the market. The information given is sufficiently complete and specific to provide a basis for an intelligent decision. For example, the three chapters on fuels give in detail the advantages of different grades of coal, oil, and gas, together with information on their relative cost and the proper methods for obtaining the best results. Besides this booklet on ‘House Heat- ing and Ventilating” (available at 25 cents a copy), the Institute will gladly supply readers with any additional or special information they require on this subject. Address: Popular Science — 381 Fourth Ave., New York, ee ee

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Aprit, 1930 The “Show Boat” — and work boats, too, are made of PRESDWOOD The romantic period in American history, when show boats carried entertainment to towns along the Missis- sippi, is faithfully portrayed in the Universal Pictures’ production, “Show Boat.” But there is just as much romance back of the industry which contributes to the advertising and production of the play itself. In a thriving Mississippi town, wood is blown apart and rocess which oards called Masonite Presdwood. And it is this readily worked and easily painted material which is so successfully used in re- pressed together again in a seg makes the grainless wood producing the “Show Boat” pictured above. Does not crack or splinter This workability of Presdwood has also led to its ex- tensive use for set construction in Hollywood studios. For Presdwood does not crack or split. It does not splinter. It is dense and smooth, and so tough and strong that the same pieces are used over and over, in set after set. perme semengens Dept. D-4,111 W. Washington St., Chicago, Il. Please send me, Free, a sample of Masonite Presdwood and the | Presdwood booklet. Name Address lose Mi POPULAR SCIENCE MONTHLY But Presdwood’s “marine” uses are not confined to the “Show Boat,” as evidenced by the Presdwood ferry boat built by John H. Parmalee, prominent Nashville architect. He proved, as have many boat builders, the ability of this grainless wood to resist moisture and withstand the hardest usage. Panels homes—lines concrete forms Presdwood provides beautiful paneling for homes, smooth lining for concrete forms. It builds incubators and iceboxes, kitchen cabinets and breakfast nooks, aisle runners and dance hall floors. It makes show window backgrounds, motor truck paneling and out- door signs; makes things better, lowers their cost. If you manufacture in ony or make things at home, a should read the Presdwood booklet. It is sent, ree, with a sample of Presdwood, on request. MASONITE CORPORATION 111 West Washington Street, Chicago, Illinois asonite PRE SDWOOD Made by the makers of

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14 OurKea No Room for the Editor I want to throw a brickbat which I am sure a large number of your readers will agree is alright. Why doesn’t the Editor give an an- swer to each letter printed or express his views, as the case may be? There are many scientific questions and arguments raised, to which a lot of us would like to know the correct answer. Will you please consider this, Mr. Editor?—C. R. L., Fargo, N. D. This section of the magazine is the creation of Poputar SCIENCE MONTHLY readers, and belongs to them. If the Editor wished to intrude (which he does not), and offer his own answers to the questions and arguments presented, many of the interesting letters would be crowded out. As it is, we have space for comparatively few of the hundreds of fine letters received each month. Most of the questions raised in one issue of the magazine are answered by readers in subsequent issues—and better answered, in many cases, than if the Editor took a hand. From a Famous Family ON BEHALF of the Executive Committee of The Fitch Family Association of America, I desire to express our great appreciation of your article in the January, 1930, number, page 33, giving Lieut. John Fitch, Revolutionary officer, credit for the “‘ World’s first successful steam- boat.” The article entitled “Sailing down the Centuries” is in error in stating that James Rumsey exhibited a steamboat on the Potomac in 1785, but we are not “kicking” about this, as Lieut. Fitch made a successful trial with his first steamboat model in the spring of 1785. I purchased several extra copies of the Jan- uary number and sent them to friends—I also sent out about seventy-five post cards to vari- ous persons interested in Lieut. Fitch’s achieve- ment, telling them to be sure to secure a copy of the January number of the Popular ScreENCE MONTHLY. This letter is written to let you know that the F. F. A. appreciates your accuracy in giving Lieut. Fitch deserved credit for the world’s first successful steamboat.— Roscoe Conkling Fitch, Detroit, Mich. But Suppose Your Two-Shaft Elevator Broke Down? In PopuLAR SCIENCE MonTHLy is an article on the limit to the size of skyscrapers due to the space occupied by elevators. Now why not, instead of having one cage to each shaft, have several to each shaft and move them continually up one shaft, over, and down another? I have never seen a cable street car system, but I imagine a system similar to this. Instead of having a row of elevator shafts and cages, say ten, there would be only two shafts and in these ten cages, some going up, some going down, and transferring at the top and bottom. The cages would be one or more stories apart, as street cars are one POPULAR SCIENCE MONTHLY or more blocks apart. Please let me know if you think this is sensible, and if anyone might be interested.—O. L., Fort Branch, Ind. What Can a Poor Girl Do? I’vE BEEN reading all the readers’ problems in “Our Readers Say,” but I haven’t found an answer to mine yet. What do you do when the boys come to the house and, finding the PopPuLAR SCIENCE, won’t do anything but read it a M. W., Sedro Woolley, Wash. The Pleasure’s All Ours Have been reading P.S.M. since 1926. I like all the articles. Think there is no magazine on the market nearly so good. The Home Workshop is my favorite department. Please make it bigger. Have made several pieces of furniture from your drawings. They have been the means of spending many a pleasant hour and I thank you.—P. K., Mars, Pa. Ant Puzzle Solved; Now for Another Asout T. O. B.’s problem of the ant on the log: The log must turn over twelve times, re- quiring the ant to travel twelve feet around and five feet lengthwise. We have, therefore, a triangle with legs of five and twelve feet re- spectively, and a hypot- enuse of thirteen feet, the latter being the dis- tance covered by the ant. But here is one I have not seen solved: How long a_ board, twelve inches wide, with the ends cut off square, can be laid flat upon the floor of a room sixteen by twenty feet?—F. L. H., Portland, Ore. Why Not Charge Rent? I HAVE been taking yearly subscriptions of PopuLaR SCIENCE MONTHLY for about three years. It is sent to my home while I am away at boarding school. Eaclt copy, by the time I get home, has been read from cover to cover, and when I take it up to school I have to fight to keep it until I have read it myself. What am I going to do about it?—W. C. J., Annapolis, Md. Florida’s “‘Big Tree”’ In your February issue I noticed an item about a cypress tree 2,000 years old and fifteen feet in girth. Such trees are common in some parts of Florida and I, myself, have seen sev- eral this size. There is, however, one tree, a cypress, too, that I think deserves special men- tion. That is a certain tree near Longwood, Fla., about twelve miles north of Orlando, that is known to the natives as “ Big Tree” and was so known to the Indians before Columbus dis- covered America. I once asked an Indian where he was from, and he answered, “Big Tree.” This mighty tree is about forty-nine feet in APRIL, 1930 circumference, and is about sixty or seventy- five feet tall. The trunk is easily fifteen feet in circumference at the top. Some idea of its size may be gained when I say it took me seven- teen paces, stepping about three feet each step, to walk outed around the tree. If Professor Kurz estimates the age of the little cypress he mentioned at 2,000 to 2,800 years, I should, as a matter of curiosity, like to have him estimate the age of the tree I am writing about. I have heard it estimated b one who does such figuring that there is enough lumber in “Big Tree” to build three houses.—(Miss) E. L., Fernandina, Fla. Do You Agree? IN REPLY to G. N. G., of London, about scrapping the submarines, the late war demon- strated the effectiveness of the sub as an offen- sive weapon in defensive warfare. The deaths in these submarine disasters are deaths in the cause of national safety, just the same as on the field of battle, just the same as in the test- ing of any new device for public or national safety. A nation at war must and will resort to any expedient to win, especially if the odds are against them. War must and will be made more horrible each and every time it is fought. No nation, however powerful, can scrap any weapon until it has proven to be positively obsolete—unless they wish to be overwhelmed by the ambition of other nations. The only way to stop war is to make it more horrible than any man can conceive.—G. C. H., St. Paul, Minn. Bus Planes a Solution? In February Poputar ScreNcE MonTHLy you mention the difference of opinion be- tween Assen Jordanoff and O. R. Angelillo. Mr. Jordanoff claims it is dangerous to fly over a city at low altitude, and Mr. Angelillo is planning a roof airport in the heart of Los Angeles. Perhaps both men are right. My plan would be to have all planes from other cities land at the commercial airport and the passengers would take a bus plane to the roof landing field in the heart of the city. In this way only scheduled planes would land at the roof airport and private lanes would not be al- owed over the city. All bus planes flying over the city would be re- quired by law to fly at a sufficient altitude to be within gliding distance of a landing place at all times. Thus motor failure would not mean a forced landing on housetops. This plane service to the center of a city would correspond to the taxi and bus service between a railroad station and business center. —U. P. McC., Oberlin, O. It’s a Good Sign, Anyway IN ANSWER to the statement by Professor Cajori in regards to the Mexican origin of our dollar sign 1 am presenting an equally if not more plausible answer to the origin of the dollar A ac

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ree out on- fen- iths the on est- nal any are tht. any ely ned ore A. ice 10t ity ice er. Or ur ot jar

Aprit, 1930 POPULAR SCIENCE MONTHLY GENERAL MOT ORS’ Lowest-Priced EIGHT

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o< Write for an interesting booklet which illustrates and describes the design of the New Oakland Eight. *OAKLAN D PRODUCT OF GENERAL MOTORS

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a 16 sign. Originally the sign was a U with an S superimposed on it, standing for the United States. Later this degenerated to $ for the sake of saving time. Why should the U. S. adopt the Mexican sign for her own use? Also how did the P of Cajori’s explanation degenerate to the two bars? Perhaps the professor is a little preju- diced to his own race.—R. A. P., Meridan, Conn. Never Too Young to Learn ASSEN JorDANoFF hit the nail on the head when he said that “thousands of Americans under six- teen want to learn to fly.” I am only fourteen, but I have been taking Jordan- off’s advice (to learn mo- tors and familiarize your- self with the parts of an airplane, the theory C Sw? of flight, and the terms around an air field) for about two years. I have received your plans (No. 114) for a “toy air- plane cockpit with controls” and am going to start work soon. Here’s hoping for more of Jordanoff’s adventures.—W. W., Vienna, S. D. In a Nutshell I HAVE enjoyed every issue of your magazine for the last three years, and I hope you will keep on with the articles pertaining to avia- tion.”—W. S. A., Glen Ridge, N. J. I think that your earlier issues, particularly those of a year or two back, were far better. I agree with some of your readers that PopuLAR ScreENCE has too much aviation articles. Let’s have more interesting Home Workshop arti- cles.—B. M. R., Brooklyn, N. Y. I am a reader of your magazine and enjoy it very much. I am particularly interested in your models of airplanes, ships, etc.—W. B., Painted Post, N. Y. The magazine is better every issue than the one preceding.—M. A. C., Bremerton, Wash. It seems to me from a scientific standpoint your magazine should cover some of the most important matters in health building, the foundation for doing anything in life—M. A. C. N., Salt Lake City, Utah. Good for You, Parson! Despite the fact that I am a parson, I have to “fix it” (some “it’’) in our home most of the time, and I know the clever and_ ingenious ways and means and tricks and technique of fixing are to be found so graphically illustrated and explained in Pop- ULAR SCIENCE MONTHLY that even a parson can see how it’s done and do it. You are producing an indispensable maga- zine, interesting and inspiring, one that should be in every home today. For your able editors and illustrators and special writers are not only keeping us abreast of the times, but also quickening our imaginations, doing again the great work performed by the prophets and seers of old, revealing to us the glories of life that shall be!—Rev. H. L. R., Minneapolis, Minn. That Walking Fish Is Making Us Popeyed Piease tell H. W. M. that his “walking fish”? is no more than a type of newt or sala- mander. Its body structure in no way re- sembles that of a fish. It is a dark chocolate brown in color and looks like a lizard and is very sluggish out of the water. In this locality POPULAR SCIENCE MONTHLY it is a nuisance to anglers and is shunned by the small barefooted waders as the most poisonous of reptiles. We call it “water dog” owing to the resemblance of its broad head and gills to the head and drooping ears of a dog. Also its wriggling motion while crawling in the mud heightens the impression of a dog wagging its tail until the hind legs skid. Some of the northern streams of northern Ohio are lousy with them in all sizes up to eighteen inches in length. While swimming its gills spread out fan shape. It loses its canine resemblance and presents one of the most repulsive sights I have ever seen. Just a word of praise for your magazine. It’s great. I have read it for ten years and never missed an issue. The most interesting part is what the readers say, with their amusing views and arguments.—K. D. F., Canal Fulton, O. But Where Would Amos ’n Andy Come In? A LARGE and probably growing class of radio receiver users no longer listen to the radio. Except on very special occasions they do not deliberately sit down to enjoy the program. To them, a radio receiver is useful mainly as a purveyor of music to form a pleasant and stim- ulating background for conversation, reading, card games, or during the daytime for house- hold duties. They class the radio with the orchestra in a theater— an accompaniment and not the main show. The deliberately pen- etrating voice of the an- nouncer handing out a lot of blarney about soap, tooth paste, or some other common- place commodity does not make a good back- ground for anything. Someday somebody is going to invent an ultra- sensitive appliance that will instantly cut out the loudspeaker when anything except music comes through and then turn it on again after the talking is finished. Make such a device so that it would, in addition, distinguish either way between jazz and other music and it would be priceless. —B. A. W., Rutland, Vt. From a Model Maker I Note that the readers of PopULAR SCIENCE MoOnrHLY interested in ship models are to have a new treat in forthcoming numbers and that you request some suggestions as to preferences. Personally, I find it hard to choose between the Hartford and the destroyer. In fact, I hope we may have both sooner or later. I made the little motor boat that ran about two years ago for a small nephew as a Christ- mas present. It really was a beauty. I am also interested in the stagecoach model and would like to see more of that line.—H. E. H., Grand- view, Wash. Getting a Look-In By CHANCE I dropped into our public library one evening and sat at a table where there were a dozen different magazines to read. The fel- low next to me was reading a magazine for which there seemed to be a big demand. I was curious. I waited till closing to have a glance at the contents, but I had to wait three nights before I could read it. I found every article interesting. P. S. M. is something different than all the magazines in the place. I am ordering a subscription so that I can really get a look-in. —D. I., South Shields, England. APRIL, 1930 A Life-Saver on the Farm I am a farmer boy, 19 years old and just through high school. I am helping my father on the farm for a year before starting college. I like engineering and similar subjects but dis- like farming, so you can imagine a fellow gets pretty lonesome some- times, sixteen miles from a good library over roads which are impass- able much of the winter. Here’s where good old P. S. M. is saving my life. I have tried other scientific magazines, but they all seem cheap, miserable productions - compared with P. S. M. Here’s why I prefer P. S. M.: if there is anything I like to see in a magazine it’s good, clear pictures and lots of them, and of course related to the subject matter. P. S. M. has them.—J. A. M., Len- nox, S. D. Found It Here, of Course THE miniature stagecoach in the February issue of PopuLAR ScreNCE MONTHLY is what I have been looking for for some time. I was working on the Mississippi steamboat but I will drop it, start working on the stagecoach, and finish the steamboat some other time.— R. P. H., Connellsville, Pa. Wanted—A New Name for Vitamins SEEING the short piece on the discovery of two new vitamins in P. S. M. reminds me of a question. Why don’t scientists change the name of these substances? The name was originally given them because they were sup- posed to be essential to life (Latin “‘vita”’) and to be chemical “‘amines””—thus “ vita-amines.” But now chemists and doctors know that they are not amines, and that they are not necessary to life. If some substances should happen to be discovered which had the above qualities, what would become of the white elephant “vitamin ”’?—R. D. B., Middletown, Conn. There'll Be No More Peace at the Hague YANKEE talkies may be all Greek to a Frenchman, an Italian, a German, or a°Span- iard, as you say in your editorial in the Feb- ruary issue, but there are some countries in Europe where the loquacious celluloid strips from America are mak- ing an enormous hit. Recent letters and news- papers from Holland, for example, have shown me that American talk- ies are “packing ’em in” at the movie houses in the principal cities, such as Amsterdam, Rotter- dam, and The Hague. In fact, the newspapers carry plaints, very much like those heard along Broadway, to the effect that the talkies are killing the legitimate theater, and musicians are perturbed by the growing popularity of “Sonny Boy” and similar theme songs in the land of the dikes and the windmills. M. W., New York City. A Gold Mine Your Pocket.Guide to Science is worth more than the subscription price alone. It certainly is a gold mine of information. I have long been a reader of PopuLAR SCIENCE and consider it the best scientific magazine. It gets better each month.—D. W., Gainesville, Ga.

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Aprit, 1930 Once a week do this. . POPULAR SCIENCE MONTHLY Note to Medical and Dental Profession When prescribing a mouth wash for germi- cidal purposes, make certain that it isa ger- micide; and not merely a colored preparation which is only deodorant and astringent. Invigorates scalp .. . CHECKS DANDRUFF HENEVER you wash your hair—and most people do it once a week—douse full strength Listerine on the scalp either before or after the rinse. Then mas- sage the scalp and hair vigorously for several minutes. You will be simply delighted by the wonderful feeling of cleanness and scalp exhilaration that follows this treatment. Moreover, it is unquestionably one of the best treat- ments for dandruff—to prevent it, and to overcome it once it has started. Many hundreds of people have told us that since making Listerine LISTERINE a part of the weekly shampoo, their scalp has felt better, their hair has looked more attractive, and is entirely free from loose dandruff. Of course, if dandruff does get a start, it will be neces- sary to repeat the Listerine treatment systematically for several days, using a little olive oil in conjunction with it if the scalp or hair is excessively dry. Listerine checks dandruff because it attacks infection that causes it, removes and dissolves the particles of loose dandruff and heals and soothes the scalp. Lambert Pharmacal Company, St. Louis, Mo., U.S. A. kills 200,000,000 germs in 15 seconds Oe ee ae . -

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ee ee ee 18 POPULAR SCIENCE MONTHLY Nature’s Refrigerators APRIL, 1930 preserved mammoths for 350,000 years! a They’re still digging mammoth meat out of the ice up in the Arctic circle. Preserved by nature for more than 350,000 years. Overwhelmed by the softness of the ground, the mam- moths were quickly sealed in muddy tombs . . . then insulated by the frozen earth ... blanketed over with heavy sheets of ice and snow. e Down in the cane-brakes of the South, nature has pro- duced another insulation ... much handier in form than ice-sealed crypts, and better suited to modern refrigera- tion uses. Protecting the heart of sugar-cane stalks is cane-fibre When you buy a refrigerator for your home, ask if it is insulated with Celotex, for Celotex insulation insures @ constant, low temperature in your cabinet . . . shortens the running time of the refrigerating unit . .. saves ice. More than 44,000 refrigerator cars are now insulated with Celotex ... to protect the fruits, vegetables, meats and other perish- able foods that you eat ... to keep them healthfully and deliciously fresh. ... long, strong and tough ... which today is interlaced into sturdy insulating boards called Celotex! Nature surely intended Celotex for refrigerating pur- poses, because she provided it with millions of tiny sealed air cells...just the thing that is required for effective insulation against heat. Industry long ago discovered the value of Celotex as refrigerator insulation. Ninety-one per cent of all railway refrigerator cars, built in a single year, have been insulated with Celotex. Thirty manufacturers, including several of the leaders of mechanical refrigerators and ice boxes, use Celotex. Celotex helps to keep your vegetables — field-green and crisp... your fruits firm and delicious... your other perishable foods sweet and fresh. It is nature’s own refrigerator insulation. THE CELOTEX COMPANY 919 North Michigan, Avenue Chicago, Illinois In Canada: Alexander Murray & Co., Ltd., Mont- real, Sales Distributors ee hout the world. Reliable dealers can —_ # elotex Standard elo Building Board an tex Lath. P The word CELOTEX site (Reg. U. S. Pat. Of.) — BRAND ey —— > INSULATING CANE BOARD The Coletex Company NATURE’S OWN REFRIGERATOR INSULATION — Me tats me im , ae a se) eee ee ee ee

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o r Ss 35 Ce MONTHLY TRAVIS HOKE Editor Prosperity shines upon the farmers ihe grow fruit, since chemists have found a use for so many of their by- peoilacts that now nothing is thrown away as waste. Markets have been developed for the juices, oils and acids extracted from the pulp and then the pulp is sold as stock food. Capitalists Are Betting a Million Dollars That They Can Stop Waste and Save the American Farmer A corporation, capitalized at that amount, was recently or- ganized to put cornstalks, the chief agri- cultural product of the United States, to industrial uses. Millions of dollars’ worth of cornstalks are discarded as waste by the farmers each year. The, new organization, formed after years of scientific research, mainly con- ducted by Professor O. R. Sweeney of Iowa State College, is backed by a group of distinguished agricul: uralists, business men, and financiers. Its principal pur- pose will be the “development of processes of converting cornstalks into thin lumber substitutes of low price but good quality. Later, other by-products of corn may be turned into useful materials. Thus, it is expected, an enormous leak in American MILLION dollars is bet on saving the American farmer. agricultural economics will be stopped. For a decade Professor Sweeney has been devoting his knowledge and inven- tive ability to cornstalks. About 150,- 000,000 tons of them, he computes, are raised by American farmers every year; far more than any other American agri- cultural product and more than all such products put together, except hay. These cornstalks, hoed, fertilized and saved from insects, the farmer throws away. Only the fact that this has always been done keeps sane people from laugh- ing at the absurd spectacle of millions of farmers carefully raising cornstalks and doing nothing with them. More is involved than the mere future prosperity of the corn belt, for there can be little doubt that the real trouble with American agriculture, the chronic disease which is keeping the farmer so poor that continual political ‘‘relief” is demanded to prevent universal bankruptcy, has nothing to do with soil or marketing or the tariff but is merely the failure of American farmers to keep up with the applications of scientific research—some- thing that has been done by virtually every other major industry. Manufacturing industries maintain re- search laboratories costing millions of dollars every year to study processes, im- prove products, and prevent wastes. Meat packers, as the familiar phrase goes, ‘‘save everything but the squeal.” Gases from coke ovens, once thrown away, now yield chemical products which have be- come the mainstays of the business. The waste oils from refineries are turned into good gasoline; slag from blast fur- naces makes excellent brick and mineral wool; even city garbage is made into lu- 19

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Oe OE 20 bricating grease, stock food, fer- tilizer, and combustible gas. Farmers, however, still throw away every year billions of tons not only of cornstalks but of wheat straw, oat hulls, peanut shells, potato and vegetable vines, cull fruits and fruit pits, and scores of other by-products. Only in a few agricultural industries, where there has been some de- gree of centralization and unified management, like cotton growing, sugar production, and fruit can- ning, has real effort been made to see if these farm wastes, by far the vastest industrial wastes in the world, can profitably be stopped. N 1928, the average farm worker in the United States earned the equivalent of about $1,000. In the same year the average worker in manu- facturing industries earned nearly $1,700 and the av- erage store clerk or other person in mercantile pur- suits over $2,100. That is the farm story in a nutshell. The farmer earns too little for his time; less than half the average income of all persons gainfully employed in the United States. I know farmers who live in modern homes and have automobiles, electric light, gas cook stoves, radios, and the other comforts and luxuries that the city dweller enjoys. They are not ‘‘gentleman farmers,” either, but examples of the good, old-fashioned “dirt” variety. But they are rare exceptions. Until they are the rule, until every Amer- ican farmhouse equals the average city home, until the farmer can send his children to college, insure his life adequately, and find reasonable facilities for culture and social life near his home, there will be something radically wrong with American agriculture. For the way that farmers now live is not merely a symptom of the farm’s economic sickness, it is perhaps that disorder’s chief cause. If farm life is uncomfortable and unin- teresting, if it yields less money and fewer of the things that people desire than living and working in towns and cities, then most people who have brains and energy to manage it will get away from the farm as quickly as possible—which is precisely what nearly everybody has been doing for fifty years. TO GET back these lost brains, farming must provide more money. Politics is but a temporary expedient, for no gov- ernment can be expected indefinitely to support a losing industry. Fewer farms and shortage of foodstuffs might mean higher prices for a year or two, but such a situation is still less in the public inter- est and could not last. Better fertilizers, stimulating “plant pills,” ‘‘trained bac- teria” to improve the fertility of soils, increased use of farm machinery and of rural electrification, more highly diver- POPULAR SCIENCE MONTHLY Cornstalk pulp was tested in this chemical machinery by Pro- fessor Sweeney as a laboratory test tube is used by chemists. sified crops, and dozens of other expedi- ents suggested by farmers, soil experts, or politicians all are but partial remedies for the deep-seated disease of American farming. For a real cure, farming must accept the lesson taught by other industries. Farms must industrialize, adopt efficient processes, finance scientific research, save and use every possible by-product. So far, it must be confessed, agricul- ture has had more harm than benefit from industrial chemistry. Indigo, once an agricultural staple in India, is now al- together synthetic. Synthetic tanning materials have also cut into the farmer’s markets. Chemical processes of making hard edible fats from peanut oil and cot- tonseed oil have resulted in decreased prices and markets for natural lard, once the main ‘‘money crop” of the hog raiser. But synthetic chemistry has nothing against the farmer. It is merely that the farm’s competitors have been quicker to call it in. Now it must be the farmer’s turn. Cornstalks, the raw material of the new industry to be based on Professor Sweeney’s researches, contain three chief materials. Most of the fresh stalk is wat- er, easily removed by drying. The solid matter which is left contains about one APRIL, 1930 N ut and orange growers have found the secret of big cash returns: codperation and no waste. third of its weight as a gummy chemical material called lignin, also present in most kinds of wood. About another thirc is composed of pentosans, which resemble the sticky substances in ordinary mucilage and remotely resemble starch. These pen- tosans are not useful for human food, but can be utilized by several kinds of bac- teria with the production, it is expected, of a number of useful chemicals. The other third of the weight of the average cornstalk is ordinary cellulose; the white, fibrous material of cotton or of the wood fiber used to make paper. Paper can be made, indeed, from the cellulose fiber of cornstalks, as can many other cellulose products ranging from smokeless powder to rayon. It is pro- posed, however, that the first main prod- uct of the new cornstalk industry be a kind of synthetic building material of the wall board class, made by compressing the cellulose fiber and much of the lignin of the stalks into hard, woodlike sheets. NOTHER material, made in Profes- sor Sweeney’s laboratory and recent- ly tested by the United States Bureau of Standards under the name of ‘‘maizo- lith”’ or ‘‘maize stone,” is said to consist of the cellulose fiber of the stalks treated chemically so that the fibrous structure degenerates into a featureless jelly. This jelly is then compressed and hardened into a substance resembling hard rubber and which, it is believed, may be useful for electric insulation, for the making of noiseless gears, and for similar purposes. From one hundred pounds of natural cornstalks it is possible to produce, Pro- fessor Sweeney finds, twenty-four pounds of the liquid called furfural, now finding increasing uses in chemical industries as a solvent and selling for eight or nine cents a pound. Two of Professor Sweeney’s associates at Iowa State College, Dr. Henry Gilman and A. P. Hewlett, have been able, by further chemical manipu- lation of the cornstalk materials, to make a new sweetening material said to be 300 a a a ee a ee a ee a ens ati. tate to

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f t 1 “ 5 1 r l f veiw ee vs we & 0 sv 9° AprIL, 1930 On this Canadian farm straw is still burned because it has always been burned that way. times as sweet as sugar and possibly use- ful for persons unable to eat sugar, as coal-tar chemicals, like saccharine, are used now. More than three thousand separate chemical materials can be pro- duced, Professor Sweeney states, from the three fundamental raw materials lignin, pentosan, and cellulose present in the country’s enormous waste of cornstalks. But there are many agricultural wastes in the United States almost equal in amount to the corn- stalk harvest and probably with equal possibilities. The chief of them is probably straw, including the dried stalks of wheat, oats, and other grains and containing fundamental chemicals similar to those in cornstalks. The same cellulose fiber is present, and paper or similar materials have been made from straw as rice paper has been made for generations in China and Japan. Oat hulls, chemically similar to oat straw, already have been put to use in making furfural by a bacterial process similar to the one pos- sible on cornstalks and also on the other corn farmer’s waste of dried cobs. Buck- wheat hulls constitute another waste of the same kind, now unused. Still others are the pea vines, bean plants, dried pods, and similar wastes of these kinds of farming. From all such strawlike materials well- known chemical processes can yield a rare sugar called xylose or ‘‘wood sugar.” hitherto a chemical curiosity but with properties, the Bureau of Standards says, ‘‘which ought to make it a desirable ma- terial for use in the food, textile, and leather industries.”” The Alabama Poly- POPULAR SCIENCE MONTHLY These boards, nearly half an inch thick and capable of being sawed and nailed like wood lumber, are made of the despised cornstalks. technic Institute is engaged on commer- cial-scale researches in the manufacture of xylose from peanut shells and the oil- less residue of cotton seeds. From straw of almost any kind chem- ical processes can prepare, it is reported, not only furfural and xylose but acetic acid like that present in vinegar, methan- ol or ‘‘wood alcohol,’ oxalic acid used in cleaning stoneware and plumbing, tar, illuminating gas, woodlike materials re- sembling those made from cornstalks, paper, and several kinds of wall board materials useful for absorbing either sound or heat. 21 Among more specialized agricultural industries which already have utilized by-products successfully, an example is the pineapple industry of the Hawaiian Islands. When slices of fresh pineapple are prepared for canning much of the fruit must be pared away to remove the hard, scaly rind. The parings, although containing a great deal of good pineapple substance, formerly were thrown away as useless. Some years ago a group of chemists and engineers headed by one of America’s foremost food experts, Charles F. Ash of San Francisco, developed chemical pro- cesses for saving this waste pineapple. From it the industry now recovers vast quantities of pineapple syrup, sugar, citric acid, and other salable substances, materially increasing the income of the industry. If more by-product sugar and syrup are produced than can be used or sold, the excess is fermented with yeast and distilled to yield industrial alcohol. The sugar industry is another that is saving-its by-products. Waste molasses is fermented to yield alcohol. Fiber from Professor Sweeney used this cornstalk harvester in his experiments to show that this vast by-product is valuable. the waste sugar cane is made into wall board, heat-insulating material, sound insulators, and so on, until these former by- products are said now to be more important in some regions than the sugar itself. The cotton industry now makes use of its by-product cot- ton seed; oil and a compressed cake useful for stock food or fer- tilizer being the chief salable materials. Recently the short cotton fibers or ‘‘lint- ers,” which adhere to the seed when cot- ton is ginned, have found use as one of the raw materials for rayon. The dairy industry now uses the casein, once thrown away in skim milk, to make plastic ma- terials resembling hard rubber. The tobacco industry uses waste stalks and coarser leaves as a source of nicotine, turned back to agriculture as an insect- icide. In the food canning and preserving in- dustries the hard seeds of peaches, apri- cots, and sim- (Continued on page 159) Ge PARENT TIA tte ei Te ee ee ee . 4 pees Goes oa = % fp

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POPULAR SCIENCE MONTHLY AprIL, 1930 Modern Hotel is a Huge Machine A Glimpse at the Mechanical Servants That Perform Superhuman Tasks Hidden from the Sight of Guests By ALDEN P. York’s forty-three storied hotel— the highest in the world above the street and the deepest below—is pre- paring to open its doors to the public at midnight. An army of workmen com- plete last minute jobs, engineers and managers hurry through the corridors. A flash and a sputter. Trouble on the sixth floor. A whole panel of electric fuses has blown out. Half the building is plunged in darkness. And only six hours before the opening. Telephones jangle in the chief engi- neer’s office. Every electrician in the house is up to fix the break. Cables have burned off and dropped out of sight down conduits. ‘“Can’t be fixed in less than three days,” is the verdict. But this is a time when the impossible must be done. Ten o’clock, and they are fishing for the cables by the light of flashlights. Eleven o’clock, and the first guests are arriving. No time to trace connections. “Splice them on to any power line!” comes the order. Twelve o’clock the entrance doors swing open. The hotel is flooded with light. It took three days’ work to straight- en out the connections later—but on its opening, the New Yorker Hotel was lit. Its chief engineer, Warren D. Lewis, faced me over a desk in his subterranean office. I saw a keen, alert face, a firm chin. Brown hair, tinged with gray. Blue eyes, a little tired, it seemed, behind thin gold-rimmed glasses. His job was to get the hotel’s machinery going, and keep it going. The New Yorker Hotel, probably the most-mechanized hotel in the world, is a “vertical village” that can hold 5,000 inhabitants. It has 2,500 guest rooms— only the Stevens Hotel in Chicago, with St o’clock in the evening. New

tid, Me d) i) BELTS MOVE IN DIRECTION OF ARROWS, CARRYING DISHES }/ é - mae it!

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RSTOMATIC 2, IDLER KEEPS DISHWASHER CLEANS ~ ~ BELT TAUT 12,000 PIECESOF ~~ -_ CHINA AN HOUR ~~ This ingenious device carries used dishes on overhead moving platforms toa machine that washes 12,000 pieces of china an hour. ~~ NOVEL BELT SYSTEM CONVEYS DISHES TO WASHER 3,000, has a greater capacity. Erected so recently, the hotel was able to take ad- vantage of the last word in mechanical equipment—competent, superhuman serv- ants unseen by the guests. They are buried, mostly, in four underground floors, like the machinery behind the scenes of a modern theater. I had already passed through an im- pressive lobby and descended winding staircases, so many that I lost count, to

Warren D. Lewis, chief engineer, in the power room of the hotel’s independent lighting plant. reach the office of the chief engineer in the fourth basement, seventy-eight feet underground. Through its windows, “I saw what looked like the engine room of a great steamship. “Tl take you through the hotel,” Lewis said. “We'll start from the bot- tom up.” Black cylinders with gleaming metal bands— those were the four steam engines in the hotel power plant, with flywheels tall as a man. They were coupled to dynamos. The hotel makes its own elec- tricity for everything from lighting lamps in the guest rooms to cleaning carpets. More economical, they find, in the long run. INDICATOR’ SHOW POSITION OF ELEVA p<. BY COLORED_LIGHTS

ELEVATORS FROM L OBBY ~

TELEPHONE PERMITS , DISPATCHER TO SPEAK WITH ANY OPERATOR Express elevators in the New Yorker rise 700 feet a minute and automatically stop at signal. What if the steam engines should fail, with no outside electric connection? A Diesel engine as big as a street car is ready for an emergency. Resembling a giant automobile motor, it has eight cylin- ders, and burns oil. It is the only com- pletely independent power plant of its kind in the world. The Diesel was the hardest single piece of machinery to get into the building, the chief engineer said. It was lowered from the sidewalk out- side, after a huge truck had brought it, by a portable derrick. A hole had been left in the wall to get it in. The whole power plant, Lewis said, could supply a city of 35,000. “We built it plenty large enough,” he said, “‘so that later we might use some of the power for other buildings on this block.” Exhaust steam from the engines is utilized to heat the hotel. The steam comes from four towering boilers, each as large as a banquet hall. “4 man in evening clothes could fire them without getting a smudge,” Lewis said. The firing is done by pressing buttons. One starts a blower and shoots a blast of pulverized coal into the boilers. Another blows the ash—a half gallon to a ton of coal—by compressed air into a truck waiting outside. No dust, no men with shovels. Running the boiler in one of the world’s biggest hotels is simpler than in the average home. We climbed a circular staircase and zigzagged through corridors. The place is immense. “Many employees got lost,” Lewis said, “‘just before the hotel opened. They would be sent out on a half-hour job and the boss wouldn’t see them until next day.” “Stand back!” A traveling crane whizzed by on an overhead monorail track. From it dangled a sievelike metal drum, a “laundry basket,” holding several tons. We were in the largest electric laundry in the world. It had its first real test the day before the hotel opened. An enormous consignment of linen, 40,000 pieces, arrived in one batch

Tow Vici Stat;

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ApRIL, 1930 tea x 5.000 go Towering high above the throngs in the Vicinity of the Pennsylvania Railroad’s Station, the New Yorker, with its 7,000 windows, is an impressive sight at night. POPULAR SCIENCE MONTHLY at eleven in the morning— mostly sheets and pillow cases. All had to be laun- dered before they were used. Between one and two in the afternoon, the last piece was on its way up an “esca- lator” or moving runway that takes it to the linen room. In a working day the laundry can handle 130,000 pounds of linen—a little more than its daily require- ments. Bed and table linen make a hotel’s wash enor- mous. The New Yorker’s 52,000 sheets alone would cover thirty acres of ground. Through an open door we saw busy chefs cooking on the kitchen’s thirty-eight sectional gas ranges. In the bake shop was an automatic weigher, measuring out in- 23 gredients from a hopper behind two elec- tric ovens. We ducked beneath an over- head chute of gleaming copper. Trays of dishes glided along it, propelled by some unseen force, on their way to the dishwashing room. They switch around corners through an ingenious system of moving belts and enter the dishwasher— a metal contrivance eight feet long that handles 12,000 pieces of china an hour. “Diners don’t know what work goes on behind the scenes so that they may eat,” Lewis said. “There’s even more to it than this. A couple of unsung heroes worked fifty hours without sleep, not long ago, printing menus in the print shop”’. Emerging from the basements, we paused in the lobby. In a space surround- ed by elevators marked “Local” and “Express,” an employee manipulated but- tons on a control stand. He dispatches the elevators as a train dispatcher controls railway trains. Forty-three stories of “ver- tical traffic,” as (Continued on page 141) s io in every room gives a choice of four programs. aaa ei as onauaaninderebalgdeedadenediaonmabbgenaatanat

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ns ee ee SAE Pee ‘ cic Letes eekees ee ee The ‘call of the crane” greets a pilot at Ross- itten, Germany, as he passes tests for a license. N SIXTY-FOOT wings, a human gull, W. Hawley Bowlus of San Diego, Calif., the other day soared over the California sea coast for more than six hours. His long ride on the air currents set an American endurance record for motorless planes. Bowlus, who built his own ship, is the ace of American glider pilots. Four times in recent months he has advanced the en- durance mark until it now stands more than two hours beyond the four-hour-five- minute mark made in a German sailplane on Cape Cod, Mass., by Peter Hesselbach in 1928. In his honor, the San Diego en- thusiasts have named their organization the Bowlus Glider Club. Shortly after the new record was set, Col. Charles A. Lindbergh and Mrs. Lind- bergh both won first-class glider pilot’s licenses by soaring more than five minutes near San Diego in Bowlus sailplanes. Lindbergh’s license is number nine; Mrs. Lindbergh’s number ten. The first man to obtain ‘a first-class license in America was Lieut. R. S. Barnaby, of the Navy, who recently cut loose from the Los Angeles at Lakehurst, N. J., and {spiraled down 3,000 feet in a glider to a safe landing. Within a few weeks, Captain Frank M. Hawks an- nounces, he will begin a double transcon- tinental glider flight. His machine will be towed behind an airplane, starting and ending the flight at New York City. At every important city along the route from Los Angeles to New York, Hawks plans to cut loose from the plane and glide down to demonstrate the ease of motorless flying. Although gliders towed by airplanes have made short flights in this country, no flight of this length has ever been made in the history of gliding. It will be a new record for Captain Hawks, who already holds the speed records for nonstop flights in each direction between the Atlantic and Pacific in an airplane. He plans to arrive in New York at the end of his trip in time to participate in a two-day carnival of motorless flying at Bayside, New York. POPULAR SCIENCE MONTHLY 3 os os * 5 ee APRIL, 1930 et into Gliding Why the thrilling sport of motorless flying is sweep- ing the country and how you can get started in this great game. The equipment you need and what it costs; how to go about organizing a club. By EDWIN W. TEALE ing incident. When the first article p. 19) was prepared, a few weeks Py % of this series (P.S.M., Mar. 30, Colonel Lindbergh, right, gets his glider license and W. Hawley Bowlus congratulates him. Meanwhile Edward S. Evans, honorary president of the National Glider Associa- tion, is offering a prize of $3,000 to the first American to make a motorless flight of twenty hours over American soil. A sidelight upon the recent rapid growth of the glider movement in America is contained in the follow- ago, the official endurance record was one hour and twenty-one min- utes. (Hesselbach’s four-hour flight was not official.) When the first proofs of the story returned from the printer, this figure had advanced to two hours and forty-seven minutes, and when the magazine went to press, it had leaped to five hours and twenty-seven minutes. The number of clubs affiliated with the National Glider Association, when the article was written, was twenty- five. When the first proofs came back it was thirty, and when the magazine ap- peared on the news stands it was thirty- two. During coming months, many addi- tional groups plan to purchase gliders This is the way a glider is launched. Several men hold the rudder cord, while others are tugging at the shock cord in front. At the pilot’s command these men let go the rope and away shoots the plane. mre ye:

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a Se ee aE writ” ed e Aprit, 1930 and to take up the thrilling pastime of coasting on the air currents. For gliding is a “social sport.” That is, it has to be practiced by a group working together. One person cannot buy a glider and fly it himself as he operates a bicycle or an automobile. To launch the machine from hillsides requires the help of several people. This is why clubs, sharing labor and expense, make the greatest progress. In Germany more than 200 such clubs are in active existence. Where can I get a glider? What will it cost? How shall I go about organizing a club? What kind of country is needed for gliding? These are the questions most fre- quently asked by those who want to get into the gliding game. As to the first question: The National Glider Association has made a survey of the manufacturers of motorless planes in all parts of the country. [HE products of a ‘dozen of these com- panies, located in Michigan, Ohio, Kansas, New York, Massachusetts, Cali- fornia, Oregon, and Washington, are en- dorsed by the Association. This list of manufacturers is on file at the offices of POPULAR SCIENCE MONTHLY and will be sent to any reader upon request. One manufacturer plans to build a thousand gliders this year. These training planes will be constructed with interchangeable parts so repairs and replacements can be made easily. Complete parts, ready to assemble into finished gliders, will also be sold by some companies. The cost of a practice glider varies. The average is about $400. Delicate soaring planes often run in excess of $1,000. An increased demand and mass production undoubtedly will result in a ” At left: Pilot is strapped in the glider’s seat, ready for the take- off. Above: Illustration shows the right way to hold on to the “4 shock cord while stretching it to launch the plane for flight. POPULAR SCIENCE MONTHLY Up in the air at Roosevelt Field, New York where Heinrich Knott, Chief Instructor of the American Motorless Aviation Corp., shows students how to launch a glider. reduction of these prices. When glider parts are purchased and assembled by club members, the materials cost about $150. Expert workmanship is required to build a safe and successful motorless plane, and it should be attempted only under the supervision of a licensed me- chanic, pilot, or airplane builder. The shock cord, a rubber cable about seven eighths of an inch thick, which is attached to the nose of the glider and stretched out by running men to launch the ma- chine from hillsides, costs between twenty- five and forty dollars. A CABLE of good grade should be secured, as an inferior one may dete- riorate and break under strain. A broken shock cord has the kick of a mule and may seriously injure the pilot sitting in the glider for the take-off. When a glider is purchased, a store of repair parts should be obtained also to save delays later in taking care of small accidents. Many gliders make from 500 to 800 flights without even break- ing a wire. One machine, at the University of Michigan, has a rec- ord of 6,000 flights. Though it has been frequently patched and repaired, this veteran ‘“puddle- 25 jumper” is still in active service. A unique practice room has been added to the equipment of one club in Massachusetts. Propellers blow air toward a stationary glider from different sides, giving the operator practice in maintaining balance -without leaving the ground. Other clubs have anemometers mounted at practice fields to determine the velocity of the wind. For practical purposes, however, a bunch of dry hay will tell a glider pilot all he needs to know about wind ve- locity. The rule is: if a handful of hay dropped from a height of five feet is carried more than ten or twelve feet before hitting the ground, the wind is too strong for practice hops: A Glider Pilot’s Logbook, for keeping individual records of flights made, may be obtained free from the headquarters of the National Glider Association, Detroit, Michigan. T PROVIDES for entries such as: Date, Hour, Location, Type of Ter- rain (that is, the height of the take-off hill and the character of the surrounding country), Wind Velocity, Wind Direc- tion, Type of Glider Flown, Method of Launching, Duration, Distance, Altitude, Remarks on Unusual Features of Flight. A club which is a member of the Associa- tion may obtain. official recognition for records set by its members and for the qualifying flights for pilot’s licenses which they make. A contest committee, ap- proved by the N. G. A., does the official timing. A thirty-second hop straight down a hillside qualifies a flyer for a third-class license. A one-minute hop, with a complete right, left, or “S” turn, is required for a second-class license; and a five-minute soaring flight above the start- ing point for a first-class license. At German gliding schools, when a student passes the time necessary to win his license, all the spectators give the curious glider salute, “the call of the crane.” They stand on their right legs, stretch forth their left hands and imitate the bird’s note. This same salute is accorded pilots who land with new records. When a club has twenty or more members, the initial ex- pense to each is slightly more than twenty-five dollars. Fre- quently local organizations aid groups to get started in gliding. When six or seven University of Michigan students, a few years ago, decided to form a motorless flying club, they had little money. They presented their plan to the Exchange Club of Detroit, which raised $600 and bought their first glider for them. The organiza- tion has now grown until it has (Continued on page 152) 7 2 AT hy A te Dig ODE tn a 5 lt 7 = 4

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Aprit, 1930 POPULAR SCIENCE MONTHLY 27 Explore Weird Island of the Dead Scientists plan to invade mysterious Easter Island in an effort to solve the secret of its stone images, carved centuries ago by a forgotten race. Who were the strange men who lived on this most isolated spot? O FIND the answer to a riddle that has baffled science for two hundred years, a group of twenty scientists from the Univer- sity of Pennsylvania will go next spring to Easter Island, a mysteri- ous pin point of land in the mid- dle of the South Pacific. Though populated by a handful of natives, it is primarily an island of the dead. In a nearly unbroken line, a series of monumental burial platforms stretches around its rugged coast, a gigantic stone memorial wreath to the forgotten great of a forgotten race. Nobody knows what hind of people built them nor when they were constructed. More than 2,000 miles off the Chilean coast, its nearest island neighbor 1,000 miles to the west, Easter Island—a tri- angular fragment of volcanic land only forty-five square miles in area—is the most isolated inhabited spot on earth and one of the least accessible. So remote does it stand from estab- lished traffic routes that, when a Spanish ship failed to locate it following an earth- quake in that region in 1922, it took months to correct the captain’s report that the island had disappeared. Only a few explorers have visited the place. And what they discovered there constitutes one of the world’s most interesting un- solved mysteries. The enormous tombs, about 260 in all, some of them 300 feet long, fifteen feet high, and topped by terraces that in some cases measure 100 feet in width, are not the only startling feature of this mid- ocean graveyard of antiquity. Face down, like huge ninepins, more than 600 colossal stone busts lie scattered on the island. No one has discovered who carved them out of the volcanic rock—or why. T= grotesque, solemn-visaged statues, the largest of which range from thirty to seventy feet in height and weigh from forty to 250 tons, were not always in their present position. There is every indica- tion that many of them were used to ornament the burial structures, which are provided with large oval stone slabs for their support. A century and a half ago, one of the earliest seafaring men to view More than 600 of these huge images in stone have been found on the slope of Rano Raraku, and other parts of Easter Island. Who made them, when, and why is a mystery to scientists. By MICHEL MOK this strange marine mausoleum in a log entry expressed amazement at finding ‘‘the seashore lined with numbers of stone idols with their backs turned to the sea.” Why the images are no longer standing is pretty well known, but that is just about the only phase of the Easter Island mystery that has been solved so far. How old are these monstrous figures? Their age has been estimated at from 2,000 to 5,000 years. Possibly, it may have been much longer. Were they idols, as the eighteenth century navigator thought, or the crude stone portraits of then-living chiefs or their illustrious an- cestors? There are no satisfactory answers to these questions. fee images were quarried inside the large crater of Rano Raraku, one of the island’s three extinct volcanoes, whose ledges and slopes still are studded with scores of them, some completed, but many more in various stages of creation. How did their makers, doubtless ignorant of all but the simplest mechanical con- trivances, manage to lower the immense statues from the crater’s upper terraces to the bottom and then over the wall to the plain below? Above all—what halted this vast

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Sn . ee See on ak. on anne 28 This is a model of the $1,500,000 yacht which will carry scientists to tiny Easter Island next spring. It will be equipped with a laboratory and also carry seaplanes. —- = a = i UAM oT U ARCHI PELASO Stranded in the midst of the Pacific, Easter Island is the world’s most iso- lated inhabited spot. It lies 2,000 miles from Chile -——- -— —- POPULAR SCIENCE MONTHLY —— -oaeereoeo-| -_-- EASTER “ISLAND -—— Sm em ae ae we ee |"GALAPAGOs ARCHIPELAGO -_— a -_— _ — 500 1000 a ee es) SCALE OF MILES i and 1,000 miles from nearest land. undertaking? Rude stone implements have been found and to this day are lying on the mountain slopes and in the quarry, apparently just as the workmen left them centuries ago. This, and the fact that a majority of the images remaining in the quarry are unfinished, seem to show that labor was stopped by some sudden devastating force. was it war, pestilence, famine? Or did a great catastrophe of nature blot out the busy scene and wipe out the workers? Again, nobody knows, though guesses are not lacking. Earthquakes and vol- canic eruptions have been advanced as probable solutions of the mystery, but there is little geological evidence to sup- port them. Moreover, had such upheavals taken place, probably the figures. and burial platforms would have been shat- tered or covered with lava. The most romantic of the theories sug- gests that Easter Island, ages ago, may have been the highest ground, as well as the cultural and religious center, of a much larger island or perhaps even a vast continent, since sub- J. Thoulet, veteran French oceanographer, who studied the currents and bottom con- ditions of that part of the Pacific in 1928. Though this is mere theory, translations of hieroglyphic inscriptions on ancient wooden tablets found on the island indicate that, at any rate, drastic climatic changes may have occurred there when the world was young. To wrest the secrets from this prehistoric ocean mor- PHI OT PIMPS HALUR SEAMASTER Courtesy of American Museum of Natural History One of the seven ancient wooden tablets inscribed with hieroglyphics, found on mysterious Easter Island. Only two of them as yet have been translated. "mo tuary, the University of Pennsylvania expedition will be elaborately equipped. It will set sail for the South Pacific as soon as a $1,500,000 motor yacht, de- signed especially for the purpose, is com- pleted, probably in May, 1931. The 265- foot boat, the Caroline, one of the largest private Diesel powered vessels ever built in this country, is the property of Eldridge R. Johnson, a trustee of the University and former president of the Victor Talk- ing Machine Company, who will sponsor the expedition and accompany the party to Easter Island. Powered by two 1,500-horsepower engines operating twin screws, the Caroline will have a complete laboratory on her upper deck. She will carry deep- sea dredges as well as seaplanes in which to make reconnaissance over uncharted seas. One of the age-old problems presented by Easter Island which the expedition, with its wealth of modern exploration paraphernalia, may be able to solve is [WClOCTEDU:LA LH ISRENAE Smee 133M ENT BEA LEELE RIN the one of the origin of its inhabitants. Where did these people come from and how did they reach this remote spot? Did - they migrate from Chile or Peru, in South America, more than 2,000 miles to the east, or did they sail against the prevail- ing winds from the “nearest” islands of the Tuamotu Archipelago, about 1,000 miles to the west? Legends of the Maoris record that they stopped at Easter Island on the way from Peru to New Zealand and erected the stat- ues and burial memorials in conformity with a custom on arriving in a new land. This, too, would account for the unfin- ished condition of some of the images. No similar works, however, have been found in any known Maori settlement. NLY some 200 Kanakas are now living on the island. They know little about the marvelous mausoleum that is their homeland, and care less. Were the men who wrought the wonder- ful works the ancestors of the present inhabitants? Were they the Maoris or did they belong to a much earlier, vanished race? In any event, the Easter Is- landers of today have not in- herited their culture. They live in Mataveri, the only village, near Cooks Bay on the southwestern coast, and tend the herds of sheep and cattle of a Chilean com- pany that exploits the island asaranch. The company’s manager is the only white MALT man in the place. A vessel with mail and supplies puts in about once a year. With the exception of this small settlement, the island is virtually one big cemetery. Aside from the tombs, there are thousands of graves; (Continued on page 157)

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30 — FOP oe ete —- i = a eae - Se eon SS, er we ww * Aprit, 1930 POPULAR SCIENCE MONTHLY 29 NEW IDEAS AND INVENTIONS On this and succeeding pages are described the latest achieve- ments of inventors and novel applications of scientific progress Front view of the locomotive. Note how the stack is sunk in a depression along the top. NEW BRITISH LOCOMOTIVE A STREAMLINED GIANT LIKE a mammoth armadillo on wheels is the new British steam locomotive built for express passenger service on the London and Northeastern Railway, which can now boast the longest and heaviest locomotive in Great Britain. The novel “streamline” giant owes its peculiar appearance to the facts that the wide boiler overhangs the locomotive’s drive- wheels on each side, and that the smoke- stack does not project above the boiler. The stack is sunk at the front of a central depression along the top of the boiler. This arrangement is said to throw the smoke clear of the driver’s view. The streamline design was developed by test- ing a model in a wind tunnel, in air speeds up to fifty miles an hour. Unusual features distinguish the en- gine from its predecessors. It has an unusually high boiler pressure of 450 pounds per square inch, the ordinary pressure for British locomotives hitherto being 200 to 250 pounds. The object of the high pressure is fuel economy. An- other feature is that the entire air supply to the fire grate is preheated. Mechanics working at the Darlington shops where the locomotive was con- England’s newest and largest express locomotive, showing streamline design and overhanging boiler. because of the extreme secrecy attending its birth. After preliminary trials, it will soon be tested out on the London-to- Edinburgh service. LOWER OBSERVATION CAR FROM ARMY DIRIGIBLE A DIMINUTIVE car carrying an observer swung hundreds of feet below a flying airship above Langley Field, Va., in a recent Army Air Corps test of a newly- applied device for seeing through the clouds. It was believed to be the first successful try-out in America of this method, first applied in German dirigibles: on bombing raids, of directing an air- ship’s flight while the airship itself flew above the clouds, out of the sight of per- sons on the ground. The car used in the Army test is a small cabin hung by a cable from the dirigible. Like the German models, it is lowered and reeled in while the craft is in flight. ‘The observer in the car directs the ship’s maneuvers by telephone, made possible by a core of telephone wire in the supporting cable. For emergency a mechanical signaling device is provided. Use for the device, Army officers say, may include not only directing bombing operations, but also making close-up photographs of enemy positions while the dirigible flies unseen. For peace-time use, it may assist dirigibles landing in fog. The device was developed by the Mate- riel Division of the Army Air Corps at Wright Field, Dayton, O. “BOMB” DROPS FREIGHT FROM AIRPLANE WHEN the precision clockwork within a new bomblike container is set, it may be dropped from a plane flying at heights up to 6,000 feet and a parachute will open and lower it gently to earth. The device, a Swiss invention, is intended to facilitate structed called it the “hush hush” engine This rear view shows the interior of the en- gineer’s cab, with controls and instruments. the delivery of goods by air freight. It comprises a cylinder of aluminum, in which the materials to be delivered are placed, and an attached container which releases the parachute. The clockwork to open the.parachute is set according to the altimeter. A special dropping gear provides for the release of five of the cylinders from a single plane. NEW LENS INVENTED FOR PANORAMIC MOVIES THE same laws of optics that make a tall man into a squat pygmy when he observes his reflection in an amusement park mirror are put to work in a new French lens for motion picture cameras. It simplifies the making of films for the newly-popular movie screens of double width, since it permits the use of stand- ard movie film instead of the double- width film used in America. The result is economy in film and in the amount of special apparatus required. More cylindrical than circular in form, the new lens squeezes twice the usual width of view into a standard-sized pic- ture, although vertical dimensions are undistorted. When the film is projected

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30 a similar lens is used to throw it on the screen. The projector lens thus “un- distorts” the picture and the result is a clear photograph of normal height and of twice-normal width. Other possible applications seen for the novel lens are in making talking movies, where the lens would save film by allowing the part carrying the sound record to encroach on the space usually occupied by the picture; and in color movies, where it would compress the triple number of pictures required into a normal length of film, with advantages in economy and in avoiding “color fringes” around rapidly moving objects. TOOL COMBINES SQUARE, GAGE, PLUMB, LEVEL A COMBINATION tool of extraordinary compactness and many uses has been devised for carpenters and home wood- workers. Used in conjunction with an ordinary carpenter’s two-foot rule, it is convertible into a right- and a left-hand bevel square, a compass, and a try-square. It also serves as a plumb and a level, or an inside square and a depth gage. The device is a small frame of aluminum in the shape of a right angle triangle and provided with a clamp that grips the folded carpenter’s rule in a position at right angles to one of the sides of the triangle, and at an angle of forty-five degrees to each of the other two sides. Thus it serves either as a try-square or The triangular tool, used with a carpenter’s two-foot rule, serves as a handy bevel square. a bevel square, according to the side which is placed against the work. Since, in the try-square position, the rule can be adjusted to extend any distance within its limits from the edge of the tool, it can be employed as a depth gage and a marking gage. The device holds a small bubble level which is exposed when the rule is re- moved. Without the rule, also, it serves as a small square for corners which can- not be reached with an ordinary try- square. NEW CORE FOR CASTINGS Founpry practice may be made over by a new core for castings made of sand and surrounded by a rubber compound. Under the pressure of the solidifying metal, it eventually collapses, and the residue is poured out. Formerly it had to be chipped out. POPULAR SCIENCE MONTHLY HANDY PRESSURE GAGE FITS IN TIRE RIM A NEw substitute for the ordinary tire gage carried by motorists is an air pres- sure gage which fits into the rim of the wheel. Resembling a tire valve, a red dot in its center moves up and down to tell at any:time the approximate pressure within the tire. The little red dot is on the top of a rod which rises and falls within the gage. When the dot is flush with the top of the gage, the tire pressure is exactly right. The new gage is inserted through the rim only, and does not enter the tire it- self, but simply reacts to the pressure. To install it, the air is released from the tire, the tire and tube are pushed to one side, and a 34-inch hole is drilled through the rim. STEEL BALLS NOW USED TO CARRY HELIUM Srx steel balls mounted on a flat car constitute a novel helium container, recently developed for transporting the airship gas from Texas fields. Formerly elongated cylinders carried on flat cars were used for this purpose. Because their shape permits twice the usual pressure to be applied to their con- tents, the spherical containers can carry twice as much gas as cylinders of the same volume. Ina recent test one of the six-foot spheres, made of inch-and-a-half-thick steel, was filled with helium at a pressure of 1,250 pounds to the square inch, and run off a twenty-five-foot bank. It was unharmed. Later it exploded only when the pressure was raised as high as 4,500 pounds. HARDEN STEEL BY NEW MAGNETIC PROCESS MAGNETISM can be used instead of heat to super-harden metals, according to the recent discovery of E. G. Herbert, British metallurgist. Test specimens of steel which he hardened by subjecting them to magnetic fields of repeatedly changed polarity could not have been hardened more by special heat treat- ment, he reported to the Iron and Steel Institute. Whether the new way of hardening is of commercial value has not yet been determined. Evidently both heating and magnetic treatment subject the atoms APRIL, 1930 of metal to the same action that results in the hardening process. Thediscovery may lead to new and important knowledge about the structure of magnetic metals, such as iron and steel. NUMBERED KEYBOARD AN AID TO BANJOISTS NO LONGER need aspirants to the art of banjo and guitar playing screw up their fingers to impossible contortions in order to strum melodies from the twanging strings. A new type of stringed instru- ment demands merely a knowledge of an index numbered from one to twenty-one for its production of chords. A small compact keyboard made of Swedish spring steel fits over the neck of the instrument, containing a system of levers which press down on the ‘strings according to the various chord patterns. There isa numbered key on the keyboard corresponding to each chord pattern. There are twenty-one keys altogether, all of them within easy reach of the fingers. If one wishes to play “Old Man River,” for instance, he finds what numbers on his banjo keyboard cor- respond to the chords on the printed music, and then writes those numbers over each respective measure of the music. All he has to do then in order to play the piece. is to press the keys of the corre- sponding numbers. Pressing one of the numbered keys (shown — under glass) automatically “fingers” a chord.

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POPULAR SCIENCE MONTHLY rip i. { 7a Sanitary Garbage Truck. To remove garbage and ashes without causing odor or dust in the streets, the city of Berlin, Germany, has introduced this special truck. Refuse cans are emptied into swinging receptacles at the front of the body. A hydraulic piston swings the body to a vertical position as shown, dumping the contents into it. New Switch Controls High Voltages This compact new type of high voltage switch, en- cased in a vacuum chamber of glass, has been developed by Dr. R. A. Millikan and Prof. R. W. Sorenson of the California Institute of Technology to control the millions of volts used in laboratory electrical tests. Eventually it may be adapted commercially to replace bulky power switches. Front-Wheel-Drive Truck The front-wheel drive has been applied to the heavy motor truck in Germany. As pictured at the right, the engine is placed on a frame projecting far ahead of the front axle. The advantages claimed are economy of power in transmission and easy riding qualities. New Aids for the Deafened The top photo shows a new “‘ voice picture” apparatus demonstrated before the Cali- fornia Association for the Teachers of Deafened Adults. A light beam projects a “picture” of the deafened person’s voice vibrations on a rotating screen, helping the subject learn how to control his or her intonations. In aircle: Headphones plugged into the front pew enable the hard of hear- ing to listen to the sermon in a church at Berlin, Germany. The preacher’s voice is amplified through a special microphone. NEW IDEAS AND INVENTIONS NS A a ee Ae Chee a OT METS NANED et AO ES a — (FR Se er wma BE FR TE ST TTR TEE ne EERE ee RUN REO Te : y 2 “ : “ 555 foe? Z xg " Z —- nwo Seuerree 2 22 ssret en Sonate veietiasl a0 EO COREL RET tic ee rina 6 i in accented ies eee str rence np ale a cen Ce aN ew a pe Rete a as een Delt rate 2 Tahar gr re re Sern at ;

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ee 32 RADIO BEACONS Ce ee eh ee Transmitting apparatus that sends the radio beams from the airport. “Rapro roads,” leading avia- tors through darkness and fog from airport to airport, will be part of the equipment of every skyway in a few years, accord- ing to William Loth, a French in- ventor, who recently announced to the French Academy of Sci- ences the perfection, after several years’ work, of a novel type of radio beacon. The beacon, similar in purpose to the ones successfully tried in America, sends out a constant radio signal in a straight line. Two of the devices are used at the same time, sending their signals out so that their beams form an angle with the vertex at the airport and the opposite end in the direction of the incoming plane. On the plane, a receiving instrument picks up the signals. The pilot, listening through ordinary headphones, hears the code letter T, a dash, as long as he keeps within the angle made by the two wave lines. This means he is headed on his correct course. If he swings to the left, he hears a warning signal, the repetition of the letter N, a dash and a dot. If he swings to the right, the signal is the letter A, a dot and a dash. By observing the signals closely, the inventor says, an airman need not diverge more than a few feet from the exact course. Loth is best known as the inventor of an underwater cable used to radiate impulses which can be picked up on board a vessel, thus leading it through narrow channels and into harbors. A NEW COKE DUST FUEL THE lessened chance of spontaneous combustion, an ever-present dread in con- nection with coal yards and even domes- tic coal bins, is one of the advantages of FOR AIRPORTS At right: One of the two towers from which the signals are sent. Below is the portable receiving ap- paratus which, placed in a plane, enables a pilot to follow the radio beam signals and so keep to his course. The photo shows the appa- ratus trundled on a small cart during a recent demonstration. POPULAR SCIENCE MONTHLY a new “low temperature” coke dust for domestic and factory use. The Pitts- burgh experiment station of the Bureau of Mines of the United States Department of Commerce has found that the distilla- tion of coal at low temperatures gives, besides a more valuable yield of oils and tars than is obtained by traditional methods of distillation, a type of coke which ignites more readily than the best grades of ordinary coke. Burnedin the furnace as a coke dust, it is said to be smokeless. But in spite of its high igniting qualities, the dust can be stored away in bins with greater safety than ordinary coal, the Bureau states in its report. MAKES “ARTIFICIAL AIR” FOR PLANES AND SUBS New kinds of air, apparently as good or possibly even better to breathe than the sort provided by Nature, are the recent ‘discovery of Dr. J. Willard Hershey, chemist of McPherson College, Kansas. Artificial mixtures which he has developed contain helium and oxygen, and may be applied in submarines or in high-altitude airplanes. Natural air is one fifth oxygen and four fifths nitrogen gas. The oxygen sup- ports life, while the nitrogen acts merely as an inert substance diluting the richness of the oxygen. By substituting helium gas for the nitrogen in about the same proportions, Dr. Hershey produced an artificial atmosphere in which mice and APRIL, 1930 guinea pigs flourished. The helium-oxygen atmosphere jg considerably lighter than air, A person might live comfort- ably inside the gas bag of an airship containing it. Pilots of high-altitude airplanes might breathe the prepared atmos- phere instead of concentrated oxygen, and it might be used to advantage in undersea craft. An incidental discovery in Dr. Hershey’s experiments was the fact that mice placed in an artificial mixture of pure nitro- gen and oxygen in the same proportions as in air li ed only a few days. Natural air con- tains about one percent of car- bon dioxide and rare gases, including helium, argon, krypton, neon, and xenon; and these were shown to be necessary for life in a nitrogen-oxygen mixture. PRINTING FINE FILIGREE ON RUBBER MATS RuBBER bath mats, table mats, and similar household objects susceptible to decoration can now be enhanced with all sorts of fanciful designs and turned out at a low cost by a process patented by Glenn H. Willis, of Akron, Ohio. The objects are made of hard rubber and may have designs of lace, fabric surfaces, tree leaves, stone surfaces, toy outlines, or almost any pattern traced upon them. - The crux of the process is a hard rub- ber mold, cheap and durable. Hard rubber is simply ordinary rubber with a high percentage of sulphur. In the un- cured state it is a soft, doughy mass. In making the mold of the Willis process, the object whose pattern is to be reproduced is placed in contact with a sheet (one half inch or so thick) of uncured hard rubber between the jaws of a steam-heated press. As the mass becomes heated it expands and flows into every nook and cranny of the “pattern” object. As curing pro- ceeds, the mass becomes hard. When the rubber plate is cured, it is taken from the press and the pattern object removed. Various color combinations can be used to brighten up the finished product. The complicated crochet pattern of a doily is reproduced in fine detail on a hard rubber mat.

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1930 The e is fort- f an ts of ight nos- ated ised rsea r in was 1 an tro- ame ynly -on- Car- ling 10n; sary ard ha un- the ced alf ber SS. ids the Apri, 1930 POPULAR SCIENCE MONTHLY 33 Step Plate Luggage Rack Here is a car equipped with new running board step plates designed to serve a double purpose. The plates . : z : are so hinged to the rim of the running board that 4 ae od they may be swung up to a vertical position to form a : i bide | convenient luggage holder. They are of sturdy con- i struction, with foot mats of heavy corrugated rubber. i A Limousine Side Car. This latest in motorcycle luxu- ries, exhibited in London, has an inclosed body with sliding roof and windows, leather upholstery, and dashboard conven- iences. At the rear is a luggage compartment which locks. % **Electric Eye’’ Detects Tunne! Fumes A —_ powries o for — the ventilation of ‘ Holland vehicular tunnel under the Hudson River be- Air Mail Catapult tween New York and New Jersey includes a photo- An improved portable catapult ap- “a4 e . * electric cell which detects the slightest haze of ex- paratus to enable a plane to pick : *, haust vapors containing deadly carbon monoxide gas, up air mail “on the fly” is shown as well as the presence of dust in the air. Above, at here during a recent test at Cur- left, is an interior view of the instrument from the top. ties Field. 1. ¥. A cond stretched In the left center compartment is the photo-electric : tube, and at the right is the light source with lens in between two masts is caught by a f eet aa 3 hook lowered from the plane. An ront. In the rear section is the amplifying equipment. instant later a mail sack attached to the cord is shot forward at about the same speed as that of the plane. ad New Headlight Tester. A pointer on the side of this test box is Tests Auto Drivers. In this Austrian invention a roller bearing a set to a number corresponding to the distance at which the lamp beam small map of city streets is rotated beneath a stylus. Operating a mini- should strike the road. The lamp is then tilted until two bands of light, ature steering wheel which controls the stylus, the candidate for a reflected on a screen at top of the box, coincide with two index marks. driver’s license shows his ability to thread his way through the streets. NEW IDEAS AND INVENTIONS

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34 INVENTS COMBINATION GLOBE AND ATLAS GLoBE and atlas are combined in the invention by a Los Angeles, Calif., map maker, of a model of the earth with a complete index and gazetteer inside it. Inserted in the globe are two small win- dows containing magnifying glasses. In- side is a mechanism that reels past this reading glass a fifty-one-foot paper tape bearing place names and descriptions arranged alphabetically. On this three-inch-wide strip are indexed 43,000 geographical names— more than ten times the number that it would be possible to print on a globe of this size. With each place is given its latitude and longitude, so that it may be located accurately upon the globe. A gazetteer on the same strip supplements the index with information about the population, area, industries, and other facts of all nations, states, and principal citizs. By turning the handle any portion of this information, printed in microscopic type, is brought beneath one of the mag- nifying windows for easy reading. Twen- ty-eight lines of type to each inch of strip make it possible to crowd 200,000 words of information into the entire roll. A special priating press was invented to print the roll in a continuous strip. It can print upon an unbroken spool of paper three inches wide and nearly two miles long when extended. MAIL BOX TELLS WEATHER AN ORNAMENTAL letter box that will not only receive letters but tell the temperature and atmospheric conditions is the latest equipment added to the One of the new ornamental mail boxes. Ther- mometer and barometer are inserted in base. POPULAR SCIENCE MONTHLY At right: The special printing press which turns out the paper tape index inclosed within the new globe- atlas. It can print a strip of paper nearly two miles in length. ee a - - agit - a $8 3 ae? F: Bas ro . Saal — The globe with built-in atlas, showing small window through which the index is read, and the handle for turning the index. At right: The globe cut away to show its interior mechanism. APRIL, 1930 postal service in Paris, France. Standing on a base that resembles that of the “dummy policemen” in use in many American cities, the large rectangular box is decorated on each face with a border of ornamental tiles. A cabinet let into one side contains a barometer, and slots around the base of the pillar accom- modate thermometers. NEW GRAVITY STANDARD FOR UNITED STATES Just how hard the earth pulls an object toward it is now being measured, by the United States Bureau of Standards, for the city of Washington, D: C. When the three or four year task is completed the United States will have for the first time a local standard of its own from which the force of gravity in any city of the United States, or the world for that matter, may be calculated. The exact value, known as small “g,” is useful especially to physicists. There is a slight difference between “g” in one place and “g” in another, caused by differences in alti- tude and other factors, such as the density of the underlying rock. Previously, according to Dr. Paul R. Heyl, Bureau of Standards physicist in charge of the measurement, the world’s only reference standard for gravity was that of Potsdam, Germany, from which all local gravity measurements were com- puted. Recently some doubt has been cast on the degree of accuracy with which this was originally measured, and conse- quently a new world standard is to be obtained which will incidentally check the German one. Dr. Heyl had previously completed the task of measuring what is known as Lig ‘‘G”’—the universal constant of gravity which, in one of Isaac Newton’s basic formulas, determines the attraction of any body for any other of known mass. This was the experiment in which he literally “weighed the earth” by observ- ing the swinging of heavy pendulums (P. S. M., June ’28, p. 24). The figure he obtained is important to astronomers in explaining the movement of heavenly bodies. This “G” is a universal quantity, Dr. Heyl explains, while the small “g” isa local one. TEST X-RAY SAFEGUARD X-RAYS in sufficient dosage attack healthy skin as well as diseased tissue. The problem for cancer specialists has been to get at the tumor without injuring the healthy outer skin. Recently Drs. Edith H. Quimby and George T. Pack of New York City described experiments in which they used various combinations of rays—for instance, hard and soft X-rays or hard and soft radium rays together. A real increase in the capacity of the outer skin to resist the effects of the harmful rays was demonstrated, they reported. API ars ~ — SS te A =

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ApriL, 1930 POPULAR SCIENCE MON SHLY 35 a Wheel Alignment Measured. When the front wheels of a car are run on to the two plates, shown above, a hand on the dial seen at the right indicates whether the wheels toe in or out. Wheels out of line move the plates, hooked up with the indicator hand. (See page 74.) Speedy Tank for Smashing Attack. This combina- tion tank and armored car will travel sixty miles an hour. Here, stripped of the endless treads, which can be taken off in a few minutes, it is being shown at the Capitol plaza, Washing- ton, to Representative Henry E. Barbour, of the House Sub- committee on War Appropriations. It carries only three men. Acetylene as Auto Fuel. Quick cold-weather starting, freedom from car- bon monoxide, more power, and economy are features claimed by the inventors for a new system of fueling a motor car. Acetylene gas, mixed with air and water, is fed into the cylinders instead of gaso- line by the carburetorlike apparatus secn in the circle above. The acetylene gas is carried in the tank on the bumper. Chemist Fights Deadly Gas. Dr. J. C. W. Frazer, of Johns Hopkins Uni- versity, shown above in his laboratory, has discovered a catalyst that will rapidly convert the deadly carbon monoxide into the harmless carbon dioxide. His process would rid city air of noxious fumes. NEW IDEAS AND INVENTIONS Testing the Carbon Monoxide Killer. At left is shown a car fitted with an experimental apparatus to test the efficiency of Dr. Frazer’s method of changing carbon monoxide to dioxide.

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36 The crystal ball sun-measuring machine at the Missouri Botanical Gardens. It makes an accurate record of the sunshine for each day. ST. LOUIS BOTANISTS MEASURE SUNSHINE HortTicutturists at the Missouri Botanical Gardens of St. Louis can now tell exactly how many hours of sun their flowers are getting. A sun-measuring machine, said to be the only one of its kind in the country, records the daily sunshine there with the precision of a mathematical chart. The apparatus consists of a large crystal ball mounted on a concave brass holder, the crystal acting as a burning glass to focus the sun’s rays on a sheet of specially prepared photographic paper lining the holder. As the sun crosses the sky, it leaves its mark on the paper as a line traced there by the rays transmitted through the crystal ball. The chemical coating of the paper is sensitive to sunlight. NOCTOVISION TESTED FOR SHIPS LOST IN FOG “NOCTOVISION,” a form of television that uses invisible rays to see through darkness, was demonstrated in New York recently as a possible aid to American ocean liners steering through fog. If favorable reports are made by the com- manders of three vessels, the Leviathan, American Farmer, and American Shipper, who witnessed the tests, the United States Lines may order one of the devices to be tried out at sea. The shipmasters saw the device pro- duce, on a screen, a clear pinkish image of a woman singer standing in total dark- ness in a room adjoining the laboratory. This device, invented by John L. Baird, British television inventor, employs in- visible infra-red rays. On the bridge of a vessel, it is claimed, the apparatus would enable the skipper to pick up the infra-red rays from harbor or vessel lights even through thedensest fog. It has already met with considerable success in British tests (P.S.M., Jan. ’30, p. 46). In one ex- periment it is said to have picked up the headlight of a motor car three miles away, through darkness and fog, although the light was hooded with a screen so that only the invisible infra-red rays passed through. POPULAR SCIENCE MONTHLY CEMENT IS SHOT ACROSS RIVER IN AIR TUBE ENGINEERS recently were confronted with the problem of how to get cement across the Allegheny River, in Warren County, Pa., for a sixteen-mile highway. They solved the puzzle by slinging a three-inch pipe, 768 feet long, from the freight cars on one side of the river to the mixing station on the other. A cable suspended it above the water. Com- pressed air at 100 pounds’ pressure shot the entire supply of cement used in build- ing the road through the pipe. FINGER MOISTENER, IN PALM, HELPS CLERKS SPEED and convenience are provided in a new finger moistener designed for those who handle loose papers. A small felt pad, mounted on a water reservoir about the size of a wrist watch, fits tightly into the palm of the hand, the combina- tion itself being clasped to the hand by a spring grip which does not hinder finger ome? od Hidden in the palm of the hand, this device makes moistening of fingers quick and easy. movement. Thus the middle finger may reach down into the palm and be moist- ened while at the same time the hand asa whole is left free. Fumbling and the unsanitary habit of moistening in the mouth are eliminated. Besides being valuable for bookkeeping machine operators who wish to pick up ledger sheets quickly and easily and for those who file papers, the device is con- venient for moistening envelopes. NONPOISONOUS DYES NOW PAINT THE LILY PAINTING the lilies is now an established fact, thanks to scientific research. Cut flowers have been colored artificially for some time past, but most common dyes are poisonous to the flowers and make them wilt almost immediately. Now, according to Dr. R. B. Harvey, of the Minnesota Agricultural Experiment Sta- tion, some brilliant, nonpoisonous dyes have been discovered. Sweet peas, for example, are colored a brilliant blue five minutes after the newly cut stems are placed in a water solution of APRIL, 1930 the dye. Lilies and carnations are also colored by the new dyes. It is also found that flowers so dyed behave somewhat like photographic plates, and that miniature portraits, initials, or messages may be imprinted by light upon the dyed petals. PROOF OF PARENTAGE IS FOUND IN BLOOD FouUNDLINGS who are uncertain whether they have discovered their parents need no longer despair. A sure proof of parent- age based upon the laws of colloid chem- istry has been found, according to Profes- sor Wilhelm Zangemeister, of Kénigsberg University, Germany, who would rely upon reactions between minute particles in the blood serum of the child and the supposed parent to confirm the relation- ship. ; Blood serum is classed as a colloid, colloids being gelatinous or “‘gluey”’ sub- stances. Professor Zangemeister believes some specific colloidal substance is handed on by the parent to the child, and that this substance may betray its presence in test tubes filled with the serums if a powerful light be shot through them. NEW DEVICE SUPPORTS BIKE IN TRAFFIC A CONVENIENCE for bicycle riders has recently been invented by a German experimenter. It is a device acting as a bicycle rest, especially handy when there is a traffic hold-up. Like a humpbacked roller skate in appearance, it fits beneath one of the pedals. Releasing a lever per- mits the roller frame to reach the ground and when the rider stops, he can park sol- idly in the roadway. But the contrivance also offers unlooked-for possibilities in another field of action. Should the rider, when wheeling merrily along at a fast pace, accidentally release the mech- anism, it would suddenly hit the road and send the astonished cyclist sailing over the handlebars. cae : 2 ss ahs RR He RE ee MER x ae When pressed against the ground this German invention serves as a rest for the bicycle.

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ApriL, 1930 POPULAR SCIENCE Section Freight Car Cuts Loading Time. This new railway car, recently shown in Chicago, is designed to do away with two of the steps in handling freight under the present system, as each’ section in the car unit can be trucked to the factory for loading or unloading. oe a a Motor Takes Place of Pin Boy. On the North German Lloyd liners Bremen and Europa, electric motors have been installed in the bowling alleys to set the pins, each of which js controlled by a string. The machine also returns the ball to the player and indicates the score. NEW IDEAS AND MONTHLY Refueling While Race Is On. Outboard motor racers, as shown above, can take on fuel without stopping. A fuel boat equipped with a pump, a hose, and a long pipe attached to its tank draws alongside the racing boat. The pipe is swyng over the racer and fuel is pumped into its gasoline tdnk. In the oval is shown the first refuel- ing motor boat, preparing for a test run at Oakland, Calif. Fish Now Travel in De Luxe Car. The all-steel Pullman shown here was built for the United States Bureau of Fisheries and will carry 500,000 one-inch fish designed to stock the lakes and streams of Amer- ica. E. C. Fearnow, the Bureau’s superintendent of distribution, is seen holding a fish container. The car has kitchen, dining room, boiler room, berths for the crew, and special compartments for carrying the fish. INVENTIONS ee eel = ee Se aed ay asea thar a Sa 4 if

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ae eo 38 POWERFUL RAY TUBE TO BOMBARD THE ATOMS New hope of smashing atoms open to see what is inside is brought by a novel vacuum tube developed at the California Institute of Technology by Dr. R. E. Vollrath. Although it uses only 250,000 volts of electricity—terrific pressure by ordinary standards, but little enough for atom-wrecking attempts—it is as power- ful as other tubes of a million volts. Speeding electrons which it emits collide in the apparatus with highly charged vapor of mercury to augment their own power. Eventually the equivalent of a power of five or six million volts may thus be available. It was long imagined that shattering atoms might loose titanic sources of power—might even wreck the earth in a great explosion. Recently Dr. R. A. Millikan, noted California Institute of Technology physicist, put such hopes and fears to rest. Atomic power is probably a myth, he said; the universe is ‘‘fool- proof.” Nevertheless, scientists would like to take atoms to pieces, among other things to see if they could transmute one element such as silver into another such as gold. The California experimenters, under Dr. Millikan, have already built several high-power tubes, possibly fore- runners of one that will smash the atom. A 1,000,000-volt tube built last year pro- duced rays that could be detected 300 feet away. ‘ HALF OF WORLD’S RADIO SETS IN AMERICA THERE are 21,629,107 radio receiving sets in the world, nearly half of them owned in the United States. This esti- mate shows that there is one receiving set for every twelve and a half persons in this country, as against one for every fifty-three persons in Europe. These figures were quoted by the Elec- trical Equipment Division of the Depart- ment of Commerce at Washington. In addition to these facts the radio industry has few dependable data. For instance, the estimates of the number of sets sold during 1928 range all the way from 2,500,000 to 3,500,000, and the guesses for 1929 are even wilder. This gap in radio information will soon be filled. Bracelet wich bracket which clasps around the wrist and holds magazine or book for reading. POPULAR SCIENCE MONTHLY Dr. R. E. Vollrath, of Pasadena, Calif., with his vacuum tube that furnishes five million volts. PAWPAW TREE FURNISHES FOOD, SOAP, MEDICINE In THE tropical mazes of South America grows a remarkable tree having a variety of uses both economic and medi- cinal. This is the papaya or pawpaw tree, to be distinguished from its cousin in the central and southern United States which belongs to a different family. The tree is an odd-looking affair, tapering from the base of the stem to a height of about twenty feet. It exudes a peculiar juice which, rubbed on meat, will make the toughest beefsteak as tender as venison. The natives living in the districts where the pawpaw tree abounds use the juice for this purpose. In Paraguay the pawpaw leaves are used as a substitute for soap. The juice of the tree contains fibrin, a chemical protein elsewhere found only in the animal kingdom. However, the Field Museum of Natural History, in Chicago, which has one of these trees in its botany exhibit, states emphatically that the tree is not to be regarded as a link between the animal and vegetable worlds. The juice is an acrid, milky substance and has medicinal value. The seeds are used as an effective vermifuge or worm destroyer. Furthermore, the tree has a delicious fruit. It is large, pulpy, ob- long in shane, and has a heavy rind. HANDY BRACELET SERVES AS MAGAZINE HOLDER WuaT might be a convenience to readers is a unique wrist attachment re- cently designed for holding magazines and small periodicals open before the eye at arm’s length. This novel book holder is a bracelet fitting snugly about the forepart of the wrist, to which is fixed a small bracket firmly supporting the periodical just as the “lyre” of a cornet supports sheet music. The device is adjustable to any wrist, and may be obtained in sterling silver or nickel, silver, or gold plated. APRIL, 1930 SHOOT POISON DUST TO KILL MOSQUITOES Two battles in which no quarter is asked or given are man’s fights with in- sects and disease. These are combined when communities fight mosquitoes, for these- insects are not only annoying in themselves, but some kinds of them do enormous harm by spreading the germs of malaria. Poison gases and other chemicals, widely condemned in human warfare as too barbarous for use, meet with full ap- proval. Several years ago mosquito- fighting experts used airplanes to sprinkle a poisonous dust over infested areas. For the coming summer the malaria experts of the United States Public Health Service will use blowers, mounted on boats or automobile trucks, to scatter the dust. The dust used is Paris green, a chemical compound of arsenic and copper, diluted with about eighty-five percent of slaked lime. That this is effective against the insects is due to the habits of the mosquito’s child. Out of mosquito eggs hatch tiny larvae, many of which can be seen on the surface of an infested ditch or pool. These are the “‘wigglers.”” They seek the sur- face of the water to breathe, for these larvae are air-breathing, although they live in water. The poison dust scattered by the new machines floats on the water surface. Wrigglers coming up to breathe get some of the dust into their bodies Numerous and unlamented deaths result. NOVEL LIP FORM JUST STAMPS ROUGE ON RAQUEL TorrEs, the famous film star, is responsible for a new device for lip rouging. A wooden stamp, shaped to the form of the lips and covered with rouge, is pressed against the lips, thus stamping the rouge on. The stamp comes in various sizes, to fit the lips of small as well as large featured persons. Raquel Torres demonstrates the use of her lip-shaped wooden stamp for applying rouge.

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Aprii, 1930 POPULAR SCIENCE MONTHLY 39 What We Burn Up Every Year Ine 208 2, 062, ,800, 000,000 CU.FT. OF_- AS, NATURAL ANO ARTIFICIAL, » PRODUCED IN ONE YEAR AVOULD FILL A ZEPPELIN O IN DIAMETER AND T\ENTY MILES LONG ef: HUDSON RIVER . cial . DIL BURNED IN ONE | : EAR WOULD TAKE | HOURS 43 MINUTES> FO RUN OVER NIAGARA ‘Wai? LS,OR WOULD MAKE A KE a FOOT DEEP COVERING AN REA OF 173 SQ. MILES” , MANHATTAN ISLAND _- SUCH A SHIP COULD LI SUE AND WELGi PTA LEVIATHAN FOR AN ANCHOR OVER NEW YORK, THE AIRSHIP WOULD OVER- SHADOW ALL OF MANHATTAN ISLAND AND DARKEN AN AREA EXTENDING MORE THAN SEVEN MILES FARTHER UP THE e THE 543,477, 954 TONS OF © COAL SURNED YEARLY \VOULD a C -. sh BN i XX Fa Ma, ~e— (1). The total energy in gas burned in the United States in a year would run a 530,000-horsepower turbo-generator and supply electric light to New York, Vermont, and New Hampshire for 176 years. (2). A 3,300,000-horsepower turbo-generator could (3). The energy in gasoline and oil burned in be driven by the energy in the coal burned in this America in a year would run a 1,000,000-horse- country in one year, and this could supply light to power turbo-generator and supply light to New the entire United States continuously for 176 years. York and four neighboring states for 176 years.

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| | i; = = rad 4) “4 te Sy ee rs temamery wewene meee we et Py HAT do representative Ameri- cans think of PopULAR SCIENCE Monrtuiy’s annual award of $10,000 for the year’s outstand- ing achievement in science? Scientists, inventors, and engineers; statesmen, educators, and clergymen; industrialists and business executives have expressed their opinions since pub- lication, in the February issue, of the announcement of the creation of the award and the formation of a committee of distinguished scientists who will select the accomplishment which, in their judg- ment, is of greatest potential benefit to the world. The comments of these men are espe- cially significant because they present a lively discussion by some of the best minds in the country of the value of prize awards in general and their merit as a stimulus to scientific endeavor in par- ticular. A vast majority of those giving their reactions were enthusiastic. They agreed unreservedly that the award—the largest single monetary prize of its kind in America—by recognizing and focusing ublic attention upon the unselfish abors of scientific workers and rewarding superior attainment, will serve as a real incentive to scientific and inventive effort. A few, while commending the magazine for its intentions, voiced apprehension that its hopes would not be realized. Most of those who were not enthusiastic objected on the ground that scientific endeavor has not been and will not be stimulated by monetary reward or hope of gain. This, like most generalizations, is only partly true. PopuLAR SCIENCE MONTHLY APRIL, 1930 1872 et _ 1930 Our $10,000 Prize Will Do for Science has never held that by giving each year $10,000 to some worker in science it could make scientists work harder, achieve more, or even bring more recruits to their ranks. No one who is willing to de- vote his life to science for the betterment of his fellow men or for the satisfaction of his own inclinations needs the spur of such a reward. Nor would $10,000 urge on to greater effort the man who sees millions for him- self if his invention succeeds. What the award can do, and what PopuLaR ScrENCE MONTHLY insists it will do, is to focus the attention of the public on those who, for any reason at all, are laboring to accomplish results that eventually will be of benefit to the public—of greater benefit fhan they can ever be to those who accomplished them. More and more, as industrial civiliza- tion progresses, the daily lives of men are ruled by, and even founded on, science. There is almost nothing that civilized man does, nothing that he uses, that is not somehow dependent on the works of science. It is to impress this fact on the public, even more than to reward or stimulate scientific endeavor, that the PopuLaR ScrENCE Montuty Annual Award has been instituted. If, therefore, the award does nothing more than em- phasize this fact, it will have justified its creation. No one is in a position to speak with more authority on this subject than America’s distinguished scientist and inventor, Thomas A. Edison. To the project he has given his unqualified ap- proval and expressed his entire confi- dence in the benefits to science and man- kind that are bound to result from it. "E. HAS been a source of much pleasure to me,”’ Mr. Edison wrote, ‘‘to read the announcement of the recent creation by Popular SCIENCE MONTHLY of an annual award of $10,000 for the year’s achieve- ment in science that shall be adjudged of greatest potential benefit to mankind. To my mind the establishment of this very liberal annual award is a highly com- mendable example of the public spirit displayed by PoPULAR SCIENCE MONTHLY in seeking to stimulate the activity and aid of investigators in the realms of science and research. I have no doubt that the working out of this plan, in prac- tice, will result in great benefit to man- kind. Allow me to congratulate you on the great incentive you have offered to scientific workers, and also to compli- ment you on the fine personnel of the Committee of Award which you have chosen.” The majority’s view of the award is strikingly epitomized by Secretary of the Interior Ray Lyman Wilbur, formerly president of Stanford University, Cali- fornia, and noted for his work as a physiologist and educator. “We need to have science and its work appreciated,” he wrote, “since the future of our country depends upon the proper relationshin tetween science and de- mocracy.”’ > BW Z SS SS

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Famous Men Tell What They ‘Tiiaik of Porputar Science Monrtuty’s Annual Award for Outstanding Achievement in Science Among leading American men of science who whole-heartedly endorsed the crea- tion of the award is Dr. Ambrose Swasey, of Cleveland, O. Dr. Swasey, founder of the Engineering Foundation, is the builder of most of the great telescopes in this country. He is the inventor of the Swasey range and position finder adopted by the United States Government. “Tt gives me much pleasure to express my appreciation of the institution of your splendid award,” wrote Dr. Swasey, ‘“‘and I am confident it will prove to be a won- derful incentive in the realm of scientific research. “No doubt the consciousness of notable achievement is the greatest award that can come to one; yet the recognition of such achievement by those eminently qualified to pass judgment in that partic- ular field of scientific research, must be especially gratifying and inspiring. “Tt is indeed most fortunate to have lived in the marvelous age of discovery and development in science, from the time of Bell to Marconi, from Pasteur to Curie, and from Langley to Lindbergh; and I firmly believe that in the coming half cen- tury even greater storehouses of knowl- edge will be unlocked by the scientists for the good of mankind.” Typical of a great number of con- gratulatory messages was the comment of another member of President Hoover’s cabinet, Secretary of Labor James J. Davis, who said: “T heartily endorse your movement to reward with a medal of honor and with a handsome purse each year the scientist or inventor whose work has accomplished most for humanity. It is to the everlast-

ing glory of our great scientists, inventors, and engineers that they have never wait- ed for such recognition, but have devoted themselves to their labors not only with- out fit remuneration but often at serious cost to their physical and material well- being. On that very account itis high time that their achievements for human- ity should be singled out for suitable honors, accompanied by substantial finan- cial aid. Humanity needs to become better acquainted with those who add to its knowledge, safety, and comfort. Your plan for an annual award is a timely step in that direction.” Among the opinions of leading scien- tists who are in complete accord with the spirit in which the award was created, that of Dr. Michael I. Pupin, inventor and professor of electromechanics in Columbia University, New York, is representative. “The creation of the award,” wrote Professor Pupin, “is a splendid move in the direction of enabling gifted but im- pecunious scientists to provide themselves with means for continuing their splendid efforts.” Dr. C. E. Kenneth Mees, director of the research laboratory of the Eastman Kodak Company, Rochester, N. Y., was one of the small group of distinguished men who expressed doubt of the award’s efficacy as an incentive to scientific effort. “I cannot imagine any scientific man to be stimulated to do better scientific work by the possibility that his work might receive a cash award at the end of the year,” Dr. Mees wrote. ‘Nor do I think it is possible to tell at the end of the year what work done in the year ending

Z4 /. 4 <2 y Zn ZZ Z Decoration by Franklin Booth three months before will be of greatest potential value to the world.” A view almost exactly opposite to that of Dr. Mees was given by Glenn Curtiss, aviation pioneer, who said: “Allow me to compliment you. I think this is the best possible way to stimulate invention. “In the early days of aviation it was the cash prizes offered by the World, Herald, and Times that made possible the experimental and research work which led to the development of the hydroaeroplane and the flying boat.” Agreeing with this opinion, J. F. Callbreath, secretary of the American Mining Congress, said: “T can conceive of nothing more help- ful than such a plan as you have put in operation to stimulate scientific research.” Like Dr. Mees, Dr. Gustav Lindenthal, famous bridge building engineer, objects to the designation of a year as the period during which a piece of scientific work worthy of- distinction may be both achieved and brought to light. “T do not favor the notion,” wrote Dr. Lindenthal, “that there must be an award annually to someone for con- spicuous progress in some field of science. Conspicuous progress in any field of science depends upon exceptional men- tal qualities of some individuals. They do not appear annually or in other regular periods.” (Continued on page 137) ahagiontbeberida dk ehdedanpeende aaa 1 4 |

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42 POPULAR SCIENCE MONTHLY Here are the man, the camera, and the plane just back from an air map making trip in the clouds. How Air Camera Men Map Unseen Places By CHARLES BOXING match was scheduled for the evening in a Coney Island, N. Y., stadium. It was already noon, and soon tickets were to be placed on sale. The promoter of the match looked for the floor plan to show purchasers their seats. He found to his consternation that there was no floor plan. Fortunately it was a beautiful, cloud- less day. Luckily, a friend of mine hap- pened to hear of the promoter’s plight and had our office on the phone at once. Early in the afternoon, an airplane soared over the grandstand, dipped low, and scudded away. An hour or two later an aerial photograph lay on the promot- er’s desk. It showed in clear detail every row and seat. Hurriedly labeled with pen and ink, it became the floor plan for that evening and for many that followed. That was the simplest air-mapping job we ever did, since it needed only a single photograph. But in the six years that I have been in the air-mapping business, we have made maps that required thousands of separate pictures. By a specialized process they were dovetailed together with a degree of accuracy of tetter than one percent. Such accuracy meins that enlargements must match within a hun- dredth of an inch. F. KEALE, JR. Why map from the air? First, because there are certain purposes for which only air maps can be used. Second, because for all kinds of mapping it is fast and in- expensive. Third, because an aerial map of a city, for example, shows buildings, streets, and houses with a clearness that no other type of map can approach. VEN a person who has lived in a city a long time can learn something about it from an air map. A young man told me the other day of discovering that each Sunday morning for months he had walked two blocks out of his way through the crooked streets of Greenwich Village, a district of New York City, in order to reach his favorite breakfast place. An aerial map of New York showed him that by starting in another direction that seemed wrong he would actually get there sooner. The firm which I head, the Airmap Cor- This photograph of a Coney Island, New York, stadium, taken from the air, was enlarged and used as a seating plan in an emergency. APRIL, 1930 poration of America, makes two kinds of air maps—“‘oblique,” with photographs taken slantwise from the plane, giving a “bird’s-eye view” in perspective—and “vertical,” with the camera pointing straight down. Unusual requirements sometimes make the first kind preferable. c= time at a banquet of public utility officials in Brooklyn, N. Y., I brought up the idea of air-mapping the borough. An official of the local electric company was interested; he wanted to know whether we could make a series of photographs that would show among other things the type of building in each section. The company was considering a change in the kind of electricity it sup- plied its customers, and knowing whether a certain section contained frame houses or industrial buildings would aid in fore- casting the type of service required. I made a few sample photographs taken vertically, but they did not show the style of building plainly enough for the company. So we contracted to make, instead, a complete survey ef Brooklyn using oblique photographs. We took the door off a cabin plane, because the win- dow was too high for good photography, and started shooting. To make oblique pictures, the pilot would tilt the speeding plane on its side while Eric F. Dixon, head of our photo- graphic department, crouched on his toes and fired away through the open door. That was how we almost lost one of the best aerial camera men in the country. Everything was going fine when the plane hit a bump in the air and Dixon started out the open door. I guess he thought he was never going to see his two pairs of twins back home in Hanover Neck, N. J., again. A quarter inch of his elbow, he says, was all that saved him from going out. After that we built a special door for the plane, with a safety window in it, to finish the picture-taking job. When we were through we had a book of maps that showed how many stories every house in Brooklyn had. The vertical maps are the ones mostly used, and we get some queer orders. For instance, a railroad in New Jersey, serv- ing an iron mine, was charged by the Interstate Commerce Commission with maintaining excessively high rates. The Commission based its claim on the alleged fact that the railroad was serving a populated suburban area. We were engaged by the railroad to make an air map of the route. No better evidence. could be needed of the bleak, desolate, uninhabited region through which the a cy ay | ee

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APRIL, 1930 tracks of the railroad passed. Recently we completed an entirely different kind of map jor the Government—a survey of the Mississippi River delta where the river enters the Gulf of Mexico. The pictures, showing the course of the river water through the to;tuous channels, will be used to aid in flood -ontrol work. To photograph the course of the muddy Mississippi water far out into the Gulf, we flew land planes as far as five miles offshore— thirty-five miles from a safe land- ing place. A forced landing would have meant all kinds of trouble, but none was necessary. In our six years of flying we have had no accidents, and only one forced landing, made without difficulty, when a motor quit right after the take-off. NE reason we don’t have trouble is that we are “fair weather flyers.”” We don’t go up unless the day is fine for pictures, and that means fine for flying, too. Even in summer we can count on only one good picture-taking day out of five. In winter it’s only one out of fourteen. Sometimes the perils of air mapping are worse on the ground than in the air. The story is told of a pilot and a photographer sent up to the Adirondack Mountains, in New York State, to map a route for an electric transmission line. They had the job all but finished when a spell of bad weather set in. For about three weeks they sat around doing nothing whatever. One night the pilot went to a show. Directly after the show he mar- ried one of the actresses. Next day dawned clear and fine—and no pilot. Before he appeared at the landing field, the bad weather had shut in again and continued for three: weeks more. Sometimes if the weather is not too thick we can take pictures in spite of it. When we air-mapped Allentown, Pa., to aid the civic author- ities in planning the outward POPULAR SCIENCE MONTHLY growth of the city, we struck heavy haze. By using a special screen on the camera lens, that cut through the haze, we were able to get good photographs of the ground when it was actually invisible to the naked eye from the plane. The screen is a piece of colored gelatin that allows

These three pictures sho w various steps in the process of making air maps. The strip above shows how the photos over- lap so that only the directly vertical part of each exposure is used. Directly above is an air view of Allentown, Pa., made with a special screen when the town was hidden in haze. At left is the index map used in order to get the hundreds of air pictures correctly placed. Here the overlapping of separate photos, which are numbered, can be seen.

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All photos courtesy of Airmap Corporation of America. Here is how the Mississippi River looks to an aviator high in the air above it. The picture was taken as one of a series made to aid the Government in its efforts to control the floods in the neighborhood of New Orleans, La. only the long light waves that penetrate fog to pass through it to the film in the camera. Even in good photographic weath- er, a yellow screen is often used in front of the camera lens to clear up the atmos- pheric haze, its action being a little weaker than that of the special screen. One thing that air mapping has done is to revolutionize the methods of “timber cruising.” When a paper company negotiates for a tract of land containing standing timber, it wants to know how much wood it can get out of the land. The old way used to be to send a man known as a “timber cruiser” through the tract. He would stand on top of a hill and try to guess how many trees there were in the surrounding territory. Sometimes his guess would be right, but more often wrong. Nowadays an aerial photographer flies over the land and takes pictures from which an exact estimate can be made. In winter they even show whether the wood is hard or soft; the softwood evergreens stand out against the snow. |” aay vamos an air map is a highly developed art. A good example of the way that it is done is the tax map which we made of Nassau County, Long Island, N. Y.—one of the “biggest jobs ever done, requiring 3,000 separate photographs. ‘ An airplane map often reveals houses and lots that never have been discovered by the local tax collector, and that will bring a city thousands of dollars of added revenue. But in Nassau County the need of an up-to-date map was even more acute. The country had suddenly blos- somed out with real estate developments. There was no tax map in existence. The new administration was confronted with the prospects of (Continued on page 155) UN te am tg i <he nS S n ece e 8 ce E

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Ee eae i Le ee ee ee ee ea ey hie 44 Took8 Hours POPULAR SCIENCE MONTHLY © APRIL, 1930 Louis Daguerre gave up wealth and fame to follow, for fifteen years, the fantastic dream of “painting pictures by sunlight.” Y Now-20,000 in a Second “1c pavis N 1830, it required eight hours to take a photograph. The other day, Baron C. Shiba’s remarkable camera re- corded 20,000 pictures in one second (P.S.M., Nov. ’29, p. 31). In this dramatic advance, which has taken place within a single century, a Parisian painter of stage scenery and a magic cupboard in his home workshop laboratory played leading roles. The painter was Louis Daguerre, who made photography practicable. Before his time, a few indifferent pictures had been made by the painfully slow process of exposing asphalt-covered plates all day and then treating them with solvents. One day Daguerre exposed an iodized silver plate. From shortness of expo- sure or dullness of light, it showed no trace of an image. Intending to recoat the plate and try it again next day, Daguerre placed it in an old cup- board. The next morning he was amazed to find on it a distinct image. He put another underexposed plate in the magic chest. At the end of twenty-four hours, an image had appeared on that plate also. Then the experimenter went to work to find which of the chem- icals stored in the cupboard was responsible for this unexpected development of the plate. In the end, he found mercury was doing the work. This accidental dis- covery of the effect of mercury upon the exposed plates cut the necessary time of exposure from hours to minutes. After a dozen years of ceaseless labor, a lucky moment aided Daguerre’s suc- cess. AGUERRDP’S life, in its ups and downs, its dramatic turns of fate, reads like a ro- mance. He was born in 1789, the vear of the Revolution, in the little village of Cormeilles, near the mouth of the Seine. As a child he was neglected by his parents and ran ragged through the public square. Now in that square there stands a monu- ment, raised by grateful artists from all parts of the world, in memory of his re- markable achievements. For a time, Daguerre worked as an inland revenue officer. Then, without friends or money, he set out for Paris to make his fortune. By native ability, he became the leading scene painter for the French stage. His original mechanical effects were the talk of Paris. His “diorama,” a gigantic painting exhibited first in reflected and then in transmitted light, gave the weird impression of the same scene perceived first in sunlight and then in moonlight. The French Academy of Fine Arts made him a member. His days of struggle apparently were over. He had become rich and famous. At this point he began to neglect his work, to spend his days and nights laboring in a little home workshop, to fuss with ill- smelling chemicals and queer looking Daguerre’s cabinet of chemicals ended a twelve years’ search and revealed to him, by chance, a secret which led to modern photography. apparatus. He began to slip back into poverty and hardship in order to follow a dream—a fantastic dream of painting with sunlight. Frok years, in his scene painting, he had employed a camera obscura to sketch from nature. This dark box, having a lens-covered aperture through which light from external objects entered and formed their image on the side of the box op- posite the opening, had been familiar to artists since the time of Leonardo da Vinci. About the middle of the sixteenth century the Italian philosopher, Porta, had invented it. Crowds had flocked to his home in Naples to see the wonder. Wealthy Italians of the time built little dark rooms on hilltops to form private camera obscuras where, with friends, they viewed images of the countryside on the darkened walls. In its mechanism, the human eye is a small camera obscura, and ail modern cameras are adaptations of Porta’s discovery. For three centuries, artists, using this apparatus, longed to make per- manent the fleeting images painted within by sunlight. This Daguerre set out to do. Friends told him it was im- possible. Reputable scientists called the plan as futile as an attempt to capture a mirage. Sir Humphry Davy, English chemist, had tried and failed. Yet, without previous scientific training, the scene painter strug- gled on, undaunted. When his fortune disappeared and he con- tinued to work at the seemingly hopeless task, his wife consulted a physician, fearing her husband was losing his mind. That was in 1825. For four- teen years more, Daguerre worked ceaselessly, until, in 1839, he was able to announce his great discovery. Other ex- perimenters, Sir Humphry Davy, Thomas Wedgwood, Joseph Niepce, paved the way for him, perhaps. But it is to this (Continued on page 145) a Li «ae A oe ee | 6 eee 6 ee oe ok

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Aprit, 1930 POPULAR SCIENCE MONTHLY 45 PROGRESS.AND DISCOVERY I —s achievements in engineering, exploration, and dis- ‘overy, and the latest news of the world’s progress in science Aircraft Carrier’s Power Lights City for a Month A Navy aircraft carrier supplied electric light and power to the city of Ta- coma, Wash., for thirty days in a recent emergency at that port. When an_ unprece- dented drought cut off the water supply to turn the tur- bines in the municipal hydroelec- tric power plant, a distress call to the Navy brought the electric- driven aircraft carrier Lexington to the rescue. With the Lexington anchored thirty feet from the dock, twelve cables were strung to the ship and connected to 180,000- horsepower generators. The other end was switched into the city’s power sys- tem, and the vessel’s dynamos set hum- ming. Electric current sped through the cables to aid the city plant’s supply, and the city’s main industries, many of them shut down for lack of power, quickly swung into action. The novel hook-up continued for about a month, until rain and melting snow restored the water level behind the city dam. Easily equal to the task was the Lex- ington’s electric power plant; any one of its four generators alone was capable of supplying the current needed by the city. At full power the warship’s plant. could supply the power needs of a city twicé the size of Washington, D. C., Navy officials estimate. It would carry ‘the simultane- ous load of fifty heavy electric trains, or would light more than 6,000,000 fifty- Full: power is used watt electric lamps. to drive the ship at its high speed, which is estimated at approximately forty miles an hour—almost as fast as the average railroad express train. Rhythmic Noisés Speed Up Workers’ Output EFFICIENCY experts are turning to mu- sic to..aid modern industry. and .man- ufacturers: may~ soon -‘find “it to- their advantage to put brass bands.and perhaps entire symphony orchestras on -their pay rolls:- Rhythmical’ sounds ‘produced. by various instruments in time with. the movements of workers during a recent experiment in an English packing ware- house is-reported to have iricteastd their output twenty*percent:. Production dropped sharply When the sounds were ‘jazzed up”’ so as to be out of time with the motions of the factory hands. A Ps At left: The Lexington delivering 20,000 kilowatts of electricity into Tacoma’s municipal power system. In circle: Sailors operating ship’s power plant controls. Above: The huge transformers to which the Lexington’s turbo-generators were connected. similar experiment in a spinning mill is said to have inereased output fifteen percent. Many experiments of this kind have been made in the United States. The Bush Terminal Company last year in- stalled a radio in its offices at Brooklyn, N.Y., and officials advocate the tuning-in on jazz music because they have found it speeds up the work of the typists (P.S.M.., Feb. ’29, p. 62). Nation-Wide Survey to Fix Exact Locations To FIX on maps the exact position of every portion of the United States’ vast territory is the aim of the United States Coast and Geodetic Survey. The entire 3,000,000 square miles of the coun- try will then be brought within the in- closure of the Government survey’s great triangulation system. So William Bowie chief of the geodesy division of the survey, recently reported to the National Acad- emy of Sciences. Geodetic surveying, the most accurate of alk: surveying, deals with large areas and takes into account the curvature of the earth’s surface. The territory to be surveyed is divided into several triangles and the arms of the triangles calculated. By, continuing the process until the whole area is covered with a network of trian- gles, the location of all important points throughout the country can be accurately determined. This is known as_ the oa = Sores eee se i

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ee ae ee 46 triangulation system. Government survey stations now dot the countryside all over the United States, Canada, and Mexico. The central station is at Meade’s Ranch, Kansas. The Wilk Comet Parades before the Telescope Tue latest of the heavenly bodies to have its picture taken by astronomers is the Wilk comet. The above is a three- time enlargement of the original photo- graph taken recently at the Yerkes Ob- servatory, Williams Bay, Wis., by G. van Biesbroeck. The comet’s tail, starting as a sharp How Much Do You Know about Physics? Tet your knowledge with these questions, chosen from hundreds asked by our readers. Answers are on page 143. 1. Would it be possible to siphon water from an ele- vation of 1,000 feet over an elevation of 2,000 feet high into a valley at sea level? Does gravity act in a par- | tial vacuum? | Is it easier to swim in deep | water? | } How is the horsepower of | an engine measured? If water boils at 212 de- | grees, how could the ther- - PP PP mometer on my hot water boiler register 220 degrees? 6. How can I measure dis- | tance by sound? 7. What happens to energy used up in friction? . Is there any substance that will insulate against | magnetism? 9% Why does a diamond sparkle more than a piece of glass cut and polished in the same way? | 10. How does a fireless cooker work? POPULAR SCIENCE MONTHLY spike from the side of the comet opposite the sun, spreads out in a stream of star dust that gradually fades. The central beam carries straight on over a length of two astronomical degrees, or a mere mil- lion miles. The countless white stripes across the picture represent stars and their changing positions during the long exposure of the plate. A comet’s tail races along ahead, proving that its material is repelled by the sun after being ejected from the whirling mass. Comets travel in long ellipses, sometimes retracing their paths. The famous Halley’s comet has made three appearances since 1682. New Composition Hard as Flint, Flexible as Paper Dr. Hal T. Beans, of Columbia University, testing toughness of flexible phonograph records made of new chemical composition. A REMARKABLE chemical composition recently developed promises, among other things, unbreakable phonograph records that can be stamped with the speed of a printing press and sold like papers on the news stands, as well as a fire- and water- proof varnish substitute, especially valu- able on airplanes. Developed by Dr. Hal T. Beans, pro- fessor of chemistry at Golumbia Uni- versity, this composition represents the climax of a search conducted by chemists for years to find a material of such flexi- bility and toughness. A thin film of the stuff, so tough that a hammer blow will not break it, is as pliable as a sheet of paper. It is really a synthetic resin, with- out taste or odor, in appearance a clear amber substance with a polished surface. Hardening quickly from the liquid state, it is highly resistant to heat, and is said to be ideal for molding and stamping processes. Even matrices for casting metal type can be made of this composi- tion. As a liquid it is noncombustible, and accordingly is useful as a coating for the nonmetallic parts of airplanes, on which it can be sprayed. It may even invade the world of the APRIL, 1930 “talkie,” replacing the fragile material of which talkie disks are now made. If the claims of its producers are justified, the new compound may effect a drastic price reduction in various manufactured com- modities. - “Tee Fans’’ Cool French Railway Coaches IN FRANCE, hot, stuffy railroad trips are to be banished next summer by artificially cooled cars. In preliminary experiments last year the first of these novel trains, on a trial run of several hours from Paris, maintained a tempera- , ture of about sixty-eight degrees Fahren- heit despite the heat. A compartment at the end of the car holds tanks containing 500 pounds of ice. Chilled air drawn between the tanks is blown by a fan through a duct running the length of the car, escaping from out- lets into the passenger compartments. Wooden latticework on the roof of the car insulates it from the hot sun. The railroad developing the system plans to “‘refrigerate’’ all its coaches, regardless of class. ‘Spinning Wheel”’ Bottles German Soft Drinks No, not an old-fashioned spinning wheel, but a “bottling” wheel is the strange contraption pictured below. It is used for putting corks into bottles of fruit juice concocted in a nonalcoholic brewery in the province of Thuringia, Germany. Evidently there are other drinks in Ger- many besides beer, as the making of tasty prohibition beverages from fresh fruits is a process of some importance in this district. The hub of the wheel for bottling the finai product has cups resembling electric light sockets to receive the necks of the bottles. From the rim of the wheel springs press down on the bottoms of the bottles to effect the sure plugging of the corks. Thus the bottles themselves form the spokes of the wheel. Novel “brewery” wheel used in corking bottles of unfermented fruit juice in Thuringia, Germany. APR

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Apri, 1930 POPULAR SCIENCE MONTHLY An officer of the New York emergency squad demonstrates to students the loading of tear gas bombs, the latest chemical weapon employed against criminals. These particular bombs were shipped to the State Prison at Auburn, N. Y., by airplane during the recent convict outbreak. A College tor Police A scene at the new Police College established by the City of New York for scientific training of officers of the law—‘‘rookies” receiving instruction in scaling walls, with the aid of ropes, to save life at fires. a oe The morning line-up of criminals in New York police headquarters. As they stand on the platform, blinding lights above their heads prevent their seeinz detectives examining them. Stanley Gorman, ballistic expert of the Police College, at work in his laboratory. Here bullets, examined under the microscope, are identified by the “fingerprint” marks which the weapons that fired them made. The photograph at the right shows future police officers receiving in- struction in the handling and shoot- ing of service pistols on the range of New York City’s Police College. PROGRESS AND DISCOVERY

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mee ated § rr tietaS as School for Rescue Squads in Abandoned Mine A nEw kind of life guard, which instead of saving men from drowning will learn how to rescue them from being buried alive, is now undergoing training in the coal mining district of Upper Silesia, on the German-Polish frontier. Here a mine long deserted is being uti- lized for the experiments in life-saving. Young mountaineers, whose occupations may carry them into hazardous under- ground passageways, are instructed in the working of the oxygen pulmotor, in the use of gas masks, and in the proper pro- cedure for getting a man out of the sub- terranean tomb in which he may be buried {alive or have {his exit cut off by landslide or other accident. Pilot Launches Airplane from Speeding Auto TAKING off from the roof of an auto- mobile speeding at fifty miles an hour was the novel feat performed recently at Old Orchard, Me., by a nervy airplane pilot. The stunt demonstrated that this new way of catapulting an airplane into the air is at least feasible, if not altogether soothing to the nerves of the average passenger who is not thrill hungry. Some months ago a similar attempt to launch an airplane from the roof of a fast train failed, the airplane being wrecked in the take-off. In the Maine attempt the machine was perched on a frame lashed to the top of the car and a device, operated by the pilot, released it when the car had at- ey This oxygen apparatus, being described to the class, is meant to save buried miners. Left: tim, are ready to put him on a stretcher. POPULAR SCIENCE MONTHLY eee oes The rescuers, after reviving a vic- was the pilot’s discovery that he could steer the automobile by swinging the rudder of the airplane. Is There a Limit to the Size of Hailstones? HAILSTONES remain a “size” puzzle even for scientists. The difficulty lies in verifying the statements of those who claim to have seen enormous stones fall. The most convincing record is that of a stone falling July 6, 1928, at Potter, Nebraska. This stone, it is said, measured seventeen inches around. Some of the stones falling at that time were described by eye witnesses as being “‘as large as grapefruit.” On August 1, 1929, large hailstones fell near Hartford, Conn., and did $1,250,000 damage to the tobacco crop. These stones were larger than hen’s eggs, according to reports and photo- graphs taken at the time. In 1914 two missionaries claimed to The hen’s egg, in the right hand, is dwarfed by these extra large Connecticut hailstones. tained sufficient speed. A curious incident APRIL, 1930 Equipped with gas masks and armed with pickaxes, the rescue squad will face mine gases. have seen ten-pound stones fall in China. In 1925 a German cigar maker of Heid- graben, near Hamburg, asserted that a four - and - one - half. pounder crashed through the tiled roof of his house. A century ago houses were said to have been crushed under “blocks of ice” in a storm that swept through the town of Carloza, Spain, on June 15, 1829. Studies Eskimo and Indian to Trace Kinship SOME anatomical facts which have late- ly been gathered in Alaska by Dr. Ales Hrdlicka, of the United States National Museum, may throw new light on the prob- lem of the relation of the Eskimo to the Indian. Dr. Hrdlicka recently reported to the National Academy of Sciences that he had measured 200 full-blood Indians and Eskimos, from head to foot. The results show, according to Dr. Hrdlicka, “that there is a growing warmth for the hope that before long: it may be possible to say something definite about the origin of the Eskimo and his relation to the Indian.” The expedition also did much to clarify ideas with reference to the ancient migra- tion route of the first people on this con- tinent. That the Eskimo m+y have wan- dered from the coasts of Siberia at a time when there were land linkages between Asia and North America has long been a favorite theory to which support is given by the wide span of the Eskimo’s habita- tion. There are seven groups of Eskimo scattered over the 5,000 miles of territory that lie betweén East Greenland and Asia. What mysterious links bind these widely separated tribes into a chain may soon be discovered in further investiga- tions by Dr. Hrdlicka.

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ApRIL, 1930 Priest Explores Alaskan Volcano wild region of Alaska where smoke and steam curl from thousands of holes in a valley’s floor returned not long ago with photographs and scientific rec- ords of one of Nature’s curiosities—the ‘Valley of Ten Thousand Smokes.” The leader of the band, Father Bernard Hubbard, geologist of the University of Santa Clara, Calif., is known as “the Glacier Priest” for his previous success- ful conquest of the Taku Glacier in southern Alaska (P. S. M., July, 728, p. 49). His companions in the new expedi- tion were ‘“‘Red”’ Chisholm, former Santa Clara football star, and Frank Klatt and Charles Bartlett, students. Leaving Katmai Beach, on the Alaskan Peninsula, the party climbed Mt. Katmai, a slumbering volcano, and entered the million-acre valley beyond. i ar adventurers who penetrated a

Father Hubbard celebrates mass in the wilderness beside Katmai Beach at the start of the trip to the volcano. POPULAR SCIENCE MONTHLY

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. Preparing a cache of food for the return trip. It «was hauled to the top of a tree where it would be safe from marauding animals.

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Steam heat on a cold | day. Frank Klatt, | student explorer, warms his hands at one of the fumaroles. or steam jets spouting from the floor of the “Valley of Smokes.” Left: At their goal. - Father Hubbard (right) and “Red” Chisholm view the Valley of Smokes from the sum- mit of Novarupta, a 3,000-foot slumbering <i volcano, one of the »— six within the region. «

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POPULAR SCIENCE MONTHLY Chicago’s Planetarium Nearing Completion

The new planetarium under construction on a man-made island off Chicago’s lake front. THE world’s finest example of a planetarium, an astronomical theater on whose domed ceiling are projected the relative motions of the heavenly bodies, is nearing com- pletion on an. artificial island off Chicago’s lake front. Inside the building spectators will sit in circu- lar rows about a multiple projector which through 119 lenses will cast the images of stars and planets on a vaulted screen ninety feet in diameter. By altering the slides behind the multiple lens projectors, it will be possible to show 4,500 stars, each one revealed in its natural size, brilliance, and location in the heavens. ' Planetariums similar to the one in Chicago have been built in a dozen cities of Germany, and others are undergoing construction in Italy and Soviet Russia (P.S.M., Jan. ’29, p. 130). Water Pumped Uphill to Keep Dynamos Busy BECAUSE of the demand for electricity during the day, ordinary power stations have to install expensive dynamos that are not used to full capacity during the night. A German power plant near the town of Niederwartha has adopted an ingenious plan to keep its dynamos run- ning at full efficiency all the time. Dur- ing the night, when the demand for electricity is low, the surplus power is used to pump water up a hill into large storage reservoirs. In the daytime the water is allowed to run downhill again, running a water turbine and dynamo and furnishing additional electricity when the need for it is greatest.

Analyzes Third of a Drop One 1,500th of a fluid ounce of chem- ical, or about one third the volume of a drop of water from a medicine dropper, recently yielded its secrets to a chemist in a New York City demonstration. It

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Looking up into the domed roof—the “night sky”? on which images of stars will appear. was the first public exhibition of a new way of testing minute quantities of chemicals. Formerly much larger sam- ples were required for analysis. In the test Dr. Joseph Niederl, of New York University, broke a fine glass tube containing the minute quantity of liquid in a vessel containing mercury and heated it until the liquid became a gas. As the gas expanded it forced off an amount of mercury equal to its volume. By figuring the temperature at which the gas vapor- ized, and its volume, the molecular weight was determined. A similar method of microanalysis was used by Dr. Niederl recently to test a substance developed as a rubber sub- stitute by a New York laboratory. Predicting Thunderstorms By MATHEMATICAL wizardry a. new kind of chart known as a “tephigram”’ is said to predict thunderstorms from five to six hours in advance. It shows the amount of energy available in the atmos- phere for release in the form of a thunder- storm, as wind or otherwise. A balloon equipped with weather instruments is sent aloft and the temperature, pressure, and other conditions of the air at various heights found. These data are expressed in curves drawn on the ruled paper of the “tephigram,” from which the time of a probable thunderstorm is revealed. The method, announced by C. M. Alvord and APRIL, 1930 R. H. Smith, of the Massachusetts In- stitute of Technology, is expected to be useful to warn aviators of storms. Finds Protons Play Dual Roéle; Wins Prize A SCIENTIFIC “Bolshevik” won a $1,000 prize the other day for upsetting one more of the fundamental ideas of classical physics. Prof. A. J. Dempster, University of Chicago physicist, proved that a proton, the core of an atom, leads a dual existence as both a tangible particle and an intangible sort of wave motion. For the feat he received the annual award offered by the American Association for the Advancement of Science. His discovery now makes a pretty mess of the attractively simpie picture of the atom that nineteenth-century physi- cists had built up. It was thought that an atom, or smallest possible complete piece of a substance, was made of two perfectly tangible things, both charged with electricity. One, the core, or “proton,” was positively charged; the other, consisting of one or more electrons spinning around the core, was negatively charged—and that was that: But in 1927 two research physicists at the Bell Telephone Laboratories, C. J. Davisson and L. H. Germer, partly spoiled this picture when they found electrons not only were particles but that they also behaved like waves. To find whether protons, too, had a wavelike nature, Dr. Dempster used a device like that which, in other hands, first showed X-rays to be true waves. This was a crystal of a mineral known as calcite through which he shot a beam of protons, in this case electrified cores or nuclei of hydrogen atoms, in a vacuum. A photographic plate caught wave pat- terns formed by the grating of molecules in the crystal, proving the new theory. Vibratioris of the atom cores that pro- duced the waves were a million times faster than those of light waves. How protons and electrons can be waves and particles at the same time, Dr. Dempster says, is “perhaps the greatest problem now confronting physics.”

Prof. A. J. Dempster, science prize winner for discoveries about protons, in his laboratory.

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Aprit, 1930 POPULAR SCIENCE MONTHLY a % f ¥ Apt «3g Boring a Tunnel 9,000 Feet Up Completing a cogwheel railway up the Zug- spitz, highest peak in the German Alps, work- men are driving a tunnel into the mountain at a height of 9,000 feet. Each day they travel to their job by cableway. Above: The lofty tunnel entrance, looking from within. At right: A view of the entrance in the mountain wall. -Hunts Leprosy Cure. The only woman scientist from America who is now doing research work in the famous Pas- teur Institute, Paris, France, is Adele Cohen, of Newark, N. J. At-present she is‘searching for a serum for the cure of leprosy. 2 Through the Rocks. This view within the Zugspitz tunnel shows a crew of workmen biting in the wall of solid rock with a pneumatic power drill, Notice the horn at the waist of the man at the extreme right. He uses it for signaling to other crews. ‘“*Taken for a Ride.”” Two of the workmen starting the descent by aerial cable car from the mouth of the railway tunnel in the Zugspitz. The railway will go nearly to the 9,722-foot summit. Sun Baths for Miners. Men who work in the depths of an Idaho mine get their share of sunlight in this special solarium. The miners, stripped and wearing protective goggles, stand upon a moving platform which takes one minute to travel in front of a battery of ultra-violet lamps. PROGRESS AND DISCOVERY

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52 Ocean’s Fioor Is Classroom for Undersea Zoologists In A sea-bottom classroom, with shim- mering green water for atmosphere and divers’ helmets for windows, the pupils of the marine zoology class of the University of Miami go to their work. Making semi- weekly trips to the floor of the ocean, the students study the rich variety of sea flora and fauna, and occasionally bring choice specimens up with them. Giant starfish, sea polyps, coral beds, sponges, and innumerable other interesting sea animals are among the objects of study. The students are clad only in bathing suits, and are equipped with diving hel- mets that fit snugly over the head and rest on the shoulders. Air is fed to the submarine pupils by tubes leading to the helmets from the surface. The professor, down there with them, jots down notes and instructions by means of a slate and pencil. Bees’ Tongues May Yet Prove Acquired Traits Persist FRESH evidence of the inheritance of acquired characteristics in animals, one of the major unsolved problems in bi- ology, has been discovered by Dr. W. W. Alpatov, formerly of the Zoological Mu- seum of Moscow, Russia, and now con- nected with the Institute for Biological Research, Baltimore, Md. In the course of a microscopic survey of the measurements of insects, partic- ularly Russian and American bees, the zoologist set himself the unique task of measuring the length of their tongues, the implement used by the creatures in gathering honey. He found that in Russia the length of the bees’ tongues increases as one travels south, the longest- tongued bees known to entomology living in the Caucasus, the southeastern corner of European Russia. At the same time, his investigation showed that the red clover, in which that country abounds, carries its honey so deep down in its blossoms that most other.types of bees cannot reach it. The conclusion was that the Caucasian bees were forced to develop longer tongues to POPULAR SCIENCE MONTHLY “Put it on,” says Hazel Heinrich, left, ready for the helmet and study. Above: The students of deep-sea life come up for air at intervals. reach the honey, and handed the new feature down to their offspring, thus fur- nishing a striking example of environ- mental adaptation. The late Dr. A. E. Verrill, prominent Yale University zoologist, found in Hawaii a species of crayfish whose tails had become twisted in a direction op- posite to normal as a result of having had to adapt themselves to different rock formations, and whose offspring had inherited the new characteristic. Machine Measures Thought but Is No Mind Reader THoucuts, as well as actions, can speak louder than words, according to Dr. Milton Metfessel, of the University of Southern California, when they are hitched up to an ingenious device he has just invented. Those thinking processes which go on so silently within people’s heads are, he says, actually the expres- sion of powerful forces at work, nerve impulses flashing from one end of the brain to the other along complex net- works of nerve fibers. Scientists before Thought impulses, picked up by electrodes laid on the tongue, are reproduced as sound. APRIL, 1930 Dora Peterson proudly displays specimens gathered from far below the rolling waves. probably have dreamed of measuring the impulses which constitute familiar thoughts, but Dr. Metfessel claims he is the first to realize this dream. In order to “put the meter” on thoughts, he has an individual stand before an electric amplifier and places a pair of electrodes on the tongue. The electrodes, he asserts, capture the delicate electric fields set up by the nerve im- pulses from the brain and relay them to the amplifier, where they may be repro- duced as sound in a loudspeaker, or as light waves which may be photographed. Blue Aniline Dye Now Used in Fight on Cancer INJECTION of small quantities of an aniline dye known as isamine blue into the blood stream is a new procedure in cancer treatment developed by specialists of the Charité Hospital in Berlin. The dye is absorbed. by the cancer cells rather than by the cells of the body’s healthy tissues. Several advantages are claimed for the new technique. The sur- geon’s work may be facilitated by the blue color of the dyed cancer, indicating the margin between the diseased and normal tissues, and the dye may also show small cancer-affected areas likely to be overlooked. In radium treatment, the dye is believed to increase the tendency of cancer cells to absorb, and be destroyed by, radium rays.

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930 “ae cas 18 ar yn id 1e€ te 1- [Oo )- 1S PB OSB —" OF OW Oi gan ry Aprit, 1930 POPULAR SCIENCE MONTHLY 53 Along the Airways of the World Curtiss Lindbergh’s new plane. With 450 gallon gas capacity, it leads all pleasure craft in range. Helicopter Will Soon Get Try-Out—Army Plane with Full Load Reaches 30,000 Feet an airplane that can rise straight up, is nearing completion at Garden City, N. Y., at last definitely confirms a Ni that a new type of helicopter, report published in PopuLar SCIENCE - MONTHLY some time ago (Feb., ’28, p. 43) that the Curtiss airplane firm was building one. At that time officials of the Curtiss Aeroplane and Motor Company declined to comment upon this report, significant as the first venture of a prominent air- craft concern into helicopter design. Now, however, it is known that the odd craft will soon have its first try-out, and a few details of its construction have become known. Within the steel chassis are a 425- horsepower radial motor and seats for two passengers. Above the cabin four wings, somewhat resembling those of the “autogiro” or ‘‘windmill”’ plane (P. S. M., Nov. ’29, p. 43), re- volve. Unlike the last, however, they are power-driven, and their combined lifting force is expected to raise the craft bodily into the air without a pre- liminary run. One important advantage of a craft of the heli- copter type is the small space it requires for landing and tak- ing off, making it possible to use back yards and roofs for landing fields. ~ No helicopter as yet has reached the commercial stage, al- though several have made more or less successful flights. Recently a heli- copter designed by the Italian inventor, Vittorio Isaaco, was Marine Corps flyers at San: Diego, Calif., are trained by this device to trust their indicators, instead of their senses, for direction and: bal- ance. With his head in the box the student is whirled around and discovers himself differ- ing from the instruments, which are right. completed in England and delivered for tests to the Air Ministry. Like the new Curtiss machine, it resembled the “‘auto- giro” with its “windmill” planes, but has individual motors on the forward edge of each of the revolving wings. Plan Nine-Day Air Service from California to Japan NINE-DAY flights from California to Japan by airship are now planned by a western air transport company. It is a subsidiary of the Goodyear-Zeppelin Corporation, which is now building the first of two super-airships for the Navy. Three other air- ships of equal size, to be built when these are completed, will constitute the air fleet that will in- augurate the new air line to Japan by way of Honolulu and Manila. A dirigible hangar will be erected in California. At To- kio, Japan, there is already a hangar of adequate size. Moor- ing masts to be erected at other points probably will be collapsible, so as ‘not to be dangerous to other aircraft. Airships plying the new line are planned to carry 100 passen- gers apiece: The air- ship route is not ex- pected to replace, but will supplement, pres- ent transportation by steamships. This striking photo shows the British dirigible R-100, which has flown eighty miles an hour. Army Plane, with Military Load, Climbs 30,000 Feet THIRTY thousand feet above the earth, an Army pursuit plane recently set a new altitude record for a loaded plane of this type. Lieut. Norman H. Ives piloted the plane nearly six miles above Rockwell Field, Calif., carrying ‘‘full military load.” Meanwhile, Lieut. Apollo Soucek, Navy flyer and holder of the 39,140-foot American altitude record for all types of airplanes, announced a successful try-out ia 7 pang eee tektites Saaete® hot eB, es EEE. NEEL SEG Sea SneNesete

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ee apres ee nreenennnenn Ne any ae Fe CR me mere ne et em ee significant. stalled in it. It makes of a special oxygen “lung” or mask he has designed to recapture for America the world altitude mark. It worked satisfactorily in a flight to 37,000 feet, he reported. At the time this issue went to press, the world’s altitude mark which Soucek hoped to exceed was 41,795 feet, reached last summer by a German flyer, Willy Neunhofer. Winning the “icicle crown” is a feat of practical utility. Observations of air currents believed to exist at great heights point to the possibility of future air lines at these levels (P.S.M., Dec. ’2), p. 26). For military purposes planes with high “ceilings,” meaning that they are able to reach great heights, are especially desirable. In aerial combat theplaneable to fly thehighest has a decided advantage over its foes —a fact which makes the recent record of a loaded pursuit plane particularly British Dirigible Sets High Speed Record A woRLp’s speed record for air- ships is clairned by the newest British super-dirigible R-100. In a recent flight near Cardington Airport, | England, it attained a speed of eighty-one and one half miles an hour. This speed, reached without using all the engines, is expected to be bettered. Both the Los Angeles, at present America’s largest airship, and the German Graf Zeppelin have a speed of about seventy-eight miles an hour, although the German ship is said to have reached eighty miles an hour. New Land Near South Pole Claimed for Norway NEw territory has been discovered and claimed for Norway by Capt. H. Riiser- Larsen and Lieut. Luetzow Holm, who landed by airplane in a corner of the Antarctic continent hitherto unexplored. Flying from a Norwegian ship, they alighted on the ice between Coats Land and Enderby Land, left the plane, and went ashore to hoist the Norwegian flag in accordance with the established inter- This is really a glider, though it has an engine in- fifty miles an hour and re- cently flew from Los Angeles to San Diego, Calif. POPULAR SCIENCE MONTHLY In oval, the $100,000 prize-winning Curtiss Tanager, called the “safest plane.” Below: The Tanager clears 35-foot stand with 500-foot ground run. national custom for taking possession of new territory. The portion of Antarctica they reached is directly opposite the South Pole from Little America, the base of Rear Admiral Richard E. Byrd’s exploring party. The coast line coin- cides roughly with the Antarctic circle; it is about 1,700 miles from . the Pole. Enderby Quadrant, the sector of Antarctica which contains the newly-discovered land, extends from 0° to 90° east longitude. APRIL, 1930 3 Airplanes Raise Problems ‘ in Planning of Cities WHERE airports fit into cities is now one of the problems of “city planning.” How high buildings near airports should be, how airport and transit lines should interconnect, and how air traffic in- fluences city zoning are questions to be considered in a study recently undertaken by the school of city planning at Harvard University. City planning is not new. One of the first recorded examples is the town of Kahun, in Egypt, which was laid out some 3,000 years before the Christian era. Early Greek and Roman cities were planned along carefully engineered lines, and among more modern cities Bath, England; Edin- burgh, Scotland; and Paris, France, are con- spicuous in this respect. But just as railroads with their yards and terminals modified city planning— errors in their location costing millions of dollars —so the advent of the air- plane brings new problems which city planners are beginning to recognize. Planes May Bomb Fish AERIAL scouts may bomb herring from the air, if experiments planned on the north coast of Norway prove successful. Special bombs will stun the fish, and they will float. An observer in the plane can thus detect large numbers of herring. These giant wheels, designed at the Lakehurst Naval Air Station, will be used on the Navy’s dirigiblés when at anchor to keep the big ships from tearing the stern as they swing with the of wind. The.tires are 45 by 20 inches, with 20 to 30 pounds air pressure.

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930 Ow z. ” ild ild in- be en rd pM OB ApriL, 1930 POPULAR SCIENCE MONTHLY Are You Fit to Drive Your Car? Testing peripheral, or “side-view,” vision. As lights flash behind small holes at each end of black box, subject reports what he sees by touching signal keys before him. In this way an examiner can judge quickness and accuracy of sight. Oval: Test showing how eye fatigue and weak muscles may cause accidents. Above: To prove he can use two hands at once and on separate jobs, driver must keep “Cartesian diver” in each tube from touching bottom. Yes, If You Are Properly Trained, Says Psychologist, Following Remarkable Tests HE date is 1935, the scene a city traffic court. “You are charged,” says the judge, “with reckless driving and endangering the lives of others. Your car, out of control, skidded and went over the curb at the corner of Broad and Main Streets. What have you to say?” “Tt wasn’t my fault, Your Honor,” protests the luckless driver. ‘‘The street was wet. The man in front of me stopped suddenly. I had to jam on my brakes, and I skidded.” “Tt is evident from your statement,” the judge replies, ‘‘first, that you were traveling faster than was safe under road conditions; second, that you were too near the man in front of you; third, that you don’t know how to operate a brake on a rainy day. A fine will not improve your driving. Instead, I sentence you to instruction at the municipal training school for automobile drivers until you know how to drive on a rainy day.” Fantastic? Not according to Dr. Knight Dunlap, Johns Hop- kins University psychologist, who advocates teaching, instead of fining, erring motorists. He is in a position to know. As chair- man of its division of anthro- pology and psychology, he recent- ly organized and conducted for the National Research Council, at Ohio State University, a unique program of psychological tests for automobile operators— the first of their kind ever made. Novel mechanical devices dis- sected and classified, for hun- dreds of subjects, the many kinds of ability that safe driving requires. Automobiles in this country By ROBERT E.. MARTIN are killing more than 31,000 people yearly and injuring or maiming about thirty-five times as many. Experts are demanding to know why these accidents happen. Why do some drivers have “bad luck?”’ If some persons are constitutionally un- fitted to drive, how can they be singled out and barred from the road? Plainly, not all dccidents are the fault of the driver. Reliable estimates lay a tenth of all smash-ups to defective cars. This cause should be easy to remove. In its “speed-with-safety” plan published in the February issue, POPULAR SCIENCE MONTHLY urges the frequent inspection for mechanical defects of every car, whether two weeks or ten years old. Motor experts, commenting on this plan, stressed in particular the importance of In this unique test of an cuttagoble driver’s eye-and-hand codrdina- tion an electric peg must be plugged into a hole in a zigzagging disk. this point. In Pennsylvania, wrote Motor Vehicle Commissioner Benjamin C. Eynon, a recent compulsory inspection showed 3,000 cars either improperly equipped or unfit for safe driving. Unfit cars will now be denied registration—an effective way to clear the streets of derelicts. But can human failure be prevented? The issuance of licenses, and traffic laws themselves, are concerned with the man who drives. Dr. Dunlap has studied the behavior of the man at the wheel. His conclusions are startlingly unconven- tional. A man who cannot pass a simple intelligence test, he says, may make an excellent driver. Cripples, with only one arm or leg, may safely drive cars that are properly equipped. Simple, common- sense training in manipulating a car’s clutch, brake, and steering wheel is the chief Tequisite. In other words, the _— ability to shift gears properly, and not a “hair-trigger” men- tality, makes a good driver. The great need is for education and practice in driving. But can psychological tests be directly applied in ree og 2 drivers? Dunlap’s answer is ‘ ’ Driv- ing a car requires seth a "peculiar combination of thoughts and motions that it would be unfair to single out certain qualifica- tions—say the quickness of response to a given signal—and use them as a standard of com- petency. It is better, he con- cludes, to consider a person’s driving as a whole than to attempt to analyze it. To this end a “proving ground” is to be opened at Columbus, O., where experts will observe the mental and physical quirks of motorists

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i on ee cone ' ' ; i i ' Plate OPPS MARA eR Ew om Bs Sass en P 3 wi ei . i #4 hi iT F ay Dae ae rs ee ee - oe toe a boos “ RS SY ai ie Se ee : ce a ama as if a reck- 56 driving real’ automobiles in- stead of laboratory models. Instead of providing, then, a “measuring stick” for as- piring drivers, as some observ- ers had expected, Dr. Dun- lap’s first psychological tests have explained the way motor- ist’s mind and senses function, revealing little-known facts about driving. Deafness, for instance, is not such a grave menace in a driver as in the pedestrian, who, for his own safety, should imitate the deer hunter and wear a red coat to distinguish himself. Bad eyesight, of course, is a more serious handicap. Yet Dr. Dunlap believes this does not cause many accidents. A far greater menace is the man who can see but won’t take the trouble to look. Can a color-blind person be- come a safe driver? Or will he be confused by traffic signals? Dr. Dunlap declares all persons are color- blind—except when they look squarely at an object. To see how a green signal looks to a color-blind person, simply fix the eyes upon a point about fifteen degrees— one sixth of a right angle—to one side of the light. Since an autoist usually ob- serves a traffic signal out of the corner of his eye, because he has to watch pedes- trians and other motorists at the same time, signals are designed on the assump- tion that all motorists are color-blind. Fortunately, there are two colors which a color-blind person can distinguish as well as aman with normal vision—orange-red and blue-green. Signal engineers are adopting these colors. NGENIOUS apparatus disclosed these and other facts about motorists in Dr. Dunlap’s tests for the National Research Council, which were made under the immediate direction of Prof. A. P. Weiss, director of the psychological laboratory of the Ohio State University. In one test of eye, hand, and foot codrdination, subjects sat at the wheel of a dummy automobile with the steering gear, brake, and clutch of a car, and an electric seat that registered the “dri- ver’s” movements. Six feet in front, an illuminated chart represented a road. Along this imaginary highway the subject drove his car. One pointer on the chart showed the course of the test car. Another pointer represented an imaginary vehicle coming toward it. The driver was supposed to steer the test car so as to avoid an imagi- nary collision with the oncoming car. It was hard to dodge, for mechanism gyrated the ap- driver were at the wheel. If the subject properly applied his controls, an automatic device cut off the power and stopped the pointer. For this the sub- ject received a perfect score. One interesting fact this test revealed was that men are more active behind a steering wheel than women. A dummy traffic light stood POPULAR SCIENCE MONTHLY Judging distance. A pointer moves steadily, first across opening, then behind screen, when driver must stop it, at stated points, by pushing a button. beside the imaginary thoroughfare in some tests, and changing lights gave stop and start commands. Thus the best posi- tion of traffic lights for visibility was determined. Also, this test helped to show which drivers were prone to ‘‘jump” the red lights. A “noise barrage” was the means of testing a driver’s lack of “emotional stability” —in other words his tendency to fly off the handle or become confused by strange sights and noises. The subject sat in a padded chair, a pair of electrified handles in his hands. These carried a current far too mild to be felt, for the object was to detect the extremely deli- cate electric changes in the body itself. Suddenly, bells clanged. Lights flashed crazily. Buzzers whirred. A gun cracked, so close that the subject could smell the burning powder. Meanwhile a delicate galvanometer, an electric meter in the next room, measured the subject’s ability to keep calm. -Few but truck drivers survived this test. A motorist’s ability to judge motion and distance was measured by a pointer that moved across an opening between two screens and then disappeared behind them. It was traveling steadily. The subject was asked to stop it, by pressing a button, when he thought it had traveled a specified distance behind one of the With brake, clutch, and steering wheel, driver shows how he would prevent head-on collision. A pointer represents an oncoming car. APRIL, 1930 screens. A graduated scale on the pointer’s track measured how good a judge of motion the subject was. Other tests measured a sub- ject’s eye-and-hand coédrdina- tion, his ability to do two things at once, and his heart action. For the first, a subject tried to plug an electrified peg into a hole in a brass disk that zigzagged elusively in front of him. Then he tried to keep two “Cartesian divers,” little rubber floaters in separate tubes of water, from touching bottom by manipulating an air pump with each hand at the same time. Finally he ran five steps up and down a special stepladder, so that his heartbeats could be observed. The main value of such tests is that they provide basic in- formation about motorists that never before was available. How far they can be applied directly in judging any individual motorist’s quali- fications for a driver’s license is a ques- tion. That they should be interpreted with caution is emphasized by Dr. Dun- lap himself. Quickness of response, he points out as an example, is not always desirable in driving. The man who sets his brakes suddenly may endanger an- other driver behind him. Thus a simple psychologicai test to measure a man’s speed of action is not alone a sufficient index of his good driving. A more com- plicated test to measure his speed of correctly deciding what to do, instead of merely acting on snap judgment, is open to the criticism that a man may do one thing in the laboratory and another on the road. HE best kind of examination for drivers at present, Dr. Dunlap says, is simply a rigorous test for a driver's license such as many states now demand. At least such tests compel the driver to learn something of running a car and of . traffic laws. It would be a good thing for an inspector to flunk a few candidates occasionally, just to emphasize that-a man must practice thoroughly before he is competent to drive alone. The ideal driver, Dr. Dunlap declares, is the man who acts automatically without having to stop and think. So the task now before the experts is to develop, with these basic tests as a guide, some way of barring the unsafe driver from the road and giving its free use to all others. Few unsafe drivers are born that way, and the majority can be taught to drive safely, Dr. Dunlap con- tends. This training in the fundamentals of driving is the present need. _ A step in this direction is that of a Brooklyn, N. Y., asso- ciation of car owners, which recently set aside a $50,000 fund to teach safety measures to «drivers_and pedestrians. And many organizations throughout the country are recognizing the wisdom of preventing accidents before they occur.

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930 red ion ib- wo art ect eg lat ep tle tte ng an at an is its aw tt ed Me oe ee. Oe. ee . Apri, 1930 Harbors for Motor Boats Many towns face big problem in caring for thousands of small craft—Municipal docks, now in opera- tion, are paying re- turns on investment By GEORGE LEE DOWD, JR. is to be tried in Detroit. Individual “boat wells” of concrete, similar to stalls for automobiles in a garage, are part of a $249,000 structure planned for that city. Cruisers and runabouts speeding up the Detroit River from Lake Erie, or coming down from Lake St. Clair, will put up in these wells, which are leased by boat owners for the year. Already sim- ilar privately operated boat harbors offer shelter for water craft in that city. Thus one city solves a problem that A NEW way of parking motor boats POPULAR SCIENCE MONTHLY 57 This is a model design for a small boat basin. The T-head docks afford protection from the waves and supply parking space for hundreds of boats. Such harbors are being constructed by several cities. able. The experience of most of the big cities shows that it is a problem for the municipality itself. Imagine 32,000 motor boats crowded into one of the most densely populated areas in the world and a picture is ob- tained of the puzzle that confronts New York City, the center, by sheer weight of numbers, of any small boat discussion. Several yacht clubs house a few boats. The rest are docked as best they may be. A harbor built across the Hudson River at Englewood, N. J., by the Palisade yearly becomes more acute— where to dock motor boats. The United States, with its fine in- land waterways, lakes, and shel- tered ocean-routes, offers splen- did routes for motor boats but few places to keep them. In cities especially, where private boathouses are fewer, facilities are often woefully inadequate. Yacht clubs provide mooring for only a few craft, compared with the number that would be used if more harbors were avail- | HOW MOTOR BOAT DOCKS Above are shown, at left, an approved method of mooring small boats in tidewater, and, at % a ace RS peer tae 55 4a right, a dia- gram of the “boat well” harbor planned for Detroit. The bottom picture illustrates the confusion and congestion at a typical city yacht club landing, in most places the only refuge for small water craft. Interstate Park Commission, was im- mediately filled to capacity and now has a waiting list of one hundred boats. The National Association of Engine and Boat Manufacturers, which has made a survey of harbor facilities all over the country, estimates that if New York provided sufficient mooring space its motor boat population would jump at once to 100,000. Owners could easily commute to the city, as a few now do, and park the boats in slips during the day. ‘The craft would be easily accessible to city dwellers for evening, afternoon, and week-end cruising, in- stead of being anchored miles from the city. Already New York is awakening to this need. Money has been appro- priated by the city to build two small yacht basins in connection with an exten- sion and improvement of Riverside Park, a munic- ipal park fronting the Hud- son River. According to Park Commissioner Walter R. Herrick, the Park Department is ready to proceed immediately with their construction as soon as a railroad with tracks in the park area completes its announced project of covering them. EANWHILE the National Associa- tion of Engine and Boat Manufac- turers proposes a much more extensive plan—to line the water front from this park northward, for six miles, with a series of docks for small water craft. These would accommodate hundreds of boats through the use of ‘‘T-head”’ piers —so called because of their branching ends on the water side. They would be built on concrete or metal-covered piles which would allow a free flow of water beneath the docks, avoiding accumula- tion of silt and sand. The river front adjoining the docks would become a promenade. (Continued on page 150) pct abg ie i - ‘ -atee x . . sigpariniaet iortndnne oe ore ip: natrernanaeeande te 7 - i - ~ I . ’ - J x ge Se Sg ee ee . Sos rad ae Se Rg 1 — ar

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a PO A a a i a a ee eter reny a re , ee wise ; - 69 EE 58 POPULAR SCIENCE MONTHLY APRIL, 1930 I've Seen a Lot of Flying! Vi ne Bivoniatam aorta Veteran Pilot Recalls Dare-Devils and Their Flights and Tells of the Narrow Escapes When Airplanes First Flew TIS nearly twenty years since I climbed into my first cock- pit. While I have been travel- ing the skyways, flying fields have developed from bumpy cow pastures to concrete runways; airplanes from lumbering box kites to winged bullets; hangars from flimsy canvas tents to huge structures of concrete and steel. The other evening, I looked over an old scrapbook I began keeping in 1910. Yellowed clippings told of a cross-country flight of 106 miles “electrifying Europe’’; of Henry Farman landing after eight hours in the air amid “hysterical ap- plause.” Only twenty years have passed since those items were news. The daily press now calmly tells of Costes and Bellonte winging from Paris to Mongolia in a single hop; of the St. Louis Robin circling tirelessly for seventeen days; of eight mil- lion miles being covered by the planes of the American air mail in a single year. When Farman brought his biplane to America for an exhibition, a little more than twenty years ago, it had to be entered as a “theatrical effect.”” There was no head- ing on the duty list to cover it. Last year, our aircraft exports amounted to three and a half million dollars. In 1910, pilots were still classed as “madmen.” They wore their caps backward. And they learned to fly in planes that shouldn’t have flown. Students largely trained themselves. They “cut grass” a few times. Then they hopped off—for better or for worse. An idea of how fledglings were instructed can be obtained by read- ing between the lines of this news item, dated April, 1910: ‘‘Mourmelon, France. Van Der Born, the old Belgian profes- sional bicycle racer, has been a teacher at the Far- Blanche Scott, one of the first girl flyers, is shown here in an early Curtiss plane, ready to take off. Note the shoulder yoke for balancing the wings. A chain of aerial lighthouses stretching from coast to coast now guides the night flyer. Left: Curtiss Robin plane. Compare it with its ancestor below. By ASSEN JORDANOFF man school here for some time. Recently he taught four pupils in a single week.” A modern school takes six or eight weeks to teach a student to pilot a plane that almost flies itself. The marvel is that some of those early human birds are still alive. One who flew under a lucky star was the Frenchman Louis Paulhan. In 1909, Paulhan was earning ten dollars a week as a factory mechanic. In 1910, he made $100,000 fiying his Farman in cross- country races. He was small, with quick, birdlike movements. When excited he would rattle out words with the speed of a machine gun. Exactly opposite in appearance and temperament was Hubert Latham, pic- turesque pilot of the wide-winged Antoin- ette monoplanes. He was a tall, morose man of few words. Doctors told him he was dying of consumption. He turned to aviation to get the biggest possible thrill out of his remaining years. Latham took chances no other flyer dared to take. He didn’t care. He boasted of kicking fate in the shins. And he escaped uninjured in every crash.* When death overtook him, it was far from a flying field. Just be- fore the war, he was killed by a maddened water buffalo while on a hunting trip in the heart of Africa. He passed out, as he had wished, in a momient of adventure. In those early days, every plane had its own system of control.. The Antoinette had

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~~ OO OD VB mw HM se wrereyTalUWw lit Aprit, 1930 two vertical wheels, one on each side of the skifflike body. The right wheel op- erated the elevator. The left warped the wings. A foot bar governed the rudder. The Wright machine had two upright wooden levers. The right one warped the wings and steered to right or left. The other controlled the elevator. In my first plane, a Bleriot, I steered to the right or left with a foot bar on the cockpit floor and warped the wings and pointed the nose up or down with a small wheel, like that on a bobsled, located between my knees. My Farman was steered with a foot bar, and the elevator and ailerons were operated through a single lever at the right of the pilot’s seat. In the Voisin, a wheel took the place of this lever. Nowadays, two types of controls predominate. Both move the rudder with a foot bar. The “stick” control has a vertical bar located between the pilot’s knees. It operates the elevator and the ailerons. The “Dep” control, used on large ships, has a wheel at the top of the stick. This wheel is turned to move the ailerons and is pulled back or pushed ahead to point the plane up or down. Instead of “riding the ship through,” leaning with it as it banks and twists through the sky, as pilots now do, the early airmen leaned away from the lower wing unconsciously, as passengers do on their first flight. This habit produced the Curtiss shoulder yoke and Santos- Dumont’s curious shirt. GANTOS-DUMONT, a tiny hundred- pound Brazilian, made the first heav- ier-than-air flight in Europe. In 1906, he hopped across a field on the outskirts of Paris in a cellular, box-kite biplane. Later, he built a butterflylike.midget machine of bamboo and silk. Its wing spread was only sixteen feet. He balanced the tricky little craft by attaching the warping wires to a metal piece sewed to the back of his shirt. When a gust tipped the craft, he unconsciously leaned away from the lower wing and the action righted the machine. The Curtiss shoulder yoke was a similar arrangement. A metal bracket fitted around the flyer’s shoulders and operated the ailerons. It was used on these planes until the war. Many of the early machines, like the Farman and the Hanriot planes, had skidlike sleigh runners that ex- tended from under the nose halfway back to the tail. Three times I have POPULAR SCIENCE MONTHLY or é In 1910, the Antoinette and Hanriot, dragon-fly types of planes, shown in the photograph above, were filling the world with amazement while reckless aeronauts drove them in gruelling races across France. seen the wheels fall completely off such ships. Each time, the pilot cut the switch and sat down on the grass, sliding to a stop without damage. Once the landing gear, skids and all, fell off a Farman I was flying. I had started off with a tank full of bad gas, a familiar occurrence in those days. The mechanics held the tail until the engine was racing. I raised my hand. They let go and the plane dashed off in a cloud of At the top: Wilbur Wright’s first idea of an amphibian is shown. Note the canoe slung beneath the wings. In circle: A close-up of a Farman, showing the ladder that stuck out in front of the wings, on which the flyer sat. Below: Santos-Dumont’s box-kite plane which he used in the first flight in Europe. dust. The motor wasn’t delivering full power. The ship reached bumpy ground at the end of the runway before it got up flying speed. Just as it lifted clear, the landing gear went to pieces and dropped off. Fortunately, the plane was a slow- moving bus and had lots of wing spread. When I cut the switch it pancaked into the weeds and I wasn’t scratched. A few weeks ago, I remembered those flimsy landing gears when I came down for the roughest land- ing I ever made. I was ferrying a big twin- motored ship to Phil- adelphia. It was zero weather. Over broken country in New Jersey, ice formed in one of the carburetors. The mo- tor cut out. I swung into the wind in a one- gun turn and decided to land. The _ best field below was covered with dried weeds. I set the big ship down carefully with the nose high, as I couldn’t see what lay under the weeds. Crash! Bumpedy-bump-bump! I thought the wings would shake off. I had landed crosswise to the frozen ridges of a potato patch. A landing like that would have made kindling of the old Farman, Voisin, and Bleriot ships I used to fly. Yet, when mechanics made a careful examination, they found that modern plane not even strained. The first multi-motored plane I flew was a Farman “Goliath.” It had a pair of 300-horsepower Clerget engines. Pilot- ing it was a constant strain. If one motor cut out unexpectedly, the other would pull the ship into a spin unless the pilot acted on the jump. In a modern twin- engine craft, we make one-gun turns regularly, throttling down one engine and letting the other pull the plane around. And motors don’t cut out now as they did a dozen years ago. Then, more hours were spent on the ground tinkering with a motor than in the air flying with it. In pusher planes, the engines were placed just back of the pilot’s seat. If he crashed or nosed over, the mass of steel crushed him or boiling water from the radiator scalded him. This position of the engine in early biplanes accounted for many fatalities. Because they (Continued on page 146)

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Somme <i ae oe

Here is your chance to test your ability to express yourself correctly. On the choice of the right word may depend your future YOUNG man once wrote a letter of fifteen lines to a famous col- lege president asking him to help him get a job. That letter is today hang- ing in a fine frame above this president’s desk, and he has often said it was the finest piece of business English he hzd ever seen. The boy got the job. Your own future may depend on your ability to express yourself in good, clear language. And language is something you can learn; it is not a gift from heaven. Recently experiments on language learn- ing have been made among the prisoners in Sing Sing, many of them fifty to sixty years old with little or no schooling. Their rapid improvement in the use of language in both writing and speaking is amazing. Here is a test by which you can tell your. own language ability. It was de- vised by Dr. Richard D. Allen, assistant superintendent of the Providence, Rhode Island, schools. You are allowed just fifteen minutes to go through the test, which consists of thirty-six sentences, each containing alternatives in the choice of words, the wrong word to be crossed out in every instance. The correct an- swers will be found on page 144. Do not look at the answers until you have completed the test. Then you can score yourself by reference to the following: Less than 12 failures, grade A Between 13 and 17 failures, grade B Between 18 and 23 failures, grade C More than 23 failures, grade D Dr. Allen finds that the average person who is still in school gets about the fol- lowing number of sentences correct: Age No. Correct Age No. Correct 12 15 16 24 13 17 17 26 14 20 18 27 15 22 19 orover 31 Dr. Allen says that it often takes six months of schooling for the pupil to raise his score more than one or two sentences. The average eighth grade child gets about 17 correct; first year high school (ninth grade), 20; second year, 23; third year, 25; fourth year, 27; average college fresh- man, 29; average sophomore 32. He finds that ‘the: average American adult probably is not far from the eighth to ninth grade pupil in language usage. If you do better than this, you are probably above the average grown person in America, in mmar and language. You can greatly improve your score by reading and study. POPULAR SCIENCE MONTHLY ‘Do You Know Your English? i) —_—

APRIL, 1930 You are to correct the errors in the following sentences by crossing out the incorrect words. Allow fifteen minutes. Do not guess. Leave those you cannot do. The correct answers appear on page 144. . Henry has a. three apples and has ten “ brother one. Take - Bring me es small picture first and then — the large ones to Miss Blank. 3. It must a been very late when the boys —_— their work. on oe 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 31. 32. 33. 34. To two too . Two men were tO many tW° do the work. Too too to Four pies were to be divided — six boys, and as a result, a fight began among between two friends. Did you see ow and we in sailor suits? Every pupil =. to remember that this is oo school. The cold wind blew “ety and made the children’s cheeks look very wat om the light near your mother and in the book on the table. Everybody A able to do — work by Somepee He FB know who’s to Bl the present. You oun never one to complain that the news we received ‘= unfavorable. It’s time the dog had jes bath. The jury — returned ,...% verdict. Play the game ame I do, and you shall not fail like John. Did you ask if you pe go to the library - get a book for school work? ‘ ° is - its The pair of scissors are not in their place. . . have . its ° The graduating class pag just held gheir exercises. As the men ben A in wait for the enemy, they saw three battleships ae at an- chor in the harbor. He put his hands RX his pockets and said, “I am the ‘caller of the two.” John and his father =. decided that twelve dollars = too much to pay. Please — the papers on my desk remain as they are, for I have ite them in a certain order. . Mary une go with us, 4 she not? Each of the boys fame oud to have 7 work accepted. sternly . Did the teacher look very ‘stern at the pupils when they did so Jaoay in the examination? I like to help those —. I love and at. I know love me. 27. Measles a many children among oy victims. I believe Pl and er to be honest. Mary’s money was stolen ae. her, which was different pon losing it. Neither John nor Frank — failing on the examinations because history and geography = easy for them. pre at any child can learn to swim os and almost all young people enjoy this sport. Everyone was oe except oe and | me. I knew the visitors to be b .4 as we invited all be ig we thought would come. As there is no doubt of — being invited, you oneal rely on _— being there also. . Every book and paper = found in =— place. 36. hall — “ ° I ‘will see that John studies in the future, and I believe that he —_ regret this later.

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930 in Aprit, 1930 POPULAR SCIENCE MONTHLY 61 POPULAR SCIENCE SCRAPBOOK News, pictures, and brief bits about unusual people, places, and things from all parts of the world are shown on this and the following pages WINGED BOAT TO TRY TO CROSS OCEAN A SPEED boat that may challenge aircraft in the offering of swift and safe ocean trans- portation has been in process of construction at Quincy, Mass. It is announced that the odd craft will attempt a_ trans- atlantic voyage when completed. Powerful struts, banked against each side of. the hull, support a monoplane wing structure forty- eight feet wide. Two twelve- cylinder Liberty motors will propel the extraordinary ship at a speed of ninety miles an hour. The motors are to be placed along the top of the wing struc- ture, as on a giant Dornier flying boat. Forty feet long, with a wide hull allowing room for a spacious cabin, the boat will be able to carry thirty-two passengers. Its Hull of new speed boat ready for airplane wings and motors. gasoline capacity is 1,100 gallons. It is said that the craft’s movement will be like that of a flying fish, skimming from wave to wave. The aim of the new ocean speed boat iS to achieve the highest speed possible without incurring needless danger. If the venture is a success, large ships of the same general design might be constructed for passenger service across the Atlantic. For the present, a speedy mail service might be started. LONGEST AIR MAIL TRIP ARRIVAL in New York of the first air mail from Montevideo, Uruguay, South America, marked the completion of the longest air mail haul in aviation history. The 8,000-mile journey was from Monte- ee tae, Me RS % ue » ae video across the lofty peaks of the Andes Mountains to Santiago, Chile, thence up the west coast of South America, and to New York via Panama, Canal Zone, and Miami, Florida. NEW ITALIAN STEAMER MAY BEAT BREMEN BEATING the record of the Bremen, fastest ocean liner afloat, is the aim of a steamer now being built at a shipyard in Genoa, Italy. The new vessel, with a 47,000-ton displacement, is expected to run from Cadiz, on the west coast of Spain, to New York, 3,151 nautical miles, in four and a half days. On her record trip last summer, the Bremen traveled 3,100 nautical miles in four days, seven- teen hours, and forty-two minutes. Mounting a four-blade propeller on one of the two Liberty motors carried in the wings of the craft. BIRDS FORETELL SPRING BETTER THAN MEN : N As THOUGH they possessed some mysterious knowledge of the exact date of spring’s arrival in their northern home, migra- tory birds return to England from southern Europe and north- ern Africa just in time for the opening of the flowers. This curious fact has been observed by British workers in phenology, the science which each year re- cords the first and last dates for such operations of Nature as the falling of leaves in autumn, the first appearance of buds on plants, the first opening of flow- ers, and the semiannual depar- ture and return of birds of passage. The time when these phenom- ena occur varies slightly from year to year, probably on ac- count of differences in weather conditions. Observers at 467 English phenological stations, according to a report recently published by the Royal Mete- orological Society, have noted that whether the spring be early or late, the return of the birds from their winter homes coin- cides almost exactly with the opening of the flowers. Phenol- ogists believe that some hitherto undiscovered world-wide weather influ- ence acts as the “signal” for both the beginning of plant growth and migratory bird travel. ANCIENT SWAMP VILLAGE FOUND IN SWEDEN ANCIENT ruins, perhaps dating back to the Stone Age, have been uncovered in the swamps of Dag in Ostergothland, a central province of Sweden, which have been the scene of interesting excavations since 1919. The diggings were supervised by Dr. Otto Froedin, Stockholm archeol- ogist, and financed by the Swedish gov- ernment. A primitive swamp village has been brought to light, built on the marshes and surrounded by a stockade like an early American Indian village. The choice of so undesirable a site for a latge settlement seems strange, although, Dr. Froedin says, it was doubtless an ideal refuge from invasion. Flat stones laid throughout a large part of the settlement give evidence of exten- sive road construction. The houses were floored with heavy logs. Fireplaces cov- ered with ash, coal, and charred bones have been unearthed, as well as imple- ments of stone and horn.

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| ; | PP Tar ae Pom paras seer wanes {emeess ape fet er eee aa: 5 i . ee ne a Ae te ng ee POPULAR SCIENCE MONTHLY “NIGHTMARE”? ANIMAL DOTES ON EGGS This staring-eyed creature, the Madagascar aye-aye, is a distant cousin of the monkeys. The nut and egg show how it digs in with its finger to get its food. Wirth claws that call up childhood memories of witches’ talons; a ghoulish, sharp-pointed face surmounted by naked ears; large, staring eyes; and an unkempt, bushy tail, the aye-aye of Madagascar, a cousin of the flying lemur, has well earned its appellation of a living night- mare. The creature is about the size of a largé domestic cat. In the wilds of Madagascar, where C. S. Webb captured the pair he recently gave to the London Zoological Gardens, the aye-aye has to fend for itself, and it finds the pursuit of food an excellent oc- cupation. For this it is endowed with an extra long ‘‘middle finger” which it can thrust almost anywhere and move with lightning speed. Though the aye-aye likes to scoop honey from the combs of wild bees or gather grubs from bits of rotting timber, stolen eggs are its long suit. First it breaks a hole in the shell, then up and down goes the long claw, scooping out the meat of the egg and carrying it to the aye-aye’s mouth, with such precision, it is said, that no morsel ever falls to the ground. CHALK LINE FOR AUTOS AUTOMOBILE wheels will run in grooves in a unique roadway under construction across Queensborough Bridge, in New York City. The grooves, about two inches deep, are a new experiment in keeping cars in line. The entire roadway is twenty-six feet wide and accommodates three lanes of traffic, with grooves in each. Low side walls, about twelve inches high, will also separate the traffic lanes. The new highway becomes possible with the removal of rapid transit rails from the upper deck of the bridge. The grooved roadway will be 10,300 feet long, one of New York’s longest traffic arteries with- out grade crossings. The bridge with its approaches is over a mile long. More than 87,000 autos cross it in a day. WOMEN STILL BEAT MEN IN TESTS OF EMOTION THE ancient doctrine that woman is ruled by her passions and man by his reason seems to find fresh support in a new study of sex differences conducted at Stanford University in California by Prof. Lewis M. Terman and Dr. Catherine C. Miles. The evidence, based upon the statements of students themselves in an- swer to questions, indicated that women strike more intensely than men on the whole scale of emotions—anger, pity, fear, or disgust. The most marked distinction be- tween sexes was exhibited in the realm of disgust. Here only one man out of four showed anything like the aversion which the average woman showed in response to certain situations. Contrarily, the emotions of pity and fear were about equally manifested by both males and females. However, the most satisfactory in- dication of the tests as a whole, the ex- perimenters reported, was that older, more intelligent, and better educated individuals, irregardless of their sex, show a verging away from extreme emotional conditions of any sort. $20,000,000,000 IN GOLD MINED IN 400 YEARS A “BULLION CUBE” only 38.5 feet high, wide, and long would result if all the gold mined in the world since the days of Columbus were cast into one solid block. While this amount seems surprisingly small when depicted in this manner, four miles of street thirty feet wide could be paved with a one-inch thickness of the precious metal, it has been estimated. The hypothetical block of gold would weigh about 65,000,000 pounds, or more APRIL, 1930 than a billion ounces, and its value, at the current price of twenty dollars an ounce, would be somewhere in the neighborhood of twenty billion dollars. According to the United States Bureau of Mines, more than half of the gold in existence today has been mined since 1900. This is due partly to the fact that the rich gold mines near the Klondike River in Yukon territory were discovered just before the turn of the century and have been developed since that time. Their yield in 1926 alone was estimated to be more than $879,000. PLANT POSES AS SNAKE TO TRAP LIVE FOOD Nort with the glitter of its eyes, for it has none, but by the glistening of its . highly colored leaves, the darlingtonia, a unique carnivorous pitcher plant native to California, imitates the hooded cobra, which it somewhat resembles, in luring - its unsuspecting victims to their doom in- side its “‘stomach.” The plant, named after William Dar- lington, American botanist, consists of a cluster of hollow leaves, each shaped like a spiraled candlestick and rising straight up to a height of one or two feet. At the summit, where it is broadest, the leaf arches over to form a cobralike hood from which hangs a blade like the tail of a goldfish, protecting the mouth of the pitcher. The insects that are attracted by the bright colors of the leaf find their way into this mouth and are guided to the bottom of the pitcher by downward-point- ing hairs on its sides. Once down, there is no escape, for the hairs that formerly acted as guides have now turned jailers and bar the exit. In their unique prison the victims form a putrefy- ing mess, and the products of their decomposition are said to be ab- sorbed by the leaf of the plant as food. Having no‘ pride, the darlingtonia imitates the cobra in getting the insects which it eats. APR

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Aprit, 1930 POPULAR SCIENCE MONTHLY This Arm Won’t Burn. Machines that seem alive reach into the furnace, drag out the ingots of steel, and pass them to the rolling mill. Danger Lurks in Liquid Steel. Enormous ladles of white-hot metal, which if released would spread in a devastating flood, are raised by great cranes and from them ingot molds are filled. At the right: Sixty-three tons of bubbling steel are surging into the ladle. This tapping of a furnace is one of the most thrill- ing moments in the whole process of the manufacture of steel. Accidentally Lifts Engine. A crane in the Pennsylvania Not Much of a Rocket. _It doesn’t look like a real engine, does it? yards, Chicago, grabbed a passing engine by mistake and wrecked it. But it is the great-granddaddy of all locomotives. It is an exact reproduc- tion of the Rocket built by Stephenson in 1829. It is now in the Ford The entire train was derailed and the engineer was in jured. This gives a slight idea of the enormous power exerted by a big steel crane. Museum, Detroit. The original is in the Science Museum in London. POPULAR SCIENCE SCRAPBOOK at + tim enn II ie ala

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Pega mye — eens : The model steam locomotive haul- ing a train. Electricity is its fuel At right: Completing the engine. ln testing various methods of generating steam in the boiler of a model locomotive which he com- pleted recently, E. B. Stack, of Monroe, N. C., found that elec- tricity would serve to produce the necessary heat. Instead of employ- ing an alcohol burner, or burning coal under forced draft, two methods long and suc- cessfully used by other model makers, Stack fitted three 600-watt electric heat- ing units directly in the boiler in contact with the water. Cleanliness and freedom from fire risk are the principal advantages of this novel steam-generating system. HIGHEST BRIDGE TO SPAN THE ROYAL GORGE More than twice as high as any other bridge, the loftiest in the world is soon to be under construction across the Royal Gorge of the Arkansas River, near Canon City, Colo. If a stone were to be thrown from this structure it would travel more than a fifth of a mile before it struck the river, since its greatest height will be 1,053 feet. At present the world’s highest bridge is the one at Lee’s Ferry, in the Grand Canyon, 464 feet high. WIRELESS PLAN PROPOSED NEARLY 60 YEARS AGO Rapz10, like many other inventions, had several fathers. It was not the practical triumph of Marconi alone that started it on its eagle flight, but the discovery of the electromagnetic law by Maxwell, the birth of Hertzian waves, and the dreams of cbscure scientists grasping at straws of the ultimate truth. Among the latter was an idea embodied in a remarkable “wire- less” bill proposed to Congress in 1872, twenty-five years before the first success- ful experiments of Marconi. This bill, now buried in the dusty files of the Con- gressional Record, proposed the formation of the Loomis Aerial Telegraph Company to exploit the theories of Dr. Mahlon Loomis, of Washington, D. C., whose principles bore a startling resemblance to those upon which modern radio is based. “The theory,” read the Loomis manu- script, “assumes that the earth itself, the POPULAR SCIENCE MONTHLY ELECTRICITY RUNS MODEL STEAM LOCOMOTIVE atmosphere surrounding it, and the infi- nite depths of space encompassing this aerial world contain a succession of con- centric circles or planes of electricity. Those nearest the earth are perpetually disturbed by oceanic currents... etc. Above these, pierced by the tops of lof- tiest mountains . . . are vast surrounding seas of undisturbed electricity, which may be affected by any interpenetrating gal- vanic force from beneath, causing elec- trical vibrations or waves to pass from that point within such electric plane around the world... ” Thus did one dreamer anticipate the great day of the loudspeaker. WOMEN DRIVERS EXPECT TOO MUCH COURTESY? Auto driving and chivalry should have little in common, according to Dr. E. B. Turner, of the Medico-Legal Society of London, who blames the feminine sense of traditional courtesy for the accidents which most women incur on the streets and highways. When a woman driver ar- rives at a corner, she usually unconscious- ly looks for the same sort of treatment from a man who may be crossing there that she would expect at a dance or a con- cert. This is a fatal mistake, says Doctor Turner. Too many women drivers expect every one and everything to get out of their way. Otherwise, the doctor states, women drivers are among the best on the roads, making good use of their inherited quickness of perception and movement in avoiding difficulties. FIND TOMB OF ANCIENT SCYTHIAN CHIEFTAIN NEAR the Mongolian border of Siberia, Professor S. I. Rudenko, of Leningrad, has uncovered the massive log tomb of an ancient Scythian chieftain, believed bur- ied more than twenty centuries. It re- veals that these warlike horsemen of the APRIL, 1930 steppes, known to have defeated the picked troops of the great Persian king, Darius, in 512 B. c., had attained a high state of culture in Central Asia before they migrated to the westward and came in contact with Greek and Persian civilj- zations. The main room of the burial chamber had been looted, but the Russian scientist recovered bits of woven goods and a num- ber of household objects. In another com. partment were ten carcasses of the favorite horses of the chieftain, slain, evidently, to carry their master into the next world. They had been permanently preserved in the frozen soil. Two of the mounts wore elaborate headmasks of skin and felt, ornamented with gold. Saddies and bridles, although of crude construction, were richly dec- orated with gold and carvings. The fig- ures represented reindeer, carnivorous animals, birds, and human beings. The ten horses are being transported to Leningrad for examination by laboratory experts. The tomb site is not far from the Gobi Desert, where the 1928 American Museum of Natural History Expedition, headed by Roy Chapman Andrews, uncovered re- mains of prehistoric “dune dwellers.” COLLECTING RARE WOODS HIS HOBBY AT 75 AT seventy-five a man is just young enough to take up a new hobby, judging from the experience of George F. Dyar, of Waltham, Mass., who has assembled - what is said to be one of the most com- plete collections of woods and products from the trees of the world. In his home, Dyar claims to have more than 6,000 specimens, representing some 3,300 trees from all parts of the world, and including rare trees that are almost extinct. The collector took up his hobby at the age of seventy-five when a long and almost fatal illness left him an invalid. Just as remarkable as the extent of the collection is the fact that Dyar’s health has so improved because of his absorbing interest in his hobby that doctors who despaired of his life five years ago now see no reason why he should not reach 100. George F. Dyar, 75-year-old collector of woods, with a few of his more than 6,000 specimens. AP! i

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DS oung iging yar, bled com- lucts ome, 000 trees ding y at and alid. the salth bing who v see 100. Aprit, 1930 POPULAR SCIENCE MONTHLY 65 Aqua-Skiing Adds Thrills to Sea Sport Here’s a raging inferno formed of fifty gallons of burning gasoline, and through this sea of flame, a daring nine-year-old boy dashes on his swift flying aquaplanes. Aqua-skis are as evil-minded as bronchos and in a cloud of foam each tries to follow in its own course, towed by a rushing boat. Great skill is needed to keep the feet traveling in the same di- rection and avoiding a spill. Will he hit the target? Whirling along on an aquaplane, the archer tries for a bull’s-eye— and sometimes he gets it. But hit or miss, it is fun to try and is a real test of archery. Aquaplane jousting on the wide-open sea is sure to mean a sudden bath for some- body, but the thrill fans are eager to prove their skill and duck their enemy. With a ski that is a small aquaplane on each foot, dare-devils face the sea and tempt a swift submergence in efforts to do stunts. Here the rider has just hurled Sometimes the aqua-ski jump fails to come off, though one of himself into the air in the approved ski-jumping manner. His trouble comes the skis does. In that event the water bug goes under the when he hits the water. Then it’s “ride her, boy,” or take a deep dive. waves and comes up “‘all wet.” But he claims it’s great sport. POPULAR SCIENCE SCRAPBOOK

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SA EIT EF Nt NOE EIR NOT SAPNA Bis Ot OS : i nme meee > ed Sos ee Ce tet ee ee Ng ae a er ed 66 TOWERS PEEK THROUGH SEA OF FOG POPULAR SCIENCE MONTHLY Gotham’s skyscrapers piercing fog. A cLzaR day, with brilliant sunshine gilding dome and spire, is not always es- sential to bring out the high points of a great city’s skyline. A day of fog and mist may sometimes do the trick even better. This was demonstrated recently by an aerial photographer who took this ran- In Grand Central zone at left the Chrysler Building rises highest; Times Square is in foreground; in the distance is the downtown financial section. dom shot of New York City, blanketed in thick fog. The unusual success of his picture, revealing the tremendous mass effects of Manhattan’s labyrinth of tower- ing buildings, shows how a snapshot may frequently produce striking results unlooked for in this type of photo. ROMAN GODS FOUND IN OLD GERMAN WALL NEw and unexpected treasure turned up by the spades of archeologists is the discovery of a ruined foundation wall made entirely of sculptured Roman stones near the Rhine country town of Alzey in Germany. Dr. Friedrich Behn, cura- tor of monuments at Mainz, tells the story of the remarkable wall in a recent edi- tion of a German scientific periodical. The explorers, on the track of the remains of an early church, came upon the crumbled ruins of a building far older than the one they sought, a curious structure about sixteen yards square, of which littie remained but the founda- tions themselves. These were com- posed largely of the sculptured frag- ments of ancient pagan shrines and tem- ples, including nine altars, twenty-five sections of pillars, four inscribed stones, six broken statues and reliefs, and six blocks with images of gods on all four sides. The presence of so much valuable stonework thrown into the bulwarks of a building in such haphazard fashion sug- gests that the builders were hostile to the old Roman gods, and demonstrated their contempt for them in this way. GOVERNMENT COMES TO ANTELOPE’S RESCUE THE antelope, diminishing rapidly in the West up to a few years ago, is now coming back. This graceful and fleet- footed animal once roamed the American plains in herds numbering a million, but a census of a decade or so ago dis- closed less than 5,000 of them left. Pio- neers had tracked them down, -but with the advent of the automobile, more relentless hunters had pursued them; and in late years even airplanes had joined the search to kill. But the Gov- ernment took up the little prong-horned animal’s defense. Efforts were made to “plant” the antelope in likely ranges whence they had vanished, as on the floor of the Grand Canyon, and hay was provided for them when the snow lay deep. The results were encouraging. In 1927 there were about 7,000 accounted for; in 1928 the estimate was 7,700; in 1929 it was 8,500. Other familiar North American ani- mals in need of rescue were included in the revival campaign. The bison, the elk of Yellowstone, the great moose—all are on the up grade of reproduction. Today probably ten times as many deer range the Northeast as a quarter of a century ago. -To restore the old abundance of wild life requires public support of the Government’s efforts. ONLY FOUR ANIMALS OUTLIVE MAN GENERALLY believed to reach the fabu- lous age of 500 years, the whale never lives beyond forty. The longest authen- tic record for the elephant, supposed to live to the century mark, is seventy years. The fact that these great animals do not outlive man has been established by Professor A. D. Peacock, of University College, Dundee, Scotland, who recently APRIL, 1930 completed an exhaustive study of the subject. He found that there are only four creatures whose ages regularly ex- ceed those of human beings. They are the giant tortoise, which reaches the ripe old age of 150 years and may live to 200; the German carp, whose life span is also a century and a half; the white-headed vulture, one specimen of which holds the 118-year record; and the eagle, which has known to pass its 104th birthday. Other centenarians among the birds are the parrot, the crow, the raven, and the eider duck of the Arctic regions. Here are the maximum ages attained by some domestic animals and fowl, as well as wild animals, according to Pro- fessor Peacock’s tabulation: Dog, thirty-five years; horse, forty ; cow, twenty-five; cat, forty; hen, thirty; goose, fifty-seven; lion and tiger, twenty- five. Salmon and sharks may live to te 100, eels to be sixty; one toad is known to have reached the age of thirty-six, and an alligator that of forty. The shortest lives are among the insects. The winged male of a species called Stylops may live only from one to three hours. The house fly lives about thirty-four days; on the other hand, ant queens have reached the age of thirteen years. A fire beetle holds the insect record, having been found alive in a piece of wood it must have entered thirty-seven years before. RUSSIAN EX-GENERAL NOW MENDS RADIOS Makinc balky radio sets behave is now the peaceful occupation of a former major general in the Imperial Russian Cavalry, George C. Oustimovich. The excitement and clamor of leading the Czar’s horsemen in the days before the war have been supplanted by the quiet of a small radio repair shop in New York City. When Oustimovich arrived in Amer- ica, after the Russian Revolution, he put his knowledge of radio to practical use and opened up a little shop where, in- stead of a flashing saber, he now wields harmless pliers and screw driver, adjust- ing and testing the rebellious instru- ments brought to him for repair. George C. Oustimovich, once major general in Russian Cavalry, repairing a radio set inhis shop. - APR oan ek a...

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1930 the only J e@x- F are Tipe 200; also aded s the hich day. 3 are | the ined l, as Pro- cow, ty; nty- 100, 1 to and ‘test iged live use the hed etle een Lust ore. is ner ian ‘he the the liet ew er- ut ise in- ids st- Apri, 1930 POPULAR SCIENCE MONTHLY 67 An Arctic Scene in New York. This wind-swept view of Bering Sea with Arctic birds disporting themselves looks exactly like the real thing, but actually it’s no farther north than the American Museum of Natural History in New York. Driving Taught in Office. Chief Safety In- structor L. B. Gordon, of the Pacific Telephone and Telegraph Company, is displaying a board, equipped with map of San Francisco and showing traffic problems, which he uses in teaching the Company’s hundreds of chauffeurs how to drive. Ship Model Carries Crew. This remarkable twenty-six-foot Diesel- driven model of the North German Lloyd Liner Columbus recently cruised up the Hudson River at New York carrying a complete crew of two. Homemade and Simple. This little 480-pound airplane, designed by Earl Clark, right, and ‘built by him and his brother, Donald, left, of Buffalo, N. Y., has only two wooden struts, five steel tubes, and four brace wires. It carries a 28-horsepower engine. ts Building Their Own Abbey. Monks of Devon- shire, England, started work on a new abbey twenty- three years ago. They have done all of the work. Barge Is a Counterweight. Loading steel barges on the River Tyne gave this ship a danger- ous list. So the captain swung a barge on the opposite side to keep his boat from foundering. POPULAR SCIENCE SCRAPBOOK

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ee Ss 2 Acne — SF $a ; EE AA OY EW ES I MBER. a <2 he _- en ee POPULAR SCIENCE MONTHLY ~ New Household Devices Appliances, Machines, and Utensils Invented to Save Labor and Add to the Comfort of the Home APRIL, 1930 4 a ,

Sweeping the kitchen is simpli fied by a sanitary dust chute of steel built into the baseboard. A swinging door opens at the touch of a foot lever, and sweepings go down the chute to the basement. The curtain “hold-back” at the right consists of a curved metal arm pivoted on a sup- port fastened to the window frame. It draws back the curtain to admit more light. A new type of electric exerciser, pictured above, requires no bulky stand nor cabinet. It may be clamped quickly to a door or even a window sill. When not in use it can be tucked in a drawer, or placed in a bag for traveling. This electric “floor heater” does not concentrate its heat in a beam, but radiates it in all directions. Its stream- lined base facilitates the movement of rising air cur- rents that warm the room. Built up in sections, like a sectional bookcase, a new electric range may be made as simple or elaborate as desired. By adding parts to the basic unit consisting of

Compact and attractively cased, the two-purpose raci- ant heater at the right is de- signed especially for a wom- an’s dressing table, where it serves as a hair dryer. At other times it warms a cold spot in a chilly room.

base and oven, fifty combi- nations are possible. The range can be adapted to right- or left-handed users. Above are two views of convenient breakfast table tongs for handling a hot boiled egg without danger of “burning the fingers and without the use of a napkin. When the han- dles are squeezed, the curved jaws of the device grip the egg firmly while exposing one half of the shell for slicing with the knife.

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» 1930 CS ciser, ; no may or or ot in wer, J Aprit, 1930 POPULAR SCIENCE MONTHLY 69 The handy wall brush at the right has near its head two hooks, one of which will take down a picture ‘and replace it; the other pulls down window shades that have soared skyward. Triangular brush makes it easy to clean corners. see8 Here is an electric clothes washer without a motor. It operates magnetically, much like a doorbell, to agitate the water in the vessel and force it through the wash. In the cover is an “impeller” which vibrates 120 times a minute, having the effect of agitating the water and suds. Dishes are less likely to be chipped when washed in this papier-maché dish pan. The composition is not hard enough to damage a plate that drops on it, yet is firm enough to make a_ serviceable basin. A combination clothes washer and ironer. After clothes have been washed in the machine at the left, the twenty- six-inch ironer roll at the right irons them neatly. It does not interfere with the washing operation and may be left attached: to the washing apparatus permanently, A new electric bottle warmer heats the baby’s milk to just the right temperature, then shuts off automatically. At the same time a signal light flashes to indicate that the milk is ready. The diminutive household jack shown at the right is handy for such purposes as lifting a heavy stove to replace a leg, or rais- ing one corner of a piece of furniture. It is sturdy, and ex- erts a push of 500 pounds. One side of the iron rest at the — is flush with the ironing that the ison need uabhe Riad. The other three sides are raised to keep the iron from falling off. Under the base is a layer of asbestos to pre- vent scorching the board or cover. No lifting is required to dump this outdoor incinerator. Mounted on a stand, a turn of a handle swings it and drops its ashes and "residue into a pail for disposal. While the contents are burning, the handle shifts them about, thereby aiding complete combustion. ee ee a 0

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a ee ee ee oe ——— emce MONTHLY ARCHIMEDES ae oe cience Fe Travis Hoke, Editor Raymonp J. Brown, Managing Editor Arraur WaKELING, Home Works op Editor Aurrep P. Lane, Technical Editor IsraEL Doskow, Art Editor E. E. Free, Contributing Editor Published Monthly by Popular Science Pe Company, Inc., 381 Fourth Avenue, New York Ci le Copies Twenty- five Cents. In the United States and Its » Doesess ‘ossessions and in Canada, $2.50 the Year. In All Other Countries, $3.00 the Year. What Is the Lesson of Air Crashes? ITHIN the last few months a succession of air trage- dies has shocked America. Worst of all, they have occurred on established, scheduled air lines. The victims have been passengers who rightfully expected safe transportation. It is easy to say, and true, that such accidents are inex- cusable. But the causes should be determined, so that no more will occur. Almost every alibi has been offered—weather, possible mechanical failure, Acts of God. Nobody, though, has offered the obvious suggestion that the pilots may have been temperamentally unqualified to fly passenger planes. A pilot must have had a certain number of flying hours, or he would not be licensed to carry passengers. But the mere possession of a license does not mean everything. Suppose a former air mail pilot becomes a transport pilot. The nervy young pilots who fly the mail may not be actually encouraged to risk their lives in bad flying weather, but it is no secret that they take a certain pride in “getting through.” That pride has no place in passenger transport by air—where the decision as to whether the plane shall fly is left with the pilot. It is an air mail pilot’s privilege to risk his own life, if he wishes; no transport pilot has the right to risk his passengers’ lives. At present most transport companies require that their pilots be young men. older pilots, aviators of balanced judgment. Certainly repeated emphasis on safety should be made by the operators of pas- senger air lines and responsibility for taking the plane in the air should not be invested in the pilot alone. Pilots should be forbidden to fly in bad weather even if they believe they can get through. This is the ordinary practice in Europe, where passenger aviation was well established long before it was even tried in the United States. Morons at the Wheel ipower morons can be automobile drivers is no surprise to motorists. Not only will they readily agree with this state- ment of Dr. Knight Dunlap, in charge of the National Research Council’s tests of drivers, but they will go farther and assert, from their own experience, that many of the drivers they have met on the road are morons—or worse. But Dr. Dunlap’s assertion that mental speed and high in- telligence do not necessarily make a good motorist is of real interest. He insists that the honor college student and the s moron can both be trained to be good drivers, who perform POPULAR SCIENCE MONTHLY It may be that passenger aviation calls for — APRIL, 1930 automatically and efficiently all the motions necessary in the operation of a motor car. And there is no substitute, he says, for the kind of training he suggests, which is nothing more nor less than common sense practice—and plenty of it—in handling clutch, brake, and gears. Dr. Dunlap approves license tests because they compel a driver to learn at least something. What this investigator has discovered about accident pre- vention through education of the man at the wheel is detailed on another page of this issue. It is based in part upon a series of unique psychological tests—the first of their kind ever at- tempted—designed to find out what an auto driver thinks about. Safe Gliding to Be Safer HE United States Department of Commerce announces that gliders, like airplanes, are to be licensed by the Gov- ernment. The machines must meet definite tests of airworthi- ness, and in towing-gliders an approved device for releasing the cable will be required. Already, 110 applications have been received. This decision is a wise one. When properly constructed gliders are flown under normal conditions, the sport is as safe as bicycling. The chief danger in gliding at present is the homemade, makeshift machine that is structurally unsound. The licensing of gliders by the Government, by weeding out the unfit machines, will give added emphasis to the safety of gliding. It will encourage many to join in this stirring new sport of the air. More of the Same Still Needed NEW S that the House of Representatives has acted to pro- vide the United States Patent Office with increased funds will be little comfort to the inventor still waiting, after two or three years, for his patent. But it should tend to speed up the patent machinery, which of late has creaked dismally. The bill just passed by the House appropriates $3,474,930 for an increased patent staff and for higher salaries. This will provide the Patent Office with 110 more examiners and thirty additional clerks. An extra Assistant Commissioner and an- other Examiner-in-Chief, to help the Patent Office’s Board of Appeals catch up with its work, also will be available. This is a move in the right direction, as is the Personnel Classification Board’s recent action in boosting the grade and salary of Principal Examiners. The benefits are twofold. One will be to reduce materially the disgracefully long time often required to get a patent. Another will be to make a patent more valuable, by assuring a higher grade of examiner to pass on the application. It has been common knowledge that a United States patent was less authoritative, for instance, than one granted in Germany. It was merely prima facie evidence, when issued by the United States, that the idea was patent- able, and was no guarantee that it had never been patented. They Are Saying— HE crass, selfish, blatant advertising fostered over the air by avaricious stations will in time kill public acceptance of broadcasting.” —Dr. Lee De Forest, inventor of the audion; “father of radio.” “The antiquity of man is as great on the American conti- nent as in any other terrestrial locality.” —P. E. Cox, archeolo- gist, State of Tennessee. “‘Man already possesses ten senses, and in a few million years his descendants will have developed a lot more.’’—Dr. Karl G. Miller, professor of psychology, University of Penn- sylvania. “Excess noise is a contributing cause in street accidents, and tends to keep city dwellers constantly keyed up to the fighting pitch.” —Dr. Shirley W. Wynne, health commissioner, New York City. “The average man of today cannot get into a Crusader’s suit of armor; he is bigger and taller than his medieval an- cestor and his ‘shoulders are too broad.’”’—Dr. Joyce Partridge, London surgeon. “In fifty years, there will be an automobile which will use a rotary engine, go sidewise as well as forward and backward, and be gearless.’”—Roger W. Babson, statistician. “A general knowledge of fundamental physical science is often more valuable than special training and routine.’’—Pro- fessor Albert Einstein. AP amy plifi grid Tha

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130 the YS, nor ing Sts re- led ‘ies at- iks V- hi- ng ed afe id. put of ew rO- ds he ‘ill ty n- el t- d. Apri, 1930 POPULAR SCIENCE MONTHLY 71 How Many Tubes Do You Need? Number Is Only One Factor in Performance of Set— Design of Circuit is Important OUNTING the num- ber of tubes in a radio receiver is no way to judge its quality. It is, in fact, no more accurate than to judge an automobile by the num- ber of cylinders in the engine. There is, for example, an eight-cylinder car on the market that develops 265 horsepower. Another has a sixteen-cylinder engine that develops 150 horsepower. In a radio set the number of tubes used is important, but it is not the only deciding factor. About the only thing that the number of tubes in a set actually determines is the upkeep cost. The more tubes used the more it is going to cost for electric current to run the set, and the larger will be the bill for tube replacement. In the early days of battery operated radio sets there were but two types of vacuum tubes available—the so-called “hard” or amplifier tubes used for radio or audio amplification and the so-called “soft” tubes that were, because of their lower vacuum, particularly suited for detection. As the desirable qualities of a vacuum tube became more clearly defined, new tubes were developed with specialized characteristics. Today there are special tubes for radio-frequency amplification, as for example the screen grid tube. The type 227 A.C. heater tube comes nearest to being the present-day all- purpose tube, and there are several types of power tubes particularly suited only for use in the last audio amplifier stage. Before the radio engineer designs a receiver, he must decide what char- acteristics the proposed set is to have. Then he strives to obtain these with the minimum number of tubes. Experience has shown that, under modern broadcasting conditions, three or four tuned stages are necessary to give adequate selectivity. The sensitiveness of the circuit must be such that satisfac- tory reception can be obtained from short antennas in unfavorable localities. Ar the signal is amplified at radio frequency and at the same time sorted out from signals from other stations, it must be rectified or detected and then amplified at audio frequency. In the radio-frequency stages the am- plification obtainable from three screen grid tubes represents the practical limit. That amount of amplification will always mee Preparing radio receivers for test in Popular Science Institute radio laboratory. The set at the left of the picture has fourteen tubes, the other has eight. By ALFRED P. LANE get down to static level, and any addi- tional radio-frequency amplification would, therefore, be useless. Of course, it would be possible to design a radio set with four, five, or even six screen grid tubes, but it wouldn’t be any more useful in bringing in distant stations than a set using three. Of course, the mere fact that a set has three screen grid tubes in the radio-frequency stages does not guar- antee that it will give maximum per- formance, though it does point to that possibility. In the detector stage, only one tube is necessary, and in the audio stages only three can be used to any practical advantage—one as the first audio stage and two of the power type in the last or push-pull stage. T= possible volume on local stations with satisfactory tone quality is indicated to some degree by the tubes used in the audio amplifier end of the set. In two well-designed receivers, the one using only a single 171A tube obviously cannot give the volume, with good tone quality, obtainable from a set with two type 245 tubes in a push-pull circuit. Although push-pull amplification, if properly used, will give the finest tone quality, poor audio transformers in a push-pull circuit will spoil the tone qual- ity just as they will in any other type of audio amplifier circuit. So much for the tubes that actually handle the broadcast signals. In electric sets made today other tubes also are needed; at least one, sometimes two, and, in special cases, even three. If the set is of medium power—that is, one using up to two 245 tubes in the last audio stage—a single type 280 rectifier tube will take care of rectify- ing the necessary current for the B circuits of the set. In elaborate receivers, two type 281 tubes are used in the rectifier circuit, and in some sets a third tube is used which functions as a ballast tube to compensate for changes in the electric light current voltage at various times of the day. To sum up, the finest re- sults can be had from a cir- cuit using not more than three screen grid tubes, one detector tube, one first audio amplifier tube, and two power tubes. Seven tubes in the radio circuit and one recti- fier tube gives a total of eight tubes as the maximum number that can effectively be used. If still greater volume is desired without increase in selectivity or distance getting ability, one more rectifying tube may be added. It is easy to see, therefore, that a set advertised as having ten, twelve, or fourteen tubes is not likely to give re- sults in proportion to the cost of operat- ing it. Furthermore, the mere fact that a set has the maximum desirable number of tubes does not mean that it is going to give maximum results. The entire cir- cuit must be carefully worked out in order to obtain full results from the tubes. That is why an eight-tube set sometimes does not equal other sets which use fewer tubes but are better engineered. It must be clearly understood that tone quality and volume on local stations depend entirely on the tubes in the audio amplifier end of the circuit, and not at all on the number or arrangement of the screen grid tubes in the radio-frequency circuit. If the purchaser is not interested in distance and only requires a moderate degree of selectivity a simpler circuit will satisfy his requirements. ‘toe or at most three, type 227 tubes in the radio-frequency circuit instead of the more expensive screen grid tubes will give him the necessary degree of selectivity and more than* ample sensi- tiveness. If less volume, but equally good tone quality, is required, together with maximum sensitiveness and selectivity, two or three screen grid tubes are re- quired in the radio-frequency stages, but the audio stages may consist of only two tubes, one 227 in the first stage and a single 171A tube, or preferably two 171A tubes, in the second stage.

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rs pune pas > vw 2 TET SS ors wae = —— ee pz ——— se ON BIE POS FIGS Te TYEE OE BY ae ee Ne. oe — sr POPULAR SCIENCE MONTHLY APRIL, 1930 HELPFUL KINKS FOR THE RADIO FAN Novel Condenser Capacity Test Drop Cord, Socket, and Electric Light Bulbs Reveal Condenser Secrets—Hooking Headphones to A.C.Set EASURING the capacity of a fixed condenser is quite a problem to most radio fans. Condensers sold over the counter are, of course, marked with the capacity in micro- farads. It is, therefore, easy enough to purchase a condenser of any desired capacity. The problem is to determine the capacity of condensers after the label has become defaced or de- tached, or to measure the capacity of a condenser in a factory built set which in all probability is not marked. A fixed condenser of any capacity placed in a circuit will prevent the fluw of direct current, but alter- nating current will flow through the condenser in quantity depend- ing on the voltage, the frequency of alternation, and the capacity of the condenser. These facts provide a simple way to test condensers where a rough approximation of the condenser capacity is all that is required. In any radio circuit, unless a condenser is used in a tuned portion of the circuit, the capacity can be varied within wide limits. This is true also of the power or filter circuits which supply the B current. That is why a rough approximation of condenser capacity will do. A method of testing condenser capacity is illustrated. Of course, a source of alternating current is necessary. The 110-volt A.C. current from the electric light line is suitable. Connect an electric light socket to one end of a twisted drop cord. Attach a plug to the other end. Then cut one of the two wires which, twisted together, form the cord. Unwind each of the two ends for a few inches and solder each end of the cut cord to a separate piece of stiff wire, such as bus wire. Then tape each joint thoroughly, allowing a quarter of an inch of the bare wire to project from the tap- ing. Place an electric light bulb in the socket. Push the plug into a wall socket and if the bulb lights up when the two test points are touched together the test circuit is ready for use. Electric light bulbs of ten, fifteen, twenty-five and fifty watts should be obtained. The capacity of a condenser in microfarads is determined by connect- ing the test points to the terminals of the condenser and estimating the flow of current by the effect on the light bulb in the socket.. If, for example, the condenser to be tested has a capacity of one half Working out the simple condenser capacity test method in the radio laboratory of the Popular Science Institute. microfarad, the ten-watt bulb will glow red and the fifteen-watt bulb will produce a glow that is barely perceptible. If the condenser has a capacity of one micro- farad, a fifteen-watt bulb will glow red and the twenty-five-watt bulb will be very dim. With a two-microfarad con- denser the twenty-five-watt bulb will glow a dull red and a three-microfarad condenser will make the twenty-five- watt bulb bright red. The fifty-watt bulb will be very dim with a four-micro- A B C’s of Radio \ HILE distortion obviously re- sults in poor tone quality from the loudspeaker, podr tone quality is not necessarily distortion. As com- monly used the terms “distortion” and “poor tone quality’ do not have the same meaning. Poor tone qual- ity is the term used to label the out- put of a radio receiver so poorly de- signed or built of such poor parts that all reception, whether at high or low volume, does not even approxi- mate true reproduction. Distortion, on the other hand, is generally con- sidered to be the inaccurate reproduc- tion resulting from overloading the tubes or operating them under im- proper conditions. Every radio receiver has a distor- tion point. If the volume control is pushed too far on local stations the distortion point will be reached, no matter what tubes are ‘used. farad condenser, but will be bright red with a six-microfarad con- denser. If on testing a condenser of any capacity the bulb appears just as bright as it does when the test points are connected directly to- gether, it is an indication that the condenser is short-circuited or blown-out. Headphones Aid the Partly Deafened F ONE member of the family is hard of hearing the radio re- ceiver usually has to be turned on so loud as to be objectionable to the rest of the family. The solution is to add a pair of headphones. If it is a modern electric set the chances are it is fitted with a dynamic speaker, and, in such a set it is common practice to use a special output transformer of the step-down type which feeds directly into the voice coil of the dynamic speaker. It is not possible with such an arrange- ment to connect the headphones in paral- lel with the speaker cord. The simplest solution is to connect the headphones across the input terminals of the output transformer inside the set and connect in each wire a two-microfarad condenser having a voltage rating not less than 300. If the receiver uses a push-pull circuit in the last stage, the leads from the head- phones should be connected to the outer terminals of the input winding of the last transformer. In many sets it is impossible to get at these connections without tak- ing the chassis out of the case and partly disassembling it. In such cases it is possible to make external connections to accomplish the same results. Locate the plate prong of the power tube, or in the case of a push-pull circuit of the two power tubes, and connect the headphones across between these two prongs by way of the condensers as above mentioned. Be sure | to include in series with the headphones a variable resistance that can be adjusted to at least half a million ohms. The set’s volume control will give the proper volume from the loudspeaker, and the person using the headphones can ad- just the volume from the headphones by the separate variable resistance. - The fixed condensers are needed to in- insulate the headphones from the high voltage applied to the plate or plates of the power tubes, thus protecting against dangerous shocks.

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1930 right con- any it as test to- the or Av y is re- | on the n is If it mic t is cial wn the It ige- ral- lest

AprRIL, 1930 POPULAR SCIENCE MONTHLY 73 Shifting Antenna to Avoid Static

OUTDOOR AERIAL

Fig. 1. Howalongantenna may be outside the zone of man-made static shown by shading. HE radio antenna is an indis- pensable link in the chain of broadcast reception. It brings the radio-frequency impulses sent out by the broadcast transmitter into the radio receiver. No set can work without one any more than a person can see without eyes. Even sets sold as ‘‘antennaless”’ really use an antenna. It may be only a few inches of wire inside the cabinet, or perhaps the electric light wiring is

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utilized, but some substitute for an ordinary antenna is there, never- theless. , Furthermore, the quality of the reception depends largely on the skill with which the physical dimensions of the antenna are fitted to the radio peculi- arities of the particular location where the set is to be used. The variation in the characteristics of different radio receivers together with the wide differences in the radio characteris- tics of different locations make it impos- sible to lay down hard and fast rules as to what is or is not the best radio antenna. A combination that is exactly right for one location with a certain set may be entirely wrong in another location on the same set or on a different set. Moreover, the requirements of radio set owners differ within wide limits, and to make matters still worse, there are many widely circulated but erroneous beliefs con- nected with antennas. The desired result, of course, is to bring in the broadcast signal with the minimum amount of interference from natural and man-made static. HE current belief that the shorter the antenna the less trouble with static interference of any kind is wrong more often than not. Under certain con- ditions, reducing the length of the antenna may increase the amount of interference from man-made static. Static, whether of the natural variety produced by atmospheric conditions or of the man-made kind caused by the operation of electrical machinery, enters the radio set by way of the antenna, just as does the wave from a broadcast sta- tion. There is no known way to sort out and eliminate static of either description. Fig. 2. An indoor antenna under such conditions may be entirely within the man-made static zone. All that can be done is to alter the antenna so as to reduce the amount of static it picks up in proportion to the strength of the incoming broadcast wave. . F THERE is no man-made static to contend with, natural static some- times can be reduced a trifle by using a short antenna. Reducing the length of the antenna also produces an apparent improvement in selectivity with, of course, a falling off in the strength of the signals from distant broadcast stations. A short antenna generally has less high frequency resistance than a long antenna, and because it has less effect on the first tuned stage in the radio circuit there is an actual improvement in the selectivity of this circuit with a short antenna. But the actual improvement is small com- pared with the apparent improvement, which is simply the result of the reduced signal strength. While no change in the antenna length can affect any material improvement in the ratio of broadcast signal strength to natural static strength, it often is possible to reduce the interference caused by man- made static. Possibilities along these lines depend on the location of the source of the man- made static; that is, the location of the machines that are causing the trouble. If the man-made static is produced by the overhead trolleys on an electric rail- way and is radiated from the overhead wire for miles in every direction, or defective apparatus such as a partly broken-down insulator on the high ten- sion power wiring is similarly radiating No Known Way to Eliminate Trouble, but Altering the Aerial May Reduce Disturbance in Proportion to Strength of Incoming Wave ' By JOHN CARR static for long distances, changing the antenna can have but slight effect. There are, however, thousands of cases where the man-made static is produced by some piece of electrical apparatus in the same building with the radio receiver. This is the situation in many apartments using elevators and other electrical apparatus. In such cases, increasing the length and height of the antenna frequently will improve recep- tion from distant and local stations alike. A large part of a long antenna may be out- side the zone of influence of the man- made static. Then, when a strong signal is picked up, it is possible to turn down the volume control to the point where the set is relatively insensitive to the man- made static picked up from the portion of the ahtenna affected by the local machin- ery. Figures one and two illustrate this possibility. Figure one shows an outdoor antenna with the shaded area indicat- ing the extent of the man-made static produced by some piece of machinery in the house. Note that much of the outdoor antenna is outside this zone of influence. Figure two shows exactly the same situation except that an indoor antenna is substituted for the outdoor antenna. Note that in this case the entire antenna is within the zone of influence of the locally manufactured static, and more static will be picked up while at the same time less signal strength is obtained from the broadcast station. F COURSE, physical limitations in many cases make possible the erection of an antenna only in one direction and of a given length and height, but where it is possible, it always is worth while to experiment with antennas strung in dif- ferent directions and at different heights. A single-wire, horizontal antenna often displays marked directional characteris- tics. When it does, it almost always receives best the station opposite to the direction toward which the free end points. Natural static frequently dis- plays some directional characteristics and in many localities tests may reveal that some desired station can be received with much less static interference merely by a shift in the direction, height, or length of the antenna. It may be well to point out that there is no particular merit in the shape of the antenna nor the material of which it is made, provided the wire is of some non- magnetic material of good conductivity. = pS nowt en : re , 4 f i { < * ites eS oe sey

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ac a ERE RI hw ier tn “weeps ame Bosemae Ae~ TRS OR spite er 8, ae itis knee eperee= e Te, es > 74 POPULAR SCIENCE MONTHLY APRIL, 1930 Your Car Is Pigeon-Toed Gus explains why the front edges of tires should be a fraction of an inch closer than the rear By MARTIN BUNN . HIS sure is my lucky day, Gus,” smiled Pop Topham as _ he stopped his shiny new car in front of the Model Garage. “What did you do—sell that corner plot for about twice what it’s worth?” Gus Wilson winked at his partner, Joe Clark, as the two garage men stepped up to Topham’s car. “Oh, nothing as good as that,” replied Topham. “But I just skidded into the curb and didn’t hurt the car. Usually when I get something new, I manage to ruin it, first time I use it. A fellow crum- bled a mudguard on my last new car be- fore I’d gone ten miles.” “T remember that,” said Gus. ‘Sorry to hand you bad news now, Mr. Topham, but that skid did do some damage. Look at the tracks of your tires. The wheels are out of line. Either you sprung the frame when the wheel hit the curb or you moved the back axle on the spring.” “T might have known it!’ Topham groaned. Gus leaned over to inspect the rear end of the chassis. “I guess you’re lucky after all,” he said at last. “It’s not a sprung frame. Run your car inside and we'll line up the axle on the springs again.” Joe swung the door open and Topham drove in. Gus followed, carefully exam- ining the tracks of the tires. “Have vou noticed anything funny about the steering?” he asked. “Tt doesn’t seem to steer so very easy.” “That’s because the front wheels are out of line a bit, too,” Gus explained. “‘And from the looks of the running gear, I don’t think your front tires are going to last very long.” “‘What’s the matter with them?” ques- tioned Topham. “They look all right.” “There’s nothing the matter with the tires, but the front wheels don’t line up; and when that’s the case, you can figure on buying one new tire after another. Just a minute and I'll show you,” said Gus; and he brought out the measuring instrument designed to check the align- ment of the front wheels. “T could do this with a tape measure,” he said, “but it’s much easier with an out- fit like this. See—the front edges of the front wheels are half an inch farther apart than the rear edges. When the wheels are “Look at the tracks of your tires,” Gus said. “The wheels are out of line. Either you sprung the frame when the wheel hit-the curb or you moved the back axle on the spring.” pointed as nearly straight ahead as you can get them they toe out. After I straighten out the rear of the car I’ll ad- just the tie-rod so that the wheels toe-in just about an eighth of aninch. The front edges of the tires should always be an eighth of an inch nearer together than the rear edges.” “How do you know where to make the measurements?” asked Topham interest- edly. “The wheels are tipped anyhow, and I don’t see how you figure where to apply the tape.” “T’ll say they’re tipped,” said Gus. “The front wheels should have toe-in and camber and the king-pins should have a certain amount of caster.” “They seem to need lot of things all at once,” said Topham, gloomily. ‘What do all of those words mean?”’ “Well,” said Gus, “camber is the GUS SAYS— VV HEN you’ re figuring on buy- ing a car remember that swell furniture in the salesroom don’t make the car run any better or last any longer. And when you need service, as you’re bound to after a while, you don’t get it in the salesroom. What counts is whether the agency has a service station fitted with modern tools and manned by real mechanics. A fancy salesroom is all right in its place, but the wise buyer always investigates the service station. amount the wheels tip—usually about two degrees. The outer end of each axle drops a little from the horizontal so that where the tires touch the ground they are closer together than at the top. The idea is to have the point where the tires hit the road brought in under the steering knuckle. That makes steering easy. Modern cars don’t have as much camber as the old-timers. They’re made with better steering knuckles now and more ball bearings.” “‘What’s the caster?” Topham asked. “The caster is the tipping of the king- pins so that the top leans back. It’s kind of hard to explain, but if you haven’t any caster, steering is mighty hard. The cen- ter line of the steering axis in an auto- mobile is the king-pin. If you carried it on to the ground in theory, it ought to be ahead of the point where the tire makes contact with the road. You know how you can ride a bicycle with your hands off the handlebars? That’s due to the caster action. So is the tendency of an auto- mobile’s wheels to straighten out after being turned. I once drove a car fifty miles that had an axle assembled all wrong. There wasn’t any caster or tipping of the king-pin. By the end of the trip both arms were lame just from trying to keep the steering wheel straight.” “Good grief!” gasped Topham. “I never realized there was so much to the steering gear of an automobile.” “‘There’s more yet,’”’ Gus smiled. “Even if the caster and camber and toe-in are right, you have trouble if the wheels wob- ble. What’s (Continued on page 154)

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ee ~~ - Sa ve a woe AprRIL, 1930 POPULAR SCIENCE MONTHLY 75 POPULAR SCIENCE HOME WORKSHOP Articles on Furniture, Models, Toys, Sporting Equipment, and All Forms of Craft W ork—Better Shop Methods—T he Shipshape Home Fig. 1. The cabinet has a covered drawer which serves as a desk for the telephone. EW pieces of homemade furniture can equal the telephone -cabinet illustrated above in convenience and attractiveness. Its construc- tion is such that it can be made easily in a motorized home workshop; or, if no lathe is available, the legs can be turned to order at a wood turner’s or cabinet- maker’s shop. This project has been included in our series of articles on the use of woodwork- ing machines especially to demonstrate the use of small portable sanding ma- chines, which are designed to bring any surface to the degree of smoothness re- quired for the application of a really high- grade finish. Two types of these ma- chines are illustrated, a drum sander ix Fig. 2 and a belt sander in Figs. 3, 5, and 6. The importance of thorough sanding should not be overlooked by the amateur woodworker. The finest varnish, lacquer, and enamel will not conceal tool marks or superficial blemishes. Indeed, the fin- ish tends to magnify all defects; hence the necessity for obtaining a perfectly smooth surface before any finishing is done. All the surfaces, of course, can be smoothed by hand, but the amateur craftsman undoubtedly can obtain better and infinitely quicker results through the use of a portable sander. It can be oper- ated as easily as a hand plane and thus Making a Convenient Telephone Cabinet By WILLIAM W. KLENKE makes sanding more of a pleasure than a monotonous chore. At the present time there are on the market three principal types of small sanders: the continuous one-piece belt machine, the drum sander, and the disk sander. The last mentioned is operated by means of a flexible shaft and is not used as extensively for cabinetwork as are the other types, which will be dis- cussed in this article. Each sander has its especially good points, and excellent results can be ob- Fig. 2. This drum type of portable sanding machine has a bag which catches the dust. tained on either type of machine. The continuous belt sander (Fig. 3) has, as its name implies, one piece of sandpaper spliced together in the form of a belt, which revolves around two cylinders. The flat surface of the machine between the cylinders is what serves as a backing for the paper in sanding flat surfaces. Be- cause of the relatively large expanse of surface that comes in contact with the wood being sanded, the maxi- mum allowable cut is somewhat limited with this type of machine. The belt sander-is light and easy to operate and can be used with a great de- gree of accuracy. One of the advantages of this machine is the ease with which the sandpaper can be changed (Fig. 6). By using a special table attachment (Fig. 5), the sander can be converted into a bench machine for use in squaring table legs, rails, and similar parts. Curved work can be sanded on one of the cylin- ders, so that this type is invaluable for Fig. 3. The continuous belt type of sander is operated much as an ordinary hand plane and just as easily. sandpapering all varieties of surfaces. The drum sander (Fig. 2) has a revolv- ing felt-covered cylinder over which sand- paper is placed. The sole of this sander is adjustable for the thickness of the cut desired. It is capable of taking a very deep cut and, of course, can be adjusted for a very fine cut also. Indeed, the cut- ting capacity of this machine is perhaps its outstanding feature. Attached to one side of the machine is a large bag which catches the fine dust as it comes from the wood. By removing the sole, this type also makes an excellent sander for concave surfaces. In constructing the telephone cabinet illustrated in Figs. 1 and 4, almost any furniture wood may be used, but it must be reasonably hard and strong be- cause the legs are turned to a small diameter. A good mate- rial is maple or birch, which can be stained or lacquered to suit the individual taste and to match walnut or mahogany. The steps in the construction of the legs and rails are as follows: Step No. 1—The Stock. Get out all stock on the jointer and circular saw to the sizes indicated in Fig. 4. Step No. 2—Turning the Legs. Turn the legs to the design, being careful to obtain clearly defined, well-matched profiles. Step No. 3—The Joints. Either mortise and tenon or dowel joints may be used. If the simpler dowel joint is preferred, all RA a a

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min Sat ti E F b J POPULAR SCIENCE MONTHLY and smooth it with the portable sander. The top then can be fastened to the legs and rails by any meth- od preferred. The construction of the cabinet portion is as follows: Step No. 1—Stock. Cut SOY, Sh" ovERLAY USE EITHER MORTISE ¥8 NO RAIL IN FRONT TURNED L= FRONT VIEW STOCK 144" SQUARE SIDE VIEW the stock to size on the jointer and circular saw, and use a jig saw to cut the three telephone book par- titions toshape. |.” Step No. 2—Joints. On the circular saw, cut all the necessary joints, following the working drawing. A rabbet should be cut in the sidepieces to receive the back. Step No. 3— Assembly. Make a trial assembly. of the back in place. Step No. 4—Cleaning Up. A portable sander, used as illustrated, will save a great deal of labor and besides do a perfect job on the broad surfaces of the cabinet. Step No. 45— Miscella- neous. Glue on the various Fig. 4. Dimensions of the telephone cabinet. Any reasonably hard wood can be used in the construction of this project. the holes can be bored quickly and ac- curately in the lathe. If you choose the mortise and tenon type of construction, the mortises can be bored out ready for the hand chiseling operation, and the tenons can be speedily cut to shape on the circular saw. Step No. 4—Assembly. First glue to- gether the legs and rails forming each end of the table, and allow the work to dry between clamps. After the glue is hard, assemble the remainder of the table, being careful to get all of the parts square and in line. Step No. 5—The Top. If your stock is not wide enough so that one piece will serve for the top, it will be necessary to join several pieces together. True all of the edges on the jointer and lay out the pieces for doweling. Glue them together; and when the glue is hard, dress the surface overlay panels, nail the molding in place, and cut the drawer stock on the circular saw. Hang the doors after all other operations have been completed. Step No. 6—Cleaning Up the Entire Project. Remove any excess glue with Fig. 5 (below). Table attachment for use on a belt sander. Fig. 6 (at right). Remov- ing the sandpaper from the belt sander. es the parts to be sure that: they fit, and then assetpble , and glue the sides and nail APRIL, 1930 a sharp chisel and thoroughly sandpaper the entire cabinet with No. 0 and No. 00 sandpaper, slightly rounding all the edges. Step No. 7—Finishing. This cabinet, with its overlay on the doors, drawer, and sidepieces, and with its graceful legs, is an excellent project for the application of an antique finish or a two-tone effect in lacquer. To obtain an antique effect, the wood should be stained to imitate mahogany, walnut, or antique maple. I prefer to use a water stain, but prepared penetrating stains will also give good results. When the stain is dry, apply a very thin coat of white shellac. Then sandpaper the entire surface with No. 00 paper to cut the raised fibers. Sandpaper all the high parts of the turning, the edges, and any place where natural wear would occur until you are almost down to the bare wood. Follow with a coat of paste wood filler of the correct shade. The filler gives a mellow tone to these artificially worn places. Allow ample time for the filler to harden and apply three or four coats of white shellac, rubbing each coat lightly with sandpaper and the last coat with powdered pumice and oil (crude oil is to be preferred). Of course, if you have a spraying outfit, lacquer can be used in place of the shellac. In an article in the May issue, the construction of the bench will be given. This is the ninth of a series of articles in which Mr. Klenke, through the courtesy of various manufacturers, 1s demonstrating the use of many new motor-driven home workshop machines of both the combination and individual types now used so extensirely. How to Make a Railing for a Motor Boat Model EING unable to obtain screw eves suitable for use as stanchions in the construction of a railing for a motor boat model (that shown on PopuLar SCIENCE MonTHLY Blueprints Nos. 63 and 64, listed on page 111) and not wishing to Fig. 1. By selecting the proper size hinge you can make railings for a model of any size. pay the high price for regular model stanchions, the author made neat sub- stitutes from the pins of ordinary hinges (see Fig. 1). The hinges can be obtained in various sizes-at five or ten cents a pair. By select- ing the right size, it is possible to make a railing for a large, small, or medium size model. The pins are removed from the hinges and the caps or knobs pulled from the pins with a pair of pliers (Fig. 2). This is done to simplify the drilling of the holes for the railing. The author tried to drill the holes with the caps on the pins but found it difficult because the pins are harder than the caps. The pins are then cut to the right length and inserted in holes drilled in the deck. After the caps have been slipped on the wire railing, they are moved to the correct position, and the railing is-bent to the de- sired shape.—HENRY MARTIN. “F me) Novell [wae z ¢ —— y WALLED i Fig. 2. The knobs are removed from the pins DECK — to allow the holes for the rail to be drilled. “il hi i

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ApriL, 1930 POPULAR SCIENCE MONTHLY 77 Stagecoach Model Making ITH the main structural de- tails of the Diamond Tally-Ho model completed, our little stagecoach begins to take on the lines of the romantic old coach from which it was copied. All that is left to do is to attach the platforms, upholster the interior, place the seats, and apply the paint and decora- tions. As soon as this has been done and we have supplied our model with a suit- able base, we shall be able to look at it and almost see the old coach rocking its adven- turous way over the treacherous road be- tween San Diego and Julian in California. In order to simplify the construction as much as possible, three blueprints containing full size drawings of all the parts have been prepared. They can be obtained by sending twenty-five cents for Blueprints Nos. 115, 116, and 117 (see page 111). BODY. Platforms: Brads can be used as pins in assembling the hinges. Support the front with 44 by \%-in. leather straps laced through triangles attached to the foot irons and the strips under the ends of the seats. Support the rear platform with cheap \-in. watch chains, which can be pur- chased in any ten-cent store. S-hooks bent from wire fasten the upper and lower ends to the eyes. The left-over pieces of chain serve as the stay chains which hang from the front axle and doubletree hooks. The suspension straps are l by 34 in. and are threaded through the bracket clevises until there are eight thick- nesses with enough slack to hold the bottom of the body sides 5 in. above the ground line. Drive brads through the straps, clinching them under- neath to hold the straps tightly together. Four clips placed in the rabbets on the underside of the body clasp the straps, and brads serve as. retaining pins. To get both straps the same length, stretch the first one tightly on a board, place nails to hold the ends, and By EDWIN M. LOVE To MEET the almost unanimous wishes of those readers who have written about our new hobby of stagecoach model making, the next model will be a covered wagon. After a long search, Mr. Love found a well- preserved prairie schooner stored away in the Pony Express Museum at Pasadena, Calif. He has made drawings and is building a model. When it is completed, it will be presented to the readers of Poputar ScreNcE MonruHLy. wind the second strap directly above it. Sashes: Make the frames of thin card- board, use celluloid for the panes, which are glued on the inside, and paint them black outside and red inside. Rub Irons: These are made of card- board, are 34 in. long, and are glued to the under and outer reach corners where the front wheels, in swiveling around, would rub. Similar plates protect the straps. On the forward panel of the body three irons are nailed. These can be cut with a small cold chisel, the bars being filed half round outside and bent so as to conform to the curve of the coach body. An attractive mounting for the stagecoach can be made out of a 10 by 1744 in. piece of plywood. Note the tongue placed under the carriage. ( ) LD coaches were always decorated in brilliant colors. The Diamond Tally-Ho had a cardinal red body and a yellow carriage ornamented with black striping. PAINTING. Body: Glue twelve cardboard strips on the roof (for cleats) and give the body three coats of cardinal red, using four-hour enamel and a flat 34-in. lettering brush. Strain the paint through cloth and dust the body with a brush before each coat. Allow the third outside coat to dry thoroughly and sand lightly with split 6-0 sandpaper wetted with water. Wipe the surface clean with a damp cloth, let dry, dust, and apply the last coat of strained paint. Paint the title space and panel bar bevels black. Lay out the scroll orna- ment design on paper, rub the back of the paper with a lead pencil, and transfer the design to the body. Mix a few drops of clear four-hour varnish with metal leaf gold powder and paint in the design, using a fine round brush. Do not try to use the gilding too thin, for, over the gloss of the red, it may tend to draw away. When dry, outline the design with black. Some may find it easier to use India ink applied with a small round- pointed speed-ball pen instead of paint applied with a brush. Be careful to center the title lengthwise in its space (not forgetting the period, which was always used with titles in olden days), and show a little wider mar- gin at the bottom than at the top. Inside each panel paint %¢- in. gold stripes placed so as to be 3% in. from the bars. Carriage: Dilute the yellow enamel with turpentine and carefully pour it on, catching the paint in a broad, shallow, clean pan. Two or three coats can be given as fast as they get tacky. Stroke off the excess with a brush. Enamel the wheels in the same manner and stroke the felloes and hubs. The hubs can be thrust on nails and the nails driven into a wall while the enamel is drying. Striping: Rub a little of the gloss off with split 6-0 sand- paper, sketch the stripes with a pencil, and paint them black with a small brush, making ee nnn noe al SER A ER EE abit La BR cnt aan

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em ea BTN gl eee Ee a ee e moll 1 pore eh petsm? dines kr as Wn ' | i} ee ee _ Above: The sections that make up the center seat are hinged by gluing a strip of cloth across the top before the upholstery is applied. Right: The completed seat. lines % in. wide. A round-pointed speed- ball pen charged with India ink may be substituted for the brush, if desired. Wheel spokes, hubs, doubletree hounds, and other parts having straight stripes or stripes parallel to the edge are decorated by lashing a ruling pen to a thin strip of wood so that its tapered end will be a little below the point. A wooden wedge for clearance adjustment should te thrust between the pen and the wood. Use ink in the pen, with a wooden strip bearing against the part, thus acting as a guide. Tires, hub bands, and singletree fer- rules are painted black. When the paint is dry, screw on the wheels and mount the body permanently. RAILING: For this, tinned radio bus wire may be used. Make a form by driving nails into a board for use in hold- ing the pieces for soldering. The hand- grips, which incline 45 degrees, can be held with a pair of pliers while being sol- dered. File points on the posts and force them into holes drilled into the roof for the purpose. The seat-rail rods enter sockets in both the seat and body, having the upper rod inside the brace, and the other rod outside. LEATHER: Imitation leather may be used in all cases. The writer used a lady’s bag that had been dis- Lain my rd carded. Cut paper pat- terns, allowing ample material to fold around the straps and chains. The lower edges are ENTIRE fastened to the plat- thes ay form and seat edges RED with % in. wide, No. 14 gage metal straps held in place with small brads. A _ boot cover, wide enough to lap 3 in. over the . © Eds sides, hangs from a wire ae rod supported by eyes under the top at the back of the body. The driver’s seat and back cushions can be made by covering lino- leum blocks with CARPET leather. UPHOLSTERY. WOODEN FRAME Seat Backs: Strips of VELVET ASG} eg POPULAR SCIENCE MONTHLY ¥\-in. linoleum, 24% in. wide and long enough to fit, form the 16 vertical half rolls which are gathered in 4% in. below the upper edges. Trim the linoleum by cutting the back. The dark green velvet is held in place over the rolls with shellac. Press the cloth into the folds with the back of a knife blade, beginning at the center and working toward the ends, holding the finished fold tightly until the one directly ahead is made. Paste the edges smoothly over the backs. The backs are glued in place after the seats have been fitted. Carpet: Velvet is used as carpet and is glued to the entire floor of the body. Seats: Fit a cardboard pattern 2% in. wide between the sides at each end, and to these shapes make the 34-in. thick wooden seats. Square lines across the tops, making divisions like those on the backs, and continue them down across the front. Cut saw kerfs % in. deep on these lines, carve the rolls, and cover the seat with velvet. In placing the seats, make the front % in. higher than the back and tack a small wooden cleat under each seat to prevent it from sliding forward. Sides: Fit linoleum pieces having two horizontal 5¢-in. wide half rolls under the large windows and another % in. wide, which curves parallel to the window sills. These are continued across the doors. The remaining space below the windows is covered with muslin and painted red. Center Seat: The drawing and photo- graphs show the general construction of =, _NELVET ARM PADS /lt6* ie" | “ ty, % 1% “ 1% | |7 Pe Bie DOOR 2%4— 5 > erst ww OFFSET SGIMP > : "SILL ?\WOOD sa THICK f 5) I ole WIDE CENTER’SEAT GREEN VELVET OVER LINOLEUM CLEATS (CARDBOARD) = Section through the body showing ing the upholstery plan. Full size draw- ings are included in blueprints Nos. 115, 116, and 117 (see page 111). APRIL, 1930 this seat. The end sections, which rest on the door sills, fold back to admit passen- gers to other seats. The cloth hinges are glued on the top before adding the cush- ions. Nail the center legs through the body floor, after placing the seat so that the rear edge is 34 in. from the rear edge of the doors. MOUNTING: The model base is made from a piece of 34-in. five-ply stock, 10 by 17% in. Nail a 3% by 3% in. mold- ing on the edge to hide the plies. Set the nails and fill the holes with plastic wood. Finish with four coats of black enamel, well rubbed with pumice stone and water. Stand the model on a board, with the wheels centering on the width and the length, and clamp them in place with leather-lined metal clasps screwed to the base. Lay the tongue under the model. A few points as to the finishing touches: See that the doors fit flush, that the boot CARVED LINOLEUM COVERED WITH VELVET + LINOLEUM FORM COVERED WITH VELVET ) 15° Construction of the upholstered end and fold- ing center seats and plan of side upholstering. buckles are neatly clinched, and that the seat cushions are in their proper places. Adjust the wheels so that the under spokes are vertical, and the front and back wheels are parallel to the base sides. The tongue can be placed, head for- ward, under the carriage and can be per- manently fastened to the plywood base with small metal clasps similar to those that are used to hold the wheels in place; then the tongue will not be lost. In order to be sure that the painting on the model is perfect, go over the entire body and car- riage and remove any unevenness that may be present in the striping or the lettering and re- touch these spots with a small artist’s brush. Be » sure that the windows libs are free from dirt and paint. LEATHER COVERED Ke All of the carriage build- a ing terms which are not self-explanatory are clearly marked on Blueprints Nos. 115, 116, and 117, which ~contain full size drawings of all of the parts. In mak- such a_ complicated model as this, full size drawings are essential. CARVED LINOLEUM At

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130 en- are sh- he lat ige ok ld- et tic ck ne he he th he pl. ot ee 7} Ss © tO OD —w & 1 US OD Apri, 1930 POPULAR SCIENCE MONTHLY COS — Goes with the Doctor on His Midnight 79 Mission - + - Roars into Icy Arctic Wastes with Byrd - - Stands Guard by Seething Cauldrons of Steel - - AR down in the frozen antarctic a plane carrying a little band of zeal- ous scientists roars into the air for a dash to the pole. Along their course mountains of glistening ice and snow rear a dazzling and dan- gerous barrier. But science, by perfecting the plane, has put them in the air—has provided the most delicate and sensi- tive of instruments to keep them safely on their way—mak- ing possible the most accurate of surveys. Without the most accurate of instruments, this little band of pio- neers, in such blind- ing wastes of snow, might easily loose direction, thereby failing in the survey which means so much to those who will come after. They watch, climb, pers skim the highest peaks, and return to their base with the first aerial survey ever made of the wild antarctic. And the special surveying Aneroid Barom- eter they use in this pioneer observation is provided by Teos. OTHING man has made is so delicately adjusted, so sensitive as man himself. He is peculiarly dependent upon heat— both the heat of the sun and heat he gener- ates within himself. His temperature must not vary more than a few degrees from the normal—98.6 degrees F. ven a slight variation may foretell serious danger. Now you can see why the doctor’s first step in diagnosis is to take the sick man’s temperature. He thrusts a little thermom- eter under the tongue, and waits till it regis- ters the patient’s temperature. Without the thermometer he could not prescribe intelli- gently. Remember that a variation in tem- perature from the normal of only one de- gree is a danger signal; two degrees is a oe of illness that may be serious, even atal. Life and death may depend on the cor- rectness of the little instrument that the physician places under your tongue. If it is wrong. . . ! On these highly accurate thermometers used by the doctor is engraved the name fyeos . by Frank M. Herbert EFORE Pasteur discovered the deadli- ness of bacteria, babies died with vari- ous unclassified and somewhat mysterious ills. They died because the cow’s milk they fed upon was swarming with invisible dis- ease germs. Pasteur showed that heat killed the germs and made the milk safe to drink. That is why milk is “pasteurized,” or in other words heated up to a certain point. The tempera- ture to which the milk is heated must be carefully maintained. [f it is too low the germs are not killed; if it is too high the milk is cooked, and hard to digest. Thousands of gal- lons of milk flow through a heater in the modern dairy. The temperature rarely varies even a fraction from the critical degree. It is automatically controlled by a wonderfully accurate instrument which regulates the amount of steam supplied to the heater. On the face of that instrument stands the name “‘fyeos Temperature Regulator.” iv ONLY one bottle of homemade catsup out of twelve spoils, the housewife has a good average. But a canning factory might face ruin if even one per cent of its products went bad. Every can of corn on the grocer’s shelves must be as good as every other one. Vegetables must be cooked when they are canned. Most of them contain indigestible raw starch. So, the canner must cook his corn. A metal rod dips into the kettle. It is like your finger—that rod; it feels how hot is the corn. With the slight- est rise or drop in temperature it signals back to a valve on a steam- ipe. “Turn off the steam,” it says if the corn is too hot; or “more heat,” if the tem- rature falls. And the regu- ator responds instantly by moving a valve. No tired workman is asked to watch the temperature at 5:30 P.M.. when he is thinking of going home. The regulator is never tired. It never allows the temperature to vary. The cans in which the vegetables are contained are sterilized. In other words, all the germs killed by heat. Without ther- mometers the canner would not know whether the temperature is high enough to kill all germs. Some of the cans would spoil on the shelves of the retailer. On the heat- measuring de- vices the can- ners use is the name Tycos . VERY- THING made of rub- ing from an ber is vulcanized — ev automobile tire to an elastic band. When rubber is vulcanized it is mixed with sul- phur or other chemicals. The effect is The properties of the rubber magical,

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eee Sines ee * . a ee ne oe BART : 80 become wonderfully changed. The result desired depends on the amount of chemicals added and on the time and_ temperature control. Without heat the vulcanizing sub- stances could not be digested by the rubber. But the heat must be regulated. Every vulcanizing apparatus must have its ther- mometer and temperature regulator. With- out the ther- mometer there would be no rub- ber industry — no insulated submarine cables, no auto mobile tires, no vulcanite uten- sils, no electric insulators made of rubber. In the great rubber factories, where heat regu- lation is so vital, Recording Ther- mometers and Regulators are used that bear the name Tyeoe. HERE are almost as many kinds of steels as there are kinds of wood. Add a little chromium, or nickel, or tungsen, or vanadium—a mere pinch of any one of a dozen different ele- ments — and you produce an alloy-steel with perhaps valuable properties. But without “heat treatment,” as it is called, there would be no modern science of metallurgy, no inexpensive auto- mobile. It is heat treatment that makes it possible to produce an alloy-steel axle from which an eighty-ton locomotive can be suspended; to pull a valve-stem out like rubber in a testing machine; to obtain a gear with a surface so glassy-hard that a microscope must be used to detect the wear to which it has been subjected after running ten thousand miles; to manufac- ture a Tachooed or a steering-knuckle that can be operated a hundred thousand times without weakening. But heat treatment implies careful heat measurement. The furnace in which the parts of an automobile are heated must be WN IQy | | watched. And watched they are—by a man who never sees them. He sits in front of a series of electrical temperature recorders, called Recording Pyrometers, perhaps hun- dreds of feet from the furnaces. Fach re- corder is connected with its furnace. If the temperature of a furnace rises or falls ever so little the man at the temperature-control boards knows it. He warns the man in charge of the furnace by flashing an electric POPULAR SCIENCE MONTHLY light. On the Pyrometers depends the ulti- mate quality of the parts that compose an automobile. Every great automobile fac- tory has its temperature control room. On the pyrometers that check the furnaces you will find the name Feos. | THE glass fac- tory, the steel plant, the copper smelter, inevery plant where furnaces are installed so hot that metal or clay becomes as liquid as water “merece \\ , when subjected to their terrific heat, you will see a man now and then setting up a little in- strument on a tripod and looking through a telescope. He is finding out how hot the furnace is. He cannot use any ordinary heat-measurer; it would melt away like butter on a stove. His instrument is the Féry radiation py- rometer. When you understand the prin- ciple of its operation you think of the time when you burnt your name on a piece of wood with a lens. The instrument focuses the heat from a furnace or from a white- hot body. Instead of a lens it has a con- cave mirror, which operates in the same way. When the heat rays strike the mirror they are concentrated on what is known as a thermo-couple. Now the thermo- couple consists merely of two different metals joined together. When they are heated an electric current is generated; the hotter the junction, the more Canadian Plant: eos Building, Toronto SHORT & MASON, Ltd. Manufacturing Distributors in Great Britain Iaylor /nstrument Companies Main Officeand Factory: ROCHESTER, N.Y., U.S.A. 2 E~ SIXTH ~ SENSE ~ Tycos Temperature [Instruments DICATING - RECORDING ~ CONTROLLING APRIL, 1930 powerful will be the current. It is easy to see that the current has only to be meas. ured in order to determine the heat concentrated by the mirror on the thermo. couple. That heat may be as high as 3600 degrees F.—-hotter than white-hot molten steel. Until the Féry radiation pyrometer was invented high industrial temperatures could be only approximately measured. On the Féry pyrometers sold in this country appears the name feos. MAGAZINE of smokeless powder or dynamite is absolutely unsafe without thermometers to detect the slightest rise in internal temperature. A cold-storage plant would be a commercial failure without tem- perature control. A wholesale baker of bread would be helpless without thermometers to control his ovens, Wherever there is an asphalt-melting tank,'a tar and oil still, an ink fac- tory, a paint-making plant, wherever, in a word, there is an_ industrial process, there you will find a tem- perature-measuring instrument of some kind. And upon that instrument you will see the name fyeos. |= original firm of Kendall & Taylor made only half a dozen different kinds of thermometers in 1851, and those only for household use. But the Zr Instru- ment Companies of today, makers of feos Instruments,—the largest firm of its kind in the world—produce not only thousands of different styles of thermom- eters, but compasses, hydrometers, hy- grometers, vacuum-gauges, meteorological instruments, aeronautic navigating devices, and blood-pressure instruments. Wherever a pressure indicator or a heat-measurer is used you are almost sure to find that it bears the name fycos. st Fr INDUSTRY _~ Th AS oes & 4A oe ee

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1930 sy to 1€as- i\eat rmo- ten eter ures nutry r or 10ut e in lant em- aker out ens, ting fac- ver, rial em- yme lor ids aly ru- of ily y- cal es, er ae | iy? We

ApriL, 1930 POPULAR SCIENCE MONTHLY 81 A Quaint Old Candle Lantern How to Make a Copy in Tin and Glass of a Decorative Early American Light By EDWARD THATCHER OPIED from a design of Colonial days, the quaint candle lantern illustrated will give the beginner in decorative metal work an op- portunity to practice the soldering oper- ations described in the preceding article of this series (P.S.M., Mar. ’30, p. 82). A lantern of this type may be made three-, six-, or eight-sided and of brass or copper, but the beginner is advised to use sheet tin. This is sold in sheets about 20 by 40 in., although by opening out bright, clean, empty tin cans the ma- terial can be obtained for nothing. The top of the lantern may be made from the bottom and part of the sides of a tin can. The ring or handle is a strip of tin, each long edge of which is turned or folded back. It is held to the top by a T-shaped piece of doubled wire, the ends of which are curled over with the pliers. A removable candle socket is provided in the model shown just as in the old lan- terns, but an electric light socket may be mounted in its place. The model is painted with jade green lacquer except for the inner part of the sliding back, which is left bright. . To make the lantern, scribe a line 114 in. up from the bottom of a tin can 3 in. in diameter and cut the can down to this line as at A in the drawings below by holding the open end toward you and cutting in a spiral fashion, from right to left. Next cut two 534-in. squares of tin for B and D. With a wooden mallet bend down the flanges over the square end of a block of wood. In one piece cut a cir- cular opening 3 in. in diameter; this may be done by placing the piece on the end grain of a flat block of wood and using a sharp, narrow chisel. Form the four angular pieces C for the sides from flat strips of tin 1 in. wide and 734 in. long. If you have no folder, you may easily make a wooden substitute. Note that one of these clamping pieces is planed off at a slight angle so that the tin may be bent down at slightly more than a right angle; it will spring back to a right angle naturally. Two U-shaped channels of tin for the back of the lantern, which slides up and down, are formed in the same way; then each strip is placed on an anvil, an extra length of tin is placed in the angle, and a mallet used to hammer the piece to the channel shape. Take up part A again, scribe a line 1% in. up from the bottom and parallel to it, and an- other line on the inside of the can 1% in. up from the bottom. Blunt the point of a small cen- ter punch, lay the cut can on its side on a block of wood, and work- ing from the inside drive up a number of bosses on the 1%-in. line. These bosses keep the can from sliding too far inside piece B. The large ventilating holes are made by placing the cut can on a thick strip of lead supported on a solid steel anvil form, the whole being slipped inside the can when it is being punched or cut with a sharp, small chisel. Also make a number of snips 4

: oa at] SECTION OF ' N| LANTERN ' FRAME : - ‘ - -- “le 8 ‘ H 4 ye 1] SUGGESTION rs) ‘|FOR VENTILATOR } j|TOPIF CANIS | ra iJ NOT USED O

An assembly drawing of the tin candle lan- tern, details and patterns of the top and bot- tom members and socket, and diagrams illustrating three of the chief operations.

Using a homemade wood- en folder and a block of wood to bend the an- gular sidepieces. The completed tin lan- tern is shown at the left: in. apart around the side of the can, cut- ting to the “1%-in. line. Push the’ can through B, bend over the lugs, and soft solder them. the corner pieces C, six short angular pieces of copper H must be made and ‘soldered in place to hold the glass. <A flat strip of wood slightly thicker than the glass is placed be- tween each piece H and the side of B or D while the soldering is being done. If the lantern is for a candle, a socket E should now be shaped over an anvil % in. in diameter. Notice that this piece is formed with two lugs at the base, which fit into chiseled slots in the strip of tin F under the socket. A short strip of tin G is soldered at each end to piece D in such a way that the tongue of tin fastened to the socket may slip under it. If the lantern is to be used with an electric light, a flat-bottomed socket may be bolted to the bottom. Now carefully solder corner pieces C and the two slides for the back. Cut six lengths of %%-in. galvanized wire to form the guards and solder as shown, using pure muriatic acid as a flux. Next, fasten handle J with %-in. wire K pass- ing through J, A, and a tin washer J. Single-thick window glass, either clear or stained, is cut to fit the lantern, and is put in place by bending out the unsol- dered portions of the angular pieces H, which are then pressed back against the glass in order to hold it in place. An article by Mr. Thatcher dealing with the correct methods of doing hard soldering and light brazing is scheduled for early publication. Before soldering * - aR Se ee OF seers oe oe : F cere are _ a en ae arr ae ance eee ee

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Above: Mr. Neth, designer and buiuer, with his graceful modified Ferdinand Schulz model. ESIDES being a delightful hobby and pastime, the construction and flying of model gliders present an opportunity to learn the principles of airplane construction and the theory of flight. . What could be a more instructive proj- ect for the embryo aviator than building a model of the famous motorless plane in which Ferdinand Schulz broke a world’s record by staying aloft for over fourteen hours? Alfred Neth, of Pasadena, Calif., has made a special study of that remarkable glider and, with only a few minor modifications, has reproduced it in the form of the flying scale model illus- trated. The model has the characteristic long narrow wings and the streamlined fuselage of Schulz’s glider. One slight addition is a shock absorbing music wire landing gear which protects the glider if it makes any heavy landings. The landing gear also serves as a means of bringing the center of gravity well below the center of the wing—an advantage in all airplane construction. With the exception of a few small parts, such as the landing gear and wing support, the construction is of balsa wood through- out. The longerons and all of the cross frames are made from % in. square stock. The forward ends of the longerons can be bent either by steaming them or care- fully heating them over a small flame. To insure accurate work it will be an advantage to draw the outlines of the side frames and wings on a board and then assemble the parts right over the drawing. The rounded nose piece is cemented to the nose plate in such a way that the grain of one is at right angles to the grain of the other. This is done to obtain added strength. In assembling the tail structure, a 4¢-in. panel of balsa is placed on the top and also on each side, and the bottom is pro- vided with a %-in. piece which receives the wire tail skid. Assemble the wing in dry weather and keep it out of the direct glare of the sun until it is completed. Every precaution must be taken to keep it from warping. The completed wing should only weigh 11% oz. for all of its 62-in. spread. POPULAR SCIENCE MONTHLY APRIL, 1930 Building a Model Glider A Miniature Motorless Plane Like That Piloted by Schulz Below: The fuselage is well braced and strut- ted to insure strength and remove the danger of twisting and warping in hard usage. Gluing on the rice paper requires con- siderable patience. The glue should be applied lightly with the tip of a finger to one complete side at a time. Stretch the paper as tightly as possible; and when both sides are covered and thoroughly dry, apply a coat of wing dope. When this, in turn, has dried, give it another coat so that the finished job will be drum-tight. Do the drying with the wing laid flat, bottom side down, on a flat surface. If one end or the other has a tendency to lift up, hold it in place with a few small weights. Maple dowels, % in. in thickness, are secured to the spars of one side and fit into aluminum tubes fastened to the other half. These dowels pass through holes in an aluminum plate (see illustration on page 84) placed in the center of the By HI SIBLEY balsa wing block, which, in turn, is se- cured to the fuselage by two rubber bands attached to two hooks. Since these hooks straddle the curved top of the fuselage, adjustment of the wing for best per- formance is a simple matter. The wing should tilt upward at about 4 degrees to the direction of flight. This is accomplished by slightly tapering the wing block mak- ing allowance, of course, for the taper of the top portion of the fuselage. Stiffness is obtained in the rudder construction by the use of stream- lined ribs. This design also removes the danger that the rudder will warp under the sun’s heat. The stabilizer is built with a re- verse camber which tends to hold the tail down in a slow glide, thus preventing a nose dive. Not infrequently it is found that model gliders have a tendency to nose into the wind at the wrong time. To over- come this, a steering adjustment has been incorporated in this design. It consists of an aluminum plate having five or six holes in the forward end to receive a wire that is cemented to the front end of the rudder and stabilizer assembly; and there is a hole in the rear to receive a pivot. In trying out the glider, select a group of gently rolling hills or sand dunes along the beach. The wing and_ rudder- stabilizer unit will have to be adjusted as necessary to obtain the best results. Ex- cellent results were obtained by Mr. Neth in flying the glider over sand. It gained altitude quickly and then settled down et Xe . 3 TRAILING EDGE LEADING EDGE Ng x Ya" SO. Y6" SHEET , “By RUBBER HOOKS BALSA ; \ gO 4g CURVED TOP FORMERS 5 Lug - | 44S +h 24 “i be ws ie ee | 2"wiDE 134° WIDE An i ved | | 29 yf 27" FUSELAGE LENGTH oe Dimensions of the model. With the exception of the music wire landing gear and a few small metal parts the construction is balsa wood throughout. The wing is provided with a dihedral of 1% in.

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MONTHLY POPULAR SCIENCE Wheels on the ROAD ... Fhats SAFETY Riders on the SEAT ... thats COM FORT ie e nds - P Aprit, 1930 age, Bouncing wheels are a constant danger eis | Bouncing seats are a constant discomfort OUDAI wOO-oVvE~ rit — 5%: acing —_ Enjoy the Houdaille Smooth Ride over Rough Roads at any speed. HOUDAILLE Rough roads are the proving grounds of Comfort and Safety. . t SHOCK ABSORBER . It will be your standard of comparison. See the Houdaille distributor in your town or write for booklet. i PIONEERS AND WORLD'S LARGEST PRODUCERS OF HYDRAULIC DOUBLE ACTING SHOCK ABSORBERS

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EASE EPI NST Re Se Gah Aa eaeeneare nr ee ey a aaa Ae yet Sa peer Gee Oe ROO ey ae REE To eae eR one | | i] i} ie ie | $ ¥ erable tie He ae er ee + aPee eee 84 ( AWMINUM > — BALSA — =4%" +f RUBBER HOOKS Shape and dimensions of the wing block. Note the hooks at each end to receive the rubber. THREAD - BOUND AND CEMENTED EXAGGERATED DRAW- ING TO SHOW STREAM LINED RIBS FOR POPULAR SCIENCE MONTHLY into a long, graceful glide to the earth. In flying any type of glider, always pick a locality that presents many sources of rising air currents; a rocky valley or a sandy beach is probably the best. The glider then will soar from one rising cur- rent to the next, gaining altitude each time it passes over an upward eddy. To launch the glider, grasp it lightly just back of the wings and thrust it for- ward with an easy motion of the arm. Do not try to force the glid- er by launching it with too swift a motion. The hand should serve as little more WOUND WITH THREAD AND CEMENTED FOR AXLE NUTS. LANDING GEAR Sy DETAIL (MAGNIFIED) ALUMINUM TAIL PLATE WITH HOLES FOR RUDDER ADJUSTMENT STABILIZER _HAS 4" REVERSE STIFFNESS. than a platform for launch- ALL 16 BALSA ing. o If the glider does not perform as it should, an adjustment of the wing either backward or forward or of the stabilizer to the right or to the left will probably remedy the trouble. CAMBER | ” 46 PIECES With the coming of spring aes bt de AYOUT BETWEEN. eat pe ia ~|_IN " SQUARES Ye RIBS RIBS and warmer weather, airplane sot anne SPACED 2/5 model activities can again be ar. " — | carried on out of doors. =, ra — A Plans for eight flying models ; are included in the list of blue- yg prints on page 111. These FOR DOWELS Construction of the music wire landing gear rudder and stab- ilizer unit wing and wing tip; and dimensions of the wing ribs. blueprints contain full size drawings of the planes with all of the necessary dimensions and important details of con- struction. An article by Mr. Sibley dealing with the construction of a swift pursuit model is scheduled for early publication. APRIL, 1930 The model gains altitude quickly, soars on rising air currents, and then glides gracefully. COMING FEATURES Hard Soldering and Brazing How to Make a Hepplewhite Card Table Testing Brasses and Bronzes * Building a Double Workbench for the Home Workshop Unique Forms of Trout Flies and | How to Make Them Hanging Curtain Rods Correctly Making a Hunting Knife from an | Old File Rubber Ball Saves Sliding Door from Slamming WHEN the easily constructed device shown below is installed on the jamb of a sliding door, it is impossible for any- one to slam the door closed and perhaps ruin the catch and spring jamb. The device consists of a small soft rubber ball attached to a steel arm, which in turn is fas- tened to the jamb of the door in such a way as'to rest against the inside of the jamb when the door is open. The arm is pivoted at the wall fastening so that it can be lifted free of the jamb and allow the door to be closed. The gooseneck piece acts as a handle and also serves to keep the ball against the jamb. If anyone shoves the door shut without first holding the ball away from the jamb, the rubber ball will take the shock and save the catch.—R. H. DAUTERICK. SWINGING ARM The ball is fastened to a freely swinging bracket. How to Build a ne Speier fed horses for use in supporting work are an indispensable part of the home workshop equipment. Makeshifts are bound to give difficulty in even the simplest of jobs and should therefore be avoided. The tops (B) of the horses shown can be made from spruce, fir, or similar wood. Cut bevels to re- ceive the eight legs, being sure that they will give the neces- sary flare to the legs, which must slant outward in such a way as to prevent any possibility of tipping. The legs, cut from l-in. stock, are 6 in. wide at the top and 4 in. wide at the bottom. Cut them slightly long and nail them in the re- cesses chiseled in the top. Fit the legs carefully, being sure to obtain the correct amount of flare. After the legs have been placed, plane the Sturdy Sawhorse tops of them flush with the top of the horse, then turn the horse upside down as shown at C and measure the height of each leg from the floor. In this way any de- viation in the flare of the legs will be allowed for automatically. The two end pieces (A) are cut from l-in. stock and fitted in place after the legs have been at- tached. If the horses are to be used in the construction of fine furniture or if fin- ished work is to be rested on these sup- ports, wind thick cleth or felt around pieces of 34 in. square lumber and ® brad two of these to the top of each horse as shown in D. These also serve as stops when the legs of a chair are rested on the tops of the horses, as in the upholstering of chairs and benches.—C. A. K. The wide flare of the legs insure stability.

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the 1 as ach de- be om the at- are the ine fin- up- ick ind ind ese ich in so len air che es, nd Aprit, 1930 POPULAR SCIENCE MONTHLY . | 85 with inferior tubes!" Says F. A.D. ANDREA, President of F. A.D. ANDREA, INC. “FADA RADIO” “WE test all our sets with RCA Radiotrons and recommend the use of RCA Radiotrons for Fada Vibra-Control Radio. RCA Radiotron quality and engi- neering precision assure the maximum per- formance built into every Fada set. They. are the only safeguard against troubles caused by faulty tube construction. Take no chances with inferior vacuum tubes. To get maximum enjoyment from Fada Vibra-Control Radio use long-lived RCA Radiotrons throughout for both initial equipment and yearly replacement.” RADIO ENGINEERS ADVISE: Replace all the vacuum tubes in your radio set with RCA Radiotrons at least once a year. This is the only sure way to maintain good performance and mini- mize disagreeable noises and other troubles caused Look for the red and by inferior tubes. RCA Radiotrons will give you the black carton and thefa- maximum in selectivity, sensitivity and tone quality. nous RCA trade-mark Old tubes may impair the performance of the new RCA RADIOTRON CO.,INC.,. HARRISON,N. J, RCA Radiotron THE HEART OF YOUR RADIO SET @ This seal on an advertisement ir POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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~~ ES PR ELIT OL See 2 mee > OF 2 a tre I et tae —— Sides ete 4 i ia , . i) i 8 } i! 3 fi oe a. RMT we LAR ~ . o v hae Bie QW Reece “eda 86 POPULAR SCIENCE MONTHLY APRIL, 1930 Helpful Ideas for the Car Owner F ALL roads were level and smooth, the problem of jacking up a front or back wheel to change tires would always be simple. Unfortunately, however, there are many times when the normal safe place for a tire change, off the paved portion of the road, presents unexpected difficulties. There may be a deep rut exactly where the jack should be placed, or the road may slope in such a way that the car is likely to roll off the jack. A pair of wood blocks shaped as shown in Fig. 1 will prove useful in such emergencies. One will serve as a chock for the car on a hill. Two, four, six, or even eight inches can be added to the height of the jack to reach up from a hollow depending on how the blocks are piled. The two blocks bolted together will support the front axle with both wheels off the ground when adjusting, greasing, and so on. For a large car or truck the blocks should measure approximately eight by twelve inches, with the thick- ness four inches at one end and two inches at the other. WINDSHIELD WIPER DRILL HOLE IN GLASS OUTSIDE OF WINDSHIELD Fig. 2. This suggests a practical way of keeping the windshield wiper out of the line of vision. Spring Holds Jack THE ratchet type auto jack always seems to work out to its full length in the tool kit, causing a delay while it is racked back to its telescoped position. Figure 3 shows a way to overcome this trouble. A light spring is attached at one end to the head of the jack and at the other end to the toe. Wiper Arm Holder Many types of windshield wipers cause trouble when not in use by slipping down into the line of vision. A simple and positive wiper holder is shown in Fig. 2. Drill a one-eighth-inch hole Fig. 1. Jacking up a car on uneven or rutted ground is easy if you have these blocks to put the jack on and chock the car. At right are shown the blocks ready to use if both wheels are to be jacked at one time. AS A CHOCK BLOCKS BOLTED TOGETHER FOR A STAND FOR CENTER OF FRONT AXLE the compression stroke. Screw in test device and work the pump handle up and down. If the exhaust valves leak, a hissing sound can be heard from the exhaust pipe. A leaky inlet valve will produce a hissing at the carburetor air intake, and if either the wrist pin or con- necting rod bearings are loose there will be a slight knock each time the direc- tion of motion of the pump plunger is re- versed. The noise produced by a loose bearing will be much more distinct if the test is made while the motor is hot after a trip. A cold motor may not give any loose bearing noise because of the congealed oil. Simple Test for Leaks LEAKS in the cool- through the glass and fit a short screw and nut so that the end of the screw will project just enough to act as a retaining pin. While this arrangement necessi- tates reaching outside the windshield in closed cars, it is ideal, because of its neat appearance, on sport roadsters. Pump Tests Loose Bearings THE shell from a discarded spark plug, a brass nipple, and an old tire pump can be made up into a connecting rod and wrist pin bearing tester as shown in Fig. 4. The nipple should be screwed or soldered into the spark plug shell and into the end of the pump. The plunger of the pump should be removed and fitted with an extra washer in reversed position so that it will be air-tight when moved in either direction. To use the device, remove the spark plug from one cylinder and turn the crank shaft till the piston is at the top of Fig. 3 above; spring keeps auto jack from working out to full length in tool kit. Fig. 4, right, shows homemade device for testing of bearings. POPULAR SCIENCE MONTHLY awards ' each month a prize of $10, in addition to regular space rates, for the best idea sent in for motorists. This month’s prize goes to Charles H. Willey, West Concord, N. H., for his suggestion for handy jack blocks for use in changing tires (shown in Figure 1, top of page). ing system are some- times only apparent when the engine is operating, and the circulating water is hot. Such leaks are difficult to find and TO TIRE PUMP VALVE STEM CORD RUBBER COVER =X RADIATOR FILLER OPENING A INNER TUBE RADIATOR . OVERFLOW PIPE . [yi! RUBBER FLAP » » BOUND WITH CORK IN CORD OVERFLOW PIPE Fig. 5. Leaks in the cooling system are easily found when pressure is applied as shown here. repair. The smallest leak, however, can be detected at once by applying air pressure to the cooling system. This may be done by using part of an old inner tube and a piece of cork. Use the cork to plug the overflow pipe and cut a circle of rubber from the inner tube with the valve at the center. Remove the filler cap and bind the section of the inner tube over the opening as shown in Fig. 5. Pressure is then applied with a tire pump. Only a few strokes are re- quired. Be very careful not to apply too much pressure to avoid damaging the radiator. The radiator of an automobile is not designed to withstand pressure. Too much may open up a seam or bulge out the side of the upper or lower water tanks. AP!

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: ‘ool- me- pine r is and LAP ITH ily re. can air ‘his old the it a ith the the 1 in ha re- too the bile ire. Ige ter Aprit, 1930 POPULAR ae PRO Here are found in ood-Fiber Insulating Boar SCIENCE MONTHLY BuIL ADVANTAGES IF YOU want strength and durability built into your home—if you want efficient protection against heat and cold, use an insulation material that has great structural. strength and high insulating efficiency. In a recent laboratory test the four best known insulating boards were tested for strength . . . and Insulite proved to be 14% stronger than any. And not only is Insulite stronger, but—full % inch thick—another laboratory test proves it 1214 % more efficient insulation than ordinary ‘%e inch insulating boards. And here are additional advantages—Insulite, a strong, all wood-fiber board, is chemically treated to resist moisture, and is not subject to deterioration. Used as sheathing, it has several times the bracing strength of lumber horizontally applied, and as a plaster base it grips plaster with twice the strength of wood lath. If you are a prospective builder, ask your architect, con- tractor, or lumber dealer about the many advantages of Insulite. Write for our free booklet, “Increasing Home Enjoyment,” and a sample of Insulite to test. Gnsulate with I NS | JLITE 14 7 STRONGER PECTIVE THE INSULITE EFFICIENCY TEST FULL % INCH THICK MEANS i MORE 2 / EFFICIENT O INSULATION THAN ORDINARY %e INSULATING BOARDS MAKE THESE TWO TESTS Prove Insulite’s greater strength..... Drive a nail a half inch in from the edge and through a board of Insulite. Loop a strong cord around the nail and with hand scales, see how much greater pull is required to tear the nail through Insulite than through any other insulation boards similarly tested. Prove Insulite’s greater efficiency ..... Place a cube of ice on a piece of Insulite over an automatic electric iron set at hot. See how long it takes the heat to penetrate the Insulite and melt the ice. Make the same test with any other insulation boards. ‘Then we know you will use Insulite. THE INSULITE COMPANY (A Backus-Brooks Industry) 1200 Builders Exchange, Dept. 43D Minneapolis, Minnesota OFFICES IN ALL PRINCIPAL CITIES | THE INSULITE COMPANY, § 1200 Builders Exchange, Dept. 43D, ; Minneapolis, Minnesota. 1 Gentlemen: Please send me your free book, t “Increasing Home Enjoyment,” also a FREE SAMPLE of Insulite to use in these two tests. Wam Address City State. If more convenient write on margin.

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eet oes ~ wR 5 $a se —_—— 3 : : SRE Bs a6" Te ye é if ¥ a! 7 bel y z ta | 4 A ROT Se Rn Pa i Trimness, durability, seaworthiness, and ease of construction are features of the Seascoot. ITH the frame erected and the seam battens, chine logs, keel, and other parts in place, our 1514-ft. outboard motor boat Seascoot began to look like a real boat. The construction had been carried to the point described in the preceding article (P. S. M., Mar. ’30, p. 75), and the frame was ready for the planking. The lower side planks were prepared, first one side and then the other. they subdivided each frame into three sections, the first plank was fitted so that its edge came as exactly as possible to the center of the lower seam batten; that is, the one nearest the chine. In planking, it is well to remember that most of the bend is toward the bow and therefore it is far wiser to get the bow end fastened in place first and then work toward the stern. If you do not do this, you will find that it is much harder to make the bend; and it may take two or three assistants to hold the plank in place while you put in the last few screws. The way we worked it was to set the plank up in place and clamp it fast after first planing off any rough edges. In attaching a plank, it was necessary first to determine the bevel at the point where the plank came in contact with the rabbeted stem piece. This was done by holding the plank as close as possible to the stem and marking it with a pencil guided by a short length of straight wood held exactly parallel to the rabbet in the stem. The plank was then taken down, the excess wood sawed off, and the cut end smoothed with a plane. With the bevel cut, the next step was to have an assistant hold the plank in such a way that the bevel fitted snugly against the rabbet. The plank was not bent but merely held in place, the stern end being far out from the side of the boat. Two or three screws were used in fastening the plank to the stem. Then we started screwing it fast to the chine log. Placing screws every 4 in., we gradually worked toward the stern. After the plank was securely in place, we went back and screwed it to each frame, putting in about three screws between the chine and the first seam batten. While the corresponding plank on the opposite sid: was being fitted and Since - the seam battens were located so that . the chine line. POPULAR SCIENCE MONTHLY APRIL, 1930 Denuiistin: Our Seascoot Boat How to Plank and Calk the Above: Marking the bevel preparatory to cutting and fitting a plank. Right: How the lower plank is clamped prior to fitting. fastened, my coworker started to remove the excess wood on the first plank with a draw knife (a big jack plane would serve as well). The second plank was fitted in just the same way as the others, except that it was shaped to come to the center of the second seam batten. First, it was clamped up against the side of the boat, and the bevel cut; then we proceeded to run a pencil inside in such a way that the out- Planing down the lower plank, ae se it nearly flush with The edge must be true with the frames. Sides and Bottom, Build Decks, ‘and Attach the Deck Fittings By W. F. CROSBY Editor of The Rudder line of the edge of the seam batten was transferred to the inside of the plank. The plank was then removed and another line drawn at a distance of one half the width of the seam batten inside of the first. This line was used as a guide for the cut. Both edges were planed to remove any roughness and then the plank was fastened in place. The third side plank has one edge on the upper seam batten while the other edge forms the sheer. The sheer heights were then laid off on the plank after the lower edge had been fitted to the other plank and the bevel for the stem cut. The excess ma- terial was planed off later, when the boat was turned over. We started amidships with the bottom planking and laid a piece of the 34-in. stock across the boat, squared it with the keel, and then marked it with a pencil to the shape of the side on the underside of the plank. This was done to make the ends conform to the shape of the sides of the boat. The plank was then taken off and sawed close to the pencil marks. In order to keep the joint (where the bottom planks meet the chine) abso- lutely tight, we laid cotton threading along the chine piece and daubed it with old paint. The keel also was painted before the planks were put in place in order to prevent rotting. Very heavy screws were then set in the edges of the planks and driven into the chine logs, four being placed in each edge; and three were driven down the center into the keel. Before mak- ing the plank fast, however, we made sure that it was square with the keel. The next plank forward was fitted in the same way, and so on fore-and-aft until the bottom was completed. At

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, 1930 ut the ks, gs atten de of then lrawn width f the as a were hness tened ; one atten 3 the were after ed to bevel ; ma- when ttom 4 -in. with th a 1 the done hape and In the bso- ding d it it in Very the into 1 in own nak- ade I. tted -aft At west, north, south, and branches strung across the continent to fabricate and distribute, still could not fully meet the needs of concerns like yours, here and in Canada. ; The Organizing Hand must provide men who know your problems and are able to solve them. How are such men prepared? By having them grow up to today’s difficult tasks through solving a multitude of yesterday’s practical problems, They mastered those tasks under the guidance of older men whose experience had been gained in the same practical way. This progressive experience has been handed down in Grinnell Company through more than half a century. These men know what tomorrsw’s demands willbe, and soare preparing for them in laboratories, machine shops and foundries. Toseethem preparing now for 193 5 is to understand clearly how they have acquired the practical grasp and technical knowledge which you and a nation of other industrial leaders must have now. GRINNELL Branc bes in all Principal Cities *cosor™™ O meet your industrial piping needs the Organizing Hand must provide men. Facilities alone, essential as they are, are not enough. Our great plant facilities, east, POPULAR SCIENCE MONTHLY These men will bring to you greater economy, cheaper maintenance and higher quality in these seven major fields of industrial piping: — 1. Thermolier the copper unit heater. A better and cheaper means of heating many types of industrial and commercial buildings. 2. Thermoflex Radiator Traps with the famous Hydron bellows, insuring perfect operation of your steam radiators. 3. Pipe Fabrication. Pipe bends, welded headers and the Triple XXX line for super power work. 4. Cast Iron Pipe Fittings perfectly threaded, accuratel machined and rigidly inapecsall ° , 5. Pipe Hangers featuring easy adjustability after the pip- ing is up. 6. Humidification Equipment. Complete systems employ- ing the unique automatic control, Amco; furnished through American Moistening Company, a subsidiary. ‘7. Automatic gees Systems with the famous Quartz bulb head. and contractor. COMPANY Executive Offices: Providence, R. I. e world’s largest sprinkler manufacturer 89

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; ‘ 7 ES SER IIE OE Le ONE, SS CSL GS SILLS, Os APRESS + $3 ae edema teere hee Ms came aeanioene. ferme ao SSPE ae chew. 90 the bow, however, the plank was put in place with the grain running fore and aft instead of athwartships. This was done to make it stronger at this point and to eliminate the danger of splitting if the boat is ever hauled out on a rocky beach. At this point we went over the entire boat to see that every screw was set up tight, that none had stripped their threads in the wood and turned loosely, and that the side and bottom planks were securely fastened to the transom. Instead of calking the bottom in the usual way with hammer and calking iron, we found that a small cutting wheel held in a handle was far easier and made con- siderably less noise. Do not calk the seams too tightly because the planks will swell in the water and in doing so they would force out the compound. When the calking of the side and bot- tom seams was completed, each seam was thoroughly covered with a seam composi- tion. This material, especially made for marine use, has the advantage of never hardening the way putty will. It adapts itself to the swelling and shrinking of the planks and does not drop out like putty. The seam composition was permitted to dry on the surface, and the excess mate- rial was scraped off. The composition also was smeared over the fastenings in the bottoms and sides. If, however, you prefer to use a mix- ture of putty and white lead, each seam and screw head mus. be painted first and the putty applied while the paint is wet. This will make it stick in place a little longer. It was now time for us to turn the boat right side up. She was placed on strong boxes to keep her off the floor, and the excess wood was planed from the upper plank down to the point where the sheer should be. In building the upper deck, an arc 0. a circle was marked on a spare piece of wood, allowing half an inch of crown for every foot of beam. In other words, since the boat has a maximum After the canvas has been put in place, it is smoothed carefully with a straight, flat board. SCIENCE MONTHLY POPULAR Marking the bevel on a bottom plank, which is then cut and fastened in place. width of 5 ft., we planned to allow a total crown of 2'4 in. This piece was used as a template for the deck beams up forward. Six of them were made and fitted across the boat. Where the cleat was to be, we put in a doubling piece fitted between two of the frames and flush with their tops. The entire forward deck was covered with scrap material about \%% in. thick, and a deck of the same thickness was also laid along the side. No beams were put under it, as it was supported on the ends of the frames. On the deck we laid a piece of 12-oz. canvas 5 ft. square, after applying avia- etd Putting the forward coamings in place. Note the completed decks and the deck fittings. tion glue to the wood. The canvas was tacked to one side, pulled tight, and smoothed out; the edges then were fas- tened with closely spaced copper tacks about half an inch down on each side of the boat. The after end of the forward deck was made V-shape with the pointed end for- ward. A reénforcing beam was laid under the after edges. A small coaming of 34-in. stock was then fitted across, cut to a V- joint at the center, and carried down to the other side. A coaming of the same material was run down each side against the edge of the narrow side deck. It was butted se- curely against the V-shaped coaming and finished with an “ogee” or reverse curve at the stern. The coaming was fastened by screwing it to the side deck and to the frames. When in place, the coaming projected 2 in. above the side deck and The calking can be quickly and easily forced into the seams by the use of a small metal disk cutting wheel. APRIL, 1930 about an equal amount below it. Be sure that the sheer line is per- fectly fair and smooth before you do any of this work, because a bump or hollow spot in the sheer will spoil the appearance of the entire boat. After putting the seats in place, we removed the crosspieces and put in the round oak molding which runs the entire length of the boat on each side at the sheer line. We also fitted a knee from the keel to the center of the stern piece or transom to hold the engine. Seascoot was painted a dull gray with buff colored seats and deck. The sides were painted white, and the bottom and water line were painted with the best antifouling red copper paint. The water line was painted with the aid of a piece of twine, which was stretched from bow to stern. On her forward deck we put two small chocks to take the anchor line, a cleat, and a flagpole socket. Another flagpole socket was placed aft. All of these are of galvanized iron. A small yacht ensign and small oak flagpoles fore and aft com- pleted the picture. Then came the day of launching. Sea- scoot was carried down the beach and was at last afloat. A small 3'4-horsepower outboard engine was clamped to the stern, and in a few minutes she was cutting the water at a speed of about 9 miles an hour. Seascoot did not leak a drop—and that’s going some for a new boat! We had placed several buckets of water in her before she left the garage, and the moisture had several days to swell up whatever small openings might have been overlooked. Without a passenger, she drew about 1% in. of water at the deepest. point, minus the engine, of course. She has car- ried five people easily and is so stable that with two of us on one side, sitting on the coaming; she tipped up only about half an inch. I should not recommend too much power—certainly not more than 16 horsepower—because Seascoot is not made for racing purposes. Since she is under 16 ft. in length, she requires no Government license; however, she must carry an approved life preserver for every person on board, an approved fire extinguisher, two copies of the Pilot Rules, which can be obtained from any customs house, and a whistle capable of blowing a blast of at least two seconds’ duration (a miouth whistle will pass). Lights for a boat of this type consist of a red and green bow light and a white light at the stern, visible in all directions and higher than the bow lights.

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Aprit, 1930 POPULAR SCIENCE MONTHLY ' | Here are the keys... + | drive it for five days 7 before you decide!” S T : “That’s the kind of demonstra- _ Studebaker dealer's stock, new or used! . tion I want!” More than 150,000 thrifty motorists s er , last year bought Pledge-backed used That’s the demonstration car.” and were satisfied. They bought everyone gets who buys a used _ because they know a good used car is | car backed by the Studebaker a better buy than a cheap car bought Pledge!” new. Most Pledge-backed used cars have been thoroughly reconditioned , ? , P —they look and run like new! Which do you prefer —one-half hour's The Studebaker Pledgealso provides : tide over the boulevards—or five days 4 30-day guarantee on all Certified 7 at the wheel yourself ? cars. It also gives you the honest re- Under thetermsof thefamousStude- _ Presentation of plainly marked prices. baker Pledge, you get five days’ When you buy your used car—a driving trial with the used carofyour _ family car,a business car, ora‘‘second” choice—with this further assurance— cat—see your Studebaker dealer first. if the car you choose does not satisfy, See that you get the protection of the you may return it within five daysand famous Studebaker Pledge — the fair- apply your paymentonanycatin your __ est used car sales policy in the market. STUDEBAKER Builder of Champions 91 Piedge to the Public on Used Car Sales 1 Every used car is conspicuously marked with its lowest price in plain figures, and that price, just as the price of our new cars, is rigidly maintained. 2 All Studebaker automobiles which are sold as CERTIFIED CARS have been properly reconditioned, and carry a 30-day guarantee for replacement of defective parts and free service on ad- justments. 3 Every purchaser of a used car may drive it for five days, and then, if not satisfied for any reason, turn it back and apply the money paid as a credit on the purchase of any other car in stock—new or used. (It is assumed that the car has not been damaged in the meantime.) | IE A LOTT SR ESS. —_—_—_— © 1928 The Studebaker Corporation of America you may save $200 Spend 2c now for your copy of this interesting and in- structive booklet, “How to Judge a Used Car” —it may Save you as much as $200 on the used car you buy. Mail the coupon — now / THE STUDEBAKER CORP. OF AMERICA Div. 164; South Bend, Indiana Please send me copy of “How to Judge a Used Car.” ie INVEST 2c | . a oe Sor Cons seeevestts

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More Wa Wire to Work By HENRY SIMON O MANY are the uses of wire that every mechanic, amateur or profes- sional, needs to know how to handle it expertly. And, strange to say, there are more “kinks” in using wire than anyone is likely to think—save, perhaps, the apprentice who carelessly snips apart a tightly wound coil of music wire and discovers all at once what a lot he has to learn A number of suggestions for manipulat- ing wire and applying it to work of various types, together with designs for a cutting machine and a winding tool for use in the lathe, are given in this article. These sug- gestions supplement the twenty-five hints on wire previously published (P. S. M., Mar. ’30, p. 90). A small, tightly wound spring of the door spring type has a limited use as a belt for transmitting motion as in Fig. 1, although it is unsuitable for a regular drive. Sometimes it can be used to advan- tage where a light though definite tension must be maintained as at B, or where the distance between two pulleys is periodi- cally varied, as at C. Other points of use- fulness are its indestructibility, its capac- ity to stand heat up to 500° F., at which temperature ordinary belting would im- mediately burn up, and its ability to work efficiently in oil and in hot and even boil- ys to Put Fig. 1. Coil wiredrives. Fig.2. Wire asan aid todraftsmen. Fig. 3. A strong cylinder, Fig. 4. Hints on handling wire. POPULAR SCIENCE MONTHLY APRIL, 1930 ing liquids, as at D. A sheave type pulley having a section like that shown at E is best for such a belt. The mechanical draftsman rarely thinks of wire as a possible help to him, but even he can put it to work on his board. Soft or half-hard wire, bent to any flat shape, may be used for an odd-form template as shown at A in Fig. 2. A similar end is served by the combination of hollow wire and piano wire, menticned last month for other purposes, and arranged as at B, to make a flexible rule for the drawing of curves. Though such a rule does not automatically lie flat, it has the advantage of being quite inexpensive and practically unbreakable. And very fine, soft wire used in connection with pins of fairly large diameter placed at the foci, is superior to string for drawing ellipses of large size as shown at C, because it has practically no “give.” NAVAL gun construction has a Jesson 4 to teach the experimenter by remind- ing him how wire can be employed for producing the strongest possible tube or cylinder of a given weight and size. This is done by sandwiching one or more wire windings between two steel shells, as at 4, Fig. 3. One way of producing such a com- bination shell is by making the wire winding in the form of a close-wound, tight-fitting coil spring, “‘screwing’’ this spring on the part by turning it oppo- site to the direction: of the winding, as at B, and then shrinking the outer shell on, as at C. In working with high- pressure gas, hydraulic, or other expansive pressures, such a construction may be useful because it combines safety and light weight and requires little space. There are a few simple tricks in handling wire that it pays to use—none better than the simple “safety first” kink shown in Fig. 4 at A. This is the practice of bending the end of any spring wire back upon itself in a loop after every handling or when cutting off long pieces. Heavy piano wire, done up in the overwound small coils in which it is com- monly sold, is a dangerous thing, and this simple precau- tion will save many injuries. Another aid in taming this sometimes uncontrollable prod- uct is the wooden coil cage shown at B. The whole coil, tied as it comes, is placed on a wooden hub, and a bar is then RAN Complete details of this coil-spring winding de- vice for use in a lathe are given in Fig. 6 on page 94. put in place to retain the wire. It may be observed that neither this nor any other expedient will ever make it satisfactory to handle spring wire put up in the tight rolls in which small quantities are sold. At C is shown a wall hook suitable for hanging soft and half-hard wire. It is more satisfactory than the ordinary hook because of its added length, as indicated at D. The machine shop mechanic has little need for the splicing of wire, but frequent occasion for bending, winding, and cut- ting it. Cutting wire to length with pliers is tiresome when a large number of pieces must be so obtained. A simple cutting device that cuts and gages any size wire and can be used in either a vise or under a press is shown in Fig. 5 at A, B, and C. The interchangeable bushings can be readily made to fit any size wire, and are easily reground and reset, as is also the cutter slide which is shown in detail at D in Fig. 5. Wire forming is a complicated art and science in itself, but a suggestion of a simple rigging for bending limited num- bers of duplicate pieces is given at E, Fig. 5. The pins should be no longer than necessary and well rounded on top to pre- vent any possible injury to the fingers. As indicated at F, the same plate can be used for numerous parts of different shapes. EVERAL effective hand tools exist for winding wire, and usually these suffice for ordinary shop purposes. Where higher accuracy is required or where many coils must be wound, a more mechanical way of winding sometimes becomes advisable. A lathe tool for this purpose is shown at the top of the page and in Fig. 6 at A. It consists of a base block a, which is mounted on the compound rest, and a wire-feeding float b capable of a limited movement parallel to the lathe spindle axis. Nuts c acting against a spring d allow the float body to be adjusted to various heights to suit the spring diam- eter being wound. With this device, springs of tight tension can be wound practically without regard to the feed; or coils may be spaced the exact feed dis- tance apart by locking the float against blocks placed underneath it. With spring wire, it is useful to remember that the diameter of the coil spring can be changed with the same arbor by varying the sliding

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Rey eat ae ApriL, 1930 POPULAR SCIENCE MONTHLY & 2 Le - : — 20 . . . P : ' ¥ # CATALOG Put the NEW Starrett Catalog in your kit. Old familiar tools, improved tools, new tools— you'll find over 2500 of them in the latest Starrett Catalog, ‘No. 25 W, just out. Tear out the coupon ..... Mail it today. RESIN IEE TTT OS AE RS A RET ON I SOT TU ATE MEP NS OS AT PE A : hose Serer ee ee = : eee - Ee ? SSS SSANRRERe remence SI RAxA STARRETT] IOOLS @ This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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94 friction and thus altering the tension of the wire. Something that rarely becomes neces- sary in the average shop is the reduction of wire by drawing. Nevertheless, it is useful to know how it can be done, and Fig. 7 at A shows how to doit. The die should be made of high-carbon tool steel, and the taper hole through it should be left from .0005 to .001 in. small for lap- ping. Fine wire can be readily reduced by a few ten thousandths by pulling it through the die by hand as at B, the end having first been tapered down to pass through the die. Redrawing is particularly useful in bringing hollow wire to the exact POPULAR SCIENCE MONTHLY ‘size, because this wire ordi- narily runs to limits of plus or minus .002 in. By drawing, it can be held within limits APRIL, 1930 FLOAT, : ‘. ' i of plus or minus .00025 in. and even less. The incoming end of the wire should be kept well greased. Do not attempt to i SB reduce wire by more than about 5 or 10 percent at one drawing, and less will be neces- sary if any great amount of accuracy is essential. Almost all of the uses to which wire can be put require that the wire be bent; and un- less the mechanic FIG.5 has some knowledge of the bending limits of the wire that he is using, he will encounter diffi- culties. A list of the approxi- mate bending radii for various Fig. 5. Device for cutting and gaging wire, and an adjust- able form for bending a limited number of duplicate pieces. tempers was given in the pre- ceding article on this same subject (P.S.M., Mar. 730, p. 90). This article also con- tained hints on casehardening wire and a table of the dura- tion required in the process of casehardening, strengths of wire, forms of sockets for use in connecting wire to machine parts, the uses of wire for ma- chine drives, the use of wire as a reénforcing agent, and the use of wire for the transmission of a push or a pull. While these two articles do not cover the entire subject of wire handling, they will give Dividing Work in the Lathe Yyyore being machined in the lathe can be laid out for drilling equally spaced holes by the method illustrated. A surface gage and plate and a prepared three- or four-jawed chuck are the means employed. The chuck must be machined true on its outer cylindrical surface and then di- vided into 360 equal parts. This can best be done by placing the chuck on an arbor, machining it in the lathe, and then placing it on the dividing head of the milling machine. The work itself is placed in the chuck and machined as necessary up to the stage when the hole centers are to be laid out. Then the circle for the centers is cut lightly on the sur- face by means of a pointed tool. To ascertain the correct spacing, place the surface gage on a steel plate and set the scriber to the center line of the lathe. Move it to the side of the chuck as shown in the oper- ation marked “dialing,” set the chuck at zero, and then bring the gage around to the front of the work and scribe a line, as shown under the heading “scribing.” Where this mark intersects the circular center line first drawn is the location - ln», = } for the first hole. Repeat this spacing process, moving the chuck through the number of degrees desired. In this way it is possible to mark the centers for holes quickly and accurately while the work is still in the lathe and thus eliminate the necessity of placing the stock in the dividing head of the milling machine before it is taken to the drill press to be drilled.—GrorcE A. McCULLEY. A a The arrangement, of the surface gage and plate, and the two steps in the process of spacing the holes. Fig. 6. Front, top, and side views of the lathe coil- spring winding device. Fig. 7. How todraw wire. the mechanic and the home worker a sound working knowledge of wire as an aid in the solution of shop problems. Articles dealing with thread cutting and the uses of sheet metal, both of which are by Mr. Simon, are scheduled for early publication. An intensely practical discussion of boring problems in the jobbing shop has been pre- pared by Hector Chamberland, and the first installment is to appear in the May issue. Old Bill Says— 4 GRIND aluminum or its alloys cylindrically, use kerosene and water if no grind- ing compound is available. Educate yourself to safety habits; it will be profitable to you fand to all those who work with you. To give a tool made of stel- lite a high finish, dry-grind the last .0005 in. A little practice each day in left-hand filing will make the — much safer for lathe work. Observe the back and forth movement of a power hack saw and apply the same principle to your hand hack saw. See that the pilot of your center drill does not get too short and you will rid your- self of the source of many errors. A good machinist never loosens a tight screw with a prick punch.

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Aprit, 1930 POPULAR SCIENCE M ONTHLY 95 Brown & Sharpe Depth Gauges answer accurately the question “How deep?” ‘There is a Brown & Sharpe Depth Gauge to meet every requirement. The variety of designs, all maintaining the rigid Brown & Sharpe standard of accuracy, makes them exceptionally popular with skilled mechanics. Micrometer Depth Gauge No. 607 Range 0 to 3” by thousandths of an inch. An accurate tool which is espec- ially handy to use. ee Rod Depth Gauge No. 614 Range 0 to 3”. Depth of hole is read from the graduations on the body of the gauge. The small diameter of the rod permits its use in small holes. Vernier Depth Gauge No. 600 Graduated to read in 64ths on one edge and by means of a Vernier, in thousandths of an inch on the other. Furnished with 6’ or 12” blades. Drill Point Gauge and Depth Gauge No. 617 Range 0 to 5". No. 617 can be used for checking angles of drill points when grinding them and determines whether the point is central, or it may be used as a depth gauge. Furnished with 6” rule and 6” rod. The full line of Depth Gauges is described in our Small Tool Catalog No. 31. Send fora copy. Dept. P.S., Brown & Sharpe Mfg. Co., Providence, R.I., U.S. A. Brown & Sharpe Tools * WORLD’S STANDARD OF ACCURACY” © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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ee = Ses ene ee Se : SNe OS AEA oe oa SI ant eee ote aie arr reer +e ARE, at ae. Ee 5 inns 2 96 The dtnging Shave for Facial Harmony A smile on your face, a sparkle in your eyes, and asong on your lips when the Ever-Ready glides away with your beard! For it is gentle, swift, better. It gives more shaves—yes, many more shaves. Buy Ever-Ready Blades— join the chorus of Singing Shavers. Product of American Safety Razor Corp. Ever-Ready BLADES POPULAR SCIENCE MONTHLY APRIL, 1930 By W. CLypr LAMMEY it supplies ample room for books and current magazines is one of the outstanding features of the end table illustrated. * For its construction the following is needed: 1 piece of % by 14 by 24 in. 5-ply walnut veneer, 1 piece of 3% by 24 by 48 in. 3-ply walnut veneer, 2 pieces 4 by 10 by 20 in. red gum, 1 piece %%& by 4 by 20 in. red gum, and 2 pieces %%@ by 12 by 28 in. red gum. All this material may be ordered from the mill cut to size and dressed, if desired. Cut the two %4-in. gumwood end pieces to the exact length indicated and joint (plane) the edges true. Lay out the separate designs of the scrollwork on pieces of card- board and, using them as tem- plates, transfer the designs to the wood. Saw to the outline with either band saw or scroll saw. Sand the edges of the scrollwork thor- oughly, making sure that all traces of the saw marks are removed. Lay out the shape of the top on the piece of walnut plywood and carefully saw to shape with scroll or band saw. Joint the edges true with a jointer plane and sand the rounded corners. The bookracks are made by cutting two pieces of 14-in. stock to size and beveling the top edge of each at an angle of 45 degrees where indicated. Rip the narrow strips left from the original wide pieces each to 2 in. wide and use as the rails. Fit the ends to the top by placing the inner edge of the upright 23% in. in from the outer edge of the top, and fasten with glue and screws. Cut two triangular bookrack blocks U SEFULNESS in thesense that 12 Oa “MITERED EDGE---" 19 56° MAGAZINE POCKET LAY QUT 2-IN. and other parts. FOR PLOTTING CURVES Dimensions of the end pieces, magazine pockets, top, Note the construction of the book- shelves, magazine compartments, and curved stretcher. Magazine-Rack End Table The bookshelves will hold more than thirty volumes, while the magazine racks provide space for periodicals. from %%-in. stock and fasten one in place in the center of each upright end piece. Set the bookshelves in place over the blocks; and when the beveled edges at the top fit snugly, nail the shelves in place with several small finishing nails, sinking the heads with the nail set. Cut all pieces for the racks from 34-in. plywood to the dimensions shown. Run all rabbets to a depth of 1% in. Lay out the scrollwork with a paper template as before and cut the upper edges to shape. Rabbets in the pocket ends fit over the edges of the end supports of the table. The two centerpieces for the pockets are trimmed to fit after the pockets are assembled. They are not glued in their grooves but are left loose for cleaning. Saw out the piece for the ornamental stretcher from the 4-in. gum- wood, sand the edges of the scrollwork smooth, and _ nail and glue in place. Clean up the entire surface with fine sandpaper and stain the gumwood parts with a walnut oil stain, wiping the stain lightly so that it dries evenly and matches the walnut plywood. Next, fill all of the walnut surfaces with walnut paste filler, taking special pains with the nail holes. Using No. 8-0 wet-or-dry sandpaper and either linseed or rubbing oil, rub all parts to a smooth sur- face. Clean with a cloth and turpentine and then give the entire table two coats of high- grade varnish. When dry, rub to a dull satin finish with powdered rottenstone and oil, clean off, and polish with a soft, dry, lintless cloth.

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Lice il ce in 1€ es it it te , r- d le s April, 1930

POPULAR SCIENCE MONTHLY YOU CAN AI 97 EAR THE DIFFERENCE AND GEE THE REASON IN EVEREADY RAYTHEON 4-PILLAR TUBES HERE is an entirely new type of tube ... Eveready Raytheon! It combines the highest degree of sensitivity with lasting, rugged strength. The patented Eveready Raytheon 4-Pillar construction— a revolutionary improvement—safeguards fragile elements against the dangers of shipment and handling. Eveready Raytheon elements are assembled on jigs, to put them in most sensitive relation to each other. The 4-Pillar construction anchors these elements where they belong—assuring you of a new standard of reception. You can see this exclusive construction inside an Eveready Raytheon. Look at the diagram on this page. See the solid, four- cornered glass stem. Notice, imbedded in it, the four sturdy pillars 4-PILLAR TUBES supporting the elements. That shows why Eveready Ray- Showing the exclusive, patented EVEREADY RAYTHEON 4-Pillar construction, with its solid, theons are stronger than or- four-cornered glass stem, its four rigid pillars, < and anchorage to a stiff mica plate at the top. dinary tubes—and why they give you the best reception you can possibly get from your present receiver. No other tube can be made like this, because the 4-Pillar construction is patented.

Eveready Raytheons come €

4-PILLAR SCREEN GRID EVEREADY RAYTHEON SCPEEN GRID TUBE, ER 224. The weight of the four large elements in this type of tube makes the exclusive Eveready Raytheon 4-Pillar construction vitally important,

© This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. in alltypes. They fit the sockets in every standard A. C. and battery- operated receiver in use today. They are built by the makers of the famous Eveready Layerbilt “B” Batteries—another radical improve- ment in radio. Get a set of new Eveready Raytheons from your dealer, and enjoy their reception today. EVEREADY RAYTHEON

NATIONAL CARBON CO., Inc. General Offices: New York, N. Y. Branches: Chicago Kansas City New York San Francisco Unit of UCC and Carbon Union Carbice Corporation

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They plan world peace Smoking Pipes and sitting on a log WO statesmen sit on a log and smoke their pipes and plan the peace of the world. It is a moment of history, and pipes belong with it —for pipes are symbols of peace. Men of thought and men of action relish the savor of the robust smoke that nothing but a pipe can draw from good tobacco like Edgeworth. Slow- burning, cool and benevolent, with a flavor all its own, Edgeworth is the choice of many a smoker. If you have been missing either pipe or Edgeworth, why not try them now together? Real smoking pleas- ure will be yours from the first puff | on, for Edgeworth never changes and you can buy it anywhere. May we not send you, with our compliments, some Edgeworth to try? Let the coupon be “yes.” Edgeworth is a combination of good tobaccos — selected carefully and blended especially for pipe-smok- ing. Its quality and flavor never change. Buy Edgeworth anywhere in two forms— "Ready Rubbed”’and “Plug Slice." All sizes—15¢ pocket package to pound humidor tin, EDGEWORTH SMOKING TOBACCO LARUS & BRO. CO., 100 S. 22d St. Richmond, Va. I'll try your Edgeworth. And I’ll try it in a good pipe.

My name

My street address

And the town and state

Now let the Edgeworth come ! Cnceaseens ane aa ae ae ane am ae <a 5

POPULAR SCIENCE MONTHLY APRIL, 1930

| Howto Makean Embossed “| Teather Trinket Box By F. CLARKE HUGHES EW tools are needed in the construc- Pin of the attractively embossed leather can be quickly cut to shape with a sharp knife, and the embossing proc- ess is accomplished through the use of simple wire forms which are pressed into the surface of the leather. While the drawings show the dimen- sions for a box 24 in. square, they may be varied if it is kept in mind that the top | must be large enough to fit over the main | body of the box. A good rule to follow is | to make the outside of the lid about three times the thickness of the leather larger | than the outside of the box itself. It is well in constructing a box of this sort to make a cardboard model by cut- ting pieces as required and folding them to shape. The patterns thus obtained can be used in cutting the leather to the exact shapes. After the two parts of the box have been cut out, the holes for the lacing can be punched and the edges mitered to | allow folding. The holes in the lid should be about 1% in. in diameter, while those in the body of the box need be only large enough to receive a medium size sewing needle. The holes can be punched with either a regular leather punch or with a nail filed flat and used on the end grain

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WIRE FORM FOR EMBOSSING DESIGNS

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NAIL ON THE ENDGRAIN < | OF A BLOCK

sole leather trinket box shown. The - sonangegeannnanaentononses Cr FOR FOLDING

HOLES MAY BE PUNCHED WITH SMALL The dimensions are principally to indicate the proportions; the box can be made any size desired. Note the method of stitching.

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sa The leather box forms a neat container for odd buttons and small sewing accessories.

of a block of wood asina sketch below. The embossing is accomplished by the use of wire bent to the desired design as illustrated. These forms can be made of either square or round stock. Two forms can be made and the embossing process repeated until the four faces and top are embossed; or five frames, four for the sides and one for the top, can be made and the entire process completed with one pressing. Wet the leather, place the wire forms, and insert the leather, forms, felt pads, and blocks into a vise or old letterpress and apply the pressure (P.S.M., Feb. ’30, p. 96). 4 After the lid has been embossed, wet the leather along the lines of the cor- ners and bend the parts to shape. The lacing, which can be of any leather—kangaroo or wallaby skin, however, being preferred—should be cut about % in. wide and 5 a 3 a ee laced in the holes in the LACED_|s [| manner illustrated. _ = ul If desired, the inside of /* THE WIRE FORMSARE PRESSED the box can be lined with | = INTO THE WET LEATHER kid, lining leather, or or- r DESIGN dinary felt by cutting the ed leecesee} SPACE material to the shape chosen “Eos sl ae for the main part of the } ° 5 | i. : ‘ ° ° ba 2% rE ito box and carefully gluing it Ce aes ARE CUT eget meg After the box has been assembled and laced, the entire outer surface should

PUNCH HOLES -—s _ bepolished thoroughly with FIRST BEFORE Lt | ordinary wax or shoe dres- SEWING if! 5 | sing. ts SEWED WITH 4 pint edd sess SLR THREAD This is the sixth of a series of articles by Mr. Hughes dealing with applications of this new, easy, and efficient method of embossing leather. A handsome leather book cover is his next project.

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1930 April, 1930 POPULAR SCIENCE MONTHLY 99 Joell wv. ne aS of A! 1S sS “ & Ni ... for him who revels in the rush of the wind, the warmth of d \\ the sun...an Indian... the sportsman’s steed... a lithe, le gO live companion of the highway. It’s the outdoors man’s way , to go places . . . swiftly, smoothly, safely. No waiting in traffic , delays . . . no crawling up hills behind “Sunday drivers.”’ s Get astride an Indian . . . feel the thrill of the surging power : between your knees... feel your blood tingle as you slip n through traffic like a cat—out to the open highway, with the . breeze in your hair! 0 An Indian is Safe e And remember—lIndian has a reserve of power to pull you ‘ quickly out of danger, yet it is light enough to stop in half : the space a car needs. Indian’s a tough machine, too—a stock model holds the world’s record of 497 hours continuous running, beating the famous “St. Louis Robin”’ plane endurance record. That's stamina—one of the things twenty-seven years success- a ful motorcycle making puts into’every Indian. That’s why New York City’s great motorcycle squad, and those of many other cities, are exclusively Indian equipped. Thousands of merchants, INDIAN goes nautical, too! too, use Indians for quick, economical delivery service. Now you can enjoy on the waterways famous, dependable /ndian power in ) ia Visit your local Indian dealer. See the Improved Indians— CHIEF 74, SCOUT, and FOUR, and the new Indian Silver ¥ 4, Arrow Outboard Motor. Or write Indian Motocycle Company, OUTBOARD MOTOR Dept. C4, Springfield, Massachusetts. A Class B outboard, em- bodying all the experience Indian has gained in 27 years of —— small power plants. lower, speed; stamina—all you look for in an outboard, lus an ease of starting itherto unknown. er we ae FF He ee

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a ™ ‘ St‘ jS[te St ieaniicas So oT APR. 2 maPhater rte “ ere > Fs ‘ a] 4 ; a : ‘ y ee eee PESOS: BOLE ILL FD ~ me NER eee ~ : Sat ER Eee ae ERAN ee eo Tee See ean Re, — Lapewo ree oa aaa 1B: « saa: a ne a Soe Print — 100 POPULAR SCIENCE MONTHLY APRIL, 1930 DURA TRAOE MARK DRIVER REG. U.S. PAT. OFF The World’s Greatest Screw driver at Anywhere Near the Price are the sensation of the market—ask for a Dura Driver at your =>. hardware or auto accessory store. | “The world’s largest makers ot ‘Tue Vicnex Toot Co., Clevalend, © | Copyright 1930 The Vichek Tool Co. Builds Home in Spare Time The front of the house showing the brick terrace and semicircular concrete porch. UILDING bit by bit during his spare time, R. J. Stephens, of Kansas City, Mo., constructed the remarkable five-room bungalow _illus- trated. It is thoroughly modern, even to a built-in garage, and its materials are of the best quality throughout, yet the cost for the house and a 50 by 142 ft. lot, exclusive of Mr. Stephens’ labor, was only $2,500, every item having been recorded. But can other readers approach this feat? Mr. Stephens believes they can. “Tt seems to me,” is his modest com- ment, “that what I have accomplished should be an inspiration to anyone with a little capital and a little credit and a whole lot of stick-to-it-ive-ness.” Nevertheless, the many curious visitors who inspect the house and all his friends wonder how it is that he could have acted as carpenter, designer, bricklayer, concrete worker, painter, decorator, pa- per hanger, electrician, plumber, drafts- man, and tile setter. About the only thing he did not try was the plastering. The surprising fact is that he has never earned wages at any of these trades; he is the secretary and treasurer of a con- fectioners’ equipment company. A spacious living room and the built-in garage are not the only features of this dwelling. In designing the house, Mr. Stephens’ first thought was for a con- venient, sensible plan. He was not satis- fied with the commonplace plans he found in books and catalogues, so, with the help of Mrs. Stephens, he laid out a floor plan that would give each room ample sunlight and ventilation. Both the kitchen and the bath- room are placed to give the utmost privacy. The kitchen is espe- cially easy to air, because in addi- tion to a window and a door leading to a large back porch, it is pro- vided with a ceil- ing ventilator. The free use of arches insures bet- ter ventilation of The designer-builder and his wife, who helped him in many of the problems relating to the planning. Reader constructs large five-room bungalow for $2,500 including price of the lot, and incor- porates a number of conveniences together with a built-in garage. The built-in garage is entered from the rear of the house by means of a ramp. other rooms and gives an appearance of spaciousness which many small houses lack. The built-in garage has a door leading into the basement. This allows Mr. Stephens to go right from his warm house into an equally warm car that will start at the first touch of the starter but- ton even on the coldest mornings. The garage is 8 ft. wide and nearly 18 ft. long. It has a 7-ft. ceiling, the doors being 4 by 7 ft., a standard size. The in- terior is lined with heavy fireproof plaster wall board, which meets with the require- ments of the local building code. In localities where all masonry construction is required for built-in garages, it would be necessary to use brick, concrete blocks; asbestos blocks, or whatever the code specifies. The ramp leading to the garage rises 1 ft. for every 41% ft. in horizontal length, and is 18 ft. long. As it approaches the doors, the driveway is nearly level; in fact, it rises slightly from the outside drain to the doors. This part of the drive is slightly lower than the ga- rage floor so that the doors can fit tightly against the vertical face of the concrete and still allows ample clear- ance for them to swing clear over the level portion of the drive. Ample drainage for the ramp and garage was ob- tained by having one drain inside the garage and one on the level part © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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1930 Id ill ze id 1g le 1e rt

ApriL, 1930 POPULAR SCIENCE MONTHLY 101

LOSE your eyes. Can you picture the time when you have completed your solo-flight and your friends rush out to con- gratulate you? Or, when you have qualified as a Master Mechanic and are directing the work of others? Or, when you have made a place for yourself in this big, new, rapidly growing industry? Every young man with a spark of ambition can see his goal in his dreams. But the young man who is wise takes action at once to make his dreams come true. Where to Start There is no better way to start than to send for this book, “ Aviation—What It Means To You."’ This book describes, without ex- aggeration, where aviation is going and the opportunities it offers. it answers your questions and gives you information you should have. It explains in detail the vari- ous acronautical and business courses of- fered by this national system of schools. It gives you an accurate picture of each of the schools in the system—tells about living conditions, equipment and costs. It is amply illustrated from cover to cover. If you are at all interested in aviation, you should have a copy. What Universal Aviation Schools Are Universal Aviation Schools are located in various sections of the country. They are owned and directed by the Universal Avia- tion Corporation, a division of The Aviation Corporation which, with its affiliated lines, = Air cooled motors and modern production ships are studied from both theoretical and practical points of view. - DREAMING won't start you in Aviation, young man. It takes Action~

It is impossible to ob- _tain better or ve / modern ipment than ‘is fountin Uniwersil Aviation Schools. / Planes are all govern “ ment licensed and in- structorsarealllicensed ] transport pilots. operates over 19,000 miles of air- ways a day, carrying air mail, ex- ‘3 press, and passengers. Each in- dividual school has been provided with the most modern equipment that money can buy and the most | efficient instructors obtainable. {4 All instruction is strictly in ac <% cordance with regulations of Bureau of Aeronautics, De- partment of Commerce. The safety and excellence of Uni- versal training is indicated by the award to Universal flight students of the first insurance protection ever issued by the insurance industry. This Book Is Free, Mail Coupon Wake up to the possibilities of aviation. Get into the industry before it is crowded. Think! Six weeks from:now you may be a pilot. But you must start at once. Begin today by mailing the coupon for this in- teresting free book. Universal Aviation Schools A National System of Government Approved Aviation Schools. Universal Flying School ._. St. Louis, Mo. Universal Flying School . Memphis, Tenn. Universal Flying School. Minneapolis, Minn. Universal Flying School . Cleveland, Ohio Universal Flying School . . St. Paul, Minn. Universal Flying School. Kansas City, Kan. A Division of The Aviation Corporation UNIVERSAL AVIATION | | 7 UNIVERSAL AVIATION SCHOOLS Suite 1046-55 Boatmen’s Bank Bidg., = 7 St. Louis, Mo. BUR HIGHWAYS” e} Please send me at once your free book, ** Aviation—What It Means To You.”’ I am interested in:

C)Flying Course (_jAviation Mechanic's Course [| |Business Course [JExtension Home Study Course DG 5. faba vesE ss nnnees becdneweee Age... Ss 65. Pie Ra ok ook os odetwe Bette dats MRA pera Cit State N318RI Acronsutioal PT ee eee } Commerce.

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Whether yo ing jobs a ye — you want#ic precision 2 on your p why Greerfite joy to the handle p tools. Jom few pipe thread- ra few thousand s that work with ith as little effort s possible. That’s Pipe Tools are a who has tried to ing with ordinary ly new process in dies, Greenfield has ¥% to % the amount and consequently the threading. Greenfield dies aggt@mrvelously accurate, and cut iron or brass pipe with amazaaimase. By an making reduce of “d effort These famous tools are enameled bright red. Remember the color! It assures you easy cutting, accu- rate, long-wearing pipe tools. Our special Pipe Tool Catalog sent free on request. Cased tort D Cv CORPORATION GREENFIELO, MASSACHUSETTS POPULAR SCIENCE MONTHLY APRIL, 1930 Zz rr] 5 = x LIVING ROOM TERRACE CONCRETE TERRACE CKWORK 33-0 WIDE FOUNDATION 24-8" DEEP The large living room, with archways leading to hall and “‘dinette,” is a feature of the plan. of the ramp (see illustration at right). Drainage is most important in con- structing a basement garage of this type. There is the possibility, even with the construction shown, of finding,the doors ice-locked, but not if one is careful. The outside drain should always be kept open; do not depend wholly on the inside drain. Before ice will cake in front of the doors, there must be snow or water, therefore do not allow any snow or water to accumu- late. As an extra precaution, it is well to have a small trench about 3 in. deep right in the concrete floor of the garage leading from the drive under the doors to the inside drain. Then, if the outer drain is frozen up, the surface water formed when the ice thaws on top will pass through this trench to the inner drain. This is important, for if the outer drain is once frozen up, it will be the last to thaw out; and if there came a succession of thawings and freezings, it would not take long to have thick ice in front of the garage doors. The terrace in the front of the house rests on a heavy subfoundation, which in turn is anchored to the main house foun- dation by means of steel reénforcing rods. The large concrete semicircular porch rests on I-beams which also are securely anchored. The terrace is faced with tapestry brick set vertically and is so reénforced and bound to the concrete that it has not been affected by frosts. Many economical kinks were used in the construction of the house. For in- stance, the heavy brackets which serve to support the gable over the front door were made from scraps left over in cutting the end gables. RETAINING WALL OMEN ys Fe iw. Ae i INSIDE: x * DRAIN =. : oh Be OF a> gos? wr, g: Miya" - UM wit ‘ft bay “ S 7 xy SHALLOW TRENCH Cutaway view of entrance to the basement ga- rage, showing method of draining off the water. Varnish Sticks Cloth to Desk Top F A cheap, thick, quick-drying resinous varnish is used as an adhesive, a desk or table top can be re-covered easily with cloth or, for that matter, genuine or imitation leather. What is known as patching varnish will answer quite as well, but a cheaper and thicker varnish is still better. Suitable cloth or leather may be had at many different shops. Felted cloths in colors are made for this purpose. Billiard cloth is excellent, pro- vided the green color is satisfactory. Cut the cloth with plenty of overlap on all sides. Then roll it the nar- "Et row way, face in, and lay it aside tempo- rarily. Spread the varnish thickly but smoothly on the desk or table top and see that the edges and corners are well covered. The varnish, when ready to receive the cloth, should be so tacky that it will stick to your fingers when you touch it. Let it stand until very tacky and watch it so as to catch it at just the right moment. As a prelim- inary test, it is well to spread a little of it LINE CUTTING 3; When the varnish on the desk or table top is tacky, the cloth is rolled in place and trimmed. on a board and time it; then you will know just how much time to allow. Unroll the cloth over the varnish and smooth it with a roller, if you have one, without pulling or stretching it in the least. See that the edges are firmly pressed down with a block. Lay a thin-edged rule on each waste edge, exactly on the line, and trim it with the point of a very thin, keen knife blade. Hold _ the knife at a fairly low angle in order to make a slicing cut. Press down the edges with a block and watch it for a while to make sure the edges will stick. If your varnish was sufficiently tacky and your trimming good, you will have a fine looking top; and the cover will never annoy you by coming loose and rolling up into dog ears at the corners. Be sure, however, to allow the varnish to reach its maximum degree of tackiness before ap- plying the cloth or leather to the top of the table—HENry GEORGE. © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. N the Ho to pa) a © TD he ee eee eet OT) OM bed FD es eet Ph TD

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130 8 CD me 8 ww § Wye VS FSO ON = Apri, 1930 | Making a Balancing Gander of Wood HE steadfast man is a well-balanced man—and the same is true of this gander! Its steadfastness, however, de- pends upon the weight of a lead slug. For making the gander, one piece of pine or whitewood 3 by 2'% by 6 in. and one piece 34 by 2% by 3 in. are required. Draw 14-in. squares on each as shown and reproduce the curves. Lay out carefully and cut accurately the notches that form the joint, which must fit well but not so closely that either piece will be split. Saw the curves, plane the taper from the shoulders BB to the top of the head as indicated, and smooth the edges with a file and sandpaper. The broad surfaces should be sanded smooth and the joint lightly glued together or held with a Lrad as indicated at C. Drill a %-in. hole 34 in. deep as at A, drive a brad in it'as at D, and pour melt- ed lead into the hole; the brad D will hold the lead in place. Paint the gander in brilliant colors.— CHARLES A. KING. ae ~ 4 " LEAD SLUG , Ye SQUARES Wii" X 3/4!” The cuts which form the joints should be made accurately to insure a perfectly tight fit. Where to Look for Other Mechanical Articles ANY short articles of interest to mechani- 4 cally minded men are scattered through the magazine in the sections preceding the Home Workshop Department. If you happen to have missed any of the following, it will pay you to turn back to the pages noted and read them. Square, Gage, Plumb, and Level.... 30 New Core for Castings............. 30 Harden Steel by Magnetic Process... 30 New Composition, Hard and Flexible 46 Steel Mill Operations.............. 63 Model Steam Locomotive.......... 64 Collecting Rare Woods His Hobby.. 64 Ship Model Carries Crew........... 67 Sweepings Disappear in Dust Chute 68 Diminutive Household Jack........ 69 Outdoor Incinerator Dumps Itself... 69 How Many Tubes Do You Need?... 71 Helpful Hints for the Radio Fan.... 72 Pia 0 Peer re 72 Shifting Antenna to Avoid Static.... 73 POPULAR SCIENCE MONTHLY 103 / the finest car © 7 the finest radio / the finest bit-brace —If you want one, you want the other... Because you are modern; and know the pride, pleasure, and econ- omy, of owning the finest thing of its kind! The “Yankee” Ratchet Brace is one of the fine things that any man can afford. If you work with tools— either as mechanic or amateur, you hardly can afford not to buy it. Buying the *“Yankee”’ Brace, you will never have occasion to buy an- other bit brace. “Yankee” Chuck will not loosen The famous “Yankee’’ Ratchet is smooth, silent, powerful. Bronze encased—against dust and moisture. Ratchet adjustment is instant, positive, and visible. A glance tells how ratchet is set; a finger-touch changes it. No need to hold chuck I am “modern,” I ho **Yankee” Ratchet too drivers, Ratchet Pusb Ratchet Chain and Bench to keep bit from turning back. “Yankee” Chuck centers bits accurately; locks and re- leases instant- ly. Holds any shape—round, ~ Visible square, any Ratchet Shifter taper; and will pot loosen in work. “Yankee” Hard-rubber Handles (both top and side) do not warp, crack, shrink or bind. Top handle steel clad; ball bearing. Ask dealer to let you try the “Yankee” Brace. See for yourself the economy of owning the finest tool of its kind. No. 2100. — “Yankee” Brace. Four sizes: 8, 10, 12, 14 inches. Two- jaw chuck; 14” round; 5%” square (across corners). Price, 10-inch sweep, $8.20. “Yankee” “YANKEE” Bit Extension No. 2150 No jaws. It holds bit in socket! No loosening and pulling out of bit in work. Can’t jam. Fits any . Follows through. Stands abuse. Four lengths: 15, 18, 21, 24 inches. Prices, $2.25 to $2.40. “YANKEE?” on the tool you buy means utmost in quality, efficiency and durability NORTH BROS MFG. CO., Lehigh Avenue, Philadelphia, U. S. A. . You may send book showing action pictures of famous : such . seers ral Ratchet Screw- Screw-dri . as v 8 et Ratchet Push Braces, Ratchet ireast and Hand Drills, lis, Ratchet Tap Wrenches, E CORPO EEE HEHEHE HE EEE HEE HEHE EHH EEEEEEE HH EOS © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. SAAT CRT ee wt a we 2 ee

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104 ,™ COOK AND § OUT OF HIS 13 NEW: YORK RANGERS say VALET is undentably a better blade OCKEY-—fastest of all sports—calls for steel that takes an edge and holds it. Professional players must know steel. Safety requires it. Success depends on it. That's why their preference for the new Valet blade is noteworthy. Eight out of 13 New York Rangers shave with this blade —made of triple-hardened steel, finished to a micro-edge by automatic machines. The newValetbladeisaremarkabletriumph in steel and manufacturing precision. Dermatologists pescatne it because it glides through beard lightly, without irritating the skin. Try this blade in the scientifically adjusted Valet AutoStrop— the only razor that cleans and strops without removing the blade. You'll like its friendly angle and velvet-like smoothness. AUTOSTROP SAFETY RAZOR CO., INC. 656 First Ave., New York Also Toronto,London, Paris, Milan, Rio de Janeiro All dealers now have the new Valet blade in stock. The NEW VALET AutoStrop BLADE POPULAR SCIENCE MONTHLY APRIL, 1930 Miniature Pirate’s Chest Built to Hold Jewelry By WILLIAM C. CLARK LTHOUGH I A designed this antique look- ing brass-bound chest as a small filing cab- inet to match a desk set I had made, my wife decided it would be much more ap- propriate as a jewel case. So today my filing box graces her dressing table. American black walnut is perhaps the best wood for a chest of this kind; one well-seasoned, straight-grained board 34 by 6 in. by 4 ft. is sufficient. j The brass straps were cut from worn linoleum binding. The end decorations were at one time the lining of a pump cylinder which a plumber sold me for ten cents. This piece was heated to a cherry- red color over a gas burner and allowed to cool gradually so that it would be soft and workable; then it was flattened into a sheet. The two 34-in. hinges, the hasp, and a small lock were obtained for $1.25, and the two 1%-in. handle rings were pur- | chased in a harness shop for ten cents. The trimmings were nailed on with %- and 3%-in. brass escutcheon pins. The tools used were as follows: Saw, Jewel casket of black walnut with handmade brass straps and hardware. ; hammer, small plane, try-square, _ chisels, gouges, drill, bracket saw, files, a sharp knife, and a home- made miter box. The six pieces for the box are cut to the dimensions indicated and carefully squared. The dado and rabbet joints are marked accurately with knife, try-square, and marking gage, and the waste wood is re- moved with a chisel. The joints then are glued and the box clamped together. Do not use any nails or screws. | se naghaarg a cardboard template for the ends and lay it on the middle of one end with the bottom even with the bottom of the box. Trace around the pattern with a sharp pencil; then mark the other end similarly. Clamp the chest in a vise and gouge and plane away the sides to the desired shape. Save the cardboard from which you cut the tem- plate and use it as a gage for applying to the sides as you work them down to the finished profile. If you have what carvers call a ‘“‘quick’”? gouge—a sharply bent gouge—use it in cutting away the wood . under the protruding curve a Hh Fs of the top. Then wrap sandpaper around a dowel ; for smoothing this recess. ENDS CARDBOARD Finish the work with a scraper and sandpaper. i p TEMPLATE : ew Ss was ah ‘ , VIEW HINGES Working drawings of the parts of the box proper, a template for the ends, and views showing the brass work, hinges, and hasp. To separate the lid from the body of the chest, place the box on a flat surface / and with an improvised 7 gage draw a pencil line all around 3% in. above the bottom. Saw to the line and dress the edges with sand- paper. Then use a block plane to make the lid and base fit exactly flush. The first step in prepar- ing the brass work is to cut the cardboard end template into two parts representing the end of the lid and the end of the box, and then lay out and cut patterns for the brass as shown. Transfer the design to the metal by following the edges with a pencil; then scribe them with a scriber ! or sharp awl. Drill holes in the waste metal where necessary to receive the end of a saw

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1930 ne, ls, cet itp 1e- for he nd re- ire Do 7m ice ice all he ite er Apri, 1930 ! blade. Lay the work over a V-notch in the end of a board clamped to your bench and use a jeweler’s saw or a small coping saw for the cutting. Dress the edges with files and emery cloth. Use the finished pieces as patterns for laying out the brass work for the other end. Center punch and drill holes for the escutcheon pins, placing them about 54 in. apart. Then nail on the decorations. T= hinges, which are rectangular when purchased, are filed to the shape illustrated and annealed so that they can be bent to conform to the curve of the lid and the base. The small brass hasp is_ similarly treated. That part of it which goes on the bottom should be sunk flush with the surface and covered with a wide brass strap, to give a more workmanlike appear- ance. The ring projects through a hole cut in the strap. A study of the illustrations will show how the remaining trimmings are applied. The handle rings are hammered slightly D-shaped. A small brass chain prevents the lid from falling too far back. Rubber- headed tacks prevent the bottom from scratching the surface upon which the chest is placed. The next step is to add several hundred years to the age of the chest and give it the appearance of once having been rescued from a burning galleon. Scorch it black here and there with a blowtorch or asmall alcohol lamp. In one or two places let the flame burn wide, shallow depres- sions. Apply judiciously a few scratches and bruises and scrub the whole exterior vigorously wt a stiff wire brush in the direction of the grain. )\ILE the corners and the brass work at a few points. The brass may be roughened by applying acid here and there with a small brush and washing it off with baking soda and water as soon as it has done its work. When the metal is dry, rub it briskly with fine steel wool. Obtain dark paste wood filler, or color natural filler with dark brown tinting color ground in japan, and rub this against the edges of the decorations, wipe off the excess, let the paste dry several days, and then give the chest two or three coats of hot linseed oil thinned one half with turpentine. Rub the wood vigor- ously after each application of the thinned oil. To antique the brass, mix green ground in japan with enough turpentine to make a thick mixture and apply it over all the metal work. Allow this dressing to dry for five or ten minutes and rub it off lightly, allowing the green to remain in the depressions and rough spots. A little dark brown added in the same manner as the green will make the brass look still older. If you desire to line the chest, cut stiff cardboard or thin wood to fit each inside face, pad the pieces with cotton, cover them with silk, and then set in the bot- tom first, put the two opposite sides in place, and finally fit the two end pieces, which will wedge in and hold all the padding. POPULAR SCIENCE MONTHLY 105 A coupon that wins friends Mail it, please Millions of men have sent these coupons in. And 86% of those who make this free 7-day test never return to old shaving methods know that 86%. of the men who make this test are convinced by it—become reg- ular users of Palmolive Shaving Cream. And that is the proof of the pudding. Surely our chances are good of pleasing you. And if we can do that, you will be the first to want to know of it. We asked 1000 men A few years ago men asked why we, makers of outstanding soap products i These 5 unique features. 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. Strong bubbles hold the hairs erect for shaving. Fine after-effects due to palm and olive oil content. PALMOLIVE RADIO HOUR— Broadcast every Wednesday —from 9:30to 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 time — over station WEAF and 39 stations associated with The National Broadcasting Co. 52b3 in other fields, had never made a shaving cream. They told us—1,000 of them— where other preparations failed. They set 2 high goal for us, and our great laboratories responded. Behind them stood 68 years’ experience in soap- making. But it was not easy. The first 129 formulas were rejected . . . finally success came, in a shaving cream based on the olive oil principle— one that embodied five important features exclusive in Palmolive Shaving Cream. Now a test, please Now we ask the courtesy of a test. For we have tried to please you. And we offer to convince you at our own expense. All you risk is a stamp—and a few days’ shaves will do the rest. Will you mail that coupon now, please? ewe we ww ew ww ew wm wm wm eR ww ww ew ww ee ee = i 7 SHAVES FREE | Simply insert your name and address and mail to Palmolive, Dept. M-826, P. O. Box 375, Grand Central Post Office, New York City.

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THIS Copper Lantern is interesting and simple to make. The tools are ball peen hammer, anvil or smooth block of iron, cutting pliers, file, snips, and a GOOD COMPASS

COPPER BRACKET

COMPASS POPULAR SCIENCE MONTHLY APRIL, 1930

Decorative Glow Lights

Lights such as these not only serve to ornament the mantel, but their light will give the entire room a glow of hominess and warmth. By RICHARD GRAVES IMPLICITY of construction and S attractiveness of design make the glow lights or torchéres illustrated a worth while problem for the amateur wood turner. The lathe operations are of the simplest, and the small amount of electrical work required should not prove a stumbling block for anyone. While mahogany or gumwood are among the best suited for the construc- tion, any close-grained wood may be used and finished to suit the individual taste. In making the top it will be necessary to glue a piece of 1-in. pine beneath the As each piece is completed, sand it thoroughly, apply the finish, and polish it while it is still in the lathe. Bore a hole in the center of the base, using a bit of the same diameter as the 2-in. length of threaded pipe that is to be used for the electric cord. Concentric with this, bore in the top surface holes just large enough to receive _a pull-chain electric light socket as shown in the accompanying drawing. The pull-chain of the socket is passed through a }4-in. hole drilled at one side as indicated. Before threading the chain through, it may be removed from the socket mechanism, passed through the hole, and then refastened. It is essential helps! to bore a hole in the toppiece to serve as an air vent.

hardwood block in order to have a large enough surface to attach to the faceplate.

HE Esterbrook compass, although low in cost, does

work well. Itsneedle and lead are always vertical—parallel. No slipping or digging. The

In the construction of the base, however, | the faceplate can be attached directly | to the bottom of the hardwood block.

The shade is made by bending a piece of 834 by 554 in. parchment into 2 cyl- inder having a height of 55 in. and a diameter of 254 in. Paper fasteners can be used to hold the cylinder together. They should be placed so

as j yates cr oo oe radius is precisely determined, i" ‘ae that the prongs come on the inside. <RERNTRET After the shade has been bent to on its beam, before you start. ! Who shape, it can be decorated with Working on a new prin- 3% eA N artist’s colors; or a decalcomania ciple, it’s small in size, yet i 2% ott transfer can be used. In any case we : ; Lu ae the shade should be given a thin makes up to 8-inch circles. — i 1 Py coat of shellac and allowed to dry A worthy addition to even the oe a PINE thoroughly before it is put in place most elaborate tool kit! COLORED [. ” * ne FACE- on the light. i en tote cial 15-WATT / \ § \ {PLATE Insert the shade over the 258-in. et it’s only 50c—at any LAMP——~} | \ \PIECE projection on the base, and fit the stationer’s, or direct from the . - |} top in place, making sure that the Esterbrook Pen Co.,80Cooper \ / S heads of the paper fasteners are S Psciie — PARCHMENT | *, / awe . placed at the back. The shade may treet, Camden, N. J. Sent SHADE + \ / 0 ° be glued fast to the top but not to postpaid on receipt of 50c in ee the bottom, as provision must be bine PINE made for changing the bulb stamps, cash or money order. pane : ging U . ' hire . seen: poe The best decorative results are e Sy ! PIECE obtained if an amberor flame colored \ “ Ye HOLE. bulb is used instead of white. hee A star drill, so called because it Dea has cutting edges radiating from oe the center, is the best tool to use L/ : for drilling concrete, brick, or other 2 / bog —__1.4"4 <1 masonry.. In the absence of this EABROOK = ft a A drill, an ordinary cold chisel will =. SSCs also do thee work iif it is slowly ia Ba = alors The construction of the top and bottom requires the turned between the fingers as it —for a 'arge circle. most elementary of faceplate turning operations. is pounded with a hammer.

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7 www wo wa wa Pe ES OTM CRE OTD OD

AprIL, 1930

Folds of Cloth Safeguard Files in Tool Box EEPING files in good condition—and they are usually much abused tools— is not half so difficult if you provide a holder for them like the one illustrated. Each file is protected by cloth and is readily accessible. The holder is a box 4 in. high, long enough to receive the longest file, and deep enough to accommodate the desired number of files. Two metal rods A are placed parallel to the ends of the box and at about 1% in. from the corners. A piece of cloth having a width equal to the distance between rods A is sewed

STITCHING FILES ARE IN FOLDS Each file is placed in a fold of the cloth and is thus well protected from the other files. on the rods B sa as to have the loops of cloth come within about 1 in. of the bot- tom of the box. Rods B are bent to a loop at each end and slipped on the two rods A. Similar boxes can be used for storing drills, reamers, cutter bits, and many other tools.—K. RENNER. Stand Converts Hose into Garden Sprinkler Y EQUIPPING your garden hose with an adjustable nozzle and the simple standard shown, it is possible to supply a 20 ft. diameter section of your garden with an even, gentle flow of water. The standard, which can be easily made from scrap lumber, has four legs which are spread far apart to insure stead- iness even with high water pressure. The advantage of slow watering is obvious. First, it is not necessary to hold the hose in the hand; second, the hose can be left on until the ground has be- come thoroughly soaked; and _ third, thorough soaking is an essential if the best results in gardening are to be ob- tained.—H. B.

é : — ‘ Fo ee This wooden hose stand can be made from

a few scrap pieces of packing-case lumber. —

POPULAR SCIENCE MONTHLY : 107 Add «Room the bide: Never Planned . . <5

... and end your heating problems for good '

oly, - that prevents colds and sickness. Your walls, draperies, rugs, decora- tions, furniture stay clean twice as long. Silent Automatic can be in- stalled in a few hours... so quickly your home cannot chill. And it may be purchased on the most reason- able of terms.

Clean as a whistle . . . free from the dust and dirt of coal and ashes .- «+ your basement offers endless ~ opportunities for greater home en- joyment when a Silent Automatic is installed.

You not only have room for a real workshop, a cosy den or playroom, an inviting gym... but you and your wife are relieved forever from all the cares and worries of “tending” the furnace. Your own neighbors will tell you all of Silent Automatic advantages... particularly about its remarkable economy in the Spring. Send the coupon for their names... and for complete information. OMATIC THE NOISELESS O/L BURNER (239) Your home is always warm... that uniform, healthful warmth SILENT AUTOMATIC CORPORATION 12001 East Jefferson Avenue Detroit, Michigan Gentlemen: Please mail me booklet “The Intel- ligent Selection of Oil Heat for the — SILE Street

City State

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

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108 ; POPULAR SCIENCE MONTHLY APRIL, 1930

varnish, and enamel finishes for in- ‘ eg A terior woodwork, there are a num- like burning insulation? ...The | ber of special finishes that the amateur poor chap probably never heard of Sir | craftsman can apply. These finishes har- UT why smoke a pipe that smells . a0 , ° : monize with the more modern type of Walter Ralcigh’s favorite smoking mix- wall decoration and make it possible to ture. He doesn’t know there's a tobacco carry out any desired color scheme on so mild and fragrant it gets theO.K. | both walls and woodwork. : . : Three special finishes will be described of er the fussiest p ipe-sniffer. He —a stipple glaze, a gold bronze flat finish, doesn’t know that true mildness needn't | and an antique finish. Before any of them sacrifice body, flavor and “kick.” He can be applied, it is necessary to prepare ? : a foundation of the dominating wall color. doesn't know he can smoke a pipe all This foundation usually consists of so- day long without getting himself orany- | called undercoaters or flat wall paint, and body else all hot and bothered. In other | the number of coats varies with the con- y . . dition of the surface. Twenty-four hours words, he hasn og Sir Walter Raleigh. should be allowed between coats, and Some day he will. Let's hope it's soon. each coat should be sandpapered lightly and dusted clean before the next coat is

How to Take Care of Your Pipe applied. ‘ (Hint No. 4) Don't use a sharp knife to The last undercoat can be stippled, if clean out the carbon. You may cut desired, to produce a pebbled effect. This through the cake and chip the wood. A lot of little “wood spots’’ take away from the sweetness of a pipe. Use a dull knife or reamer. Send for our free book let, ‘“How to Take Care of Your Pipe.”’ Brown & Williamson Tobacco Corpora- tion, Louisville, Kentucky, Dept. 86. ___. ——_—— | SiR WALTER | RALEIGH © Smokin g Tobacco is done by brushing the paint on a small

milder |

The texture of the stipple can be varied by using cloth, chamois, or a stippling brush.

New Finishes for | Woodwork By BERTON ELLIOT

Wood trim can be antiqued by applying a mixture of raw umber and turpentine over a flat paint or an enameled undercoat. ae from the large group of paint, portion of the surface and then working over it with a stippling brush before it has a chance to set. The ends of the brush bristles make tiny indentations in the paint. If a coarse stipple is preferred, a little dry plaster of Paris or whiting should be added to the paint. In applying what is sometimes called the stipple glaze finish, a small amount of painter’s oil color or a special glazing color of the desired shade is thinned with turpentine, flatting oil, or a special glazing liquid and is then spread out on a piece of tin, glass, or board. The stippling may be done with a stippling brush or with a piece of crumpled cloth, chamois, or soft paper. The fineness or coarseness of the textured effect depends upon the stippling method chosen. The brush or wad is moistened with the stipple color and patted on the surface. Considerable variety in the pattern may be obtained by varying the pressure and adding a twisting motion of the hand as the brush or wad is patted over the surface. Ordinarily a very much lighter effect is preferred in finishing woodwork than in wall decoration, and the stipple color is not, as a rule, applied all over the surface. Pleasing results are often obtained by shading from the edges towards the cen- ter. On a door, for instance, the edges of the panel may be done first, when the stippling color has first been picked up; then as the brush or wad-loses its color, the stippling is continued toward the center of the panel, the center being left practically in plain color. Casings and moldings may be treated in the same way, by applying a deeper stippling on the outside edges. To produce a gold bronze flat finish, the final foundation coat is not only stip- pled as it is applied, but some gold bronze powder is patted lightly into the surface and stippled to produce a blended or clouded effect.

© @&.70 fr @ sO OO FED OO OC | a ae Se a ee ee ee ee ae

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930 = PT weer CUO Oe Aprit, 1930 This is best done with a small wad of cotton batting dipped into the bronze. Another special finish that is extensive- ly used at present is antiquing. The back- ground may be of any desired color, either in flat painted finish or an enamel finish built up in the usual way with a flat undercoater and enamel finishing coats. When dry a brown glazing mixture of raw umber thinned with turpentine is brushed on a small part of the surface and, before it reaches the ‘‘setting” point, wiped off with a cloth. A faint trace of the color strikes into the back- ground coating, giving it the mellow, sub- dued effect ordinarily produced by natural ageing. There is another method of antiquing, but it is adapted for use only on unfinished open-grain woods such as oak, walnut, ash, and elm. The wood is stained in the usual way and given an aged appearance by filling the pores of the wood with a gray wood filler. After the filler has been applied and the surface gloss has dis- appeared, it is wiped off with a cloth diagonally across the grain instead of straight across as in ordinary wood fin- ishing. When the filler is thoroughly dry (not less than forty-eight hours should be allowed), thin coats of shellac are applied, followed by a coat of flat-drying varnish or lacquer, or by a waxed finish. Rubber Band Helps Start Nails in Awkward Places AILS can be started in awkward places if they are held firmly against the side of a hammer head with a rubber band in the manner shown. The twisted band serves as a means of holding the nail upright and immediately releases the nail as soon as it is started into the surface of the wood. Place the band over the head of the hammer, give it one complete twist, and place the other end over the claw (see illustration below.) In putting the nail in place, insert it under one section of the cross formed by the rubber, move it toward the center, and then turn it to an upright position. Start the nail with one firm blow of the hammer.—R. G. HoTcuKIss. POSITION OF g FIRST POSITION OF NAIL THIRD AND FINAL 4 SIDE OF POSITION OF NAIL HAMMER (7 ‘ DRIVES ~K THE NAIL S NAIL READY TO ~ BE DRIVEN The three steps in placing the nail between the twists of the '%-in. wire rubber band. POPULAR SCIENCE MONTHLY 109 These Electric Starting Outboard Runabouts Open Even Shallow Waters to Navigation See ~ . Y » | »} , Tilting 2 Lets You Cruise, Hunt, Fish, Race or Explore Regardless of Shoals or Obstructions Johnson Sea-Horse Motors—world’s speed cham- pions—now cogent with special hulls to match. They introduce seamless, waterproof Sealite construction— omeneg strong, lightweightand fast. These Matched Units ave automatically tilting propellers that ride \ safely over logs, rocks and other obstructions in deep water or shallow. Streams and shallow shores where more than half the joy and usefulness of water motor- ing is found are thus open to them. Heading this group of motor boats are the Johnson Aquaflyer Runabouts, electrically started and lighted, steered by awheel from the driving seat, with motors neatly concealed in ahatchin the stern. This new craft fi every desire for a trim, fast, comfortable run- about at a fraction of the cost of inboard motor boats. Johnson Matched Units—$260 to $1065, f. 0. b. factory Other Johnson boats are powered by s fied Sea- Horses either electrically-started or rope-started. The latter are priced as low as $260 complete and are sold on partial payment terms. Write for color-illustrated catalog de luxe. service parts, : com} i 1 parts OHNSON MOTOR CO., 2589 Pershing Rd., Waukegan, Ill - vag, cee n Canada: Canadian Johnson Motor Con Led., Peterboro, Ont World’s Only Manufacturer of Outboard Matched Units and Largest Maker of Out- board Motors. Originator of Water-cooled Underwater Exhaust and Release Charger JOH NSON MATCHED UNITS SEA-HORSESA@,e BOATS New Sea-Horses Electrically Started or Rope-started Choice of electric starting with quai rope-startin rope-startin: —_ ith tamows “Johnson Reloxee” Ch r in larger Sea-Horse motors. In cmaller Sea-Horses new alternate firing produces smoothness and minimum vibration hither- to unknown in this class. Other features include Water-cooled Unde’ Exhaust and Full Pivot Steering. All dealers carry first-aid

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To Play Better Play Safe To get distance, direction, control on the green . . . to improve your form and your score ... try giving support and protection against fa- tigue and strains to the vital but least rugged zone of your body. More and more, thinking men agree with trained athletes in accepting Bauer & Black athletic supporters as essential sport equipment. Not only to guard delicate cords and structures, but to enjoy the snug comfort, security, freedom which make for brilliant performance. The de luxe supporter is Pal. Strong, rubber-cored ribs knit into its light, porous pouch . . . an exclusive pat- ented feature ... provide super- support and matchless comfort, never binding or chafing. Slow to absorb perspiration, soft as new after washing. Supreme quality and economy at a dollar and up. Bike is a simpler, all elastic sup- porter, the choice of coaches, train- ers and athletes for 55 years. Easy to wash ...easy to wear ... easy to buy at 50 cents upward. At all drug- gists and sporting goods dealers. Pal and BIKE (BAUER & BLACK) DIVISION OF THE KENDALL COMPANY Chicago . - New York . . Toronto POPULAR SCIENCE MONTHLY APRIL, 1930 ANY boy who is handy with his jack- knife and a few ordinary tools can easily build the realistic twenty-passenger toy flying boat illustrated. The hull is whittled from a 1% by 2 by 16 in. piece of soft pine, the pontoons from % by % by 4 in. blocks, and the wings from a piece of stock 34 by 334 by 20 in. The wing and pontoons are mounted on the hull with struts made from wooden meat skewers and lollypop sticks. A recess resembling a cockpit is ‘cut in the Hiv to Whittle-a. Toy Seaplane hull, and a thin metal or pasteboard wind- shield is placed in front of it. The two propellers are bent from %4 by 234 in. thin metal blanks; and the motors, made from 1 in. diameter curtain rod, are fastened to the wing struts with brads and glue. ~ Thin metal is used in the construction of the elevator, stabilizer, and rudder unit, the members being riveted together as shown. The ailerons are represented by knife lines.—DoNnaLpD W. CLARK. ee Te STION OF CURTAI : pape iN ae roel iY POLE. IN HULL Jg* f= 35%) | ; ne ok ee 'f o S %. ae h - : Po re ee nS : Sit A : SET STRUTS TABLE or CoLors KNIPE-LINE ' AILERON | ON Be ia Maas Wing and ee :.. Yellow j\.— sCFins, hull, rudders, pon- toons, and prope'lers...Orange V-bottoms, t struts, motors, and insignia..Green Dimensions and details of a twenty-passenger flying boat model. This is the first in a series of designs for the construction of whittled toy reproductions of the most modern types of aircraft. Chucking a Paper Friction in the Lathe EBORING a paper friction generally involves the difficulty of placing the cylinder in the chuck so that it will be centered and will revolve true. This can be ac- then carefuliy tighten the jaws up on the iron flange. While tightening the jaws of the chuck, rotate the arbor slowly with the hands to be sure that the work is well centered and is complished with little trouble, however, by placing the cylinder on an arbor that is a loose fit in the center holes of the flanges. Mount the arbor on the lathe centers and slide the fric- tion up to the open The arbor should be a loose fit in the center hole of the paper friction being chucked. jaws of the chuck; Folded Paper Airplane Explodes on Landing A TOY airplane that will explode and burn when it hits the ground can be made by attaching a large match to the nose of an airplane made -by folding a piece of paper°to form the fuselage and wings. A small nut similar to the kind used on center line of the lathe. Remove the arbor, and the paper fric- tion can be easily bored with the assurance of having the hole absolutely in the center of the , work.— JAMES ELLIS. dry cells is slipped over the stem of the match and allowed to rest against the head. The match is then attached, head out, to the nose of the paper plane with alarge straight pin. . As the plane hits the ground on landing, the weight of the small nut will cause the match to ignite and thus burn the —..., held true to the |! plane.—ROBERT L. SHaw. l ur —- 10 10 — st AQAdAWWWWW WW AD bd De 10 10

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930 ‘ry we we we UNG \y ApriL, 1930 BLUEPRINTS FOR YOUR HOME WORKSHOP each 15 by 22 in. Airplane Models 50. 36-in. Rise-off- Ground Tractor 69. Lindbergh’s Mono- plane (3-ft. fiy- ing) 82. 30-in. Single Stick 86. 35-in. Twin Pusher 87. 30-in. Seaplane 89-90. Bremen (3-ft. flying), 50c 102. Morris Seaplane (record flight 12'4 min.) 104. Tractor (record flight 6,024 ft.) Furniture 1. Sewing Table 2. Smoking Cabinet 3. End Table with Book Trough 5. Kitchen Cabinet 13. Tea Wagon 17. Cedar Chest 18. Telephone Table and Stool 19. Grandfather Clock 20. Flat Top Desk 21. Colonial Desk 24. Gateleg Table 31. Two Sewing Cabi- nets 33. Dining Alcove 36. Rush-Bottom Chair 37. Simple Bookcase 38. Sheraton Table 39. Chest of Drawers 49. Broom Cabinet 60. Welsh Dresser 68 Magazine- Rack Table and Book-Trough Table 70-71. Console Radio Cabinet, 50c 77. Simple Pier Cabi- net and Wall Shelves 78. Treasure Chests 88. Modernistic Stand; Modernistic Bookcase 91. Modern Fold- ing Screens 93. Three Modern Lamps 100. Modernistic Book Ends, Book Shelf, Low Stand 105. Tavern Table and Colonial Mirror Radio Sets 103. One-Tube (battery operated) 42. Three-Stage Am- plifier 43. Four-Tube (battery operated) 54. Five-Tube (battery operated) DOM scrctiiasinavsicsecs (Please print name and address very clearly) eS ASSIST you in your home workshop, PopuULAR SCIENCE MOonrTHLY offers large blueprints containing working drawings of a number of well-tested projects. Each subject can be obtained for 25 cents with the exception of certain designs that require two or three sheets of blueprints and are accordingly 50 or 75 cents as noted below. The blueprints are Popular Science Monthly, 381 Fourth Avenue, New York Send me the blueprint, or blueprints, I have underlined below, for which I inclose.......... IG bs ce ssachence cents. 55. Five-Tube Details 79. Electric 80. Electric High Pow- er Unit — 81. Electric Low Pow- er Unit 97. One-Tube Electric 98. Two-Tube Electric 99. Four-Tube Electric 109. Screen-Grid Set Ship and Coach Models 44-45. Pirate Galley or Felucca, 50c 46-47. Spanish Treasure Galleon, 50c 48. 20-in. Racing Yacht §1-52-53. Clipper— Sovereign of the Seas, 75c 57-58-59. Constitution “es ron- sides’’), 75c 61-62. Viking, 50c 63-64. 29-in. 4 Motor Boat, 5 74-75-76. Santa Maria (18-in. hull), 75c 83-84-85. Mayflower (17%4-in. hull),75c 92. Baltimore Clipper (8 in. long) 94-95-96. Mississippi Steamboat, 75c 106-107. 42-in. Racing Yacht, Sea ea 108. Scenic Half-Model of Barque 110-111-112. Schooner Bluenose, 75c 115-116-117. Concord ‘Stagecoach, 75c Toys 28. Pullman Play Table 56. Birds and Animals 67. Lindbergh’s Plane 72. Colonial Doll’s House 73. Doll’s House Furniture 101. Fire Engine, Sprinkler, Truck, Tractor 113. Lathe, Drill Press, Saw, and Jointer 114. Airplane kpit with Controls Miscellaneous 15. Workbench 26. Baby’s Crib and Play Pen 30. Tool Cabinet, Bor- ing Gage, and Bench Hook 65. Six Simple Block Puzzles Price 25 cents each except where otherwise noted ORDINARY, LATHER This lather-picture (greatly magnified) of pecan shaving cream shows how large, air-filled bub- bles fail to get down to the base of the beard; and how they hold air, instead of water, against the whiskers. ies cx} ‘o, % ms ¢ sy 5 COLGATE LATHER This picture of Colgate lather shows how myriads of tiny, mois- ture-laden bubbles hold water, not air, in direct contact with the base of the beard, thus softening every whisker right where the razor works. Small-Bubble Lather Makes Shaves Last Longer Your razor works closer and smoother... as a trial will prove wie you finish a Colgate shave, rub your fingers over your face—note that you have a closer shave than with ordinary lather—it’s a shave that is bound to last longer. The reason is plain. There’s a vast difference between this new Colgate small-bubble lather and the old- fashioned large-bubble lather. A marked difference in moistening power. The minute you lather up with Colgate’s two things happen: 1—The soap in the lather breaks up the oil film that covers each hair. 2— Billions of tiny, mois- ture-laden bubbles seep down through your beard ..-crowd around each whisker ... soak it soft with water. Instantly your beard gets moist and pliable... limp and lifeless ... scientifically softened right down at the base ... ready for your razor. Thousands of men, after various trials with ordinary lathers, have adopted Colgate’s as supreme. To prove its superiority, mail the coupon below. We will send also, a sample of After-Shave, a new lotion—refresh- ing, delightful ... the perfect shave finale. COLGATE, Dept. M-721,P. O. Box 375, Grand Central Post Office, New York City. Please send me, FREE, the seven-day trial tube of Col- te’s Rapid Shave Cream; also a sample bottle of “After- have.” RE ierkiisniesscinintabiehahippamnnnceson NEI ciignsocconsoqugerincoasoubihanessccide UY noree---seerecrcrecrcesccesceccccescosenecesores SOMGR ccapccccecccoocse scons

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112 POPULAR SCIENCE MONTHLY APRIL, 1930 d

Homemade Lathe for Making Deadeyes By KENNETH KOEHNLEIN \ X"Marks the

Model makers can turn their ship fittings easily and quickly on this miniature homemade lathe.

ee amateur ship model builders find the making of deadeyes and other small fittings a long and tedious task. Excellent models sometimes remain unfinished because of the great number of deadeyes and blocks needed. With the simple lathe illustrated (Fig. 1), enough deadeyes can be turned out in a single evening to complete an elaborate model. The lathe is merely a chuck mounted ~

ay

» uM (

The least A ie rather, the most h ° f 122A GUIDE STRIP FORI/| can do is to keep a Nicholson Slim TAIL BLOCK WORKBENCH

Taper File on hand. It will give him a sure sharp method of repair- ing the damage that may be done by the hidden nail. For sustained speed in any kind of filing you can bank on genuine Nicholson Files. At your hardware or mill supply dealer’s. OLT

;

~ 5

NICHOLSON FILE COMPANY Providence, R.1., U.S.A. FILED OFF NICHOLSON FILES A -FILE FOR - EVERY PURPOSE ee om? -" The lathe can be used for turning, sanding, or 4 Ay fn i, hn A, he Me, Me A, A, Mn, A, Mn, Ml, Mn, Mt, An, Ml, Mn, Ml, A, Mr, Mn, Mn, Mn, Ml. ] drilling by chucking the stock, sander, or drill. nnn eT een

EETH

—

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

Page 115

rsa.) \ dang ers ind ous ain ber the igh gle lel. ted ApriL, 1930 or any other source of power. It can be used for turning capstans, trucks, car- riage wheels, and kegs (Fig. 5), and for sanding small fittings (Fig. 2). By using two blocks as shown in Fig. 6, cannons, taffrails, and the like can be turned out. I use dowel stock for the large dead- eyes and white celluloid knitting needles for the smaller ones and also for blocks. The stock is first chucked. The tail- stock is then set so that the desired length STOCK TOOL REST: 2x TAILS FIG.6 TURNING CANNON NX o7 ao nD 4 o wn Y LATHE | BLOCK FIRST CU 4. a TURNING STEERING WHEEL Cannon and steering wheels can be easily turned by changing the type of tailstock and toolrest. of stock protrudes on the working side. The deadeye is turned to shape by using a small three-cornered file ground to a cutting edge (Fig. 3). It is sanded lightly with a strip of fine sandpaper and turned off the stock. The tailstock is then moved back, the rule on the guide strip (Fig. 1) serving as a gage for length, so that the next deadeye can be turned. After the lanyard holes are laid out with a punch or sharp nail, the deadeye is held in a battery clamp while being drilled (Fig. 4), the drill being held in the chuck. If the chuck is too large to hold a small drill, place the drill in a pin vise, and the vise in the chuck. The steering wheel is made of hard- wood by the method illustrated in Fig. 7. CHUCK STOCK TA foe *- MAIL 7 By moving the tailstock and noting the reading on the scale, any length stock may be cut. on a polishing head, electric drill, motor, POPULAR SCIENCE MONTHLY i 4 eS FOR performance, for y Y beauty, for ease of applica- ; tion there’s just one finish for thousands of folks who know antze | LUSTAQUIK FINISH So look around your home—your guests do—and apply the at Kyanize finish that a close inspection shows is needed. For toys, furniture, woodwork ele) 4 and countless home uses there’s AROUND the new Lustaquik—the new Ky- YOUR } -anize quick drying smooth flowing, | HOME. waterproof enamel in a wide range | 5 ~ four of smart tints and colors. YlLe vA) ed Special Introductory Offer—Just send us one dollar and the name of your favorite paint dealer and obtain a full-pint can of Kyanize Lustaquik Finish, a brush and the new book-in colors—* The Colorful Home.” Mention color desired. Boston Varnish Company 355 Everett Station Boston, Mass.

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1i4 POPULAR SCIENCE MONTHLY

To introduve a sample of Goodell- Pratt quality to every tool lover in America, we are offering at the special, low price of $1.00, this handy tool. Ideal for repair work on radios, fire-arms, clocks, household appliances, etc. Contains three screw driver blades and reamer. When not in use, the chuck and blades are inside as shown. Nickel plated handle. Satisfaction unconditionally guaranteed. Pin dollar bill to this coupon and send in today. j Sf j Y { y. f

APRIL, 1930

L-PRATT CO., GREENFIELD, Mass.

' GOODEL ' , | Attached is one dollar for one of your pocket screw driver sets as | offered in April Popular Science magazine. | CE ees cckbdabak sans eeccanenvepane es | il aah di hitinh dh nee Ad CROWS EOS ORG | i) cols tcdcemhenseaewe RN. atliiwtaalens y My hardware dealer is. ...........60-.-eeeeeeee oesdaces

MODEL SHIPS | | ie... BAND SAW

We can supply construction sets and all sorts of parte such as semi-finished hulls, blocks. For commercial shop or home jeadeyes, spec flags, anchors, steering - ry wheels, capstans, figureheads, blue print work shop—a heavy duty pre- books, ete., for building real fine scale models cision tool; rtable, motor- of the Flying Cloud, Constitution, Spanish driven, reasonably priced. Does Galleon, Mississippi River Steamboat. Sover- speedy and accurate work. eign of the Seas, Bluenose. Mayflower and Write for attractive price of- | sides of the switch. the device is ready for use.—H. H. Ruae.

many others. Also special construction sets for racing sail boats, f maged boats, model eam, engines, propellers, etc.. a uae —_ er. ‘or the model maker. Our large 48-page photographically illustrate HESTON & ANDERSON els in addition to prices and ful lescription of the above articles < n! Many people only slightly interested in models have become 804 Kirkwood Ave. Fairfield, lowa

greatly enthused upon receiving this booklet. A copy will be sent postpaid upon receipt of 15 cts. (coin preferred). Model Ship Supply Co., Dept. O, Mineola, N.Y.

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

SPARE TIME WORTH $1.00 PER HOUR Others do it. So can you. A modest equipment of Boice-Crane machines installed in basement or garage workshop will make your spare hours worth money. Mr. M. W. Cusarna, Fitchburg, Mass. even claims an average of $2.00 per hour for his spare time. Mr. W. L. Muir, Olympia, Wash. makes $1.00 per hour in his time at home. Mr. Frank WHITAKER, paying his way at college, sold 23rd ship model for $125.00, his 24th will sell for $75.00. W. H. Durer, Marquette, Mich., though in poor health, supports a family of four in basement shop, earning as high as $25.00 per day. Earnings from spare Tables 20-inch. Planes 1/4 inch x 4 inches, time easily meet monthly payments. Fence tilts 45 deg. both ways. Bronze bear- ings. , Uagroved rabbet arm. Safety $25 6’ Handi-Jointer $75

4 Handi- Jointer

Han- disaw

inch saw cuts 2°. Elevates for dadoing. Attachments for oe SS. disc and drum sanding. boring. ing. grind. 0

Jig Saw Table 8-inch diameter. A variety of lathes, Priced, $13.50 up

Send 10c for 80 page catalog describing Boice- ngs. Crane Circular Saws; Jig Saws; Lathes; 4-inch, § 6-inch Jointers. Let us tell you how to turn 8 spare hours into money. t motor} W.B. &J.E. BOICE @ +] s 10

ches. Capacity 10 in. to frame. 600 R. P. Dept. P. S. 4-F M. i Of bladeod LZ Toledo _ Oh

| of the Spirit of St. Louis.

Bringing Wall Switches within Child’s Reach del wall switches are too high for a small child to reach. A very simple and at the same time convenient method of bringing these switches to a lower level is shown in the illustration. An advantage of this arrangement is that the walls are in no way disfigured, and the device can be removed when it is no longer required. The switch plate and switch should first be removed and a single flush outlet receptacle installed in its place. This is an easy change to make, since the two devices are mounted in exact- ly the same man- ner. Make up a short extension cord consisting of an 18-in. length of silk covered, parallel conductor lamp cord and an at- tachment plug and a small pend- ant switch. A through type switch may be used instead of the pendant switch shown in the illustra- tion. In this case, the hole in one end of the switch body only is used, and the two wire ends are connected to the opposite Pendant switch, plug, and wall receptacle form the extension. Insert the plug in the new wall outlet and Model Plane Flies Too Fast for His Camera NOWING that there are many who would enjoy seeing the products of other readers’ skill, Mr. Claire Wilson, of Calgary, Alberta, Canada, sent in the photograph below of his completed model In his letter Mr. Wilson said: ‘‘I was unable to get pictures of the model in flight, as I found that it flew too swiftly for the type of camera that I used. I found this model to be an excellent per- former for its weight and size, and secured flights from 90 to 250 ft. when hand launched and also realistic R. O. G. flights of smaller distances. I found your blueprints very easy to follow.” Many excellent airplane models are in- cluded in our list of blueprints on page 111. These include a very light scale model of the Bremen (No. 87) and two noteworthy long-distance models (Nos. 102 and 104).

The model was built from Poputar ScIENCE MonrTHiy Blueprint No. 69 (see page 111).

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

f

Page 117

1930 for ery ent oa on. hat the uld let ; is the are ct- in- ort rd an ilk lel np at- ug d- De be he “ of vO ite nd el Apriz, 1930 POPULAR SCIENCE MONTHLY Turning Heavy Pipe in a Small Lathe [X CONSTRUCTING a large dam in India it was necessary to machine a large pipe bend so that it could be used as part of the sluice valve piping.. Such a bend should be turned on a large lathe, but since none was available it was a case of doing the best with the machines at hand. As in many cases ingenuity took the place of proper facilities. First, the bend was attached to the cross slide of the lathe by means of a Cross-feed is obtained by having a pawl en- gage a ratchet wheel on the compound rest. 5g-in. wire clamp, thus allowing the depth of cut to be adjusted. A compound rest was bolted to the faceplate and a counterbalance arranged in order to insure smooth running. An L-shaped boring bar was adjusted on the compound rest and an arrangement for cross-feed was made by placing a ratchet wheel in place of the feed handle. On the head of the lathe can be seen a bracket which holds the pawl; this in turn engages the ratchet once every revolution and thus supplies the necessary cross- feed.—R. J. Soman and D. G. SurRnis. Accurate Jointing with Hand Plane and Guide A CURATE jointing or edge planing of thin stock can be accomplished easily by clamping a hand plane and wooden guide in a bench vise as shown. Sharpen the plane iron to a razor edge and set it to take a very light cut. Then make a guide from a sound piece of stock and on the back of this nail a second piece about 5 in. wide, placing it so it will pro- ject 3% in. below the lower edge of the first piece. Fit the guide on the plane as shown and lock it in the vise, making sure that the fence is at right angles to the bottom of the plane. Hold the work edge up, press it firmly against the fence, and slide it over the cutter.—W. C. L. The guide is placed against the plane and the whole is held firmly in a vise. Here you are, Gentlemen! nother Opportunity to try the Williams Shaving Service ood news... for every man! For a short time, with every tube of Williams Shaving Cream —large size—at the regular price, 35 cents, you will receive, FREE, a bottle of Aqua Velva, half the regular 50-cent size. A chance to try the Williams Shaving Service, with half of it for nothing! Velvet! . . . forthose who know this shaving service. Velvet! ... for those who do not know it yet, but who, once they do know it, will come back and buy. That’s why we offer it. No face has learned the utmost in shaving care and comfort that has not known the Williams Shaving Service—Williams Shaving Cream and Aqua Velva. And here’s a chance—a short-time chance with long-time comfort—to get half of it FREE. . § oa The Williams lather, Standard for 90 years. Lather that makes for quick shaves and clear complexions. And Aqua Velva, a perfect after-shaving preparation, made to keep the skin all day long as the Williams lather leaves it, flexible and Fit. This combination of Shaving Cream and Free Aqua Velva is on sale wherever shaving cream is sold. Don’t miss it, (This offer is good only in the United States) THE J. B. WILLIAMS COMPANY, GLASTONBURY, CONN.—MONTREAL, CANADA JUST NOTICE THE FINE SKINS OF MEN WHO USE Williams SHAVING CREAM——AQUA VELVA 115 | = : 7 = eee Sa i ee oe

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i f | f ;

116

Wa

Dampness and flooding from ground water getting in is easily stopped by

fous spots in concrete or brick walls and floor with SMOOTH-ON NO. 7 —the only effective waterproofing material that can be applied from inside and to wet or dry surface. Excellent also for waterproofing boiler pits, cisterns, tanks, ponds, wash-room, garage, and stable floors, etc. About 25 lbs. required for each 100 sq. ft. of surface and you can do the work yourself. SMOOTH-ON No. 1 is the good old standby for stopping leaks in

steam, water, gas, oil, or stove pipes; mend- | ing cracks, breaks or leaks in furnaces and boilers, radiators, tanks, sinks, pots, and ee making loose handles tight on umbrel- s, knives, hammers, brushes, drawers, etc. ; tightening loose screws, hooks, locks, door knobs, etc. Use it on the automobile for stopping leaks in radiator, hoseconnections, gas tank, gas, oil and exhaust lines, keeping lubricators, hub caps and nuts from loosen- ing and falling off, etc. The Free Smooth-On Re- pair Book will show you how an astonishing num- ber of repairs are easy to make, and by doing the work yourself you make big savings. Mail the coupon for a free copy.

Write for FREE BOOK Get Smooth-On No. 7 in 1 or 5-lb. can, or 25 or 100-lb. keg and Smooth-On No. 1 in 7-oz. or 1 or 5-lb. can. At any hardware store, or if necessary from us di- rect.

SMOOTH-ON MPG. CO., Dept. 58, 574 Communipaw Ave., Jersey City, N. J. Please send the free Smooth-On Repair Book. Return this coupon for a FREE copy of Booklet

filling the cracks and | painting over the po- | POPULAR SCIENCE MONTHLY

Hints on Building |” Your Eye Sees It~ a Game Table N BUILDING a small-size pool table (such as the type described in P.S.M., Mar. ’29, p. 124), a few simple kinks can be applied that will not only simplify the construction but make the work more nearly perfect. Small size billiard balls are hard to ob- | tain and when they are obtainable are expensive. Imitation agate marbles, how- ever, serve nicely. They come in many colors, are just about the right weight,

Imitation agate marbles, “% in. in diameter and of different colors can be used as balls. have the necessary life, and a whole set of these marbles, '3¢ in. in diameter, can be purchased for thirty-five cents. Three- and four-bank shots are possible if 34-in. chemistry hose is used for cush- ions. Glue the hose in a groove cut in the sides of the table. The soft pliable rubber is preferred to the harder, reénforced | variety. Pockets can be easily made by using a piece of brown kid leather as shown in the figure at the top of the following page. The leather is cut as shown and fitted around a small piece of 34-in. dowel. By allowing the edges of the leather to over- lap a little, stitching the joint will be unnecessary. Cues can be made from a 1 by 6in. by 3 _ CUE JIG BROWN KID LEATHER (SLITTED AS SHOWN) xz

iF AF + | TABLE POCKET

Zz

“BOTTOM EDGE oar ES * = Dimensions of the jig for holding the cue blanks and method of making the pockets. We

APRIL, 1930

WOLLENSAK MICROSCOPE 16.93 0 OLVE the mysteries of insect, plant and mineral life with the Wollensak Microscope. Reveal to yourself the beauties of nature hidden from _ the unaided eye. One of these fine micro- scopes should belong to every student dentist, physician, or scientist an should be part of the equipment of home, office, school, or laboratory. I¢ gives a range of magnifications from 100 to 250 diameters in steps of 25. Elabo- rately finished tilting stand, nickel trim, plush lined case, pre ared slide, com- plete instructions. Ask your deaier, or, we will send you one postpaid. Money back guarantee. Lower powered Wollen- sak models $2.50 to $8.50. Catalog free. WOLLENSAK OPTICAL COMPANY 871 Hudson Avenue Rochester, N.Y. DANISH INVENTOR BRINGS YOU AERFECT SHAVES

Albert E. Freidrich of Copenhagen. Denmark, tired of pnensistostery shav- ing > ing met to do away with razor blade troubles. Fi pers’ and * ‘sharpeners”’ unsatisfactory and safety razor blades costly, seperteentes for years and finally produced the solution to shaving trou! This is sie Bello Hollow Grinder—a precision machine that grinds two new concave shaving edges on Gillette blades in a jiffy, gives smoother, keener shaves and makes one blade give months of the best shaves you ever Bello is poratbecccneot for a lifetime—nothing to get out of order. Try It At Our Expense Send the coupon for a free ten day trial a this. amazing invention. Learn what shaving pater, really is. We'M alsé send you the razor feloth that suves§the family towel. Bello Corp., Dept. PS$4, Gardner, Mass. Send me Bello for 10 day free trial, also my razor cloth. DOF OAD Bicdcceccccicccccceccccssscccdscccscesedéecccecocssoesas By address is wcccccsccccccecesccsce occcesrecesececesccosoceces St. CHA cccccccccccceccrescces -MABcccccccccecserece im] Check here for tested am, making Doe Ree cannccdccecadececbccsicncess plans for acents.

Andy! Sannelia Talks to Reed Players. Get this Free Book! On the air tonight, and every night, Andy Sannella is earning a fabulous salary with his Selmer Sax. In his book of ‘‘Advice to Saxophone Players,’’ he gives more valuable information than in ten private lessons. This SS Book also book also ay my Talks to sts by Alexan vey Send for free copy. Ifyou will mention the instru- Es —_ eo play, we will send ee samples of our . They t

a yh Dey ~ BUILDING, ELKHART, INDIANA (In _— 10 Shuter St., Toronto)

val of |

TI th is < whe side can plu; The wit an afte The an j gag a te Thi suff be pro

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930 a ak A fi 'faead Aprit, 1930 ft. 3 in. piece of well-seasoned maple. Smooth and straighten one side, turn the piece over and plane the opposite side to a taper, so that the piece measures 7% in. on one end and 3 in. on the other. #ip the | piece down so that it will be 74 in. square | on one end and 3 in. square on the other. | Plane off the four corners thus giving you an eight-sided piece. Continue the process of planing off the corners in this manner, holding the blank in a wooden jig such as is shown in figure at the top of the following page. This jig can be held firmly in a vise dur- ing the planing operation. In the making of small-size cues the difficulty of obiaining tips small enough for use has always presented a problem. A serviceable tip can be made by driving y-in. rubber-headed tacks into the tip ends of the cues and grinding them down to size. These tips have the added ad- vantages of not coming loose easily and of being easily replaced.—G. A. REIMER. Jars under Shelf Hold Hardware Y SUSPENDING mayonnaise jars under your workshop shelves as shown, you can save space and at the same time keep screws, bolts, lock washers, and various spare parts in full view. One twist of the jar will free it from its cover, and a like twist in the other direc- tion will fasten it back in place. The jars used are of the screw type having a tin cap. The caps are attached to the underside of the shelf with three screws and should be spaced so that there The caps are fastened to the underside of the shelf. is at least 1 in. clear between the jars when they are in place.—W. L. Fauror. Stopping a Leak in a Hot Water Tank Vy Ren a hot water storage tank de- velopsa leak, most householders con- sider it beyond repair. But a small leak can be stopped easily by driving a tapered plug of white pine or walnut into the hole. The plug should have a very gradual taper with the entering end almost as sharp as aneedle. It is driven in with a hammer after it has first been soaked in water. The projecting end is cut off within half an inch from the tank surface. A leak in a tank made of extra heavy gage metal may be repaired by driving a tapered steel punch through the hole. This turns the metal inward and forms sufficient surface so that the hole may be threaded. Inserting a screw of the proper size will stop the leak. POPULAR SCIENCE MONTHLY 117 4 of i In this well-equipped home workshop, Mr. W. C. Miles, San Ber- nardino, Cal., uses many ATKINS Silver Steel SAWS, including circular, band, and several types of hand saws. ECAUSE “‘Silver Steel,” the world-famous saw steel which is used exclusively by ATKINS, makes these saws cut faster, easier, hold their keen tooth-edge longer, and outlast ordinary saws! That’s why thousands of home-craftsmen use the small sizes of ATKINS Circular Saws and Band Saws—just as great lumber mills and wood-working shops everywhere use the larger 81zes. For ripping, cross-cutting or mitering in your home -shop—do the work quicker, smoother 2nd better with ATKINS Circular Saws! Sizes for your electrically-driven hand or bench machines! Also, Dado Heads, and combination novelty saws. For the band saw machine you have or may buy, you can get ATKINS Narrow Band Saws to do faster, finer cutting. Widths from 14” to 134”; any length! And you get this same ‘‘Silver Steel’ in scores of other ATKINS Saws and Cutting Tools for your shop. Hand Saws in wide variety . . . Hack Saw Frames with the new Silver Steel Blades to cut any metal speedier and easier. . . Back Saws... Compass Saws... Keyhole Saws. . . Coping Saws... Files and Saws Sets. . . Scraper Blades . . . Machine Knives for your planers, jointers, mortisers, etc. See the ATKINS Saws you want, at your Hardware Store! Write us for the four helpful saw booklets offered FREE below! -— Send coupon for these FREE Booklets = oe oe ae oe ee oe ee —_— = E. C. ATKINS & CO. |} Est. 1857 _ 428 S. Illinois St. | INDIANAPOLIS, IND. } Please send me the four Saw Booklets | FREE. SILVER-STEEL SAWS ATKINS CIRCULAR SAWS Circular Rip, ut = Mitre Saws for Rn an work on any ATKINS GROOVER OR DADO HEADS The simple, easy way to cu’ even grooves from %’ to 4’ ATKINS No.401 HAND SAW ‘ pa t snooth width. ATKINS “400” and “401” are the finest Hand Saws made. Silver Steel Blades. ‘ection Handles—no wrist strain. No2 BACK Every home-sh op or tool kit needs this back Saw for fine work. Bagi er Blade lengths. id Silver Steel ; 8 to 18 in. ATKINS No10 Nickeled steel adjustable frame, pistol grip handle; Non- Breakable Z the New Silver Stee! Blue-End A handy saw for fees =r Boy Scouts; blade, Cherry esa © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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118

— More Shaves per blade (and | mean good ones) That's my Guarantee. fim tony oe the guarantee above. It’s a sporting proposition to every man who doesn’t use Mennen Shav- ing Cream: Get a tube of Mennen. Then slip a new blade in the old razor and use it day after day, until the blade begins to drag. Countup the shaves... Two more - blade with Mennen, or send me ack the tube and I’// refund your money. And I hope you doubt me...then I get my chance to prove it. Two more shaves per blade aren’t so im- ortant — perhaps—but how much tter each shave must be when I can make a guarantee like this! Better shaves—that’s the point about Mennen. Your face feels the difference the first day — cooler — cleaner—more comfortable. Special Note: Rather have a free trial tube to check me up with? All right. See the coupon. Clip it out and shoot it in. MENNSN SHAVING CREAMS MENTHOL-ICED AND WITHOUT MENTHOL

I'll take Jim Henry up on those 2 More Shaves per Blade. Start the trial tube my way.

City 0 Send me Mennen Menthol-Iced 0 Send me Mennen without Menthol

POPULAR SCIENCE MONTHLY

THE SHIPSHAPE HOME Electric Fittings Designed to Do Double Duty ' N YITH the new and improved light- ing fixtures, switches, bells, plugs, and various appliances now on the market, it is an easy matter to add to the electrical conveniences of your home. The accessories, for the most part, are simply installed, and each has some special feature and ofttn does double duty. What wall fixtures are best suited for bathroom, kitchen, and washroom in- stallations? The latest wall fixtures for this use are made of solid porcelain. These fixtures,

Modern bathroom and kitchen wall fix- ture with extra appliance receptacle. besides being practically indestructible, can be easily cleaned, and they reduce the danger of accidental shock in case of a short circuit or defect in the socket mech- anism. One type of fixture has incor- porated in it an appliance receptacle for connecting a heater, curling iron, or other apparatus. (See the accompanying illustrations.) A novel switch in the form of a pend- ant is also a part of the new fixture. . Can conduit in- stallations be made without do- ing much pipe fitting and threading?

Yes. Thread- less fittings (see illustration at top of page 119) are offered by several manufacturers. With these new conduit fittings, it is no longer necessary to cut threads on the ends of the pipe. The con- duit is cut to the desired length, inserted into the fitting, and held firmly in place with one turn of the nut. This turned off and on by a knob under the socket. wall light is

For the Home.Work shop, or Manual Training With this 500, 1b. capacity _Simplex Jack, you can straighten window or door frames and _ avoid planing or resetting locks—level radiators, plumbing, drain pipes, ice box; straighten or clamp glued work, radio cabinets, stretch shoes, etc. This little ‘Jack in the Box’’ is for the man who uses tools, or the boys inter- ested in manual train- ay be mechanical toys. It has hundreds of uses. Sturdily built, beautifully finished and un- conditionally guaranteed. Its purpose is to demonstrate and advertise the exclusive safety feature of the visible screw and power of the large Simplex Jacks, and will be sent you prepaid for cents—Canada 45 cents. Money refunded without question and instantly if not

satisfied. #4 & Templeton,Kenly & Co. 1740 | ae ESTABLISHED 1899 nema ¢ | 1020 So. Central Ay Chicago Il. 4° exe lemen: eune send tae Sits ey Miniature Jack at $6 Conta and at Sb cents A total of $__is enclosed.

—_—-— -— es Ask your Hardware dealer for the larger Simplex Jacks

Get Into Business This 7 Machines in One! Sent you for FREE Trial on deposit of A whole year to pay. The Electric Carpenter Make money on screens, trellises, furniture, toys etc. 8-in. Circular Saw; 14-in. Band Saw; 36-in. Lathe, 10-in. swing; 6-in. Jointer; Reversible Shaper; 4-in. Hollow Chisel Mortiser; Sander. Does 35 Woodwork- ing operations. NOT a toy. Write Today for Illustrated Folder We also build a complete line of single-purpose machines The Woodworking Machinery Co., Inc. 258 N. Eleventh St. Phila., Pa. nxO Tye Lubricates PRIEND Polishes

Ball Bearing Throughout Weight 520 lbs.

Prevents rust finest oil for protection of a tools and all small ma- OAs ) chinery. Never gums or eC tbe hardens. Colorless, odor- 1 less, stainless. A Send direct if 3 5c your dealer cannot supply.

PLE, | Wm. F. Nye, Inc., Dept. R. New Bedford, Mass. Oil refiners for nearly a century

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

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if -~_-— HL = i 4 | ring hout ) lbs. toys athe, 4-in. work- st n of ma- ; or dor- Apri, 1930 NEW THREADLESS FITTING FOR CONDUITS As the nut is tightened it forces the teeth on the compression washer into the surface of the pipe. Is there a wall plate combination that includes a toggle switch and an ap- pliance receptacle? Where a switch and a receptacle for a plug are needed, a neat combination of the two can be obtained to fit into a single unit wall box. The switch may be used to control a light, and the receptacle made to operate separately; or the switch may be so connected that it will be possible to turn off the appliance with the switch instead of by the usual method of remov- ing the plug. (See illustration below.) What is the best method for lengthen- ing a lamp cord that is too short? Lengthening a lamp or extension cord with the aid of a taped joint is prohibited ORDINARY A COMBINATION SWITCH AND RECEPTACLE UNDER ONE SINGLE PLATE CORD CORD o> PLUG — EXTENSION A new combined toggle switch and receptacle and the method of using a lamp-cord connector. by wiring inspectors. The correct way | to extend such a cord is by the use of a | connector such as is shown in the illus- tration above. The desired length of wire is fitted at one end with an ordinary plug, and at the other end with a cord connector. The advantage of this method, aside from the fact that it is safer, is that the extension may be used on other lamps or appliances. Can a combination buzzer and bell be | obtained for use on the front and back | doors? A new combination, which includes a bell and a buzzer, is now on the market. The entire installation is no larger than an ordinary bell and is just as easy to connect. The wiring diagram is shown below.—HaroLpD STRAND. BUZZER TERMINALS WITH CONTACTS -FIBER WASHERS REAR NO WASHERS © BUTTON INSIDE VIEW OF COMBINATION, v TERMINAL NOT INSULATED GOES TO an BATTERY OTHER TWO CONNECT TO PUSH BUTTONS Diagram showing simplicity and compactness of the combined doorbell and buzzer unit. POPULAR SCIENCE MONTHLY 119 AMAZING STUNT proves Gripping Power of NON-SKID Screw Driver lhe RIBBED BLADE Frevenls Slipping EEMS almost miraculous! Yet it’s true! A Bridgeport Non-Skid Screw Driver was in- serted in the slot of one of the screws holding the license plate, and, with a firm turning pressure to bind the blade in the slot, the car was actually pulled! The Non-Skid Screw Driver grips the screw like a non-skid tire grips the road. Drives screws easier, quicker, safer. No pushing — you need only turn the Non-Skid. Grips battered and rust- ed screws as though they were new. Grips greasy screws that smooth blades merely “skate” off. The point lasts longer because it doesn’t slip. 3 STYLES Mechanics, carpenters and electricians are say- ing good-bye forever to “skidding” screw Sizes drivers! Use the Non-Skid once, and you, too, will be “off” smooth blades for life! Ask your dealer today to show you the new Bridgeport Non-Skid. Try it before you buy— MP gg clear on the screws in his Non-Skid demonstration through handle. ““The block. If your dealer is not yet supplied, order direct: No. 1—4”", 50¢; 6”, 60¢. No. 2—4”, 35¢; 6”, 45¢. No. 3—4%", 45¢; 6%", 55¢. THE BRIDGEPORT HDWE. MFG. CORP. Bridgeport, Connecticut The World’s Largest Makers of Screw Drivers TRAOE geport THE CHOICE of MEN WHO KNOW TOOLS finest screw driver I ever owned,” say t ics and carpenters. No, 2 secure- ly together. The best screw driver at its price. No. 3 Shock-proof up to 18,000 volts. i for electrical and cab- inet work. Slim blade with magnetized point. Orthis seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE CF STANDARDS. See page 8.

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Build it with a MAYDOLE Balance, strength and a stubborn resistance to wear are built into these Maydole hammers for the home workshop. Take one in your hand, heft it, swing it... you'll know instantly it’s the kind of a hammer you’ve always wanted. Made from high grade tool steel and selected second growth hick- ory, the face and sides have just enough crown to prevent marring the work and the claws of the nail hammer will pull the smallest brad or largest nail without slip- ping. Your dealer carries them, ask _ to show you the weights you ike. Please send me a free copy of Pocket Handbook 23B which contains many valuable tables and much useful information. ae deel 5 eae ee dnt ee hee ie di es alee may HAMM rv ole Hawones The David Maydole Hammer Co., Norwich, ay. © POPULAR SCIENCE MONTHLY Easy Method for Bending Large Diameter Conduit NDUIT between 2 and 3 in. in diameter can be bent neatly with the aid of two heavy beams and two cross- pieces bolted together as shown. The position of the crosspieces is determined by how far the bend is to be from the | The bending frame can be rested on a sawhorse. a “a end of the conduit, and a number of bolt holes can be bored to allow adjustments to be made quickly. The crosspieces should be of reasonably soft wood and | care should be taken to do the bending | cautiously to avoid kinking the conduit. | Simple Tool Facilitates | the Driving of Nails | fpeere can be easily driven in awk- ward places if the simple tool illus- @ DRILL ROD trated is used. TO FIT INSIDE OF TUBE sists of a brass tube about 8 in. | long inside of which is placed a piece of drill rod having the same outside diameter as the Ufc inside of the tube. of; ND OF ROD The end of this rod is magnetized - and serves to hold the nail in place, thus allowing the nail to be driven in awkward places. Useful Tool Made from Discarded Calipers WwW the expenditure of little time and trouble it is possible to convert a pair of inside iron calipers into a very handy measuring tool. Heat the ends of the inside calipers and bend them so the points point in as shown in the illustration. These points can then be trued up with a file and the tool is ready for use. These calipers can ] BRASS TUBE The magnetized rod holds the nail in place. be used in check- ing to see whether certain distances are equal, whether holes are equally spaced, and in doing many other odd jobs that are always bound to present themselves in machine The points are bent in and are then filed true. It Easily Pays for Itself The tool con- |_ shop work.—J. C. F. APRIL, 1930 Here is everything your ae to re. ed crea- tive instinct. MAC R ME- CHANIC isa real Sahin phn +s - -~ Ba - finished products unexcelled in quality. Used in schools, factories and carpenter shops for most difficult woodcraft operations. Even in unskilled hands results are marvelous. Comparison with other outfits will quickly prove its superiority. That’s why AT x offer the MAC on 10 days’ IALwith absolute guarantee of satisfaction or no sale. inetmuctions in woodcraft are furnished FREE. yi Experience the thrill ¢ mak- H| ing things from wood. Send 25 cents today for 24 plans with complete instructions for mak- ing such articles as a Grand- father’s Clock, Book Case, Tables, Ship Model and many other useful articles. These plans easily worth $2.50 — sent for only 25 cents if you order now! Write for Complete Details Send now forliterature ce Uinetracion a describing MAC —THE POPULAR Workshop — details of our FREE TRI Rr’ Offer, also liberal monthly terms. MIDLAND APPLIANCE SS on S.. 225 No. Michigan Ave. Free Plan Tells You How To Make Extra Money In Spare Time Start your own busi- ness filing saws on the : Foley Automatic Saw gq oo in spare time, and ‘ ou will soon have a q fine paying | of a your own. is : work- Big Pret. its. Very small gee S investment makes big mon- “Tl ey. Simple to operate—business ener 40 get. Get started NOW Send for Free Plan. Foley Mfg.Co. ifmairstcin? ; ee! wu ‘/ FREE! Large 6-foot air bag with inflators, para- chute and com em instructions for flying. Send name and we'll send 6 of our new re- = of ———— ro eames: ee to ig of onspeci offer 50you. oaliest and for thisservice we will send this wonderful — with instructions free. C.M.THOMAS, 337 W. Madison St. 4 K 46 a RR -wh FORMS TO ones LEAD SOLDIERS INDIANS, TRAPPERS, Hunters, Wild and Farm Animals. 222 2 Wonderful ‘ “True to Life’® models. sy and inexpensive to make. he gu all necessary material. Send 5c Stamp f for Illustrated Catal Henry C. Schiercke, 1034-72nd St., pre N. Y. Complete 110-volt Electric ELECTRIC Bettie teal den ANY WHERE #139 Runs household popteneces. Install it yourself, Wiring, Fixtures and Lamps for 7 fooms, $17.50. Also larger models D. C. or A. C. Write for circular-D. Ww. ONAN & SONS 306 Reyalston Mi Mina. This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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rea- AE- rin d 4 10st lled vith ity. ays’ itee ons SS SS LF "Ome F351 Xe Apri, 1930 Sewing Stand Has Two Handy Trays and a Workbag SS providing ample space for sewing equipment, the convenient, lightweight, sewing stand illustrated also has a deep bag for unfinished work. While the design is based on a segment of a circle, the construction should not be difficult for the home craftsman. If the pieces are accurately cut to shape, the assembling opera- ‘ tions are not much | more complicated | am than in rectangular 1é work. W/Z Mahogany, red & gum, birch, maple, or cherry will serve IL well for the frame- =F work and top, but | _ almost any wood og may be used in the construction if a painted or lacquered finish is preferred. Get out the four legs, each 134 by 134 in. by 2 ft. 1 in., and taper them to 7 in. square at the bottom. This taper should begin 314 in. from the top. Make the 34 by 3 by 8% in. side rails A and fit them to the legs with three 34-in. dowels. The curved front and back rails can be band sawed from a piece of stock 3 by 3% by 16in. Sandpaper the straight rails and the legs and then glue each end of the stand as shown in the diagram on page 122 under the heading “‘first gluing.” Draw a full size top view of the legs, rails, and top. Place each pair of legs in Two hinged flaps form the covers. ‘| position and dowel-joint the curved rails. Try the pieces together and make two forms such as B from 1-in. stock. After a good fit is obtained, take the pieces apart, sandpaper the curved rails, apply glue, and clamp as indicated in the diagram marked ‘ ‘second gluing.” Besure that the outside corners of the legs are parallel. Square up the top of the assembly by bracing it until the diagonals are equal. The two sidepieces C of the frame for STRAPS } }} \ COVERED PASTE BOARD > a hd it E = +, 0 i so HINGE i | LEAF 2 WORK BAG TT "BitK) K—e—= ; i Les I ul The design for the top is based on a segment of a circle. Note the leg and rail construction. POPULAR SCIENCE MONTHLY 121 RYAN AIRCRAFT CORPORATION LOCKHEED AIRCRAFT CORPORATION PARKS AIR COLLEGE, INCORPORATED PARKS AIRCRAFT CORPORATION EASTMAN AIRCRAFT CORPORATION AIRCRAFT DEVELOPMENT CORPORATION The First Step in Flying— THE DETROIT GULL Aviation experts agree that gliding offers the most satisfactory method of air training preliminary to motored flight. This fasci- nating and instructive sport is rapidly becoming popular. Gliders, Inc.y a division of Detroit Aircraft and builders of the Detroit Gull, are the pioneer manufacturers of taotorless aircraft in the United States. The Detroit Gull is the result of 18 months of intensive engineering research and flight tests—and incorporates only proved principles of design. The Detroit Gull is used by gliding clubs throughout the country. Their records have established that it costs practically nothing for upkeep. As high as 800 flights have been made with only minor expenses for repairs. Inexpen- sive, gliding is also thoroughly safe. Sturdy in construction, the Primary Type Detroit Gull is built to stand hard usage. The wing span measures 34 ft. and the length overall 17ft.,7 in. The Detroit Gull is popularly priced at $435, complete with launching rope and safety belt. Why not form a glider club in your vicinity and en- joy this thrilling sport? Write today for our illustrated folder and com- plete information. DETROIT AIRCRAFT = srasreatiscomnn mowomre BLACKBURN AIRCRAFT CORPORATION MARINE AIRCRAFT CORPORATION GROSSE ILE AIRPORT, INCORPORATED GLIDERS, INCORPORATED UNION TRUST BUILDING, DETROIT CHANIN BLOG., NEW YORK » ROOSEVELT BLOG.. LOS ANGELES

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122 POPULAR SCIENCE MONTHLY Aprit, 1930.

——_, the top are made from a 34 by 134 by 13 in. piece of stock, and the back member | D and the front E from a piece 34 by 24 in. and long enough to allow spare wood for finishing. True up all the edges and place the parts on the full size plan to obtain the proper angles. Fit each joint separately, allowing about % in. in length so that the frame can be trimmed to the exact size. On each joint attach small triangular blocks G so that they will act as bearings for the hand screw jaws Y. Fit 34-in. dowels in each joint and make a trial assembly of the entire frame. After a perfect fit is obtained, glue permanently with the aid of hand screws as illustrated. After the glue has hardened, smooth and sandpaper the frame and fit it to the He flew the first air mail from the United States to a foreign country With more than 5,000 flying hours to his credit, he has taught Aviation to many men now holding big positions as pilots and executives.

HAND SCREW. ——— 2%— LAF Y>

GLUING TOP Cc FRAME

, : SECOND GLUING group of noted flyers and Lieutenant Commander Iseman » FIRST GLUING ¢ ND now together with a The two gluing operations by which legs and ; . . Y technical experts, he has put into a great new operating Manual a complete course | sali ane commmliade: aw 40 ae aa tes for beginners in flying. It is so accurate, so thorough, so reliable, and yet so ney and graphically explained that not only do beginners advance themselves with far rege? : ’ greater rapidity through its use, but engineers, pilots, executives, and other leaders | aye _ with dowels as _ < a in aviation are using it and proclaiming it the best general reference guide-book andl arg aye iciage hte e* - NeXt, in the whole field of Aviation. make the two flaps K and hang each one with two hinges. © 4 Two trays are made as shown and The Aviation Manual fastened to the stand as at L, being held in place with glue and brads.

Edited by : ‘ Over600 pages, 150 The entire surface then should be sand- Commander Iseman has more than 5,000 flying hours to cluding diagrams, the wood is to be left in the natural color his credit. Additional contributors are Col. N. J. Boots, | ¢7@wings, and a simply applied finish consists of three General Supt., Roosevelt Field; Merwin M. Peake, Cur- Fy 0 Flex- or more thin coats of light orange shellac, tiss Flying Service; G. B. Speir, Curtiss engineer; J. D. H ne, Fe each rubbed with No. 4/0 sandpaper. Peace, Jr., Specialist in Instruments; Otto H. Lunde, od i — The last coat should be polished with wax. Fairchild engineer; Lieut. Assen Jordanoff, veteran pilot; — Strap racks can be fastened on cloth- Travis Hoke, authority on meteorology. ' covered pasteboard, which in turn is attached to the flaps so as not to interfere with closing them.—CHARLEs A. KING. A Complete Ground Course for Be- ginners in a Single Handy Volume “How can I get into aviation?"’ many men are asking. ‘‘And what must I know before I can take flying lessons?’’ This great new book is the answer to both questions. In a clear, thorough, and practical way it completely explains all of the things the ginner must beceme familiar with—it offers the background needed by the man who wants to fly—it presents the knowl- edge he must have of planes, motors, and instruments; of the theory and practice of flight; of license regulations, air traffic rules, and the requirements of commercial aviation. 2 7 aa Graded Chapters on Airplane

Increasing the Life of Form Cutting Tools Y MAKING form tool holders a little higher and providing them with three binding screws instead of two, it is possi- ble to obtain more use from any given length of tool stock. The extra screw allows the bit to be moved up farther and thus makes it possible to use the Construction, Equipment, and Control

Opportunities in Aviation Power Plants The Business of Flying The Manufacture of Engines tools long after they would have become cense Requirements nstruments alifiestions for Flying Elementary Airplane Design, too short for bags? ana type of form tool raining to Be an Aviator aterials an r Properties octane Your Background of Knowledge Wings and ‘‘Props” holder.—H. L. HEELER. Aviation Schools and Flying Clubs Wind and Weather Bee to Get the Most Out of a Fly- Bow . Pilot Inspects His Plane HEIGHT OF ng Course rning to Fly a Your First Outfit Advanced Flying Che og 2 FORM TOOL HOLDER : Standard Airplanes, Seaplanes, and Laying an Air Course Amphibians Air Traffic The Construction of Planes The Laws of Aviation FREE EXAMINATION

2 gar So cae tig Desk $0 peu oe: on ess ee sse2eaaaeee ays’ examination. ithin that period you FR « * may vs s and one eae Our ~ : , EE Examination Form usual manufacturing facilities together P cy oe with the large edition it is possible to make 381 F _ ee gg je | Co., P.S. 4-30 HEIGHT - INCREASE of a book in such great demand, enable us our ve., INew tor OF BLOCK to place the low price cf $5.00 on this book. Please send me a copy of The Aviation Manual. | NO MONEY IS REQUIRED until you Within 10 days of receipt I will either return the book | have examined the book itself. Send the or remit $5.00. coupon. g ee SN 8 bs skin 0543 said neacmenseen deat hea bhemidaeade Popular Science Publishing Oo. ° ° Cc , Address Cece reece eres ecerececeseseseseeeseseseseseseeese The increased height of the block will pro- 381 Fourth Ave., New York SESAME LOST OS vide space for the additional tightening screw.

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ia 1930. by 13 smber | y2% wood e the n the itely, that exact gular rings .g-in. trial ter a ently ated. 100th o the ittle hree OSsi- iven ‘rew ther the ome tool i AprIL, 1930 Casting Concrete Stepping Stones in the Ground Qiare stone garden walks of the kK flagstone variety can be easily and quickly constructed by casting concrete to the various shapes desired right in place instead of molding the blocks or using the natural stones and fitting them together in the proper pattern. First, lay out the path with stakes and cord to the width and general contour The wooden strips can be lifted out ten minutes after the concrete mixture has been poured. desired. Dig the path out to a depth of about 3 or 4 in., being sure that the con- tour follows the cord plan. Set wooden strips edge up along the boundaries of the path and then lay out the forms that the molded stones are to occupy. In this way a good idea of the arrangement can be obtained. In mixing the concrete, use one part of cement and between four and five parts of coarse sand. Mix this dry and then add sufficient water so that the mix is just wet enough to pour easily and not so soft as to be sloppy. Pour the cement into the box forms, being careful to see that all of the corners are filled and that the concrete is even with the ground. After smoothing out the surface of the concrete, allow it to stand for about ten minutes and then carefully remove the wood strips. The cement will be firm enough to hold its shape and all that is necessary is to allow the walk from three to four days to harden. When the concrete has hardened sufficiently to allow it to be walked upon, ill the cracks between the stones with soil. If grass seed is sown on this earth, it will soon sprout and add to the attrac- tiveness of the stepping stones. By pouring the concrete so that it is . = = Any flagstone design can be made by outlining the desired forms with short strips of wood. POPULAR SCIENCE MONTHLY Just 15 Minutes a Day What it will mean to you is told in the FREE BOOKLET below ERE are two men of equal position and business in- come. Which of them represents you? They read about the same number of hours each week. But one has no plan for his reading; at the end of the year he has little or nothing to show. The other talks like a man who has traveled widely, though he has never been outside of the United States. He knows something of science, though he had to stop school at fifteen. He is at home with history, and the best biog- raphies, and the really great dramas and essays. Older men like to talk to him because he has somehow gained the rare gift of thinking clearly and talk- ing interestingly. What’s the secret of his men- tal growth? How can a man in a few minutes of pleasant read- ing each day gain so much? Dr. Charles W. Eliot, from his lifetime of reading, study, and teaching, forty years of it as President of Harvard University, answered that question in a free booklet that you can have for the asking. “For me,” wrote one man who had sent in the coupon, ‘your little free book meant a big step forward, and it showed me, be- sides, the way to a vast new world of pleasure.” This free booklet describes the contents, plan and purpose of DR. ELIOT’S FIVE-FOOT SHELF OF BOOKS Every well-informed man and woman should at least know something about this famous library. The free booklet tells about it—how Dr. Eliot put into his Five-Foot Shelf ‘‘the essentials of a liberal education,” how he so arranged it that even “fifteen minutes a day”’ are enough, how in pleasant moments of spare time, by using the reading courses Dr. Eliot provided for you, you can get the knowledge of literature and life, the cul- ture, the broad viewpoint that every university strives to give. Every reader of this magazine is invited to have a copy of this entertaining book. It is free, will be sent by mail, and in- volves no obligation of any sort. Merely clip the coupon and mail it to-day. This Free Booklet gives Dr. Eliot’s own plan of reading P. F. COLLIER & SON DIST. CORP. 250 Park Avenur, New York City By mail, free, send me the book- let that tells all about the most famous library in the world, de- scribing Dr. Eliot's Five-Foot Shelf of Books (The Harvard Classics), and containing the plan of reading, I _ recommended by Dr. Eliot. Also, ! please advise how I may secure the books by ! small monthly payments. ! ’ (Mr. ? M: b { \ Name | Seer I ye Pepe rbepehd Battal dion I i 8063-HCC ] i ] ee ee ee eo

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124 POPULAR SCIENCE MONTHLY APRIL, 1930 “‘Here’s the Rule You Need” The FARRAND RAPID RULE The Original Rigid-Flexible Concave Rule On the job, in the office, or in the home workshop, you will find the Farrand rule one of the most practical inven- tions in years. It modernizes old methods of measuring, since it combines the better aes Sone Ame nmne — features of the wooden rule and steel tape without their many limitations. Will measure with equal ease straight or curved surfaces, and around bends. Six and eight foot steel rules coiled in a vest pocket sized holder. Instantly available for service by slight pressure on brakes. Ask your dealer to demonstrate, or write to factory for six-inch sample of rule strip. Manufactured by HIRAM A. FARRAND, Inc. Berlin, N. H. The finished walk should be allowed to harden for at least four or even five days before it is used. | flush with the surface of the surrounding '-soil, the walk will not serve as an obstacle for a lawn mower and thus will allow the easy cutting of the grass between and around the stones.—H. B. Checking Small Holes with Vernier Calipers B* THE addition of small pins fitted on the jaws of a pair of vernier calipers, it is possible to measure accurately the distance between small holes drilled in thin plate stock. The pins are fitted in plugs which, in turn, fit the ‘ends of the caliper jaws and are held in place with small thumbscrews.—JOSEFH C. FISHER. 7 / ff Pi? ee // 8 4 f/ ; yh if WORK \ J Nees 7 V5, 54,5 Le GIP RY | The inside edges of the pins should be on a line with the inside edges of the jaws. OvuTSIDE painting should be done under favorable weather conditions. Never paint during or following a rain, heavy dew, or frost; in damp, foggy atmosphere; or when rain is threatening. Neither at- tempt it in freezing weather. If the sur- face is cold, the paint may crawl and sag. If the paint freezes before drying, the appearance of the job is ruined, and it is not very satisfactory even if painted over. Spring is more popular than any other time of year for painting. However, spring painting should never be done (except in the warmer climates) until there has been sufficient dry, warm weather to overcome the effects of winter rain, ice, and snow. Fall is always a good time to paint, as generally there are few rains and the lumber is in good condition. Orhis seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. Ceiling eracks You can easily make cracked walls and ceilings good as new with Rutland Patching Plaster—the quick, money-saving mender. Just mix with a little water, then fill crack or hole. If you want a perfect, lasting job, be sure to ask for Rutland Patching Plaster— made by the secret Rutland formula that insures ahsolute whiteness and perma- nence. At paint, wall-paperand hardware stores. Rutland Fire Clay Co., Rutland, Vermont. RUTLAND PATCHING ad Oe Catch More Fish In 1930 Hildebrandt’s Hints tells you how —shows you the old favorites—fish- catchers for thirty years—and many new items. Hildebrandt Spinners spin so easy—good for all game and pan fish. Send for your HINTS—IT’S FREE. John J. Hildebrandt Co., 1154 HighSt., Logansport, Ind. Tool Chests for Machinists and Toolmakers Highest quality, best ma- Catalog free. H. GERSTNER & SONS 576 Columbia St. Dayton, Ohio The Midget “‘Five-in-One” Slide Rule mix \e snd Tangents. Wade of algminam with \e um scales on white celluloid. 4in Ae. and adop’ : Fath instractions: $190 sesed. Gate eo SB art" (Patented 1 Stuart.Florida A definite program for getting ahead financially will be found on page four of this issue.

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1930 E * % ee Aprit, 1930 POPULAR SCIENCE MONTHLY Easily Constructed Rack Holds Fishing Rods Fahd small amount of set that the tip of a fishing rod may have sustained in the course of a day’s fishing can be re- moved if the rod is hung in the handy clothespin rack shown below. The heads of a number of clothespins are shaved off and the pins inserted in holes bored in a strip of wood 1 in. thick and 2'%% in. wide. This strip is attached to the wall by means of brackets. The rack is especially useful in the case of those fishermen who use bamboo rods and wish to keep them in perfect condition and free from any set. The rack can also be used for hanging lures and plugs.—RoBERT PAGE LINCOLN. The rack can be at- P tached either to the hes wall or to the ceiling. i FISHING one CLOTHESPIN (HEAD REMOVED) | Support for Power Hack Saw Stock SUBSTANTIAL and handy support for rod stock which is being cut in a power hack saw can be made from short ends of scrap iron. The parts assembled consist of two pieces of 2-in. angle iron, 8 in. long and bolted to a piece of 10-in. channel iron, which are supported from the floor by two legs which can be made from any suitable size of flat stock iron bent to the shape indicated. A cast-iron or steel roll is placed be- tween the angle iron supports to serve as a rest for the free end of the stock being cut. The height of the support should be made the same as the machine with which it is to be used.—H. L. WHEELER. Meat HEIGHT SM j FIT SAW FRAME - A ¥-in. steel roller serves as a rest for the end ON ON 4 oR of the stock being cut on the power hack saw. PLASTIC WOOD Reg. U. S. Pat. Off. When the car begins to squeak, when joints loosen, leaks open up at the windows, doors or top—then is the time for Plastic Wood. It is used for intricate work by the repair shop. It can be used for simpler jobs by every owner. Here are some practical uses. Dented Fenders Scrape away all paint, rust and dirt. Build up with Plastic Wood slightly above the de- sired surface. When hard, sandpaper down to shape, and apply paint or lacquer. Worn Out Door Bumpers Push out the bumper to the required position, and build up underneath with Plastic Wood. Close door gently against bumper and allow the Plastic Wood to set. When hard, scrape and sandpaper the edges smooth. Enlarged Screw Holes When hardware becomes loose, or must be re-set, and for en- larged screw holes under floor boards, fill the old holes with Plastic Wood and allow to harden. When screws are re- placed they will have solid wood into which to bite. Plastic Wood is the product of a thousand uses around the home and for the car. It adheres lastingly to wood, metal or other mate- rial when the surface is dry and clean. When hard it can be worked with tools like any natural wood. It will not disintegrate, crack or splinter, is waterproof and greaseproof, and takes paint, varnish or lacquer perfectly. PLASTIC WOOD Handles like Putty Hardens into Wood At Hardware and Paint Stores Tube, 25 cents Y4, lb. can, 35 cents 1 lb. can, $1.00 Solvent, for thinning Plastic Wood, 25 cents A folder describing “Plastic Wood for Auto- mobile Body Repairs” sent free on request. ADDISON-LESLIE CO. 326 Bolivar Street Canton, Mass.

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ne Rt ect

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| 126 Send for this Sample Package _ ae == > = a a ae | F The ; . ie : Strongest | Adhesive ert . ee ae. i and Known!

a Casco will glue practically everything —wood to ave | metal, glass, card- board, leather or paper—and glue it permanently. It is an all-glue dry powder which you simply stir as required in cold water and apply. No Waste—No Heating— No Odor You mix it cold and use it cold. One pound of dry powder makes 114 quarts of high-powered liquid glue—and it spreads further. It is unparalleled in strength—a Casco-glued joint is stronger than the wood itself and will stand up, inside or outside, in any climate because CASCO GLUE IS WATERPROOF Casco has been used for many years by leading aeroplane and woodworking in- dustries——but is now available to every- body in convenient 14 and 1 pound packages. Try it on any difficult gluing job on which other adhesives have failed. Fill out completely the coupon below— one test will convince you that Casco is the most practical, durable, convenient and inexpensive glue you have ever used.

The Casein Manufacturing Company of America, Inc. 15 Park Row, New York Enclosed find 10¢ (stamps only) to cover postage and handling cost for which send me your trial package of Casco Waterproof Glue. clude)

POPULAR SCIENCE MONTHLY

Installing Closet Conveniences N THE hardware store, the department store, the home furnishing store, and ‘ even in the “five and ten” may be found | various inexpensive closet fixtures which add much to the capacity and con- venience of any closet. To install them requires nothing more than the ability | to use a screw driver, for usually all neces-

SHELF mses | ue | | | NS) } yg i ng / $9.L, | I Rr Re a — CLOSET pai’ H :

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CLIPS ; |

By utilizing the space on the back of the door the capacity of any closet can be increased. sary screws and fittings come with them. The garment fixture A may be pur- chased in lengths ranging from 12 to 60 in. by increments of 2 in. The shoe racks | B and C come in lengths to suit almost any space on a door, a wall, or a base- board. The rack D has obvious advan- tages, while the rod E is a hanging place for neckwear, belts, canes, and umbrellas. The adjustable closet bar F may be purchased in three sizes, 18, 30, and 48 in., one of which will suit any space between 18 and 78 in. The bracket rod G is made in 10- and 20-in. lengths and will support a surprising amount of clothing in a small space. The hanger H for trousers is more substantially made than many others of the same type; it may be used for hang-

TELESCOPING ROD-F JS cums = TWO LARGE FACTORIES rH ws hee Th

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|— Se =~ cg fri i ? Apri, 1930 Ses skirts as well. The hanger J will ac- commodate four pairs of trousers in a re- stricted space. Coat hangers of many kinds can be bought. The one shown at K is of some- what unusual design and will preserve the shape of the garment, besides supplying a convenient rack for an additional pair of trousers. After fixtures of these types are added, the walls of the closet in many cases will carry nearly as many clothes hooks as be- fore, so that the capacity is greatly in- creased and, at the same time, a more orderly and convenient arrangement is insured.—DAVID WEBSTER. Steel Square Simplifies Structural Layouts A CONVENIENT square for use in laying out either timbers or struc- tural steel can be made as illustrated by cutting a right-angle triangle from light- weight sheet metal. The triangle is extended 1 in. below the base line for at- taching the wooden guides, which are The square is made from lightweight sheet metal. COPPER RIVETS = SSS fastened in place with four soft copper rivets. The completed teol can be used for the same purposes as the ordinary try-square. In addition it gives a 45° cut without | making any adjustments or moving the | square, and the graduations allow an | angular cut of any desired degree to be | marked without stopping to adjust screws | or clamps.—C. B. DEAN. Block Puzzling—The Latest Craze Block puzzling, which is fast becom- ing popular with puzzle enthusiasts, is not new to the readers of POPULAR SCIENCE MONTHLY. Puzzles of this kind have been described in this magazine. many times in the past, and six especially ingenious puzzles of this type are included in our Blueprint No. 65 (see page 111). The solutions to the last two puzzles published (P.S.M., Mar. ’30, p. 133) are given below. POPULAR SCIENCE MONTHLY TO RIDE AWAY! PRING is just around the corner. Budding branches will soon be waving to you—beckoning you out to the Open Road.’ Ride away with the “early birds” this Spring. Get your Harley-Davidson now, so you both will be well acquainted and rarin’ to go when the first whiff of Spring comes in from the country. Drop in on your nearest Harley-David- son Dealer—look over the 1930 models with their scores of improvements—try out the wonderful “45° Twin shown here—and ask the dealer about his Pay- As’You-Ride Plan that makes motorcy- cle buying so easy. Mail the Coupon for literature showing full line—the Single, Twins, and Sidecars. »* HARLEY-DAVIDSON Solutions to two puzzles by E. B. Roberts. The pieces may be cut from wood or cardboard. LHe ais t 3 a yy —— —~ C ‘@) ) P ‘e) N 27 10 8 15 Interested in your HARLEY-DAVIDSON MOTOR CO., Dept. P. S., Milwaukee, Wis. ‘ als JAC Is motorcycles. Name Be 6} " 7 AN® \& Pisa Send MilDirliis, 1 cacarcnceoniesienniesnrrceempmemaieninamammmeeatiaaianaamiaimamtiaiiiieaiaaiaiaditinaai literature. My age is [] 16-19 years, [) 20-30 years, (] 31 years and up, [) Under 16 years. Check your age group. Vv a ES Sr SEDO Be ee er

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POPULAR SCIENCE MONTHLY Liners, freighters, yachts—all of them have to undergo b seasonal overhaul- | ing. They are like 4 new when they come out — sides shine with new paint — inside and out they are sound and ready to take j on another season | on the high seas. ' In this overhauling work, there are a mul- titude of uses for screws. Experienced shipbuild- [ : = lm ll } ers select American Screws for these jobs because they can trust them. They know that the strong bodies of American Screws will stand up under auto- matic driving; that they will hold fast in spite of unusual wear. =) ) 4: ) = \e ) ) ) J) Specify American Screws Send for our chart showing types and sizes of American Screws. a 0 A Un Rte OE ae | on na : . : ye i ¥ ey —- Ad of 4 WOOD MACHINE STOVE TIRE { SCREWS SCREWS BOLTS BOLTS AMERICAN SCREW €O PROVIDENCE,R.1.,U.S.A. WESTERN DEPOT,225 WEST RANDOLDN ST_CHICAGO.ILL, Put ft Together With Screws ec he An Escape Trick and Envelope Mystery By GEORGE S. GREENE oad Escape from these witch stocks seems an al- most impossible feat to those not in the know. sible is one of the requisites of all magicians, amateur and profes- sional. For instance, escape from the “witch stocks” illustrated would be quite a feat—unless you knew just how the trick is done. The effectiveness of the trick is only surpassed by the ease with which the stocks can be constructed and the sim- plicity of the trick itself. The stocks are made of 1 by 2% by 11 in. boards. The oval wrist holes are 214 in. wide, 2 in. high, and are 314 in. apart. The boards are fastened at one end with a steel hinge, at the other with a brass hasp and lock. In preparing the hinge, remove the pin and saw a %-in. piece from the end. This piece is soldered back in the hinge, projecting slightly, and the remainder of the pin is replaced from the other side. Bend the pin very slightly so that it re- quires a pull of the finger nail to dislodge it. A push on the bolt-end soldered in the hinge will convince anyone that all is secure and that the bolt could not pos- sibly be removed without a hammer and [=e what seems to be the impos- oy By twisting the left hand, to position shown, the pin can be withdrawn from the fake hinge. . © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. APRIL, 1930 What is Starting? Why should all the great industries now be offer. ing new knowledge, new hints, new help, new facts, —to workers in otheri ndustries? Not just to specialists and executives, but to workers in all ranks,—men who think as they work, and whose thinking has produced, in the past, g9 many advantages great and small, for their employ. ers, and for consumers. What’s this About Fact-Sheets of Industry? What is in it for the employes and executives who get them? What’sin it for the companies they work for? What isin it for ME? What are these big national industries getting out of it? What has it got to do with faster improve ments in business, in industry, and in the circuit of general prosperity? Or with the new direction that industrial thought is taking? See for Yourself. Send Name. It costs you nothing. If you work on any product that is used by concerns that serve the public, o¢ used in businesses or homes; for utility, beauty o¢ luxury, the first of the Fact-Sheets of Industry wil] start you thinking; perhaps amaze you. There is no obligation. Just state name, address, kind of work you do, company’s name and products, and if request is for self. Save this; don’t trust to find it again. Edition now in preparation is limited, so write at once. Address: Fact-Sheets of Industry, Dept.0o-3 N. V. F. Co., Wilmington, Del. ¢ 2 ¢ Offer is by NATIONAL VULCANIZED FIBRE COMPANY; its Divisions and Associated Indus tries. Special working methods; special Phenolites; “righter” Bakelites; parts, materials and ways; Material Handling equipment; etc.; besides Vulcanized Fibre. Serving Al Vv - America’s industries, from Smallest to Greatest. i“ ” * Reception AMPERITE auto tube voltage. Improvestone, sensitivity, volume. For every tube. $1.10 with mounting (in U.S.A.). At all dealers. 661 BROADWAY, NEW YORK ° FREE—"“Am Tube Chart.” Write Dept, PS4 E: “Vs PAT OTe Rheostat Build a Ship Model at Home for Pastime and Pleasure It is a wonderful fascination and a beautiful deco- ration for your mantel, radio cabinet or it may be used in any part of the home. Santa Maria, size, 25 inches high, + 10 inches wide, 27 inches long $4.98 La Pinta, size, 26 inches high, 11 inches wide, 27 inches long. . $4.98 Mayflower, size, 26 inches high \ 10 inches wide, 30 inches long $4. y Constitution, size, 25 inches high 8 inches wide, 29 inches long. $6. Flying Cloud, size, 27 inches h 9 inches wide, 36 inches long. $6.98 These prices are f.o0.b. Philadelphia, plus a few cents postage. These models are sold in knock down form. All Parts are cut to fit and ready to assemble. They will be sent anywhere in United States C. O. D. Money order or check must accompany all foreign orders. Wrtte for free illustrated catalog. MINIATURE SHIP MODELS, INC. Dept. NA-4 Sellersville, Pennsytvania WADE BENCH LATH Cap. 4 in. dia. x 12 length. Sliderest has tra No. 2 Lathe, back- headstock --------- 68. Complet ey ers equally low prices. Catalog sent free. THE GEROLD COMPANY | Dept. P. S. 15, 120 Liberty Street, New York GEARS In stock—immediate delivery Gears, speed reducers, sprockets, thrust bearings, flexible couplings, pulleys, ete. A complete line is carried in our Chi stock. Can also quote on special gears of any kind. Send us your blue-prints an Write for Catalog No. 214. Chicago Gear Works, 769-773 W. Jackson Blvd. , Chicago, il.

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De offer. Ww facts, but to 'Y work, Past, so employ. ? ves who ©y work ting out nprove- rcuit of on that me. product iblic, or auty of try will address, roducts, trust to limited, dustry, FIBRE Indus nolites; ways; /F

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APRIL, 1930

POPULAR SCIENCE MONTHLY

freedom of the hands for swinging it. A small quantity of burnt umber dis- solved in alcohol and dabbed on the wood with a cloth adds to the antique appearance, as does the rusting of the hardware by moistening it with salt | water. Care should be used to polish and oil the inside of the hinge and the bolt after this treatment. Often an antique padlock and key can be purchased at a secondhand store, and

STOCK HINGE TWO PIECES 2% a 1

BOLT END CUT OFF { SOLDERED Of © HINGE offo

Drawings of the assembled witch stocks and diagram showing construction of the hinge if they are not sufficiently worn with age they can be made so artificially. The use of a marked piece of adhesive tape over the keyhole after the stocks have been locked on dispels any thought that 2 duplicate key is used. When the stocks are locked on the performer, using a borrowed padlock if desired, he has only to go into retirement behind a curtain for a moment to remove them. He twists his left arm around and removes the pin with his finger nail to make the escape (see illustration bottom of page 128). The bolt is replaced before allowing the stocks to be examined. Close inspection will not reveal the secret, and considerable fun can be had by offering to allow a spectator to try to make the escape. Much of the success of the trick, of course, depends on the manner of presen- tation. A well planned “patter” (talk) has been prepared and can be obtained by sending a stamped and self-addressed envelope to POPULAR SCIENCE MONTHLY, 381 Fourth Avenue, New York, with a request for Home Workshop Bulletin No. 4. In performing the bewitched ribbon trick, you show an empty envelope, a yard of ribbon, and a playing card. A slit is made through the envelope with a knife and the ribbon is threaded through it so that half of its length hangs down on either side. The playing card is marked with a number or name suggested by the

— The arrangement of the envelope, showing the duplicate card, tracing paper, and false front.

8” Circular $6”" Lathe, Sander, 6’ nder, 4"

Wand 2c" Palle, an ‘ulleys. Cast Iron Sub Base. 10 fe. Cable with sep- arable Piug. Planer and Saw may be pur- chased sepg arately

_ Jig Saw Attach- ’ ment. for. the 14in. Workace Band Saw, fast, accurate, economical. .......' Pie

Workace Electric Sha aewraee ‘adie ....995

4in. Planer.......

blectric

ERE’S A HOBBY that gives you relaxation from everyday cares bringing pleasure and profit. Thousands of men have adopted the Workace hobby. Make hundreds of things with the Work- ace Electric Woodworker. Under the magic of the whirring saw, planer, lathe, sander, drill, grinder and buff- ing wheel (all are included in the Workace Woodworker) raw lumber is easily converted into furniture, household necessities and countless other articles. Work out your own ideas with your own complete elec- tric workshop. There’s no better gift for the grow- ing boy than Workace. It provides a wholesome man-building outlet for his energy and enthusiasm. Man or boy will appreciate the Workace. $9.00 down will bring it. To operate ww plug into 11 West 42nd Street, New York City 268 Market Street, San Francisco

Consult telephone directory for branch addresses in other cities se S D. W. Workace Portable $95 te I J. ALLACE & ANY, . t COMP. Wilcox St. at California Ave., Chicago, Ill. ae a | Please send me full information about the Workace Elec- ae | <= Woodworker and also the Workace Machines checked iow. Workace Workace Jig Saw Band Saw Workace Workace Workace Shaper Planer Radial Saw EEE EEO d Se e ttf T, Gad the electric light socket. Send the coupon now for details. J.D.WALLACE & COMPANY Wilcox Street at California Ave., Chicago

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

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1 MRE se wt ee en ore wre Onn he aa “ 130 POPULAR SCIENCE MONTHLY Plans - - Diagrams - - Directions for Wonderful New Things to Make HOME WORK- SHOP in your The most modern, most complete, and in every way the most practical Manual now available for the man who likes to make things with tools, Brand New Just Published The scope of The Home Workshop Manual is really amazing. It is hard to believe that such a great — things to make can be covered in such complete de- tail until you actuall see the book and loo through its sixteen big sections. 735 Illustrations Once you have seen these wonderful photos anddiagrams, andhave worked out for yourself some of these plans, you will readily admit that it is the most helpful tool in your whole kit and that it will be worth many, many times its cost to you. THE HOME WORKSHOP MANUAL It gives you clear, complete, and simple directions for doing expertly all those jobs of craftsmanship you've often thought of doing, and suggests scores of others you can easily do with the proper directions. Put this handbook in your tool chest for quick reference—follow its plans and directions every time you have a job to do with tools. Whether you are interested in woodworking, in | metal work, in ship and airplane model making, in radio building and electrical work, in sporting equipment, in painting and decorating—or in all of them— you will find an expert of high standing in each field ready to guide you with instructions you can readily understand. The Sixteen Sections of The Manual Are Graphically Illustrated 9. Model Making 10. Radio and Electrical Projects 11. Improvements for House and 1. Building Fine Furniture by Hand 2. Furniture of Modern Design 3. How te Use Small Woodworking achine Garden 4. Repairing Old Furniture 12. Boats and Sports e 5. Toys to Delight the Children 13. Painting and Decorating 6. Novelti amental and A- 14. Woodworking Tools 15. Retoment to Make for Your ome Shop 16. Better Home Workshop Methods musing 7. Woodturning Simplified 8. Decorative Metal Work We Will Deliver It Immediately --for FREE Examination While it is the finest work of its kind ever ==="ORDER ON THIS COUPON™*"""™ roduced by any publisher, its price is only Popular Science Publishing Co Apr. 30 .00. No such investment that you have ever I 381 Fourth Avenue, New York, N. Y. : made will bring you the pleasure, and satis- Please send mea copy of THE HOME WORKSHOP faction and profit that you will secure through l MANUAL for free examination. Within ten days your —— and use q this manual. And 4 of rooees I Sig A; iy) she vereme, Be dé we we ou need not pay a penny for it until after you owe no’ : From : n ave gone Ghoneuakie through its profusely | ten days which pays In full for the Manual. illustrated pages. You need send no money 1 NOW—the manual will come for FREE BRED 6.665600 esc eceFe ccc cvesseesasesetasesses Examination. And if you decide that you do not need it, simply return it and you. owe J IES «0, tetsu dh ae Sardi Sih Goldin ed Ree a Sioa ee nothing. Otherwise remit $5.00 and retain the manual. I iO i ot SE Ss ok ae ee APRIL, 1930 When the envelope is opened the ribbon is found to be threaded through the playing card. audience and then sealed in the envelope. When the envelope is again opened and the marked card is withdrawn the ribbon will be found to be threaded through it as shown in the illustration above. The ease of the trick lies in the simple preparations. The envelope has an inner partition consisting of the front and flap of another envelope, with the two flaps sealed together. Inside of this secret partition is a sheet of red carbon paper and a duplicate play- ing card, arranged so that writing on the envelope face will place an impression on the duplicate card. The pencil used to mark the original card, which is rested over the envelope during the marking, is a red one in order to exactly match the carbon impression. Red is chosen because it is one of the easiest colors to match. It will of course be understood that when the ribbon is first threaded through the envelope, it also passes through the duplicate card. On removing the latter at the conclusion, the carbon paper is retained in the envelope by having been previously glued at the corners. Much of the success of the trick de- pends on the careful arrangement of the envelope, fake back, duplicate card, and red carbon paper and on the ease with which the duplicate card is removed. = c y em 3 The ribbon is threaded through the envelope and then the marked playing card is inserted.

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1 is ird. lope. and »bon it as nple nner flap laps heet lay- the 10n ‘inal lope rder ion. the that ugh the tter r is een the and vith APRIL, | of an old steel oil barrel. 1930 Cheap Self-Feeder Reduces Cost of Keeping Pigs Wi the expenditure of but a little time and money, it is possible to supply a farm with a waste-preventing self-feeder for pigs as shown below. The practical value of this design can be gaged by the fact that Prof. B. V. McCaul, of the North Dakota Agricultural College, has built several of them for use on his own farm. The main part, or hopper, of the feeder is made by removing the top and bottom This can be ' accomplished by cutting it with an or- dinary cold chisel. The framework for the base can be either six or eight sided. Construct the frame from 2 by 4 in. stock, making it large enough to allow a minimum space of at least 8 in. from the outside of the bar- rel to the inside of the frame. A floor of FEED HOLDER MADE FROM AN OLD STEEL BARREL , . = OPENING An old steel oil barrel with its top and bottom removed serves as the hopper for the feed. 1-in. boards is nailed to the underside of this frame. The inside cone is made of lightweight sheet iron and should be about the same in diameter as the inside of the barrel and about 8 in. in height. The adjustable legs are made from pieces of 1 by 6 in. strap iron. Bend each piece to a right angle at about 2 in. from one end and supply the opposite end with a slot. Bolt the shorter end to the base, and fasten the slotted end to the barrel with wing nuts, which allow the flow of the feed to be adjusted easily. Careful ad- justment will eliminate any waste of feed. In order to keep the feed always free and unclogged, three or four chains (made by wiring several lengths of old tire chain together) should be attached to the inside of the barrel near the top and allowed to hang down and come out through the feeder opening. The lower end of each chain should be fastened with staples to the base out near the inner edge of the frame. The pigs will move the chains as they eat and thus keep the feed loose and work- ing towards the opening. The hopper should be provided with a tight-fitting cover to keep out rain and moisture. This can be made of either wood or thin sheet metal. If kept in good condition, a feeder such as this should accommodate about ten or eleven 250-Ib. pigs—Cap E. MILier. POPULAR SCIENCE MONTHLY 131 Yes, and it’s FIXED for LIFE! Wuar a help to the man-about- the-house! Mix up a little Savogran Crack Filler in a dish, take your putty knife, and in no time at all you’ vegot those annoy- ing little “fix-it” and repair jobs out of the way for good. Savogran Crack Filler won’tshrink! Repairs are permanent. Easy to work, taking paint perfectly, low in cost (note price), Savogran Crack Filler is the ideal filler for pluggingcracksand holes, building up surfaces, making models, inlay work (can be colored when mixed), etc. Send for demonstration can —see for yourself. Use coupon. Savogran Crack Filler is a product of the Savogran Company, makers of the famous Painters’ Savogran used by painters and householders for over thirty-five years. Painters’ Savogran renews hard paint- brushes, cleans dirt and grease like magic, removes paint and varnish, strips off ground-in dirt without scrubbing. It will save you time, money, and hard work. SAVOGRAN CRACK FILLER PATENT APPLIED FOR WON'T SHRINK! Big One-Pound Can Painters, Industrials, and other large users—note these prices! One Ib., 30c.; 5-Ib. can, $1.25; 35-Ib. all- metal pail, $7.70. No hardening in can—no waste. ONLY 30 cents Savogran Co., India Wharf, Boston, Mass., Dept. $4 I want to give Savogran Crack Filler a work-out. I enclose 10 cents. Send me a \-lb. can by return mail. 1 LES SU NO eT ee ae THIS Kyra tier p- r 1194 ‘Big Special Discount Eee’ 8 a modern 7-room home that Ag’ can build y ourself and sav®money. We ship you the a eut-to-fit, freight to your station. Our simple plans rm xem of cutting make it easy for anyone to a Sterling Some No sk: labor necessary. Our customers claim average sivings of 47 Y over local builders’ prices. Rock-Bottom Prices! Gee kenge vata of mais enatien we te ansts tock: prices and sell 3410 S. Wenona Ave. aa international Mill & Timber Co. Bay City, Mich. Rather Different! This expansive Bit is as strong and dependable as an auger bit. The cutter is clam | in a solid st one-piece head and can’t loosen or ‘‘creep.’’ It op- erates on a worm adjustment; one complete turn of adjustment screw changes the diameter of hole %”*. Look for the full name RUSSELL JENNINGS, on the shank. The RUSSELL JENNINGS MFG. Co., Chester, Cons. © 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 DRILL « is only 92 OVERALL 3000 R.P.M. packed in only 9% inches, power-a-plenty contained in only about three pounds—no wonder the new 3” Millers Falls Electric Drill marks a new step forward in the development of electric tools. You can handle this new power tool as easily as you would a rat tail file—reach in and out of inac- cessible spots—ten inches of space is all you need. Carefully built, strongly made, the Millers Falls *4”" Drill is only $36.00. Price includes auxiliary handle. The housing is made of ‘‘Raco- lite,”? a non-conductor of heat and electricity. Send the coupon below for a full description of this new Millers Falls Tool. MILLERS FALLS COMPANY, Millers Falls, Mass.; NEw YORK: 28 Warren Street; CHICAGO: 9 So. Clinton Street; Cable Address: MILLERFALL NEW YORK MILLERS FALLS ELECTRIC TOOLS Millers Falls cieiane Millers Falls, Mass. Send complete description of this new drill. Address__. a Name Aa 3 pound inches ‘HOME WORKSHOP CHEMISTRY Simple Formulas That Will Save Both Time and Money J‘OR cracks in floors and other wood- work that are too wide to be filled _ satisfactorily with common types of crack fillers, a hard, nonshrinking filler can be made as follows: Heat % Ib. of yellow ochre (a finely | powdered pigment obtainable at any large paint store) over a flame to drive off all moisture. Melt 1% lb. of rosin and add to it % lb. of thick turpentine, but remove the rosin from the fire before adding the turpentine. To this add the ochre and heat the mixture to keep it _ liquid until it has been thoroughly stirred. The mixture is heated and poured into the crack; any excess is removed after it hardens. Allow the filler to cool, and if it does not harden, add more of the rosin and yellow ochre. To use the mixture, heat it and pour it into the crack, which must, of course, be bone dry. Any surplus can be removed with a chisel after the filler hardens. Carpenter’s glue diluted with twice its usual amount of water forms an efficient hardener for use with plaster of Paris. The dry plaster is worked up with the diluted glue in the same proportions as when used with plain water. If potassium bichromate is added to the glue before it is mixed with the plaster, the resulting hardened mass will be more or less re- sistant to moisture. ey staining small pieces of wood where it is necessary only to cover up the natural color and where high-grade commercial wood stains are not essen- tial, it is possible to use chemicals. For example, by adding a teaspoonful of potassium ferrocyanide and another of ferric chloride to a glass of water, a blue stain can be obtained. If the color is not distinct enough, the addition of a tea- spoonful of oxalic acid will generally bring it out. A deep brownish-black or dark sepia stain can be made by adding six tea- spoonfuls of pyrogallic acid and two of cuptic chloride to a quart of denatured alcohol. To prepare a greenish-blue stain, add to a glass of water one or two teaspoon- fuls of oxalic acid and one teaspoonful of ferrocyanide, or one teaspoonful of fer- rous sulphate and one teaspoonful of potassium ferrocyanide.—H. Babe. © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. APRIL, 1930 J RoomAlADDIN Ay) Au Materials Readi-Cut Freight Paid Buy direct from the big Aladdin ) Bailie at a naratERe propel Sate amieal wumatet Save $200 to $1000 Aladdin Homesare cut- | eet at the Millon hugs instead vy on the job, y wren — where lab laborand lumber es 17 9 = thesditference and ge on oS ae tthe in Ne acceeh date aad What You “et ail materiale icccr one Pricesincludeall lumber readi- ome, miliwee pe a CT —_o doors, ~ rior woodwork, i hare ware, RF F- Catalog FREE Foetessty il uotsetess erflowing with pon Address mee office today or Garages °92 UP oor iciticiast All sizes~attractive de- signs. Prices are astoni: 7. iy ow. Bata'on ave ne yurself in Bay City, Mich., Portiana, Ore, a or two, . le a really enjoy the easy work! Wilmington, Build Model Airplanes the IDEAL way! Plans for Build this IDEAL Model Airplanes “American Eagle,” the 25c each. new, low-wing Model. 26 FLOYD BENNETT in. wing span, weight 3% MONOPLANE oz. A marvelous flyer Fokker Monoplane with tremendous power, New York-Paris and very easy to build. ircise Bipia Construction Set, con- Curt ra totene taining everything, in- woes > cluding instructions, $2.50. Assembled Model, NC-4 Naval: tans $5.00. Bleriot or Nieuport Monoplanes Ask your Cecil Peoli Racer Order Direct 48-page Catalog of Model Airplanes; Parts Materials and Supplies for Builders: 5c. IDEAL AEROPLANE & SUPPLY CO., Inc. 28 West 19th Street, New York City Factory to Days Dealer, or on the Mead Bicycle you ama. select from Styles, colors and sizes. e ship on spreyels. © If pot £ eatished ia + C. thet. MenTs. $" oo on R. Bicycles: amps, heme veauloment ata ; half us- I ire Sip TN i cle Company’ write ys Meads Depth BW Chicago tf. tree 1 FOUR PRACTICAL EDUCATORS! The Real Estate Educator The New Revised Edition, contains Questions and Answers; Brokers’ License Law; Dictionary of Wo and Phrases in Real manne and Construction; How to Appraise Property; Law of Rtal Estate; How to Adver- tise Real Estate; Legal Forms; Commissions to Agents; “Don’ ts om Contracts, ete. 388 pages. Cloth. Post- paid $2.0) The Vest Pocket Cushing t out. An A. B. C. Guide to Parliamentary Law my on the highest authorities and adapted to general use—containing model speeches and toasts for all occa- sions. 128 pages, size 24x4% inches, leatherette. Price, $1.00. The Vest Pocket Book-keeper and Short Cuts in Figures A simple and concise method of Practical Bookkeeping with py] tions for the correct keeping of books of account. How to take off a od balance sheet and finally close and balance accounts. 160 pages, artist fenthetetee.....cccccsccccccccccocsccccccsese e, postpaid $1. 00 The Vest Pocket Lawyer This elegant —— just published contains the kind of information most people want. A manual of reference for the business man—the law stu- dent—the justice —} the peace—the notary public—the farmer—the clergy- man—the merchant—the fe hanlior—tien doctor. 360 aaa. cloth e, postpaid $1.50 381 Pouth Ave., . y.c. POPULAR SCIENCE MONTHLY

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Apri, 1930 Remodeling a Tool Grinder to Do Tap Fluting By O. S. MARSHALL EFINEMENTS in modern machine shop taps demand that the flutes be spaced and ground accurately. As yet no special machine is available to do this work, but with the application of a few simple attachments it is possible to con- vert a small tool and cutter grinder into Fig. 1. The grinder set-up and wheel-truing device used to flute center-supported taps. an accurate flute grinder and spacer for use on small taps. In Fig. 1 is shown the equipment needed in grinding center-supported taps. The regular top or auxiliary swivel plate of the cutter grinder table was dis- carded and in place the two members A and B were substituted. Part A occupies the swiveling point of the main table, while B rests on lugs screwed into the table top. These lugs insure the align- ment of parts A and B. Part B carries the tailstock center C, which supports a double-ended center D. One end of Disa female center, which can be used for sup- porting small pointed end taps. The wheel-truing device is secured underneath B with two screws, and is capable of being set at an angle. With the correct setting of the diamond, truing is simply a matter of bringing the work- table to a position where the diamond will touch the wheel and rotating the diamond holder. To make the wheel keep its proper form and also relative position for the tap-flute, a setting bar G is provided. Part G is adjustable with micrometer pre- cision by means of the knurled and graduated nuts H. Tap flutes are set in proper relation to Fig. 2. A chuck attachment makes it possible to grind the negative angle in gun-tap fluting. POPULAR SCIENCE MONTHLY Make Things Quickly and Easily with the NEW 1930 | Craftsmen, artisans, farmers, mechanics—all who use wood in their daily labors or spare- time hobbies—are delighted with the sturdy construction, splendid efficiency, and moderate cost of this Delta equipment. ‘hey appreciate keenly in the ‘‘Handi-Shop” such exclusive constructional features as the Patented Tilt- ing Tables, Automatically-Oiled Bronze Bear- ings, Heavy U-Shaped Lathe Bed, Circular Saw sing Lever to mention but a few. Send coupon for complete description of this re- markable workshop. You understand then why men who know ae “Delta.” New Woodworking Units The introduction of the Delta Jointer and Cir- cular Saw Units marks a new era in moderate- ly priced wood-working equipment. Now, for the first time, are available sturdy, practical machines in compact, convenient form at price levels astonishingly low. The individual units are built ruggedly to give years of heavy serv- ice. Both incorporate many special features of great value. The combination unit affords a compact, convenient arrangement which per- mits sawing and planing in one quick opera- tion. Either Jointer or Saw can be operated separately or both together. Welded steel stand of convenient height. All three units are furnished with or without motor, as desired. 10 DAY TRIAL EASY TERMS For complete details and full description of the new 1930 Delta line, send coupon for FREE illustrated literature. 133 Make the th'ngs you have always wanted to make, with this sturdy, full-sized equip- ment. Save money on repair work—earn money in spare time. It is so easy—so quick with the ‘‘Delta.’’ Complete Handi- shop includes all necessary equipment for Circular Sawing, Wood Turning, il Sawing, Sanding, Drilling, Grinding and Buffing. Full Instructions and complete set of working blue-prints furnished. Shows many items of interest to those who work with wood. You will learn, also, how you DELTA SPECIALTY COMPANY, Dept. B-430 can try any Delta equipment for 10 days under Division of ‘‘Delta Manufacturin Go." actual working conditions at our risk. Choice 1661-67 Holton St., Milwaukee, of three convenient payment plans. Mail Pt we send A FREE, jotted erature doom pas ” a’ wor coupon TODAY! Trial Offer and Easy Payment Plans, (Check spe- 10-Da cial information des: D | S . } C C Handi-Shop “ Unit elta Specialty CO. [Airmen ante arte I am interested Division of . I am interested ay and professional use DELTA MANUFACTURING CO. | Name... 0 Moulding | Cutter cularly for home use 1661-67 Holton St. Dept. B-430 Milwaukee, Wis. A definite program for getting ahead financially will be found on page four of this issue Squab Book FREE PR squabs selling by millions to rich trade. Raised in » 1 month. No mixing feed, no night labor, no young to attend. Sell for — chicken prices. Write at once for free 48-p. book telling how to and_ profit new fast sales soeaiees. L OUTH R eee B CO.,616 H St., Beeteose H Shlomo. Massachusetts lished 29 years. Founder of the squab industry. in the world pan oy and pigeon my ny bank. We ship stock everywhere on co. Build a CLOCK por ?ipx0 —for fn - 5. or on 4 - Profits. We furnish instructions, parts. Works $1.65 up; others with chimes, ali prices. @® This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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PIE a OEE A ny ‘EY per

2 oto a Oey Oe lp 13%

The Newest Thing in Body Repai re TRIMO Ferquson Patfern BUMPING TOOLS

Old style methods of repairing damaged bodies are completely pew. ed with the coming of T “IMO Ferguson Tools. Only 14 tools are needed to do every job on any make of car. The tools are finely finished rk, — ed steel, of unique de- riected by a master body bail er. The illustration shows one of the spoons reaching a difficult spot ays dented door. Mechanics everywhere are find- ing it easy to do better and quicker work with these tools. Write to us for complete cata- log and description, or send one dollar for the the TRIMO- FERGUSON Manual, a com- plete text book on y re- —s written by an expert. opy sent postpaid anywhere in the United States or Canada.

TRIMO FERGUSON PATTERN BUMPING TOOLS (Application for Patents Pending)

Made by TRIMONT MFG. CO. Roxbury, Mass. Makers of quality tools for over forty years

POPULAR SCIENCE MONTHLY

the diamond position by means of a simi- lar micrometer adjusting device H, which is attached beneath the tailstock C. A clapper-block arrangement permits the locating bar to be swung clear of the tap and thus allows grinding room. The headstock A carries the live center and a forked dog, which is held in place by J. A chuck-holding provision for the same machine is shown in Fig. 2. In this case the work is held by the shank only, thus | allowing gun tap fluting to be ground. The headstock member permits both horizontal and vertical settings of the work in relation to its path of travel | against the grinding wheel. The special radius-truing device J makes it possible to give the wheel the correct form. This fixture is secured to | the emery wheel at the back and is so | placed as to bring the center of the swing

Fig. 3. The chucking and spacing device dis- mantled to show construction of various parts. of the diamond approximately over the center of the emery wheel. As the wheel wears away, the radius member may be lowered by means of the screw support K. The diamond may be set by microm- eter adjustment with the knurled nuts bb. The yoke L is manipulated by hand with the handle M. The disk N strikes against pins and limits this motion. The flutes of the tap are placed in the proper relation to the grinding wheel by means of the locating bar O, which is shown in its vertical position clear of the grinding wheel. This bar is also ad- justable by means of micrometer nuts. Details of the swiveling head member are shown in Fig. 3. Part / is set on the swivel point of the table and has bolted to it part 2. The spindle 3 has a tapered hole to receive either the chuck or the center drive support. A disk 4, with the required number of index slots, is placed on the spindle as shown. The index slots are tapered in form, having one side parallel to the spindle axis to insure the correct angular position of the work. The flipper pin 6 can be seen in the housing 2. Indexing is accomplished with the swinging lever 6, which has a pawl 7 that engages with the ratchet of 8. When all members are assembled, the ring rides free on 8 and is kept in place by the shoulder. The slots in the shoulder serve for the application of a spanner wrench. Details of the truing device for center work are shown in Fig. 4. This is made dust proof by means of two felt collars, one being placed at A and the other around collar B, which is within C' when the fixture is assembled. The endwise adjustment of the dia- APRIL, 1930 WORLD'S PREMIER CUSTOM RADIO Deliberately Chosen by scores of engineers for their personal use. Simple to assemble the “Hi Q- 30”? yourself from com- plete factory units or ask us for name of nearest custom-builder. A.C.— D.C.—and Battery models $139.50 to $1175 complete, less tubes. HAMMARLUND-ROBERTS, Inc., New York 424-438 W. 33rd St.

Send 25c a oe stamps) to Dept. for 48-page iio. Q- ro Manual.

Finest Cabinets, $

Including Phono- graph Combinations %

® This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. DIAMONDS WAICHES BT a Bd Op 23 30) BS Wee SES SEND FOR bus a CATALOG ReireiUy.A 2000 Illustrations | a How to Order \” | State article de- employer— kind of work you do— how longi in — ; env EVERY. ‘: mn THING T IS ee anti

gold, 1-Jowel - 1 $1.50 Down. $1.50 a Month . A ality, <i, P [SEL I: Sh;

b} | No. Elgin “‘Le- ionaire.””

as “38:08 G6 | F, Fires". Pm amNG sedan 92500 yg tp Lo west Sow loFtis ete coe A definite program for getting ahead financially will be found on page four of this issue.

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» 1930 \ Inc., York

Apri, 1930 cat tacieaill by means of the threaded end of the main member C and the collar B. With the adjustment made, B is locked with the wedging member D and forces the two lugs E outward against the | internal threads of B. These lugs are carried in holes as at F. | Other details are shown as 1, 2, and 3 in Fig. 4. Part 1 is one of the several clapper- blocks used in the construction. These

Fig. 4. The wheel-truing attachment, one of the clapper blocks, the cutter, and the locating bar.

blocks have holes 34 in. in diameter and 1 in. long, which are supplied with }-in. keyways. The blocks must be made ac- curately and the keyways should be good fits. The cutter 2, which was made for doing the splining, is of special interest. Member $ is the locating bar O in Fig. 2. | It is cut as a micrometer screw and has a | keyway cut along its entire length to | supply a means of keeping it in position and free from the slightest circular movement. Tapered Keys Accurately Machined in the Miller __—— keys can be machined quickly and accurately in the milling machine if they are held at the proper angle in the miller vise by the use of small blocks. For purposes of illustration, let us say that the taper figures .075 in. in every 674 in. Our blocks then must have a differ- ence in height of .075 and must ke placed so that any two corresponding points on _ TO BE MILLED ih SSS LEVEL

MACHINE MAKING THE BLOCKS ee How the two blocks are used, and a quick method of shaping them in the milling machine.

I ~*~ the blocks are exactly 674 in. apart. If as in this case the blocks are cut 7 in. thick, the distance between the inside surfaces of the blocks will be exactly 6 in. The blocks can be quickly brought to shape in milling machine in the manner shown. Placed as indicated, the blocks will give the upper surface of the key stock a slope equal to the required taper, and all that is now necessary is to run the cutter across the surface.—W. S. GALLMAN.

POPULAR SCIENCE MONTHLY Only For Both Motor and =, Screw Cutting Precision LL New Model South Bend 9” x 3’ Junior Lathe for the Manufacturing Plant Tool Room General RepairShop MachineShop Service Station Electric Shop Engineering Shop and Laboratory Lathe shownis the South Bend Junior Bench Lathe equipped with horizontal Motor Drive. Takes power from any light socket. Price complete with Mo- tor,$254, or on Easy Payments of only

$17.78 a month. Price of Lathe with- out Motor but with Countershaft and Equipment $169, or $11.83 per month. Prices of Other Popular Sizes of Quick Change Gear Lathes with Equipment ting’, Went watts Mixereene 9x3’ 490 Ibs. $294 $398 li’xd’ 725 * = 359. 498 13’x5’ = 1110 * 443 602 15"x6’ 1550 “ 543 720 16’x8’ 2035 “ 638 817 Write for Free Catalog lk all ascites *172aMonth &

—from 9 inch to inch are shown our com No. SOLA. Weite ra copy.

CAST OFF IN THIS BOAT, AND UNROLL A WIDE, WHITE WAKE Here’s a stout boat—this “Old Town.” She rides the water like a sea-gull—cuts along like a shark. Never shivers or vibrates—she’s built extra-rigid. The heavy, non-leak canvas has no seams to open up, and therefore won’t ever need caulking. Ideal for heavy loads, but wonderfully light and well-balanced. Free catalog shows big, fast, sea- worthy, all-wood, outboard family boats ; canvas-covered, square-stern boats with sponsons; rowboats; dinghies; speedy step-planes; and all types of canoes. Write. Old Town Canoe Co., 1154 Main Street, Old Town, Maine. “Old Town Boats” NIGHTS UD RAD ¢

Even i you Ram by ~ 4 netect ee, you play a simple me on the v Xyiorim ba. F 7 bande aoe your Dea: —. show ou how. Soon you are amazing and relatives. oe begins—long, happ: y evenings of Joy; partion; postion: ae $5 te fe 0 aye h Smith, chee ‘Played 2) minutes at received $20.’” minu a! o ey Paar d LAF.) FIVE. DAY: s” FREE TRIAL—Our bi FREE bos BE book tells all about this fascinatin; trial offer—the easy payment, plan. Sond in the coupon today—the booklet without cost or obligation. “ MAIL COUPON TODAY! J. C. Deagan, Inc., Dept. 1654 1770 Berteau Ave., Chicage Send me, without ebligation, full details of Free Trial offer and easy-payment plan on the Deagan Xylorimba. Name

Address

oil can as by—they a collected and returned to the crankcase. It fits FORD “A” fei it on. rae on to 2 scienti y ign back if not satisfied. perfectly—just ot out of order. money

36-48 Flatbush Ave., Ext. KEEP OIL WHERE IT BELONGS --IN THE CRANKCASE! Without the Whirlo Cap you are opreving < oil all over the outside of the motor. Oil rots hose connections—ruins ignition ion cable—

° draws grit ae = into vital working Dar ts—makes the motor Oil Filling Pipe Cap _ 14 before Tiny particles of oll are constantly being "being oon out through t the breather pipe. They collect on Cap does not contain screens, packing, to form a dirty, greasy slime that is d har etal vo oe filtering material or moving parts. tor, starter motor and all =e pages of Ha Faition evqeem, Give Whirlo allows free escape of crank- your moter a chenee—- ere og ty slime ae Cap keeps oil where it Lo pe aaepoees. only case gases but no flying particles of $1. ves in price times yt connections alone. Send no money. We mail it 'C.0.D. 5. $1.00 plus few cents postage. CARHART PRODUCTS

N. ¥.

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

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136 POPULAR SCIENCE MONTHLY Molding a Concrete Roller for Lawns By P. P. B. BROOKS Fig. 1. The completed 18 in. diameter concrete garden roller weighs approximately 400 Ib., allowing for the shaft and handle. EF tools and supplies are needed in the construction of the serviceable con- crete lawn roller shown in Fig. 1. The roller as made by the writer is 18 in. long by .18 in. in diameter and weighs ap- proximately 400 Ib., allowing for the shaft and handle. The molding form, constructed of sheet iron and wood, is illustrated in Fig. 3. The wooden end pieces for the form are shown in Fig. 4. The bottom con- sists of a wooden platform with cleats cut to fit in an 18 in diameter circle and placed so as to hold the sheet iron cylinder. The top is also cut to fit the cylinder and has a crosspiece to support the shaft. Holes for the shaft should be carefully centered in both the base and the top. At the tinner’s, obtain a piece of sheet iron 18 in. wide and long enough to lap over at least 6 in. at the ends when it is bent into a circle of the desired diameter (an 18 in. diameter circle has a circum- ference of approximately 56% in.). This cylinder is then placed between the end pieces and the form trued up and braced, as shown in Fig. 3. To prevent the sheet iron from bulging in the middle, three strands of wire should be placed around it as shown. These are tied loosely at first and then each wire is tightened after the concrete is poured above its level. The shaft should not be less than 1 in. in diameter and should project beyond each end of the roller about 2 in. An old Ford axle is excellent, but if it is to be cut to length, the cutting should be done before the roller is made. The cutting is tedious work with a hack saw, but can be accomplished easier if the temper is drawn first. For the concrete, a 1:2:4 mixture is satisfactory; that is, 1 cu. ft. of cement to 2 cu. ft. of sand and 4 cu. ft. of crushed rock or screened gravel. The largest pieces of rock or gravel should not exceed 1% in. across. Tables of concrete data show that a 1:2:4 mixture yields about 4% cu. ft. of concrete for each cubic foot of cement. Similarly it yields 4% cu. in. of concrete for each cubic inch of cement. The volume of the roller is approx- imately 4,581 cu. in. Calculating, we find that 1,018 cu. in. of cement are re- quired with 2,036 cu. in. of sand and 4,072 cu. in. of gravel. These volumes, of course, will be measured approx- Fig. 3. The form consists of a cylinder of sheet tin held to shape by a wooden top and bottom, which are braced as shown. A brace across top holds shaft central. Fig. 4. The toppiece (shown at the left) is open and has the brace which holds the steel shaft, while the bottom piece (shown at the right) is solid in construction and also has a hole to receive the shaft. APRIL, 1930 imately, using a tin can or bucket whose volume can be estimated to within a few cubic inches. The more accurate the measurements, the less the loss of time, labor, and materials. The sand should be spread evenly on the mixing floor, which may be a wooden platform or a concrete garage floor. The cement is then spread over the sand and mixed in with a shovel or a hoe until the mass has assumed a uniform gray color. The gravel is then added and mixed in thoroughly. When a uniform mixture is obtained, the whole is spread out and wetted down with a garden sprinkler. Be careful not to add more water than the mixture will absorb. Another mixing follows, and water is added a little at a time until a mass of slightly thinner consistency than what is known as ‘‘quaky,” though not quite “sloppy,” is obtained. The im- portance of thorough mixing cannot be overemphasized. Pour the concrete into the form at once. Nothing is better for this purpose than a small coal scuttle. After adding each scuttleful, work the mixture with a rod or a garden trowel to compact the mass, to remove air bubbles, and to bring the mixture into close contact with the form. A garden trowel is especially good for this purpose because it can be worked close to the curved form, shoving the larger particles toward the center, thus allowing the sand and cement to STRAP IRON a xi% Fig. 2. The concrete cylinder has a volume of about 4,581 cu. in. Note handle construction. produce a smooth surface. If possible,. allow the roller to cure in the form from 2 to 4 weeks. If the amount of sand seems to be con- siderably in excess of the amount needed to fill the voids in the gravel, increase the amount of cement. A reasonable increase of cement will also serve to give early strength, so that the form can be re- moved sooner. A mixture of one part of cement to 3% parts of bank run gravel which contained an excess of sand was used for the roller which illustrates this article. Figure 2 shows the assembly of roller and handle. The straps, made from 2 by X in. steel, are held in place on the shaft by washers and cotter pins and are bolted to the wooden handle, which is 2% by 2 in. and should be from 24 in. to 30 in. in length, to Suit the convenience of the user. A heavier roller can be made by vary- ing the circumference and length of the mold for the concrete cylinder.

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930 ose few the me, den The and the lor. | in ed, wn not will and ila han not im- be at Ose ling the to vith ally be ring ter, to on- ded the “ase irly re- t of ivel was this sller naft ited yy 2 . in the ury- the Apri, 1930 POPULAR SCIENCE MONTHLY = A GREAT STEP FORWARD... EVEREADY RAYTHEON TUBES FOR TELEVISION THESE television tubes are of proved performance and de- pendability. The Eveready Raytheon Kino-Lamp, for tele- vision reception, is the. first tube developed commercially that will work with all sys- tems. Its glow is uniform over the entire plate. Its reproduc- tive qualities are perfect— without the need for mirrors or ground glass. Each tube is tested in our laboratories. The Eveready Raytheon Foto-Cell is a long-life trans- mitting tube for talking pic- tures and television. It is made in several standard types, and can be built to your specifica- tions at reasonable prices. If you are interested in talk- ing pictures or television— write to us. NATIONAL CARBON CO., Inc. General Offices: New York, N. Y. Branches: Chicago Kansas City New York San Francisco Unit of and Carbon Union Carbide WCC Corporation EVEREADY RAYTHEON Trade-marks Duane, professor of | What Our $10,000 Prize Will Do for Science (Continued from page 41) A somewhat similar stand was taken by Dr. W. W. Coblentz, formerly physicist of the United States Bureau of Standards, Washing- ton, D. C., whose comment was as follows: “T regard the estimation of ‘achievement in science of the greatest potential value,’ dur- ing the year, as purely relative. The following year it may not appear so promising.” However, unqualified approval came from Ralph Modjeski, noted builder of bridges, and recipient this year of the John Fritz medal for distinguished achievement in engineering. Mr. Modjeski wrote: “TI consider that your creation of an annual award will be a great stimulus to all men of science. It is a most praiseworthy and public- spirited action on the part of your publication.” An interesting point of view is that of Dr. Lee De Forest, radio pioneer and inventor of the audion tube: “We older scientists look forward eagerly to those who will take our places. That they may be duly rewarded for foregoing the more remunerative business world to devote their lives to science, we are grateful to such agencies as PoPULAR SCIENCE MontuLiy. Through the far-sighted vision of such organizations as yours, science has come to be looked upon not only as a future benefactor of mankind, but as a great worker in modern life, to be paid for in the present.” ORDIAL commendation of the award and the motivating idea in back of it was ex- pressed by Dr. William Bowie, engineer and geodesist and Chief of the Division of Geodesy of the United States Coastand Geodetic Survey. “The award,” wrote Dr. Bowie, “should lead to greater support of science and a better re- muneration to the scientific workers and, there- fore, the scientific men of the country cannot but look with great favor and commendation on the forward step that has been taken by your journal.” Equally enthusiastic were men prominent in such widely divergent fields as Admiral W. S. Benson, formerly Chief of Naval Operations; Major General William R. Smith, Superin- tendent of the United States MilitaryAcademy, West Point, N. Y.; and Dr. Carleton R. Ball, until recently principal agronomist in charge of the Bureau of Plant Industry of the United States Department of Agriculture. “T cannot tell you how wonderful and fine I think your generous offer is,”” was Admiral Benson’s comment. “PoPULAR SCIENCE MOonrHLY in offering this generous reward for research work is placing the entire world in its debt.” General Smith sent this message: “Since its founding in 1872, PopuLar SclENCE MONTHLY has contributed immensely towards the advancement and understanding of science, and has thus indirectly increased beyond the power of measurement the mental and physical comforts of living. It now proposes to en- courage scientific accomplishment for the benefit of all mankind by the direct specific award of an annual prize of $10,000 for notable achievement in science. Not only is this gen- erous award highly appropriate as a recogni- tion of past achievement, but it also places in the hands of the recipient funds which may be sorely needed in many instances to continue the work of skilled hands and active brains.” And Dr. Ball wrote: “Scientific research, unselfish in its zeal, has brought rich blessings to humanity but too often has not freed its followers from financial care. This award for outstanding results is in line with the modern trend and the climax of all such benevolent efforts.” Several commentators had interesting sug- gestions regarding the award. Dr. William (Continued on page 138) © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. i i ih al , ert ‘ ba ues " a * syste UM iii SKILLED CRAFTSMEN IN- SIST ON GOOD TOOLS- ALWAYS IN CONDITION. rmnw KEEP YOUR EDGE TOOLS ALWAYS KEEN WITH Carborundum REG. U. S. PAT. OFF. BRAND Sharpening Stones You can do more work and better work when your tools have keen edges. Complete your tool kit by adding a Car- borundum Brand Sharpening Stone. And remember there is a Car- borundum Brand Stone for every sharpening need. From Hardware Dealers or Direct Send for Catalog P-1 of Carborundum Products or, for helpful booklet: “How to Sharpen W ood-working Tools” The CARBORUNDUM Company Niagara Falls, N. Y. Canadian CARBORUNDUM Co., Ltd. Niagara Falls, Ont. Carb dum is the Regi d Trade Mark of The Carborundum Company for its Products

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Make a Clean-up > This eT iiliias in Your Own Cash Business Start to earn big profits immediately sharpening lawn mowers by the Foley Electrakeen System. Hundreds of men made plenty of money last year. Wood- mancy made $25 to $30 a day—Lemont sharpened nearly 600 and got from $1.50 to $2.00 apiece. In three weeks Wal- ter Dambek made , enough to pay for his machine and all expenses. Pp Foley Electrakeen Lawn Mower Sharpener Sharpens all kinds of lawn mowers the factory way in from 15 to 20 minutes and does a perfect job. Customers come back and recommend you to friends because no other method does such good work. There are hundreds of lawn mowers in your own neighborhood. Steady, repeat business year after year. Morse Earned $1520 He writes, ‘‘I started in spare time and found that I was making $5 to $6 an even- ing, so decided to make it a full time pro- position.’”’ Others are doing it too, and so can YOU. No Experience Necessary The Foley is easy and simple to operate. You can learn to turn out perfect work in a short time. Don’t miss this wonderful opportunity to get into a fine paying busi- ness for yourself. Get these easy profits. Send This Coupon NOW FOLEY MANUFACTURING CO. 1440 Foley Bidg., 11 Main St. N. E. Minneapolis, Minn. Please send "me complete information about the Foley Electrakeen Lawn Mower Sharpener and tell me how I can start my own business. RELIEVES - PAIN ( (a QUICKLY Have You a Troublesome Ailment? Infra-Red Rays Aches Relieve and Feine in the for FREE BOOK full information te an Most ailments are due to co e lieve the estion and you relieve the ailment. Infra-Red Rays bring wonderful results. 30 days’ FREE TRIAL. Sent on approval. Easy WM. CAMPBELL CO., Dept. 1041, Alliance, Ohio POPULAR SCIENCE MONTHLY What Our $10,000 Prize Will Do for Science (Continued from page 137) bio-physics in Harvard University, proposed extending the time of work eligible for the award to ten years previous, and also de- clared: “The award should not be given for any- thing that is patented or is to be patented, for such achievements bring their own financial reward.” Prof. T. J. J. See, Mare Island, Calif., astronomer, points out the difficulty of making a satisfactory award: “T beg to say that from the established his- tory of science in former ages no committee, however eminent, can really pick out the great- est potential discovery to mankind. I wish you very good success in the difficult task and can only forecast success if you do not allow common opinion to run it.” HESE difficulties are again emphasized by Dr. Ales Hrdlicka, curator of the Division of Physical Anthropology of the United States National Museum, Washington, D. C., who thinks the judges will face a difficult problem in selecting the prize-winning achievement. “What are to be the main criteria of their judgment,” he asks, ‘‘and how can they man- age to be impartial to all branches of science? Will not the more spectacular ‘achievements,’ and those in the physical and chemical lines, have an undue advantage over those that are less spectacular, or have less backing and popular appeal?” This view is not shared by former President Calvin Coolidge, who wrote: “T note the very distinguished committee that has been chosen to administer this fund and I feel sure it will result in a very fine public service. I wish to express my com- mendation of your efforts and my best wishes for your complete success.” Confidence in the committee’s ability to make a wise and impartial decision is expressed by several other men of note. Dr. Walter S. Adams, director of the Mount Wilson Observa- tory at Pasadena, Calif., comments: “T am especially glad that the membership of your Committee of Award insures that decisions will be made on the basis of broad and far-reaching considerations, and so avoids restriction to purely practical invention.” “The names that appear on the list of the Committee of Award,” wrote Dr. Josiah H. Penniman, the distinguished provost of the University of Pennsylvania, ‘‘are such as to insure a wise selection of the winner. The spirit of this award is that of the founders of PopuLAR SCIENCE MONTHLY and perpetuates the spirit of Benjamin Franklin, who estab- lished the American Philosophical Society for ‘the promotion of useful knowledge.’” In his message of congratulation, Governor Arthur J. Weaver, of Nebraska, said: “The committee of distinguished scientists who are to determine the award is a guarantee of complete fairness and high intelligence in making the award, difficult as it may well be, in determining the future usefulness of an idea or invention.” Fg Dr. Parke R. Kolbe, president of the Polytechnic Institute of Brooklyn, N. Y., expressed himself in these words: “You have assembled a distinguished Com- mittee of Award and I am sure that only good can come through the encouragement which you are thus conferring on the scientific workers of the country.” While endorsing the creation of the award as a desirable means of recognizing excellence in scientific work, Dr. James R. Angell, presi- dent of Yale University, expressed doubt of its ability to stimulate investigators and inventors to greater activity. He said: “T have always (Continued on page 139) ; pres sGreatest G* 7S \ Fu | - 4 “(COMPLETE equipment with Conn instru- ments enhances the musical value of any bead at least. 50 og inns are choice of the world’s greatest artists, Especially recommended to beginners for quicker rogress and greater musical success. Easiest to play, Many exclusive features. Yet they cost no more, FREE TRIAL, Easy Payments onany Conn. Write for interesting book. Tells everything you want to know about your favorite instru- ment. Full color illustrations of most popular models. Write today. C. G. Conn, Ltd. 432 Conn Bldg. Elkhart, Ind. Worlds Largest ‘Manufacturers BAND INSTRUMENTS LOFTIN-WHITE Direct-Coupled AMPLIFIER KIT Approved by the Destgners © WRITE PS. 4 175 Varick St., New York, N.Y. Books for Electrical Workers Experiments with 110 Volt Alternating Current By John B. Adams Shows the amateur electrician how to handle many striking new experiments with appa- ratus, the cost of which is almost negligible. Indicates with simple descriptions and dia- = how 110 volt commercial circuit may handled by the experimenter with perfect safety, without involving the expense neces- sary to maintain a separate power supply. 256 pages. Cloth bound, $1.75 postpaid. Electrician’s Wiring Manual By Frank F. Sengstock A plain operating manual showing by dia- my and clear explanations how to do every ind of wiring from bell circuits to wireless telegraph installations. Invaluable to the apprenticed wireman and to the experie contractor and estimator. Covers thoroughly the questions the elegtrical worker wants answered by the inspector. 448 pages. — in sturdy cloth. Many illustrations 2.50. Electric Motors Direct and Alternating Principles, construction, ration and main- tenance. A _ practical book tee the precsicel man. By David Penn Moreton, B.S.E.E. ge bound. 250 pages, illustrated. Price 1.50. POPULAR SCIENCE MONTHLY 381 Fourth Ave. N. Y. City © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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Apri, 1930 What Our $10,000 Prize Will Do for Science (Continued from page 138) doubted whether financial prizes really exercised any very stimulating effect on the more cre- ative types of mind. At the same time, I am much interested in the proposed annual award.” A similar comment was that of Dr. Virginia C. Gildersleeve, dean of Barnard College: “Tt is pleasant to think that a distinguished scientist should receive this large sum of money, but I rather doubt whether the exist- ence of the prize will stimulate invention and discovery. Somehow prizes do not seem to work this way.” But many other educators voiced unqualified enthusiasm for the step PopuLAR SCIENCE Mon Tuty has taken and the beneficial results expected from it. R. W. M. LEWIS, president of Lafayette College, wrote: “The amount of the award and the breadth of jts Scope will un- doubtedly stimulate much ‘sciéntifit, effort of constructive value. In providing this award and promoting the plan, you dre_rendering service of outstanding value.” Dr. George B. Cutten, president of Colgate University, approved of the prize in this fashion: “The annual award seems to me to be a definite forward step and should prove to be an incentive to a great many men.” One answer to the question of how the award may stimulate creative work in science is that of Dr. J. C. Futrall, president of the University of Arkansas: “Knowing scientists as I do, I believe that many of them will value the medal more than the money and I am sure that much of the money award will be used by the winners for additional scientific research.” “A notable event in American scientific progress” is the manner in which Dr. Edward C. Elliott, president of Purdue University, characterized the institution of the award. The pros and cons of a single award are dis- cussed by several writers. Dr. Gustavus A. Eisen, former curator of the California Academy of Sciences, approves the spirit of the award but comments: “Tt would in my opinion have been better to establish twenty awards of $500 each.” The opposite view is expressed by Dr. D. W. Morehouse, president of Drake University: “TI approve most heartily of the annual award. Its particular appeal lies in the fact that it is of sufficient value to lend great dignity to the enterprise. Poputar SCIENCE MONTHLY enjoys such a reputation that those who do not win the monetary goal will be more than justified by the publication of their work or the recognition of their efforts.” R. JULIAN A. BURRUSS, president of Virginia Polytechnic Institute, drew upon his personal experience as a scientific investigator and educator when he wrote: “Having been for many years directly in- terested in scientific research and particularly in the dissemination of the results of such research and their practical application, I am naturally delighted to learn of the annual award which PoPpuLAR ScrENCE MonrHLY has created. This is an outstanding act.” Dr. George H. Denny, president of the University of Alabama, emphasized the fact that the creation of the award is a logical development of Poputar ScreENCE MonruHLY’s time-tested policy of encouraging scientific and inventive activity. “PopuLAR ScIENCE MonTHLY” wrote Dr. Denny, “has habitually encouraged scientific and ‘inventive effort. Undoubtedly the cre- ation of the $10,000 annual award for the year’s achievement in science that shall be adjudged of greatest potential benefit to man- kind will serve as a (Continued on page 140) POPULAR SCIENCE MONTHLY 139 pen this FREE BOOK and you open the door to SUCCESS “RADIO OU, too, can be ° trained fora big-time radio job... Clip this coupon now and send for this FREE BOOK ... Read it page by page... see for yourself why thousands of fellows just like you are now anaking from $50 to $100 a week... why many others earn as high as $10,000 to $15,000 a year andeven more. This free book gives you 40 fascinating pages of pictures and text, all about RCA Institutes, the only school that is endorsed by the Radio Corporation of America... The school that actually sends you radio instruction direct from RCA... the very source of radio achievement! Easy to Learn Radio At Home in Your Spare Time Letthe RCA Institutes Home Laboratory Training Course give you the real inside facts of radio. . . quickly and easily. Use your spare time to train for success with the remarkable outlay of screen- grid apparatus given to every student of this course. You learn how to solve every radio problem such as installing, repairing and servicing fine sets. This is the training that will help you to make money in radio! RCA Graduates in Big Demand For more than 20 years, there has been a well-paid position in Radio waiting 4 for practically every graduate of RCA Institutes. This is a record unequalled by any other school. Only the vast re- sources of RCA could give you this prac- tical training... Send for this Free RCA Book “Radio ... the Field of Unlimited Opportunity” Start today on the road to Success in Radio. . . Send for this FREE BOOK. 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This school is 30 years old—Coyne training is tested— proven beyond all doubt—and endorsed by many largeelectrical cone cerns, You can find out everything absolutely free, Simply mail the coupon and Jet me send you the big free Coyne book of 150 photographs .. .facts...jobs cece -+. Opportunities, Tells you how many earn expenses while training and how we assist our uates in the field. This does not obligate you. act atonce. Just mail the coupon. BIG BOOK FREE! Send for my big book containing 150 pho tell- ing complete story—absolutely COYNE ELECTRICAL SCHOOL, H.C. LEWIS, President 500 S. Paulina St., Dept. 40-73, Chicago aa SMe RR oe ae A aioe: Mr. H. C. LEWIS, Pres. COYNE ELECTRICAL SCHOOL, Dept. 40-73 SOO S. Paulina St., Chicago, Ill. Dear Mr. Lewis: Without obligation send ! me your big, free catalog and all details j of Employment Service, Radio, Aero- plane, and Automotive Electrical Courses, and how I may “earn while learning.” | NGME coc cccccccccecccccccccccccsesesescessse Addread. acces cccccceccscccccecesecscccsceses ee City. .censcecccccccescess State. .....--se00 OR BO SS AS RE SR SS 7 POPULAR SCIENCE MONTHLY What Our $10,000 Prize Will Do for Science (Continued from page 139) tremendous stimulus to scientific and inven- tive activity.” “The growth and development of our coun- try has been due to scientific investigation and discovery, plus American energy and courage,” was the comment of Dr. J. A. C. Chandler, president of the College of William and Mary. “T am, therefore, delighted to see that it is the plan of your publication to encourage scien- tific research annually.” And Dr. Kenneth G. Matheson, president of Drexel Institute, Philadelphia, Pa., said: “This action on the part of your periodical - will create a concrete interest in scientific achievement which in my judgment will be | far reaching in fruitful results.” Other prominent persons commented as follows: Governor John S. Fisher of Pennsylvania: “The magazine has always kept abreast of the times, and has been a tremendous agency in the spread of scientific knowledge. This last step is most liberal and cannot fail to do much for the stimulation of activities which will yield great benefits to mankind. I most heartily congratulate you on your progressive action.” URGEON General Hugh S. Cumming, United States Public Health Service: “The action of PopuLAR SCIENCE MONTHLY is splendid, the selection of the committee be- yond criticism, and now we trust that Ameri- can research will continue to produce work worthy of high recognition.” Rev. Dr. S. Parkes Cadman, pastor of Central Congregational Church, Brooklyn, | & “The terms of the award are sagacious and far reaching. We surely need the best results of scientific investigation applied to the actual needs of society, and your munificence will stimulate progress in this direction.” Frederick H. Ecker, president, Metropolitan Life Insurance Company, New York: “An award like this, not only in its intrinsic value, but also in the distinction which will accompany it, must surely serve to stimulate scientific experiment and development.” Governor A. W. Norblad of Oregon: “T want to congratulate you upon this real service to America.” Jane Addams, distinguished sociologist, political reformer, and author: “T am very grateful for any effort which brings scientific achievement more clearly be- fore the public and which encourages a better understanding of what is constantly happening in the world of scholars.” Governor Frank G. Allen of Massachusetts: “T am confident that this annual award will effectively'advance bothscience and invention.” Roy W. Howard, chairman of the Board of Directors, Scripps-Howard newspapers: “The honor that goes with the gift of money is in itself worthy of the best efforts of that great body of men and women who are devot- ing their lives to human advancement. The $10,000 is by no means to be brushed aside, however, I understand it to be the largest single monetary prize in America for scientific accomplishment.” OVERNOR FrankC. Emersonof Wyoming: “Tt is a pleasure to commend the project of the $10,000 annual award by Popular Scrence Montuiy for the most valuable achievement in science.”’ Dr. A. T. Poffenberger, professor of psy- chology in Columbia University: “Tf in 1872, when Poputar SCIENCE MonrTHLY was founded, it was considered im- portant to diffuse science, it is a thousand times more important to humanize scientific knowl- edge today. 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930 YF" fic »a ain us is is E er re. Me J Aprit, 1930 What Our $10,000 Prize Will Do for Science (Continued from page 140) ‘annual award announced by PoPpuLaR SCIENCE MoNTHLY will be one effective means of giving scientific work and the scientific workers the attention they deserve.” George B. Cortelyou, president of the Con- solidated Gas Company of New York: “PopuLAR SCIENCE MONTHLY has done a notable thing in instituting this annual award. It will not only focus public attention upon scientists by rewarding the individual scientist but will provide the stimulus of enhanced public appreciation of their invaluable serv- ices.” Governor F. B. Balzar of Nevada: “This is an offer of vast magnitude and should result in arousing a high degree of enthusiasm in making advancement in the scientific world. The personnel of the com- mittee as named is, in itself, a guarantee that the utmost fairness and justice will prevail in making awards.” Rev. Dr. John Haynes Holmes, pastor of The Community Church of New York: “Your announcement of an annual $10,000 prize for each year’s greatest achievement in science is a thrilling thing. Your prize should do in this country what the Nobel Prize does in the world at large.” LEXANDER KLEMIN, professor of aeronautics, New York University: “T believe this award will be of great value in furthering the progress of American scien- tific work both pure and applied.” Frederick A. Kolster, radio research en- gineer: “The creation by PopULAR SCIENCE MoNTH- LY of this annual award merits the highest commendation.” M. M. O’Shaughnessy, city engineer, San Francisco: “T believe it will have a fine tendency in promoting scientific advancement.” Dr. George L. Omwake, president, Ursinus College: “T believe in awards of this kind in college and in the larger realm of human achievement in the outside world as well.” Modern Hotel Is a Huge Machine (Continued from page 23) Lewis called it, required special apparatus. Ele- vators level themselves automatically at the proper floors and doors swing open of their own accord. When a guest pushes a “down” but- ton on the fourth floor, for example, the next elevator coming down automatically stops for him; the elevator operator has nothing to do with it. But if the dispatcher in the lobby sees from the number of stops revealed by a light indicator that one elevator is probably filed, he can speed up traffic by a master control. It countermands the automatic de- vices and lets an elevator go by a normal stop. The dispatcher can talk by telephone with an operator, no matter where the elevator may be. The cars rise 700 feet a minute... On the thirty-ninth floor of the hotel, higher up than any other in the world, is the telephone exchange, with ninety-five operators. But phones are not the only means of com- munication. A pneumatic tube, for instance, speeds the bill for your last minute telephone call downstairs so fast that it is waiting for you when you check out. Then there’s the telautograph, the device that reproduces handwriting at a distance—there’s one in Lewis’s office—to give written records of every request for repairs. Every guest room has a radio. On the forty- first floor we saw the ——— (Continued on page 142) POPULAR SCIENCE MONTHLY 141 TE SRC SEEN NS TT ACTH ee A R. T tf R.T. 1. QUALIFIES YOU TO MAKE MONEY ANDITS SERVICE KEEPS YOU UP-TO-THE-MINUTE ON oe Ze we THE NEWEST In tT, EE a Easy to Get Into this BIG Money-making Work aimeeiieal 460 108125 °4 AWEEK Operator $8 315% | A DAY | ee re OoD “Radio Engineer Rn dentine Sabon OB 8 Right at Your FingerTips WHEN YOU ARE RTI. TRAINED IN RADIO-TELEVISION ~ Talking Prchues Big Pay Jobs! Spare Time Profits! A Fine Business of Your Own! They’re all open to you and other live wire men who answer the call of RADIO. And now come Television and Talking Movies— the magic sisters of Radio. Will you answer this call? Will you get ready for a big pay job NOW and step into a BIGGER ONE later on? You can do it EASILY now. R. T. I. HOME TRAINING PUTS YOU IN THIS BIG MONEY FIELD Radio alone, pays over 200 MILLION DOLLARS a year in wages in Broadcasting, Manufacturing, Sales, Service, Commer- cial Stations and on Board the big sea-going ships and many more men are needed. Television and Talking Movies open up other vast fields of money-making opportunities. Get into this great business where thousands of trained men can easily earn $60 to $100 a week—where even $10,000 a year jobs are plentiful. EASY TO LEARN AT HOME-—IN SPARE TIME of Radio” behind you is EASY, INTERESTING. Only a few spare hours are needed and lack of education or experience won’t bother you a bit. We furnish testing and working ap- paratus ang start you off on practical work you'll enjoy— you learn to do the jobs that pay real money. AMAZINGLY QUICK RESULTS You want to earn BIG MONEY, and want some of it QUICK. R. T. I. ‘Three in One” Home Training— Radio—Television—Talking Movies—will give it to you, because it’s easy, practical, and is kept right up-to- date with last minute information. In a few weeks you can be doing actual Radio work, making enough EX- TRA MONEY to more than pay for your train- ing. In a few short months you can be all through—ready to step into a good paying job or start a business of your own. INVESTIGATE—SEND FOR R. T. I. BOOK NOW Don’t waste a minute. Get the facts about Radio, Television and the Talking Pictures first hand, in the Big R. T. I. FREE BOOK. Learn what this R. T. I. ‘Three in One’? Home Training can do for you. Mail the coupon for FREE BOOK NOW. RADIO & TELEVISION INSTITUTE Dept. 34 R. T. I. trains your head and hands for money-making radio work. y* cyl yo Se i] i] i] t] ; ing me in any way). THE R. T. I. ADVISORY BOARD—of men , actively engaged in the Radio Industry supervises | Name............. the preparation, revision and rendering of training | service. § RARE. 6'6.. cesses : Se me-carominnpureians Learning Radio the R. T. I. way with F. H. Schnell, the ‘Ace’ Let F. H. SCHNELL and the R. T. I. Ad- visory Board HelpY ou Twenty years Radio ex- perience. First to es- tablish two-way ama- teur communication with Europe. Former Traf. Mgr. of American Radio Relay e. Lieut. Com. U.S.N.R. Inventor, designer, con- — engineer. Assisting him is the R.T.1. Advisory Board, com posed of men prom- inent in the Radio In- dustry. Thesemenknow Radio and will help you succeed in their field. Make Money in Your Spare Hours Dear Mr. Schnell:— I enrolled for your course on Nov. 19th. Two days later I in- stalled three antennas that netted me twelve dollars and that is only just the heginning. The course is the most simplified and interesting ever writ- ten on the subject of radio. Anyone wishing to take radio as a life's work should make an analysis of the R. T. I, training. Dewey Lotka, 2175 Leland St., Chicago, Ill. Send me Free and “Tune In On Big Pa’ three-in-one Home 480¢ St. Anthony Court, Chicago RADIO & TELEVISION INSTITUTE Dept 34, 4806 St. Anthony Court, Chicago prepaid your BIG BOOK ’ and full details of your raining (without t-

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“The Boss Was Stumped” “He was trying to figure out a way to apent up the machines. ] could see he was stumped and I asked him if he Lew iy let me try my hand at it. “‘Go ahead,’ he said, ‘but I don’t believe you can help much. Looks like an outside job to me.’ “So I started right in and soon 4 had the whole thing worked out. I could see the boss was surprised. “How did you learn all that?’ he asked. And then I told him J’d been studying at home nights through the International Correspondence Schools. “He didn’t say anything more and I thought he had forgotten all about it until he called me in his office a few weeks later and said he was going to make me foreman and increase my salary $75 a month.” That’s a true story of what spare-time study has done for just one man. There are thousands of others. Why don’t you take up a home-study course with the International Correspondence Schools and epee yourself to earn more money? INTERNATIONAL CORRESPONDENCE SCHOOLS he Universal University’ Box 7680-F Scranton, Penna. Without cost or obligation on my part, please send me a copy of your 48-page booklet, “Who Wins and Why,” and tell me how I can qualify for the or in the subject, before which I have marked an TECHNICAL AND INDUSTRIAL COURSES Architect Automobile Work Architectural Draftsman (] Aviation Engines Building Foreman Plumber and Steam Fitter Concrete Builder Plumbing Inspector Contractor and Builder () Foreman Plumber Structural Draftsman Heating and Ventilation Structural Engineer Sheet-Metal Worker Electrical Engineer Steam Engineer Electrical Contractor Marine Engineer Electric Wiring Refrigeration Engineer Electric Lighting R. R. Positions Electric Car Running Highway Engineer Telegraph eneinece Chemistry Telephone Work Pharmacy Mechanica) Engineer Coal Mining Engineer Mechanica) Draftsman Navigation () Assayer Iron and Steel Worker Textile Overseer or Supt. Cotton Manufacturing Machine Shop Practice Toolmaker Patternmaker Civil Engineer Surveying and Mapping Bridge Engi Woolen Manufacturing Agriculture () Fruit Growing gineer Poultry Farming Gas Engine Operating Mathematics [() Radio BUSINESS TRAINING COURSES Business Management Business Correspondence Industrial Management Show Card and Sign - Personnel Management ttering Traffic Management Stenography and Typing Accounting and C. P. A. LJ English Coaching Civil Service Cost Accounting Railway Mail Clerk Bookkeeping Mail Carrier Secretarial Work Grade School Subjects Spani High School Subjects Salesmanship Illustrating (©) Cartooning Advertising Lumber Dealer SII tall vinsas<eschesdantinasiceieinsinsseeetcaienseneanncibinntatianmananpaadominianneee Street INTIS dcnntssnthaliieUbiadhebbiiidaitininnnadeieesensenxss: tan secehaltiepnp thence gehinndias Nb ciis calililiechabLaaiiasaaniamiianie’ RS EASE i Pa ae TI IIIIIIN 0c i csinicitisinntandnentsinesunadpennseneetnitidd ticiseameniasneannnntion If you reside in Canada, send this coupon to t International Correspondence Schools Canadian, Linnited, Montreal, Canada

ET 4 Fields of real opportu- nity. Big pay—a pean ARCH position or a business of your own. Billion dollars spent last year in one of these fields alone. Train here in Chicago, America’s in- dustrial center. 1, 2 and 3 year courses, Diplomas and B. 8. Degrees. S 4 months’ practical course in Drafting. Other short courses. Earn while you learn. and evening classes. No time wasted. Free Employment Bureau. Low tuition—easy terms. Athletics. —— graduates everywhere. Free 80-pace “Blue Book.” the President, Loony Technical College, Dept. D Ds3, 118 East 26th Str

Enter any time. Day POPULAR SCIENCE MONTHLY

Modern Hotel Is a Huge Machine (Continued from page 141) radio room. It might have been a large com- mercial receiving station. These “five are broadcast receivers,” explained Lewis. ‘The sixth is a powerful short-wave set to pick up European programs.” An operator sat at a panel longer than the room was high. He was operating the sixteen power amplifiers. In all, the room contained a hundred big radio tubes. In case an SOS should interrupt the radio programs, and the broadcasting stations be shut down to clear the way for a ship’s distress signals, two electric phonographs stand ready to fill in. “Four of the receivers give the guest a choice | of as many programs in his room,” Lewis said. “Separate feeder lines run from each to every room—more than ten miles of wire in all. Another receiver gives radio programs through a public address system in the public rooms. In the banquet hall we have a unique device— an ‘echo sound projector’ that gives music just loud enough to be heard, yet not to disturb conversation. It is the first time this has been applied in such a large hall.” HE radio system had other innovations. The management could cut in on a program at any time to make important announce- ments to guests, either in their rooms or in the public halls. The hotel has leased land wires by which special events can be received and relayed to the rooms or public halls. “An- nunciators,” proudly installed a ‘century ago by the Tremont Hotel in Boston, were the fore- runners of this modern mode of hotel com- munication. “Now I’ll show you where all our engineer- ing services come out,’’ Lewis said. He opened the door of a guest room, and we entered an

inviting chamber furnished for two with a | shower and bathroom adjoining. A modern, inclosed radiator was under the window. “One incident will give you an idea of the job of furnishing these rooms,” Lewis said. “Every one, according to hotels custom, must have a Bible. The New York Bible Society, which furnishes those for New York, delivered our order for 2,500 about ten days too late. In the meantime about a dozen guests had called up the office to ask where their | Bibles were.” I noticed the radio, a fifteen-inch cone speak- er, in a corner. A switch allows the guest to make his choice of the four programs. There is even an automatic time switch to tune the radio to any desired program at a given hour. “The walls are soundproof,” Lewis explained. “Your neighbor’s radio won’t disturb you. And the maximum volume is controlled from the central receiving station.” HE guest rooms, of course, were no less carefully engineered than the rest of the hotel. A compartment built into the entrance door allows a valet to*deliver clothes without disturbing the occupant. As an outer door shuts, it operates a signal. The inner door can then be opened, and thus privacy is assured. Running ice water and other comforts are provided. “What do you imagine pleases the guests most?” Lewis asked. After my tour of be- wildering wonders I hesitated. The engineer smiled and pointed to a shiny metal gadget on the wall. “That little twenty-five-cent bottle opener and corkscrew, combined, makes more of a hit, if you’ll believe it, than some of our most ambitious engineering schemes. They think it’s wonderful, and ask where they can buy one like it or whether they can have an extra one as a souvenir. That’s human nature, I guess. The average man, when he turns on a light or opens a radiator valve, doesn’t think of the power plant below that supplies him light and heat. There’s far more to running a hotel than one ever sees in a guest room.” APRIL, 1930 2s 34 Lesson Drawing Course The bi t value you ever saw adverised anywhere .. Haven't you often wished that you could draw cartoons, illustrate some idea, sketch some pretty face, etc.? You can do allof -these things. One of America’s most fa- mous Cartoonists and illustrators has ——e @ great, simple system for success in all branches of Commer- cial Art. This system has revolu- tionized the entire theory of draw- a oe

0} om lerthan learning —* bookkeeping or typewriti Weare now placing this origi learni ng Drawing, Art and Cartooni consisting of 34 lessons with over 500 illustrations, within reach of ee -_ = you will devote a few hou the Course WE ABSOLUTELY GUAR. ANTEE that you will learn to draw and = well before you have half finished vm ourse. If we fail to make this = good, s will refund every cent paid us. us. By elimi- nating alarge office force for answering cor- respondence, expensive catalogs, etc., we are enabled to make a price of $2.98, the nown for a high- rse. asset, no matter what field you are in. Send No Money Just order the Course, and $2. 98

= you order the us a few cents paper, erasers, a payment in full for. the, “entire Course tacks, etc., en and Drawing Outfit. If not entirely to go to bes arth withows any

satisfied, return Rs ve 8 al we will REFUND MONEY. Address: LEDERER SCHOOL OF DRAWING, Dept. 462-K, Chattanooga, Tem, Orders from outside the U. S. A. are payable $3.28 cash with order, Earn MoreMoney as Traffic Manager Are you anxious to earn real money—$3,000, $5,004, $7,500, $10,000 a $0 year and even better? Then become an efficient Traffi c Manager, in your spare time todo quickly, accurately and scientifically what the untrained traffic man can doonly slowly and with many blunders—learn the whys and wherefores of routes, classifications, rates, p re before the LC. mo these and many another accomplishment that marks the difference between the plugger and the specialist, Find out today about LaSalle home-study train ing in Traffic age se lr how it won for Walter Baker the chairmanship of the traffic [ate of the Retail Trade Board of Boston; how it enabled John R. Meeks, of Sheffield, Ala., to increase his income more than 500 per ‘cent; how # helped Samuel Moss, Jr., bill clerk at $55 a month, to organ ize an independent traffic bureau yielding him better than $10,000 a year. Low cost; easy terms. Send for 64- book, ‘‘Opportunities .n Traffic Management,’’ It’s LaSalle Extension University, Dept.482-T Chicags Price

we. best_ makes— 4 Underwood, Remington Royal—also ables —pri ashed to D i half. asy terms) SEND NO MONEY! All late models completely rebuilt and refinished ae new Guvaranteed for ten years Send no money—big Free f catalog shows actual machines in full colors. Get our direct-to-yo pay- < | ment “plan and 10 day tees talel offer. Amazing A values—send at once 231 W. Monroe %& international Typewriter Exch., Dept. 338, Chicag

Government Positions Clerk Carriers, Rural Carriers, Railway Mail Clerks, Postmasters, Department Clerks, and many othem Splendid salaries, easy work, vacation with pay. Only common school education required. Examinations often. Send for our Civil Service Catalog No. 7% COLUMBIAN CORRESPONDENCE COLLEGE, WASHINGTON, D. C. BE A COMMERCIAL PHOTOGRAPHER SPLENDID SALARIES PAID TRAINED MEN AND WOMEN OPPORTUNITIES everywhere f mercial photoeraphers—both en and women. Qualify for ry well-y paid position or open a studie of your own. $i cate ‘way in spare time—Earn while rearing Send today for FREE h tells how vou ca» quickly become

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EXCELSIOR

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1930 Aprit, 1930 POPULAR SCIENCE MONTHLY 143 Ht ere Are Correct Answers = to Questions on Page 46 1. Water cannot be siphoned above the height to which it can be pushed by atmospheric pressure. As atmospheric pressure at sea level is approximately sixteen pounds per square inch, and a column of water thirty-two feet \ high weighs sixteen pounds per square inch, this height represents the theoretical limit. Atmospheric pressure at a height above sea level of 1,000 feet is less than sixteen pounds, so that in this particular problem the water could not be siphoned to an elevation even approach- ing thirty-two feet and it would, therefore, be impossible to siphon it over an elevation 2,000 feet above the original water level. . 2. The pull of gravity on any object is always the same, whether the object is surrounded by air at atmospheric pressure or is in a vacuum. However, an object weighed in a vacuum al- ways is heavier than an object weighed in air at atmospheric pressure, because the object in the vacuum is not buoyed up by the air which it displaces. An object weighed when immersed in water may even have no apparent weight if the weight of the water it displaces is greater than the object’s weight in air. IUNDREDS 4 TRAINED MEN ARE MAKING *60 to$100 A WEEK Why don’t you get into Electricity, too? It’s today’s great Opportunity for you and every other man who is sick and tired of struggling along on small pay. Hundreds of “Cooke Trained Men” who were no smarter than you when they started now make $3,000 to $5,000 a year—and some make even more. LEARN AT HOME IN SPARE TIME Learn with the famous L. L. COOKE “Work Sheet and Job Ticket’”’ Method. It’s simple, it’s thorough, it’s practical. It’s just like actual oy — yet it’s all done right in your own home with the Big Complete Outfit of Tools and Apparatus given to you without extra cost. And it's done in your spare time, without quitting your present job or losing a single hour’s pay. PREVIOUS EXPERIENCE NOT NEEDED You don’t need previous experience—you don’t need higher oe 3. The depth of the water, provided it is deep enough not to interfere with free swimming, y has no effect on the swimmer. It is easier to swim in salt water than in fresh water because salt water is denser and therefore heavier than $5,000, fresh water. Consequently the body of the a swimmer displaces a greater weight in salt : tricity; ; Ps ha water than in fresh water. itu mee eae eg ey — 4. The h f ‘ f aoe A oy or ly clear and simple. We ine pic nothing ike it aaeeneee. Be: the : e horsepower of any type of engine is raining with hundreds of successful graduates; it’s the Training == commonly measured either by means of the that has put many men on Easy Street; it’s the Training for you. nd the Prony brake or by using the engine’s power to GET STARTED -- MAIL COUPON r Baker operate a generator of electricity and then “Cooke Trained Men” are the “Big Pay Men” everywhere. $60 1 Trade measuring the output in electric current. The to $100 a week is what many of them are making. That’s the oot Prony brake consists of an adjustable friction = of . oe Sey you. Get aeeted are the famous L. L. ee | ) Orga» device which can be attached to the shaft, and cney anes Aone. Ae Sag? irwweded ag ™ 0 APR Hee | vice wa upd wage sr ’ for B _“ f 2 soa this friction device is rigidly fastened to an Salk cnapan _—— Book, "Seerste of Dusstes tn Messrtenty arm, the end of which is attached to a spring hicage balance. The pull registered on the balance L. L. COOKE SCHOOL oF ELECTRICITY is figured with the speed at which the Dept. 34, 2150 Lawrence Ave., Chicago, Il. ice shaft is turning. When a generator is used the output of the generator is measured in thou- sands of watts and the result is divided by 746, as 746 watts is equivalent to one horsepower. . ooke of Electricity Bent 34, 3 i580 tawrence Ave., Chicago, ti. Se tively f nd fully prepaid. your book “Secrets of Santa int hetricley with particulars about your Home in Electricity. 5. Water boils at 212 degrees only at atmos- ; Study Course photic pret acta = pace level. In = hot water Name... ..cccccccccccccsccccesscevescevncesessseevccess heating system the weight of the water in the A ALL | a eigeee TERE TS TT 2 CNG oo c1n sina vdccccanncenepeucere Bae dc ccccceccccccce oe pipes and radiators on the upper floor produces ain a pressure considerably above atmospheric Chicas in the boiler, so that it is quite possible for the thermometer to read 220 degrees without any steam being produced. | Training for men of am- 6. Sound travels in air at a speed slightly less Electr ical bition and limited time. — than 1,100 feet per second under average con- course in Theoretical and Practical’ Electrical, aasiig Cc 8) LL ae E is @) U R oS ES Residents of Canada may send cou) Representative. 7 Medbury Lane, ditions. A close approximation of the distance ' H including | Math- a in feet from the listener to the source of sound Engineering chanical Drawing. AT HOME No. 7. can be obtained in the case of a steam whistle, teleal @eachinery. A thereumh nutes "designed to be Carry on your education. Develop power to ini- LEGE, for instance, by timing the interval between the THIRTY -SEVEN VOARO t eM eee RS tiate and achieve. pe hy a first appearance of the steam from the whistle assures you maximum training in minimum time. pm ogg a bay oP aoe OE reas ee and the arrival of the sound, and multiplying Send for free catalog oe oe iathematics, History, Edu- HER the result by 1,075. BLISS A ete. settee relies € Chi a ee, . 0 woul yp The energy lost in friction in any piece of ELECTRICAL SCHOOL The Anivers ty ad Chicago “— machinery is dissipated in the form of heat be- 104 TakomaAve., Washington, D.C. ne studi cause friction always produces the equivalent “vecone a of the wasted power in heat. W ant a 8. There is no eee gn pny 7 _— 9 iwi nc abun ieee: | Steady Job? wn manent or electromagnet for a piece of iron. aie ocd RAILWAY POSTAL CLERKS LCE RTT direct 9. The difference in the brilliancy or sparkle 6 Dept. G269 Rochester, N.Y. np Pveas of a diamond and that of a piece of glass cut in M AIL C ARRIERS s strs: Rush to me WITHOUT 7 like exe exactly the same shape is due to the difference CHARGE FREE 32-page Book 4 ; y a oa with list of U. 8. Government — in the way they refract light. The brilliancy of (City and Rural) £ tions open to men and boy's, and full rt time Somes is caused by the reflection of the $1700 to $3300 Year— , particulars telling how toget a pos ight from many tin (Continued on page 144) SHOULD MAIL COUPON ,° WU SSS aieccceacssens + evegpeee on, Cons : home 3 ORY Cx MEN—BOYS, 17 IMMEDIATELY - — Steady Work. No Layo. Paid Vacations. é BI iso. 600d 40900seneernensuam one

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RES, WR. 2 I ea ee . “- nm 0 ome we aa 7 See om =— Flas a SS. IRI te. ae Sage SE * ig y rgigtr who want facts on the Jobs now open imRADIO You will find the true picture of Radio’s many opportunities for a job in this book. Here are some of your opportunities in Radio. POPULAR SCIENCE MONTHLY Broadcasting Stations use engineers, operators, station measoys. and pay $1,800 to $5,000 a IN ae Radio Manufacturers employ testers, , foremen, coginoms, service mynd oo ers and —-— jobs paying , an $13, 000 a year. ippi ompanies use hun- dreds of Sh give t world wide travel and $85 to $200 a month besides. Radio Dealers and Jobbers (there are 35,000) are continually on the lookout for for pom | service men, en, buyers, managers and Rey $30 to $100 a week for poe! men. Talking ovies as much as $75 to $200 a week to men wi Radio training. th opportunities almost everywhere for you to have a spare time or full tim time Radio Here Are Correct Answers to Questions on Page 46 (Continued from page 143) faces before it escapes to the eye. When light strikes the surface of any transparent substance it is either reflected from the surface or pene- trates through the substance, depending upon the angle at which it strikes. The critical angle for crown glass is about forty-two degrees. The angle for flint glass is thirty-six degrees, and for diamonds about twenty-three degrees. The angles of the faces on the diamond are so calcu- lated that light, once it gets inside the surface of the diamond, is reflected back and forth from one surface to another instead of ing out through the back faces. A similarly cut piece of glass would allow a considerable amount of the light to pass out through the faces on the back and hence it would appear less brilliant. 10. A fireless cooker is simply a very carefully heat-insulated chamber into which the vessel containing the food can be placed after it has reached the boiling point. Because of the ex- cellent heat insulation, the temperature of the material in the vessel drops very slowly from the boiling point, and, of course, cooking pro- ceeds for a considerable time since most foods cook at a temperature lower than boiling. Here Are Answers to Test Appearing on Page 60 The correct word to use in each case in the test given on page 60 is as follows: of your own—to be your own I am showing hundreds every year how to make much more money in Radio en? they could mone in their old jobs. J. > a 3715 S. Kingshighway, St. ou Mo. be from $35 to $100 a week. E. Winborne, 1414 W. 48th St., Norfolk, Va. ., seldom makes under $100 a week now. k proves it. You needn’t give up your job to learn. All I ask is some of your spare time. I will show you ten jobs that you can do for extra money the day you enroll. Throughout your course I'll show you additional plans that are making $200 to $1,000 a year for hundreds of students while taking my course. G. Page, Noel Block Garage, "Nashville, Tenn., made $935 in his spare time while studying. \ My 64-page book tells you where the good Radio jobs are, what they pay, how to get one. It tells you about my rev Radio course of over 50 Lesso Lesson Books, over 40 Service Sheets giving information on servicing different makes of sets, the 8 Outfits of Radio Parts I give for a Home imental Labora- tory, my Lifetime Employment Service and other features. Get it. Read it. Then you can decide one way or the other. J. E. SMITH, Presiden National Radio Institute, Dept. oDOo Washington, D.C. THIS COUPON IS GOOD for ONE FREE Copy OF MY/yjq, VALUABLE BOO rel j J. E. Surrn, President. NO National matte iaahate, — | Washington, DL Dear Mr. Smith: Send pa oe book, “‘Rich ] Rewards in Radio.” I understand this request does not obligate me and that no representative j will call. I I i 1. eaten, given 19. lay, lying 2. bring, take 20. into, taller 3. have, did 21. have, is 4. two, too, to 22. let, laid 5. among, between 23. may, may 6. them, us 24. hopes, his 7. is, his 25. sternly, poorly 8. fiercely, pretty 26. whom, who 9. set, lay 27. numbers, its 10. is, his, himself 28. him, her 11. doesn’t, choose 29. from, from 12. were, was 30. is, are 13. it’s, its 31. almost, well 14. has, its 32. there, her, me 15. as, like 33. they, who 16. might, to 34. his, may, my 17. is, its 35. was, its 18. has, its 36. shall, will Tomb Found in Mongolia May Solve Greek Myth Tue Greeks believed that far to the north of them lived a weird people called the Hyper- boreans, or “Dwellers behind the North Winds.” Archeology has come forward to prove they were right. - A Russian explorer, Professor Peter Kozlov, has just discovered a remarkable tomb in the mountain passes of northern Mongolia, in which he found various significant objects, unspoiled by the dust of passing centuries. He believes that the tomb belonged to an Asiatic person of rank who lived more than 2,000 years ago. The objects brought to light were carved figures of dragons and other animals, tap- estries, carpets covered with hieroglyphs, and pieces of jade. All of them showed the in- fluence of two cultures, the Chinese and the Greek. Probably Greek ideas were somehow carried to the strange people far away in northern Asia, and vice versa. But if so, the contact between the races was so vague and uncertain that the Greeks always regarded their northern friends as a myth. It is thought this may account for the growth of the legend of the “Dwellers behind the North Wind.” APRIL, 193) MNOW=-Become an. Electro-Technician By this Amazing New Method Train the NEW PRACTICAL WAY! Prepare to meet the tremendous de- mand for Electro- Technicians in all branches of elec- tricity. Splendid opportunities. BI for trained men. Now is the time to start. Brings School To Your Home Home Shop-Laboratory worth over $60.00 yours with- out extra cost. Enables you to “‘learn by doing.” Not by texts alone—but with patented new Unit Board System. Brings full-size Electrical Equipment right into your home. Train this fascinating new way under — on of engineers of America’s great Electrical 48-PAGE FREE “coon Write today for passé ey: by ~- book full become an EROSTECHNICIAN” yy eh “the wonderful — ~~ _meeed No obli- gations. Mention age. Dept. 76—Extension Division S§CHODL of ENGINEERING of Milwaukee BEA RAILWAY RAFFIC INSPECTOR PER MONTH EARN UP TO $250 bias expenses Trained men needed in this important profession. Fascinating work; plenty of variety; chance to travel. Advancement rapid with i Repo rt to high officials. WE ASSIST YOU TO A POSITION fpaying $120 to $150 per mo. plus expenses, upon completioa of few weeks spare time home im struction—or refund your tuition Advance rapidly to $175, $200, $250 per mo. 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Aprit, 1930 i First Photo Took Eight Hours (Continued from page 44) indomitable “bulldog of Cormeilles,” most of all, that the world owes its inestimable debt for practical photography. His study concerned the chemical effects of light on various substances. He treated in- numerable plates of glass, paper, copper, and silver, coating them with various varnishes and oils. He experimented with the silver chloride paper of Wedgwood and Davy. He tried the bituminized. plates of Niepce. In the end, he found silver plates exposed to vapor of iodine most sensitive to light. URING his early experiments, Daguerre D worked with Niepce. This retired soldier, who had fought with Napoleon in the Italian Campaign, had made a crude camera, before 1825, using a cigar box and a lens taken from a telescope which had belonged to his grand- father. His plate was made by coating glass with asphalt dissolved in oil of lavender. Pointing the camera out of his window at a pigeon house, he exposed the plate for eight hours. When he applied solvent to it, the dim outlines of the latent image became visible— the first permanent photograph of history. Niepce called his process “sun sketching.” When he died in 1833, he had improved his process very little and apparently had given up hope for the success of practical photog- raphy. But Daguerre labored on, month after month, for six years more, until with success assured, he was able to show his Daguerreotypes to the world. Even then, people were skeptical. When he tried to form a stock company the Parisian public jeered and refused to buy a single share. In desperation, he took a chance, showed his pictures, and explained the secret process by which they were obtained to the eminent French physicist, Arage, who gave his endorse- ment. As a result, the French government awarded Daguerre a life pension of 6,000 francs a year on the condition that his inven- tion should be given to the world and not patented. Once again, the affairs of this re- markable man were at the flood. Hundreds of distinguished men visited his studio and sought to learn his process. NE of these was Samuel F. B. Morse, later the inventor of the telegraph, who first introduced the Daguerreotype in the United States. It is easy to understand the strained, unhappy look of the early “tintype” portraits when it is realized that they had to be taken with the sitter’s face covered with white powder, and with the exposure, frequently lasting half an hour, made in bright sunlight. Professor John Draper, another early Ameri- can Daguerreotyper, introduced a popular innovation. Above the sitter, he placed a tank of clear blue ammonia copper sulphate to lessen the painful glare. For only a decade, from 1839 to 1849, the “tintype” held sway. Delicate, so that the merest touch often marred its beauty, tarnish- ing rapidly when exposed to the air, it soon gave way to improved methods of picture taking. Some of the early silver-coated plates cost as much as forty dollars apiece. No one knows the number of cameras used for pleasure in the world today. Photography has become an inseparable part of present-day life. The last available statistics show that in one year $72,000,000 worth of photographic equipment was produced in the United States. In motion and talking pictures, it provides it aids in virtually every branch of research. In medicine, it has combined with the X-ray to relieve human suffering. In later years, Daguerre suffered from ill health, worn out by his long battle. He died suddenly in 1851, at the age of sixty-three. relaxation for millions. In the hands of science, - POPULAR SCIENCE MONTHLY THIS MAN 1S MAKING 93 The “‘Iideal’’ Lawnmower is a wonderfully simple Sha rpener machine that sharpens all makes of mowers perfectly, scientifically without taking the mowers apart. Just pick up the mower, set it in the ‘“Ideal,”” make a few simple adjustment; and proceed to sharpen. In 15 minutes the mower is ready for the lawn, and you have made $1.50 to $2.00—depending upon the charge you fix. No training required, and machine set up in a few minutes. Plug into light socket and start to sharpen. Hundreds of dull mowers Owners are looking for a place to get them sharpened. No town too small. R. 8. Newcomer, Vinton, Ia., writes: “People come from miles around and other towns to get their mowers ground.” The ‘Ideal’ earns money the year round, too. Sharpens skates— —_— all kinds—perfectly. C. S. Coburn, Little Rock, Ark., "Talent | --... earned enough in 18 months to Sai. for itself and $1857 worth of jonal machinery. FREE book ¢el/s how others do 1, SHARPENING LAWNMOWERS IN SPARE TIME WITH THE “IDEAL” LAWNMOWER SHARPENER You've Man, Why Don’t You Do That? ect tie chance—the same chance as W. T. Moore, Twin Falls, Idaho, who made $1200 net profits 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 efficient lawn- mower sharpener. Use Your Spare Time. Ideal in your basement and earn $4 to $6 an hour evenings and Saturday afternoons. E. W. McCormick, Saginaw, Mich., writes: ‘‘Five years ago I bought an Ideal Shar ener on which I have ground over 5,000 lawnmowers. In the last few weeks I worked at my trade, machinist, full time 9 hours a day. I also ground 97 mowers which netted me $114.10 clear gain.” You Make Money Right Away. 2°.°;,."- Stillwater, Minn., writes: “We set the machine up 2 weeks If you work at a trade, put an Friday; since that time have sharpened 102 mowers.” H H are waiti t ‘o in your local ity — sh ~ >on on That's close to $200 in Kearney’s pocket for 2 weeks, work! Our Free Book Tells You How [¢°* me others have made spemocives independent—buillt substantial Permanent BIG PAYING businesses with this Ideal \ Grinder. Send for this book today—It’s free. SIGN THIS AND MAIL TODAY a SITES EAE SOA _ THE FATE-ROOT-HEATH CO. 933-956 Bell St., Plymouth, Ohio, U.S.A. ! Send me the book that tells me how Ican make my { spare time worth $4 to $6 per hour. ‘ TNs 50.068 thas eanesen card prese peat tsteuan ] PID occ cc deciecsccssntcccaebancbionddesene i PP ee ee eT eee GOR in 5:5:0:0:93:,0%00 500 f BOYS! MAKE Bic MONEY BUILD BIRD HOUSES Here's a real money maker. With my simple instructions any boy can build and erect Grandpa Bird Houses. They sell at $2 to $97.50 each. $2000 worth sold in Oak Park, TIL. in a year. Send $1 for my big collection of work sbop plans for boys who want to have fun and make money building - a bird houses. Valuable information about song birds and tips and advice on making sal es included P " _ GEORGE J. BREIDERT 1047 N. Elmwood Ave., Oak Park, m. Course in This simplified, complete Course—specially prepared for home study by leading professors—meets all ments for entrance tocollege, business, and professions. Money Back When You Finish If Not Satisfied AMERICAN SCHOOL, Dept. H-448 Drexel Avenue and 58th St., Chicago Send me full Information on the $ checked and how you will help me win success In that line, ..-.Architect ....Electrical Engineer .---Bulldin Goutroster . -—- Beneral Education ona n ned --.-Civil Engineer «-.- Mach. Practice Struct .-.. Mechanical Engineer High School Business | Manager Steam Engineer ----Bus nail ...C. P. A. & Auditor .--.Draftsman & Designer ---- Bookkeeper ...- High School Graduate Name. Age. OR oie ncinccsd sso rsnczndosuleccsenagcassbckasgueemnaiieaiaiatt Town. Es To Men who want to get into AVIATION The men who enter Aviation today will be its leaders to- morrow. Why sit back and let others step in ahead of you? No matter what you've been doing up to this point, Aviation has a place for you —and a real future. But you must be trained for it. ARE YOU 187 m Ht yee want to size uP Aviation in os 9 of SOS. foe te pation, we'd like to hear from pg to South America, first other things, the book ex how Walter to fly sour Hinton w ive you a thorough course of se Aviation right at home. After Water Hixtox groun free | _ you've finished this course, you'll be fitted to during the War. secure and hold down 2 gous job or miles of flight, instruc- take up flying i at reduced tion of thousan o rates at a field which Hinton will pick men are behind the art a yg methes of ining i ® & proved success. bs Hinton offers for the book if you're eighteen or over and rious. ee Aviation Institute of U. S. A. Walter Hinton, Pres. 1115 Connecticut Ave., 1 Washington, D. C. 302-F 1 I'm serious about Aviation. Send a g FREE copy of “‘Wings of Opportunity.” £ Ss tscedseetesdebenstenreea Age . Ds GORE» asinine pian bieeatemdione fe == — “——a- ooneneasesenseuwseund

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PED wR TR PRDIF AE More and more is electricity lifting the weight of labor from the shoulders of man. If you are not satisfied with your present job, become an ELECTRICAL EXPERT and free yourself forever from the discontent of low wages. You do not need any previous training. Any man who can read and write and use his hands can become an electrical expert. Here is Your Opportunity The NEW YORK ELEC- TRICAL SCHOOL pre- pares you for the BIG PAY profession. First you learn the theories of electricity and then you put them into actual practice. You solve each problem with your own hands. When you have completed your course at the NEW YORK ELEC- TRICAL SCHOOL you can go to any part of the world and be sure of a good living. Write today for the 48-page booklet giving full infor- mation on how to be an electrical expert. NEW YORK ELECTRICAL SCHOOL 40 W. 17th Street, New York proce o MAIL _TODAY------— ' THE NEW YORK ELECTRICAL SCHOOL 40 West 17Te Street, New Yorke Please send me FREE your 48-page booklet. It is understood that this request puts me under no obligation.

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POPULAR SCIENCE MONTHLY

I’ve Seen a Lot of Flying in Twenty Years (Continued from page 59) allow greater protection for the pilot as well as superior streamlining, tractors, with propellers and motors in front, have supplanted the push- ers. Motors and gasoline tanks are still placed close together on many ships, increasing the fire hazard in a crash. This is something pilots would like to see designers change. I have flown with many kinds of motors. Each had a sound of its own. I can close my eyes and hear the characteristic song of half a dozen engines: the clatter of the Anzani, the whine of the Gnome, the thunder of the Benz, the howl of the LeRhone, the staccato volley of a Challenger, and the smooth, deep- seated roar of a Whirlwind. Since the war, air-cooled motors have achieved supremacy. They have proved as reliable as water-cooled engines, are lighter per horsepower, and have no water-cooling system to get out of order. HE French Gnome was the Wright Whirl- wind of 1911. It held practically all the rec- ords. This curious motor was air-cooled and spun around with the propeller. It was lubricated with castor oil. In a Bleriot, the excess oil shot back, hitting the pilot in the face. Frequently we came down from the clouds covered with castor oil. When it got in our eyes, they pained for hours. Another eccentricity of the Gnome was its sticking valves. If the engine got hot, the spring on the intake valve would lose its elasticity and the valve would stick. If a rocker arm on one of these whirling engines broke, the ship came down with its cowling torn to pieces. The gyroscopic effect of these spinning mo- | tors had to be watched on early planes. In | 1912, Weymann represented America in the | Gordon Bennett Cup Race. He flew a 100- horsepower Gnome-Nieuport. Spectators saw his left wing dip several inches every time he cut the engine in and out on a turn. I once saw a freak accident happen to a mechanic who was cranking a Gnome on an old Farman pusher. The pilot shoved the throttle clear ahead by mistake. The motor started with a roar. It tore the machine out of the hands of those who were supposed to hold it. The tail struck the mechanic from behind. He rolled a dozen yards like a batted ball before he could find his feet. WENTY years ago, when flying was just beginning, the papers were fullof wildstories of the imagined adventures of noted skymen. In those days there were a dozen flights of imagination for one of an airplane. But I used to believe every one. I swallowed them whole. I remember two. One told how Vedrines, the idol of France, had been attacked by a giant golden eagle high over the Pyrenees during the Paris-Madrid race of 1911. According to the account, he battled for his life, his frail Deperdussin monoplane rocking from side to side as, with a small penknife, he fought off the infuriated bird. The other told how André Beaumont, the famous Bleriot pilot, almost lost an eyelid. According to the story, a plane swooped close above him in the air, and as he looked up, a gale of wind caught under an eye- lid, puffing it up like a miniature balloon. He thought it would be torn off before he could lower his head—anyway, that’s what the published report said. Such tales were more creditable in those days than now. There were no windshields and pilots sat exposed to a gale of wind. Fre- quently they wore no goggles. On my first Farman, I was perched precariously on a sort of ladder stuck out in front of the lower wing. During the first flights, I remember, the wind pushed back my cheeks. I felt I was grinning all the time I was in the air. Later, I seemed to develop muscles to (Continued on page 147)

APRIL, 1930 FcarnAVviATION WHERE LINDBERGH_STARTED! ~ 0+)

Quick Success > for Lincoln Graduates! EN, aviation offers you remarkable opportunities for a big future. Capable trained pilots and mechanics are in demand at good salaries. Our graduates take the better positions because of the superior training given them at this school. Read below what some of our graduates say. Read These Letters! Demonstrates Planes— “Y3irvers complete instruction, I have secured a position with an aircraft company in Lincoln, demonstrat- ing planes. It peye mea good salary, and en- Me me to build up enough hours’ solo required for my transport pilot license at no expense to myself.” —M. S. Smith. I traveled over Substantial Salary—i1; the U. 8. in- vestigating aviation schools and airplane fac- tories. I finally selected the Lincoln School, and - glad I picked it. After graduation, I had o difficulty in getting a good position in one of Lincoln’ s aircraft factories. I get a substantial salary and assurance of promotion.’’—W. pew 1 ed Lincoln! Y earn at Lincoln! ou, Lindbergh— too, come to Lincoln! Get outstanding, superior training at the Lincoln School. Complete, practical Pilot and Ground Courses. Plenty 7 new-production planes. Extensive ground training facilities. Expert instructers. Planes and transport pilot in- structors government-licens Get FREE Aviation Book! Contains full information about Lincoln School. Tells story of “Lindy” at Lincoln. Chock full of vital aviation facts. Tells about Big Money opportunities. Write today, stating age! LINCOLN Airplane & Flying School 219 Aircraft Bldg. Lincoln, Nebr.

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in the floor of the cockpit between the pilot’s feet. We always carried a small stick handy. If the flare stuck, we poked it out with the stick. Three minutes is the usual length of time a modern flare burns. It gives off a light equal to between 300,000 and 400,000 candlepower. It usually released at an altitude of 2,500 eet. When the “Circuit of England” race was held in 1911, bonfires were lit along the course. The smoke guided the flyers by day and the blaze led belated racers to control points at dusk. Those bonfire beacons formed the beginning of the (Continued on page 148)

POPULAR SCIENCE MONTHLY

tf you are ogtious~went oe oorn money as a dra an—copy and mail to me. If I think you show talent you, direct from my drafting a handmade Airplane blue print in three views with all main partsnamed | and explained. Also FREE my two “M Raising ” and ** Draftsmanship ” They tell all about this sosthed by chic | treks yousightin pert wi you right in own home. No matter what your school ing or what you aredoingnow clip the coupon and kara what I can do for you Automobiles, Electricity vation, 4 a ries of others. E that , drafting room. No wonder there is such a big demand I Train You for trained men. You can prepare for one of these At Home DRAFTING _ fing your present joo Ti'giesou practical casing No need te lara ! or AND DESIGNING [avswrained men who are making $3000 $9000 Jee Net sly Got cou ese wae he. ne oe ee ee today. Coop practical drafting Pie pmee , he sketch and mail with coupoe ene og ded— tra Char, » iaont tae damaie of Oe Aman CMPLOYMENT SERVICE 222° ha After training you, | help you get a good job without ive a ete course ‘ting Toth ing you a cent for this service. Employers come to ? 0 act quick! will include this special know that Dobe Trained Men make good

3 I If You Earn Less Than’70 a\Week Engineer Dobe, piv. 13-64 : 1981 pry 9 Sve. Cscage am attaching sketch of Airp . Send me the three-view blue » off Fone Hay as offered. Also your twe Name Aoe

A definite program for getting ahead financially will be found on page four of this issue. “ore |PNSASRCEDE SHOOTER J easily made taking orders for Jiffy ¢ Glass Cleaner—the amazing new liquid that cleans windows, wind- shields, show cases, etc., in a few sec- ond« without soap or water, Everybody a Steady repeat business. Chance for ery day. No or ce ‘onderful unity for men and everywhere. Write today for Profit-Sharing Plan. AMERICAN PRODUCTS CO. 5679 Monmouth Cincinnati, 0. TRAVEL FOR “UNCLE SAM” RAILWAy $158.00 to $225.00 MONTH POSTAL CLERKS MAIL COUPON BEFORE YOU LOSE IT =a eo ee Franklin Institute Dayt- G-267 ter, N. Y. # Sirs: Rush to me without c ange, copy of 32- book, “How to Get U. 8. Government o — @ eek D i Steady Work—No Layofis—Paid Vacations yuriculzrs telling how oes hen Many Other Government Jobs —Common Education Usually Sufficient

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148 % % Who Else WANTS A GOOD DRAFTING JOB? During the past few months we have placed hundreds of former mechanics, office men, build- ing-trades workers and even beginners in fine Drafting positions — with Contractors, Archi- tects and in big manufacturing plants all over the United States. These men come to us because they are dissatisfied with their earnings and future prospects. New they are doing workthey like—making good money—and have a real chance to advance still further. Why We Recommend DRAFTING It will pay you to investigate Draft- ing. You'll find many of our most successful Contractors, Engineers, Superintendents and Executives STARTED in the Drafting room. Theworkis interesting and pleasant. The hours are easy. You'll work “Thanksforhelp- With a wonderful bunch of fellows. ing me get a Salaries range from $35 to $50 a Drafting position week for beginners, up to $5,000 a ear and more for experienced week. raftsmen. And best of all you can Oskar R. Ludwig learn easily in your spare time, right Gary, Ind. in your own home. was) 4 Jobs When You’re Only Half Way Through! We have recently develo a re- markable placement service which enables us to find good positions for students when only half way i} through the course. T men are j making RAPID progress because they are combining spare-time “I have obtained study with practical experience on & position as a the job. Over 70,000 Drafting positions r ‘$ | Peta vertinnd Guring tho pest year. a ate your Here is one of the biggest fields you ald in Fo epno | can get into. Right now we oa LS nvery making an interesting proposition Maurice N, to ambitious men—mail coupon for Bareham complete information. American School Dotti, Pixs! Avenue Se ee ew eek ee mee se ee eS ee AMERICAN SCHOOL, Dept. . Drexel Ave. and 58th St., Chicago, Ill. Please tell me, without cost or obligation, about your training and employment service in line marked X below. POPULAR SCIENCE MONTHLY 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. Easy Lessons Even if you don’t know one note from Playin Half Hour fter you get the easy motions you play harmon: ous another, the 52 chotds with very printed léssons and little practice clear pictures make it easyto learnquick- nowledge needed, ly, Pay as you play, GIVEN when you enroll —a eet toned HAWAIIAN GUI WRITE AT ONCE for attrac- tive offer and easy terms. postcard will do. ACT! f and cther No extras-everything included The same h instruction on Tenor Bea cabs igia Noner Gate Butte Bann kuin inf \ Vell-known instructors. Write for full information. FIRST HAWAIIAN CONSERVATORY of MUSIC, Inc. 9th Floor, Woolworth Bidg., Dept.246, New York, N. ¥. Approved as a Correspondence School Under the Laws of the State of New Y¥ork—Member National Home Study Council, I’ve Seen a Lot of Flying in Twenty Years (Continued from page 147 lighted airways of today. Now a night flyer in America can follow a chain of flashing aerial lighthouses from coast to coast. There are more than ten thousand miles of lighted air- ways now in the United States. In the dark, familiar landmarks are blotted out. Main highways can sometimes be dis- tinguished by the stream of automobile head- lights, visible from the air. A railway can be located by the glowing windows of passenger coaches or by the red glare on the smoke of the engine when the fire box door is opened. Steel mills throw up a lurid light on the sky that is visible for many miles. When the early night air mail pilots were blown off their course by storms in Ohio, they used to find their way to Cleveland by following the red patches on the sky above the steel mills of Sharon, Youngs- town, and Warren. NE time, I arrived at an air field after dark. Under a cloud, near the edge of the field, the ship suddenly rocked and trembled. It had struck the backwash of another plane which had crossed ahead. We had just missed in the dark and neither pilot had seen the other. That was before riding lights—red on the left wing tip, green on the right wing tip, and white on the tail—were required on night- flying planes. An even more thrilling escape from a col- lision at night was reported a little more than a mas ago by one of the Pitcairn pilots. He opped off from the Philadelphia field carrying the night air mail for Atlanta. It was a clear night with plenty of stars, but no moon. He was flying at 2,000 feet. Suddenly a gray shape loomed up ahead. At first he thought it was a small patch of cloud. At the last minute, he decided to climb over instead of flying through. He pulled back the stick, zoomed up, and when he looked down—caught his breath. Below floated the huge silver body of the Navy dirigible Los Angeles, returning from a training cruise. After that narrow escape, the Navy issued orders for the big airship to steer clear of the night air mail lanes. The smallest ship I ever flew had an eight- horsepower motor. This gnat-sized baby plane landed at about twenty miles an hour. It seemed no faster than a walk after coming down for hot landings in Fokker and Nieuport pursuit planes. They often touched the ground going like greased bullets. The largest ship I’ve piloted had a total of a thousand horse- power. The steadiest ship I remember was an old Voisin. It was no more streamlined than a hayrack. The hundred wires that braced its wings would all vibrate in flight, each produc- ing the resistance of a broom handle. The ship was too stable to be safe. It couldn’t be maneuv- ered quickly enough. The most unstable plane Iever flew was the one I built myself just after I learned to fly in the Batkan War. Piloting it was like walking a tightrope in the wind. EN I used to act as test pilot for a new machine, I never knew whetlier the ship would be a bird or a groundhog. To know if it would fly, you had to try and see. Now, wind tunnels and kindred tests show a design is aerodynamically correct before the plane is built. When it is turned over to the test pilot, he knows it will get off the ground. - Fifteen years ago, designers didn’t know the strength of various materials as they now do. Ships were builf stronger than was necessary in some places and not strong enough in others. Each year, planes become stronger per pound of weight. The other day I dove a Curtiss Hawk at almost 250 miles an hour in perfect safety. A few years ago, I saw a pilot try to do that and he washed off his wings. At that time I was up with a student (Continued on page 149) APRIL, 1930 Dyke’s Aircraft Engine Instructor This book ig a complete edu- cation or train- ing in the con- struction, maintenance and repair of NDYKE'S the power engage f equipment in aN yw =6use On modern f aircraft. It explains the Wright “Whirlwind” Engine — the “Wasp’’—the Curtis — the Fairchild Caminez_ En- gine without crankshaft or connecting rods —Inverted ngines which run wu side down—the Packard 24. Cylinder En- gine and others, Also miscellaneous equipment such as carburetors, magnetos, starters, aeronautic instruments, etc. Colored Master Charts and many unusual illus- trations make very clear the construction of a typi- cal engine. You are shown where troubles are likely © develop and what to do to correct or prevent them. Nearly 400 pp.—7x10 inches—400 Illus. Flexible binding. Price $5.00—Prepaid. Diesel & Oil Engineering Handbook J. ROSBLOOM Fourth Revised Edition The impor- tance of this book can best be empha- sizedwhen the trend of Diesel engi- neering for land, marine, locomotive, automotive and other branches of power pro- duction is considered. Written in ractical anguage, with hun- dreds of tables and formulae. Profusely illustrated with color 2 My AP and plain views. Complete course of instruction in leading types of Diesel engines. | 650 pages; size 5x7”; flexible binding. Price $5.00—Prepaid. Book Department POPULAR SCIENCE MONTHLY 381 Fourth Avenue, New York City | DIESEL’ €-o1 | ENGINEERING HANDBOOK | hogs ‘Today — Write for my FREE BOOK. I cas make a pen oi at home during spare time. Write for my FRE! BOOK, Howto 2 Good Penman."’ It contains s how others mastered System. Your name will be elegan card if you enclose stamp to pay postage. Write to- day for Book. F. W. TAMBLYN, Kansis Cha Mon U's. A. information REE Send us your name and address for full information ré- garding the Aviation and Airplane business, Find out about the many great opportunities now open and how we prepare you at home, during spare time, to qualify. Our new book Opportunities in the Airplane Industry also sent free if you answer at once. AMERICAN SCHOOL OF AVIATION Dept. 1364 3601 Michigan Ave. CHICAGO a te: tee ee ot tes te i a an ll te i. ii ee e- e i i

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930 a on 53 e 3 Pp F aRoS? Bottee |; Aprit, 1930 —_—— I’ve Seen a Lot of Flying in Twenty Years (Continued from page 148) near Curtiss Field. Two Army pilots were stunting a thousand feet higher up. I was in a flipper turn, banked vertically to the ground, when I looked up. I saw the Army plane come down in a vertical dive. The pilot pulled out too abruptly and the wings broke. They jackknifed back along the fuselage and, like a yellow meteor, the plane shot past a couple of hundred yards away. I could see the men fighting to get free. A hundred feet below, they kicked loose. I began to breathe again when their parachutes blossomed and they floated down to safety. When we first began using parachutes in planes, the jumper used to crawl down and hang by his hands from the axle of the landing gear. When he was ready to drop, he just let go. ROBABLY the two greatest stunt flyers of the early days were Lincoln Beachey, the American, and Adolphe Pegoud, the French- man. The latter was the first man tOfly up- side down and to loop the loop. He was a temperamental artist of the sky. Before he would leave the ground to perform his loops, he always demanded a pint of red wine. He trained for his stunts by placing a monoplane upside down on tall wooden horses at the Bleriot factory. He strapped himself in the seat and hung head-downward for so many minutes each day. Gradually he increased the time until he could hang in this position for long periods without discomfort. Then he went up, made his first vertical letter S in the air, and became famous overnight. The first plane I flew had no instruments at all. My latest ship has a dozen dials and gages on the instrument board. They make possible long and “blind” flights through fog. In ordinary flying, however, the instruments should be glanced at occasionally rather than watched constantly. “Bubble chasers,” stu- dents who learn to fly by instruments alone, never make satisfactory pilots. After all, in- | struments show what is happening—after it | has happened. Most flying should be done by “the feel of the ship.” Recently, a greenhorn pilot in Montana “cracked the throttle” for starting the motor and shoved it almost wide open. Without setting the brakes, he swung the propeller. The motor snorted, took hold, and the ma- chine charged down the field, a runaway ship. According to newspaper accounts, it took off, flew for nearly five miles by itself, and came down in a large hayfield with no other damage than a broken propeller. Such a flight is entirely possible. Given half a chance, a modern ship will fly itself. Twenty years ago, a plane wouldn’t keep going a minute without a pilot. Early machines didn’t want to fly. The pilot had to make them fly. In a nutshell, the difference between the planes of the past and those of the present is this: In the old days, you had to fly your plane; now you have only to pilot it. Not long ago, I flew for nearly two hours on a cross-country trip with my hand off the stick. Most of the time, I leaned back on the cushions and looked out the cabin window at the scenery. Occasionally I would tap the stick to one side or the other with a forefinger. That is the sort of flying we used to dream about—twenty years ago. EXT MONTH :—Jordanoff writes of stunt flying .and explains why a pilot’s life may depend upon his skill in performing aerial acrobatics. You will not want to miss this thrilling chapter from the life of a flyer who in war and peace has faced death hun- dreds of times. POPULAR SCIENCE MONTHLY 149 ‘To those who think Learning Music is hard- Perhaps you think that taki music lessons is like taking a dose o} medicine. It isn’t any longer! As far as you’re concerned, the old days of long practice hours with their hard-work exercises, and expensive personal teacher fees are over with. You have no alibis whatsoever for not making your start toward musical good times now! For, through a method that re- moves the boredom and extravagance from musical lessons, you can now learn to play your favorite instrument entirely at Peegactoe 7 om | a private teacher—in half the usual time—at a — tion of the usual cost. Easy As Can Be The lessons come to you by mail from the famous U. 8S. School of Music. They consist of complete printed instructions, diagrams, and the music you need. You're never in hot water, First you are told how a thing is done. Then a picture shows you how, then you do it yourself and hear it. No private teacher could make it clearer or easier. Over half a million people en to pla a br | mod ern way—ani it easy as A-B-C. For _ LEARN TO PLAY | get that old-fashioned BY NOTE idea os thy you = cial ‘‘talent.” t Mandolin ———-— pooy oe list of PO a on “ cI ments in the panel, de- Viclin } amg cide — one on vent “ to play, an e U. 8S. Banjo Trombone School will do the rest. Or Any Other Instrument No matter which instru- ment you choose, the cost in each case will aver- age the same— just a few cents a day. Send for Our Free Book and Dem- onstration Lesson If you really do want to play your favorite wo strument, fill out and mail the coupon asking for our Free Booklet and Free Demonstration Lesson. These explain our wonderful method fully and show you how easily and quickly you can learn to play at a | = pense, ie wo are puppned when needed—cas credit. U. 8. School of New: York rk City. usic, 84 Brunswick Bids, U. S. SCHOOL OF MUSIC, ‘64 Brunswick Bids. New York City Send me your amazing { ree book, “Music Lessons 1 Your Own Home,” Crane, also Free Demonstration Lesson. h introduction by Dr. Frank is does not put me under any obligation. « dpvtadt tie x fiatherteins one coneees 060+.0.0thaee¥ this Inst.?. ..«....0. DRAW CARTONS Turn Your Talent Into Money Cartoonists earn from $50 to $250.00 per weekx—some even more. Remark- able new Circle System of Drawing cenches you in half the wenet time. Send for booklet and sample lesson plate explaining full deus of the Course. No salesman will call. THE NATIONAL SCHOOL OF CARTOONING 615 Penton Building Cleveland, Ohio AUTO Beery city, town, and farming community is MECHANICS ph my A oO McSweeny ,Auxte;* Tractor & ry Chester at 30th St. weenyaA On. on Schools A-12-W Memphis, Tenn. A definite program for getting ahead financially will be found on - page four of this issue. SENT As-w ae ‘ACTS that may save woman [p/ IN ELECTRIC Pilg) REFRIGERATION America’s newest and fastest growing indus- try—Electric Refrig- eration — needs trained men to fill service, sales, factory and executive positions at salaries up to $50 and $200 a week. Amazing new easy training quali- fies you quickly at home in spare time. Endorsed and praised by General Electric, Servel, Kel: inator, » Zerozone and other manufacturers. Earn As You Learn FREE! New Easy Way Unlike ordinary schooling. New book containing Fascinating—practical. No study drudgery. Charts, dia- resent t: f grams and pictures help you. ane Easy terms. Money-back | how easily you can agreement. Free employment | win a big pay job. service. Get big new book of [| Write TODAY! facts—FREE! UTILITIES ENGINEERING INSTITUTE 4403 Sheridan Road, Dept. 240, Chicago, Ill. Major B. Q. ones famous as_ the safest trainer of air men in any army—gives you the secrets of the air he has learned through fifteen years of practical flying, and success- ful experience as an instructor. How to E25 4 This Famous Book Gives You Your Groundwork This graphic guide provides the quickest, surest route to big pay in Aviation. Its knowl- edge shortens the road to a pilot’s license. Takes you over a plane inch by inch, instruct- ing you in the use every operating part, every instru- ment. It teaches you all about the art of flying, tells the secret stalling, spinning, cross- country navigati how to taxi, a climb, turn, bank, 200: mmelman, delle—HOW. TO FLY. Menin the big air colleges: use this pers Manual to get ready or flying. Send the om : and get a —_~ for nccdnation: ou th _— no money. Mail for FREE Examination Ronald Press Company, Syeeees, Dept. M305 15 East 26th Street, New og od FREE examination by Malet Jones. ae satisfied I will return pete v3 = of Watandof aay will remit $3.00 which paye in full for the Poe eee ee ee Ieeee esis eer eee) Rush pew we wre eases > & i

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ES ee ——. we et ee me. ve _awUE os ke oncea man= who stood on a big sea chest, sothe fable runs, and scanned the hori- zon througha telescope —anziously on the lookout for the ship that was to bring him fortune. Slipping, he upturned the lid, only to discover that the battered chest was filled to the brim with gold and jeweled treasure. Only a fable—granted. But what a world of truth that fable holds for the man who is really in ear- nest to advance his fortune. But hasn’t it occurred to you that you can make your opportunity right where you are? Thousands of others have turned a rut into a road—why can’t you? For instance, not much chance for Harry L. Baker, he might have said, when he started as shipping clerk at $6 a week in 1910 with the Owen Greeting Card Publish- ing Co., Elmira, N. Y. But he made up his mind to grow with his company, and today he is Secretary and General Manager of this firm, now thirteen times as large. Not much chance for J. L. Aldrich, it seemed, when he started with the Monroe Calculating Machine, as order clerk. He had never sold goods; had never held a managerial position. Today he signs himself ‘‘Dis- trict Manager”’ of this great organization. The future didn’t look so good for J. H. Bryson, of Tenn., clerking in a grocery store at $40 a month. To- day he is Secretary-Treasurer and General Manager of his own firm and doing a nation-wide business. “Be ready for your chance, and thus make your chance”’—that was + 8. ee ol i ong the ion: “How can I win motion?’’ when he was rm $25 a week. Today he is Sales and Adver- tising Manager of Society Brand Clothes, Ltd., of Canada. . Forget the Telescope Your Opportunity Is Here and Now fust you scan the horizon for some far-off oppor- je ae the same LaSalle home-stud toalning that helped these men is available for you Will you wear your heart out waiting for (a istant opportunity that may never come—or wi 4 it just as thousands of others have found it, close at home, with the aid of the coupon, and with- out cost or obligation? ' ‘ The time to pecrpe for peees is this moment, and the time to act is—NOW. eae These 4 men clipped a coupon like this aus LASALLE EXTENSION UNIVERSITY The World's Largest Business Training Institution Dept. Ti I only had a chance,” you say. Chicago I should begiad tolearn about your Salary-increasing plan as applied to my advancement in the business field checked below. Busi M a t Higher Accountancy Traffic Management Modern Salesmanship Railway Station Mégm't Law: Degree of LL.B. Commercial Law Industrial Management Modern Foremanship Personnel Management (J Business Englis Bankingand Finance (Commercial Spanish Modern Business Corre- () Effective Speaking spondence UO Stenotypy-Stenography Expert Bookkeeping 0) Telegraphy C. P. A. Coaching () Credit and Collection Railway Accounting Correspondence Paper Salesman’s Training POPULAR SCIENCE MONTHLY Harbors for Motor Boats (Continued from page 57) A third plan would convert unused steam- ships into breakwaters for boat harbors. This plan is proposed by the New York Yacht Basin Association, an organization of motor boat owners. It would utilize several of the old ships of the U. S. Shipping Board Fleet which have lain idle at their anchors nearPeekskill, N. Y., since the war. Several of these boats, according to Montagu Worthley, secretary of the Yacht Basin Asso- ciation, could probably be purchased for as little as $30,000 apiece. They would provide the equivalent of a concrete breakwater costing millions of dollars. Three or four 350-foot hulks would be bought, stripped of their super- structure, loaded with rock ballast to their Plimsoll load line, and moored fore and aft to make breakwaters. One of them, meanwhile, might be used as a clubhouse; another would be a supply ship; and a third possibly a marine museum. The ships could be unballasted and towed away, say every other year, to scrape and repaint their bottoms. Despite its novel features, the plan is said to be practical and economical. ged YORK is not the only city with a motor boat problem. Boston, a popular boating center, lacks adequate parking places for boats. A plan suggested by the National Association of Engine and Boat Manufacturers, which would create a series of T-head docks in Pleasure Bay, is interesting because of its method of offsetting the seven-and-a-half-foot rise and fall of the tide. Within the T-shaped dock, boats would moor, not to the dock, but to a floating walk adjoining it that rises and falls while sliding collars hold it to anchoring piles. A hinged stairway leads to the dock. Such a method, of course, is applicable in New York or any other city where tide is a problem. Memphis, where the Mississippi rises thirty- five feet from its low to its high level, has a unique boating center in a floating barge, and larger floating docks are proposed for the future. Chicago has already partly completed one of the finest potential motor boat harbors in the world. An improvement of its water front by a long series of breakwaters and artificial | islands will provide protected lagoons for shel- | tered boat basins. San Francisco, where the newly completed harbor of the St. Francis Yacht Club moors an imposing fleet of boats at its slips and wharves, also plans a municipal “aquatic park” with two huge breakwaters. A modern system of T-head docks not only solved Miami’s motor boat problem, but yielded that city a profit. In nine months this municipal basin paid the city $12,000. That experience is typical of other cities; for in- stance, Detroit, which owned a system of 105 boat wells somewhat similar to the improved ones it now plans, reported a profit for 1927 of more than $9,800. e In other words, caring for the 1,356,000 motor boats in the United States is not only a desirable but also a profitable venture. For- ward looking cities are now providing up-to- date facilities for the spreading sport of motor boating. Rheology, a New Science RHEOLOGY is the science involved when you spread a brushful of paint on the garage door. It is the science of flow, so christened by a group of chemists and physicists who recently gathered at the United States Bureau of Standards in Washington to study the deform- ing and flowing action of paints, oils, lacquers, and other plastic substances. The outcome has been a new word for the dictionary—rheology —and the formation of a society by the same name. HOW TO ATTAIN QUICK SUCCESS |f AVIATION amend eh Cmts atmaey OA bn ore hore = ae AVIATION Aviation needs thousands of men and needs them quickly. Aviation CAN USE YOU if you are properly prepared. We train you at home to enter this new world of opportuni- ties. Costs only 1 cents per day. Most in- teresting, fascinating study the world has ever known. Equip yourself to make more money. Start today by sending for your copy of this interesting, instructive FREE BOOK. THE ART GOEBEL SCHOOL OF FLYING 119 West 12th Kansas City. Mo. it's EASY » » » you LEARN to play tunes at the very start with an easy-playing, sweet-toned Pan-American. Be popular; increase your income. Pan-Americans are the only complete line of nationally adver- tised, moderately b panne factory gu instruments. Send now for details of FREE TRIAL; Easy Payments on any instru- ment for the band or orchestra. - PAN-AMERICAN Sna‘Cese Conant and Case Company 404 Pan-American Buil . Elkhart, Indiana. oy ‘7 C n dothis at homein their\/ h as $100 weekly and even ~y mechanical dentists. . Learn Cartooning At Home—in Your re Time The famous Picture Chart Method of teaching original drawing has opened the door of si ccess for hun- d of beginners. Whether you think you have talent or not, send for sample chart to test your abil- ity, and examples of the work of students earning from $50 to $300 rt week. Please state your age. HE LANDON SCHOO 451 National Bldg. JUST OUT! ; An Institute Booklet on HOUSE HEATING AND VENTILATING Do you know about the many new developments in methods of heating and ventilating? This 32-page booklet will give you full facts regarding the merits of various types of equipment, fue's, etc. and tel!s how to plan wisely for greatest comfort and e:onomy. Price 25 cents Popular Science Institute 383 Fourth Ave., New York, N. Y. Cleveland, W.

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e 930 April, 1930 : POPULAR SCIENCE MONTHLY | 151 At the right is a view of my drafting and fication offices where a large staff of experienced experts is in my constant employ.

— if ; - at — mera ‘. i- is fe if My Offices Just Across Street From U. S. Pat. os Office All drawings and spec- ifications are pfre- pared in my offices. ARAL. ZH a ee ne “ POUT hte ot PEL Be) Meh ene bee = Protect Your Ideas Take the First Step Today—Action Counts nventors If you have a useful, practical, novel idea for any new article or for an 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 proof rests upon the last application filed. Delays of even a few days in filing 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 proceed in the quickest, safest and best ways in preparing an application for a 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. ighest references, But FIRST—clip the coupon ond get my free book. THAT right now, No Charge for Informati —— : On How to Pressed oe Mail this Coupon How The booklet shown here contains valuable information relating to patent procedure that every inventor should have. And with it | will send you my “Record of Invention” form, on which you can sketch your idea and establish its date before a witness. Such evidence may later prove valu- able to you. Simply mail the coupon and I will send you the booklet, and the “Record of Invention” form, together with detailed information on how to proceed and the costs involved. Do this NOW. No need to lose a minute's time. The coupon will bring you complete information entirely

CLARENCE A. O’BRIEN Registered Patent Attorney 88-W Security Savings and Commercial Bank Bldg., Washington, D. C.

without charge or obligation. es. Suite 1106 Woolworth Bldg., ) Clarence A. O’Bri Pert ec rien Please send me your free book, “How to Obtain a Patent,” Registered Patent Attorney “ake ats in Member of Bar of Supreme Court of the United States; fey} Court of Appeals, District of Columbia; Supreme Court, Nn. 4.060.006n0804 50000000 a0 On0b ad beeen ae ~~ District of Columbia; United States Court of Claims. PRACTICE CONFINED EXCLUSIVELY TO PATENTS, TRADEMARES AND COPURIGHTS 8B occtstnccencndccnccnnccncccesscsccoccoesscooesensbn C7 \aerneenmmnsnsnmnmnsummnmmmensnensmmmmmmmmmsy\ <) __ (srs: Wise Prt Pinout Mire Ofer Net Yo 1. Y.

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Sp Ali rato 0 aah ee usa ee een nnn = se AN RE eh ACID OTE Aa NCAR A AOS Ril acta, Wis Bal ile ee we . asieh r I 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 rs open. Alwa * makes good too. I wish I d started studying with the I.C.S. when he did. Are you just wishing for a better job too? Are other men getting the promotions you’d like to have? Are you letting the precious, priceless hours slip by unimproved? You know as well as we do that you’ve got to learn more in order to eorm more. And you know, too, that the best way to learn more is to take up a course with the Interna- tional 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 F Free 5 Booklet _ INTERNATIONAL CORRESPONDENCE SCHOOLS he Universal University’’ on" 7659-F , ten, Penna. Without cost or obligation on my pert, ¥ yd send me a copy of your 48-page booklet, id Why,” and tell me how I can qualify for a opsition, or in the subject, before which I have marked an TECHNICAL AND INDUSTRIAL COURSES Architect Automobile Work Architectural Draftsman () Aviation Engines _!| Building Foreman Plumber and Steam Fitter Conerete Bullder Plumbing Inspector Contractor and Builder Foreman Plumber Structural Draftsman Heating and Ventilation Structural Engineer Sheet-Metal Worker Steam Engineer Marine Engineer Refrigeration Engineer R. R. Positions Highway Engineer Chemistry Pharmacy Coal Mining Engineer Navigation () Assayer Iron and Steel Worker Textile Overseer or Supt. 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Montreal, Canada tl ee “Pick YOUR — GovernmentJob” T'll show you the quickest wey to get on Uncle Sam's payroll. Send for free book—How to re a Government Position. b+ gg for Uncle Sam. Get good pay egular sporences, vacations and sick’ leave with pay, steady ad- t, pension. d for my free book tells sdout all jobs, near home or oe . , raoney, what you need to know and how to Forget “‘job hunting.” IMPORTANT Not! “Railway ostal Clerk exam- ination coming. “Yearly allowances, averages careat "NOW. Write jor my big o-onae book SC IDA . Address Arthur Patterson, Former Ci PATTERSON SCHOOL 164 Wisner Bldg. Rochester, N. Y. POPULAR SCIENCE MONTHLY How to Get Into Gliding (Continued from page 25) 115 members and a waiting list of a hundred more. It is building its own gliders and has more than a thousand dollars in the bank. Not long ago the United States Chamber of Commerce sent a bulletin to the 2,000 cham- bers in the country, urging them to help sup- = the glider movement. Free factory space as been donated by the chamber at Dayton, Ohio, to a club which is building its training plane, and in Florida the Fernandina Glider Club was given help in getting started by the Chamber of Commerce of that city. In other parts of the United States, groups which have shown initiative have received boosts from local civic organizations. One club, a group of high school boys at Sioux City, Iowa, received a fine new glider from an unexpected source. When the Na- tional Air Races at Cleveland, Ohio, took place last August, they brought a homemade ma- chine to compete in the glider contests. T MADE the 1,000-mile trip on an auto trailer. Then, at the end of the first day, a hard landing ‘‘ washed it out.”” Without com- plaint at their hard luck, they prepared for the long trip home. So impressed with their sports- manship was W. J. Scripps, president of Gliders, Inc., that he presented them free of charge with a new training plane. The United States Government recently came to the aid of another club. It granted the Tucson, Arizona, glider club permission to establish a gliding camp on a steep hillside within a Government reservation. Practically all of the leaders of the aircraft industry are behind the movement to foster interest in gliding. Among those who have recently taken an active part are: Charles L. Lawrance, in- ventor of the Wright “Whirlwind” engine; Anthony H. G. Fokker; C. S. “Casey” Jones, president of the Curtiss- W right Flying Service; “Eddie” Rickenbacker, American Ace; Charles F. Kettering, of the General Motors Research Corporation; William B. Mayo, Chief Engineer of the Ford Motor Company; “Eddie” Stin- son; Admiral W. A. Moffett; and Capt. L. M. Woolson, inventor of the Packard Diesel air- craft engine and one of the designers of the famous Liberty motor. N PLANNING a glider club, one of the first things to determine is a favorable spot for practice. Low, rolling hills, free from obstruc- tions, with slopes facing all directions, so flights can be made into the wind no matter from which quarter it blows, are ideal for simple gliding. The hills should be between ten and 150 feet high. For beginners, only gentle slopes should be used. If these ideal conditions are not available, a slope facing the prevailing wind should be chosen. The hillside selected must not be too close to the opposite slope or the latter may shield the‘training hill, “killing” the wind. A valley a quarter of a mile wide in front of the slope is desirable. Along the California coast where Bowlus has done his great flying, a west wind blows almost continually against the high seacoast. Dr. W. Klemperer, who holds the first glider pilot’s license issued in Germany and who is now connected with the Goodyear-Zeppelin Company of Akron, Ohio, believes that a soar- ing flight down the California coast from San Francisco to Los Angeles is entirely possible. W. H. Bowlus declares that a motorless flight from coast to coast, depending entirely upon rising air currents, eventually will be made. POPULAR SCIENCE MonrHLY is now codperat- ing with New York University and the Na- | tional Glider Association in making a survey of | the area around New York City to select the most favorable site for the national glider meet next fall. For ordinary primary (Continued on page 153) APRIL, 1930 fee Wit= Craters inthe MOON! ASTRONOMICAL AND TERRESTRIAL TELESCOPE See yey OR soguvtnaresd oo Sine oom — frietion adjustment f focusing. Adjustable beaches and clamp can be fastened to chair, fence. branch, ete. Finest materials, Will last lifetime. planets, stars your next door neighbors. Moon Craters, Sun Spots, Eclipses, Cor enlarged 30 times. Strange thrills! 5 Days’ Free Trial Rush o. $1.00 now. P,; balance + * 95 plus estes when postman delivers. Keep aan. If not calichtod. Te- urn telescope be refunded. a Roll-O Specialty Co. Dept. D-317 220 E. 3rd St., Cincinnati, 0. f Hours of fun wert ng at mea, bathi * beaution” "Great for tai or trips and voyages, jiete like scineotoes used a observatories. Gerdin wrote, ““Moon scems 1 yards away. Diameter 2 inches. Special MAKE MUCH MONEY Making and Selling Your Own Goods. For- mulas by experts. Ly cme agg 2 Processes, Trade Secrets. All kinds. Alllines. Auto- mobile Specialities. Cleaning and Polishing Compounds. Food Products. Toilet Prep- arations, etc. Send for interesting catalog, special circulars, FREE. C. THAXLY CO., Washington, D. C. _= ~ Patents Trade-Marks EDWARD C. SASNETT Atty. at Law, Registered Patent Atty. Formerly a Principal Examiner, U. S. Patent Office 516 D McGill Bldg. Washington, D.C. PATENTS 23233323 Patents of a e value. pen "Patent t-Sense, Lacey & Lacey St., Wash., D.C, Estab, 1 UNPATENTED IDEAS CAN BE SOLD I tell you how and help you make the sale. Free particulars. (Copyrighted) Write W. T. Greene, 921 Barrister Bidg., Washington, D.C. PATENT ventions Edward Gottlieb ATTORNEY IN PATENT CAUSES 5 Beekman Street, New York Inventions Developed—Representative for Blair Tool and Machine Corp. INVENTORS We have been in business 30 years. If your invention or patent has merit, send details or model, or write for information. Complete facilities. References. gga FISHER MFG. CO., 183-D Enright St. Louis, Mo. PATENTS Trade-marks, Copyrights, Patent Litigation, Handbook with ty somos 100 mechanical movements. Sent free on request. ALBERT E. DIETERICH Formerly member Epouteive Corp. U. 8. Patent Office Registered Patent Lawyer and Solicitor 80 years’ experience 681-A Ouray Bidg. Washington, D. C. — ie Oe et i ee ek ie n= =F 4 4 be ee

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1930 mney will y Co. nati, 0. ‘ion, ical Office D. C. APRIL, 1930 POPULAR SCIENCE MONTHLY 153 ee to Get Into Gliding (Continued from page 152) gliding, in which the machine “coasts downhill on air” a few feet above the ground and does not rise higher than its starting point, as does a light soaring ship, even a small hill will afford thrilling flights. In fact, the first flights are usually made by shockcord launchings from level ground. Only experienced pilots should attempt towed flights behind automobiles. Such places as ledges, quarries and preci- pices are too dangerous for starting spots. The hill selected should have no brush or fences upon it and should be clear at its base. Many beginners have come to grief through sailing farther than they expected and sitting down upon a fence or a clump of bushes. Re- cently, when the members of a New York glider club tried out their new machine, The Blue Bird, Paul Snell, the pilot, made a beau- tiful flight and a fine landing. But the plane skidded into a barbed wire fence and was torn. T PAYS to take time to investigate all pos- sible spots carefully before beginning actual flights. The University of Utah Motorless Aviation Club members, for instance, spent nearly six months looking around and prepar- ing before their first ship, The Papoose, was taken out for trial. It sailed for nearly a mile across a valley and 117 flights were made with only one slight mishap. . Clubs with diverse backgrounds have taken up motorless flying. The A. B. C. Glider Club of Detroit, for example, grew out of the Ameri- can Business Club, an organization of young business men. The Titan Glider Club, of the same city, consists of aeronautical students at the University of Detroit who build and fly gliders as part of their study of the principles of aerodynamics. A Cincinnati, Ohio, club is made up entirely of girls, and a second girls’ organization is now building its own glider at Buffalo, New York. Another unique club, re- cently established at Kansas City, Kansas, is made up entirely of airplane pilots holding transport licenses, the highest issued in Ameri- ca. The youngest glider pilot in the world, probably, is little Danny Crawford, of Cleve- land, Ohio. At four, he recently made a short solo hop under his father’s guidance. LIDING is an all-year-round sport. This should be taken into consideration in planning a club and a practice site. Suitable housing for the machine near the gliding hill should be provided. Planes left in the open deteriorate and, even when tied and weighted down, are in danger of blowing away and being wrecked. At the University of Michigan, members of the glider club fly in zero weather and when heavy snow is falling. Their practice ground is a large conical hill a couple of miles north of Ann Arbor. When the wind is right, they can sail from the top clear across a stretch of marsh and land on another hillside. Last summer “Bud” Dalton, one of the members, got away for a fine flight and soared above the swamp. Trying to reach a knoll beyond, he unconsciously flattened his glide. The plane lost flying speed. The air “went out from under him.” The glider sat so hard the keel sank in the mud up to the pilot’s seat. _ Such accidents, which might prove serious in an airplane carrying explosive fuel, rarely mean more than a bump or a shaking up for the pilot of a light engineless ship. A gliding club which makes careful preparation and acquires standard equipment, enters a com- paratively safe realm of thrilling sport and valuable experience. Next month: ‘‘Riding the Winds.’ How soaring planes cover hundreds of miles and climb thousands of feet into the air. Fascinating facts about sail- planes and the pilots who fly them. Patent Office NZ VICTOR BUILDING Our New Building Nearly Opposite U. S. pecially Erected by Us for Our Own Use Lawyers and Draftsmen. ‘ J _in regard to Patents, Trade-marks or Copyrights without charge. FOR THE PROTECTION OUR OFFER: OF YOUR INVENTION YOUR FIRST STEP—The inventor should write for our blank form “RECORD OF INVENTION.” Before disclosing your invention, a sketch and description should be made on our “Record of Invention Blank,” signed, witnessed, then re- turned to us and we will place it in our fireproof secret files. We will also give our opinion as to whether the invention comes within the Patent Office definition of a patentable in- vention. This “Record of Invention” will serve as “proof of conception” until the case can be filed in the Patent Office. There is no charge or obligation for this service. Write for Our Five Books Mailed Free to Inventors Our Illustrated Guide Book HOW TO OBTAIN A PATENT Contains full instructions regarding U. S. Patents. Our Methods, Terms, and 100 Mechanical Movements illustrated and described. OUR TRADE-MARK BOOK Shows value and necessity of Trade-Mark Protection. Informa- tion regarding TRADE-MARKS AND UNFAIR COMPETI- TION IN TRADE. OUR FOREIGN BOOK We have Direct Agencies in Foreign Countrigs, and secure Foreign Patents in shortest time and at lowest cost. PROGRESS OF INVENTION Description of World’s Most Pressing Problems by Leading Scientists and INVENTORS. DELAYS ARE DANGEROUS IN PATENT MATTERS TO AVOID DELAY: YOU SHOULD HAVE YOUR CASE MADE SPECIAL IN OUR OFFICE to save correspondence, secure protection and early filing date in Patent Office. You should send us a model, sketch or photograph with a description of your invention together with $25.00 on account. We will make an examination of the U. S. Patent Office records and if it is patentable we will prepare the official drawings immediately and forward them for approval. If the invention is not patentable we will return the fee less the cost of the examination. PAYMENT OF FEES IN INSTALLMENTS It is not necessary that the total cost of a patent be paid in one payment. We permit our clients to pay for their applications in three installments as the preparation of the application progresses in our office. ALL COMMUNICATIONS AND DATA STRICTLY SE- CRET and CONFIDENTIAL. INTERFERENCE and IN- FRINGEMENT SUITS PROSECUTED. Our Large, Compre- hensive Organization has been established for 30 years and offers Prompt, Efficient and Personal Service by experienced Patent We shall be glad to have you consult us or to answer any questions We Assist our Clients to Sell Their Patents Highest References—Prompt Service—Reasonable Terms WRITE TODAY FREE COUPON VICTOR J. EVANS & CoO. Registered Patent Attorneys: Established 1898 MAIN OFFICES: 690 Ninth St., Washington, D. C. BRANCH OFFICES: 1007 Woolworth Bldg., New York City; 1640-42 Conway Bldg., Chicago, Ill.; 514 Empire Bidg., Pittsburgh, Pa.; 828 Fidelity Phila. Trust Bldg., Phil 1010 Hobart Bldg., San Francisco, Calif. Gentlemen: Please send me FREE OF CHARGE your books as described above. adelphia, Pa.;

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a ee ee ot NO ce ek A Se hb es Jo pS suememmcere as: er roe eee 9 eK eee a oe BE an ARTIST Earn a Fat income HAT would you give to be thoroughly trained in Mod- ern Art on which magazines, news- papers and publishers are spending _ millions every year? Many Federal Students who already have this training are earning from $2500 to $6000 a year—some even more. More than fifty famous artists making big incomes themselves have contributed exclusive lessons and drawings to the Federal Course in Illustrating. Through these lessons you may get the benefit of their long experience in Illustrat- ing, Cartooning, Lettering, Poster Designing, and Window Card Illus- trating. Careful training through the Federal Course teaches you to turn simple lines into dollars. You learn at Keune i in spare time. Earn while you learn if you wish. Through their professional success hundreds of Federal Students have already proved the value of this home study art instruction. TEST YOUR TALENT—FREE Fill out the coupon below and get the Free Book “A Road to Bigger Things.”? You will also re- ceive our Free Vocational Art Test to measure your ability. When you fill this out and return to us our instructors will go over it and give you a frank opinion as to your ability. Mail the Coupon POPULAR SCIENCE MONTHLY Your Car Is Pigeon-Toed (Continued from page 74) still more important, the wheels may be out of balance. And when they are, you can’t al- ways see it. They seem to run just like any other wheels.” “How do you make a test then?” Topham asked. “You can test for both troubles at the same time,” the garage man said. “Jack up one front wheel. Give it a spin and see if it runs true. Then let the wheel slow down. If it always stops at some definite point, you can be sure it’s out of balance. The tires turned out these days are marked so that they should be put on in a certain way. They are purposely made out of balance, just enough to compensate for the weight of the valve stem. If you get ’em on right the wheel will balance. If you get ’em on wrong way round, the unbalance of the tire adds to the weight of the valve stem and then you’re in for grief. Even if the car doesn’t shimmy every time you hit a bump, it will have a tendency to wobble.” “But suppose that the wheel is out of bal- ance even with the tire correctly installed?” objected Topham. HAT happens sometimes,” Gus conceded. “The rim may be slightly out of balance or perhaps one spoke is just a little too heavy. In a case like that, take a little sheet lead and fasten it to the rim at the point that stops at the top. You should add just enough lead so that the wheel will stop at any point and will have no tendency to roll back and forth.” “And how can you fix the camber if that isn’t right?” Topham asked. “Usually the camber is all right unless the axle is bent. If the caster is wrong that’s easily fixed by dropping the axle away from the spring and putting an iron wedge between the spring and the axle, with the thin edge of the ' wedge pointed forward.” “Well,” said Topham, “if you have the wheels lined up and the job on the rear fixed, I think I'll run along. My neighbor has been kicking about his car shimmying. I’m going to hand him some of the dope about caster and camber and maybe he can fix it.” “He can if he knows what he is about,” said Gus. “Better tell him, though, that the first | thing to do is to find out if the wheels wobble | and whether they’re in balance or not. And, if he isn’t a pretty good mechanic, you’d better tell him to bring the car down here.” Skull with Apelike Jaw May Be That of a Man Ir THE skull with an apelike jaw, found re- cently near Peking by Dr. Davidson Black, of the Peking Union Medical College, should prove to be that of a human being, evolution- ists will have established a very valuable link in their theory of man’s ascent from the monkey. “If the report is correct,” says Dr. J. W. Gidley, of the Smithsonian Institution, “the find is of great importance. It demonstrates that in the early stages of human development there was a type of man with a human cra- nium and a receding chin similar to that of the modern ape. Parts of such a skull, together with a jaw like that of a chimpanzee, were found at Piltdown, England, in 1911, and there has been a controversy ever since as to whether skull and jaw belonged to one and the same individual.” A close comparison of the Piltdown skull with that of the recent discovery in China might establish definite facts about the features of our prehistoric ancestors. APRIL, 1930 WHAT EWE Rw READ A BOOK A MONTH j PAY $1.50 A MONTH Start progress today! Subscribe to ‘» Audels monthly book service. One subject mastered may be worth 10 times the value of the whole set to you, Keep up to date. Send coupon today and start this valuablc electric course, Satisfaction Guarantced. just Published! Exact Information from AtoZ. Audel’s NEW Electric Library— for home study and ready reference. Late formation from foundations of ful Practice to newest. a, 25 Al2 pocket-size—7 books EASYto learn; a step-by-step progressive course, written - plain language, w questions an a n- swers, fully illustrated. EASY to read; pocket- size, fexibiy bound in red and gold. A handsome series AUDELS NEW ELECT RIC LIBRARY ves inside information based on ar . poowens on thousands of pn ee ———— in- cluding: ~ — MAILTHIS COUPON TODAY __ THEO. AUDEL & CO., 65 W. 23d St., New York, N.¥, Please enter my subscription te ““AUDELS NEW E IC LIBRARY,” 12 books. Mail one book a month and as received I wili mail you $1.50 promptly. Name poner Address Occupation Emnloyed by PATENTS BOOKLET FREE none § are PROMPTNESS ASSURED Send drawing or meee ® for MA. d., and advi WATSON E. COLEMAN, Patent Lawyer 724 Ninth Street ‘Washington, D.C : —— New Worlds to Conquer ~ | LE _—_ Bg always has new worlds to ily seekii further Betterment = L rott turn of og he ma. ine that every eae youth thoald 2157 B St., N. 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., 1930 4 TH H ibe to One g Pade 2S tT Ff ead NY, YELS Mail mail City, Mo. ft (looks forever) Aprit, 1930 — How Air Camera Men Map Unseen Places (Continued from page 43) a ground survey that would require years to complete. So the county called for bids to map the country from the air, and the task was assigned to us. Here was a section of land the entire width of Long Island and some twenty miles long. For economy we decided to make the pictures ona scale of 600 feet to the inch, meaning that each seven-by-nine-inch picture would take in nearly a square mile of territory. A moment’s figuring, knowing the scope of the standard camera, showed that to obtain this scale the plane would fly at an altitude of 7,200 feet. The higher the airplane flies, the smaller the scale and the more territory is included in each picture. E ASSEMBLED the four Government “ quadrangle’ maps that showed Nassau County, and drew flight lines across them. These were the lines along which the pilot would steer the plane, by compass for directionand byaltim- eter for height, while the photographer took pictures. The lines were purposely drawn so close together so that the pictures would over- lap about sixty percent. This is because a directly vertical. picture is the only strictly accurate representation of any but a perfectly flat surface. Thus we were able to use only the accurate center part of each picture. The camera used was the same one employed for all our mapping—a standard make of aerial camera using roll film and taking 100 pictures, each seven by nine inches, to the roll. The long “focal length,” or distance of lens from film in such a camera, permits larger pictures of distant objects, just as a telescope magnifies them more than a short-barreled field glass. The lens, in its projecting snoutlike barrel, is a large one to let enough light through for high-speed photography. Of course there are no “time exposures” in air mapping; the plane’s movement makes rapid snapshots obligatory. EFORE westarted taking pictures, the pilot would fly along one of the lines timing him- self. Knowing the time it took and the number of pictures to be made, the photographer can reckon the intervals in seconds at which to click his camera, allowing a few pictures extra for overlap. So, on any fine day, our planes were in the air shooting pictures over Long Island. Meanwhile a ground survey party started at United States Coast and Geodetic survey marks on the south shore and tri- angulated, or measured the distances, across the island to the north shore. The object was to obtain a “control” chart locating several landmarks exactly as a guide for piecing to- gether the photographs. Contrary to popular impression, air mapping does not dispense entirely with ground surveying. They work together. But the simple survey needed for an air map, to establish a few reference points, is not to be confused with the elaborate and costly ground survey to locate rivers, roads, and buildings when the entire map is to be done from the ground. The camera takes in every detail to the smallest tree, more faith- fully than the best surveyor. When the photographs for the Nassau map had been taken, they were hurried to our laboratory and developed in a totally dark toom. The films are so sensitive to all kinds of light that even the conventional photographic red lantern used in developing ordinary would ruin them. Prints were then made from film negatives on paper. A map assembled from the first photographs would be of enormous size. One such map was actually made—a huge mosaic twenty- eight by twenty-one feet. But for convenience in handling, the (Continued on page 156) POPULAR SCIENCE MONTHLY 155 DON’T BE BURIED ALIVE! Be An $8000 A Year Man $20 to $25 a DAY. 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Gain quick success in this most fascinating and profitable field. Learn at National in the center of tremendous electrical projects costing more than $100,000,000.00 Practical, i ive taniaiag by Meslonsls | , hod in 6 to 9 months. All technical pool scarey School endorsed imelectrical industry. You learn all branches of electricity; radio. Million dollar institution; all modern uipment and training facilities. Life olaeiie, No age limit. Free employ. Jp REE ment service. Over 20,000 successful graduates. 25th year. Big, illustrated BOOK 84-page catalog sent FREE. Write today. Dent 307-ED. 4006 So. Figueroa, Los Angeles, Calif. $165,000 REWARD for anIDEA That sum was paid to the inventor of “Kiddie Kars.” Here is a remarkable book which tells you what inventions are NEEDED in every field. Don't waste your ideas. Send today for 1000 NEEDED INVENTIONS Prepared Ld Raymond F. Yates, famous inventor, for- mer manag’ knows what manufacturers want. edition contains valuable chapters on Aviation and Television. This book may start you toward a fortune. Send no money. Just write a postcard. Pay mail man only $1.50 j -—— Postage when book arrives. Money back after ten G cash with order.) Bureau of Inventive Science 224 Wisner Blidg., ng editor of Popular Science Monthly, who New, revis 1930 Limited offer. Write now. ays, if desired. (Outside U. 8S. $1.70 et started in right direction. Rochester, N. Y. TO THE MAN WITH AN IDEA PATENTS Procured. Trade-Marks Registered. —A comprehensive, experienced, ep service for the protection and development of your ideas. Preliminary advice gladly furnish without charge. Booklet of information and form for disclosing idea free on .request. IRVING L. McCATHRAN PATENT LAWYER Formerly with and successor to ichard B. Owen on, D.C, 705 International Bidg.; Washin 41-D, Park Row, New York City TRADE =MARKS REGISTERED TRADE-MARKS DO NOT LOSE YOUR RIGHTS TO PATENT PROTECTION Before disclosing your invention to anyone send for blank form ‘“Evi- DENCE OF Conception” to be signed and witnessed. LANCASTER, ALLWINE & ROMMEL Registered Patent Attorneys 274 Ouray Bidg., Washington, D.C. Originators of forms ‘‘Evidence of Conception” fore ATEN TS ECURE TRADE-MARKS REGISTERED High-class professional service for Inventors and Trade-Mark Users is necessary for PROPER PROTECTION. We Offer you our facilities on Reasonable Terms. If i us a model or sketch and description and we will give you our OPINION whether comes within the provisions of the Patent Laws. Our book, “ ou have an invention send our invention HOW TO GET YOUR PATENT" and Record of Invention Certificate sent on request. DELAYS are DANGEROUS in Patent Matters. WE ASSIST OUR CLIENTS TO SELL THEIR PATENTS TERMS REASONABLE IIIS 555-4.0 tence. essen % Augie ae Se ee eee BEST REFERENCES -nnocmananmanaencn CIEE TRAY nan acanararscn mansoni RANDOLPH & COMPANY, Patent Attorneys ’ ' Dept. 130 Washington, D. C. : i TETTPETETITL TTL 1 '

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How Air Camera Men Map Unseen Places (Continued from page 1565) map had to be reduced in size. Therefore, with the ground survey as a basis, individual pictures were assembled on fourteen mounts of wall board, each eight feet high and seven feet wide. We took care to correct any distortion caused by the earth’s curvature, which made the top of the map about three or four inches shorter than the bottom. Then the boards were set up in front of a copying camera and each board rephotographed by sections, on a reduced scale, upon glass plates twenty by twenty-four inches in size. Prints from these large negatives were made in an ingenious machine that assures sharpness and clear detail. A vacuum pump sucks out | the air between negative and paper and squeezes them together tighter than a thumb caught in a door jamb. Pasted up, the prints were used to make maps of handy dimensions— twelve by eight and a half feet, and smaller; in a variety of sizes. N ADDITION, certain sections of the map, of particular interest, were enlarged to as large a scale as one hundred feet to the inch. This was done in a special enlarging camera built to our specifications, probably the only one of its kind in the world. It handles twenty-by- twenty-four-inch glass negatives. Powerful mercury vapor lamps behind the wall in an adjoining room supply the light used to im- print the enlarged image upon the sensitive enlarging paper. The camera is focused by a precisely gradu- ated scale, charted for any degree of enlarge- ment or reduction, instead of by eye. It is merely necessary to set the camera and fire away. As an indication of the standard of ac- curacy we maintain, we found it necessary to avoid one well-known make of enlarging paper. It would be perfectly satisfactory for ordi- nary photographic work, but we have dis- covered that in drying it shrank five percent more in one direction than it did in the other. That would spoil the air map because dis- tances measured upon it would no longer be correct. The completed tax map of Nassau County is a fair example of the benefits of air mapping. It saved the county about $100,000 in the first cost of mapping; a ground survey would have cost approximately $125,000, while the airplane did it for a fifth of the cost. Four or five departments so far have had occasion to use it, and through this, in a year and a half, the map saved Nassau County $200,000 more. One unexpected use is in mosquito control. Bogs and marshes are clearly revealed on the map, and lines for drainage ditches can be laid out directly upon it. Although the practice of making air maps has been customary for several years, we are,at present just com- mencing to find out what can be done with them. Moth’s Birth Rings Bell Tue birth ofa royal prince or princess is usually hailed with the pealing of chimes, but in the new Slough Entomological Laboratory in London, England, a bell rings every time a moth is born. The entomologists in charge of the laboratory find it necessary to keep accu- rate records of their study specimens, includ- ing the exact time of their birth. To make this possible, they have constructed a device con- sisting of a small platform suspended from a spring. The pupa from which the moth is tc emerge is placed on this platform. When the insect is born, the spring flies up and this action results in the ringing of a bell.

APRIL, 1930

The greatest manual of wiring information yet devised for the practical men. A Handbook for Electricians Based on the 1930 National Elec- trical Code. By Harold P. Strand Master Electrician This New Manual—the biggest, most com- prehensive, thorough and practical operating guide of its kind ever prepared—answers the everyday questions that arise in the work ef wiremen, electricians, and students of practical electricity. It presents a great collection of brand new diagrams and pictures that tell the story better than words. It- gives in detail the wiring operations commonly encountered by the average electrical contractor, all in accordance with the rulings of the 1930 National Electrical Code. In this one handy volume is condensed as much practical, timesaving information as you would expect to find in a complete set of reference books. It is crammed with pointers on almost every phase of electrical work as practiced by the electrician of today. Theory is dispensed with as far as possible to make the information simple and easy to understand. The author has spent seventeen years in the electrical business, starting as an apprentice. Still actively engaged in the work, he conducts his own business of electrical contracting and consulting. 22 Practical Sections Cover In Great Detail - - Armored Cable—Rigid Conduit—Metal Mold- ing—Fixtures—W iring for Electric Appli- ances—Wiring Gar- 4 ae Station iring—Sign Wiring —Transformers—El- evators—Special Wir- ing Conditions—Switch— boards and Panels— —Wires and Cords— Direct Current Motors and Generators—Alter- nating Current Motors —Exhaust Ventilatin: Fans—Estimating an Laying Out—The Repair Man—Radio—Bells, Tel- ephones, Annunciators— General Hints for Wire- men—Tables and For- mulas.

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, 1930 yet for lec- ode 32 Ee ee During the past few months we have placed HUN DREDS of our graduates and also students when only half through the course—in well-paid Electrical Fo gee These men are now on the igh road to a real future in the world’s greatest business —some in power plants—some in Electrical factories —others in the business or drafting or selling or radio end. Go After the Big Money j The big Electrical Utility magnates tis factory job have just laid down a TWO-BILLION tonttruction and DO R program of new projects mainten nce work. before President Hoover. Remember, W.B. McClellan, that’sin addition to the billions already Mason City, lowa invested and the millions of men already employed in Electricity. Just think—how light, power, rail- roads, radio, telephone, telegraph, all manufacturing, automatic devices, home appliances — now depend on Electricity. That’s a wonderful line to get into—because it has no “hard times” or unemployment. And now it’s easy to break into Elec- tricity. In your spare time, right at home, +, can now quickly master WIRING 1O0TORS, GENERATORS, POWE PLANT EQUIPMENT and other fasci- nating branches of the work—and almost before you realize it, we'll be recommend- ing you for your first Electrical position. ‘= WHO ELSE *: Wants A Good Electrical Job? Glen Sk ae Leighton, lowa The letters shown at the left are just typical of HUNDREDS we'd like to show you. We want to tell you more about the wonderful chances a for you in Electricity — our fastest ing industry. Mail coupon for an interesting proposition we are making right now to ambitious men. American School 2e7'sei® brexs! Ave. SBC we Dm ee ee ee ee ae ee Re Se AMERICAN SCHOOL, Dat 43 Drexel Ave. and 58th St., cago, Ill, Please d ithout 1 Electri Setin and tell me about ny ped Pena mene ay and ———- 1 Gentlemen: Thanks to the consistent effort of the Ame School I nave ound an entire job _ we “I have accepted employment wi the lowa Railway it Corpo- service in line marked & below. D ELECTRICAL ENGINEERING Barchitectwre = i Rccgurtin ew ecerg Rone ret Steel i enee Superintendent O Auto Engineering O igh School in 2 years An educational and entertaining instrument that en- ables all-to see and know life invisible to the naked eye. Thrills and fun galore! See tiny bugs grow to proportions of great elephants. See plant and mineral life reveal amazing wonders in form and color. Made just like microscopes used by physicians, scientists, etc. Now only $3.98. Could easily sell for $10 and $20 more. Ad- justable lens of 240 power! Send only $1.00. Pay I ($2.98 plus postage) when postman delivers. If not satis- fied, return in § daysand your moncy will be refunded. IDEAL FOR STUDENTS! Dealers and Teachers A wonderful help * Write for Our in studying science, Proposition ! botany, ete. Never bef has such a woadsrtal instrument been offered at such an amazingly low price of $3. R. B. SPECIALTY COMPANY 220 E. 3rd St., Dept. D-350 Cincinnati, Ohio POPULAR SCIENCE MONTHLY Explore Weird Island of the Dead (Continued from page 23) almost every natural cave was used for the disposal of corpses. How many people once inhabited the island? This question, too, is shrouded in mystery. According to native tradition, it was populat- ed by many clans, almost perpetually at war with eachother. The immense amount of labor age by the image makers and tomb uilders, provided it was not stretched over centuries, indicates that the island may once have teemed with people. On the other hand, the limited area of tillable soil precludes the possibility of a dense population at any one time and gives weight to the “sunken con- tinent”’ theory. LTHOUGH historical records conflict, there is little doubt that in more recent times the population has been at least ten times as numerous as it is now. Admiral Jacob Roggeveen, of the Dutch navy, who discovered the island on Easter Sunday, April 7, 1722—a circumstance to which it owes its name—wrote that “several thousand” natives surrounded him and his men upon landing. According to a certain Behrens, a member of the expedition, who may not have disembarked but merely viewed the giant statues from shipboard, the male inhab- itants were “‘children of Goliath,” twelve feet tall. The women, he wrote, were “only” ten feet tall. Measurements of skeletons in the oldest tombs have shown that the tallest Easter Islander was a little short of six feet. Fifty-two years after Roggeveen’s discov- ery, Captain James Cook, famous English mariner, placed the population at only 600 or 700. Later explorers estimated it at 1,500, 2,000, and even 20,000. Whatever the actual number, it was greatly reduced in 1863, when Peruvian slave-raiders kidnapped the majority of able-bodied men and carried them off to work in the guano deposits of the Chincha Islands and on plantations in Peru. Only a small group was later freed, and of these all but two died of smallpox on the homeward trip. The suryivors infected most of the women, children, and old men left on the island, which was almost decimated as a result. But when the last party to explore it, that headed by Dr. and Mrs. Scoresby Rout- ledge, British scientists, reached it in March, 1914, they found the population had again increased to a little over 200. The early Easter Islanders who built the formidable burial platforms, called “ahu” by the natives, must have had considerable engineering skill. The giant tombs consist of a loag stone wall, running parallel with the ocean. The stones, some of which are six feet long, are fitted together without cement. On the land side they are buttressed with a slope of masonry, cunningly constructed to haul the huge images to the top. The burial vaults were underneath the slope. The ahu usually carried from six to twelve images. The largest served as a pedestal for fifteen of the enormous busts. HERE are between 600 and 700 of the fan- tastic stone figures on the island; in the quarry alone there are ninety-three, forty of which are finished. The tallest are more than thirty feet; one, an unfinished monster, meas- ures seventy feet. Its weight is estimated at 250 tons—the heaviest whale ever caught weighed 147 tons. A few are only six feet long, and there are even smaller ones. Those on the ahu were from twelve to twenty feet high and were topped by a curious crown or hat, hewn out of red volcanic rock obtained in a small crater near Cooks Bay. The brim of this head- piece projected over the eyes of the figure. To this day, the Easter Islanders sport straw “toppers” of the same (Continued on page 158) 157 TEST YOUR AkI ABILITY ERE is your op- portunity to find out how much talent you have. Our simple, scientific Questionnaire tests your na- tural sense of design, propor- tion, color, perspective, etc. It may show you the way to a bigger future—a real career. Federal Students Are Successful Many Federal School stu- dents are making $2,000, $4,000, $5,000 and $6,000 yearly. The Federal School is recognized everywhere by emplogers of artists and by buyers of art work. Big prices are paid for drawings. Learn Commercial Art at Home If you like to draw, an almost sure indication of talent, the Federal Course will quickly develop your ability to earn money. Some students earn more than the cost of the course while studying. Many nationally known artists have contributed exclusive, illustrated lessons to the Federal Course. No previous training is needed. You will receive personal, individual criticism on your work. Send TODAY for Questionnaire! Just fill out and mail the coupon, stating your age and occupation. There is no cost or obligation to you. i 1 ] 1 : ! 1368 Federal Schools Bldg., Minneapolis, Minn. Send me your analysis questionnaire without 4 ' cost or obligation. { oP MOMMIDY. «sk o:s5:3 2a 0s 2 OO ae Ree ee ee t ! Present 4 aes ay Peery Occapation.......... t ‘ CEE.» n vctinnite «kee thd +e bcs keen : 1 ‘ {

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eT ee ee ee ee TM soe sr ee ee |

158 POPULAR SCIENCE MONTHLY 11 Thrilling Dee Wite Models

Note to Dealers ie @ group of responsible mer- chants, presenting a quality mt in @ worthy way. Some is still I anid Mio ch be aie a - pw -to- le ¢ that will bring you and your family and pom ee pleasures this summer. , , . The Dee Wite dealer organisation Spend leisure

very one a dry, safe, roomy and friends summer hours on the water away from the heat, noise and dirt of the city. Entertain in a distinctive and delightful way. Commute back and forth to the city. Speed away to distant fishing haunts, picnic spots, bathing beaches. Go to your Dee Wite dealer today and i values, or mail coupon for fully descriptive catalog. t these

1 boating r DWIGHT LUMBER COMPANY

full in Dept. 444 Boat Division Detroit, Michigan MAIL Dwight Lumber Co., Dept.144 Boat Division, Detroit, Mich. THIS Please mail Dee Wite Catalog and name of nearest dealer. COUPON Name Now Address

I'll hand it to you for doing your darnedest to get your hands clean with ordinary soap. But, man, you can’t do it with ordinary soap. I’ve tried, and I know. The only soap I’ve found which can do it is Lava Soap. Ask Jim, or Ed or Bill—fellows who have work like yours— they know Lava, too. They’ll tell you it’s the best hancl-friend they’ve got. It gets the grime and grease, but leaves the skin behind. Gets work-stained hands clean in 58 seconds, be- cause it’s made from pure vegetable oils and pulverized Italian pumice that’s almost as as flour. Makes a rich, creamy lather in the hardest water. Sane the fas Soop Man Lava costs adime (or 6c for the medium size cake) at any drug or grocery store. But if you want totry it at our expense, mail this cou- pon. Procter & Gamble, Dept. X-430 Cincinnati, Ohio George: I want a free sample cake of your Lava Soap.

One handy Counter to have with you :—the VEEDER-ROOT Hand Tal- ly. Counts one for each press of thumb lever. Counts anything any- where—from people at an amuse- ment park to poles on a power line. Here’s just the Counter for stockroom use, . to record the number of bars or other units of stock on hand, of different sizes or specifications. Or the number of packages, boxes or bales in inventory. Or for count- ing parts or pieces in assembling operations, as an aid to time and motion studies. Price, $5.00. Circular sent first if you say. Noodou- ROO ]NCORPORATED HARTFORD, CONN. is ~ OFFICES IN PRINCIPAL CITIES: WRITE OR PHONE

APRIL, 1930 >

Explore Weird Island of the Dead (Continued from page 157) general shape, and worn in a similar fashion, All of the statues are half-length figures, with the hands almost meeting in front, at the base, In every case the head is long, with a long, low- bridged nose, somewhat pouting lips, and peculiar ears cut in the form of ropes. The expression is stoical, solemn, severe. Not a single one of the ahu images is now standing in its original place, and most of them are damaged. [Fairly reliable story-tellers among the oldest men ascribe this condition to comparatively recent clan warfare, in which the busts were hauled down with ropes. UT how did the ancient workers get themout |- of the quarry, up hill and down dale, and transport them to the platforms on the coast? The natives explain it in their one favorite word, “‘mana”—magic. Possibly, a system of chocks and wedges was used to lift them, a slide made to launch them from the crater to level ground, and the rest of the hauling done with hempen ropes. One visitor to the island, who found large circular holes drilled deep in the rock of the image mountain, thought that the statues may have been moved by an ingenious species of prehistoric aerial trolley. High poles, he fancied, may have been wedged in the open- ings, and from the top of the beams to the plain below strong thick ropes may have been stretched down which both men and cargo passed, yams being used for lubrication. Un- fortunately for this theory, there never has been, so far as anyone knows, sufficient lumber on the island to make a hatrack, not to men- tion trolley poles. But aside from the ahu and the images, there are other. mysterious relics on this island of the dead. At Orongo, in the south- west, stands a long-deserted village of nearly 100 stone houses, built against a terrace of rock. The walls are often five feet thick, but the tiny doors are only twenty inches high and nineteen inches wide. Paintings of birds, animals, faces, and geometric figures in red, black, and white decorate the walls. Near the huts, some of the rocks are carved into curious shapes, representing human heads, turtles, birds, fish, and weird creatures never seen on land or sea. Some sixty years ago, the mystery .was fur- ther deepened by the finding of seven ancient wooden tablets and a number of small wooden household gods. It is assumed they were made of driftwood. The tablets are covered with hieroglyphics, a picture writing in which human figures, beasts, and birds play prominent parts. Paymaster William J. Thomson, who visited the island in 1888 aboard the U. S. S. Mohican and who made a study of the place for the Smithsonian Institution, deciphered parts of two of the tablets with the aid of an old chief. NE of the translations describes a country intersected by paved roads, and indicates, by references to severely cold weather, that Easter Island, now in the subtropics, may at one time have undergone great climatic The writing on the other tablet is of a purely religious nature. Reminiscent of the psalms of | David, it appears to be a hymn of praise, poetic in quality and monotheistic in theme, to a supreme god, who is called “ the Great King.” Were these tablets inscribed by the same people who carved the huge images and built the massive tombs? And did they, or others, ° cut the wooden idols and erect the strange stone houses? These and the other Easter Island enigmas may be solved after the Johnson expedition explores this mysterious little patch of dry

land in the South Pacific. ae

April

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» 1930 1 and , and some apes, ; fur- cient oden made with man inent who place nered of an intry ates, ary at ange. urely ns of ApRIL, 1930 Fortunes That Farmers | Throw Away (Continued from page 21) ilar fruits formerly were thrown away. Now they are heated in retorts to yield a valuable grade of charcoal like that used in war-time gas masks, as well as methanol, acetic and other acids, and still other chemical materials. From seeds removed from raisins or recovered in the manufacture of grape juice “sweet oil” is made. Apple cores and skins have become a com- mercial source of pectin, the colloidal material which makes jellies “jell.” Peanut and pecan shells are under further study by growers. The small, damaged, or poor-looking fruits from the California orange or lemon orchards are perfectly wholesome but undesirable for the general market. Aided by a local labora- tory -of the United States Department of Agri- culture, the citrus growers have developed manufacturing methods and markets for orange from these fruits, for the same jelly-making pectin made from apples, and for other by- products. The ultimate pulp, from which all Juice, sugar, oil, and pectin have been extract- ed, is useful for stock food. HESE are examples of how chemistry has aided well-organized, closely-centered kinds of agriculture. Others are possible. As- paragus canning, for example, still has a large unused by-product of the lower ends of as- paragus stalks, waiting for some chemist to find useful products in them. Grape skins are still not so useful as their chemical content of acids, vegetable dyes, and vitamines may some day make them. The potato industry, at least where these vegetables are sliced, canned, or made into other potato products, has a poten- tially useful by-product of skins. Present public interest in vitamines and min- eral salts for human diets probably provides opportunity of utilizing wasted parts of spin- ach plants, onion tops, cull carrots, extra leaves from the heads of lettuce and cabbage, cull cucumbers, and other green-leaf by-prod- ucts of the vegetable industry as chemical sources of these necessary food materials; to be treated chemically as vitamines are now extracted from yeast or perhaps merely to be sold in dried and powdered form as useful sub- stitutes for the vegetables themselves when these are scarce. Cull tomatoes have already been used in this way to yield a drinkable juice containing vitamines and mineral salts. UT these are organized industries. How can chemistry be applied to diffuse, ab- solutely unorganized agriculture? Professor Sweeney and his associates have an answer. What they foresee as an outcome of the present cornstalk company is a net- work of small factories scattered over the corn belt states, like creameries in a country devot- ed to dairying. To these factories farmers will bring their cornstalks. Manufacturing and the preparation of chemical products will be done by the factory, and the farmer will receive a cash price for his cornstalks in addition to whatever he now receives for his corn. This plan cannot but appeal to everyone who knows agricultural America for the rea- son that it requires a minimum of codperation from the farmers themselves,who are notorious- ly difficult to organize or to interest in codéper- ative plans. Individual farmers need not sell their cornstalks to the factories unless they like. For a long time there will be plenty of cornstalks to go around even if a fair propor- | tion of farmers hold aloof. And gradually the | farm population not only will draw able, co- operative recruits back from the cities by the | universal magnet of more money, but also will learn that’ codperation pays. This is why the million-dollar bet on cornstalks seems a prom- ising event for the American farm. and lemon juices and oils, for citric acid made | POPULAR SCIENCE MONTHLY Att or action... Graflex i is the most versa- makes artistic sais es ateur and professional alike. The CAMERA For More Interesting Pictures 159 PS Re clits SOL es

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160 POPULAR SCIENCE MONTHLY Apri, 19 ‘ t Has your favorite service Station man seen this demonstration ? p AN the right is the demonstration machine which engineers from the Ethy] Gasoline Corporation take from place to place to prove how Ethyl “knocks out that ‘knock’” and de- velops an engine’s maximum power. In those two vials at the right of the cylinder is the fuel. One contains ordinary gasoline, the other Ethyl! Gasoline. By turning the valve between them, ordi- nary gasoline flows into the combustion chamber. The engine “knocks”; its speed de- creases; the power begins to drop. Then the valve is turned in the opposite direction to feed Ethyl into the chamber. The engine quiets swiftly. “Knock” goes out. R. P.M’s (engine revolutions per minute) in- crease. And the engine delivers the power of which it is capable. That’s why thousands of service station men advise you to use Ethy] in your own car. They know that amy car performs better with Ethyl Gasoline in its tank. ae Ethyl Gasoline Corporation, New York City ans ne OT RTZD Fitted into the rear of this car is the “knock” demonstration machine. (Above at right) The machine ready for action. y 7 Wherever you drive—whatever the oil com- + 4 a pany’s name or brand associated withit—any O00 play ETHVE gual — pump bearing the Ethyl emblem represents icasoune P'™ riuin “C “casoune} quality gasoline of high anti-knock rating, ETHYL GASOLIN © £. G. c. 1930 The active ingredient now used in Ethyl fluid is tetraethy! lead. R. R DONNELLEY & SONS CO., CHICAGO