Popular Science Monthly 1930-03: Vol 116 Iss 3

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'M ONTH LY Poivided: 1872 a." March 1940 | 25 cents EER 4- \y30 Thousands Take up Gliding, | ~You Can Learn in] Hour | Hypnotism—Fake or Real? TheMenWhcWill Award Our. alt Prize Modern Tires ‘yaad to Please a Boy America Gets World's Biggest Planes With the Tugs that Dock the wind Liners ‘Was Your Dog Once sini! KiOithinrd Motorboat | That You = Build New Ways of Controlling | | the aed Grid Tube My Airship Adventures | by the Commander of & the Los Angeles’ Sa i” { {

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at Sp BS en on = se HESE MEN KNOW TOOLS HE carpenter, the builder, the industrial worker, the expert woodsman: These men know tools. They know that with all their skill, they cannot do fine work «vith cheap ones. Let their ripe experience and judgment guide your choice. Grip a Plumb Hammer and feel the differ- ence in the balance; pull the slimmest headless brad with those nipper claws. You will have more confi- dence .. . you'll do better work with a tool like that. Try the Plumb Hatchet; it is balanced to control your blows. Sink it deep or slice a shaving; that keen edge goes where you aim it. Or the Ball Pein—favorite of machinists; or the Plumb Chopping Axe—selected by expert woodsmen. Notice how many experts use Plumb—with the Red Handle and Black Head. Because they are easier to work with, turn out a better job, give longer life .. . And the handles are always tight! Plumb’s invention —the screw wedge—instantly takes up any shrink- age in the handle, just by a turn of the screw. Your local hardware man will recommend Plumb. FAYETTE R. PLUMB, Inc., Phila., U.S. A. LU pce eet Hammers Hatch latchets Files Sledges Axes MakRcH, Fy W busi wou that the | ers. used And For in fz goo. it a vest The dro] belc mea has atio ren Gre is W witl the

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, —_ +t = Marcu, 1930 For transport POPULAR SCIENCE MONTHLY ration of higher quality than could otherwise be enjoyed— good used cars afl. F you checked up motor cars wherever professional and business men congregate it would not be surprising to find that quite a number were in the hands of their second own- ers. In other words, they were used cars when purchased. And why should this not be so? For consider the exceptional— in fact unique—advantages the good used car offers that make it an extremely sensible in- vestment. The market depreciation that drops the price of used cars far below that of new cars does not mean, necessarily, that there has been a comparable depreci- ation in a used car’s ability to render service. Granted that the transaction is with an established merchant with a reputation to conserve, the buyer can count upon good transportation for many thou- sands of miles. This transportation is of a higher quality than the buyer would enjoy if he spent the same amount of money for a new car. In many instances, he could not buy any new car for the price he pays. ‘The fact that he is driving a used car in no way detracts from the impressive character of his higher-quality transpor- tation. After all, as has often been said, every car on the street, of whatever make or history, is a “used car.” There remains a word of cau- tion for anyone contemplating the purchase of a used car. Give careful consideration to the man from whom the used car is bought. Pick a reliable dealer who conducts an estab- lished business, sells a standard line of new cars, and has the good will of his community because he has earned it. Men to whom Cadillac-La Salle franchises have been entrusted are dealers of this character. They are whole-heartedly recommended. Their used car stocks are varied and reason- ably priced. Before you make a decision, regarding a used car, see what the nearest Cadillac- La Salle dealer has to offer. CADILLAC-La SALLE CADILLAC MOTOR CAR COMPANY DETROIT, MICHIGAN Division of General Motors OSHAWA, CANADA

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ee eee aa eee , : if p : f i t opular Science MONTHLY BRunded 1872 25 Cents a Copy Pop $2.50 a Year 381 Fourth Avenue New York, N. Y. Table of Contents for March, 1930 LEADING ARTICLES Astronomy Thousands Are Flying Gliders. . . . . . By Edwin W. Teale 19 ie wa wend vated Grow _— Ye Sport and thrills in a new national pastime A “Big Bertha” of Astronomy 47 How Pygmy Tugboats Dock a Giant Liner ._ . By Robert E. Martin 22 Builds Novel Telescope in His F Back Yard . 62 What happens when an ocean vessel is put to bed ieeasl Mine Dien ter ites te Threads That Swing 350,000 Tons . . ._ .By Frederick Tisdale 24 P pe How cables tie the world together in bridges and aerial railways Aut bil A New Figure in American Flying . . . By Alden P. Armagnac 26 utomoowes Peering into the future with Dr. Claude Dornier, giant seaplane builder Car before the Motor . 31 New Electric Auto Brake . 31 The Truth about Hypnotism . . . . . By Wesley R. Wells 27 Dustless Garage Cleaning 39 A professor of psychology “debunks” a much-misunderstood subject A Vacuum Gear Shift... 35 From Wood Pulp to Rayon Silkk . . . _- zk o OO The Car Makes Its Own Gas 35 Marvels of stockings made from trees explained j in s pictures New Carburetor for Fuel Oil 37 . Excess Humidity Reduces Auto Flying with an Airship Captain . By Lieut. Commander Charles E. Engine Power . . . . . 45 Rosendahl 40 Cover for Auto Motor 84 The skipper tells of navigating the Los Angeles Insulating the Floor 84 The Men Who Will Award Our $10,000 Prize . . 42 A Tin Can Cut-Out , 84 Introducing the distinguished members of the committee es aw and 2 Saas Sa . 4 The First Pneumatic Tire—Invented to Please a Boy. . By H. C. y terme bem Garage Light ; 84 Davis 44 Using a Spray Gun to Refinish How John Boyd Dunlop put the motoring world on rubber cushions an Automobile ‘ . 137 Build Great Dam in Record Time . . . .. .. By Earle Duffy 55 A mighty engineering feat that averted a water famine Aviation Was Your Dog Oncea Wolf? . ... . . By Stephen Sherman 56 Testing Balloon Tires for Planes . 52 New knowledge about the dog and his a ancestors Around the Air Circuit for a 5,000- ; l . . . . . By John E. Lodge 58 Mile Record - + 92 ara SEetney 7 pose ee ae ine & Automatic Plane Stabilizer 52 How mass production may revolutionize farming Safety Contest Winner 52 Beating the Weatherin the Air . . . . . By Assen Jordanoff 59 40-Passenger Amphibians . 52 What a veteran pilot has learned from battling storm and fog rms, Me Feet to R-101 . 52 How to Control Screen Grid . . . . . . By Alfred P.Lane 71 Close-Up Views of the World’s Curi Sa sega th oie Newest Dirigibles 53 MEINE SEREEES Sh CESS Thas UES She vp Napasaaa Automobile Engine Drives Plane 54 Easy Ways to Shut Out Man-Made Static . . . .By John Carr 73 Next—Beryllium Planes? . 54 Remedies for the noisy receiver New Curved Radio Beam ___. 54 Gus Explains Why Tire Chains Are Safest . . . By Martin Bunn 74 Mail Pilot Flies Million Miles 54 What to do when—and before—the car wheels slip . " Engineering Welded Steel Fl for High FEATURES AND DEPARTMENTS SS ere Tunnel Lined with Wood . 32 Cover Design . . .... . . . . . . By Herbert Paus An Eight-Ton Armful . 37 Fimancial Article . . . ....... . . . 4... 4 ; — Reduces Noise of Street 46 Popular Science Institute Page . ... . ~ « »« 2 Japan’s Three-Way Bridge . 47 as . Bucket Dredge Cleans " . 51 Our Readers Say ee Ce ae ce ae, Bh, a tw ee Oe (84 Weelen Water Mains Us. New Ideas and Inventions . ............ +. 29 earthed in London . : 62 Progressand Discovery . . . . ......... . 45 Twenty-Foot Water Wheel 66 i in Aviati ss aig 2. a «4 «0 %.0 ° aang She a ong ro Health and Hygiene Popular Science Scrap Pi + * © Be ee Ck ce te Surgery in the Movies and by New DevicesfortheHome............ . 6&8 st Lantern . $l Advocates Flying Clinics for Editorials ° . . . . . . ° ° - oe ° ° ° . ° .: 10 Frayed Nerves 34 Hints for the Radio F. Deeriew@wu «+ Qs sere .0acaeiee Automatic Device Records” Rhythm of Heart. 38 SIC ae ae ee ee ee ee ee ee Discovery of “Flu” Germ " aaeidite Useful Kinks for the Car Owner . ......... . & Confirmation ~~, « « March, 1930, Vol. 116, No. 3. Popular Setence Monthi » blished month- contents of this magazine must not be reprinted without permission. The editors iy at 381 Fourth Avenue, New York, N. Y., by the Pop’ ence Publishing are not responsible for unsolicited ene butions, and cannot guarantee the re- ‘on Ine. Entered as second-class matter Dec. 28, 1918, at the Post Office at turn of such material or Insure against ite lose. in presenting numerous stories New York under the act of March 3, 1879; additional ‘entry as ——— of new products of ‘applied science, Popular Science Monthly does not under- matter at Chicago, Illinois. Entered as second-class matter at the Fons write the suaenees methods of the individuals or concerns ene oo. oe Department, Canada. Printed in U. S. A. Copyright, a" the fk. use of Popular Science Monthly articles for none Seience Publishing Co., Ine. Single copy, 25 cents. su Delong to authorised. O; B. Capen, President and Treasurer; R. tison, Viee-Presi- United States, its possessions, and Canada, $2 Pole Counters es, The dent; A. L. Cole, Vice-President and Secretary.

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Popular Science Monthly for March, 1930 -Coolin Poor Food, Not High —_ the Cause of ‘lls ide Germs in Wound 11 Years 4 50 66 Laboratory Discoveries Rare Metal in Quantity. Huge X-Ray Tubes Produce Man- ade Radium Rays Dynamite Blast Miles a Second . Speeding Electrons Photographed on Metal . Grain Alcohol from Natural Gas “Diamonds from Sugar” ‘ cath Four Nature Strange Creatures from the Ocean Depths. Autumn Leaves Still Gay After Millions of Years. American Bald Eagle Is Near Extinction. How the Mother Birds Feed Their Young “The Most Repulsive Fish in the World” Giant Mushroom as Large a as a Hatbox ~ 2.’ a 30 45 45 50 50 51 New Devices for the Home Metal “Fingers” or Steel Wool Clip Holds Pasteboard Box Covers losed Tray and Serving Table Combined — Shredders Aid Salad- akin New Ree T Keeps Iron Cord Out of Way Electric Heater in Table Warms Chilly Room . Slices Tomatoes Evenly . New Home Electric Dryer _. Armchair becomes a Bed by Ni ht Auxiliary Electric Heater in Ra- diator Cabinet ; : Safety Kettle Pours Hot Water . Drip Percolator Shuts Itself Off . Hold Dishrag New Processes and Inventions eeding Up the Stock Ticker . Fog-Piering Lamps for Railway Saar" Safety Glass Resists Fire and Bullets. Slot Machine Deals Out W ater, Soap and Towel . Combination Stepladder Will Rest on the Stairs. . Knockdown Desk and Seat for the Schoolroom . Dust-Catcher Shields Train’s Ob- servation Platform -. A “Step-Over” wr Trolley An All-Purpose Saw Self-Sharpening Razor _.. Found—Easy Way to Open a Cardboard Carton ‘ Santos-Dumont Invents Life-Line Catapult .. the Telephone . Brush Holds Shaving Kit . New Electric Typewriter Prints Whole Phrases... , An Ingenious Lock Nut_. Subway Moving Sidewalk r 5 _ Takes the “Kick” Featherweight Office Furniture. Out of Rifle or Shotgun bas Automatic Chemist Saves Work in Laboratory. cha % Aluminum Playing Cards . Photography High-Speed Photo ene Make hirring Wings Stand Still. New Camera Standardizes Rogues’ Gallery Photos Home Talkies Arrive ese Shotgun “Camera _ Cartridges” ane z rtsman’s Aim. roa s Eyes to Find Secrets ision . Pe Fi iting Voices to Faces Radio Radio-Sound Fog Signal Ship-to-Shore Telephone Service pened Rewiring for ‘the New A.C. Tubes Use Headphones for “DX” ; A B C’s of Radio : Ships Steam and Diesel Engines Drive Speedy Warship . ; Submarine Rescue Tube. Expedition Sets Sail in Vibration- less Yacht Largest of Submarines Launched in France... First Electric Train F erry 37 1 38 RES 30 33 36 46 47 Unusual Facts and Ideas Sun Baths on the Train Chemicals to Remove Snow . New Grade Crossing Signal Light Steam-Heated Gardens... Fighting” atop a Railroad Fires with Streams of Pow er. Burned Toast Filled with Invisible Diamonds? : Household Ice Boxes May Go “Dry,” Too Panning for Gold—The Old ‘and New Ways. Forestry Weather Bureau Travels by Truck . Tomatoes, Potatoes Grow on "the Same Plant New Gas Treatment Ripens F Fruit in a Few Hours . ; “Theater of the Future” . Umbrellas Sold by Slot Machine Foresees Electric Heat from “*Coke Batteries” Evidence of Nerve System Found in Plants... How Much Do You Know about Mechanics? . An Artificial North L ight for Color Matchin Measuring New York ¢ City Noises An Electrical Garden . Italian Troops Scale the Alps Single File Mystery in New Blue Gem ; Tells Why Mayan Prayers Brought Rain . Men Win Race with Rats ; bg Tanks Nest at Top of hty-Foot Tower. .... . The ey Traffic Problem . More Ways than One to Catch a Fish 64 4 Grinding Soft Rubber . r Ice Crystals Ages Old Roping Wild Elephants in the ungles of India . 66 67 For the Home Owner | Dustless Garage Cleaning Handy Rack Provides Storage . How to Remove White Spots from Mahogany Tables_. — Electric Wall Fit- egetable ings Raptien Old Patty from Win- dows . Boiler Injector Removes Water from Cellars . Mending Broken Pieces of Earth- enware Woodworking Seascoot—A Family Motor Boat Learning to Use a Small Lathe Tapestry Upholstered Bench . Modernistic Radio Cabinet Craftwork Building the Body of the Diamond Tally-Ho . . ; a Sole Leather Box . Wall Vase of Hammered Pewter . Making a Candle Side Light . A Glue for Leather _. How to Rejuvenate Old Oil Paint- Easily Constructed Block Puzzles —. for Building Model Air- es . Makin a Child’s Toothbrush Holder ere 32 110 110 120 126 134 135 86 98 100 . 102 112 126 133 134 . 135 Ideas for the Handy Man How to Use a Soldering Iron... Doctor Finds Home Workshop Restful after Day’s Work . . Handy Sander for Small —— Surfaces . Simple Joint for Windows. Putting an Edge on a Pocketknife Blueprints for Your Home Work- mop”. wo BS Pets How to Make Flashlight Cells Seven Motorized Shop Aids Adjusting Doorbell for Trans- ormer How to Truse-Wind a Bait Rod . A Modern Dog House . Amateur Constructs Concrete Building Wiring a 2. Building Against Bur- glars . Entertaining with Musical Car- toons . + ip ere 82 96 104 104 106 108 : 12 ’ 114 116 124 130 134 136 . 140 Hints for the Mechanic Twenty-Five Hints i in Using Wire Old Bill Sa > Easily-M ~ Cutter Removes Burrs. . Boring a Ta ‘in a Small Lathe Two Angle Irons Hold Work to Be Come ne se Emergency Bushing for Pulle Fapepiate a i Design oa Lathe Work Wooded Covers Protect Ways on Idle Planer. ai rah 90 92 92 92 . 104 116 . 118 118 . 126

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POPULAR SCIENCE MONTHLY Marcu, 1930

EFF MARLEY was scared. With J thoroughly justified fear he viewed the immediate financial prospects of himself and his family. And well he might. No one could exactly accuse Marley of being improvident. He had worked hard —too hard for the good of his health. His family had lived comfortably, but mod- estly, so that Jeff had been able to accu- mulate enough money to buy an interest in the small financial firm of which he was vice-president. But his whole stake—all the money his family would have to live on in case of his death—was tied up in the future success of his business. For two or three years Jeff Marley had seen the value of his investment in the business show a nice increase. As recently as October 1, 1929 he had remarked to his wife that their original investment of $5,000 had attained a value of $20,000. Both agreed that they were getting the breaks. Little did they realize the un- favorable developments which were just around the corner. Early in October Jeff took to bed with pneumonia. During the stock market panic he was too sick to read the news- papers or get reports from the office. When he was finally able to return to work he found a strange and deplorable reversal of the conditions which just a few weeks previously had looked so rosy to him and his wife. The firm had escaped bankruptcy, but its orderly liquidation meant the cancellation at a total loss of the stockholdings of the operating execu- tives. His job was gone; his income cut off; his estate wiped out. HE fates had dealt an unusually jolt- ing lesson to Jeff Marley. His narrow escape from pneumonia and simultaneous financial loss had driven home with too cruel force how fragile was the basis of the Marley family’s financial welfare. So Jeff was haunted with a double fear. Where would he get a job? In the event of his untimely death, on what would his family exist? ‘“‘You never seem to worry.” “Why should I?” With no attempt at disguise did Jeff Marley thus express his envy and admira- tion of the contented outlook on life held by his good friend and neighbor, Craig Wright. And since Craig was not one of those professional optimists . . . ‘‘just singing in the rain” . . . but on the other hand had good reason to view the future with contentment, his natural answer was ‘Why should I worry?”

How $680 a Year Increased Craig Wright's Estate From $12,000 to $42,000 By WALLACE AMES, Financial Editor ‘‘Why should you? A question more to the point is ‘Why shouldn’t you?’” sug- gested gloomy Jeff. ‘‘When we dropped in this evening you said ‘Happy New Year.’ But do you realize that you might get sick unexpectedly, just as I did, and you might not be fortunate enough to recover. But if you should recover, as I did, you might lose your job and your money in one fell swoop. Did you ever stop to consider what you would do if you were dealt the blow that struck me recent- ly? Or what your family would do if a little germ bumped you off?” The old adage ‘‘ Misery loves company” is probably a more nearly correct explana- tion of Jeff’s gruesome conversation than a desire to help Craig avoid difficulties —_ to those that were preying on his mind. “CURE, I have considered those possi- bilities,” replied Craig, not in the least disturbed by the picture of possible horrors which Jeff had drawn for him. “I considered them long ago, twelve years ago, to be exact.” “Well then why don’t you worry? You’re not dumb enough to believe that your luck will go on forever.” “‘No, I am not that dumb. I am not trusting to luck at all, in fact. I am well protected against the contingencies that you have so cheerfully and so dramatical- ly suggested.” “‘Protected—rats! No one could have been better protected than I was, but look at what happened. I was sitting on top of the world, but the top turned out to bea volcano, and when the eruption took place I fell right into the crater.” “Nothing you say changes the fact that I am well protected, so I should worry.” “If it is not too inquisitive may I ask how you are so well fixed to vanquish any unexpected misfortune?” “T’ll be glad to explain,” replied Craig. ‘‘Perhaps my plan will be of some help to you. It is not patented. You are welcome to work the same plan if ydu like. ‘When I reached my 28th birthday I had saved $1,000. At 514% this paid me $55 a year. I took out a $3,000 life insur- ance policy on which the yearly premium deposit was $56.70. The income from my investment was reserved to pay for the insurance. Thus I immediately increased my estate from $1,000 to $4,000. “Then I established a fixed policy of saving a reasonable portion of my earned income each year (Continued on page 5)

Mat rn, ae ae ae Ce ee se ee eo i oo El on cae} —< ~ Sete Go 8G

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L930 i -— _- > Marcu, 1930 ieee $680 a Year Increased Craig Wright’s Estate From $12,000 to $42,000 (Continued from page 4) and at the end of the year invested it in securities. I did not put my savings in speculative securities, but was influenced entirely by safety considerations. On an average my investments have returned 5%9% income and from year to year I have taken out as much additional life insurance as that investment income would pay for. “In the beginning my salary was $3,000, of which I saved and invested $500. Each year I got a moderate salary increase. Up to dge 35 I managed to save about 16% of my earned income. From then on, when my salary was $5,000 a year or ‘higher, I saved and invested a little over 20% of it. Up to my last birthday, w hen: I was 40 years old I had series of life insurance policies now total estate is $41,950. NCOME from $12,450 at 54% amounts to $684.75; the total deposits, at the rates at which I took out the several policies, is $680.61. So the one almost exactly offsets the other. “That, by the way, is one of the many | interesting little side features of my plan. Everyone I know has to scurry and scrape payments for two or three months after they become due. Or to pay the insurance companies with notes. Obligations that come dueat regular, but unfrequent inter- vals seem so hard to meet. Lack of pre- paredness in this respect seems to be a trait of character with all salaried per- sons. Personally I have never been annoyed over the receipt of premium notices. I just clip a bond coupon or cash a dividend check and pay the money over to the insurance company. All I have to | do is to save a regular amount out of each | salary check. The rest of the system runs itself. AVE I answered your question, Jeff, as to why I do not worry over future misfortunes which may some time overtake me?” “Yes,” replied Jeff, “and more. You have put a real idea into my head. I am glad your system of estate-building is not patented. Even if it was I would be will- ing to pay a royalty to be able to use it.” Based on the Craig Wright method of providing substantially for his family, we have compiled a simplified table to show just how the plan would develop from year to year. The table is presented with this article with the following explanatory comments. First we assume that Craig Wright earned $3,000 during the year ended on his 28th birthday, and that beginning on his 28th birthday he had $1000 invested at 54%%. Then we allow him a normal yearly increase (Continued on page 6) amount of my life insurance premium | saved $12,450 out of earned income., My | $29,500. So the present value of my | to meet his insurance payments. It seems | to be popular practice for policy-holders | to let their insurance agents carry their | POPULAR SCIENCE MONTHLY The Provident Thrift Policy What It Will Do For You If you live e « « it pays you $10,000, or the face value of your policy, atage65. This plan establishes a capital quietly accumulated during your productive years to take care of you in your old age. If you die e « « before age 65 your wife or children or heirs will receive $10,000 cash, plus any accumulations. A monthly income (plus excess interest) may be taken in place of the principal sum. Double the amount of the policy will be paid if death results under conditions covered by the Accidental Death Benefit Provision. If you become totally and permanently disabled .. .vetore age 60—you, yourself, will receive $100 per month ‘and will be relieved of paying any further premiums, while such dis- ability lasts. Moreover you will receive the regular annual dividend. In addition to these benefits your policy will be paid in full at your death; or if you are living at age 65 the $10,000 cash will be paid you as described above, and the disability income will continue so long as you remain totally disabled. ~COMPLETING THE CIRCLE OF PROTECTION 'N OW.. . while you are insurable and can spare the money, let us tell you how small a yearly saving will put this Thrift Policy into action for the com- fort of your old age — or for your family’s comfort if you die. Just fill in the information called for on the blank be- low and mail it to us and we will send you full particulars without delay. Low Ras ‘Provident Life Insurance Company of Philadelphia Penna. Founded 1865 Low Cost... “Mutual You may send me full information and quo premium rate for a Lape Thrift Pulley: with the understanding that it places me under no obligation. I was born Month Day Year My name is. My address is. © 1929 P. M.L. I. Co.

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How $680 a Year Increased Craig Wright’s Estate From $12,000 to $42,000 (Continued from page 5) in salary and estimate his future yearly savings according to his statements to Jeff Marley. We ignore all irregularities, such as market profits or advancing values in his security holdings, extra divi- dend disbursements, etc. and assume that his investment income was exactly 54% of the amount saved and invested each year. Thus the first three columns of the accompanying table give the basis of working out the possibilities. The form of insurance figured on is Ordinary Life. So as not to complicate the calculation we have ignored the factor of policy dividends. In a term of years these would aggregate a considerable sum, which could be used to reduce the net premium deposit, or buy additional insurance. Because of the way insurance rates are figured it is not possible to match up premium deposits and invest- ment income exactly, but in the table the difference between one and the other is always negligible. CCORDING to our computation Craig Wright earned $61,000 be- tween ages 28 and 40. Whereas he saved only about 20% of this the total value of his investment-insurance estate is nearly 70% of his total earnings. It is entirely prohable that any man who operated the Craig Wright plan over a period of years would be better off financially than our computation shows, for either or both of _two reasons: Properly selected securities will gain value; policy dividends would improve the result. Trust companies now operate insurance trust departments, rendering to individ- uals just such a service in estate-building as Craig Wright worked out for himself. You may deposit income-bearing securi- ties with a trust company and they will attend to all the details for you. Or, if you have not yet acquired the securies you can start now to get them, a little at a time. It is amazing how rapidly you can make your estate grow, safely, if you just work some such plan as Craig Wright’s. Buying an Estate of $41,950 With the Income from $12,450

el e2is |s 2 > | & =3/ 2 ee if S a |ee/ 28/2/52 ]/8 |= | =3 3 a. 23 | oa ¢ 2 oD aa) 28) ss/e5/3 | 8 | 82 2 egi-s a | @a}/aa |e] re - = > S bo 3 3 ao g| = | #2] ax | e8| 3B | 24 | 34) 33 2| © |@8| xs] 2/&2| &o| es ® $1,000|$55.00/$56.70/$3,000 28 |$3,000} 500} 27.50] 18.90] 1,000|$4,000|$1,500|$5,500 29| 3,250] 500} 27.50| 29.12] 1,500] 5,500] 2,000] 7,500 30| 3,500} 500) 27.50} 29.91) 1,500] 7,000| 2;500| 9,500 31| 3,750} 600] 33.00| 30.77] 1,500| 81500] 3,100111.600 32| 4,000} 600} 33.00] 31.65) 1,500|10,000| 3,700113,700 33| 4,250] 750] 41.25] 32.60] 1,500|11,500| 4,450115,950 34| 4,500] 750] 41.25] 44.78] 2,000/13\500] 5,200/18,700 35| 4,750} 750] 41.25] 46.20] 2,000/15,500] 5,950/21,450 36 | 5,000] 1,000] 55.00] 47.68] 2,000]17,500| 6,950|24,450 37| 5,500] 1,000] 55.00] 61.55] 2,500]20,000| 7,950|27,950 38| 6,000] 1,500] 82.50] 76.35] 3,000/23,000| 9,450/32,450 39| 6,500} 1,500] 82.50] 78.99] 3,000|26,000] 10,950|36,950 40| 7,000! 1,500! 82.50| 95.41] 3,500/29,500/12,450141,950 Earned during year ended at given age. 2)Approximating 16% of earnings each year ending at age 35 and 22% thereafter. @Amount previously saved go plan becomes effective at 28th birthday. (Continued on page 7)

Marcu, 1930

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- FIDELITY BONDS Fidelity Bonds are conservative first mortgages on new income producing “real” property. Every dollar invested in Fidelity Bonds is secured by brick, mortar and land that is so situated as to be constantly increasing in value. At the same time, the amount of the loan represented by the bonds is being reduced and the security is becoming that much greater. That is why we can guarantee every Fidelity Bond at maturity. Make your invest- ments yield you a SAFE 6%. Let us send you, free, a copy of the booklet “Your Money—Its Safe Investment.” I BOND # MORTGAGE ry

J3.U.MENTEER .Preoident ew 660 Chemical Building, St. Louis 1188 New York Life Bl ig, Chicago 378 Colorado Nat’! Bank 'g-, Denver N1000 Nae ee ee ee ee ae ee ee ee ee eee LEQ LO LOO LOLOL LOL ONL ON LON ON FN DD flO lO Om fm LO LO, ff, ff,

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~S=™. Marcu, 1930 : $680 a Year Scene Craig Wright’s Estate From $12,000 to $42,000 (Continued from page 6) In addition to the table which shows how Craig Wright built up an estate of $41,950 by using his investment income to carry life insurance, there is also appended to this article a table of ordi- nary life rates on the 314% reserve plan for men of various ages. Referring to this table and taking into consideration your present salary and possible savings schedule, you can easily determine the value of the estate you might create by working the Craig Wright plan. May we suggest that you do just that. An evening spent with pencil and paper will reveal some startling and stimulating possibilities growing out of a practical combination of investment and _ life insurance. And what easier way could you find to carry adequate insurance protection than by paying premiums with your investment income. When you have finished your own figuring we suggest that you consult an insurance adviser. Describe your plan to him and he will doubtless help you to adjust the details to your greatest ad- vantage. He can point out many possi- bilities not within the scope of this article. Ordinary Life Rates 312% Reserve Situation at age 40 Total Investments........... $12,450. 54%% Income from Investments...... $684.75 Total Insurance............. 29,500. Total Annual Insur- ance Deposits. . . . $680.61 , ee 41,950. [ Annual Annual Annual Age Prem- Age Prem- Age Prem- ium ium | ium 25 $17.52 32 $21.10 37 $24.62 28 18.90 33 21.73 38 25.45 19.41 34 22.39 39 26.33 30 19.94 35 . - 31 20.51 36 23.84 45 32.89 3 To Help You Get Ahead TS 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 Cochran & McCluer Company, 46 North Dearborn St., Chicago, III. How toGet the Things You Wanttells how you Can use insurance as an active part of your rogram for getting ahead financially. 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 jan will bring you financial independence. rite for this klet to Investors Syndicate, too North Seventh Street, Minneapolis, Minn. POPULAR SCIENCE MONTHLY ol ‘ A GUARANTEED INCOME ror LIFE $250 a month beginning at Age 55, 60 or 65 HE Phoenix Mutual announces a new Retirement Income Plan under which you get not only immediate protection for your beneficiaries but also, for yourself in later years, a guaranteed income you cannot outlive, What a $25,000 policy, payable at age 60, will do for you It guarantees to you when you are 60 A Monthly Income for Life of $250.00 which assures a return of at least . $25,000.00 and perhaps much more, depending upon how long you live. Or, if you prefer, a cash settlement - . sss $33,750.00 It guarantees throughout permanent total disability which begins before age 60 A Monthly Disability Income of . $250.00 and the payment for you of all premiums. It guarantees upon death from any natural cause before age 60 A Cash Payment to your beneficiary of $25,0c0.00 Or a monthly income as long as your beneficiary lives, It guarantees upon death resulting from accident before age 60 A Cash Payment to your beneficiary of $50,000.00 Or a monthly income as long as your beneficiary lives. « Send for the Facts The plan above is for $250 a month, payable at age 60. You may arrange to retire at other ages than 60 if you wish. You may provide for yourself a Retirement Income greater or smaller than $250 a month. Plans for women are also available. Other things you can provide for by this program are: Money to leave your home free of debt. An income for your wife in case she should outlive you, Money to send your children to college. Money for emergencies. Money for special needs. There is hardly a financial problem which cannot be solved by this plan. A Retirement Income does not have to be paid for all at once. It is usually paid for in installments spread over a period of 20 years or more. Naturally this fed the individual installments comparatively small. One of the great advantages of this plan is that it goes into operation the minute you pay your first installment. From that moment on, you guarantee the fulfillment of your life plans. Even though you should become totally disabled and unable to make another pay- ment, your payments would be made by us out of a cash reserve provided for that pur- e. Your home would be left clear of debt just as you had planned. Your children would go to college, expenses paid, if you had planned it so. And you would have $250 a month to live on while disabled, even if ‘reed disability should last the rest of your life. We should like to send you an interesting 28-page book called “ How to Get the Things You Want,” which tells all about the Retire- ment Income Plan and how it can be exactly suited to your own special needs. No cost. No obligation. Send for your copy of this free book today. 6) PHOENIX MUTUAL LIFE INSURANCE COMPANY Home Office: Hartford, Conn. First Policy issued 1851 Copyright 1930, P.M. L. I. Co. PHOENIX MUTUAL LIFE INSURANCE CO., 498 Elm St., Hartford, Conn, send me by mail, without obligation, your new book, “How TO GET THE THINGS You Want.” Name Date of Birth Business Address. Home Address

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8 POPULAR SCIENCE MONTHLY Marcu, 1930 Guaranteed Advertisement Automobiles and Accessories Page Musical Instruments Page Educational (continued) Page Cadillac Motor Car Company 1 Buescher Band Instrument Co............ 134 School of Engineering of Milwaukee. ...... 162 Houde Engineering Corporation ; —_— - 4. errr 142 Standard Business Training Institute. .... 156 Oakland Motor Car Company # SONS SS 2 See 136 Tamblyn, '!F. W..............---- +e e es 156 Studebaker Corporation of America, The 89 Mussehi & Westphal..................... 116 Tri-State College... --.................. 152 RE MEIN os oo vec ca dcccassesesens 85 Pan American Band Instr. & Case Co...... 118 Universal Plumbing School............... 153 Petersime & Son, IraM.................. 148 University of Chicago.................... 152 Building Materials on Re os Rieke TC 120 Sane ie Gecieeding toss Deets e eee e eee eee br u g a e ee a nt 18 Razors, Toilet Articles, Etc. a ey NE 5%. . cecncs lade d tiee ee 120 Autostrop Safety Razor Co............... 96 © AGF Masonite Corporation................... 13 SS SE er 122. Aluminum Company of America........... 168 ES EC Oe ko 64 a o's eedeton cw dled 141 ee ee eee 122 k Lambert Pharmacal Co.................. 17 National Carbon Co................-..5. 103-114 Books een 3 rE NS Aanabepaeesoee se onee = Radio-Victor Corporation of America...... 81 ee ee I I bois deeb dave cecdiosedae 163 Williams Co., The J. B 104 Aviati Clarkson Publishing Co. okt Lay 154 ” . i ee viation Encyclopaedia Britannica, Inc............. 9 American School of Aviation 164 Merriam Company, G. & C............... 154 Vina tin—e ecess. 060mm re oO eee 150 oneal nea ed) Se po Lincoln Airplane & Flying School.......... 146 tence News-Letter............-.++s++0+ 1 ° Pacific Technical University.............. 148 Popular Science Universal Aviation Schools............... 162 ciciaiiiaen oo... - GUARANTEE Sporting-Goods and Toys erican Wnime Vl0ce LO..........------ Automatic Rubber Co.................... 120 Breidert, George J.........-.-.-. +. eseees 118 GIN MINE GIDL. 3 3 vcccccsesevecccess 98 Craftsman Wood Service... ......-..... 138 © Harley-Davidson Motor Co............... 143 SE INI 5 5 os i cde ncescccces 118 Kingsbury Mfg. Co. 120 Ideal Aeroplane & Supply Co., Inc......... 142 POPULAR SCIENCE Bleed @ydte Ge.......................-.. 2D ly a» ne» SP a a MONTHLY guarantees every Old Town Canoe Co... 138 Modal ‘Sha se : S, AMC... ..-- eee eee ii article of merchandise adver- Porter Chemical Co,.............-sses00s 118 — hip Supply Co..............-.--. 6 ; @ Smith & Sons Boat Co., Chris............ 139 grrr rere 120 tised in its columns. Readers Thompson Bros. Boat Mfg. Co............ 142 who buy products advertised Investments in POPULAR SCIENCE Industrial Equipment Cochran & McCluer Co................-- 4 MoO N THLY may expect them American Screw Con. .......-.ccceccccses 111 Fidelity Bond & Mortgage Co............. 6 to give absolute satisfaction Chicago Gear Works... .........ccceees 138 Investors Syndicate. . Pe eats ee 6 under normal and ro ruse. ee 4 ow a's cw reraesb edie dave 138 Phoenix Mutual Life Insurance Co. 7 Is. Radi a ° Re Sec ce k baadceseed ne 95 Provident Mutual Life Insurance Co....... 5 Tools, Radio Apparatus, Oil S. K. F. Industries, Inc.................. 83 Burners and Refrigerators ad- Taylor Instrument Companies............ 166 “ae 2. eid vertised in POPULAR SCIENCE po Serer eee 140 ools an op Equipment MONTHLY have been: tested or Arkograf Pen Co...............00e00000: 128 investigated by the Popular ——_ saaes. Antemnaye — & Gam Ec . 113 Science Institut f Standard TOI, BIO Bike a 55s 56s sccced icaces 161 Boi W.B Oe ste ew eeecees 120 n stitute oO ndards Evans & Company, Victor J.............. 159 ee tne Be inns aban 101 and each advertisement carries Fisher Mfg. Company, Adam............. 161 a4 re a ees The. ...- a the insignia indicating ap- et A AEE 4 Carborundum Co., The.............. 110 proval. roa? eee Pa eas eet n ? ; SS ee ee cree ve ee 160 Delta Specialty Company.............. - 116 However, other products Lancaster & Allwine.................+5-. 158 Disston & Sons, Inc., Henry.............. 87 A A ° McCath I 1 Farrand, Inc., Hiram A................ 119 advertised in the magazine OB ~ "Cla ne et ee eee be Flash Sales Corp., The................... 126 not subject to test carry the ge ye = hw lel ll lel ter cteltaeh 57 Fo ley Manuf facturing ee ce eee 134 same guarantee to readers as Randolph & Company.................-- 161 ae products tested. Hardware Supplies I coc enccccccceseess 138 Boston Varnish Com tere eee 108 Goodell-Pratt Co..............%...2.-.-. 105 THE PUBLISHERS Casein Mfg. Co. of America, The.......... 132 Greenfield Tap & Die Corporation 115 Detroit White Lead Works 3rd Cover I ME, os oo nc weicnceesice oes « 142 a i a a a 106 ne elas 6 6 6 Gus 6 6.0.0.00 566.0 144 N Inc., W i F. ice or es eee ee, 142 lennings Mfg. Co., The Russell........... 138 “an , HERE Saedl $< cee re ae) aydole Hammer Co., The David... 165 Educational Piste Wom RE neh ne ee 136 American Sch. Mech. Dentistry........... 156 Savogran Company...................... 129 Nicholson File Company................. oo Sr as need Gee) Me, Re 109 North Bros. Mfg. Co.. epee Met 133 iss Electrical RR rane? oe 162 ooster Hrusnh CO., LN... eee ee eeeeeee MPGIND, TOMEI Tle. 5 8 cc ccc ccce vices 162 — fo eens Machine Co., , ae be pene = hip nen era ae ee = Business Opportunities od; hha ; ica echnica’ e SAP iste eee ine Fe OTS 2d Cover Cody School of English, OE SEES ee a 160 Ree als #9 CMR Sa s+ 46 98 Be Columbian ae eee 163 Central States Manufacturing Co......... 148 Simonds Saw and Steel Co eee e eee ees 94 Cooke School of Elec.,L. L............... 156 Edisco Men’s Wear...................... 136 hh de 122 Coyne Electrical School... 022-022. .22:. - 7 + ~~ ~ppeb eppepbepener seneeene 161 Bis Aw Siena oh ds Sas tt cers Soceee Detroit School of Lettering.............. 162 Elmwood Mfg. Co...............e0-eeees 160 — Stanley Rule & a Plant, The.......... ee i cn neccdecsecs ee eee 161 Starrett Co., The L.S................--. 91 Federal School of Illustrating............. 149 Foley Manufacturing Co.................. 134-144 Trimont Manufacturing Co., Inc.|... 125 Finlay Engineering College............... ee, Ge Me ok on sicc a namacsensies 146 tcp wet 1 aah See seer eereeeeces 126 First Hawaiian Conserv. of Music......... 152 ES ee ee ar 144 Wa om va , _— Cece eesececrcrons 99 I IG, oo dws. sin 6's :0:9 «04 082 5 5% SO |) ME Ts sacle SoS chk cesnewkee see 150 Walk Tr ” J. Sinee- sre henses seg 127 Hamilton Institute, Alexander.......... 4-130-160 Kriss Kross Corporation....... Gor svceses 164 EE iy BR. loins i ccccensccas 118 International Correspondence Schools... . . Ss er a oo Dig Picals acces et che teent = andon School of Cartooning............... eG BMCCOT GO... 22. cc wcccsccvesine General La Salle Extension University........ 148-158-150 I Bera oh ot oral a ica Sa a aien Weleres 154 American Telephone & Tel h C 10 po ow 4 roe Mechanical Dentistry. . 133 Sener poms nod Re werent 190 m pho elegraph Co....... rrie ool of Mechani tistry. . er. ok wane besbee dood General SI 6.5.4 6 09,6600 05000000000 11 Motion Picture Operators School......... 164 gk. Ee re eae ey ee ere 144 Silent Automatic Corp................... 137 National Electrical School................ 158 A Williams Oil-O-Matic Heating Corp........ 112 re nee —— — ara acexcogsee- = Miscellaneous ‘atio’ IE, oi Es. 0 aicig.necigrae « ; sos * National School of Cartooning............ 163 Bureau of Inventive Science.............. 158 Typewriters, Writing Materials, Etc. New York Electrical School, The.......... 150 Campbell Co., Wm... 2c cee cence, 122 Esterbrook Pen Co...................... 100 Niagara School of Music................. Se | RR Oe ns cc ansrccasass 144 wean Sype moe woe pigs aes? : - | mates _— SR Re 146 a, Corp. Des bkahsseun ddabeeees = Smi rona iypewriters, inc., L. C.... ia ES EE PI 152 sey IRL, iss add dice viretcatalaa s <b bod es Voice Ins of America.............. be og _——_ he oar se fpahaten ee Te 7 ; ‘ erfect Voice Institute...............: bios 52 ational Vulcaniz “rarer ; Smoking Materials Petroleum Ne ee 154 Plymouth Rock Squab Co................ 142 ea OO Back Cover Radio & Television Institute.............. ee CO OND RES Arp eres bree 142 Larus & Brother Company........... as CS -Oaec ecc BSPeies ces — Ac 4 5 Se iC eoege ene 144

MARCH. fo: Br en an icc fla § @& ea

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1930 oes l wv www eww Oo Marcu, 1930 POPULAR SCIENCE MONTHLY Greatest ENCYCLOPAEDIA VALUE ever offered the American People _... Completely New Encyclopaedia Britannica $45 BOOKCASE INCLUDED This handsome bookcase table, made of genuine Brown Mahogany, is included with every set of the new Britannica except in the Special Library form. can now own this newest, finest Encyclopaedia Britannica! Mass production on a scalé never be- fore possible brings you this superb 14th Edition at a new low price—the lowest at which any completely new Britannica has been offered in more than 60 years! Fen FAMILY, every wide-awake man or woman, Never before in the history of encyclopaedia publishinghas such an opportunity been given Amer- ican readers. More For Your Money A $2,000,000 Work When you buy the new Encyclo- paedia Britannica you buy sound built- in value that is little short of amazing. Nearly three years of intensive edito- rial effort, the best work of 3,500 world- famous contributors,the expenditure of $2,000,000, these are highlights in the preparation of this superb 14th Edition. At the present low price the new Britannica represents greater value for your money than any other book published. You get the equivaient of 500 ordinary books in the text matter alone—and at one-tenth their anics, worth many times the cost of the books. Full page halftones, color plates and sumptuous gold tones make vivid every section of the new Britannica. You get the writings of 3,500 authorities — of men and women whose services only the world- wide prestige of the Britannica could command. Here is authority, ac- curacy, fresh interpretation direct from the best minds of the century. You get up-to-date knowl- edge—the time proven learning of the past, the latest discoveries of today, the promised progressoftomorrow.New facts, clearly interpreted, give freshness and interest to every ‘paragraph. You get a wealth of practi- cal information for every member of the family. It answers every “what, “who,” “why” and “when.” But it also answers ten’ thousand “hows.” It is the finest guide to doing things For every American home the new Britannica with handsome bookcase table,its superb bindings,its wide range of help for work and play, is a center of interest for every member of the family. SPECIAL $ DOWN OFFER—only Large scale production makes pos- sible the present amazingly low price. A genuine mahogany bookcase is in- cluded with each set, and a deposit of only $5 brings the 24 volumes and table to your home. Balance may be paid in convenient monthly payments. Send For Free Booklet Send for the handsome new 56-page booklet containing numerous color plates, maps, etc., from the new edition and giving full information about it, together with details of bindings, low prices and easy payment plan. You needn't risk a cent. The book- letis yours FREE,with- out the slightest obli- /{7/ gation. Now—while you have this page at hand—tear out the coupon and send it in. ever published. ENCYCLOPAEDIA BRITANNICA, Inc. cost. Here is literally the sum total of human knowledge in 24 compact read- able volumes! You get the varied richness of 15,000 illustrations—paint- ings, photographs, maps and drawings,a unique gallery of art, science and mech- You get, in short, what crit- ics have called “the finest ency- clopaedia in English”—a book that brings you fully half again as much material as any other encyclopaedia or general refer- ence work published today. > SEND FOR FREE BOOKLET TODAY 342 Madison Ave., New York City P.S.M. 3 E2 ‘Please send me by return mail, without any obligation on my part, your 56-page illustrated booklet describing the new Britannica together with low price offer, etc. ° Name Add City, State.

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10 POPULAR SCIENCE MONTHLY Marcu, 1939 THE TELEPHONE BRINGS THE ADVANTAGES THAT COMFORT AND CONVENIENCE GIVE TO LIVING ‘This is the telephones mission An Advertisement of the American Telephone and Telegraph Company IN THIS COUNTRY, a new type of civiliza- tion is being reared—a civilization of better opportunity for the average man, comfort and convenience, business enter; prise and higher standards that enrich the daily life of all the people. To build for this new age, the Bell System in 1929 expended more than 550 ° million dollars. These millions were used to add new plant and further improve service. Hundreds of new buildings, mil- lions of miles of wire, chiefly in cable, eight hundred thousand new tele- phones—these were some of the items in the year’s program of construction. At the same time, better records were made for speed and accu- racy in service. . This American development of instan- taneous communication, of fast, far-reach- ing speech, belongs not to the few, but to the many. It is the aim of the Bell System to permit each personality to express itself without regard to distance. This is part of the telephone ideal that anyone, anywhere, shall be able to talk quickly and at reasonable cost with anyone, anywhere else. There is no standing still in the Bell System. MaRcH The co! nage 0 Dewey’ battle Bay W tons—] _tonna Pennsy sister Califor: Virgini electric vessels ice of Pacific ~ = + 4 SF tv Oo OO me ] 4 i ( ] j

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1930 Marcu, 1930 The combined ton- nage of Admiral Dewey’s fleet in the battle of Manilla Bay was 19,000 tons—less than the _tonnage of the Pennsylvania or her sister ships, the California or the Virginia, the new electrically driven vessels in the serv- ice of the Panama Pacific line, For THE Home — General Electric and its asso- ciated companies manufacture a complete line of electric products and appliances, including G-E MAZDA and G-E Edison MAZDA lamps, G-E refrigerators, G-E fans, G-E and Premier vacuum cleaners, G-E wiring systems, Edison Hotpoint ranges, percolators, toasters, and other Hotpoint products, Thor washers and ironers, and Telechron electric clocks. For Inpustry—Several thousand electric products and appliances, including generating and distribut- ing apparatus, motors, electric heating apparatus, street lights, floodlights, traffic lights, airport lights, Cooper-Hewitt lights, X-ray equipment, motion- picture apparatus, electric locomotives and equip- ment, street-car equipment. GENERAL@ELECT JOIN US IN THE GENERAL ELECTRIC HOUR, BROADCAST EVERY SATURDAY AT 9 P.M., E.S.T. ON A NATION-WIDE N.B.C. NETWORK BIGGER than POPULAR SCIENCE MONTHLY 11 Dewey’s whole fleet UILT not for war but for peace, the 35,000-ton S. S. Pennsylvania is not only bigger than all the ships of Dewey’s heroic squadron put together, but more efficient than any of them. Her 17,000-hp. motors have enabled the Pennsylvania and her sister ships the California, and the Virginia, to cut the coast-to-coast schedule of the Panama Pacific line to thirteen days, and have set a new standard of noiseless, vibrationless ocean travel. General electric engineered and built the electric equipment of these magnificent new vessels. Other General Electric research scientists and engineers are doing equally important pioneer work on land and for the new traffic of the air. The G-E mono- gram appears on thousands of electric products and appliances as a symbol of research, an assurance of advanced electrical correctness, dependability, and service. RIC i)

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5 I re 12 Measuring the hardness of the steel in a pair of pliers. The instrument used is the scleroscope. HE equivalent of years of every- day wear is given in a few minutes to tools undergoing tests in the laboratory of the Popular Science Institute. Some of these machines seem almost human in their movements and tell accurately facts that years of usage would only partially disclose. One of the most interesting of the testing devices is the torsion machine, shown at the bottom of the page. It tells three important things about a hammer. It determines the strength of the claws, it tells how well the hammer head is fas- tened to the handle, and it establishes the quality of the wood in the handle itself. As the engineer looks on, a mechanical hand two hundred times stronger than a human hand pulls the handle of the hammer, whose claws clutch the head of a heavy wire naii. The nail itself is clinched to the bed of the machine. A dial, which the engineer is shown reading, meas- ures the strength of the hammer’s claws. Then, after certain other tests have been made in differ- ent machines on the head of the hammer, the tool is once more placed in the torsion machine. This time the mechanical hand pulls on the hammer handle while the tip of the claw clutches a steel bolt. As the bolt is embedded in a steel plate and cannot let go, the hammer han- dle breaks. The amount of load the handle will withstand before breaking is accurately registered and must meet a certain predetermined point if the hammer is to be ap- proved by the Popular Science Institute. The two men in the photo above to the right are testing the spindle of POPULAR SCIENCE MONTHLY Marcu, 1930 . Testing Tools in the Laboratory By COLLINS P. BLISS Director, Popular Science Institute ey kee a We Pig ae ee in tain he Bl Be ge Testing the spindle of a lathe for parallelism in the laboratory of the Popular Science Institute. Forty different points of inspection are covered in the testing of an ordinary screw cutting type of lathe. a lathe for parallelism. In all, there are some forty points of inspection on the ordinary screw cutting lathe, while a still greater number must be checked in the case of lathes with special attachments and accessories. Several testing bars— like the one shown in the headstock of the The strength of the claws of a hammer is recorded on the dial of this testing machine, which can exert tremendous force. lathe illustrated—are used in this partic- ular testing process. The degree of hardness of the steel is an important point to be considered in the case of most tools, and the scleroscope, shown in the circle at the top of the page, definitely establishes this point. At the time the picture was taken, a pair of pliers was being tested. In testing, the cutting edge is clamped to the anvil of the machine by the revolving wheel at the left. A diamond pointed plunger released by the operator registers on the dial the intensity of the blow. This is a measure of the hardness of the material. In the case shown, the scleroscope num- ber was eighty—which is a very excellent figure. HE tests described here give an idea of how Popular Science Institute finds out the essential facts regarding a tool before reaching a decision as to its merit. When the approval of Popular Science Institute has finally been granted to any tool, it means that it is well made of proper materials, represents good value, and is capable of giving satisfactory and lasting service. Full reliance, therefore, may be placed on tools advertised in POPULAR SCIENCE MONTHLY, all of which carry the Institute seal of approval. * * Readers may obtain a complete list of all tools that have passed the tests by apply- ing to Popular Science Institute, 381 Fourth Ave., New York, N. Y. MARCH je 9 -

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1939 Marcu, 1930 ee | l Gi Jo mc i880 For sturdy incubators hatch ’em—raise ’em-—sell ’em POPULAR SCIENCE MONTHLY Pie, Sagas For easily cleaned floors in poultry houses They 13 For signs and cut-outs with PRESD WOOD In Racine, Wisconsin, a big manufacturer of incubators finds that Masonite Presdwood gives his product great strength, withstands moisture, is naturally attractive in appearance, and requires no paint for protection. On a issouri farm, an expert poultry raiser uses this same oo wood on hen house floors and under roosts, ecause of its smooth sanitary sur- without splitting. Always the same in ier and den- sity, Presdwood adds quality and dependability to manu- factured items. Makes manufacturing more profitable, too, because of the way this grainless wood cuts down costly rejections in final inspection. Contractors, handling concrete work, use Presdwood to line the forms because of the thou- face which is so easily cleaned. sands of dollars it saves. Its lighter Withstands the weather In Kalamazoo, a sign manufacturer makes attractive cut-outs which advertise baby chicks, and finds Presdwood ideal for his purpose. It does not crack, split or splinter; is easily cut to shape. It withstands the Masonite Structural Insulation Presdwood’s companion product, Masonite Structural Insulation, was used in the walls and roof of the hen house above illustrated. It was used to save fuel, to reduce the feed needed in the generation of body heat, to keep the hens warm and healthy in order that egg production might be kept at a maximum during the winter. weight cuts down drayage costs. Its workability reduces the time of mak- ing, erecting and wrecking the forms. Its perfect smooth surface eliminates all grain and knot marks, and pro- ducesa superior surface that requires no hand smoothing except at con- struction joints. weather, takes any finish readily, and The Presdwocd booklet is Free does not warp when properly handled. And so it goes in hundreds of industries and in thou- sands of home workshops where Presdwood has been adopted because of its many advantages. Factory experts, operating punch presses, milling ma- chines or band saws, like Presdwood for its workability. It is strong and dense, yet easily cut. It can be worked with knife or chisel or saw, and can be nailed near the edge MASONITE CORPORATION, Dept. D-3 111 W. Washington St., Chicago, IIL. | Please send me, Free, a sample of Masonite Presdwood and the Presdwood booklet. | Name.............- ’ = | Address State saienaneenaeensidideanianaaaae I No wonder builders, home owners and manufacturers everywhere are turning to Presdwood. The complete story of this grainless wood, with illustrations ofits uses, isin ws heel as booklet which is sent Free on request. Your copy will be mailed promptly on receipt of the coupon. MASONITE CORPORATION 111 West Washington Street Chicago, Illinois asonite PRESDWOOD

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From a Famous Engineer SHOULD like to call your attention to an article in your publication for January, 1930, pages 17 and 129. This article refers to “street noises,” and dismisses the most serious street noise with some remarks that are not correct. I refer to the noise of riveting machines, in steel buildings. Your article states that it will be premature to do anything regarding this, and that in time it may be replaced by welding. I do not agree with either one of these statements; and as a structural engineer who has had both bridges and buildings in charge, I would say that to correct this noise would be rather an easy matter. Riveting can very well be done by pressure instead of percussion machines. An oe oe A riveting machine can be installed at a very slightly increased cost, as well as air machines, run by compressed air without a percussion effect. Such machines are being used constantly in shops where bridge and other steel members are being manufactured, and there is no rea- son whatever why they could not be used in buildings, except for their slightly increased weight, and for the fact that in some cases special machines might have to be made. This latter objection, however, might in a great measure be removed by care in design of the structure, so that such machines could be applied. Very truly yours, Ralph Modjeski, New York, N. Y. Ralph Modjeski is one of America’s foremost bridge engineers. He is best known for his work as chief engineer of the great Philadel phia- Camden bridge across the Delaware River, and as one of the engineers who built the famous Quebec cantilever bridge across the St. Lawrence River. A Ventriloquist, Maybe ] ENJOYED Martin Bunn’s article, “What Horsepower Really Is,” but I am puzzled to know how Gus, the auto sharp, managed to talk con- tinuously and eat his lunch at the same time. At the beginning Gus is described as having “his mouth too full of ham sandwich for articulate expression”; yet he never stops talking and we find him at the end “sweeping the crumbs off the table into his lunch kit,” which indicates that the lunch actually was consumed while he discoursed so learnedly on measuring mechan- ical power. Even if he could do it, so wise a man should know better. Certainly his mother taught him that it’s not nice to talk with your mouth full of food.—P.M.O’H., Wil- mington, Del. Saved His Life OMING June will mark three years since I ° went to a hospital, from which I was not expected to come out alive, but I pulled through in time and while convalescing started to make a Spanish galleon. That work really saved my life as it kept me occupied and I forgot all about my misery. I never will be able to follow my former occupation, but dur- ing all my time at home I became very well acquainted with Captain McCann’s ideas and his skill as a sailor. I have built all the ship models you published the plans for, with the exception of the “Constitution” and sold four of them. I am nearly sixty years old and I be- POPULAR SCIENCE MONTHLY lieve there are more men of my caliber—a little lazy in writing letters, but, nevertheless enjoying your articles tremendously.—J.K., Stapleton, N. Y. That Automobile Speed WELL I certainly was surprised when I sat down to work out your little problem about finding the average speed of an auto- mobile that traveled one lap at ten miles an hour and the second at fifty. I’d have said “thirty” right off if I hadn’t been told that Ww. was wrong. Here’s how I did it. I supposed the track was fifty miles long. Then it would take the auto driver five hours to cover the first lap and one hour to cover the second. Total, six hours. Total distance (two laps), 100 miles. Average speed, 100 divided by six. Answer, 1624 miles an hour average speed. Sounds. unbelievable, doesn’t it? I tried it again with another distance, but it doesn’t matter; you could call it X and solve it by algebra. The trick is simply that the problem gave distance—“one lap”— instead of time. If an auto traveled for one hour at ten miles an hour, and another hour at fifty, of course the average would be thirty. And, by the way, that little problem cer- tainly shows how a bit of bad road will cut down your average speed when you go touring. —F.B.H., Cambridge, Mass. Chemistry vs. Physics N YOUR interesting survey of “What Science Achieved in 1929” I seem to sense a battle brewing’ between the cohorts of chemistry on one hand, and those of physics on the other. Thus, in reviewing the progress of chemistry during the year in your magazine, Dr. Hugh S. Taylor, Professor of Chemistry in Princeton University, says: , “The discovery by Giauque, Johnson, Birge, and King of two hitherto unsuspected isotopic forms of the elements oxygen and carbon, by an analysis of their spectra, constitutes another notable advance.” And in the very same column, under the head- ing “Physics,” appears this from Dr. Paul R. Heyl, Physicist of the United States Bureau of Standards: “In atomic physics there have been dis- covered two new modi- fications or isotopes of oxygen and one of car- bon. These discoveries are claimed by physics, as they were made by physical methods.” Sounds almost like two heavyweight pugi- lists squabbling over the right to the world: title. _Here is just another instance of how modern discoveries of universal forces are tearing down the fences that once divided so neatly the Marcu, 1939 various fields of scientific research. I have just read a statement of Dr. Irving Langmuir, famous chemist of the General Electric Com- pany, that is right to the point. “Physics and chemistry are being inevitably drawn closer together,” says he. “Unfor- tunately, although theoretical physics and chemistry are... being merged into a new science, there are remarkably few men as yet that have received adequate training in both sciences.” It seems to me that the sooner other big men of these sciences quit disputing boundary lines that no longer exist, and instead devote themselves to this broader training, the better it will be for progress. What do other readers think?—J.L.K., Philadelphia, Pa. We Pass the Test Sx months ago I set out to find the most interesting, modern, and authoritative science magazine published and therefore -I had delivered to me 17 different magazines per month. After this six months’ trial, during which period I studied every copy and took note of their articles, illustrations, advertise- ments, set-out, printing, and paper, I came to the conclusion that P.S.M. was well ahead of them all. When I tell you that I had copies of America’s and England’s foremost scientific magazines, I think that this fact stands for itself —J.L.A.R., Hinaidi, Iraq. All Ready for the Great Kite Flying Controversy I NOTICED your article concerning a world’s record for kite flying. This unofficial record was said to be twenty-two hours and twenty-one minutes. I hate to argue about such a small matter, but when a world’s record is thrown in it is a different thing. I have many witnesses to prove that on Friday, February 18, 1907, Tom Moran and myself, while at boarding school, put up a kite at eight o’clock in the morning, and it stayed up until Sunday night at six-thirty. I think if you figure that up it will come out at fifty-eight and one half hours. At that time no other man, airplane, or kite had stayed up more than fifty-two hours. At that time we did most anything with a kite, from ordinary kite flying to fighting with other kites. I wish you would look info this and see if we are any ways near a world’s record, although I believe other kites have stayed up longer.—T.A.D., Detroit, Mich. Meteoric Matrimony [Ast night I was sitting at my desk reading your little book, “The Pocket Guide to Science.” In the chapter on the “Story of the Stars” I read this: “‘ Do We Need to Be Afraid of Falling Stars?”, and the following discussion: “No. The chance of one hitting anybody is less than one chance in a great many billions. There MaRCcH,

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1930 st ve er rk 1e ic r sw ee ee eee we MaRcH, 1930 There is New Mechanical Lucellence in this finer Fontiac NEW SERIES a. has always been held in high favor by motorists interested in mechanical details. This is especially true of the newest Pontiac—the New Series Pontiac Big Six. For, in addition to offering all of the features of big car mechanical excellence which character- ized its predecessors, this finer Pontiac offers many important improvements. There is the increased smoothness of its 60-horsepower, L-head engine —the result of new-type rubber engine mount- ings which insulate the engine from the frame. Its big, dependable, internal four- wheel brakes have been made still more effective. A new steering system, which acts on roller bearings, contributes added POPULAR SCIENCE MONTHLY handling ease. A more efficient type of starting - motor, semi-automatic and manually controlled prevents chipping of the fly wheel gear teeth. The lateral rigidity of the crankcase has been strengthened to reduce crankshaft dis- tortion to 2 minimum. And so on all through its chassis you find similar examples of improved design. But don’t be satisfied just to read this brief statement of what the newest Pontiac offers. Go and see the car today. Arrange for a real test out on the road. That is when you will learn why we call the New Series Pontiac Big Six “a finer car with a famous name. Oakland Motor Car Co., Pontiac, Michigan Write for an interesting booklet which illustrates and describes the design of the New Series Pontiac Big Six PRODUCT F PONTIA GENERAL MOTOR S 15 BIG S 1X

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16 is no record of any one ever having been hit.” As I Jaid aside the little book and picked up the daily paper to scan it, the first thing that caught my eye was this heading: METEOR KILLS TWO AT WEDDING PARTY. Accordingly, under the chapter on falling stars in the pocket guide I suggest a revision of the query and answer to the following: “Do We Need to Be Afraid of Falling Stars? Only in the Case of Matrimony!”—E.A.T., Columbia, Tenn. —And the Good Old Ashes wr not get a man who is an authority on anthracite coal to write you an article on coal as a fuel? I’ve read the article on oil as fuel, by Mr. Bliss. In one place he tells you oil users would pay 100 percent more for oil be- fore they would go back to coal. Does he know that recently a man from the New England states said that he would never use oil if he could obtain a steady supply of good old anthracite? With the assurance of no strikes in the future, and a steady supply of coal, there will never be the time when oil will scrap the coal shovel. Me for anthracite, the good old clean, safe, silent fuel.— S.B.M., W, Pittston, Pa. The Cat Walk—It’s a Gift PERHAPS some of your readers who are interested in “heredity” of humans (and cats) may be interested in the following. We had a black female cat who, when hungry, would run alongside of those she knew, running on three legs, and tapping the foot of the person she was following with one of her forepaws. One of her kittens, a black tomcat, now about a year old, does the same thing. As the old cat died when this cat was a very small kitten, it can hardly be attributed to imitation, and must apparently have been “handed down” in the brain cells as a char- acteristic. 1 have never seen any other cat do the same thing, that is to say, any full grown cat.—C.L.W., Sykesville, Md. Meeting Human Needs F YOU ask me, the best thing in your January number was a little picture on page seventy-three, showing an apparatus that meets the well-known “long-felt need.” A device permitting a man to breakfast and read in bed in comfort is something I have vainly sought for many years, each of which included fifty-two Sunday mornings marred by its lack. The word “man” is used advisedly. In your WAITAH | _ presentation of the nov- elty you made two mis- takes. First, it was poor policy to show a girl using it, for if women are encouraged to eat and read in bed, who will cook the Sunday breakfast? Secondly, you spoiled things somewhat by emphasizing the gadget’s usefulness in the sickroom. Doubtless it will prove a boon to invalids, but the thought will not down that there was some- thing Puritanical about this insistence and that you cling to the deplorable notion that leisure and comfort interfere with the soul’s salvation.—P.E.F., Philadelphia, Pa. ERY W/ One from Australia KACB fresh number of your magazine is eagerly anticipated and I ampleased tosay that I have never rienced disappointment with any of them.—-B.B.L., Sydney, Aus. POPULAR SCIENCE MONTHLY A Hero to Our Rescue “T DO not like any of the articles that you publish in your magazine. If you do not leave everything out I will quit taking it. Confine your magazine to the two covers and the advertisements, and you will publish a magazine that is worth read- ing.” Now wait a minute, Mr. Editor. That is not my senti- ment at all. But if you com- bine the substance of all the “kick” letters that you receive, is not the above the sum of their complaint? Some say “leave this out”; others want “that left out.” Some say “there are plenty of other magazines to publish this and that.” Of course there are. But is that any.reason why it should not be published in P.S.M.? Perhaps some of us do not take those other magazines, and then we would miss a lot of mighty good reading. Of course there are some things in your magazine in which I am not interested. But I am not asking you to leave them out. Some one is interested in them, or they would not be there. It would be just as foolish for me to go to my grocer and say, “I will stop trading with you if you do not stop selling peas; I do not eat them, because they roll off my knife.” But other people eat them, and so the grocer keeps on selling them, and tells me to get a shovel. You, as an editor, know what to put in your magazine. Almost anything interesting appeals to the intelligent reader. As for some articles not being scientific, there is no such thing. Aviation, motoring, model building, polar exploration, fossil hunting, fire prevention— there is nothing today that is not based on science. So keep your fine magazine going as in the past, and tell the whiners to go to—Wash- ington.—E.B.M., Bakersfield, Calif. Is He Right? JN DEFENSE of your writer, whom R.A.L. challenges: The writer is very conservative when he states that two thirds of the lift of a plane’s wing is obtained by the vacuum on top. Some experts say that it’s three fourths of the total lift. As to Mr. L.’s statement that if this is so the plane flying upside down should fall, there is this to be said: When flying upside down the plane is slightly tilted, the nose high, thus increasing the degree at which the wings strike the air (the angle of incidence). As this is increased until it reaches about sixteen degrees, the lift also increases. This angle forms a vacuum on top and destroys the one on the bottom which the camber (curve) tends to make.—L.B.S.,-West Hartford, Conn. Profit in “Fixing It” [VE read PopuLar ScrENCE MOonrTuHLy for many years, beginning in 1916 or 1917. Then I used to buy them at the news stands but lost out on so many numbers that I am a sub- scriber now. I have made many articles I found in P.S.M. and am very well pleased with them. Your “Fix It Yourself” book and the “Pocket Guide to Science” are wonderful. The “Fix It” has saved me the price of PoPULAR SCIENCE MONTHLY many times this summer on the house and furniture. I like the Home Workshop section of your magazine the best, but would like more articles relating to repairs in and around the home, toys, etc., for I have not the time to make the ship models. However, I am only Marcu, 1930 one of your readers and you have to please thousands, so if I do not get what I want I shall not complain.—I.C.E., Asbury, Mo. Going One Better I AM well pleased with P.S.M., expecially with the article “Solo Flying for Young Aviators,” by Charles A. King, in the January issue. But I went a little further than he did and mounted a small electric motor in the plane, and had this controlled by a small transformer which in turn was connected toa “throttle.” With this arrangement you can control the speed of the motor. Maybe some other air-minded readers would care to try this.—R.M., Center, N.D. Some Simply Don’t Answer PAR be it from me to join M.O.R. in decry- ing scientific progress, but I confess I was dismayed by the news that the Leviathan had installed a regular ship-to-shore telephone service for its passengers. Nautical news- papers and radio com- munication we have had for some time, and lately Cay full-fledged brokers’ offices made their ap- pearance aboard ocean liners. And now the telephone furnishes the last link with land. And such a link! One of the chief charms of a sea voyage to me has always been the cer- tainty that I couldn’t be “wanted on the phone.”’ Pretty soon this will be a thing of the past, for the other liners are sure to follow the Leviathan’s example. Then where is a business man to go who wants to get away from the manifestations of our hectic existence? What do you suggest—Mount Everest? —L.N.McB., Boston, Mass. In a Nutshell E B.R. surely speaks a huge mouthful of ¢ truth, when he says we’re all one huge family. I am just another of the Huge Family that enjoys the PopuLar ScireNcE.—J.J.N., Pasco, Wash. Paus sure can paint good pictures. Here’s hoping he may paint many more of your covers.—A.L.R., Watertown, Wis. I think P.S.M. is the best of all scientific publications. By all means keep up the Home Workshop and Back of the Month’s News. —J.D.F., Carlisle, Penn. I thoroughly enjoyed the article on psy- chology in the December number. Let’s have more of them.—G.V.H., Springfield, Ill. PopuLAR SCIENCE MonrtHLY has kept me up to date on science and inventions, which I must say hold my interest. I hope that your magazine for the coming year will be as inter- esting as it has during the past year.—L. van M., Forest Hills, N. Y. And the Soup Inhaler? EW YORK’S anti- ~ én noise campaign, so vividly described by E. E. Free, is one of the most urgently needed civic crusades ever to come to my notice. The arrogantly barking auto horn, the nerve-wrack- ing riveting machine, the rumbling truck, the grinding trolley car, and che bellowing street loudspeaker must be muted. This accom- plished, the committee might concentrate on muzzling the talker, candy-unwrapper and program-rustler in-the theater; the drink-and- tell-all antiprohibitionist; the travel-broad- ened returned European tourist; the surgical operation survivor, and the stock market winner and loser.—B.A., N.Y.C. MARCH ee gat Ke ch ha pre at

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Marcu, 1930 POPULAR SCIENCE MONTHLY

COOLS while you shave and the cool- ness lingers! LISTERINE SHAVING CREAM “That sore throat’ll be gone by morning” ORE throat is a warning to look out for a a which are caused by germs breeding in cold—or worse. i the mouth. If you have the slightest indication of trouble, sae Though Listerine is powerful you may argle immediately with full strength Listerine. — use it full strength, with entire safety, in gargic y & “ § ; Keep it up. | any cavity of the body. Indeed, it is Millions have found that this simple act ie actually soothing and healing to tissue. checks the ordinary kind of sore throat promptly. This is commented on by the famous y . . y . y . Keeps it from becoming serious. Moreover, the **Lancet,’’ the leading medical publica- : oe Id have proved that its systematic use is excellent +9 ©SCAPE 4 COLE tion of the world. protection against having colds and sore throat | the hands with it Keep a bottle of Listerine handy in Colds can often be prevented by the < at all. use of full strength Listerine onthe ~home and office and use it frequently — . . ° ands before each meal, it destroys e When you realize that full strength Listerine germs which may be present, so that especially after exposure to cold weather . . ° when they enter the mouth on ° . . kills even the virulent Bacillus Typhosus (ty- they are powerless to cause harm. of germ-catrying crowds in offices, rail- phoid) and Staphylococcus Aureus (pus) germs in num- _—-way trains, street cars or buses. It may spare you a bers ranging to 200,000,000 in 15 seconds, you can under- _—s trying and costly siege of illness. Lambert Pharmacal stand why it is so effective against cold weather complaints | Company, St. Louis. Missouri. LISTERINE ™: sare axrisepric kills 200,000,000 germs in 15 seconds

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18 POPULAR SCIENCE MONTHLY Celotex Lath, used as a base for the handsome plas- tered surfaces of this room, protects their beauty from disfiguring plaster cracks and lath marks. ou protect the § beauty of plastered walls with Celotex Lath # : 4 - ...and make sure of pleasant even temperatures in every room all year ’round ISE home owners already that not only guards your home against know the urgent need for insu- lation in modern homes ...understand how Celotex shuts out the cold and dampness of winter as well as the heat from summer sun. all extremes of temperature but also provides (lasting protection to the beauty of your walls and ceilings. Celotex Lath comes in units meas- uring 18 inches by 4 feet. The size of the units and their overlapping joints prevent the streaky appearance and unsightly plaster cracks that so often occur with old-fashioned lath. Now home owners have learned about Celotex Lath... the plaster base As insulation, Celotex Lath adds very little to your building costs ... it simply takes the place of ordinary lath. And in years to come it saves you hun- dreds of dollars in fuel bills by prevent- ing costly leakage of furnace heat. Your architect, dealer or builder will be glad to explain how Celotex Lath IDEAL FOR REPAIRING AND REMODELING Attics lined with Celotex Lath transform wasted space into pleasant, livable rooms. wane The rigid units are light and easy to apply. CELOTEX Where attic space is limited, you can hep (Reg. U. 8. Pat. Off.) the whole house more comfortable by nail- ee ing Celotex Lath to the attic floor joists and ba ong sad stopping the costly leakage of furnace heat. — Marcu, 1930 can be used in building your new home . .or in making the home you live in now more enjoyable the year ’round. Get in touch with him at your first opportunity. And write for our interesting new booklet, “Celotex Cane Fibre Insula- tion,” telling how Celotex provides greater comfort and lower fuel bills. The Celotex Company, 919 North Michigan Avenue, Chicago, Illinois. In Canada: Alexander Murray & Co., Ltd., Montreal. (Member of the Home Modernizing Bureau of the National Building Industries, Inc.) Sales distrib- utors throughout the world. Reliable dealers can supply you with Celotex Standard Building Board and Celotex Lath. CELOTEX | BRAND INSULATING CANE BOARD LATH N operat In on all af Assoc turnir Calife a was | conce plane parts the fi Glidi: come In ing h from ness 1928, from boys At a in tl com] birds silen whet circl Cod.

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MONTHLY TRAVIS HOKE Editor VOL. 116, NO. 3. ——i > ORE than a thousand Americans are flying without motors. Thirty-two gliding clubs, scat- tered from coast to coast, are in operation and fifty more are being formed. In one state, Ohio, there are nine clubs, all affiliated with the National Glider Association. A dozen companies are turning out motorless craft for sale. The California factory where The Spirit of St. Louis, Lindbergh’s famous plane, was built has just been taken over by a concern which plans to turn out soaring planes in mass production. In several parts of the country, schools are teaching the fine points of riding the air currents. Gliding—older than the airplane—has come into its own. In Germany, for instance, where glid- ing had its start, 200,000 people, ranging from school children to middle-aged busi- ness men, have joined gliding clubs. In 1928, more than 10,000 flights were made from German hillsides and 3,000 school- boys were instructed in handling gliders. At an intérnational motorless plane meet in the Rhoen Mountains last year, 105 competitors spiraled and swooped like birds. In faet, so birdlike are these silent, wide-winged, soaring ships that when Peter Hesselbach, two years ago, circled over the headland and sea at Cape Cod, Mass., for more than four hours, a os - eid =. * * ae Oe 95 4 ee S Ff eas wae” Snapped into the air by elastic cable—the launching of a glider at Los Angeles, Calif. Thousands Are Flying Gliders Within the year the sport of gliding has advanced to a point where it is safe, easy to learn, and useful. More than a thousand American men and women, girls and boys, now are following it with enthusiasm. Other thousands are preparing to try their wings. Here is the first of a series of articles explaining all the facts about this thrilling outdoor sport which is training the aviators of the future. By . EDWIN W. TEALE dozen gulls came in from the ocean and fell in behind, following the strange machine fearlessly for a quarter of an hour at a time. The value of gliding as a training for powered flight is fully recognized. Ger- man transport lines require glider licenses of their pilots. In America, the Curtiss- Wright Flying Service, controlling forty fields and operating schools in all parts of the country, plans to build gliders and to instruct students in their use. Famous pilots, as well as beginners, are enthu- siastic over the sport of motorless flight. Charles A. Lindbergh, Amelia Earhart, Frank M. Hawks, and “Eddie” Stinson are among the many noted flyers who have recently climbed into the air on motorless planes. A beginner on a glider is not disturbed by the speed, roar, vibration, and fumes of a motor. There is no throttle to regu- late. He can concentrate upon maintain- ing balance, getting “the feel of the air.” This saves time later during powered instruetion. Reduced tuition is offered by some German aviation schools to expert glider operators. Boys, too young to learn to fly, take up gliding as a link between models and powered planes. They get into the air cheaply and safely. Properly conducted, gliding entails a minimum of risk. There is no fuel tank and consequently no fire hazard in a rough landing. Instead of making con- tact with the ground at express-train speed, as in an airplane, a glider drifts to a landing against the wind at a few miles an hour. Early flights in primary gliders are made only ten or twelve feet from the ground. Last summer, 800 flights were made at 19

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POPULAR SCIENCE MONTHLY Above: William Atwood riding his glider above a hillside at San Diego, Calif. He reached an alti- tude of 200 feet. Right: Baron Freyberg-Harth, German glider, flying a birdlike soaring plane in which he remained in the air more than two hours. Cape Cod and not a student was hurt. In one week at the University of Michigan 125 people safely hopped off a long hill- side, and seven of the pilots were girls. One German glider has carried 5,000 people aloft without an accident. O UNDERSTAND the fascination of literally riding on the wings of the wind, consider the thrills and the unex- pected in a single soaring adventure of the German pilot, Wolfram Hirth. Lifted from a mountain side by an updraft, he soared into a low cloud bank. For minutes he flew, silent as a ghost, through envelop- ing mist. Then, losing altitude, he drifted down out of the clouds above a mountain meadow. Boys, herding cows, ran to see him land. But just as the tail skid was swishing through the long grass, an unexpected upcurrent poured through a small gap in the mountain, carried him a hundred feet in the air, and enabled him to glide over the hills to the valley beyond. For more than half an hour he soared about, taking advantage of every rising current, following a railroad that crept up the valley, winging his way over forests, villages, and rivers. At Steinach, the inhabitants rushed into the streets to stare up at the giant bird sailing over- head. Swinging back and forth above the ruined Steinach Castle, Hirth then rode an updraft hundreds of feet into the air and sailed over the next range of hills to the broad Saale Valley. As he passed over the railway depot of the resort town of Kissingen, he played ‘‘air ghost.” Leaning over the side of the cockpit, he shouted: ‘‘Hello there!” startling the people standing on the platform waiting for their train. Beyond the town, two mountains came together at an acute angle. A north wind blowing into the corner made a trap for the soaring plane. It lost altitude. Again the tail skid almost touched the grass, when another unexpected gust carried the glider aloft and Hirth guided it above the mountain saddle. In the next valley the flight ended. As he was losing alti- tude, Hirth saw a motorist on a lonely road. He circled the machine and then drifted down to a landing in a meadow a few yards from the road. The autoist took him to town and-he notified his friends of his whereabouts. By similarly jockeying motorless ships to take advantage of rising air currents, an American pilot, W. H. Bowlus, a few weeks ago, soared over Point Loma, Calif., for an American duration record of five hours and twenty-seven minutes, and a German soaring ace, Hermann Dinort, swung back and forth above the sand dunes on the Baltic seacoast for fourteen hours and forty-four minutes, setting a world record. During this long motorless flight, Dinort weathered a fifty-mile gale and flew most of the time through darkness. How is it possible for a machine weighing several. hundred pounds to hang in the sky from morning until night without using a motor? Two factors enter into an explanation of this seeming miracle. Marcu, 1939 In the first place, soaring planes are per- fectly streamlined. They are built of the lightest material, so that the loading per square foot of wing surface is low. Conse- quently, many soaring machines have a gliding range three times that of the ordi- nary airplane. They advance twenty feet for every one they descend. This enables them to travel long distances from mod- erate heights. The second factor in motorless flight is found in rising air cur- rents. When a wind strikes the side of a range of hills, for example, it is deflected upward and forms a rising current. In such a column of rising air, the soaring plane gains altitude, being carried upward faster than it descends. The pilot guides it from one rising current to another, the height lost in gliding between air columns being regained in passing through them. For soaring, hills and preferably ridges facing prevailing winds are required. OW slight an upcurrent will some- times keep a light soaring ship in the air was demonstrated recently in Ohio. The “Akron-Condor” soarer, with W. Klemperer, the famous sail plane pilot, formerly of Germany, at the controls, was being towed from Akron to Cleve- land by one of the Goodyear blimps. Near Wallings Corner, the towrope parted while the glider was 700 feet up. In spite of its low altitude, it sailed for five miles and landed in a large field. The pilot had difficulty in landing because the heat currents rising from the ground caused the soarer to float nearly the entire length of the field at an altitude of only a few feet. Between soaring and glid- ing there is a sharp line of distinction. In soaring, the machine rises on upward air currents higher than its start- ing point. In gliding, it descends from a higher to a lower place, “sliding downhill” on the airea few feet above the ground much as a sled coasts over the snow. The first step in learning to soar is simpie gliding. Primary training gliders, heavier and less efficiently streamlined than soaring ships, are used. A dozen men, running into the wind at the ends of a long rubber cable while others hold back the machine, launch the primary glider as well as the soarer. When the cable is stretched the men at the tail release the glider, which shoots into the air and sails to the bottom of the slope. During the glide, the machine is governed by a regulation stick and rudder bar control. Advanced pilots often go aloft towed by automobiles or airplanes, cut- ting loose when sufficient altitude has been gained. A hop of thirty seconds straight down a hillside earns for the pilot a third-class glider pilot’s license and the one-star insignia of the National Glider Asso- ciation. A one-minute hop with a com- plete right, left, or “S” turn entitles the pilot to a second-class license and a Next month: “How to Get into the Gliding Game.” Another inter- esting article giving facts that every- one interested in this thrilling new sport will want to know. Marc doub five “gives covet ican Bowl Barn cond gers at La 1; fi glide delic. In tl be t macl pens to a and Thu: at th and | glidi stud hour scho the Asso easic “ker secti try. mov gars abot plac tion old- ous whi dan and by fron rece Assi I mac nee thei a Sj In | tur fact ‘sail pro Fre Cs

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930 er- the per se- Cc a ‘di- eet les »d- ur- fa In ng les he ns es Marcu, 1930 double-star insignia. A soaring flight of five minutes above the starting point ‘gives him a first-class license and the coveted three-star insignia. Three Amer- ican pilots hold first-class licenses, W. H. Bowlus, W. Klemperer, and Lieut. R. S. Barnaby, U. S. N. The latter plans to conduct experiments in landing passen- gers from the dirigible Los Angeles at Lakehurst, N. J., by means of gliders. HE cost of motorless planes ranges from about $435 for primary training gliders to several thousand dollars for delicate, record-breaking soaring ships. In this country the usual plan seems to be to organize a club and buy a primary machine, the members sharing the ex- pense. One member is then chosen to go to a glider school for expert instruction and on his return he teaches the others. Thus, the individual cost is kept down, at the same time providing safe machines and competent instruction, without which gliding should not be attempted. Many students are able to fly gliders after one hour of instruction. A mobile gliding school is planned by the National Glider Association to make easier the training of “key men” in different \\ sections of the coun- try. This school would move its planes, han- gars, and instructors about from place to place, giving instruc- tion. The use of the old-fashioned, danger- ous “hang” glider, in which the operator dangles from arm rests and preserves balance by swinging his legs from side to side, is not recommended by the Association. It was upon such machines that the pio- neers of thirty and more years ago made their first flights. For gliding is more than a sport. It gave the world the airplane. In the latter part of the nineteenth cen- tury four men—a retired German manu- facturer, Otto Lilienthal; an English sailor, Percy Pilcher; a California college professor, John J. Montgomery; and a French-American bridge builder, Octave os A POPULAR SCIENCE MONTHLY kets — Bes bos tes ee These girls are receiving instructions in piloting motorless planes at the first women’s glider school established near Berlin, Germany. Chanute—blazed the trail with motorless machines to the conquest of the air by the Wright brothers. When the airplane appeared, gliding languished. All attention was directed to powered flight. In 1911, Orville Wright took an English friend to the Kitty Hawk dunes and made some gliding flights for fun. On one he hovered for nine minutes One horsepower hauls the glider plane to the top of a hill for the take-off. It’s a long way up, but great sport to ride the air coming down. A scene during a recent motoriess plane contest. 21 At the moment of launching. The men in the foreground have run down hill, pulling the motorless plane by a cable, into the wind. and forty-nine seconds in a gale. So slight was the activity then in gliding that for ten years that record stood unchallenged. Following the war, the restrictions put upon German aircraft by the Versailles Treaty turned attention in that country toward motorless machines. In the Rhoen Mountains of central Ger- many and among the dunes of the Baltic coast, the soaring ships hung in the air for longer and longer periods. The records culminated in Dinort’s recent flight of nearly fifteen hours. In America, gliding has taken a new hold in the last two years. The soaring flights at Cape Cod, in the Alleghenies, and on the Pacific Coast have attracted fresh attention to the sport which Mont- gomery, Chanute, and the Wrights em- ployed to learn the secret of flight three decades ago. Last year, motorless fiying meets were held at Detroit, Mich.; Cleve- land and Lima, Ohio; and Los Angeles, Calif. The first International glider air mail was delivered recently when Oscar Kuhn, a pilot for Gliders, Inc., of Detroit, made a towed flight over the border to Windsor, Canada, and soared down to the airport to deliver a packet of letters. HE only official American glider record, at this writing, is the five-hour- and-twenty-seven-minute duration flight of W. H. Bowlus. To be official, a record must be observed by three timers or judges authorized by the National Glider Association. The present unofficial rec- ords are: distance fifteen and three quarter miles, set in the Alleghenies in 1929 by W. Klemperer; altitude, 600 feet, also set by W. Klemperer in 1929. Seven kinds of glider records are recog- nized by the Association. They are duration, with return to point of depar- ture; duration, without return to point of departure; distance, air line; distance, with return to point of departure; alti- tude above start- (Continued on page 154)

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ne ll Bk i Maw Pygm POPULAR SCIENCE MONTHLY y Tugboats Dock a Giant Liner or sae f ' é ‘ pe vw = “Swinging the huge liner broadside to the current is like forcing a dam forty feet deep and 900 feet long upstream. Against a mountain of water the tugs pit their strength.”’ By ROBERT E. MARTIN SHEER eighty-foot cliff of steel rising straight into the air. Small white faces peering down from the rim. A pygmy figure, wearing an aviator’s helmet as protection from the biting wind, standing on the bridge a hundred feet above the water. Hand- kerchiefs, hats, an orange flag, waving frantic greetings from a dozen round port- holes piercing the metal wall. That was the tug’s-eye view of the Leviathan— America’s greatest liner—which I ob- tained the other day when I rode up the North River from New York Bay to see first-hand how a liner is docked. Captain Allan Howell, of the tug Dalzellea, had picked me up at the Battery landing where the busy Statue of Liberty boat takes visitors from all over the world to see the famous Bronze Lady. Howell is square shouldered, firm jawed, has a humorous twinkle in his eye. Since 1903 he has been meeting the big ships that come in from the sea—“‘putting the liners to bed.” While the Dalzellea plowed up the North River—as all seamen call the mouth of the Hudson—past steamers, ferries, and barges, he explained some of the difficulties in docking a liner. Big ships can neither start, stop, nor turn quickly enough to enter a slip without the aid of tugs. As everyone knows, the Leviathan is between 900 and 1,000 feet long. Coming into port, it weighs more than 60,000 tons. Yet the problem of swinging the liner around and moving it into its slip would be simple were it not for the com- plicating factors of wind, tide, and ice. One night, a few years ago, a wind swung the Leviathan around just as it approached its slip and jammed the vessel across the ends of the two piers, bottling up the slip. Three tugs were caught inside, the rest outside. Those inside pushed; those outside pulled. The big ship wouldn’t budge. Additional tugs were called. The vessel remained glued in place by the force of the gale. The battle lasted almost all night before the liner was safe in its berth. Anyone who has struggled against a wind with an umbrella will appreciate the force necessary to push back an ocean liner whose side is like a gigantic billboard nearly a thousand feet long and eighty feet high. Once, when the same vessel was being dry- docked in Boston, in spite of the combined efforts of sixteen tugs, a wind swung it out of control, smashing a pier. UT wind is only one of the enemies of a_ successful docking, Captain Howell told me. The direction and strength of the tide, the amount of Marca, 1930 floating ice in the water, the presence of other vessels in the slip—all these influ- ence the maneuvers necessary to bring a liner to its berth. No two dockings are the same. Every one is a battle of wits against a new combination of conditions. At Pier 86, on the Manhattan side, we made fast, waiting for the liner to come up the river under its own power. At Pier 85, in the slip between 85 and 86, lay the Deutschland, the Hamburg-American Line’s huge “bubble ship”—so-called from the bulging lines of its “‘antiroll” construction. Between the Deutschland and Pier 86 was a strip of water a little more than 200 feet wide. Into this strip the Leviathan, with its 100-foot beam, had to enter like a thread approaching a needle’s eye. If it drifted south, it would crash into the Deutschland. If it swung north, it would smash the pier. LONG Pier 86 were five ‘“‘camels”— huge floating fenders placed at regu- lar intervals. These heavy-beamed rec- tangles keep the ship from coming in con- tact with the pier, while allowing gang- planks to reach across. A few years ago, a liner tore away part of its pier when smaller “camels” were substituted with- out warning to the harbor pilot who docked the ship. Two long blasts of a whistle. Two short blasts. The Leviathan was coming. Heading upstream, into the ebb tide, the sea giant came to rest opposite the pier. Eight tugs swarmed around it, falling into predetermined positions. The Dalzellca, with three others, nosed against the hull near the stern on the pier side. It was like stopping below a huge warehouse seven stories high and three city blocks long. “That’s Billy McLaughlin, the har- bor pilot,” said Captain Howell, pointing at the man with the aviator’s helmet on the bridge far above the water. ‘The Captain of the ship is always in com- mand, but McLaughlin, as ‘local guide,’ As the Leviathan turns broadside to the-stream, two for- ward tugs cease straining at the hawsers to push at the bow. Marc! The d “ures by wk a big dire whi: Cap Levi cold

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Marcu, 1930 The drawing below pic- ‘ures the various steps by which the tugs warp a big liner into a dock. DIRECTION a J y PROPELLERS AHEAD PROPELLERS REVERSE D paid TWiST Set directs the tugs. He blows a police whistle to signal them.”” During the war Captain Howell himself docked the Leviathan many times. Once it was so cold the metal of his police whistle stuck POPULAR SCIENCE MONTHLY to his lip, taking off the skin. Afterwards, he used one with a celluloid mouthpiece. For several minutes we waited. “‘It is nearly slack water,” Howell told me. For six hours the tide comes in, then for six Courtesy Fairchild Aerial Survey, Inc. An airplane photograph of the Leviathan nosing into her slip. All of the tugs now are pushing upstream. hours it runs out. Just before the change, there is a period of slack water. This is the easiest time to dock a ship. Government bulletins tell pilots the exact minute to expect high and low tide and slack water. In New York Harbor, the direction of the wind is an important factor in determining the height of the tide. An east wind means a high tide—a strong west wind, a much lower one. Scientists of the Hydrographic Office are helping with more and exact in- formation. One large fleet of tug- boats is soon to be equipped with radio to receive the latest information and instructions. One shrill whistle from the bridge. We look up. McLaughlin has one arm lifted in the air. Begin pushing. The engines of the Dalzellea com- mence throbbing. Two whistles. The figure on the bridge holds up both arms. Full power ahead. The water boils behind the tugs. White lines of beaten foam stream away _ (Continued on page 152)

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POPULAR SCIENCE MONTHLY Marcu, 19309 _—" That Swing 350,000 Tons How great logs are hauled from the north woods by trolleys running on steel cableways. “ HE wire’s got to come down— every strand of it.’””’ The speaker was one of a group of engineers for the new Ambassador Bridge, that was to link Detroit to the border cities of Ontario, Canada. They stood at an anchorage, examining one of the huge cables that supported the 1,850-foot main span, longest in the world. Minute cracks in the silver-bright wire added their testimony to chemical and breaking tests. There was no argument. The wire came down, though two and a half million dollars in labe~ and materials were lost. Sputtering acetylene torches ate away the condemned filaments in great chunks. Every thread was replaced with cold drawn filament of which there was no doubt, and the improved bridge was opened to traffic last November. Engineers who had tried something new on that bridge—a wire heated after it was drawn—had learned a lesson, and so had the scientific world that had watched the crucial experiment in cable-making. Ever since some unnamed German genius, 600 years ago, discovered that cold metal drawn through a hole in a die would make a wire, the art of cable-making has steadily improved. Because of one such advance the forty- seven-year-old Brook- lyn Bridge, in New York, today is safely carrying twice the load for which it was originally designed. The first specifica- tions called for cables of iron wire to support the bridge. Before the spinning of the cables began, How the Strongest Cables in the World Support the Load of Huge Bridges, Carry Aerial Railway Cars, and Serve the Many Needs of Engineers By FREDERICK TISDALE steel wire was perfected. Engineers seized the opportunity to improve the bridge, and in went steel wire. Similarly the new bridge across the Hudson River from New -York to New Jersey, which will be the greatest suspension bridge in the world, is to be stronger than its specifications require. Ways have been discovered to make its cables stronger even since the work began. Not in bridge cables alone does wire rope demonstrate its strength. A locomo- tive made in Philadelphia must be de- livered to a railroad running through the Andes. At tidewater a wire rope sling embraces the engine, while another lifts it and lowers it gently into the hold of the steamer. Similar slings and steel ropes hoist skyward the beams for tall buildings. In mines, workmen and materials descend to the depths on cables of wire, and other cables handle the heavy drills that bore for oil. Modern logging uses the strands to snake the huge trunks through the woods to the rail line. Blocks of granite rise out of quarry pits on wire slings hung from wire rope. Wire makes possible the handling of huge bulks at sea; the drydock Dewey was towed from Chesapeake Bay to the Philippines, Slings of steel rope lift a railway locomotive bodily from a lighter and transfer it safely into the hold of an outgoing steamship. Similar slings hoist the steel beams for skyscrapers. Responding to a hurry call, a welder and his truck speed by cableway across the Mississippi. 13,000 miles, by a pair of steel hawsers. One of the most spectacular applica- tions of the strength of steel rope is in aerial railways that carry passengers and materials in cars slung from ropes high above the ground, to aid in building dams and crossing ravines. When a set of locks was being built not long ago at Lockport, Ill., a welder was needed in a hurry. Answering a telephone call from the other side of the Mississippi River, he decided not to take the time to drive to the near- est bridge. He hooked his auto truck to the cableway that spanned the stream, was hoisted many feet aloft, and, stand- ing atop the swaying truck, made the journey safely on the slender. metal strands. HE length of some of these aerial rail- ways is surprising. A sky tramway twenty-one miles long runs from the mines of the Mejicana district, in Argen- tina, down to the town of Chilecito, carrying coal. On the return trip the cars transport supplies, and other special cars carry inspectors and mail. To reach the two-mile elevation of the upper station the tramway at times ex- ceeds a grade of one to one, and at one point it passes through a mountain tunnel. Colombia has a large tramway of even greater length. In the United States aerial tram- ways play an impor- tant part in the trans- portation scheme. Where railroads can- not run and boats dare not navigate, the cable cars glide MARCH. smooth hour. erally single — treache ore, an four m largest to the Idaho. for a ] ata WwW James shore— the loa uses OU HE con ings ste that it magnif filamer diamor to resis four-th one tw been d: over a is done wires a magnif springs At t monste a cable for an it coul reels. the de that ca tion. machil million haul: Tot a wire machil when factor) heart flexibil made statior guy Ww greate Ac makin right arms base. are b strand They of the the c the st gether Wh are 1 cedurt be us each | circlin reasol tainin five p parall the s other of the On

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wa Marcu, 1930 smoothly along at four to six miles an hour. The monorail cars—for they gen- erally hang on flanged wheels from a single wire—cross mountain gorges and treacherous rivers, carrying lumber, coal, ore, and other products. One cableway, four miles long, carries apples from the. largest irrigated orchard in the country to the nearest railroad, near Weiser, Idaho. Barges with loads of pulpwood for 2 Hopewell, Va., paper mill anchor at a wharf in the middle of the shallow James River rather than risk going in- shore—and an aerial tramway whisks the load ashore. And these are only two uses out of hundreds. HE making of wire for cables has be- come a fine art. By successive draw- ings steel has been reduced to wire so fine that it can hardly be seen without a magnifying glass. In the final stages the filament is drawn through holes bored in diamonds, the only substance hard enough to resist cutting by the metal. Wires one four-thousandth of an inch in diameter, one twelfth as thick as a human hair, have been drawn. Such threads burn like wool over a match. Most of this fine drawing is done as a stunt, though extremely fine wires are used in marking lines of delicate magnifying instruments, or in making springs for small watches. At the other end of the scale are the monster wire ropes. One of the largest, a cable three inches thick manufactured for an iron mine in Cuba, was so stiff that it could not be delivered on reels. It was coiled about the deck of the freighter that carried it to its destina- tion. Hitched to powerful machinery, it draws half a million pounds of ore in one haul: To the maker of steel rope a wire hawser is a piece of machinery. All rope is oiled when it comes from the factory. The core is the heart of the rope and if flexibility is desired it is made of oiled hemp. For stationary ropes such as guy wires a steel core gives greater strength and rigidity. A common form of rope- making machine is an up- right steel cylinder with arms branching from its base. At the end of these are bobbins carrying the strands to make up the rope. They feed into the center of the column which carries the core. The turning of the steel column twists to- gether the strands. When enormous cables for bridges are made, an entirely different pro- cedure is followed. Twisted rope cannot be used here. Strands laid parallel to each other and “spun” together by en- circling wires are employed instead. The reason is that a rope made of strands con- taining fifty wires is only about eighty- five percent as strong as fifty wires laid parallel. When wire is crossed in twisting, the separate filaments rub against each other and thus lower the breaking point of the cable. One of the best examples of modern POPULAR SCIENCE MONTHLY A machine wraps a binding of soft galvanized iron wire around one of the cables of the new Ambassador Bridge across the De- troit River. This nineteen-inch cable contains 8,066 steel wires. cable making was the construction of the cables that will support the new Hudson River Bridge. These cables must be capable of sustaining a dead weight of 350,000 tons, about the weight of six ships of the Leviathan’s size. To do this the four main cables—bundles of straight wire three sixteenths of an inch in diam- eter—are three feet thick each. Bridge wire used for the Hudson span comes from ingots of steel fourteen inches square and five feet long. After careful chemical analysis, selected ingots are reheated and rollers reduce them to Building the cables for the new Hudson River Bridge. Each main cable—a bundle of straight wire—will be three feet thick. sections two inches square. Clipped into thirty-foot billets, these in turn are work- ed smaller. Leaving the rolls, the steel is a round rod similar to a curtain rod, and three eighths of an inch in diameter. That is as far as the rolls can go toward turning steel into wire. EXT comes the die through which the wire is cold-drawn. But the rods are not squeezed through it. Instead, they are tempered, cleaned, and pointed so that an end can be thrust through a hole in the die. A “dog,” a powerful mechanical hand, seizes the small tip and pulls through enough wire to be fastened about a drum. The drum then exerts enough pull to drag the steel through the hole. Passing through four holes each a little smaller than the last, the rod is reduced to wire of the required size. Four thousand feet of wire are drawn from each billet. This drawing of wire through a hole too small for it does not weaken the wire, as might be imagined, but actually strength- ens it. The fibers of metal are drawn into a parallel position which resists any break. Mighty testing machines in the wire factory check up on that. A loud report like that of a cannon means that a wire has finally broken in the testing machine, which can exert forces of as much as two million pounds. One of the single strands of wire used in the Hudson cables would require the. combined pull of ten strong horses to break it. The greatest spinning job the world has ever seen, the (Continued on page 164)

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Dornier’s mammoth DO-X flying boat car- rying 169 persons over Lake Constance. SHORT, shy man stepped from a gangplank the other day on his second visit to America—Dr. Claude Dornier, premier German aircraft builder. He explained his mission simply. ‘‘The aviation of the future is in big flying boats. I think America is the logical place for their development.” On his first visit, in January, 1929, Dornier spoke guardedly of a mammoth seaplane under construction at Lake Con- stance in Switzerland, a ship so enormous that probably no one save himself quite believed in it. By the time of his second arrival in this country his great air boat, the DO-X, had astounded the world by carrying 169 persons into the air. A striking painting of that great craft is shown on our cover this month. The success of the DO-X gives new im- portance to what Dornier has to say about big seaplanes for America. A ship like the DO-X can be used, he says, for an eleven-hour air line between New York City and Miami, Fla. It could link the cities of the Great Lakes region, and take advantage of America’s unique system of inland waterways. Passenger fares for such an air liner need be only half again as much as railroad fares, for travel two or three times as fast. Evidently Dr. Dornier’s statements have impressed American business leaders. A firm to build all sizes of his airplanes in this country—first the smaller ones, then liners of the DO-X type—has been formed by the General Motors Corpora- tion and the Fokker Aircraft Corpora- tion. It has bought his licenses outright. Here is a new figure in American aero- nautics. Though he is reticent in talking about himself, a few minutes’ conversa- tion reveals that he is not only an air- plane designer but also an airship expert and a metallurgist of unusual ability. It was this broad experience that enabled him to crown his career by building an airplane many engineers had branded impossible. 7 HEN the late Count Zeppelin was building dirigibles, in 1914, one of his right-hand men suggested to him that dirigibles might not always have a mo- nopoly of large-scale passenger carrying. The man was Claude Dornier. Dornier pointed out the advantages of huge flying boats. Count Zeppelin told him he would think it over. Shortly after, the Count founded a company to make metal flying boats and put Dornier at the head of it. The factory was at Friedrichshafen. Here POPULAR SCIENCE MONTHLY Dr. Claude Dornier, famous German aircraft builder, who now is planning giant flying boats for American transportation. Dornier’s metallurgical experience served him well. One of his first problems was how to make hulls and seaplane floats of light duralumin alloy that would resist the corrosive action of salt sea water. He found a way to treat the metal, first with electricity and then with lacquer, to make it impregnable. The first of the five types of seaplanes that Dornier built was a little fifty-five- horsepower sport flying boat named the Dornier-Libelle. He has preserved a movie of one of this midget’s first flights. It shows a tiny plane scudding from its lakeside hangar, wings folded back. Then the pilot touches a lever, and without stopping the plane unfurls its wings and takes to the air. Bigger planes followed—the DO-E, a scouting monoplane of the metal flying boat type; the Wal—meaning “whale” — which was a 600-horsepower flying boat, and the Super-Wal, a thirty-passenger - machine. America had its first real glimpse of the Dornier ships only last summer, when the first of a fleet of four Super-Wals for a Great Lakes air line, brought here from Germany, was assembled and flown near Philadelphia. But these planes had been doing regular transport service in nearly every other civilized country of the globe. Marcu, 1939 A New Figure in American Flying By ALDEN P. ARMAGNAC They had carried more than one aerial adventurer safely across the South Atlantic. And Dornier planes held more than forty world records for speed, altitude, and dis- tance with varying loads. All the time Dr. Dornier was evolving plans for a super-liner that could lift more than a hundred pas- sengers. Many engineers called it impossible. He built a plant on the Swiss side of Lake Constance, at Altenrhein. By the end of 1927 he was ready to start work on his dream-ship. It was a new experi- ment in aircraft building. “As flying boats increase in size,” Dr. Dornier ex- plains, “they must be modeled on accepted rules of naval design. It steamship.” Indeed, the ribs, braces, and water- tight bulkhead partitions in the DO-X, as they took shape, resembled those of a seagoing vessel more than an airplane. Just about two years after work started, the DO-X roared across the surface of Lake Constance under her own power. Thou- sands of spectators lined the banks. Among them were aeronautical engineers from France, England, and Italy. And the rumor spread that Dr. Dornier’s great plane was a failure—it couldn’t rise from the water. For three hours the mammoth plane taxied over the lake. Actually the chief pilot, Richard Wagner, was taking no chances. He throttled the engines down, then opened them to nearly full power. He tested every control before risking the lives of the twenty engineers aboard and the structure of the ship which had cost $800,000 to build. At last Wagner moved the controls to lift position and opened the twelve engines to full power. As easily as if she were a bundle of thistle- down, the fifty-ton plane glided into the air. F THE 125 seaplanes that Dr. Dor- nier has built, the DO-X is his chief pride. But while his factory is turning out three more of them—two for Italy and one for Spain—he talks of bigger ships to come. The DO-X is an “experi- mental type.” There is no apparent limit, he says, to the possible size of an airplane. is just like building a steel - MarcH, | Many look a somet on qu But t trance mind beyon hands only 1 reput: Profe: Syrac younges The ma in telep this be proof. sibility the de: verifica Hypr the por ism, an ent mal by the century in term any mM} in it. The: are, to Mesme accept science of “ani the me accom] who m centur: inally | and he notion fate of stellar influen others. Tho

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1930 Gx It or met OD mer Oe ce mh Ss? Se Oe Marcu, 1930 Starting the process of hypnosis by the method of fixed gazing. The subject, seated in a comfort- able chair, looks fixedly at a pencil in the hypnotizer’s hand. Many persons are inclined to look askance at hypnotism as something shady, bordering on quackery and the occult. But the ability to induce trancelike conditions of the mind has been demonstrated beyond doubt. In skilled hands, the practice is not only useful but scientifically reputable. In this article a Professor of Psychology in Syracuse University tells— POPULAR SCIENCE MONTHLY 27 The Truth about Hypnotism OST of the superstitions of the past still survive in some degree. Especially is this true in the field of psychology, one of the youngest of the experimental sciences. The majority of people probably believe in telepathy or “mind-reading,” and yet this belief is lacking in experimental proof. Spiritism, the belief in the pos- sibility of communication with spirits of the dead, is also lacking in scientific verification. Hypnotism, though often associated in the popular mind with telepathy, spirit- ism, and occultism in general, is a differ- ent matter entirely. It has been accepted by the scientific world for almost half a century as a natural process explainable in terms of ordinary psychology without any mystery or “hocus-pocus” inherent in it. The antecedents of scientific hypnotism are, to be sure, shrouded in superstition. Mesmerism, for example, never gained acceptance within the bounds of modern science because of its implication of “animal magnetism” by which the mesmerizer was supposed to accomplish his results. Mesmer, who mystified with the practice a century and a half ago, had orig- inally been a student of astrology, and he took over the astrological notion of the influence on human fate of mysterious planetary and stellar forces into his theory of the influence of certain persons over others. Though hypnotism involves By WESLEY R. WELLS nothing of “animal magnetism,’ telep- athy, domination of weak wills by strong wills, or supernormal influences of any sort, the hypnotic phenomena them- selves are sometimes so ‘extraordinary that persons witnessing them for the first time often find it hard to believe what they see. Surprising conditions and proc- esses may be induced in normal people. The bodily movements of the hypnotized subject may be controlled, arms or legs may be paralyzed, and the whole body rendered cataleptic. Other possible effects are illusions and hallucinations, blindness, deafness, complete anesthesia, loss of memory (amnesia), and increased mem- ory (hypermnesia) for long past events. Two years ago I had an interesting illustration of the use of hypnosis in re- covering memory for forgotten childhood experiences. A young man reported to me that he recently had learned that his supposed parents were only foster parents, his own father and mother having died when he was a small child. He wished to have hypnosis used to aid him in recalling his own parents. Under hypnosis he re- called that, after his father’s death, his mother was forced by poverty to move to a slum section of the city. His foster parents had concealed this from him, but later admitted the truth of it. He even remembered under hypnosis the funeral of his mother, which occurred when he was two and one half years old. TILL other possibilities are alterations of personality and artificial, tempo- rary cases of double personality, each personality being unaware of the other. In addition, so-called posthypnotic sug- gestions may be carried out. These con- sist of commands given during the hyp- notic state to be carried out afterwards, sometimes weeks or months later. They are typically carried out without any memory by the subject of the original command in the hypnotic state. The sug- gestions may be in the nature of actions to be performed, of hallucinations to be experienced, or of anesthesia, of loss of memory, and, in fact, prac- tically any of the phenomena capable of being produced in the — ability to hypnotize demands no unusual powers,” says Professor Wells. “Nearly anyone who has watched the process can get some results in hypnotizing others. There is no justification, however, for the use of hypnotism for entertain- ment. Unskilled amateurs might do all sorts of injury to their subjects.” hypnotic state itself. The subject may be made to go into the hyp- notic state at a later time imme- diately upon the presentation of some agreed-upon signal, such as the clapping of the hands or the flashing of a light. Or the subject can be rendered unsusceptible to hypnosis in the future. Within limits, there may be

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! : 5 ! ‘ 1 . One of Professor Wells’ students perform- ing automatic writing with his arm in a sling to facilitate movements. The writing at the right was done by a healthy foot- ball player without being aware that his hand was moving. It is part of a descrip- tion of a forgotten childhood incident. produced changes of physiological proc- esses not subject to ordinary voluntary control, such as alterations in the pulse rate, variation of the body temperature, changes in some of the glandular secre- tions, alterations of the functioning of the digestive system, and perhaps the production of tissue changes similar to blisters without the application of heat. This last group of processes, though re- perted by some of the workers in the 1880’s and 1890’s, and though verified to some extent in recent experimental work, is still open to some question among sci- entific investigators. N THAT connection, hypnosis has a very practical use, however, in showing the reality of so-called functional illnesses involving severe pain. When a person suffers, for example, from a persistent headache for which medical diagnosis reveals no organic basis and which does not yield to ordinary medical treatment, and when the physician finally labels the headache a hysterical symptom, friends sometimes think that the headache is “imaginary,” and that the person is not really ill. The truth is that the headache in such a case is just as real and painful as if it were caused by a brain tumor. A surprising illustration occurred several years ago when I attempted a repetition of the so-called blister experiment. A newspaper item had reported the case of a woman who had encountered a rattlesnake, who thought she had been bitten, and who soon began to suffer pain with marked swelling in one ankle, even though the snake had not actually struck her. Question arose as to the possibility of this, and one of my students proposed that an experiment be tried, of a somewhat analogous nature. I put the student into the hypnotic state, laid a half-dollar on one forearm, said it was a hot iron (the subject writhed with pain), said the iron was getting a little cooler so that he could endure it (the writhing subsided), and said his Professor Wells at his desk at Syracuse University, con- versing with a student in psychology department. POPULAR SCIENCE MONTHLY that the heat would remain constant for twenty-four hours, during which time a swelling of the arm and a tissue change resembling a blister would appear. The subject was aroused from hypnosis and instructed to keep notes on results, and to report to me if at any. time the pain became too great to bear. Unintentionally I had over- looked one point, which was this: If a hot iron at constant heat were actually applied to one’s arm, the pain would not remain constant, but would increase. I had said that the heat would remain constant. It did so (in the sub- ject’s experience), and the pain increased. Results are indicated by quotations of parts of the notes which the subject kept. The experiment had started at two o’clock. At 2:26 o’clock he wrote: “In bed with pain. Pain severe. Hot. Writhing. Consciousness almost blank. Can do nothing but try to relieve pain. Hot, sizzling. Cannot bear touching.” At 2:40 o’clock he wrote: “Am crying with pain. Can write no more.” The subject then sent for me. When I arrived, I found him almost in a state of collapse. I immediately terminated the experiment, of course. I did not produce any tissue changes resembling a blister, but I did produce a very convincing demonstration of the reality of experi- enced pain without ordinary organic basis. Should not this teach us patience and sympathy with those suffering from hysterical disorders? Such persons are Marcu, 1939 really ill; they really suffer; and they neeq the appropriate kind of treatment. Various methods are employed to pro. duce hypnosis. Simply talking to the subject is the most important. One psy. chologist recently had recorded on a pho. nograph record (to be distributed only to psychologists and to physicians) 4 series of sentences spoken in a monoto. nousand commanding tone to bring about the hypnotic condition in those who hear the record. NOTHER method is that of fixed gaz. ing, of having the subject look fixedly at asmall object such asa pencil held either in his own hand or in the hypnotizer’s hand. Sometimes the verbal method js supplemented by so-called “‘passes;” that is, strokings of the face, arms, or body. Such manipulations are intended to bring about a relaxed and perhaps drowsy state, such as one may experience when in the barber’s chair enjoying the manipulations of the barber. Relaxation and concentration of the attention aid in the success of the work. The continuous and monotonous repetition of simple words and acts is one of the principal factors in the technique. If the common form of sleeping hypnosis is being pro- duced, there is simply the added feature of talk about drowsiness and sleep. No special apparatus is needed. The teach- er’s classroom attitude toward his class or the physician’s manner of talking to his patients may be used to advantage by the hypnotizer. HE technique of hypnotizing really is so simple that many persons at first cannot understand why it should bring about such startling changes in the subject. The common type of sleeping hypnosis is induced by a method some- what similar to that used by a mother in soothing her child to sleep by telling a bedtime story. Then, after the hypnotic condition is induced, it has similarities to a state of sleep. The ordinary sleeper is usually immobile. His dreams consist largely of illusions and _ hallucinations. He may dream of long-forgotten events, and he may completely forget his dreams upon awakening. Sometimes he may walk and talk in his sleep. In hypnosis such conditions, and others, are produced artifically —made to order. Another type in which sleep is not involved is so-called wak- ing hypnosis. This may be com- pared with states of absent- mindedness in everyday life in which unusual acts are some- times performed, with states of concentrated attention in every- day life such that sounds are not heard and pain is not felt, or with lapses of memory when even the names of best friends are forgotten. In waking hyp- nosis such conditions are brought about by the words and acts of the hypnotizer. Who can be hypnotized? Perhaps all people except young children, the feeble- minded, and the mentally (Continued on page 161) MaRCH The ne ing mec pedesta are tc New 350 of Canac news Stock found Wh of sto marke of last four I financ cribec ly to repor old 1 print, 285 c ute; will b many new on 0 stalle next | be sf new speed partl: tion over ticke teen impu on th ate brain

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Marcu, 1930 POPULAR SCIENCE MONTHLY NEW IDEAS AND INVENTIONS On this and succeeding pages are presented the latest achievements of inventors, including important devices and _ processes, together with useful methods for making and doing the old things in a better way The new stock ticker. The print- ing mechanism is exposed on the pedestal with the roll of tape. HE stock ticker is to tick no more. New high speed machines that whir instead are to be installed in brokers’ offices in New York, Chicago, San Francisco, and 350 other cities in the United States and Canada. They will record by telegraph news of transactions on the New York Stock Exchange, replacing old machines found too slow for modern trading. When more than sixteen million shares of stock changed hands in the New York market on the famous “Black Tuesday” of last October, the old-style tickers were four hours late. Many financial experts as- cribed that panic part- ly to the inadequate reporting service. The old machines could print, on the average, 285 characters a min- ute; the new tickers will be able to print as many as 500. As soon as_ 10,000 new tickers now on order are all in- stalled, probably by next October, they will be speeded up to the new pace. The high speed has been achieved partly by simplifica- tion of the code sent over the wire to the ticker. Formerly seven- teen separate electrical impulses were required, on the average, to actu- ate the mechanical brain inside the ticker The great control board which feeds high speed ticker signals to offices in the downtown section of New York. The “distributor’’ at right passes code signals to cylinder-shaped re- lays, one for each city, to be flashed over a nation-wide wire network. Where the ticker news comes from—an interior view of the main transmitting office next door to the New York Stock Exchange. and make it print a letter or a figure. Now the number is reduced to eight. These code impulses operate a mecha- nism much like the combination lock on a safe. One by one, they set “tumblers,” or metal stops. At the final impulse an electric motor spins a printing wheel, carrying letters and figures. The “com- bination” stops the wheel when the proper letter or figure is in position, and a hammer springs up and prints the char- Speeding Up the Stock Ticker acter on a tape. Through a second improvement, the “‘com- bination” is reset for a second letter even while the first one is being printed. An electric motor within the ticker drives it from local power. The old models worked by clock- work, wound by electricity and requiring an extra wire from the transmitting station. To keep pace with the high speed of the tickers, an acceler- ated stock reporting system will be used. In the central office _two operators working side by side, instead of one, will receive quotations from the floor of the stock exchange. They will type the quotations on special type- writers that perforate tapes running past them. An almost human machine known as a “tape transmitter” translates the perforations of the two tapes into the new code impulses. The machine has six pins or “fingers” that poke through the perforations and make electric contacts. From there the impulses go to a “dis- tributor,” through which they are passed on to the relays, one for each city, that flash the news out over a nation-wide network. Formerly human operators re- layed quotations at such “‘repeater”’ points, but now machines will take their places. Radio-Sound Fog Signal GHORNS will not only give warning, but will tell afog bound captain just how far he is from shore, if anew radioand sound wave device now being tested at Cum- brae Lighthouse, near Glasgow, Scotland, comes into general use. At the instant the foghorn blows at the lighthouse, an auto- matic radio transmitter begins vocally to count off ‘‘one,’’ ‘‘two,’’ “three,”’ and so on, at intervals of five sec- onds, the time required for sound to carry one mile. The speed of the radio waves is so great Ae ” ny ‘ amore OPP NE TTL ER UF LIN OS Serer ee Se eS ee ee ee ere C4822 ot the ite ho vx a

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30 that time required for them to reach the ship can be disregarded. Hence if the man on the bridge of the ship, with a radio receiver on one ear and the other ear open to catch the foghorn, hears the horn at the same time as the word “two,” that means the ship is two miles from shore. The word “three” would signify three miles, and so on. Fog Piercing Lamps for Railway Signals NUSUALLY powerful electric signal lamps that flash their colored beams for miles and are visible through fog and bad weather by day or night are being employed to supplement the familiar semaphore signals along the main lines and in the yards of American railways. The penetrating red and green lights are said to reduce the chance of a locomotive engineer mistaking or running past a signal. The photograph above shows one of the signals installed near the ground in the yards of the Terminal Railroad in St. Louis, Mo. Steam and Diesel Engines Drive Speedy Warship VEN more of a surprise to the engi- neering world than the “pocket battleship ” Ersatz Preussen which created a sensation last year is the Leipzig, a new water dragon of the German fleet capable of holding a speed of thirty-two knots or thirty-six miles an hour. The Leipzig is a 6,000-tonner of the cruiser type, powered with both oil and turbine engines able to work independently, and will have the capacity for a cruising range of 11,000 to 12,000 miles at a speed of eighteen knots. With both engines working to- gether at full power she will be able to maintain the tremendous speed of thirty- two knots for a longer period than any naval vessel afloat. She is said to be the first vessel to em- ploy both steam and Diesel engines for propulsion. Her hull is provided with large bulges, intended primarily as an antitorpedo device, but capable of use for the emergency storage of vast amounts of oil for fuel. POPULAR SCIENCE MONTHLY New Safety Glass Resists Fire and Bullets “W7ETAL,” a new safety glass said to be proof against fire, splintering, or discoloring has been patented by an English firm and subjected to rigorous laboratory tests. When service revolver bullets were fired at the glass at distances of ten and twenty-five yards, it is report- ed, the glass was pulverized to a depth of only one thirty-second of an inch. More severe tests ensued. A powerful mercury vapor lamp was played upon the glass over a twenty-four-hour period and no discoloration resulted, a decided con- trast to ordinary glass, which will be dis- colored even by the sun’s rays in tem- perate zones. Resembling ordinary glass in appear- ance, xetal can be made in any shape or size and in any thickness, from that of the best lens-making glass to the bullet- proof variety. Slot Machine Deals Out Water, Soap, and Towel URNING on its own water supply, and handing out a wax paper packet of powdered soap and a towel, a new “automat,” recently displayed at an ex- hibition of automatic machines in Berlin, Germany, furnishes all the materials necessary for a thorough wash. All the customer need do to obtain service is place two ten-pfennig coins, the equiv- alent of approximately five cents in American money, in a slot and pull a - handle. The machine will do the rest. Rare Metal in Quantity ITHIUM, a metal so light that it easily floats on water, is now to be avail- able in tons instead of pounds, as here- tofore. Through a new quantity pro- duction method developed by Dr. H. M. Partridge, New York University chemist, it will cost at wholesale rates only $15 a pound. Hitherto chemical laboratories have sold it at $240 a pound. Lithium is the world’s lightest metal. It weighs only one fifteenth as much as Marcu, 1939 : iron, and half as much as water. Silvery in color, softer than lead, and easily aj- loyed with other metals, it blackens and burns spontaneously when exposed to the air. Samples of the pure metal are kept under oil to keep them from decomposing, One of its important uses is to impart sweet tones to great metal bells. It is also used in aviation to purify helium or balloon gas by absorbing impurities. Its spongelike action increases the lifting power of helium about fifteen percent. New uses are likely to follow the pro- duction of the metal in quantity, accord- ing to Dr. Partridge. Sun Baths on the Train | egos cars are the latest things to be equipped with windows of “health glass’”’ which transmit the bene- ficial ultra-violet rays of the sun. Travel- ers to the south of England, bound for Cornwall and neighboring sunny winter resorts, now have available a special ex- press service equipped with the “sun bath” cars. Thus passengers are assured of the full solar benefits of their vacation from the moment it begins. Combination Stepladder Will Rest on Stairs ESIGNED for a wide variety of uses about the house and yard, a new combination ladder invented in California can be made to serve as a short, straight ladder, an extension ladder, a stepladder, or one that can be adjusted to rest on the steps of a stairway. The new accessory is built like an ex- tension ladder, in two parts. The parts may be separated, then set together at an angle to form a stepladder, with rungs (or steps if preferred) on both sides. A special locking device fits about the top and keeps the entire structure rigid. If the ladder is to be used on a stairway, the relative height of the two parts has merely to be accommodated to the inequalities of the stairs, and the locking device holds it firmly in that position. The new combination ladder set up on the front steps. A locking dev.ce holds it securely. Marcu, | Car While the being intr manufactu extreme ir above. F engine an trunklike chassis, be omy in po’ of unspru: New Accelerat in one pe control sk the pedal pressure ' closes a c magnetics circle) wt that appl. ates on t

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ery ‘0- rr SS @ el MARCH, 1930 POPULAR SCIENCE MONTHLY Car before the Motor While the new front-wheel-drive car is being introduced in America, a British manufacturer has gone to the opposite extreme in the unusual model pictured above. Retaining the rear drive, its engine and radiator are placed in a trunklike compartment back of the chassis, between the rear wheels. Econ- omy in power transmission and lessening of unsprung weight are said to result. New Electric Auto Brake Accelerator and foot brake are combined in one pedal in the new electric brake control shown below. Toe pressure on the pedal works the accelerator; heel pressure works the brake. The latter closes a circuit and actuates an electro- magnetically driven solenoid (in the circle) which, in turn, moves the cams that apply the brake. The device oper- ates on the usual six-volt car battery. In the Classroom Students in the American Hospital studying an eye operation projected on the screen from the operating room. The view of the patient is greatly enlarged by the means of lenses. 31 Surgery in the Movies— The motion picture camera and screen are playing an increasingly important part in the training of medical students. In the clinic of the University of Berlin, Germany, has been installed the special movie camera pictured above. Focused on the operating table, it makes a film record of every step in the surgeon’s work. Later the film is thrown on a screen in a classroom, so that students may study the technique of the opera- tion and make notes. Another method to the same purpose is described below. 4. —and by Magic Lantern Instead of the movies, the elaborate ap- paratus shown at the left is used in the American Hospital in Paris, France, to reproduce scenes of an operation for students. Suspended above the oper- ating table, it works on much the same principle as the familiar magic lantern which projects photographs or post cards on the screen. By a system of mirrors and lenses, it transfers the scene instantaneously to a screen in an ad- joining room, where the students are assembled. They also hear the voice of the surgeon describing the operation. Sones deen aaiehdsdeh ae - ee) Se PURIST i y if E ' ‘i 4

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32 High-Speed Photographs Make Whirring Wings Stand Still “ ARRESTED motion” photographs at extremely high speeds may open a new world for nature study in the future. A bee’s wings, it has been computed, beat at a rate between 2,000 and 3,000 times a second. But Joseph A. Speed, A.R.P.S., of London, has caught a bee in motion with a shutter so quick that not only were the wings shown stationary in the resulting photo, but even minute details and markings of the wings were revealed. Other achievements of his new flashlight camera include catching a swallow in flight and snapping a stoat or ermine on its leap to a limb, the photo showing the ani- mal’s feet entirely free of any part of the limb. In order to get these pictures the shutter of the camera clicked within one five-thousandth of a second. The marvel of the camera mechanism lies in its ability to time the flash exactly with the shutter. The photcs were first publicly shown at the recent seventy-fourth annual International Exhibition of the Royal Photographic Society in London. Welded Steel Floors for Higher Skyscrapers N THEIR efforts to design higher sky- scrapers architects are limited by an enormous dead load of flooring. To lessen this unnecessary burden on the building’s supporting structure, a new type of floor panel construction has been invented by steel engineers. This revolutionary floor- ing, demonstrated recently before the American Institute of Steel Construction, is designed to act as a solid steel girder embracing the whole girth of a building, preventing tortional quirks and reducing the danger of high wind or earthquake action. So much lighter is the new floor- ing than the old, that for a seventy-five- story building it is calculated to save 2,000,000 pounds of dead load on the foundations for each column. This, it is said, would permit an increase of twenty- five percent in the height of the building. Thus may the dreams of 100-story build- ings, become a reality. The new so-called “battledeck” floor- ing consists of plates “stitched” by a new automatic arc welding machine comprising a self-propelled vehicle carry- ng a wire feeding device, a reel of welding wire, and arc welding apparatus. Dustless Garage Cleaning HEN garage floors become covered with dust and spotted with oil, a sprinkling of sawdust or sand saturated with kerosene assists in the cleaning. It prevents clouds of dust from rising during the sweeping and the kerosene removes most of the small oil spots. POPULAR SCIENCE MONTHLY This rapid motion photo caught an ermine in the act of leaping to a limb. Notice that not one of the an- imal’s feet is touch- ing the tree branch. Knockdown Desk and Seat for the Schoolroom LIGHT combination desk and seat, which can be adjusted to suit any child from four to ten years of age, has been devised by a California inventor, who claims that the equipment weighs at least ten pounds less than the present standard school desk, is just as service- able, and costs half as much. The top of the desk consists of a shal- low box of thin wood, made with a black- board on the outside of the lid for small children and with plain top for larger pupils. At the upper end of this lid rises A small schoolboy copies a drawing on the blackboard lid of the new knockdown desk. A remarkable flash- light photograph of a swallow in flight, made pcssible by the fast camera shutter. The wings appear stationary. Marcu, 1936 a holder for drawings or other material the child may have to copy. Inside the box are spaces for paper and writing utensils. The box itself may be closed with a catch and carried as a school box, to and from home, if desired. Seat, legs, and standard to hold the desk consist of five flat pieces. Mortises and tenons bind the whole to- gether solidly so that it may be moved as easily as a standard desk. Tunnel Lined with Wood ELLOW pine lumber has entered the field of tunnel engineering with the building of the new water conduit from the River Rouge to the Ford Motor Com- pany Plant in Detroit, Mich. From the bottom of a seventy-foot shaft twenty hydraulic jacks are driving an enormous steel shield horizontally through the earth to make a circular tunnel nineteen feet in diameter. As the tunnel grows behind the path of the advancing shield, it is lined with long yellow pine boards, held in position by the pressure of the earth. Eighty thousand feet of board are so installed daily. Heretofore the material ordinarily used for such tunnel lining has been cast iron. The chief advantage of the new tunnel material is its economy. Chemicals to Remove Snow HE problem of snow removal in large cities may be solved by chemistry after this year. Chemical methods of breaking up snow and ice along the gut- ters have been tried out this winter, par- ticularly in the Boroughs of Manhattan and Brooklyn in New York City. In the latter borough, following a recent storm, four ice-caked streets were sprinkled with pellets of calcium chloride, the melting effect of which was said to be noticeable within a few hours. The manu- facturers of the chemical claim that the pellets will drain snowdrifts down the sewers. Passen Domin Nova § tion p choked dust ci tangul: ered w: attache of the below constrt easily |

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her > to ices sils. sed the the om m- the ity US the ws Marcu, 1930 Dust Catcher Passengers on crack trains of the Dominion Atlantic Railway in Nova Scotia can sit on observa- tion platforms without being choked by swirling dust. A new dust catcher consists of a rec- tangular frame of iron pipe cov- ered with a screen of canvas and attached horizontally to the end of the observation car a foot below the floor level. Of light construction, it can be detached easily and quickly for cleaning. A **Step-Over’’ Trolley POPULAR SCIENCE MONTHLY 33 An All-Purpose Saw By changing blades, this new adjustable saw can be used to cut stone, iron, steel, or fiber, as well as wood. It also will cut at any desired angle, or make circular grooves. The circular blade is attached to an arm which moves on ball bearings. Submarine Rescue Tube Sixty-five feet undersea, the crew of the Italian submarine S-17, in recent tests near Spezia, Italy, entered a newly in- vented safety tube and shot to the surface in six minutes. At sixteen feet depth, others of the crew escaped wearing only bathing suits. The tube leads to an escape reservoir on the submarine, where water is held back by air pressure. At left: Donning diving suits for escape from the submarine. Below: The members of the submarine’s crew reaching the surface. t 7 { ; iti > | it 5 ft : | | H he Moving metal “‘fingers’’ that suspend the load Self-Sharpening Razor All the shaver need do to keep a keen edge on this novel razor, the he from this new cableway trolley are said to lift a inventor claims, is to shake it once in a while; for it combines in one unit a blade, a hone, and a strop. five-ton load over crosswise cable supports, thus The shaking is said to move the blade edge over a sharpening surface to which a special chemical solving satisfactorily an “impossible’’ problem. abrasive has been applied. These views show the new safety razor and its self-sharpening mechanism.

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SE Fe SE Sa Oe ES! PaO Te ew ene MI ry ue PAG egemerue Se east ant — es —— es 34 New Grade Crossing Signal Light O REDUCE the increasing number of fatalities from automobile-train col- lisions, the German government recently introduced special railway signal lights for automobile drivers at grade crossings. White and red are the colors used, corresponding to the green and red lights ordinarily used for railroad signals. When the track is clear, a con- tinuously-blinking white light in- forms the motorist that he may cross, giving a positive assurance of safety. An approaching train makes an electric contact that changes the light to a red flash signaling “danger.”’ Concentrated by a screen, the light is plainly vis- ible by day and night. Steam Heated Gardens Ug ae nagge see dy steam heating plants may be the next item on the list of agricultural implements. Heat- ing the soil has been found by an Eng- lish chemist, Dr. W. F. Bewley, Director of the Experimental and Research Sta- tion at Cheshunt, to destroy pests and diseases and to increase soil fertility. The method involves heating the soil for about half an hour at the temperature of boiling water. Heavy soils require more heating than light, sandy soils. Disease-producing bacteria and fungi are said to be destroyed without killing the beneficial soil bacteria. The heat also breaks down complex chemicals into simpler ones useful for the soil bacteria. Heating must be thorough, says Dr. Bewley, and is best carried out by run- ning a current of steam through the soil. Baking is all right but dangerous, as over- baking leaves the soil dry and ruins it. Advocates Flying Clinics for Frayed Nerves ** AIR CLINICS” for nervous and run- down patients are suggested by C.L. Julliot, French lawyer. With the re- ported approval of the medical faculties of France, he proposes airplane rides as a tonic for the nerves. Every hospital might maintain an airplane or two for the use of its patients. Physiologists have long known that brief visits to the tops of habitable moun- tains cause changes in the human body, particularly in the blood. However, there is little quantitative data as to the proper “dosage” of high-altitude expo- sure, or the exact effects it produces upon human beings. Aside from high peaks, there are only a few places in the United States where such tests could be made. The United States Bureau of Standards at Washing- ton, D. C., has an “altitude chamber” in which it now tests the effect of high alti- tude upon motors. Another place where upper-level effects could be duplicated is the remarkable globe-shaped hospital at Cleveland, O., where diabetic patients now can live in an atmosphere of more than normal pressure. Here powerful vacuum pumps could as easily maintain a The crossing signal at night. Its brilliant white light changes to red when a train approaches. POPULAR SCIENCE MONTHLY pressure below that of the atmosphere. When the exact effect of such treat- ment upon the human body is known, ‘‘flying clinics” may provide this tonic of the upper air and add the zest and thrill of aviation. Not only airplanes, but dirigibles of large passenger capacity might be fitted to fill any doctor’s pre- scription for “high living.” Found—Easy Way to Open a Cardboard Carton HANDY tool for slashing open a card- board or fiber carton with a straight line cut, so that the container may be used again, is the recent product of a New York City manufacturer. Simple and speedy in operation, it can be used to open either small packages in the home or large shipping boxes in stores and other business houses. The tool consists of a handle with spreading wings at one end, between which is inserted a blade, not unlike a razor blade, that is held secure by a spring. The wings of the handle are set at right angles to each other, so that they fit over the edge of the carton to be cut and guide the blade in a straight line. When a blade is to be inserted, one of the wing flaps is raised, revealing the spring. The blade is inserted beneath the spring, the flap is shut down and locked in place, and the tool is realy for work. Sliding the razor-bladed tool along the rim cuts off the lid without damaging the carton. A daytime view of the new warning signal installed at a grade crossing in Germany. It contains powerful Jamps and reflector. Marcu, 1939 a Baars Sree Ship-to-Shore Telephone Service Opened HE first “ship-to-shore” telephone service by radio was opened on a recent eastbound voyage of the steamship Leviathan. Seated at his desk in the offices of the American Telephone and Tele- graph Company on Broadway, New York City, Walter S. Gifford, President, took up the phone and asked for “the United States Liner Leviathan, somewhere at sea.”’ His voice was carried through a new transmitting station at Deal Beach, N. J., thence to a station at Forked River in the same state, and finally reached the radio- phone receiver of the great liner 200 miles out on the Atlantic. Other calls were put through from New York, Washington, D. C., Atlantic City, N. J., Indianapolis, Ind., and several other cities at the rate of seven dollars a minute. With good weather conditions it is claimed that the Leviathan should be able to establish phone contact with the shore at a range of 1,500 miles. Telephone officials say that the vessel will offer twenty-four-hour phone service whenever it is within range of American transmit- ting service. President Gifford predicts that eventually every ship on the seas will be linked by radio to the shore and thence by wire to any telephone. Speedway Atop a Railroad BOVE the twenty-six-mile stretch of the Grand Trunk Railway running from Detroit to Pontiac, Mich., a four- way automobile toll road mounted on steel pillars will be built. This is said to be the first instance in which the air rights of a railway have been used for automobile traffic speedway purposes in the United States. The speedway will en- able the motorist to cover the twenty-six- mile distance easily in thirty minutes. It will pass over all intersecting streets and railroads, will be encumbered by no traffic lights, and will be zoned. Traffic will enter and leave by way of ramps built at important intersections. The first step in the construction of the roadway will be the electrification of the railway under- neath at a cost of $100,000,000. Mar The just ates whic awa} the il moti The inge! intal a yor of o; clute can plac ih Res« life-] Albe avia airp is pi plac of t hea bow the is si tral

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NPB EE 4 ant Sh vette: ib aS sabe 1e€ none na ship fices “ele- Tork took ited : at new the dio- iles New ity, ther ute. t is ible lore one ffer ver nit- icts eas ore Marcu, 1930 POPULAR SCIENCE MONTHLY 35 Vacuum Gear Shift The touch of a finger tip on a lever just below the steering wheel oper- ates a new auto gear-shifting device which works by vacuum and does away with the usual shift lever. It is the invention of J. H. Newmark, auto- motive engineer of New York City. The vacuum required for operatioa is ingeniously supplied from the motor intake manifold. In the photo above a young woman demonstrates its ease of operation in conjunction with the clutch. The mechanism, it is said, can be installed in almost any car in place of the standard gear shift. Santos-Dumont Invents Life-Line Catapult Resembling a giant crossbow, a new life-line catapult has been devised by Alberto Santos-Dumont,the Brazilian aviation pioneer who made the first airplane flight in Europe in 1906. He is pictured below with his invention placed in firing position. The “‘string’”’ of the bow consists of two wooden arms which, when drawn back, bend heavy flexible bands that form the bow. The missile is a slug to which the life line is attached, and which is shot along a groove in the cen- tral shaft when the bow is sprung. Home Talkies Arrive An amateur talking motion picture outfit in combination with a radio receiver is the latest thing in home entertainment. Produced commer- 42 cially, the talkie apparatus com- prises a motion picture projector and phonograph. A 16-millimeter picture film is carefully synchronized in movement with the phonograph disk on which the voice is recorded, the timing being accomplished by an ingenious electrical hook-up. Rogue’s Gallery Photos Standardized More certain identification of criminals is the purpose of this new camera designed to standard- ize photographs by automatic control of lighting, exposure, and focus. Strong, diffused light assures clear pictures and avoids distortion of the face. The Car Makes Its Own Gas The idea of making a motor car manufacture its own gasoline is embodied in this apparatus devised by D. E. Fowler, of El Paso, Tex., (above) for the use of crude oil as motor fuel. It consists of a cylinder attached to the engine and acting as a portable still for producing gasoline by the “cracking’’ process. Another new crude oil device is shown on page 37 of this number.

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36 POPULAR SCIENCE MONTHLY Marcu, 1939 Shotgun “Camera poeta Check Sportsman’s Aim CAMERA attachment for a shotgun is the latest invention to enable a sportsman to test his aim as well as the accuracy of the weapon itself. At the touch of the trigger the gun fires a ‘camera-cartridge”’ as well as the usual charge of birdshot. The camera appara- tus, fitted to the stock and lying under the gun barrel, contains four small car- tridges each capable of taking a miniature photo about seven sixteenths of an inch in diameter. In the upper corner of the photo appears the arc of a circle, repre- senting the end of the barrel. The posi- tion of the target in relation to this cloudy arc indicates the probability of the shot charge reaching its mark. The illustration shows how shot and camera shutter are synchronized. A catch (D) connected by wire to the trigger of the gun releases the camera shutter (A) from a small notch (C) when the gun trigger is pulled. The shutter, operated by a rubber spring (B), exposes a sensitive plate (F) through a lens (Z). An ultra-rapid photographic plate must be used. To determine the accuracy of the aim by means of the final negative, an intri- cate calculation is needed, for when the exposure is made the shot charge still has thirty yards to travel, making a differ- ence of about one fifteenth of a second. And the position of the “killing circle” with respect to the bird can be figured out precisely only if the speed of flight of the bird is known. The photos, how- ever, are said to give a close enough estimate for practicable purposes. Cooling the Telephone a ” telephone receiver, designed to take the dis- comfort out of lengthy conversations in hot weather, has been invented by an English engineer. Made of special ma- terial, it is said to contain a new kind of freezing mixture which becomes per- ceptible only when the warmth of the ear is applied to the casing. Brush Holds Shaving Kit NOVEL convenience for the travel- ing man is a “knockdown” shaving brush with removable bristles and carry- ing shaving cream and powder within its handle. In the cap that screws over the butt of the handle fits a little round case containing powder and puff. Cream, in a tube within the handle, is released by pressing a button on the handle’s side. pan . *. me MANE ais. vin : The shaving brush kit with cap oe the handle removed, showing the powder case and puff. Shotgun with camera apparatus fitted to the stock under the barrel. = At the right: four of | oe the camera cartridges. At right: One of the camera cartridges, showing the mecha- nism which operates the shutter when the gun trigger is pulled. Enlargements of cartridge photographs. Left to right: Aim too much at the right; partridges in the “killing circle’’ New Electric Typewriter Prints Whole Phrases AN ELECTRIC typewriter designed to print words and phrases in addi- tion to single letters is the invention of Clyde C. Balston, of New York City, who claims it will write a business letter five to twenty-five times faster than the usual machine. It is designed especially for billing and office work. More than ninety percent of all the words required for business correspondence may be printed as words, the inventor claims.- Other words may be typed out in the usual manner on a standard keyboard with which the machine is equipped in addi- tion to its special keyboard. The new typewriter is reported to be practically noiseless in operation. To form the words, electrically-rotated bands of type are stopped by means of selectors controlled by the keys. Two keys are pressed down to form each word or phrase. One brings the selecting mechanism into play and the other stops the rotating bands of type at the right place to spell the word. Thus phrases such as “by return mail,” “My Dear Sir” and “Very Truly Yours” can be written, it is explained, with no more effort than is now required to type a word containing two letters. An Ingenious Lock Nut NUT that can’t be shaken loose, yet comes off easily with the turn of a wrench, has been invented by a French mathematician, H. L. Dardelet, and is now manufactured in this country. It is used with a special bolt. The harder one tries to twist it, the harder it grips. Yet press down ever so slightly, and it twirls off in a jiffy. The secret of the nut lies in the slight ; accurate aim—the bird in the “killing circle’; aim too much at the left. taper given the edges of the square-cut threads, and a corresponding slant of the bolt’s shank between its threads. The effect is that the nut spins loosely into its position. Then a couple of turns with a wrench actually force it onto a thicker part of the bolt; it is as if it had been rammed part way up a bolt too big for it, although not forcibly enough to damage the steel. It locks so firmly that no lock washers, cotter pins, or similar devices are necessary. However, a reverse turn with a wrench relieves the locking pres- sure and removes the nut readily whenever desired. Expedition Sets Sail in Vibrationless Yacht MOOTH sailing” is the motto of an expedition of scientific and business men which recently left the Tebo Yacht Basin in Brooklyn, N. Y., for the Gala- pagos Islands. The new vibrationless yacht, Olive K, owned by Charles F. Kettering, head of the General Motors Research Laboratory in Detroit, is the ship of adventure which the expedition- ists are trusting to keep them from sea- sickness and jiggling bunks. To eliminate vibration the two pro- pellers are synchronized, or timed to- gether. Alternating current generators are built into the flywheels of the two Diesel engines, with controls so arranged that they lock the engines electrically and make them run at exactly the same speed. To prevent pitching and rolling as far as possible, the ship is equipped with a gyro stabilizer. POPULAR SCIENCE MONTHLY will be glad to supply, whenever possible, the names and addresses of manufacturers of de- vices mentioned on these pages. Marc Figl Stre Instes est ty harm! smotk Thep above blaze

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30 a OO Es oe we er OR we we eT = — _ Marcu, 1930 POPULAR SCIENCE MONTHLY won | mee erst ea 2baae 4 > Beet er bist 0 ec 4G ad =~ © \Shabi : Ag aaad 3 . _-- fe as jx a tk eee ae) f a ee oe; Subway Moving Sidewalk Above is a working model of a new nonstop moving sidewalk system demonstrated by its inventor, Herman E. Taylor, traffic super- visor of Detroit street railways. It comprises two worm-driven belt conveyors, one carrying seats and moving at a constant speed of 20 to 25 miles an hour, the other starting at % mile an hour and accelerating to speed of the other in 9 seconds. Passengers would step from one to the other. The system would be underground. Fighting Fires with Streams of Powder Instead of water or liquid chemicals, Germany ’s new- est type of fire engine pumps through the hose lines a harmless carbonic acid powder which is said to smother flames without damage to fixtures and goods. The powder pumping machine is pictured in the oval above. At the right firemen are seen “‘powdering’”’ a blaze in an outdoor demonzstration of the method. An Eight-Ton Armful This motorized “lumber buggy”’ supersedes the horse-drawn two- wheel cart in Pacific Coast mills to speed the transportation of lumber about the mill yards or to shipping docks. Straddling a pile of lumber, it lifts it bodily at the touch of a lever and carries it away at a speed of 15 miles an hour. The load pictured above contains 5,600 feet of lumber. 37 Fuel Oil Carburetor Joseph Graziano, New York shoemaker, has devised a car- buretor which, he claims, per- mits use of fuel oil instead of gasoline in motor cars. It includes special spraying and heating chambers for vapor- izing the heavy oil. Photo- graph shows the inventor and his son installing the device. Featherweight Office Furniture A:uminum is the latest material used for des‘:s, chairs, and other office equipment. This chair, weighing only six pounds, can be lifted with one finger. The new furniture is fireproof, in addition. «

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38 POPULAR SCIENCE MONTHLY Takes the “Kick” Out of Rifle or Shotgun NOVEL “compensator” for the reduction of recoil peculiar to high powered rifles and shotguns has been introduced to sportsmen by a Connecticut manufacturer. It is claimed that it will reduce recoil fifty percent. Fitting on the front of the gun muzzle, it seems to get around the established physical law that action and reaction are equal, at least so far as the effect on the gun- ner’s shoulder is concerned. All that the latter should feel is a mild, gradual push—instead of a vigorous —., The secret of the shock absorption lies in what happens to the gases at the muzzle with the compensator attached. Gases issue from the muzzle of a military rifle at a pressure of about 5,000 pounds per square inch; from a shotgun at about three fourths of a ton to one ton per square inch. Within the body of the compensator the gases ex- pand, the bore of the compensator being larger than that of the arm, and the ex- pansion reduces the pressure. The re- markable high speed photos shown here illustrate how the gases escape sidewise through side cuts or ports of the com- pensator, instead of following in the direc- tion of the bullet or shot charge. The velocity of the gas is such that probably one half of it is carried forward and com- Household Ice Boxes May Go “Dry,” Too HE family ice man, vanishing before the spread of mechanical refrigera- tion, may come back—with a load of “dry ice’”’ on his shoulder. But his calls will be less frequent, ac- cording to Walter S. Johnson, one of the pioneers in developing the new refriger- ant, who made the prophecy before the American Society of Refrigerating Engi- neers recently. A sixty-pound cake of the new substance, costing about seventy-five cents, will keep a household ice box at thirty to forty degrees Fahrenheit for a week, he declared. This product, snowlike in appearance, is much colder than ice—about a hundred degrees below zero. Recently it has been used extensively for shipping ice cream and frozen fish and meat products, and, because of its compactness, it is preferred for the ice boxes of passenger airplanes that serve meals in the air. Burnt Toast Packed with Invisible Diamonds? HE possibility of making diamonds from burnt toast is suggested by Dr. S. Paramasivan, a brilliant physicist of Calcutta, India. Diamonds are carbon atoms packed extremely tight. The only difference between diamond carbon and lead pencil carbon is that the atoms in the latter are packed very loosely, like the crumbs of a sponge cake. Various kinds of carbon have different magnetic prop- erties. Dr. Paramasivan is an expert on these properties. To his surprise he finds Two of the new recoil suppressors, the large one at the left for shotguns and the smaller one for rifles. pressed by the slope of the forward end of the torpedo-shaped compensator. The re- sulting compression is accompanied by a forward reaction of the compensator body. This forward motion, or pull, tugging against the urge of the gun to kick the man’s shoulder, reduces the recoil. ee A shot charge, leaving the barrel of a shotgun without compensator, is pancaked by pressure. + : ; 7 ould P “ “ 4 : #y Riper Ss Bee OS vn —s A shot charge passing through the compensator tube. Notice the gases escaping through ports, Here the charge is leaving the tube, and gas escape is at maximum, counteracting the recoil. SPQ we Clear of the muzzle. The shots in the charge are perfectly bunched, without signs of scattering. a ; s ee eer i : The shot charge in flight forms a uniform, com- pact pattern. The powder wads are left behind. that many kinds of carbon, such as that of burnt sugar or a smoky flame, act magnetically like that of diamond carbon instead of like that of the graphite carbon of lead pencils. Apparently the carbon of burnt toast is made up of myriad tiny diamonds too small to be seen by a microscope, and might be turned into gems if someone were clever enough to put them together in the right way. But try and do it! Automatic Device Records Rhythm of Heart bbe hack work of laboratory workers in biology and physiology may be con- siderably lightened by the use of a time- saving invention recenfly perfected by a banker-scientist of Tuxedo Park, N. Y., A. L. Loomis, and described at a meeting of the National Academy of Sciences. It is a mechanism to record automatically natural rhythms of any kind, such as the heartbeat, the nerve impulse, or the flash- ing of a lamp. The living body is a network of such rhythms. Prof. E. N. Harvey, of Prince- ton University, made extensive studies of these rhythms with the aid of the new de- vice by isolating a turtle’s heart in a special liquid medium and recording the variations in its beat over a period of many hours. (A turtle’s heart will beat indefinitely after removal from the body, sometimes as long as thirty-six hours.) But here is the point of the invention. Formerly, if Professor Harvey had wished to make observations on the hear. action he would have had to stay in the labora- tory and take all the notes himself. Now the Loomis apparatus can take all the notes for him. It is geared in such a way that ten successive beats are recorded by a pen-drawn line indicating the time of the action. At the finish of ten beats the pen goes back to the zero line and s* urts recording again. The instrument cazx pro- long this process for any length of time, while the laboratory worker may adjourn to lunch, a game of tennis, or anything else that pleases him. Studying the fluctuations of bodily rhythms gives valuable data to physiol- ogists. The effects of drugs on the heart action is an instance of the problems that may yield their answers by such methods as Loomis’ mechanism makes possible. Alcohol from Watermelons N THE banks of the Volga River by the town of Stalingrad, Russia, a new factory has been established for the manufacture of syrup from the pink pulp of watermelons. This new product, known as ““Nardek,” will have its uses split in half; the better grades of the syrup will be used in cooking or confectionery, and the poorer grades utilized in the manufacture of alcohol. Looks as though “vodka,” the Rus- sian whisky, would be made from water- melons instead of from corn after this. Mar

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y- rt at ds ‘REELED INTO SKEINS (4) o ‘ Marcu, 1930 POPULAR SCIENCE MONTHLY From Wood Pulp to Rayon Silk %)) AFTER MERCERIZING, MATS ARE PUT INTO ~) A PRESS WHICH - OUT ALL POWERFUL GRINDERS IN SHREDDER CONVERT MATS INTO, CELLULOSE CRUMBS ‘OF; CELLULOSE IN THE er |AND VACUUM -TREATED TO REMOVE Al IN THE SPINNING MACHINE, A SYSTEM OF SPINNERETS AND BOBBINS, VISCOSE BECOMES @) VISCOSE SOLIDIFIES IN AN ACID BATH AND IS THREADED BY THE SPINNERET INTO RAYON FILAMENTS WHICH WIND ON THE BOBBIN SECONDARY SPINNING MACHINE WHERE TWIST IS PUTIN THREAD = (jz) THE CAKES ARE 53 i ARE ss WASHING, SODIUM Acio. 1D. ANOTHER ¥ FINISHING \y ROM wood pulp to artificial silk—a pictorial story of pro- gressive steps in the so-called viscose process of manufactur- ing rayon. Eighty-five percent of the world’s rayon now is made by this method, which was perfected in 1900 by two British chemists. The raw material from which are spun the fine silky threads is cellulose extracted either from the pulp THE CRUMBS ARE MIXED THE FINE WHITE ARE PACKED IN CANS AND AGED FOR THREE DAYS — MAKING ¢ THREAD BY THIS PUTS THE NECESSARY TWIST IN THE THREAD AND ELIMINATES | ON 3 BE NO.13 BUT IT agra ey SPECIAL . AKES, DRIED IN C i a HOT-AIR UNDERGO THOROUGH WASHING : + © : Drawn especially for Popctuar Science Monracy by B. G. Seielstad of spruce wood or from cotton linters—the coarse, left-over cotton fibers formerly discarded as waste. Ground into crumbs and treated first with carbon bisulphide and then with caustic soda, the cellulose is converted into a viscous or sticky solution which, when it solidifies, can be drawn into slender filaments by a spinneret. The filaments then are spun into thread.

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POPULAR SCIENCE MONTHLY Marcu, 1930 Flying with an Airship Captain The Veteran Commander of Navy Dirigibles Tells of His Experiences in Piloting the Los Angeles E WERE just back from Panama, one March night, and the Los Angeles was being hauled down to the ground in its second landing attempt. The men on the ropes and those holding the handrails on the outside of the cabins were walking the ship across the field to the hangar. Down the field a cloud of snow arose—a squall was approaching. It hit. The great ship swayed in the gust. Dragging the ground crew with her, she was swept toward the trees that border the field. “Let go all lines!” Overboard went water ballast. The ship leaped into the air. Five or six of the ground crew had not been quick enough to let go. Then they were afraid to jump. They were carried up, clinging like flies to the out- side of the cabin, their legs dangling in mid-air. Five hundred feet from the earth, they were pulled in through the cabin windows. Cruising about until the squall had passed, perhaps an hour later, the ship Control room equipment of the Los Angeles. C—magnetic compass; D—chart desk; E—elevator wheel; G—gas thermometer; H—helium gas release toggles and master valve wheel; I—inclinometer:, aneroid barometer, and stop watch; M—mooring force indicator; R—rudder wheel; S—searchlight; T—engine room telegraphs, telephone; V—height change indicator; W—water ballast chart and release. A—air speed indicator; B—barograph; experience. Once the Los Angeles narrowly avoided collision with an airplane at night. Another time she was shot at, in the air, by an over-enthusiastic New Jersey duck hunter. Torn fins have been patched high in the air, and our ships have flown through lightning storms. The high spots of a flight for an airship captain are its start and its finish. Launching an airship requires extreme care. The crew—say eight officers and thirty enlisted men—are at their stations in the ship, while the ground crew walks it out of the hangar. The captain walks out beside the mooring officer, who, from the ground, will direct the maneuver. The most critical part is getting the ship past the hangar door. At that moment a sideward gust on the huge bag might sweep it with thousands of pounds’ force out of the ground crew’s hands and QUADRON Commander of the B y Lieut. Commander CHARLES E. ROSENDAHL Chief Engineer’s assistant at his post at the engine telegraph control cf the Los Angeles. against the wall. The take-off is purpose- ly delayed until such danger is minimized, and when the ship is safely on the field the captain steps into the control cabin. A green flag, or at night a green lan- tern, in the hands of an orderly makes it easy to see where the mooring officer is. “Give us a weigh-off!”’ is called out to him. The buoyancy of the ship has al- ready been adjusted roughly in the han- gar, and this is the final weighing before we ascend. “Stand by to weigh off!’? commands the mooring officer. The order passes from mouth to mouth down the length of the 656-foot ship. The ground crew sets the control car and the after gondola down on the ground, holding them by the handrails along the sides. At a distance from the ship are the men on the handling at Lakehurst, N. J., Command lines. R dahlis A a Z ‘ * wal “Hands off!” They allow the ship to — page —s ee one Or rise to arm’s height, then at “Hold!” ity on dirigible navigation. Until May they bring it back, estimating the buoy- of last year he captained the Los An- ancy, if it tends to lift, by the weight of niin denial di the men required to hold it down. The ges, pegs Siege gga reports come in: “Four hundred pounds mand of the ill-fated Shenandoah. Here light, aft.” ‘Three hundred pounds light, he recalls some of his exciting experi- forward.” ences, and describes the interesting tech- nique of handling a 656-foot air liner. landed safely and was docked - in the hangar. United States Navy’s airship fleet That night provided the closest shaves the Los Angeles ever had. Only an hour or so before, in an attempt to tie to the mooring mast, rough winds had jerked the ship about so violently that a nine-sixteenth- inch mooring cable snapped just in time to save the frame- work of the ship from damage. Operating airships has pro- vided many an exciting That means that each end can lift that many pounds; in this case the total buoy- ancy of the ship is 700 pounds, a good MARCH, figure. too hea’ to rise fi aboard 1 forward now sat TA R¢ control cer pull the eng engines gong cl dolas. spin th stream elevato elevato to force as SOO! ground tugging the car literall; the air “Alle signal We're Alm averag the air ing wit hurst are ma recent at Cl stratec at tha peated time t bea rc Our ama ¢ each 1 sea, al on the toga. Nort signs Grays plane. one s ing fr tions tic cc down opera time Patok jobs | ous, | Ange over On ship powe nose clim]

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Marc, 1930 figure. But it is comparatively too heavy forward for the nose to rise first, as it should. A man aboard the ship is sent from the forward end aft. The trim is now satisfactory. “C\TAND by for ‘Up ship!’” Ropes are cast off. In the control cabin the Engineer Offi- cer pulls over the indicator of the engine telegraph to ‘Two engines ahead, half speed.” A gong Clangs in the motor gon- dolas. Compressed-air starters spin the motors. They fire. A stream of air shoots back past the elevators or “flippers” that the elevator man is ready to raise, to force up the nose of the ship as soon as it is clear of the ground. The ground crew is tugging at the handrails along the cars to hold back the throb- bing ship. “Up ship!”’ The ground crew literally throws the ship high in the air. We go up nose first. “All engines ahead, cruising!”’ signal the engine telegraphs. We’re off! Almost every week, on the average, the Los Angeles takes the air on training flights, cruis- ing within a 500-mile radius of the Lake- hurst Naval Air Station. Longer trips are made for special purposes, such as the recent flight to participate in the air meet at Cleveland, Ohio. Since we demon- strated hooking on an airplane in flight at that meet, by the way, we have re- peated the stunt successfully nearly every time the ship goes out, and it is getting to be a routine matter. Our longest flight was the trip to Pan- ama and back, more than 2,000 miles each way. We have landed the ship, at sea, at the mast of the tender Patoka and on the deck of the airplane carrier Sara- toga. Two years ago we searched the North Atlantic for signs of the missing Grayson transatlantic plane. We spent all of one summer calibrat- ing radio beacon sta- tions along the Atlan- tic coast from: Boston down past Hatteras, operating part of the time from the tender Patoka as a base. Other jobs have been numer-~ ous, and in all the Los . Angeles has flown well over 100,000 miles. Once in the air, the ship ascends under power by pointing the nose upward, but can climb also by dropping POPULAR SCIENCE MONTHLY Lieut. Commander Charles E. Rosendahl, standing beside the eleva- tor wheel of the Los Angeles, which he commanded for three years. water ballast. She comes down either by flying down or by valving off helium gas. Toggles in rows, small handles shaped like telephone receivers, line the side of the control cabin and govern the release of ballast and of gas. By pulling one of the handles and counting seconds, we esti- mate just how many pounds of water have been dropped from one of the bal- last bags, or by how many pounds the lifting force of one of the gas cells has been decreased. A steersman at the elevator wheel, on the left of the control cabin, guides the ship up or down; another at the forward end steers it to port or starboard. On the side. Once, in a sudden squall, some of the crew were carried, dangling, 500 feet high. 41 The Navy dirigible Los Angeles, “a real ship in every . sense of the word.’’ She has flown more than 100,000 miles. The longest voyage was to Panama and return. board an airship, we use nautical language, for we regard the Los Angeles as a real ship in every sense of the word. A day’s run is even spoken of as the number of “miles steamed,” ignoring the fact that the ship runs on gasoline. A great airship has a sort of personality all its own. An ex- perienced dirigible commander could identify the Los Angeles, the Graf Zeppelin, or the Shen- andoah partly by the way each answers its controls. The shape of the airship makes consider- able difference, as do the size and location of the fins. The Los Angeles responds quickly to outside air disturbances and also to her own controls, partly be- cause her streamlined body is thick in proportion to her length—giving her what we call a “low fineness ratio.’ Moreover, the comparatively shorter and fatter type of construction, followed also in designs for future dirigibles, makes an inherently stronger ship than the Shenangoah, which had a long, slim hull. That slenderness, I think, was the main reason why the Shenandoah, bound for the midwest four years ago, was wrecked when it ran into a line squall near Ava, Ohio. Caught be- tween sharp and conflicting vertical air currents—the most dangerous thing that can happen to any aircraft in the air— her structure broke from unusual aero- dynamic forces too great for it. Several of us, just above the control cabin when the crash came, heard a metallic noise of wrenching girders—and, in the gloom of daybreak, saw the after portion of the ship free itself and fall. Below, through the gap in the struc- ture where the forward car had torn away, we saw the ground dis- appearing rapidly. Shouts disclosed that there were eight men in the rising section. With each man detailed to a station and a duty, we free-ballooned our section of the ship for more than an hour and then descended safely. Many of the men in the other part of the ship, we found, had escaped when it crashed. Of the forty-three men originally aboard, (Continued on page 158)

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Ee eee __, Bureau of Standards Bee 8 a See : WENTY-TWO of America’s foremost scientists and inventors have consented to serve as members of the Committee of Award which will administer PopuLAR ScrENCE MonTHLY’s annual award of $10,000 for the year’s outstanding achievement in science, the creation of which was announced in the February issue. It will be the task of these men to review the year’s activities in American science and invention and to select the accomplishment which, in their judgment, possesses the greatest potentialities as a contribution to the welfare of mankind. The names of many of the Committee are household words in the United States and abroad; others are better known to the world of science than to the general public; all of them are undisputed leaders in their respective fields. In the following series of brief sketches, PopuLar SCIENCE MONTHLY introduces the distinguished members of the Committee to its readers. Dr. CHARLES GREELEY ABBOT is secretary of the Smithsonian Institution, at Washington, D. C., and director of its Astrophysical Observatory and stations in Chile, California, and South Africa. In these observatories exact measure- ments of the sun’s radiation are being made to discover the possible relation between sun spots and the weather, and to determine whether there are recurring cycles of weather. Eventually, experts believe, these observations and others which Dr. Abbot and his staff conducted in the last year at Mt. Wilson Observatory jn California may lead to the practicability of forecasting the POPULAR SCIENCE MONTHLY BURGESS DR. WM. W. CAMPBELL DR. HARVEY N. DAVIS. President, University of President, Stevens Institute The Men Who Will Award Our | $10,000 Prize Marcu, 19 P > of Technology oni Lisl madeaeeeee plete weather a year or more in advance. Dr. Abbot # also responsible for brilliant work in establishing how much of the sun’s heat and light are absorbed by the atmosphere before they reach the earth's surface and in measuring the energy of stars. Dr. SAMUEL ALBURTUS BROWN, distinguished asa physician and surgeon, has been dean of the New York University and Bellevue Hospital Medical College for fifteen years, after serving as a mem ber of the faculty of the institution since 1896 His particular interest has been in connection with the diseases of heart and lungs. He als serves as attending and consulting physician in a number of large hospitals. From 1900 until 1910, he was assistant surgeon in the Twelfth Regi- ment, New York National Guard, and holds the rank of Lieutenant Colonel in the United States Army Reserve. He is past president of the New York Academy of Medicine, a member of the American Medical Association, the Medical Society of the State of New York, and the New York County Medical Society. Dr. GEORGE KIMBALL BurRGEss has been director of the United States Bureau of Standards, at Washington, D. C., since 1923. Before that he was in charge of the Division of Metallurgy. Dr. Burgess has done outstanding work in developing systems of measurement of very high temper- atures. In metallurgical research, his efforts have been concerned among other things with the; development of lightweight alloys for aircraft construction and methods of testing their strength and other properties. He is the author of standard works and textbooks on the subjects of the con- stant of gravitation and experimental physics, and co-author of a book on the measurement of high temperatures. He is the treasurer of the National Academy of Sciences and a member of the foreign service and engineering committees, National Research Council. Dr. WILLIAM WALLACE CAMPBELL is head of the Lick Observatory, Mt. Hamilton, Calif., and president of the University of California. He has done invaluable work in investigating the orbits of comets, their spectra, stars, and nebulae, the motions of stars, and solar eclipses. He has been Silliman lecturer at Yale, William Ellery Hale lecturer of the National Academy of Sciences, and Halley lecturer at Oxford University, England. Marc In re unus forei; Amo Prac Come Nati Dr. Steve N. J. jects tural tion. the mech const has a ing e and « mem Dr. | used Dr. . Geor tion, year: subje volca also i phys temp temp ing n ogist mem tech: tenb Yale Was secre Fellc Scier write cons' char; Uni as a Cher editc eral hold: Johr asso chus pres and and

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1, 19 ot & hing rbed rth’; lasa New dical 1em- (896, tion also in a 910, .egi- . the ates New the lical New ctor , at : he ying Der- ave the ; raft gth ard ‘on- und igh nal ign nal the ind has its the en ale nd id. Marca, 1930 In recognition of his services to astronomy, an unusual number of awards, distinctions, and foreign orders have been bestowed upon him. Among Dr. Campbell’s books are The Elements of Practical Astronomy, The Return of Halley’s Comet, and Stellar Motions. He is a member of the National Academy of Sciences. Dr. Harvey NATHANIEL Davis, president of Stevens Institute of Technology, at Hoboken, N. J., is a recognized expert on such varied sub- jects as turbine engineering, aeronautical struc- tural design, mining engineering, and the prepara- tion of commercial gases. Dr. Davis has served the United States Government as an aeronautical mechanical engineer in the Air Service and as consulting engineer of the Bureau of Mines. He has also been connected, as engineer and consult- ing engineer, with the General Electric Company and other concerns. He is a graduate and former member of the faculty of Harvard University. Dr. Davis is co-author of one of the most widely used textbooks of practical physics. Dr. ARTHUR Louis Day has been director of the Geophysical Laboratory of the Carnegie Institu- tion, at Washington, D. C., for twenty-three years. An authority on such widely divergent subjects as the chemical and physical problems of volcanoes and the production of optical glass, he also is known for his research work in the field of physical phenomena at very high and very low temperatures, the exact measurement of high temperatures, and thermal studies of rock-form- ing minerals. Dr. Day was formerly physical geol- ogist with the United States Geological Survey, a member of the scientific staff of the physio- technical government laboratories in Charlot- tenburg, Germany, and instructor in physics at Yale University. He is past president of the Washington Academy of Sciences, former home secretary of the National Academy of Sciences, a Fellow of the American Academy of Arts and Sciences, and a member of several other societies. Dr. Epwarp Etway FREE, widely known as a writer on scientific subjects, also practices as a consulting engineer and is special lecturer in charge of courses in general science at New York University. During the World War, he served as an officer in the Ordnance Department and Chemical Warfare Service. He has been the editor of scientific journals, and now serves sev- eral publications as scientific adviser. Dr. Free holds the degree of Doctor of Philosophy from Johns Hopkins University and was research associaté of Carnegie Institution and Massa- chusetts Institute of Technology. He is past president of the New York Electrical Society and a member of a number of other engineering and learned societies. Dr. FRANK BALDWIN JEWETT, vice president of the American Telephone and Telegraph Co. POPULAR SCIENCE MONTHLY and president of the Bell Telephone Labora- tories in New York City, has contributed in large measure to the tremendous advance in telephone communication during the last twenty- five years through a succession of inventions and applications of science to electrical com- munication produced and developed by the laboratories under his direction and often with his personal participation. Recipient of the degree of Doctor of Philosophy from Chicago University, Dr. Jewett also holds the honorary degree of Doctor of Science from five great uni- versities and that of Doctor of Engineering from a sixth. He is past president of the American Institute of Electrical Engineering, which be- stowed its Edison Medal upon him for his con- tributions to electrical science. The United States Government has honored him with the Distinguished Service Medal, and the Mikado of Japan with the Order of the Rising Sun. Dr. VERNON LYMAN KELLOGG, one of America’s foremost zoologists and entomologists, permanent secretary of the National Research Council, Washington, D. C., and chairman of its Division of Educational Relations, is equally noted as a philanthropist, humanitarian, educator, and author. During the World War, Dr. Kellogg was assistant to President Hoover, then United States Food Administrator, and later was director in Brussels of the American Commission for Relief in Belgium. He also served with the American Relief Administration in Poland, Russia, and other European countries. Dr. Kellogg has published nearly a score of works and textbooks on bio- logical, zoological, and entomological subjects, and is also the author of books of a more general nature, among them a biography of Herbert Hoover, studies of the effects of war upon the human race, and other works. CHARLES FRANKLIN KETTERING. The inventor of the self-starter, the Delco ignition and lighting sys- tems, and Ethyl gas, Mr. Kettering, president and general director, Research Laboratories, Gene- ral Motors Corporation is (Continued on page 141)

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na I I a lt Sete ee Mea GATT POPULAR SCIENCE MONTHLY The First Please Tire—Invented to By H. C. DAVIS Pneumatic a Boy F ALL the rubber consumed in the United States last year in the manu- facture of tires were made into a single tire of average automobile tread, it would have a diameter of more than forty miles. Lying on the ground, it would encircle 1,400 square miles of ter- ritory, far more than is contained in the state of Rhode Island. Upright, it would tower above the clouds, approximately eight times as high as Mount Everest, the world’s tallest peak. Yet, forty-two years ago, there was but one pair of pneumatic tires in exist- ence. They were on the rear wheels of a tricycle which a small boy, Johnnie Dun- lop, rode through the outskirts of Dublin, Ireland, one moonlight night in Febru- ary, 1888, for an initial test. His father, an inventive veterinary surgeon, had fitted a pair of bulging, air-filled tubes to the wheels in place of the hard rubber strips common in those days, to give Johnnie a faster machine to beat a bigger boy who had defeated him in after-school tricycle races in the People’s Park. It was ten o’clock at night when the work on the new wheel was finished. Unable to wait until morning, young Johnnie Dunlop set out for a speed trial. About eleven o'clock, an eclipse of the moon occurred and he rode home in the dark. In this manner, the first pneumatic tires in Applying the curing rings —one of many steps in modern tire manufacture. history received their road test. In the four decades that have followed, approximately 750,000,000 have been made to cushion the bumps of road travel in all parts of the world. In 1929 nearly eighty-five percent of the rubber con- sumed in the United States went into the making of tires. So vital has rubber be- come to present-day civilization that Thomas A. Edison, at the age of eighty- two, is concentrating upon the problem of obtaining a new source of supply from goldenrod and other native weeds. In tropical countries, seven million acres are devoted to rubber trees in an effort to John Boyd Dunlop, inventor of pneumatic tires, as he appeared shortly before his death in 1921. supply the demand which the pneumatic tire has largely created. Although the _birth- place of the pneumatic tire was Ireland, its in- ventor was not Irish. John Boyd Dunlop was born in a tiny village in Ayrshire, Scotland. At nineteen, he graduated with a degree of veter- inary surgeon from Edin- burgh. A few years later, he emi- grated with his diploma to Dublin and built up an Marcu, 1939 Johnnie Dunlop, son of the inventor, rid. ing the first pneu. matic tired bicycle, extensive practice, concocting new medi- cines and devising original surgical equip- ment to relieve animal suffering. Always of an inventive turn of mind, he spent his leisure for nearly twenty years puzzling over methods of reducing the jolts and vibrations of road travel. As he bumped along in his buggy, making country calls, he planned various forms of spring wheels. Discouraging failures resulted. With characteristic determination, he stuck to his hobby. While using sheet rubber in his surgical work, the idea of air-filled tubes occurred to him. The legend that he used a garden hose for a tire seems to be without foundation. S A first experiment, Dunlop rade a disk of wood. It was sixteen inches in diameter, the same size as the front wheel of the tricycle which his son, Johnnie, rode. To the rim he attached a rubber tube by means of a canvas cover which was tacked to the wood. Taking the disk with its air-filled tire, and the tricycle wheel with its hard rubber one, into the yard, Dunlop asked an assistant which would roll farther. ‘The one with the hard tire, of course,” was the answer. To the assistant’s surprise, the disk with the big, air-filled tire rolled twice as far, struck a gate, and bounded back several feet. When Johnnie saw this result he imme- diately wanted new and faster tires for his tricycle. Working evenings, after the day’s round of treating sick cows and ail- ing horses, his father made two wheels, forming the rims of American elm and fastening the “‘D’’-shaped tires to them by cementing the last of the layers of rub- ber and canvas around the rims. The “nonreturn” valve of the tire was formed by a strip of rubber, placed over the lower end of the supply tube and glued at both ends. When air was pumped in, it forced the middle of the rubber strip inward, allowing the air to enter. When pumping stopped, the air inside forced the rubber strip back over the opening, closing it. The tires were inflated with a football pump and Johnnie set out upon his fa- mous moonlight ride. The next day, his tricycle set a pace that left his rivals far behind. Speed was an important item then. Tricycle and bicycle racing was in vogue. The first motor car had been built only four years before. (Continued on page 166) MaRCH, Pann EM stil prospec norther! They al mother prospec used W vein Wi ounce 0 Gold dr and wil pan the In ne dredges ing twe terial h the cor The di down t two fee bed is « and th thrown shore. | in the 1 For Wi: practic traveli the Si United equipn sists 0 transm instrur

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1930 S, bin i: de | Oehnsrb op | Marcu, 1930 POPULAR SCIENCE MONTHLY 45 PROGRESS AND DISCOVERY Developments in engineering, exploration, and discovery, and news of the world’s progress in science are recorded on these pages. Here are included the interesting features previously presented in “‘Back of the Month’s News.” Panning for Gold—The Old and New Ways EMINDERS of the days of ’49 may still be found today in the dogged prospectors who still haunt the streams of northern California panning for gold. They always hope that they will find the mother lode. The modern methods of prospecting are electrical. Apparatus is used which can detect an underground vein without the need for digging an ounce of earth (P.S.M., Feb. ’29, p. 26). Gold dredges, some of them 200 feet long, and with huge arms spreading 400 feet, pan the precious metal in bulk. In northern California the largest gold dredges in the world are operated. Dur- ing twenty years of excavation more ma- terial has been turned over there than in the construction of the Panama Canal. The dredges plow through virgin soil down to solid rock. They can dig eighty- two feet below the water line. The stream bed is dredged up, passes through filters, and the gravel cleaned of the gold is thrown by the giant conveyor arm to the shore. Rock-crushing plants are installed in the wake of the dredges. Forestry Weather Bureau Travels by Truck EATHER forecasts from almost inaccessible regions will now be practical, it is said, by the use of a new traveling weather bureau recently sent to the Sierra Madre Mountains for the United States Forestry Service. The equipment, housed in a motor truck, con- sists of an elaborate radio receiving and transmitting equipment plus all the usual instruments necessary to measure wind rr t A California deputy fire warden tuning the radio set of the new traveling weather bureau. velocity, humidity, and barometric pres- sure. It will meet the need of obtaining accurate information of weather condi- tions at points threatened by forest fires. Huge X-Ray Tubes Produce Man-Made Radium Rays BATTERY of giant X-ray tubes im- X mersed in a tank of oil and operated at the electric pressure of 1,600,000 volts produced man-made rays like those of ra- dium in a recent demonstration at Wash- ington, D. C. The experiment, performed by the Carnegie Institution, was a step forward in attempts of physicists to break down the atom itself. If this can be done, it may be possible to “‘transmute” one element into another. For this purpose the Carnegie Institu- tion built a huge electric machine, con- sisting of a giant spark coil in an oil tank capable of generating electricity at 5,000,- 000 volts (P. S. M., Jan. ’29, p. 23). Vacuum tubes capable of applying this tremendous voltage, however, remained to be constructed. The new arrangement of X-ray tubes promises a possible way Above: Giant electric gold-panning dredge working a stream in northern California. Left: A prospector of the old school panning by hand. of doing it. Immersing the tubes in oil and shielding one from another permits higher voltages. The rays feed from one tube to the next, an arrangement de- veloped originally by Dr. W. D. Coolidge of the General Electric Company for hooking up cathode ray tubes. Dynamite Blast Travels Four Miles a Second HEN a stick of dynamite goes off, the wave of explosion travels along the cartridge at four miles per second, one of the fastest chemical “reaction” speeds known. Experts at the laboratories of the United States Bureau of Mines at Bruceton, Pa., have been measuring this speed by a clever mechanism called the mettegang (German for “go-between’’) recorder. This measures the time elapsing between the rupture of two wires threaded through the dynamite stick by recording it on a rapidly whirling smoked drum. Excess Humidity Reduces Auto Engine Power POPULAR impression among mo- torists has been that automobile en- gines run better in muggy weather. That the opposite is true is now revealed by recent tests on six-cylinder engines, an- nounced Daniel P. Brooks of the Bureau of Standards of the United States De- partment of Commerce. They have shown that loss of power is directly pro- portional to the excess of moisture in the air. But strangely enough, this does not necessarily mean less power when it is raining, as it is quite possible to have less moisture in the air on a cool rainy day than on a hot, muggy one. The loss of power is proportional to SIP Res. TET penta SO RN SR test NN LAA LS aoe ny et Ni cs pee Pat | RE RT RES CRS ay et '

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8 we Fe A AE i iE Sn ees aes a Ee ea Ses ae 46 the “absolute” humidity, which means the quantity of water vapor in the air at the time of observation. It is usual, however, to find that the loss of power on a muggy day is not especially noticeable, since ex- cessive moisture may be counterbalanced by the effect of air temperature. Another — factor which governs power is the atmos- pheric pressure which [so balances one another that no variation in engine power is observable. Tomatoes, Potatoes Grow on the Same Plant ~~ en f L Fe es od The remarkable ‘‘tomapotato”’ plant, ten feet tall, overtops its creator, Oscar Soderholm. HE “tomapotato,” a new plant de- manding a new name, which produces potatoes at its roots. below the ground and tomatoes on its stalk above the earth, has been developed after twenty years of experiment by Oscar Soderholm, fore- man of a florist’s greenhouses at Worces- ter, Mass. The plant is no freak, but is the demonstration of Soderholm’s theory that, as the roots of the potato plant are stronger than those of the tomato, the combination should produce better to- matoes. His results have proved the soundness of the theory, he claims, for not only does his hybrid grow potatoes but the grafted tomato section attains a height of ten feet, if supported, and bears more fruit than a normal plant. In grafting his queer plant, Soderholm starts by planting a piece of potato, con- taining at least two eyes, in the ground, and planting tomato seeds in a pot. When both have grown to vines about one quarter of an inch in diameter, he makes a cut diagonally across each; then he matches them and ties the grafting to- gether with a thread. Special care must be taken to prevent wilting. Soderholm now plans experiments in grafting cucumbers on Hubbard squash, the roots of the squash being much the stronger of the two. POPULAR SCIENCE MONTHLY New Gas Treatment Ripens Fruit in a Few Hours 'P\HROUGH a process developed in the research laboratory of the United States Department of Agriculture, fruit that would take many days or weeks to ripen on the trees may be ripened in stor- age in only a few hours by treating it with ethylene gas. The treatment may also be used, it is said, to color the fruit and to add to its sweetness. The photograph above shows W. G. Sorber, junior chemist in the laboratory, examining a tray of pears béing gassed. Though brightness in color is no gage of the flavor of fruit, most people seem to prefer more brilliant-toned oranges, for example, to the lighter hued and often tastier variety. With the ethylene treat- ment, fruit may have its color deepened to satisfy the demand for brightness. Moreover, fruit crops may be better controlled. Instead of a crop’s being put on the market all at once, it may be gathered in instalments, and each instal- ment ripened quickly through the artifi- cial process while the remainder con- tinues its slower process of natural ripen- ing on the tree. Largest of Submarines Launched in France HE world’s largest submarine has been launched at Cherbourg, France. The Surcouf, 400 feet of steel naval de- fense, has complete armor protection for all vital parts exposed when running at the surface. This makes her really an armored cruiser, as she can withstand the shells of light quick-firing guns and can return fire. Her displacement is 3,257 tons at the surface and 4,330 tons when submerged. The biggest submarine in the war, the U-139, had a surface dis- placement of 1,930 tons, and 3,050 tons when submerged. The Surcouf can make twenty-five miles per hour, five miles faster than the Humayta, recently built in Italy for Brazil. She will carry four 5.5-inch guns, fourteen tubes which can be used all at the same time, and will have a small sea- plane stored on board. Officers and crew will number 150. The heavy armament of the new battle whale will enable her to sink to a depth of 430 feet, 100 feet deeper than any previ- ous submarine. She will have a fuel ca- pacity to take her 13,000 miles, or half- way round the world, without a stop. Marcu, 1939 Predicts Earth May Grow Rings Like Saturn’s OME day the earth may have rings like Saturn’s. This possibility wags suggested recently by Dr. Harlow Shap- ley, director of the Harvard College Ob. servatory. Saturn’s rings are held to be composed of myriads of tiny moons. The earth’s rings, according to Dr. Shapley, would be formed from fragments of the earth’s moon. It is known to be approaching the earth, because of the gradual slowi down of the solar system. At.a short dis- tance, this expert predicts, the earth’s tidal forces will break it up. According to Dr. Shapley’s figures, this may happen about A. p. 50,000,000,000. Silencer Reduces Noise of Street Drills PARTIALLY noiseless pneumatic drill for tearing up city streets and similar excavation work has been tested in London and found to be successful. It is said to reduce the noise of drilling by _ more than sixty percent. Two methods of noise prevention are used. One is the principle of the silencer, by which the noise of the exhaust air let out of the drill’s air chamber at the end of each stroke is partly prevented, as is done by the silencer on a gun or the muffler on an automobile engine. The second is a redesign of the valves control- ling the motion of the compressed air through the apparatus, so that these valves move through much shorter dis- tances and make less noise when they strike the walls of the cylinder. a 4 weer * Equipped with silencer, this pneumatic road drill is said to reduce noise sixty percent.

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POPULAR SCIENCE MONTHLY 47 Marcu, 1930 Japan’s Three-Way Bridge The unusual triple-span bridge pictured under construction at the left is an attempt of Japanese engineers to relieve traffic con- gestion across a junction of waterways at Kyobashi, the industrial center of Tokio.

A**Big Bertha” of Astronomy. Pointing like a mid- war Krupp gun at the glowing heavens, this new telescope is being used by astronomers at the Obser- vatory of Treptow, Germany, for observation of the sun.

**Theater of the Future.’’ That theater auditoriums soon will be patterned after ancient Greek amphitheaters is the prediction of a German architect, who has embodied his ideas in the model shown above. The domed roof has been skeletonized to show the interior.

Umbrellas Sold by Slot Machine If caught in the rain, Berlin pedestrians now can deposit the equivalent of fifteen cents in a vending machine and pull out an umbrella. The folding emergency umbrella comprises a hood of oiled paper and a handle of wood. First Electric Car Ferry The photo at the left shows the launching of the Saginaw 31, first of a fleet of turbo-electric driven car ferryboats for Great Lakes traffic. Each can carry thirty eighty-ton railway freight cars.

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Ae, als Wee APRESS EA ADCO TO i a = A MAE Fs” amet Ka to 48 New Camera Photographs Eyes to Find Secrets of Vision ECRETS of vision that lie within the retina of the human eye on which, day after day, millions of pictures are photo- graphed successively, are now being in- vestigated by means of a new camera perfected at the famous Zeiss optical works at Jena, Germany. The new Nordenson camera, sliding up and down on its stem, may be adjusted to any height necessary to focus the eyeballs of the subject to be photographed. The subject sits in a chair at one side of a stand on which the apparatus rests, with his chin resting on a padded support from which an arm rises to encircle his face, thus insuring immobility and a standard position for taking the photograph. At the other side of the camera, the operator looks through an eyepiece and manipulates the adjusting screws of the camera until the retina to be taken is in perfect focus. The subject stares into a tubular hood at the front of the camera and while his eye is functioning nor- mally, the photograph is made with an exposure of only one twentieth of a second. Foresees Electric Heat from ‘**Coke Batteries’”’ IANT electric batteries, consuming coke and air and yielding electricity cheaply enough to revolutionize house heating and other branches of practical engineering, are suggested as possibilities by Professor M. deKay Thompson of the Massachusetts Institute of Technology. To heat a house or to generate electricity at present, Professor Thompson says, coal, coke, or some other fuel must be burned in a furnace or under a steam boiler. This is always a wasteful process. Theoretically, he points out, the carbon of the coke might combine directly with the oxygen of the air in a special electric battery, yielding electricity, just as hap- pens when metallic zinc and the solu- tion of chemicals combine in the ordinary dry battery. Such a coke battery might be so efficient as to utilize nearly all the energy of the coke instead of the fourth or less of it that is turned into electricity by ordinary methods. Coke batteries have been constructed, Professor Thompson states, but they work too slowly for practical use. Some possibilities exist, he suggests, of escaping this handicap if inventors can devise suitable solutions and equipment. Evidence of Nerve System Found in Plants ERHAPS plants have nervous sys- tems and hereafter may be treated by neurologists. In experiments with the large cells of the water plant Nitella; Dr. W. J. V. Osterhout, of the Rockefeller Institute, has found evidence of nerve currents similar to those of animal muscle and nerve. His experiments were con- ducted with the aid of an ingenious electrical apparatus which was able to detect minute electrical variations within the cells of the plant. ° POPULAR SCIENCE MONTHLY Below is a remark- able photograph of the retina of a hu- man eye made with the new camera at the right. The dark lines are arteries. Discovery of ‘*Flu’? Germ Awaits Confirmation GERM that looks under the micro- scope like a string of pearls is prob- ably the thing that gives people the “flu,” according to Dr. Isadore S. Falk, Univer- sity of Chicago bacteriologist. He reports that he has isolated the long-sought cause of influenza, and that experiments are already under way to develop vaccines and antitoxins to prevent and cure the disease. The germs, to which only the labora- tory name of “42X” has thus far been given, colonize in clumps. Some of them are rough, some smooth. The rough type is the more virulent, Dr. Falk believes; the smooth ones may be responsible for common colds and sore throats. Announcement of Dr. Falk’s discovery follows a year of work, in which he and thirteen assistants were stricken with influenza. A young woman among these furnished the germs that were finally Dr. Isadore S. Falk, University of Chicago, who reports discovery of the influenza germ. Focusing the eye camera. As the subject stares into the camera, his head is kept stationary by special braces. Marcu, 1939 isolated as responsible for the disease, after about 3,800 other kinds of microbes had been classed as “suspects.” Experi- ments upon monkeys have given hope of immunizing against influenza, and tests upon human beings are scheduled. Meanwhile, caution in accepting the results is advised by the American Med- ical Association, pending confirmation by others in the same field. This is at least the tenth time in five years, it points out, that discovery of the “flu” germ has been announced. Today specific treatment for influenza remains an indefinite future prospect. Such experiments as Dr. Falk’s are always difficult to interpret, it says, although his work is ‘of great interest.” How Much Do You Know About Mechanics? EST your knowledge with these questions, chosen from | hundreds asked by our readers. Answers appear on page 155. 1. Why is it necessary to prime a pump? 2. Which is more powerful— an electric locomotive or a steam locomotive? 3. How would you compute the horsepower that can be developed by a water- fall? 4. How can two electric mo- tors of different sizes de- velop the same power? 5. Why is a vacuum needed to run a steam engine? 6. How is it possible for a man to lift a heavy weight with a chain block? 7. What makes the draft up a chimney? 8. If you double the power in a motor boat will it go twice as fast? 9. What causes the hammer- ing noise in a water pipe when you shut off the water suddenly? en) ¥ Div Han tech

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Marcu, 1930 POPULAR SCIENCE MONTHLY 49 Another Rich Haul of Curious Fishes Found in the Ocean Depths off Bermuda by William Beebe A net full of grotesque creatures from the deep, aglow with lights of many colors, fighting and devouring one another. Top: A black Astronesthes fish, or “Eater of the Stars,’’ pursuing its luminous prey near the surface of t’ e water. Beebe recovering the flag of the Explorers’ Club from a large circular net, after it had been “flown” about a mile and a half below the surface of the sea. Diving at Nonsuch Island, a speck of land off Right: A living specimen of luminous fish, Hamilton, Bermuda. Miss Gloria Hollister, preserved in a labeled bottle, and placed technical associate of the expedition, holds a under the microscope for examination to portable diving helmet used in shallow waters. learn how its deep-sea lamps are lighted. PROGRESS AN D DOTS 6G: O0¥: Boke k: ADRS Sete BO ne ns peepee —— Se inediioa koeeaet x ee Selle nathenaupeauieetn ead ae =n oan ome — " Sse SRE SAO ete oe SS et { «t mm . . —— Anti amen enn pe toning Atal ae lon sale he eet ig eto hora ee he epee eer eR ta rer +e . pion Se EE a oe Nee ~ oe Lo ae ee ™

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50 POPULAR SCIENCE MONTHLY Speeding Electrons Photographed on Metal ICTURES now can be taken on plates of solid metal, instead of film. A way to develop pictures made on gold and other metals is the recent discovery of Dr. P. H. Carr, Cornell University. The new method of photography with- out light is not intended for taking snap- shots of the baby, or the suburban home. Instead, it pictures the track of flying electrons—those tiny electric charges most familiar as the invisible streams of power that radiate from a radio tube’s hot filament. The pictures reveal vertical lines, slim where high-powered beams struck and broad for lower power, and may lead to important discoveries of the ways that electrons behave. Hitherto ordinary photographic plates, usable only in the dark, have been pressed into service for studying electrons’ tracks, but the new plates record in broad daylight. They are more sensitive than film for electrons flying at comparatively low speed and nearly as sensitive at high speeds. The discovery was made by chance. To produce X-rays an electron beam bombards a metal target in an X-ray tube. Dr. Carr, working under the direc- tion of Dr. F. K. Richtmeyer, Cornell physicist, noticed the pitted condition of an X-ray target after use and wondered whether any traces of such a bombard- ment could be revealed by “developing,” even before visible rough spots appeared. He shot electrons from a vacuum tube at a polished gold plate and found he could bring out the impression made by the electrons with mercury vapor. Silver and copper plates revealed a recognizable picture when “developed” with iodine, and zinc plates with hydrochloric acid. Alcohol from Natural Gas RAIN alcohol from natural gas is the latest feat of manufacturing chem- ists. It has been developed by the Union Carbide Company by “cracking” the gas into ethylene (a new anesthetic of great possibilities) and converting ethylene into ethyl (grain) alcohol by a new method of combining ethylene with water. Dr. P. H. Carr, Cornell graduate student, and the vacuum tube apparatus with which he photographed electrons. 2 vol he Below: Photographs of the tracks of flying electrons made on plates of polished metal. The small parallel lines are the impressions left by the novel bombardment. Automatic Chemist Saves Work in Laboratory OW comes the “‘automatic chemist” —a device that relieves the chemist of one of the most tedious parts of making an analysis. As recently demonstrated in New York City, the automaton measures either the acidity or alkalinity of a solu- tion, or the amount of certain ingredients in it. When the measurement is com- pleted it rings a bell and lights a red light. This fundamental operation, known to chemists as “titration,” is important in every application of chemistry, from making shoe leather to the testing of a city’s water supply. A careful titration may take half an hour of a chemist’s time, but the mechanical chemist requires no attention after the start. A glass beaker contains a measured quantity of the transparent solution under test. A few drops of a solution such as phenolphthalein, which is red in the pres- ence of alkali and colorless in acid, is Demonstrating automaton which controls a chemical experiment without human aid. Marcu, 1939 . added. If it turns a vivid pink, indicating that the solution in the beaker is alkaline, acid from a graduated tube is allowed to drip into the beaker. A beam of light from a lantern shines through the beaker while the test is in progress, falling upon a light-sensitive electric cell opposite. When the solution suddenly turns white again at the addition of one additional drop of acid, the “electric eye” turns off the acid and rings the bell. The amount of acid required to neutralize the alkali may then be read from the graduated tube, giv- ing an index of the original solution’s alkalinity. The operation may be reversed, adding alkali instead, when acid solutions are to be tested. Since the human eye is a poor judge of the exact moment of color change in any such test, the automatic chemist is likely to be more accurate than a man. Poor Food, Not High Life, the Cause of Ills N A recent report to the American Medical Association comparing the diets and diseases of 501 selected patients, Dr. Lovell Langstroth, of San Francisco, finds that the ordinary “business man’s” or “society woman’s” diseases are due not to fast living but to bad food. Foods are either “protective” or “nonpro- tective,” he says. Protective foods are those containing plenty of vitamins, minerals, and other principals believed to protect the body and keep it in working order. Such foods are eggs, milk, fruit, lettuce, and vegetables. But these make up only twelve percent of the American’s diet, which is too little, Dr. Langstroth declares. Among the nonprotective foods, of which Americans partake altogether too freely, he finds, are sugar, cream, may- onnaise, potatoes, and sweet desserts. Dr. Langstroth lays arthritis, heart disease, high blood pressure, chronic stomach trouble, and other diseases at the door of a nonprotective diet. An Artificial North Light for Color Matching N THE past artists have coveted the daylight from the northern sky for matching their colors, believing it the best possible. But A. H. Taylor, physicist of the National Lamp Works at Cleveland, Ohio, recently told the Illuminating Engineering Society that northern sky- light varies in intensity from day to day and even from hour to hour. And he added that the best light anyway for color matching was the white light correspond- ing to noon sunlight on a clear summer day. But this light can only be had for a short time during the day* in the right season and the right weather. Taylor suggests an artificial solution of the difficulty. Substitute, he says, an artificial sun consisting of a tungsten incandescent lamp with color filters. This artificial north skylight can be produced at a cost three times that necessary for the production of white light. In using it, however, artists should bear in mind that it is of a bluish quality and makes pink, lavender, magenta, and purple appear bluer than they should, while it tones down yellow, orange, and red. MARCH, For meas stree tests Thes To aid tures a chine Into it and th the sou impose mem A. WL?

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Marcu, 1930 POPULAR SCIENCE MONTHLY ft Soe ee **Diamonds from Sugar.”’ By subjecting ordinary table sugar to enormous heat and pressure in the laboratory, Prof. J. M. Hershey, of McPherson College, Kansas, claims to have produced diamonds the size of a grain of sand. Larger artifi- cial gems are possible, he says. He is shown with his apparatus. + Rca SR aed as gee tae Do a = « i ~ < a emde Se Measuring New York City Noises DEE SOP eN ST, eA Ali A oS adie For several months a truck carrying delicate instruments to Pct : measure the intensity of noises has been roaming New York ee streets gathering evidence in the city’s antinoise campaizn ‘ Pi Hs (P. S. M., Jan. ’30, p. 17). Health officials are seen here making oma tests with the instruments, which give visible and audible records. These serve for comparisons between various sections of the city. on.

2 4 | | f 3 |

Bucket Dredge Cleans Canal This huge dredging machine recently advanced along the Landwehr Canal, Berlin, Germany, clearing the water- way of an accumulation of debris and sediment. The buckets, rising from the bottom, dumped their load into a tank; the water drained out, leaving the sediment.

int , 4 - i { ; iy = , Bs a 7 t : d t m2 ES Seen te NCR i em etili iy ra “5 Fitting Voices to Faces To aid movie film editors to synchronize pic- tures and sounds for the talkies, a new ma- chine called ‘“‘moviola’? has been devised. Into it the editor feeds the picture film (left) and the sound film (right). By listening to the sounds and watching the picture he super- imposes one record upon the other (center).

An Electrical Garden To speed the growth of plants in a test gar- den at Stockholm, Sweden, electric heat is applied to the soil. Beneath the beds are laid lines of resistance wires about a foot apart, as shown at the right. . These are sheathed with brick and then covered with a layer of soil a few inches in thickness. rc cae A LE EET i FTE EEE me ner mice P & 6:¢ BE 3's AND D3 -S C-O.-V-E-R-Y

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= Ste goa aioe Setting th in Aviation Around the Air Circuit for a 5,000-Mile Record—New Amphibians for Forty Passengers—Other Flying Progress LL distance records for airplane flight apparently have fallen, re- cently, with the trip of Dieudonne Costes, French aviator, and his companion, Paul Codos, over a closed circuit in France. Although the mark actually attained has not been checked officially at this writing, preliminary esti- mates place it close to 5,015 miles. This exceeds all records for either a flight around a measured course or a straight- away flight from point to point. To achieve it, the flyers winged their way for fifty-two hours over a triangular course of about 206 miles. The distance covered was a tribute to the cruising radius of the modern airplane. Only a short time ago Costes and an- other French flyer, M. J. Bellonte, smashed all straightaway distance records by a flight from Paris to Manchuria. The Aero Club of France gives the official dis- tance of this flight as 4,912.01 miles. Safety Contest Winner OLE survivor among the fifteen planes submitted for the Daniel Guggen- heim Safe Aircraft Contest, the Curtiss Tanager, a slotted-wing cabin biplane, recently won the grand prize of $100,000. No finals were necessary in the contest, Designed as an au e Pace tomatic stabilizer, this device combines a vane and pendulum mechanism POPULAR SCIENCE MONTHLY Marca, 1939 because this was the only machine to pass the eighteen exacting tests designed to find a “foolproof” airplane. Besides the slotted wing, which is a small auxiliary wing serving to minimize danger from stalls and spins, the machine has another radical feature in what are called “full floating” ail- erons or balancing flaps. These are unsupported, tilt- ing flaps placed at the tips of the lower wings, and are said to give increased control. The air- plane carries three passengers. A dupli- cate of this airplane is expected to be developed for commercial production. 40-Passenger Amphibians AST month Popular SCIENCE MonrtTHLy described a fourteen-pas- senger amphibian plane, at that time the largest plane in the world that could alight either on land or water. Now construction is announced of two forty-one-passenger Sikorsky amphibian planes, by far the largest amphibians in the world and even among flying boats comparable only to the Dornier giant 4 said to govern a plane’s controls to restore balance. Inventor is O. W. Greene of Elyria, O. (left). Testing the use of enormous shock-absorbing balloon tires ona big plane at Los Angeles. Only seven pounds pressure required. aah Ree DO-X in size. When placed in service next December, they will inaugurate twenty-four-hour service between New York City and Cristobal, Canal Zone. Known as the S-40, the new type has a wing spread of 114 feet. Four motors will drive the huge ship at a cruising speed of 108 miles an hour. The power plant has a total of 2,300 horsepower. Passengers traveling from New York to Cristobal will fly by night from New York to Miami in small planes, where they will board the giant S-40’s in the morning. Sitting in comfortable armchairs, they will be whisked over the 1,200-mile jump across the Caribbean Sea to Cristobal, stopping at Kingston, Jamaica, or on the Honduras coast for refueling. Adding 75 Feet to R-101 N EXTRAORDINARY surgical op- eration upon Britain’s recently-com- pleted airship, the R-101, is to add a seventy-five-foot piece to her midsection. The great hull will be cut in two and the extra section grafted in, it is announced. This action follows reports that the lifting capacity of the R-101 proved disappoint- ing in trial flights. Addition of 500,000 cubic feet of gas capacity in the new cell will bring her total bulk to 5,500,000 cubic feet, making her the largest in the world by an in- creased margin. It will add six tons to the useful load that can be carried. When the operation is completed the airship will be about 800 feet long. The novel oil-burning motors of the R-101 may also be replaced with lighter motors. With the recent launching of the R-100 on its first trial flight after a delay of many weeks, Britain has the two largest airships in (Continued on page 54) Mart Abdov of tl at he ton, of P: vas- an i saloc The and seve mids

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| 30 - Marcu, 1930 POPULAR SCIENCE MONTHLY 53 Close-Up Views of the World’s Newest Dirigibles | ——————

ting out water ballast as she approaches the mooring mast at Cardington at the end of her recent maiden voyage. This great liner is the first three-deck airship, having two upper floors for the passengers } and a lower one for the crew. i PMs Above is a striking close-up view 4 of the British dirigible R-101 j at her mooring mast at Carding- , ton, England, showing members } of Parliament crossing the can- 7 \ vas-sided gangway. Opposite is a an interior view of the spacious saloon lounge of the dirigible. The R-101 is to be cut in half and enlarged by adding a seventy-five-foot piece to her midsection, increasing her lift. , “4 by e ft e 4 i} NV F a : , l ; f : ia : . < The new British passenger dir- ; | igible R-100 is seen above let- : _ ~

Walking the Slate all-metal diri- gible City of Glendale out of its hangar at Glendale, Calif., for a trial flight. An accident prevented the take-off. The sun, beating on the metal envelope, expanded the gas. A safety valve stuck and a seam burst near the ship’s top.

One of the innovations of the Slate airship is an elevator for lowering and raising passengers. At the left the ground crew is seen placing the elevator in its shaft +g oy ‘ beneath the cabin. Another novel Capt. Thomas Slate, inventor of the all-metal feature is a blower used instead airship, standing beside a small motor gener- of a propeller to drive the craft. ator which supplies current for the elevator.

pa | i i if 4 : i

hat. ik tien Pat

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wae ————— pels pis > ge Curate fe wig POPULAR SCIENCE MONTHLY Working on the landing wheels, the new airplane brake at the left is said to stop the heaviest plane within 300 feet. Hydraulic pressure forces a stationary plate against a disk attached to the land- ing wheel. In the illustration the wheel is removed so as to show the mechanism. Racing against death in a thousand-foot plunge, an instructor and student landed in this burning plane recently at Roosevelt Field, N. Y. Both jumped to safety before camera clicked. the world. The 709-foot R-100 is the first three-deck airship, using the two upper floors for passengers and the low- er one for the crew. Duralumin gird- ers of new tubular design for the frame- work of the hull can be removed or re- placed with ease. In other airships it is necessary to cut out a damaged piece and rivet a new one in. For the first time, also, a method has been developed in the R-100 for changing the engines while the ship is at the mooring mast. The first long flight of the new ship is expected to be to Canada. Automobile Engine Drives Plane AN AUTOMOBILE en- gine drove an airplane successfully in a recent test at Dayton, O. The air-cooled engine, which had driven a car of standard make to the flying field, was removed from the automobile and _ trans- ferred to the airplane. It supplied adequate power dur- ing a flight that asted sev- eral hours. Engineers view the test as significant because of the pos- sibility that airplane and auto motors may become more or less identical in design with engineering advances. Ac- cording to H. H. Franklin, motor car manufacturer, there is no reason why a motor should not be made that will function equally well in airplane or car. Auto- mobiles may be the principal gainers, the lightweight, effi- cient motor developed for aviation being generally regarded as the highest engi- neering development of gasoline engines. Next—Beryllium Planes? ILL airships and airplanes of beryl- lium be next? That duralumin, lightweight alloy of aluminum long used for building dirigibles, may have a future rival in this little-known and costly metal And then it crashed. This unusual photo was taken an instant before the left wing of a plane hit’the ground at Mascot Airdrome, Sydney, Australia. Marcu, 1930 is the suggestion of the United States Bureau of Mines in a recent report. The National Advisory Committee for Aero- nautics is planning to test the use of beryllium for airplane construction, the report adds. Beryllium, also known as glucinum, is one of the very light metals. It is q third lighter than aluminum and dur- alumin, which is an alloy of aluminum and magnesium, with small quantities of copper and manganese, f about the same weight of aluminum. In addition, beryllium is exceptionally hard and strong, an unusual combina- tion with lightness. Should its present almost prohibitive cost of about $200 a pound be reduced by quantity produc- tion, some experts see it as the new and logical light metal for aviation use. At present its application has mainly been restricted to such odd jobs as making parts of X-ray apparatus and the electrodes that are used in neon advertising signs. New Curved Radio Beam LLOWING a curved radio beam home is the newest way for an airplane flying in fog to land. It was demonstrated the other day at Wash- ington, D. C., with the aid of apparatus perfected by the United States Bureau of Standards. In this method a beam transmitter is buried, flush with the ground, in the center of a landing field. The beam pro- jects nearly horizontally across the field, slanting slightly upward for a distance of about two miles; then it curves sharply upward into the sky. An approaching air- man is informed by radiophone in which direction the beam is pointing. He circles the landing field until he picks it up through dials on his instrument board; the beam is about twenty feet wide. Then the pilot simply flies down along the beam and safely onto the field. Two vertical beams near the end, at fixed dis- tances from the field’s center, give the pilot his altitude and tell him when to pull back his control stick for landing his plane safely. Mail Pilot Flies Million Miles ORE than a million miles covered in the air is the extraordinary record of E. Hamilton Lee, thirty-five- year-old air mail pilot on the western transcontinental route. In all that distance, he has never had a major accident. Since he began piloting, in 1913, he has flown between 10,000 and 12,000 hours in forty-five different makes of airplanes. His career, which started with barnstorming, includes among other exploits the successful dropping of food to eleven ice-bound lum- berjacks marooned on South Fox Island, in Lake Michigan, after five other pilots had failed in the attempt. MaRcH night might of sch erecte Parde world On aerial one oO ever | twelv built, grave WI the d again huge the v on ro peril ing t Me the | after the 1 unde light: 615,( crete the | more Con mixe a h dow: dam spou “ele O achi by t cubi sing

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Marcu, 1930 POPULAR SCIENCE MONTHLY The Pardee Dam under construction. Con- crete from four mixers at the top of the steel tower poured down to the dam through chutes. At left: The completed dam, 358 feet high, finished a year and a half ahead of schedule. Build Great Dam in Record Time Workmen Labor Night and Day to Save California Cities from a Water Famine HEN nine cities in the East Bay region of California were faced with a water famine, engineers working day and night completed one of the world’s mightiest dams a year and a half ahead ef schedule. Unusual high-speed methods erected this 358-foot-high structure, the Pardee Dam on the Mokelumne River, in world’s record time. One of the builders suggested that an aerial tramway three and a half miles long, one of the largest heavy-duty cableways ever projected, would save constructing a twelve-mile railroad. The cableway was built, and carried 250 tons of sand and gravel hourly for twenty months. When unlooked-for floods threatened the dam while the engineers were racing against time to complete it, they built a huge flume to carry the flood waters and the work went on. Workmen suspended on ropes, like monkeys on strings, dangled perilously above the swirl- ing torrents. Most of the concrete for the dam went into place after dark. Records fell as the racing workmen toiled under the glare of flood- lights. In relays they placed 615,000 cubic yards of con- crete—enough to prolong the Washington Monument more than a mile skyward. Concrete from four giant mixers, hoisted to the top of a high steel tower, shot down to the bulwarks of the dam through chutes and spouts familiarly known as “elephant trunks.” One of the new records achieved was the placing, by this method, of 514,000 cubic yards of concrete in a single year. The whole dam, By EARLE DUFFY together with a 20,000-horsepower power house, was completed just two years after construction began in the rock-bound gorge. ° The completed struc- ture forms a dam known as the curved gravity type. Its height from the river bed is not far short of that of the 385-foot-high Pacoi- ma Canyon dam in south- ern California, the highest dam in the world at this writing. Under the glare of powerful floodlights workmen toiled through the night placing the concrete. Preparations for this work were made in daytime. This three-and-a-half-mile aerial tramway saved the construction of a railway twelve miles long. Other dimensions of the new dam are equally im- pressive. Its curved crest measures a quarter of a mile long from one side of the gorge to the other. The dam backs up a lake of 222,000 acre feet; that is, enough water to cover the whole District of Colum- bia about five feet deep. Through the 847-foot-long spillway, a cataract of water will pour in flood times with more than half the volume that goes over Niagara Falls. 1 Bhs eee Parca eae ee ot apie att AO pod err tf neers pani ny est tiiaahisaatininireitageibie a

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The wolf. Science has discovered a common ancestor of this ferocious animal and the police dog on the opposite page. ural EVENTY-NINE breeds of dogs, among them rare and little-known varieties, will constitute soon the greatest dog show on earth, at the Peabody Museum of Natural History in New Haven, Conn. It will be a show with- out a-bark, for the novel collection is not of living dogs. Instead, skulls, skeletons, and complete mounted specimens of all present-day breeds recognized by the American Kennel Club, and their wild ancestors, will be there. The purpose of the unique exhibit is to enable future generations of students and scientists—perhaps 2,000 years hence— to compare the dogs of their day with those of the twentieth century. Already skulls of the Irish wolfhound, the New- foundland, and entire skeletons of the cocker spaniel, French bulldog, and pedigreed bloodhound, with their skins for mounting, have been received. A prized specimen is that of Togo, the Alaskan dog that carried diphtheria serum to Nome, Alaska. Under the care of Leon F. Whitney, authority on genetics, or the laws of inheritance, the exhibits will attempt to summarize present knowl- edge of how, through evolution, all these highly modified breeds came into exist- ence. Only recently has such a task become possible at all. Recent scientific work has solved, in part at least, many mysteries about the dog and its history. What possible relation can there be, for example, between the barrel-shaped bulldog and the slim, fleet grayhound, or between the midget Chihuahua and the lumbering Great Dane? How did such breeds come into being, and are certain ones dying out? Is the German police dog, or shepherd dog, almost totally wolf? Is the dog descended from the wolf? And when, and where, did the first dog originate? Not until the beginning of the present century could geologists and zoologists commence to answer questions such as these, despite the knowledge of evolution POPULAR SCIENCE MONTHLY Once By acquired in the century past. It has been a slow yet thrilling task. A ran- dom specimen, a skull or a few fragments of bones dug up in some odd corner of the earth, has often supplied a missing chapter of the story. A skull is a treasured find; for, accord- ing to experts of the American Museum of Nat- History, it shows most strikingly the march of evolution to higher types. Thus, within the last few years, the story of the dog and its forefathers has been shorn of nearly all its mysteries. Back in that remote epoch known as A group of coyotes at night. These are more wolves than dogs, but they belong to the same family tree. the Tertiary geologic age, three million years before men were building sky- scrapers and flying the Atlantic in air- planes, the story of the dog begins. All the evidence indicates that over the vast wastes of Europe and Asia, in that day, ranged the Creodontes, the four-footed heavy-set ancestors of all the carnivorous animals known today. Before the Ter- tiary age had reached its halfway mark, the only family of these destined to survive until the present day had ap- peared—strange creatures that rolled into | one the racial characteristics of the dog, the bear, and the zibet, or Bengal civet cat. Born of the fierce struggle for existence, Marca, 1939 Was Your Dog a Wolf? STEPHEN SHERMAN distinct types developed among these animals. Toward the end of the great Tertiary age there appeared a new race of four-footers—the family, or genus Canis, as it is known to science, in other words the “genuine dog.” HIS was the ancestor of all dogs, the primitive root from which all dog pedi- grees of the present day have sprung. Exactly what he was like will probably never be known unless some lucky ex- plorer discovers his fossilized skeleton— yet his ghost looms out of the past, a real though intangible presence. ~ One of the many species of the original Canis in particular reached a high state of development. He was Canis lupus— Latin for “wolf dog’—the Adam or first parent of all dogs of today, excepting a few wild varieties. And—it is inescap- able—he was also the parent of the mod- ern wolf. Probably Lupus himself looked more like a wolf than a dog, though this cannot be more than speculation. At any rate, the answer to the question, “‘Are dogs descended from wolves?” is “yes,” with reservations. The modern dog is descended from an ancient an- cestor that may be called a wolf or a dog with equal justification. It would be no more accurate to say that all present-day dogs have wolf blood than to say that human beings have monkey blood, even when common ancestry of the last is admitted. In both cases the common an- cestor is so remote, and the changes through the ages so marked, that by now the strains are separate. That is the story of the dog’s his- tory as it is summed up by the great German authorities, Studer and Stephanitz, and specialists at the American Museum of Natural History hold it to be a true one. Domestic or tame dogs, and wolves (including coyotes, or prairie wolves), are not the only branches of the family tree Skeleton of a prehistoric wolf, Canis dirus, unearthed recently from a California tar pit. that st Canis. the mal spoon-s the ding or fore: in sout cestors dants 1 the ‘‘L South J N hi just r Troues near Q discove not loo of its | was. * plied a could | of Can ing off Tertia1 A fe named found than a Austra indisc1 this is offshoc popula Kno lution, the w into e thern “paria Studer! northe wild « reddis odd v carrie: peopl Today Herbe skel

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f ae Marcu, 1930 Science Traces the Shepherd Dog, Wolfhound, Spaniel, Bulldog, and All’ the Others, Back to a Common Ancestor Which Lived Millions of Years Ago, and Discovers Interesting Facts to Explain Why a Great Dane Differs from a Pekinese that starts with the ancient family of Canis. At this early time branched off the marten dog and the ‘‘Otocyon,” with spoon-shaped ears; also wild dogs like the dingo of Australia and the “‘Icticyon,” or forest dog. Distinct breeds appeared in southern Asia and in Siberia, the an- cestors of those of today. Other descen- dants were the jackal, the Alpine dog, the ‘‘Lyacon” or hyena dog, and the South American species known as Thous. N the so-called wild dogs, in fact, hinges the scientific proof of the story just recounted. An explorer named Trouessart, hunting early in the 1900’s near Quito in the South American Andes, discovered a curious wild creature. It did not look like a dog, yet the arrangement of its teeth showed that it undoubtedly was. This dog, the Jcticyon rivetti, sup- plied a “missing link” in a pedigree that could be traced right back to the family of Canis. Thus it confirmed the branch- ing off of dog families as long ago as the Tertiary geologic age. A few years ago, an English explorer named Tanning reported that he had found a new kind of wild dog no bigger than a rat in the fastnesses of western Australia—a strange creature that fed indiscriminately on lizards and bugs. If this is an authentic dog, it is one more offshoot of the single ancestor that populated the world with dogs and wolves. Knowing the story of the dog’s evo- lution, it is possible to reconstruct the way that the diverse breeds came into existence. Grayhounds of the sou- thern Mediterranean, Tibetan and “pariah” dogs, and dingoes are traced by Studer to a single common ancestor in northern Europe and Asia. Of these, the wild dingo, bushy-tailed, wolf-faced, and reddish-brown, reached Australia in an odd way. It is supposed to have been carried there, tamed, by a prehistoric people who were driven out of Europe. Today there are savage tribes along the Herbert River, in northern Australia, who A remarkable action mounting of a wolfhound skeleton. Compare it with that of the wolf. * POPULAR SCIENCE MONTHLY Atypical German shepherd dog, commonly known as a police dog. It is of pure breed with no modern wolf blood in its veins. ee ek The bulldog, above,”and the wolfhound, be- low, run in the same way. Note how the hind legs pass outside the front legs in each case, accord the dingo an important place in the family. The dingoes, in Australia, returned to wildness. The dog ancestor of northern Europe and Asia lived on, alongside the wolf, during and after the Glacial Period. This dog, Studer suggests, was tamed— and from it was bred thé race of larger domestic dogs such as the St. Bernard and Great Dane. Contemporary with this ancestor lived a dwarfed wild dog, from which the moorland dog was bred. From the moorland dog, which spread all over Europe, must be descended the Spitz, the pinscher, and the English terrier. It also played a part in the breeding of the dogs of the high North, the Lapland and Iceland dogs and the Finland bird dog. 57 And what of the German shepherd dog, or “police dog” as he has been known since the war, perhaps the dog most talked of today? The bones of his an- cestor, the Bronze Age dog, have been unearthed among relics of this period which date from 2500 to 1800 B. c., at Olmutz, in Moravia. A similar skeleton found on the estate of a Russian prince near Moscow confirms the fact that this dog came from the North, the region where the merciless struggle for existence produced the high dog types that spread over the world. Its skull proportions stamp it as the immediate ancestor of the present-day police dog. The taming of this dog probably typifies that of most other dogs through- out history. He came during the night watches to the farms and villages, to scratch among the refuse heaps. Warm fireplaces lured him to human associa- tion, and food shared with the hungry dog banished his misgivings and made him glad to forsake the precarious life of the wilderness. ONTRARY to popular opinion, the shepherd or police dog has not been crossed with the wolf, and has none of the qualities of such a mongrel. A dog- wolf mongrel is unreliable, sly, treacher- ous. An English enthusiast named Brooke, who kept and constantly ob- serves all sorts of wild dogs—wolves, dingoes, hyenas—said he would rather deal with a wild old wolf than with a wolf mongrel. The German authority Steph- anitz, after making many crossings, agrees. Fortunately the dog of the Bronze Age, the first comrade of the prehistoric shepherds, exists today in pure-bred descendants. Today the shepherd dog is the center of attention among scientists who are anxious to find what part physiology plays in dog evolution. Dr. Charles R. Stockard, professor of anatomy at Cor- nell University, singles out the shepherd dog as the one most nearly resembling the normal wolf dog, or probable ancestor of most of the (Continued on page 144) A NS, te ae i Ti, Mp A ISIE aa RRO aia We a bn: seat tr APRN ee te th i ete eB ail te yd A tay” i itt tent

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POPULAR SCIENCE MONTHLY Drying Machinery ‘Triples Crops MARcH, 1939 MARCH, 19 The heating plant. foot blower sends it through the drying tunnel. ACHINE methods applied to agriculture are growing three crops of grain a year where only one grew before. Already well past the experimental stage, a device that dries green crops artificially by coal fires and powerful ventilating fans is being used successfully on five large farms in the United States. It is said to permit mass production of agricultural products on a scale never before achieved. Here furnaces produce hot air at 300 degrees, and a twenty- Anthracite coal is the fuel used. teins and in nitrogen content, together with other elements of value to such animals as milk cows. Wheat, rye, oats, barley, and soy beans are among the crops handled, at the rate of two tons an hour. A thousand pounds of coal will dry a ton of the finished product. Extensive use of the novel system might have other important consequences. By planting three crops a year, for ex- ample, the farmer might conquer the vex- Mass Production on Farms Now Made Practicable by Harvesting Unripe Grain By JOHN E. LODGE is estimated in Government figures to cost America one sixteenth of an inch of her best soil every year—threatening to denude it within a century. Planting three crops a year would bind together the soil and in this manner protect it from washouts. plan passed the experimental stage, as first described in this maga- zine (P.S.M., Oct. ’27, p. 32), the machine method has now been operated success- fully on a commercial scale. Feed for a herd of 2,500 cows is dried by this ma- chine at a large Plainsboro, N. J., dairy farm, where it has been in operation for three years. Last year another machine dried soy bean hay from April to Septem- ber at a Thibodaux, La., farm, following this with native grasses in October, and it is scheduled to fill in the time to the next soy bean harvest with alfalfa. One Waco, Texas, farmer found it profitable When crops are cut green other crops ing problem of soil erosion. This erosion, to use the machine. Several other ma- ice that may be planted immediately. The device due to heavy rains which fall upon open, chines have been operated on a commer- I was that makes this possible, an artificial plowed-up fields and carry away the soil, cial scale by the inventor. Bulgaria dryer for alfalfa, wheat, The drying plants can be operated 200 We wet and other products, was days a year, regardless of the weather, on British invented by Arthur J. a 600-acre tract, tripling its usual output. lines. T Mason, Chicago industrial The system is not adapted to small farms, lower th engineer. It is said to make as one of at least 400 acres is required to boring rf possible the harvesting of keep it operating steadily from the first 10,000 f excellent hay in May and to the last cutting. However, a group of the sun: of cowpeas in November farmers could get together and rent or in white when conventional farm- buy such a plant and use it profitably on ing laye ing has long been through a coéperative basis. were air for the year. of the n Trucks deliver green I do cut crops to the drying swervec machine. ‘The alfalfa or depress: other material is torn to and—it individual strandsand down d: formed into a mattress sucked nine feet wide and nearly stick j a foot thick. It enters a The shi drying tunnel 150 feet long. Hot air from rearing twenty-four furnaces robs it of its moisture Comple during the slow trip through. Then the went | cured, bright green mattress of hay is torn wires t apart and shot by an air blast to the we col barn. One hour after the alfalfa is ahead cut it is cured, ground to meal, and filled tl stored away. struck Another link in the swift process fire ho: is a fleet of mowing machines that of hai cut the alfalfa, chop it into foot crashet lengths, and deliver it to trucks mov- Figh ing alongside. One man drives the crouch mower, and another the truck. times As a result: of the drying process, the towarc product is claimed actually to have an en- This machine receives green cut alfalfa from trucks, forms it into mattresses, and sends it into the dry- and a hanced food value in flesh-building pro- ing tunnel. Above: A truck runs beside the mower gathering the harvest, which] is cured in an hour. flashec

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ns <; in

Marcu, 1930

POPULAR SCIENCE MONTHLY 59 Jordanoff points cut how air tube of bank and turp indicator now is placed near engine for warmth, to prevent clogging by ice or snow. Beating the Weather in the Air What a Veteran Pilot Has Learned from Encounters with Storm and Fog During Sixteen Years of Flying HEN I think of flying weather at its worst, I think of a 9,000-foot plunge through dark- ness filled with ripping bullets of ice that I once experienced. I was up with a photographer in a Bulgarian army plane during the war. We were ordered to take pictures of British movements behind the Saloniki lines. The sky was ugly. The ceiling was lower than the jagged cliffs of the neigh- boring mountains when we took off. At 10,000 feet, our Albatross nosed out into the sunshine. We saw shrapnel. bursting in white puffs above the roll- ing layers of clouds. Gunners were aiming at us by the sound of the motor. I dodged the gunfire, swerved into a saddle-shaped depression between two clouds, and—it happened. A gigantic down draft caught the ship and sucked it into the clouds. The stick jerked from my hand. The ship turned over and over, rearing and plunging as it fell. Completely out of control, it went down with screaming wires through clouds so black we could barely see a foot ahead of us. Rain and hail filled the darkness. The water struck as though shot from a fire hose and the white bullets of hail ripped along the fuselage and crashed against the wings. Fighting for control of the ship, I crouched behind the windshield, at times plunging two miles a minute toward the crags below. We might strike and never see them. A queer thought flashed into my head. I wondered if I By ASSEN JORDANOFF would know I was dead after we hit. Then a miracle happened. Like a cannon ball, the Albatross shot out of the clouds below the tops of the mountains. It was in a tight spiral, diving parallel to the mountain slope less than 100 feet away. Had it come out headed the other way, nothing could have saved us. The altim- eter showed less than 1,000 feet when I got her leveled off. We had fallen nearly two miles. After I landed at the flying field, I found the trailing edge of one wing almost in shreds from the strain of the terrific dive and the pounding hail.

NE Above the lee slope of a moun- tain such as this a flyer often en- counters a strong downward air current, or ,“‘settle-draft.” The diagram at the right pic- tures the various sources of “bumps” in flying caused by rising currents of warm air, and of “holes” in the air produced by cool downward air currents.

SHOWING COMPARATIVE J FERENCE iN VARIOUS

Our faces were swollen and for days they were pitted, as though pock-marked, where the balls of ice had struck. Around clouds there are always rising and falling air currents. A cloud is formed by a warm, moist current rising into cooler regions of the upper atmos- phere. When a flyer passes under a large cloud on a hot day he gets a bump. Under all such clouds are strong rising currents. Glider flyers in Germany use them to soar for miles across country in a new sport they call “cloud flying.” Starting from a hilltop, they glide to a place under a cloud and are carried upward by the column of rising air. Then they soar on to the next rising column, in this way progressing for long distances. Within the great mountainlike masses of a cumulus cloud, drifting in sum- mer skies, there are rising cur- rents under every “peak” and descending currents under every “valley.”” In passing through such a cloud, a ship is carried up and down like a roller coaster.

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Tene a TE ee le eS EE DES TT a A a a a Se i Be 60 A few years ago, two air mail pilots, flying through a storm over the mountains of western Pennsylvania, encountered the largest vertical air current so far meas- ured. Both the westbound and the east- bound planes were thrown straight up for more than 1,500 feet. One of the flyers reported that he pointed the nose of his plane down and, with the air speed indi- cator showing 140 miles an hour, hovered without descending a foot. When he emerged at last from the rising column, it was to plunge into a down-current almost as violent. HERE are four kinds of clouds—cir- rus, high, featherlike, and usually in belts across the sky between 25,000 and 30,000 feet from the ground; nimbus, thick, formless, bginging rain, usually between 5,000 and 8,000 feet in the air; cumulus, mountainlike masses drifting below 5,000 feet; and stratus, low, hori- zontal sheets of lifted fog. By studying the forms and actions of clouds, a flyer can learn much about the weather ahead. For instance, soft, deli- cate clouds indicate fine weather and light breezes. Heavy, “‘oily” clouds mean wind. Genérally speaking, the softer the clouds look, the less wind there will be; the more “greasy,” hard, and ragged they are, the stronger the wind. Another rule for everyday use is: the higher the clouds the finer the weather. When high clouds cross the sky in a direction different from that of the ground wind and the lower clouds, it means a coming change of the surface winds to conform to the movement of the upper clouds. After clear weather, light streaks and patches of white clouds in the distance indicate a probable change of conditions. They gradually increase, fol- lowed by an overcast, murky sky that grows into cloudiness. Light, misty clouds forming or hanging around moun- tain tops should be watched closely. If they rise and dissipate, the weather will be clear. If they remain stationary, wind and rain are probable. AST August, I ferried a Stearman plane east from Wichita, Kansas. Three times in one afternoon I had to side-step thunderstorms; which, by the way, are most frequent on -hot summer afternoons. I could see the approaching thunderheads far across the prairie. I would watch the direction of their ge ae , Sunset above the clouds—an unusual photograph taken from an airplane flying over a billowy sea which blanketed the earth. POPULAR SCIENCE MONTHLY CUMULUS— et 5,000FT “* ; we fra © OF PLANE OR GLIDER THROUGH CUMULUS CLOUD UP CURRENT OF AIR UNDER HILLS— DOWN UNDER “VALLEYS” “SMOG SMOKE- LADEN FOG OVER CITIE Suntan STRATUS 1,000 FT. HORIZONTAL | SHEETS OF” FOG progress, swing off my course to pass around them, and then cut back on my course behind the storm. One peculiarity of a thunderhead is that it is four or five times as long as it is wide. It advances like an airplane wing, long side foremost. The path of a thunderstorm is rarely more than forty or fifty miles across. Incidentally, in flying through bad weather, the best rule I know for deciding whether to continue or to land is to look back occasionally. You know the sort of conditions you have flown through, and if the sky ahead looks no worse than the sky behind, it is a pretty good sign you will be able to get through. It rarely takes more than half an hour to fly through a thunderstorm, but those thirty minutes seem like hours. In pitch darkness, except for fear- ful streaks of lightning which sometimes hiss past the wings, the ship ca- reens on boiling air. After one such experience, a pilot either side-steps a storm or lands before it strikes. The danger of being struck by lightning -is too great, and the violent vertical currents menace the life of a plane. These up and down cur- Marcu, 1939 A large transport monoplane flying through the clouds. The drawing at the left shows various kinds of clouds and their average heights above the earth; also how rising and descending air currents within a cumulus cloud carry a plane or glider up and down like a roller coaster. rents, on a smaller scale, make the “bumps” and “holes” in the air. “Air pockets” and “holes in the air” are merely down currents. A ship strikes one and drops until the pilot levels off. Sometimes one wing dips suddenly. It has hit a down draft. Bumps are most frequent in the air up to five thousand feet, but they are found as high as fifteen thousand feet. ARLY in the morning, bumps are close to the ground. By noon they rise to 2,000 or 3,000 feet. The four or five hours from ten in the morning to two or three in the afternoon are the bumpiest. In the morning, evening, and at night the air is smoothest. When fog begins to lift, the air is very bumpy until it all disappears. The same is true when dew or frost is evaporated by the sun. When patches of sunshine and shade are encountered on a hot day they mean a bumpy condition in the air. Unless a pilot has his safety. belt buckled, a bad bump may throw him against the stick, causing the ship to dive. I remember once flying with a student who forgot to slip the metal tongue of his safety belt catch under his belt loop. The tube of the Gosport hel- met, through which the instructor speaks from the front cockpit, caught under the catch and flipped the belt loose. At 2,000 feet, we hit a terrific bump. The pupil sprawled to the froftt of his cockpit, knocking (Continued on page 148) EXT month — “Twenty Years of Planes and Pilots.” From his recollections and per- sonal experiences as war bird, barnstormer, mail pilot, and flying instructor, Assen Jordan- off tells a picturesque story of aviation since its early days. Marcu, | PO An an a loft; ; ie cré single engag manet men, precat woun on thi At two climb Smok troop sunlig fields. throu pierci carrie Th 13,29 mane Italic My B' ish, « Ame Now the | New

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> 1939 il t re or Sezer ww t¢sf& fe Marcu, 1930 ‘POPULAR SCIENCE MONTHLY 61 POPULAR SCIENCE SCRAPBOOK News, pictures, and brief bits about unusual people, places, and things are gathered here from all parts of the world An antlike file of Italian mountain troops crossing a lofty snow field during their mountain climb. Italian Troops Scale the Alps Single File OILING along the snow-covered crags of the upper Alps, in antlike single file, hardy Italian troopers recently engaged in a spectacular mountain-scaling maneuver. Nearly a mile of marching men, tied together with long ropes as a precaution against falling over cliffs, wound up the slopes of the Bernina peak on the border of Italy and Switzerland. At its summit, Bernina is more than two miles above the sea. Much of the long climb had to be made above the clouds. Smoked glasses protected the eyes of the troopers from the dazzling glare of the sunlight reflected from the lofty snow fields. At times, the men had to struggle through local storms and against the piercing winds of the mountainside. They carried alpenstocks to aid them. The dangerous feat of scaling the 13,295-foot mountain is part of an annual maneuver by the northern troops of the Italian army to test endurance. Mystery in New Blue Gem EAUTIFUL deep-blue gems of zircon, hitherto known only in brown, green- ish, or yellow colors, recently appeared in American markets and puzzled jewelers. Now the mystery may be explained with the observation of Dr. George F. Kunz, New York jewel expert, that they may Scaling Bernina’s pinnacle, 13,295 feet high. The hardy soldiers were tied together with a series of long ropes. owe their color to the little known and only lately-discovered element hafnium. This expert, first to recognize the stone as a new variety of the semiprecious ma- terial zircon and to name it “starlite,” first set about tracking its source. All samples turned out to originate from a single place, near Chantaboon, Siam. Brown zircon crystals, he found, were heated with cyanide of potassium, a poi- sonous compound, in a crucible for several hours. When they came out some of them were of the peculiar shade of blue. These were the heavier varieties of zircon. These very varieties, Dr. Kunz points out, are those that are known to contain the element hafnium in small quantities. He suspects therefore that the hafnium produces the color, which is brought out with the aid of the chemical treatment. Despite this handling, the gems are not considered artificial by jewelers; they are prized varieties of zircon. A five-carat stone of the new blue color, it is reported, sells for about $60. The element hafnium, known only since 1923, was discovered by two Danish chemists and soon after was isolated in pure form from rare earths. Now it is known to be abundant enough to make up 1/200,000 part of the earth’s crust, though commercial uses still await it. Tells Why Mayan Prayers Brought the Rain HEN the ancient Mayas of Central America prayed for rain they got a quick reply. Their prayer was answered the same day it was offered, or very shortly after. This was not divine intervention, but a scien- tific coincidence of the seasons, according to Zelia Nuttall, fa- mous expert on Central Amer ican history who recently ad- dressed the Royal Anthropolog- ical Institute in London. The Mayans conducted their annual ceremony of sun worship and prayer for rain on the first of two days in the year when the sun, in tropical parts of the earth, stands precisely overhead. These days correspond to the astronomer’s equinoxes, well known harbingers of rain. The explanation of the downpour which followed the yearly prayer is purely physical, Nuttall de- clares. When the sun is directly overhead the ground is highly warmed. This heats the air next to the ground and causes warm, moist air to rise. In the upper air this moisture condenses to rain. The Mayans were versed in astronomy to a remarkable degree (P. S. M., Jan. ’30, p. 22), but they failed to connect the natural sequence of the sun’s position with their fervid prayers. Men Win Race with Rats RTY-THREE white rats recently vied with twenty-three college stu- dents in threading a maze at the labor- atory of R. W. Husband, psychologist of the University of Illinois, who is bent on comparing the intelligence of rats with that of men. The rats were turned loose in the maze, with a food reward at the other end. The students were blindfolded and traced the epee mea ee ee a cee viper gerne al ot ere ale: ert cnt yma eee

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SARE ERR Baas Tana Perr, 62 same maze pattern with their fingers. It was found that the students, though receiving no dinner as their reward, were quicker than the rats in winding their way through the maze. The rats erred most often in taking left turns persistently because one left turn happened to prove correct. The students, who were familiar with the idea that mazes turn right and left confusingly, tended to make the mis- take of turning alternately to right and left too regularly. ef Water Tanks Nest at Top of Eighty-Foot Tower AKING industrial buildings attrac- tive has of recent years been one of the minor accomplishments of the engi- neering world; but nowhere, perhaps, have the results been so striking as in a unique building erected in Suffolk, Eng- land. At the top of this eighty-foot ferro- concrete tower, four huge circular tanks project from the corners like the bastions of some queer medieval castle. The unique building is to be used for the manufacture of artificial silk. Above three floors of offices is a water-softening plant, where the water used in the manu- facturing processes is first treated. It is then passed to the circular tanks for storage and distribution to all parts of the works. Autumn Leaves Still Gay After Millions of Years ALEOBOTANY, the science of flower fossils, has lately brought to light some unusual specimens, autumn leaves mil- lions of years old imprinted on rock with the original colors retained. Dr. Ralph W. Chaney, paleobotanist of the Carnegie Institution in Washington, reports the find- ing of these curiosities in newly discovered fossil leaf beds of Wheeler County, cen- tral Oregon. He predicts the fossil flora found in this region will throw important light on numerous extinct plant species which must have formed a semitropical jungle in primeval Oregon. How the autumn leaf fossils preserved their color is still a mystery, but it has been explained tentatively by the pres- ence of minerals in the rock bed. POPULAR SCIENCE MONTHLY Old Wooden Water Mains Unearthed in London HE evolution of the underground pip- ing system of a large city could be partly traced in the Bloomsbury district of London, England, when replacement work was undertaken, following a series of gas main explosions, and a number of old wooden pipes used in bygone days for the transmission of the city’s water and gas supplies was unearthed. The increase in the city’s water consumption was clearly demonstrated by the difference in bore between these old wooden pipes and the steel mains installed in their place. Moreover, the decrease in the thickness of the material in proportion to the bore of the pipe, through the progressive stages of wood, iron, and steel conveyors, bears elo- quent testimony to the ever-growing effi- ciency of engineering. Above are shown sections of the old wooden mains. American Bald Eagle Is Near Extinction N A few years the American bald eagle will be seen only on coins and the coat of arms of the United States unless drastic action is taken to save these birds from extinction, according to W. Dewitt Miller, ornithologist of the American Mu- seum of Natural History, New York City. In the last twelve years, about 70,000 bald eagles are said to have been slaugh- tered in Alaska alone. When an emblem for the nation was being selected, Benjamin Franklin de- clared ‘‘the eagle is a bird of bad moral character.” Most people agreed. Eagles were accused of stealing lambs and even of carrying away children. Recent studies made by Dr. Francis H. Herrick, of Western Reserve University, Ohio, have proved the bald-headed eagle guiltless of most of the crimes attributed to it. The Old Traffic Problem EARLY 300 years before the auto- mobile appeared, traffic congestion was already a problem. In London, a retired naval officer, named Bailey, had bought carriages previously used only by Marcu, 1930 aristocrats, dressed the drivers in livery, and had begun carrying passengers. By 1635, fifteen years after the Pilgrims settled in America, London was already discussing the traffic problem. A procla- mation resulted, barring semi-public ve- hicles from the streets. Within the memory of people still living in England, there were only 2,000 public carriages in the largest city in the world. In the last few decades the coming of the taxicab and the omnibus has increased traffic many fold. Twenty-five million automobiles now run on the roads and streets in America alone. Widening thor- oughfares and restricting parking are temporary steps in traffic control. Builds Novel Telescope in His Back Yard UR hundred individual lenses mounted on a wooden rack are being designed to provide a reflecting surface of 100 square feet in an unusual experiment in telescope construction by C. W. Wood: worth, professor of entomology at the University of California. If it is com- pleted and proves successful, it will be the largest reflector telescope in the world. At present the largest is the 100-inch reflector of Mount Wilson Observatory in California, made of one solid piece of glass. With the aid of his novel instrument, Professor Woodworth expects to see and photograph the largest image ever made of a heavenly area. He has worked for two years on this telescope, grinding each of the 400 lenses with a special apparatus and fitting them together. The instrument is being built in the professor’s own back yard. On top of his barn, sixty feet away from the reflecting mirror, he has erected a scaffolding on which he will mount an_ eyepiece. Through this he will make his observa- tions, picking up the image reflected by the united lenses. Professor Woodworth shows how the eyepiece of his telescope will be mounted above his barn. MaRCcH, 193 ry Feeding the field sparrov wittingly ha cowbird, dt the role of | Cowbirds af build their © stead, they their eggs 11 other and Below: T having grac at the right The goldfin “wild cane color and

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MaRCH, 1930 Feeding the foundling. A field sparrow, having un- wittingly hatched a baby cowbird, dutifully plays the role of foster mother. Cowbirds are too lazy to build their own nests. In- stead, they slyly deposit their eggs in the nests of other and smaller birds. Below: The five goldfinches, having graduated from the nest at the right, are learning to fly. The goldfinch often is called the wild canary’’ because of its color and its canarylike song. POPULAR SCIENCE MONTHLY 63 How the Mother Birds heed Their Young “Me next!” While one baby chipping sparrow gets a mouthful, the other clamors for its turn. So intent was the mother that she paid no attention to the photographer less than six feet away. These friendly birds, smallest of the sparrow tribe, line their nests with horsehair, Left: “Close harmony” from the goldfinch quintet. When the mother arrived with food five heads popped up as far as necks would stretch. A long thread attached to the camera shutter made possible this remarkable close-up picture. Instead of carrying food in its bill, the par- ent flicker partially swallows it and pumps it down the throat of the young. “Golden-wing- ed woodpecker” is one of its forty names. Left: Treating ‘em rough. The mother chipping sperrow uses one baby as a perch while she feeds the next in line. It was poor footing, and a second after the camera clicked, all three birds fell off. os ogee ~ if | it i if ia ' i lL ' I i} i

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=a atesend. aD Rt IE TR 64 POPULAR SCIENCE MONTHLY A pelican and a cormorant serve this fisherman in place of hook, line, and sinker. When the birds return from fishing expeditions, he makes them disgorge their catch. sae = Re a “ - ; ‘ Since fish of the smelt family refuse to strike at a baited hook that is not in mo- tion, German smelt fishermen call thc wind to their aid, rigging windmills which spin the bait as they revolve. Marca, 1939 More Ways Than One to Catch a Fish Some Anglers Prefer Arrows, Spears, or Traps; Others Make the Birds Do the Work—Unusual Picture Stories of a Favorite Sport the World Over With a “ bottomless bird cage’”’ type of fish trap, this Filipino woman pokes around in shallow water until she can thrust it down over a fish. Then she reaches through the hole in the The blimp at the left served three Los top and grabs the Mae Angeles flying anglers as a fishing craft. Ninety miles out they dropped their lines into the Pacific and landed 150 pounds of fish in a morning. At the height of the great yearly salmon run on the Columbia River in Oregon, these Indians at Celilo Falls line the bank with long hooked spears. They spear enough fish for a year’s supply. Mal r-osseceuom ¢

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, 1939 le bird rap, llow ish. cL Marcu, 1930 Here’s a real idea for casting the line far out beyond the shallows. Working from the wind- ward shore, these fishermen fill toy balloons with carbon dioxide gas which they have carried on their motorcycle. To the balloons they attach their lines with baited hooks and sinkers. The wind sweeps the balloons out, line and all. One of the great fish traps which may be seen along the upper Pasig River on the island of Luzon in the Philippines. The fish are caught in large dip nets suspended from a supporting structure of long bam- boo poles. The fisherman, standing on a small dock projecting from shore, lowers and raises the heavy nets by means of ropes aided by counterweights. POPULAR SCIENCE MONTHLY “Watch Dad land a big one!’’ This unusual photograph shows how a Javanese father and son go fishing. Instead of hook and line, they use a bow and a long, three- pointed arrow. Wading out to a reef projecting from the water, they watch for a fish to come within range—and the arrow speeds to its mark. This sort of fishing is real sport, for it requires keen eyes and skillful marksmanship. Many South Sea Islanders prefer the throw-net for fishing. In the picture at the right, two Chamerros, natives of Guam, in the Mariana Islands, demon- strate their method of casting. Carrying small nets, folded and weighted, they wade out from shore. When one spots a school of fish, he quickly casts his net, outspread, somewhat as a cowboy throws a lasso. In this sport the natives develop surprising skill.

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Puzzle: lines would meet, if extended, the creature will be discovered. URKING on the sea bed of the Great Barrier Reef, off Queensland, Aus- tralia, and so shaped and colored as to be almost indistinguishable from its sur- roundings of horseshoe clams, knobby corals, and algae-covered stones, a fine specimen of the ‘‘stonefish,” called the world’s most repulsive fish, was discov- ered recently by G. P. Whitley and W. Boardman, two scientists of the Aus- tralian Museum. With its heavy, jagged fins, the fish resembles a rough-hewn, winged cornu- copia. Instead of scuttling away at the scientists’ approach, the creature re- mained absolutely motionless, while they took the photograph reproduced above. Then they prodded it with a stick, and it instantly raised three poisonous spines along its back. Its skull-like head was distorted into a series of bumps and hol- lows of a.lemon-yellow color, and pock- marked with gray. The spines, too, were yellowish, with their covering puckered into fronds and frills that completely dis- guised their poison bags and needle points. Carefully the men netted the strange fish and carried it home at arm’s length. In captivity it died. The stonefish relies upon its spines, armed with their deadly poison, to pro- tect it from all enemies, which explains why this specimen did not dart away at the scientists’ appearance. Occasionally the poison has a fatal effect upon its vic- tims. But one victim—a fisherman who had a finger scratched by one of these spines—recovered after much pain. For fifteen hours after the scratch, he told the scientists, he suffered intense agony and could get no relief from either doctors or herbalists. At times it felt as though someone were twisting each of his verte- brae separately. Germs in Wound I11 Years GERM colony which took up lodging in the shoulder of a British Tommy when he was wounded in battle eleven years ago was recently found to be still alive, according to the report of the oper- POPULAR SCIENCE MONTHLY “The Most Repulsive Fish in the World” The hideous face of the stonefish captured from the hiding place shown in upper photo. ation which brought it to light, made by Dr. R. J. V. Pulvertaft of St. Thomas’ Hospital, London. That a colony of bacteria, organisms only a few hundred-millionths of a centi- meter in diameter, should demonstrate the power to hold out to such a hearty old age is a remarkable fact of biology. The germs had to battle against not only the resistance of the soldier’s body, but also a serum which was injected at the time of his first operation at the front in 1918. Some months ago the soldier com- plained of pain in the shoulder. Surgeon Pulvertaft operated and discovered a shell fragment which had been missed before, surrounded by the hardy mi- crobes which had regained their vitality and started to make trouble again. Ice Crystals Ages Old N CAVES in southwestern France water crystals have been found which are estimated to date back to prehistoric times. They were discovered in the “‘Cave of the Sister of the Falls” by archeologists who were exploring for traces of primitive men, and proved to be perfect water crystals, probably the largest ever found. Some were about four inches across and an inch thick. Solid natural iceor artificial ice seldom con- tains perfect crystals. To find them one Marcu, 1930 must examine snowflakes or else the ‘*frost pictures” which appear on window panes in extremely cold weather. The formation of the unusual ice crystals in the French cave has been attributed to the remarkably constant conditions of moisture and freezing temperature which prevail in the cave. If a chemist were to make similar crystals of salt or sugar in his laboratory he would have to have similar constant conditions. But in the case of the water crystals Nature did the work in her own laboratory without a flaw long before man’s laboratories were even con- ceived. Twenty-Foot Water Wheel 57,000-horsepower water wheel, said to be the biggest ever built in the United States, is nearing completion at a Newport News, Va., shipbuilding yard. It is America’s bid to capture supremacy in the building of the great rotors, of which the world’s largest are those of 70,000 horsepower at Niagara. Hitherto large water wheels usually have been imported from Europe. When completed, the new wheel, twen- ty feet in diameter and weighing 150 tons, will be installed in a 100,000-horsepower hydroelectric plant at Spiers Falls, N. Y. Aluminum Playing Cards LAYING cards made of aluminum, with colored faces and backs, are the newest thing for a game of bridge. They look and feel like ordinary cards, except that they are a little heavier. On the beach or porch, the cards will not blow away, and they are handy for the camper, too. If soiled or sticky, they can easily be washed. Giant Mushroom as Large as a Hatbox HE historic woods of Fontainebleau, France, have gained added fame from their ability to produce giant specimens of fungus. In the recent exposition of mushrooms and like growths in the Muséum d’Histoire Naturelle, Paris, France, appeared one such specimen, illustrated in the photograph. Some idea of the huge size of this growth may be gained by comparing it with the human hand resting upon the top of the dead wood to which the fungus is attached. ait aid | This huge mushroom, picked at Fontainebleau, would make a meal. Compare it with the hand. MaRCH —— more phan of In close. coye: thea are | rope sos,”’ The: seasc One as m phot show exert strer esca in t abov in th stru; stan

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Marcu, 1930 POPULAR SCIENCE MONTHLY , 67 Roping Wild Elephants in the Jungles of India A futile fight against the rope that holds him. , These wild Asiatic elephants become dangerous only when disturbed or attacked. Then they charge and seek to trample their foes to death. ORE exciting than a Wild West rodeo, and more perilous, is a wild ele- phant hunt in the hill forests of India, as pictured here in close-range photographs. De- coyed by tame efephants, the angry, trumpeting beasts are rounded up in herds, roped with enormous “‘las- sos,”” and captured alive. The stout ropes are made of seasoned jute by natives. One of these tethers weighs as much as,500 pounds. The photo in the oval above shows a captured elephant exerting the last bit of its strength in a vain effort to escape. The young tusker in the picture immediately above has become entangled in the heavy rope during the struggle. A full grown male stands about ten feet high. Meet “us ay to — * Rounding up a herd of wild elephants—the climax of the hunt. The animals travel in “family parties’’ numbering from ten to fifty, or occa- sionally even 100 individuals. Each herd is led by a female. Subdued and roped together, these wild elephants are en- joying their first bath in captivity. The Indian ele- phants require plenty of shade and water, and no animals enjoy a bath more thoroughly. They are good swimmers and, by means of their trunks, can breathe when their entire bodies are beneath the surface.

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66 Puzzle: lines would meet, if extended, the creature will be discovered. URKING on the sea bed of the Great Barrier Reef, off Queensland, Aus- tralia, and so shaped and colored as to be almost indistinguishable from its sur- roundings of horseshoe clams, knobby corals, and algae-covered stones, a fine specimen of the ‘‘stonefish,” called the world’s most repulsive fish, was discov- ered recently by G. P. Whitley and W. Boardman, two scientists of the Aus- tralian Museum. With its heavy, jagged fins, the fish resembles a rough-hewn, winged cornu- copia. Instead of scuttling away at the scientists’ approach, the creature re- mained absolutely motionless, while they took the photograph reproduced above. Then they prodded it with a stick, and it instantly raised three poisonous spines along its back. Its skull-like head was distorted into a series of bumps and hol- lows of a.lemon-yellow color, and pock- marked with gray. The spines, too, were yellowish, with their covering puckered into fronds and frills that completely dis- guised their poison bags and needle points. Carefully the men netted the strange fish and carried it home at arm’s length. In captivity it died. The stonefish relies upon its spines, armed with their deadly poison, to pro- tect it from all enemies, which explains why this specimen did not dart away at the scientists’ appearance. Occasionally the poison has a fatal effect upon its vic- tims. But one victim—a fisherman who had a finger scratched by one of these spines—recovered after much pain. For fifteen hours after the scratch, he told the scientists, he suffered intense agony and could get no relief from either doctors or herbalists. At times it felt as though someone were twisting each of his verte- brae separately. Germs in Wound I11 Years GERM colony which took up lodging in the shoulder of a British Tommy when he was wounded in battle eleven years ago was recently found to be still alive, according to the report of the oper- POPULAR SCIENCE MONTHLY “The Most Repulsive Fish in the World” The hideous face of the stonefish captured from the hiding place shown in upper photo. ation which brought it to light, made by Dr. R. J. V. Pulvertaft of St. Thomas’ Hospital, London. That a colony of bacteria, organisms only a few hundred-millionths of a centi- meter in diameter, should demonstrate the power to hold out to such a hearty old age is a remarkable fact of biology. The germs had to battle against not only the resistance of the soldier’s body, but also a serum which was injected at the time of his first operation at the front in 1918. Some months ago the soldier com- plained of pain in the shoulder. Surgeon Pulvertaft operated and discovered a shell fragment which had been missed before, surrounded by the hardy mi- crobes which had regained their vitality and started to make trouble again. Ice Crystals Ages Old N CAVES in southwestern France water crystals have been found which are estimated to date back to prehistoric times. They were discovered in the “‘Cave of the Sister of the Falls” by archeologists who were exploring for traces of primitive men, and proved to be perfect water crystals, probably the largest ever found. Some were about four inches across and an inch thick. Solid natural iceor artificial ice seldom con- tains perfect crystals. To find them one Marcu, 1930 must examine snowflakes or else the ‘*frost pictures” which appear on window panes in extremely cold weather. The formation of the unusual ice crystals in the French cave has been attributed to the remarkably constant conditions of moisture and freezing temperature which prevail in the cave. If a chemist were to make similar crystals of salt or sugar in his laboratory he would have to have similar constant conditions. But in the case of the water crystals Nature did the work in her own laboratory without a flaw long before man’s laboratories were even con- ceived. Twenty-Foot Water Wheel 57,000-horsepower water wheel, said to be the biggest ever built in the United States, is nearing completion at a Newport News, Va., shipbuilding yard. It is America’s bid to capture supremacy in the building of the great rotors, of which the world’s largest are those of 70,000 horsepower at Niagara. Hitherto large water wheels usually have been imported from Europe. When completed, the new wheel, twen- ty feet in diameter and weighing 150 tons, will be installed in a 100,000-horsepower T . hydroelectric plant at Spiers Falls, N. Y. Aluminum Playing Cards LAYING cards made of aluminum, with colored faces and backs, are the newest thing for a game of bridge. They look and feel like ordinary cards, except that they are a little heavier. On the beach or porch, the cards will not blow away, and they are handy for the camper, too. If soiled or sticky, they can easily be washed. Giant Mushroom as Large as a Hatbox HE historic woods of Fontainebleau, France, have gained added fame from their ability to produce giant specimens of fungus. In the recent exposition of mushrooms and like growths in the Muséum d’Histoire Naturelle, Paris, France, appeared one such specimen, illustrated in the photograph. Some idea of the huge size of this growth may be gained by comparing it with the human hand resting upon the top of the dead wood to which the fungus is attached. ’ me This huge mushroom, picked at Fontainebleau, would make a meal. Compare it with the hand. MARCH. more phant of In close- coyec the a are 1 ropec sos,”’ The : seasc One as m phot show exert strer escay in tl abov in th stru; stan

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Marcu, 1930 POPULAR SCIENCE MONTHLY ORE exciting than a Wild West rodeo, and more perilous, is a wild ele- phant hunt in the hill forests of India, as pictured here in close-range photographs. De- coyed by tame elephants, the angry, trumpeting beasts are rounded up in herds, roped with enormous “‘las- sos,” and captured alive. The stout ropes are made of seasoned jute by natives. One of these tethers weighs as much as 500 pounds. The photo in the oval above shows a captured elephant exerting the last bit of its strength in a vain effort to escape. The young tusker in the picture immediately above has become entangled in the heavy rope during the struggle. A full grown male stands about ten feet high. Roping Wild Elephants in the Jungles of India 67 A futile fight against the rope that holds him. These wild Asiatic elephants become dangerous only when disturbed or attacked. Then they charge and seek to trample their foes to death. Rounding up a herd of wild elephants—the climax of the hunt. The animals travel in “family parties’? numbering from ten to fifty, or occa- sionally even 100 individuals. Each herd is led by a female. Subdued and roped together, these wild elephants are en- joying their first bath in captivity. The Indian ele- phants require plenty of shade and water, and no animals enjoy a bath more thoroughly. They are good swimmers and, by means of their trunks, can breathe when their entire bodies are beneath the surface. 9 tempt! a or cose a pouhadyrarnes

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Ss Saat 6 NS EY SE ERE LS. a ‘ — a ke | See er New Devices for the Home To save the hands, these metal “fingers” hold steel wool, dishrags, or polishing cloths. A sliding metal plate serves as a catch to seize the cloth or wool firmly. Slit three edges of a cercal box cover, snap on this special clip, and the result is a container that closes tight to guard against spilling and to exclude dust. It is useful also on other boxes. POPULAR SCIENCE MONTHLY Salads are made more in- viting, vegetables more appetizing, by a new set of three shredders—fine, coarse, and smooth. The set nests to occupy small space in a drawer. The fine shredder is in use. The iron cord is kept out of the way by a new reel, at the left, that clamps to the ironing board. The cord is drawn out easily, and firm gentle tension reels it back into the holder. The reel swivels, turning either way so as to follow the direction of the iron. Tray and serving table combined. Carried into the room, the tray’s legs drop at the touch of a button. Marca, 1939 Built as a table, this electric heater warms a chilly room. Warm air, circulated by a fan be- neath the table top, is shot out sideways in every direction through a nar- gow crack encircling the table just beneath the top. Switches provide much or little heat as desired. This handy guide device helps to cut a tomato into neat slices of even thickness. Curved prongs guide the knife and keep it from slip- ping. There are no spoiled slices to be wasted. oma Mar

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Marcu, 1930 POPULAR SCIENCE MONTHLY 69 ~-s ‘ wt band yor Sy . Ri Sasa Se i | i] Re , || An auxiliary electric heater for extremely cold weather is con- tained in a cabinet which slips right over the steam radiator. 18 FO peg geial i af eels ity ge semree ae : 3 i 8j ee oy Bene cae SES Sass -2 he s,m #a a. » 2 Re és es Le} Se & ge *i8 722 Sep itie e@e Ber 8k eee ge Fhe - Fay oe ee ee | ~ & hag 2 Bing ane Sat ge; 28% A rain-soaked overcoat or an evening’s wash may be dried with equal ease in this new home electric dryer. A fan at the top forces air downward over a red-hot coil, creating a warm blast. Hot water is safely poured from this novel kettle. Simply squeezing the two handles together tilts the pot, locks the lid, and allows the water to escape from the lip. The tight lid keeps steam from the hands. When the coffee is done, a new electric drip percolator shuts itself off. It is made in two parts, with the heating element in the base. Per- colating starts when the top is set on the base as shown in the upper picture. Above is a view of the base, the finger pointing to the contact which starts the percolating when the top is A comfortable armchair by day (above) is transformed by one simple motion into this placed upon it. One advantage is that the top, single bed for the unexpected overnight guest. Deep coil springs support the mattress when removed, can be washed without dan- which fits inside the chair when closed. The inventor declares the bed will not tip over. ger of short-circuiting an electric connection.

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70 POPULAR SCIENCE MONTHLY Travis Hoxe, Editor Raymonp J. Brown, Managing Editor Artiur WaKELING, Home Workshop Editor Aurrep P. Lane, Technical Editor Epcar C. WHEELER, Associate Editor IsrAEL Dosxow, Art Editor E. E. Free, Contributing Editor Published Monthly by Popular Science Publishing Company, Inc., 381 Fourth Avenue, New York City. Single Copies Twenty- five Cents. In the United States and Its Possessions and in Canada, $2.50 the Year. In All Other Countries, $3.00 the Year. Is Aviation Falling Behind? ECENTLY the Daniel Guggenheim Safe Aircraft Con- test came to a close. Any hope of its being a “contest” in any accepted sense of the word faded long before the end. An airplane automatically received the $100,000 award because it was the only one successfully to complete the eighteen required tests for safeness. These requirements were admittedly difficult, and all credit is due the winner for its ability to satisfy them. Yet the dis- turbing fact remains that there were no finals in the competi- tion, simply because no other airplane entered could do it. The record of the competition is disheartening; twenty-seven entries promised; fifteen actually entered; nine remaining after withdrawals; three remaining after the preliminary tests, and only one that could pass them all. Two of the “safe” airplanes » crashed. This is an alarming record. It confirms what keen observers have been declaring—that in response to the enthusiasm de- veloped by Lindbergh’s Paris flight, manufacturers have been turning out airplanes in quantity along conventional lines, rather than pausing to experiment extensively with radical designs that might lead to greater safety. This opinion is shared by at least one airplane manufacturer, who now plans an extensive research program to develop new aircraft types. His action is well taken. It is high time that makers of aircraft discard the plan of letting well enough alone and catch up with the pioneering research spirit now demonstrated by other great American industries. Good Memory—Easy as epi? jk recently reported memory aid of Sir James H. Jeans, British astronomer, for recalling a precise value of “pi”— the ratio of a circle’s circumference to its diameter—calls to mind more than one method of jogging up a wayward mind. Sir James is the author, it may be explained, of the edifying sentence, “How I want a drink, alcoholic of course, after the heavy chapters involving quantum mechanics!” The number of letters in each word of this sentence helps his students, be says—and possibly Sir James himself, who knows?—to recall the value of pi to the fourteenth decimal place, which is 3.14159265358979. Absent-minded pedants, and students too, profit by similar tricks. The chernical formula of borax, Na2B,O,, is still re- membered by a former chemist, who has long since abandoned that pursuit for other fields, because his old-time professor Marcu, 1930 pointed out that the “N-A-two” came “B-fore” the “OQ. seven.” It has a lyrical ring to it. And there was the ingenious college student who memorized his chemistry laboratory procedure by putting it into rhyme, Of his verse only this fragment remains: “To obtain a precipitate, testing for lead, The solution is neutral at best; For if acid dichromate is present, instead, You will get a less delicate test.” Thus the “Thirty days hath September” kind of memory- jogger has its place in science, too. And, after all, why not? Next—Built-In Radio T IS rumored that various forms of so-called automatic tuning will be featured in next year’s radio receivers. This seems logical, considering that there isn’t much room left for improvements in tone quality, volume, sensitiveness, and the other qualities most desired in a set. Indeed, the radio receiver may eventually be classed with other mechanical apparatus around the house that now perform their valuable functions sight unseen. The old-fashioned parlor stove has been banished by the far more efficient cellar heating plant. The craze for open-work plumbing is giving way to the demand for built-in bathtubs. Even the radiators must hide their homely features under fancy grill work screens. Perhaps the radio of the future will become a simple enam- eled box to be installed, like other household machinery, in the cellar, attic, or an out-of-the-way closet. The dynamic speaker, or some possible successor, may become a regular part of the living room wall construction. A Great Air Sport * MILLION glider pilots by 1935.” That is the aim of the National Glider Association, recently expressed by its honorary president and founder, Edward S. Evans. Gliders cradled the earliest airmen. They produced the airplane. Now they are offering sky-minded 1930 Americans an opportunity to get into the air, enjoy the thrill of birdlike flight, and grasp the rudiments of plane piloting with a minimum of risk and expense. Two hundred thousand enthusiasts have joined soaring clubs in Germany. We predict that a far greater number will be flying engineless planes in this country within the next few years. The radio, the small motor boat, the automobile, began with a handful of devotees, and the number of their users has grown to millions. The thousand members of the thirty-two gliding clubs affiliated with the National Glider Association are pioneers in a sport which will soon be familiar in all parts of the country. POPULAR SCIENCE MONTHLY, through a series of articles commencing in this issue, hopes to stimulate greater interest in this most attractive of air sports. They Are Saying— “LTALF of the total work of the world is done in the United States.”—Dr. Thomas T. Read, Professor of Mining, Columbia University. “Speech in the theater has felt the influence of the telegraph, the telephone, and the typewriter. The influence of all our time-saving, distance-killing devices is evident in most of the speech, staccato and brief, that I overhear today.”—Professor George Pierce Baker, head of Yale University Dramatic Department. “The most valuable stone in the world today is the emerald of pure water.” —Dr. George F. Kunz, New York gem expert. “There is no such thing as a pure race anywhere. Even in Scandinavia, supposed home of the Nordics, not fifty percent of the people can be classed as Nordics.”—Dr. Fay-Cooper Cole, Professor of Anthropology, University of Chicago. “The time is not far distant when meats will be cut up into steaks, chops, roasts, and the like at the central meat-packing plants, then frozen, packaged, and distributed through grocery chains, independent grocers, and other outlets in the same handy way that groceries now are sold.” —Charles C. Small, President, American Ice Company. “The year has been gratifyingly and unexpectedly rich in progress.”—Dr. Charles G. Abbot, Secretary, Smithsonian Institution. MakRcE ceive in oO large gree pler tube: tube A pe amp appl age the feat solu volu vary grid troll tive brog in a mar toge blat the our rest trot sub twe scrt at ser tak clo tul an wi br gri bi ret co

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Marcu, 1930 How to Control | Screen Grid Experiments on the POPULAR SCIENCE MONTHLY Distance Getter show ways to get rid of cross modulation and improve selectivity of the receiver By ALFRED P. LANE NGINEERS hailed the appearance of A. C. type screen grid tubes with enthusiasm. The new tubes, they said, would make radio re- ceivers easier to design and more efficient in operation. Their predictions have largely been fulfilled. For any given de- gree of sensitiveness it is easier and sim- pler to employ a circuit using screen grid tubes. In one respect, however, the screen grid tube has brought a distinctly new trouble. A peculiarity of the new tube is that its amplification depends on the voltage applied to the screen grid. As the volt- age is reduced, so is the effectiveness of the tube. Engineers believed that this feature would prove to be the long sought solution of the problem of controlling the volume of a full electric set. Consequently varying the voltage applied to the screen grid now is the popular method of con- trolling volume on a screen grid set. Unfortunately, however, when a sensi- tive screen grid set is used near several broadcasting stations this method results in apparent lack of selectivity. Stations many degrees apart on the dial jumble together, and the set owner naturally blames the new screen grid tubes. Experiments by the engineering staff of the Popular Science Institute, working on our Screen Grid Distance Getter, have resulted in locating the cause of the trouble and in working out a remedy. When a sensitive screen grid receiver is subjected to powerful local signals from two or more stations, the volume control must be turned down so far that the screen grid of the tube actually operates at a very low potential, resulting in serious reduction in the control grid bias. Under such conditions cross modulation takes place. HE common method of designing a radio circuit is to use an antenna coil closely coupled to the grid coil of the first tube. The antenna circuit is left untuned and, in consequence, it is literally alive with the carrier waves of many different broadcasting stations. When the screen grid voltage is reduced too low there is a grid current flow owing to the lower C bias, and the effect is to give the tube a rectifying action. Each carrier wave, of course, carries its own voice modulation POPULAR SCIENCE MONTHLY that represents the broadcasting at that particu- lar station, and the rectifying ac- tion produces the cross modulation. This means that the modulation of one carrier wave is impressed on the other. The re- sult is that no matter how many tuned stages are used, the two powerful stations cannot thereafter be separated because each carries a definite impression of the modulation of the other wave. There is a definite way by which the radio set owner can distinguish between cross modulation and ordinary lack of selectivity. Ii cross modulation is taking place, both the station that is tuned in and the interfering station will become weaker as the dial is moved away from the tuned-in station’s wave length; and per- haps both will disappear altogether before the pointer reaches thé division on the scale at which the interfering station normally is heard. If the trouble were true lack of selectivity the interfering station would sound louder as the station to which the dial was tuned faded away. The solution of the problem, as worked out in the Popular Science Institute radio laboratory, is to abandon the present method of controlling the screen grid tube and substitute the following method. Instead of applying a varying voltage to the screen grid, this element of the tube is maintained continuously at the rated working voltage which, in the case of the UY-224, is ninety volts. Then the volume is controlled by changing the bias applied — 90Ve Wiring diagram of improved screen grid vol- ume control, which prevents cross modulation. Experimenting with the Screen Grid Distance Getter in the radio laboratory of the Popular Science Institute to improve selectivity. to the control grid of the tube. The cir- cuit, shown in the diagram, should allow the control grid bias to be increased from minus three volts, the rated working voltage of the latest UY-224 tube, up to ten or even twenty volts, depending on value of resistance Z. This method eliminates the possibility of grid current flow and makes cross modulation impos- sible. For the set owner the apparent result is to improve the selectivity. There is a possible disadvantage of any type of volume control that works by changing the plate current of the tubes. If used on an extremely sensitive set in a locality close to a number of broadcasting stations, and if the set is connected to a long outdoor antenna, there may be signs of distortion on the most powerful local stations when the volume is turned way down. The remedy is to use two antennas —a short one. for local reception and a long one for distant stations a few de- grees on the dial from the local station. Builders of the Screen Grid Distance Getter described in the September, 1929, number of PopuLAR SCIENCE MONTHLY, and now available in Blueprint 109, will find this diagram particularly useful in re- vising the circuit to conform to the new method. Of the second two tubes shown in the present diagram the first is arranged in exactly the same way as before, con- nections being made to the two wires indicated by arrows. Resistances R2, R5, R3, and R6 are of the same values as in the original circuit. R7 also is the same 10,000-ohm potentiometer. Z should be a good fixed resistance of any value from 50,000 to 100,000 ohms. Of course, only the wires involved in the new method of control are shown in this diagram. All other wires remain as in Blueprint 109. By this new method of control a con- stant but small flow of current going through resistance Z produces a drop in potential as it flows through the portion of R7 that is included in the circuit, and by moving the contact of R7, the bias of the control grid G can be set at any value from minus two and a half to three volts to minus six or seven volts.

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POPULAR SCIENCE MONTHLY Marcu, 1930 Useful Hints for the Siidics Pend Rewiring for the New A. C. Tubes How to Adapt a Battery Set to Use 227 Heater Tubes; Plugging in the Headphones for Distance Reception HE simplest method of re- wiring an old battery set for A. C. operation is to use type 227 heater A. C. tubes in all sock- | ets except that of the | last audio stage, in | which a type 171A power tube should be used. In PopuLarR SCIENCE MONTHLY for February, 1929, on page 65, was outlined a method of rewiring a DETECTOR 227 former winding. The K terminal of the de- tector socket goes to the old filament wiring at the nearest point. The K terminals of the radio-frequency sock- ets are connected to 1,500-ohm resistances and the other terminal of the resistance con- nected to the old fila- ment wiring at the nearest point. This applies to the first audio socket also, 2N° ~uvio I71A 6 battery set, using 226, 227, and 171A tubes. Now that the 227 tube has been so greatly improved, however, more satisfactory re- sults will be obtained by using these tubes in place of the 226 tubes formerly used in the radio-frequency and first audio stages. The fact that the 227 tube has less inter- element capacity and a somewhat higher amplification factor insures better results with this tube in the radio-frequency stages, particularly in sets of the neutro- dyne type. Also, the 227 tube is more easily balanced than the type 226 and operates with less hum in the first audio stage. Assume that the battery. set is of the conventional five-tube type, with two tuned radio-frequency stages, a detector, and two audio stages; and that it is now operated with a storage battery and a B eliminator. The new apparatus necessary to change it over to full electric operation with type 227 tubes will consist of four Y-type sockets, three 1,500-ohm fixed resistances, two one-microfarad by-pass condensers, one 2,000-ohm fixed resist- ance, and one twenty-ohm center tapped fixed resistance. A filament heating trans- former capable of delivering two and one half volts, and with sufficient output to supply four 227 tubes, will be necessary. If your B eliminator is not fitted with a separate five-volt winding suitable for operating the filament of the type 171A tube, a small five-volt filament heating transformer will be needed. Remove the wires leading to the G and P terminals of the radio-frequency, de- tector, and first audio sockets, and cut the filament wiring loose right at the socket. Connect each pair of filament leads that supplied battery current to the old sockets together. On the last socket, which holds the 171A tube, simply remove the two filament wires and connect them together. Then refer to the accompanying diagram. Diagram showing new wiring necessary to change a battery operated set to one using type 227 A. C. heater tubes. The fixed resistance placed in the first audio stage is of 1,500 ohms. Place the Y-type sockets in position and reconnect the G and P terminals. The H or heater terminals are connected in parallel by twisted wires to twisted wires running to the two and one half volt winding of the filament heating trans- former. The last audio socket filament terminals are connected by twisted wires to the five-volt filament heating trans- - A B C’s of Radio HE selectivity of any radio re- ceiver is always poorer on the lower wave lengths. Their power and frequency separations being equal, it is easier to choose between stations when they are near the upper end of the broadcast band of wave lengths. A radio receiver is not a miracle worker. It cannot separate stations if they are on the same wave length,and a check- up of the assigned frequencies in use in this country shows that near the low end of the dial there are many points where two or more stations should be received at exactly the same point. In theory, the assignments are such that stations supposed to be working on the same wave length or frequency are located far apart. In practice, however, the great range of even the smallest station on a good night results in a hopeless hash at many points on the dial. There seems to be no way to improve the situa- tion except by eliminating many of the stations now broadcasting. = except that a one-mi- crofarad by-pass con- denser is connected around the resistance. Connect the ends of the twenty-ohm cen- ter tapped fixed resistance to the five-volt winding. The 2,000-ohm fixed resistance is connected in with one end to the old filament wiring. The “X” in the diagram represents the nearest point on the old battery filament wiring. The B eliminator iscon nected to the “minus B,” “detector” and “amplifier” binding posts as usual. If the receiver lacks sensitiveness, by- pass one or both of the 1,500-ohm resist- ances on the radio-frequency stages. A quarter or half microfarad condenser is ample. If the set is a six-tube outfit, another Y-tube socket and another 1,500-ohm resistance will be needed. For volume control use a high resist- ance, noninductive, noncapacitive poten- tiometer connected across the antenna and ground binding posts with the antenna lead connected to the contact arm. Use Headphones for ‘‘DX”’’ AR phones are superior to a loud- speaker in hunting distant stations, as even very faint signals can be heard and headphone reception late at night does not disturb sleeping neighbors. It isn’t practical, however, to connect the headphones in place of the loudspeaker without some way of decreasing the vol- ume. The simplest method of doing this is to use a high grade variable resistance connected across the output terminals in parallel with the headphone cord tips. Special output volume control units suitable for this purpose are available that will make it unnecessary to do any wiring inside the receiver. The set’s normal volume control cannot be used because turning it down reduces the radio-frequency amplification, very necessary for distance reception. MARCH, of inter chinery nated. Whe with ra fore, is teriere! Discon: receive appear: it is ca made s of the | the ele If, © tinues, by mé power sometk as a lo cates t the sol Figure of inte connec socket This a interfe way 0! Inte may b The : filter shown effect to by: tions noises Cas ferenc a mol In ack radio- must cuit a The | easy | pulsa coils, appre on t that very the © form with provi the | the r Tk man- trica! cont

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1930 Marcu, 1930 Easy Ways to Shut Out Man-Made Static By JOHN CARR LTHOUGH natural static is a radio nuisance for which no remedy has been found, man- made static, including all types of interference produced by electrical ma- chinery, can, in many cases, be elimi- nated. Whenever extraneous noises interfere with radio reception the first step, there- fore, is to determine to which type of in- terference they belong. The test is simple. Disconnect the antenna wire from the receiver, and if the interfering noise dis- appears immediately, it is safe to say that it is caused by natural static or by man- made static that is not coming in by way of the power wires that supply current to the electric set. If, on the other hand, the noise con- tinues, the trouble almost surely is caused by man-made static coming over the power wires unless, of course, there is something defective in the set itself, such as a loose connection. If a check-up indi- cates there is nothing wrong with the set the solution of the problem is as shown in Figure 1. An approved type POPULAR SCIENCE MONTHLY commutator of a motor, by a trolley sliding along an overhead wire, or wherever the flow of electric current is suddenly in- terrupted. An ele-tric spark, tests have shown, always produces trains of untuned high frequency elec- trical oscillations. In character these are essentially the same as the radio broadcast wave except, of course, that they are virtually untuned, so that they usually can be heard at any point on the dial. They flow away from the point at which the spark occurs through both sides of the wire and thus along the power wiring into the radio set. If the spark is exceptionally strong it will produce a radiation in the air from the wire. This form of man-made static in many cases is incurable, particularly if there is no way by which the spark oscil- lations can be smothered at their source. The factory built interference elimi- nators illustrated in Figure 3, or similar home assembled out- fits, may be used of interference eliminator is connected between the wall socket and the radio set. This automatically eliminates interference coming in by a either at the receiver to prevent man-made static from getting into the set by way of way of the power wiring. Interference eliminators FIG.2 may be of two different types. the wiring, or to kill the interfering oscil- lations at their source, The simpler contains only filter condensers wired as shown in Figure 2-a. The effect of these condensers is to by-pass the sudden pulsa- tions that make interference noises. provided the source can be located. In a large apartment house, for instance, where many switches are being turned on and off at frequent in- Cases where the _inter- ference is severe may require a more elaborate eliminator. In addition to the condensers, radio-frequency choke coils must be connected in the cir- cuit as shown in Figure 2-b. The condensers provide an easy path for the interfering pulsations, and the choke coils, although they have no appreciable retarding effect on the sixty-cycle current that runs the set, provide a very difficult path. In effect, the radio-frequency chokes form a barrier acro.s a road, with the. by-pass condensers providing a detour around the electrical path through the radio set. The principal source of man-made static is an elec- trical spark, produced at the contact of a switch, at the Hook-ups for eliminator with fil- ter condensers only (a) and with radio-frequency choke coils (b). tervals and other elec- trical apparatus is in use, an interference eliminator will pro- Fig. 3. Two types ot :actory-built interference eliminators. They can be used either at the receiving set or at the source of the interference. VF How an interference eliminator is connected between the wall socket and radio receiver. vide good results if connected between the radio receiver and the wall socket. In cases where most of the interference is caused by one or two pieces of machinery, it is more effective to place the eliminator in the power waring circuit as close to the interfering machinery as possible. According to a recent survey made by the power companies, industrial apparatus is responsible for slightly less than one third of the man-made static. Household appliances, on the other hand, cause about one quarter of this form of in- terference. F THE application of an interference eliminator to the recejver fails to affect a cure, the first problem is to determine the time of day when the interference occurs. This often prcevides a clue to its general source. If, for example, the interference starts at eight o’clock in the morning on weekdays and goes almost continuously or at periodic intervals up to five or six o’clock and there is no interference on Sundays, then almost certainly it is caused by machinery in use in a near-by factory or store. It then becomes a matter of scouting around until the source of trouble is located. Usually the owner of the disturbance-causing apparatus will gladly coéperate. ' Suppose, on the other hand, that the noise always starts in just about sun- down and continues through the evening up to. ten or eleven o’clock. This would indicate that the mech- anism operating an electric flashing sign is causing the trouble. Once located, the ap- plication of an interference eliminator, or a specially de- signed filtering circuit if the sign is a very large one, will eliminate the trouble. If the noise occurs only on one or two nights a week at about ten or eleven o’clock and con- tinues all night and perhaps the next day, it is likely tc be caused by an old-type buzzer rectifier battery charger. Here, too, the remedy will be simple once it is located. ‘lg f | if ry Gale ‘| fi Ne Ae Aq aie | ae | Mt ah

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GRP ACS ¥ SUSIE SS — t yf i if! f ; I Gus Explains POPULAR SCIENCE MONTHLY . Marcu, 1939 § MaRcH 19 **Where ave your chains?” asked Gus. “Never use them,’’ snapped Morri- son; “‘they’re no good.” ay to ait PP say, Why Tire Chains Are Safest And Demonstrates His Point by Using Them to Pull the Car of an Unbelieving Motorist Out of the Mud ““™-’VE been expecting a call like this from Morrison,” Gus Wilson grum- bled to his partner, Joe Clark, as they stopped the Model Garage service car beside an expensive new coach job that was stuck in the mud. “Where are your chains, Mr. Morri- son?” asked Gus, as he noticed the posi- tion of the stuck car. “Never use ’em,” snapped Morrison; “they’re no good.” Gus said nothing. Previous experience with Morrison had shown him the futility of arguing with an obstinate, opinionated rich man. Instead, the veteran auto me- chanic dug around in the back of the serv- ice car and pulled out a pair of chains big enough to go around Morrison’s tires. “So you don’t believe in chains, Mr. Morrison,” he remarked. ‘Now just watch what chains will do for your car.” One rear wheel of the car still remained on the concrete of the highway but rested on a smooth coating of ice. The other wheel had sunk several inches into a bog of half frozen mud at the edge of the road. Gus stretched one of the chains on the ice-covered pavement in front of the up wheel and hooked the end nearest the tread over the tire and around one of the spokes. “Watch it now, Joe,” he said as he got into the car and let the clutch in gently. The wheel in the mud remained station- ary, but the other started to turn, pulling the chain toward it along the ice until a cross link caught under the tread. The links bit into the ice and stopped the wheel from slipping. The bogged wheel started to churn in the mud, but, as the tire had a good tread and the mud had a_ relatively solid bottom, the car crept for- By MARTIN BUNN ward, rolling onto the chain. By the time the chain was completely around the tire the car was almost back on the road. ‘Well, what do you know about that!” exclaimed Morrison in amazement. “I thought all the time that the wheel in the mud was doing the slipping.” “It all depends on the kind of mud,” | GUS SAYS— | UTOMOBILE tinkeritis is a kind of a disease. It’s just the opposite of carelessness and indif- | ference—sort of like the difference | between chills and fever. One man | gets a chill every time he thinks | about doing any work on the car. The tinkeritis chap is always in a fever to do something whether it needs doing or not. He just can’t keep his hands off a monkey wrench or a screw driver and his car is in pieces a good part of the time. The other fellow’s car goes to pieces all by itself, if he doesn’t turn it in for a new one when it starts to rattle. It’s uncomfortable to be chilly and there’s no fun in a fever. Be tem- perate—fix things when they need fixing, but don’t spend all your time snooping around for trouble that most likely isn’t there. Gus explained. “If there wasn’t any ice on the road and the car got stuck you could be pretty sure the wheel was bog- ged in one of those soupy mixtures that simply won’t give any traction. In that case this stunt wouldn’t work. You’d have to put the chain on the wheel in the mud.” “It’s funny I never seem to have any luck with chains,” Morrison puzzled. “T got into a beautiful skid with chains on once, so I decided they weren’t any good.” “Chains do act queer at times,’ ad- mitted Gus. “Trouble is, people think that with chains on, the wheels simply can’t slide; so they jam on the brakes too suddenly or try to go round corners too fast. If you happen to lock the wheels at a point where there isn’t any cross chain in contact with the pavement the wheels will slide on the rubber in grand style; but there’s lots of going where you can’t navigate at all unless you do have chains. Of course, though, you can get along on wet pavements without ’em especially if you let a little air out of your tires. ““ CYEEMS to me,” Gus continued, ‘‘that the cost of a pair of chains isso small that it isn’t worth risking an expensive car without ’em. Every car owner ought to have a pair of chains parked under the back seat. “A fellow I know didn’t believe in chains and he went on a long trip in sum- mer without ’em. One day he got caught in a terrible downpour of rain and he had to make a detour from the main road. He met another car coming the other way that hogged more than half the road. The fellow that didn’t like chains got stuck in some deep mud and stayed there until he hired a farmer (Continued on page 146) PO! sign make boat for idea tha job Sea. being. ] write a the boat photogr: tion wel take the Seascc water, a after all working had bui take you One | signing: rather | for hun If need lakes fo doing si She 1 length first of ft. longs license, easy to doing a She ha may be tom, t two or The lir to kee] was re

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1939 © MaRcH, 1930 3?”” orri- »d.”” a —— — 2 eae FY oD ee eee oe ee oe. POPULAR SCIENCE MONTHLY 75 POPULAR SCIENCE HOME WORKSHOP Articles on Furniture, Models, Toys, Sporting Equipment, and All Forms of Craft Work—Better Shop Methods—The Shipshape Home Sturdiness of construction and seaworthiness of de- sign make the Seascoot a general utility boat. By W. F. CROSBY HEN PopuLtar SCIENCE MONTHLY requested me to write a ‘‘how-to” article on building a small outboard boat for fishing and family use, I had no idea that before I was through with the job Seascoot would actually come into being. I expected to furnish the design, write a few words of advice on building the boat,.and let it go at that. But no, photographs of the boat under construc- tion were wanted, and the only way to take these was to build the boat. Seascoot is now complete and in the water, and it was not so much of a job after all. It took two of us about nine working days, or eighteen days in all. We had built small boats before, so it may take you a little longer. One thing was borne in mind in de- signing: that was to make Seascoot a rather heavy boat, a safe and sane craft for hunting, camping, and fishing trips. If need be, she might be used on small lakes for running over to get the mail or doing sundry other jobs. She was designed to be 15 ft. 6 in. in length for several good reasons. The first of these was because boats under 16 ft. long do not require a Government license, and the second was because it is easy to get planks 16 ft. in length, thus doing away with the job of making butts. She has a beam, or width, of 5 ft. and may be counted upon, with her flat bot- tom, to be more than steady even when two or three people get over to one side. The lines forward were flared out a little to keep down loose spray; and the stern was reversed a little, or given tumble The 15)4-ft. Seascoot has a spacious row of seats in the bow and a large seat in the stern. home, as it is sometimes called, in order to provide plenty of ‘‘bearing’” on the water and to prevent settling when the engine is running. This has resulted in a boat with pleasing and entirely practical lines. In order to keep the boat within rea- sonable cost and to make it easy to build, it was decided that the best form would be a perfectly flat bottom. This is the very simplest construction. In the entire boat there is no place where one has any need to resort to that bugbear of boat building, steam bending. The side planks are run fore and aft, and one man with an assistant can bend them easily in place if they are fastened near the bow first and then bent around the frames, fastenings being put in as the work progresses in order to prevent the board from buckling. The planks on the bottom are put on crossways, or athwartships, as this also is easier to do and is better from the standpoint of preventing leakage. N BUYING the materials, we were agreeably surprised to find that the entire cost was well under fifty dollars. If you plan to build the boat in a cellar, be sure that there is a means of getting it out of doors when it is com- pleted. We started the boat in the cellar and finished it in the garage. Under no conditions plank the boat in a heated place, because heat will cause the lumber to dry out unevenly and will result ulti- mately in an unsatisfactory planking job. Seascoot—A Family Motor Boat yus simple, inexpensive, sturdy out- board motor boat was designed espe- cially for readers of POPULAR SCIENCE MONTHLY by Mr. Crosby, who is a marine architect of long experience and editor of The Rudder. To make sure no problems had been overlooked, Mr. Crosby went a step further and, with the aid of one of his friends, actually built the boat. His instructions, there- fore, can be followed by the begin- ner with absolute assurance of success. The first step was to make a full sized set of sections exactly as shown in the drawing on page 76. With the dimen- sions before us, it did not take long to strike in a base line on the floor and then another line at right angles to it which . represented a center line. A straight piece of wood was used as a straightedge for this work; this and a six-foot rule of the usual variety were all of the tools necessary for laying out. Of course, a pencil with a sharp point was required to draw the lines, so that they could be followed closely. Instead of laying out each section separately as shown in‘the drawing, it was decided to draw each one directly over the other. There are only four of them, and it is easy enough to distinguish between them. In other words, only one center line was used for the lot. Section No. 1 was laid out first. The rule was laid parallel to the base line and the dimension marked off from the center line out to the point where the side and bottom boards meet. This is called the chine, and will be referred to by this name from now on. The 20% and 26 in. dimensions, as given in the drawing, were then marked off. We then referred to the profile drawing and measured up from the base line 234 in. to the chine and from this point on up to the deck line 22 in. above. This gave us the heights of the chine and the deck, and the two previous dimensions were carried over so that they crossed these two, giving us two points of intersection, one at the chine and the other at the deck. The same procedure was repeated on the other side of the center line so that when finished we had simply to connect these points and we had the exact shape at section No. 1. Since all boats are designed to the out- side of the planking, it now became nec- essary to deduct this from the lines as laid down on the floor. By referring to the drawing we find that the bottom planking

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SE em SS ES ; POR Re re tere a o> rue Se 2 te ager A pa 76 is % in. thick and the side material '% in. This meant that we marked off these frac- tions on the lines of this section and re- drew the real section line 1% in. inside for the sides and 34 in. in for the bottom.We now had the shape of the first frame. Two pieces of stock each about 24 in. long were cut for the side frames. This length al- lowed several inches leeway. A third piece was cut next for the cross frame at the bottom, and this was laid exactly on the line that we have just made on the floor. The ends of this piece were then marked carefully with a bevel to conform to the slant of the side frames, and any excess wood was removed. The side frames were fitted exactly to the upper edge of this bottom frame and their bot- toms beveled to fit exactly the angle made by the two sections. A little care during this work will save a lot of trouble later on in the construction. Before joining the two sections to- gether, it was necessary to cut a notch in the exact center of the lower frame for the inner keel. We sawed a short sample of the inner keel material, and using this as a model we marked the exact center of the frame, fastened it securely in a vise, and proceeded to fit the piece snugly. The side frames, too, had to be notched to receive the fore and aft strips that are called seam battens. We divided the side frame into three equal parts, from sheer to chine, allowing for thickness of lower or bottom frame, and notches were cut to fit the material for the seam battens. A model piece was used in this procedure also. We found that errors in laying out the frames could be avoided if all frames were clearly marked with their number and : leect « | SECT. 3 POPULAR SCIENCE MONTHLY Truing up the stern piece and planing the back frame flush with bottom of the stern. Note the inside keel which runs entire length of the boat. Chiseling out the notches in the pine side frames so as to accommodate the two 1 by 114 in. seam battens. The frames can be shaped in pairs to in- sure accuracy and symmetry. their outer edges designated with a large X. The notches for the side frames can be made in one operation by clamping them together in a vise. When all the notches were made, the two side frames and the bottom frame were again laid down on the drawing on the floor and the three pieces fitted to- gether. Another piece of wood, called a bracket, was then fitted to cover the ene “ ¢—TRIANGLE BRACE _KEEL TO STERN 8" CLEAT a" : ; | seer 2 ae SOARING tee, I" = RAISED FLOORING | Seat iF 2° OFF BOTTOM ¥ SEAT | \| 2% 3,PINE SPACED ||| (LOCKER 12 0Z. CANVAS ¥y’ APART all} | UNDER- {COVERED DECK CHOCKS ———_ | (NOT SHOWN) NEATH) INSIDE KEEL — i —— x om -— LOCKER] @ —————_ or | See Bae ee 4 ul IN- | to ” ‘ ONE PIECE de z-3 4-3 * 4 QUARTER. ROUND GALV. 1RON STEM gory BAY } } t | ® AT Selig ln:, € 8 i)! a ia 7 | | | 3 7 = | Sa Rae 0 T ag [| BASE Line * oe eat Be “ jue at ¢ ; 2 ee ES z/| be—---— 3-10 —— topo. 3'- 1% | SECT. 4 |SECT. 3 he 21%" —o —" im — 24%" —l __| SECT. + (TRANSOM) Assembly views of the boat and the four sections at which the side frames are piaced. All of the materials needed in the construction of the Seascoot cost considerably less than fifty dollars. | » * | ee Marcu, ]9; junction and placed to allow plenty of material on each side The grain in this piece should run at an angle of about 45 de. grees with the bottom piece go that when the strain comes it will not split. In our boat a piece was fastened on each side -to make doubly certain that no split would occur. These pieces were fitted closely to the outer edges of the frames and were fastened to the frames with 11%4-in. No. 7 brass screws. Never use iron screws if a boat is to be used in salt water. Each screw hole was drilled 34 in. deep, using a drill slightly smaller than the shank of the screw. Each screw was soaped before it was started. After we were sure that the frame fol- lowed the pencil line all the way around, we nailed a piece of 34 by 3 in. stock BILL OF MATERIALS > No. . Ww Part Pes. Stock a ft sades....\ 5. 6 Cypress or pine.... % 10 16 Bottom and 8 Cypress or k seats..... pine.... 34 10 16 Battens.... 4 Spruce or pine.... % 1% 16 Chines and 4 Spruce or Keels. . .. pine.... 12 @ Frames... .. 5 Spruce or pine.... 1 2 16 Transom.|.. 2 Oak...... 1% «9 + SS eee eae 3 2 Moldings... 2 Oak, %-rd. ... 1 16 Floor, etc... 4 Cypress or pine.... % 3 16 Screws..... 432 No.7 brass 1 in. Screws..... 288 No.7 brass 1% in. Screws..... 36 No.8brass 2 in. Screws..... 120 No. 8brass 134 in. Nails ... lb. Galy.iron 1° in. Tacks . 1 bx. Copper 3 in. Canvas..... 1 12 oz. 50 in. square 2 qts. battleship gray paint for interior 2 qts. yacht white for outside 2 qts. red or green copper bottom paint 1 qt. buff paint for deck, seats, and trim 1 qt. of turpentine 1 lb. marine seam composition 1 qt. aviation glue Assorted sandpaper, No. 2 to No. 00 Brushes These materials purchased in New York City cost less than fifty dollars. MaRCH, ] across th exactly was mar pandy ‘ attached Too n necessity of the fr the cons puilding Exact lowed ii frames. the first The shi that the a little, at the « space tl each fre time | of th Th stern the fle be m: off ar was t bring take screw end | ness the f usua. sary their out : batt was In then with grai: elim scre and and V tral tor call anc anc it 1 or An bee

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QO Amok on Marcu, 1930 across the top to hold the loose ends at exactly equal distances. The center line was marked on this piece also, giving us a handy check. These crosspieces were attached well above the sheer mark. Too much stress cannot be put on the necessity for accuracy in the laying down of the frames, as an error at this stage of the construction will ruin the chances of building a successful boat. Exactly the same procedure was fol- . lowed in laying down all of the other frames. The second frame is larger than the first, but was made in the same way. The shape of the third frame indicates that the sides are starting to tumble home a little, as it is wider at the chine than it is at the deck line. It was necessary to re- space the notches for the seam battens on each frame as we went along, at the same time being sure to allow for the thickness of the planking in figuring each one. The oak stock for the last frame or stern piece was laid over the markings on the floor in such a way that it could easily be marked. The excess wood was sawed off and some of the stock for the frames was taken and screwed fast to the edges, bringing them out flush. These pieces take the ends of the planking because screws hold better in them than in the end grain of the stern piece. The thick- ness of the planking was deducted and the frames screwed to the transom in the usual way. No side brackets are neces- sary here, as the stern piece will take their place. These sidepieces were cut out and spaced for the ends of the seam battens, and the crosspiece at the bottom was notched to take the inside keel. In placing the screws we staggered them so that no two screws would come within 6 in. of each other within the same grain of the wood. This was done to eliminate splitting. In other words, one screw was placed near the right-hand edge and the next one near the left-hand edge, and so on. We now had all the frames and the transom complete, and the next step was to make the piece for the bow, sometimes called the stem piece. It was made of oak and was cut a little over 2 ft. in length and 3 in. square to start with. We shaped it roughly triangular and cut in a rabbet or notch for the ends of the side planks. Another way of doing the job would have been to take two pieces of wood and POPULAR SCIENCE MONTHLY The sections were laid out full size on the floor, one over the other. Although these show as chalk marks in the illustration, a sharp lead pencil was used, as it allowed more accuracy. Putting one of the sections in place. Much of the final success depends on this portion of the construction, as any inaccuracy will throw the boat out of shape. Assembling the pieces that go to make up one of the side frames. Note the section lines laid out on the floor. fasten them together so that the joint forms one end of the rabbet line. Then by chiseling off a little of the other edge, it would have been possible to make a very accurate rabbet. When this work was complete, we set the frames up temporarily at their proper distances and then ran in the seam battens and 77 to go by in notching the stem (in back of the rabbet) for the ends of the seam battens. These were set in flush, just inside the planking line. It was also nec- essary to bevel off the outer edge of the first frame and to remove about half an inch of material on the forward side of this frame. The other frames are so nearly square that it was not necessary to do any beveling. The piece that backs the chine was fitted at this time. This is called the chine log, although it is not any more of a log than the seam battens. It runs at the point where the side meets the bottom from bow to stern. The frames were notched out to fit the chine log. At about this time we de- cided that the work had gone far enough in the cellar and the en- tire structure was “‘untied” and set up again in the garage. It is customary to build such boats keel up, as they are considerably easier to plank in this position. Accordingly each frame was set up at exactly the distance given in.the drawing, 3 ft. 1014 in., and the keel screwed in place. One seam batten was run in on each side and screwed to each frame. At the bow the two ends were brought together into the notches cut in the stem piece and screwed in place. The keel was also screwed to the butt of the stem but not until the proper overhang had been secured—2 in.—as shown in the plans. You will note that the bottom of the boat has a slight ‘‘rocker” to it. In other words, the center is a little lower than the two ends. In order to secure this the stem and stern were permitted to rest on the floor while the three more central frames were lifted off the floor by blocking. The stem and stern tried to rise also but we held them down with braces which ran up to the ceiling. At section No. 2 the bottom of the boat is 234 in. higher (since we are building her upside down) than the ends. The other seam batten was now bent into place and screwed to each frame, to the stem, and to the stern. Although it was not absolutely necessary, we painted the entire framework before pro- ceeding further. Next month we shall complete the planking and finish the boat. I" HALF ROUND OAK MOLDING SIDE PLANKING ¥2" CYPRESS SIDE FRAMES 1"x 2° AT BOTTOM TAPERED TO "xi_ AT .TOP the keel to hold them to- gether. A little cord here and there served to make the structure strong enough to work with. The stem was also set up and the seam battens drawn together in front of it and tied with short lengths of wire and rope. This gave us a guide SIOE FRAME SEAM BATTEN BRACKET CHINE f Borrom Frame’ ey LIMBER HOLE TOLET BILGE WATER RUN AFT TO PUMP DETAIL OF FRAME AT CHINE * BRACKET | SPRUCE OR Y. CHINES 1 X 1% SPR.OR Y.P yj. LIMBER HOLE Z Sw SECTION AT FRAME NO.2 SHOWING MATERIALS Details of the side frame construction and the stem piece. Small holes, often called limber holes, allow the bilge water to flow aft.

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z sm = — i meyns tne F, i alain nena ste oben. —. a nantes =a \ Caer earning to Use Small Lathe Trestle Gate Table of Colonial Design Serves as Object Lesson in Studying Operations Spindle Turning By WILLIAM W. ENERALLY speaking, wood turn- i ing lathes can be divided into two main classes: direct motor-driven and those run with a belt. There is some- thing to be said for and against each type, and the use of either of them is mainly a matter of personal preference. The direct motor-driven outfit usually has only one speed, which for most turn- ing is satisfactory, but presents difficul- ties where large diameter or long work is to be done. If the machine is supplied with a rheostat or some similar device for controlling the speed, you will find that as you reduce the speed you also reduce the power. On the other hand, the direct motor-driven outfit can be made more compact, and bothersome belts and shaft- ing can be eliminated; because of this it is often very desirable for home work- shop use. The belt-driven lathe has the advan- tage of speed control, having as a rule three speeds. This variety of speeds is obtained by means of a stepped pulley; the motor itself always runs at the same rate of speed. With this type of ma- chine you can connect a belt directly to the motor or use countershafting, which can be ut lized to operate other machines. Good turning must al- ways be done with as high a speed as is safe and prac- tical to use, in order that the cuts made will be smooth. Long, thin, extra heavy, built-up, and re- chucked work must be turned at a slow speed. In building the table shown in Fig. 1 first pre- pare the stock, which can be any wood—although mahogany, walnut, or ma- ple is preferred. Run all pieces on the jointer to obtain a face and edge. Then rip these pieces on the circular saw to the approximate width and joint the sawed surfaces. Allow 1% in. at each end for waste when cutting to length. This is done to allow for the holes made by the lathe centers. Step No. 1—Marking the Centers.. On both ends of the various pieces to be bas KLENKE Fig. 2. The tail center should engage the work cuite firmly, but not so tightly as to bind. POPULAR SCIENCE MONTHLY True Fig. 1. The table, which can be made of walnut, maple, or mahogany, could not be pur- chased for less than five to sev- en times the cost of materials. turned draw two diagonal lines; the point of intersection will be the center. An- other method is to set a marking gage to about half the thickness and gage lines from the four sides. On all hard wood it is best to bore a small hole (about the size of the center point) deep enough to receive the point. This eliminates any tendency of the stock to split. Step No. 2—Centers in Place. The two centers on ‘the lathe are known as the live and dead centers. The live center (sometimes called a butterfly center) is the one having blades which grasp the wood. Remove the live center from the lathe and gently drive it in one end of the wood to be turned, so that the point goes into the hole just, bored and the blades enter the wood for about % in. Use a Fig. 3. The height of the tool rest is most important. The edge should be about on a line with the center and approx- imately 4 in. away from the corners of the stock as it re- volves. The rest is moved in as the work progresses. Marcu, 1939 wooden mallet in driving in the center. Step No. 8—Placing the Work in the Lathe. The live center end is placed in position first and the tailstock is moved up close to the work. Clamp the tail- stock securely in place, hold the wood with the left hand, and then screw up on the spindle adjustment until the dead center enters the wood. It must be tight enough to hold the work up against the live center and yet not so tight that the wood will not turn freely when revolved by hand (see Fig. 2). Place a drop of oil on the dead center to avoid friction and the ultimate burning of the wood at the point of contact. Step No. 4—Tool Rest. The tool rest, as the name implies, is for the tool to rest and slide on while the turning is being done. The position of this during the turning operation is most important. Turn the wood so that two opposite corners are on a level. Move the tool rest up close to the wood, allowing a space. between the w ood and the rest of about 4 in., and Securely fasten all ad- justments. The height should be about on a line with the centers. Test the posi- tion by revolving the wood several times by hand. Some wood turners, however, prefer to place it a little above the center line (see Fig. 3). Step No. 5—Roughing Off. If you have M ARCH, 193 RI Thi: talk abo Mo clus Hys the rou sm “Pp,

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1930 M ARCH, 1930 IMPORTANT POINTS in buying RIDING COMFORT This is a shock absorber year! They are talked about—asked about and argued about. Motorists should know the features ex- clusive with Houdaille Double Acting Hydraulic Shock Absorbers* that produce the perfect ride. 1. Patented reservoir, which automat- ically replenishes the fluid. bo ° Patented air vents allowing air and gases to escape, making Houdailles truly hydraulic. 3. Strength and precision make safety valves unnecessary. Resistance in- creases when it is needed most. 1. Single adjusting dial easily reached. When you buy a new car—insist on a rough road ride! A demonstration on smooth pavement means nothing. *Product of Houdaille-Hershey Corporation Houde Engin A DIVISION OF H@UIDAIILILIE-HIERSHIEY corPORATION PIONEERS AND WORLD'S LARGEST PRODUCERS OF HYDRAULIC DOUBLE ACTING SHOCK ABSORBERS POPULAR SCIENCE MONTHLY 79 SHOCK AUSOMDER Insist on a rough road ride eering Corporation Buffalo 4 ae ©1930 H. H.C. aah Eee | eee eer teres wiles peneee! Seappchounsyeansiepgememers Ee th ie all a a cA ill a I le mm BOE TN NON A 4 ah A OA AAR HY oH A : ph ne inn Sd ST RD TON cit ent hottie nheanio eae a ag MN Ne eR oe RY EN IT ree aos SE ae Pos ” 7

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——_ Sa To ~~ gif a 3 at = EE TRE BPA NLR ND PAR LOL OI

80

——— Fig. 4. The gouge is the tool used in the first operation, which is called ‘‘roughing.’’ never done any turning before, it is advisable to do a little practicing on some scrap wood at first. The first tool to be used is the gouge (see Fig. 4). While the wood revolves, gently bring the gouge forward until it is in contact with the wood; and then work the tool back and forth until the corners of the work are all rounded off. The gouge is tilted a little to the right or left, depending upon the direction in which the tool is moving. This is done to throw the chips away from your face. Step No. 6—Use of Calipers. In order to turn to any desired diameter, it is necessary to use a pair of calipers and a parting tool (see Fig. 5). Great care must be taken to hold the calipers at right angles to the axis of the work and to watch that the calipers do not ride on top of the parting tool, thereby prevent- ing them from sliding down in the work- ing groove. There is a tool called the turners’ sizer, which is a combination of a parting tool and calipers. Such a tool is valuable in shops where many pieces are to be turned to the same diameter. The general procedure in spindle turn- ing is as follows: First, rough off all work with a gouge until the wood is round; then use the parting tool and calipers and turn the work down to the largest diameter. Next, cut down on both ends to the length, leaving as much wood at the centers as possible. Then, in turn, part down to the various surfaces, always starting with the largest diameters. Finally, work out the beacls to the required design. While the work revolves in the lathe, do all necessary sandpapering, being careful not to round off the sharp corners. The steps for the construction of the table are as follows: Step No. 1—Mortises. Lay out all mortises. Place the chuck in the lathe with the correct size bit and bore out all mortises, using the spindle adjustment on the tailstock to feed the work into the bit. Then chisel out the mortises clean and true by hand. Step No. 2—Tenons. Use the circular POPULAR SCIENCE MONTHLY saw for cutting all tenons. First place the wood flat and crosscut the shoulders. Then stand the stretcher and rail on end and rip the sides of the tenons to fit the mortises just made. Exercise extreme care in fitting these joints. Step No. 3—The Feet. Lay out the curves for the feet and saw to these outlines on the band saw, later smoothing up the curves on a small drum sander. Step No. 4—The Top. The top is made up of one narrow piece and two wide pieces, and a square edge joint may be used.) First cut and fit the rule joint, working it out on a shaper; or rough it out on the i has two rule joints. (If desired, . Marcu, 1939

two swinging gates.) The top is hj together with back flaps about 34 by 3ip and the top is screwed to the framewor from the underside. Step No. 6—Finish. Clean off all ex. cess glue with a sharp chisel and thoy. oughly sandpaper all parts with No. y No. 0, and No. 00 sandpaper. In previous articles I have given the finish for many different kinds of wood, so now I shall take up American walnyt. For a light finish, apply a coat of the correct color wood filler; when hard, give the table at least three or four coats of thin white shellac, rubbing down each coat with No. 00 sandpaper and the last coat with fine pumice and crude oil (or use common machine oil). If you prefer a darker finish, apply one coat of boiled linseed oil before using the wood filler. Sap wood of walnut js very light in color and may be stained to match the heart wood before doing any finishing. For those who wish ad- ditional information re. garding different finishes, namely mahogany and maple, P.S.M., Jan. ’30, p. 80, and P.S.M., Feb. ’30, p. 88, are suggested as references. If woods are to be imitated apply a coat of water stain or commer. cially prepared penetrat- ing stain. When dry, apply thin coats of shellac.

Fig. 5. The parting tool cuts a groove in the wood, while the calipers check the diameter. Notice how both the tools are held. circular saw and true up the curves with a hand plane. Next place the three pieces together and lay out the oval outline, which can easily be done with three small brads, a string, and a pencil (see Fig. 6). Draw the major and the — minor axis (the two os This is the eighth ofa series of articles in which Mr. Klenke, through the courtesy of various manufacturers, is demonstrat- ing the use of many of the new motor- driven home workshop machines of both combination and single types.

{. 5

center lines). From 0 teteteee os cee 4 MORTISE. & TENON axis, strike two i | " | J points, one on each side, on the major axis, with one half of the major axis as a radius. «Drive a small #

=t———— — cursgoeer || Scares i! 1s ™ % TOP 26:18," HALF TOP VIEW

brad at each of these two points and one : at one end of the LESS minor axis. Stretch mae a string around these three brads (forming a triangle), place a pencil in this loop, and scribe the ellipse. Cut the ellipse on a band or jig saw and smooth the edges. Step No. 5—As- sembly. Glue up the two legs, stretcher, . e e and top - rails first and then glue on the feet. Note that all joints are pinned together with hand- made pins, which are made to extend above the surfaces. (Be sure to insert the

~ |

Fig. 6. Dimensions of table; pivot piece; mortisc and tenon joints held with handmade pins; and the method of drawing the ellipse. |

Makc

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81 POPULAR SCIENCE MONTHLY Makrcu, 1930 1 of a sy of strat- RCA RADIOTRON COMPANY, INC. DIOTRON HEART OF YOUR RADIO SET | Radiotron RCA RA RCA RADIOTRONS ARE THE © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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82 POPULAR SCIENCE MONTHLY Marcu, 1930 How to Use a Soldering lron Fine Points By EDWARD THATCHER amateur craftsman is so little under- stood as the useful soldering copper, or soldering iron as it is sometimes called. For fine work, there is really no sub- stitute for this tool. It has the advantage of applying the heat and the solder within a limited space and does not warp small pieces of thin metal as does the blow- torch. The choice of the size of the soldering copper depends on the type of work to be done. The copper must be large enough not only to supply sufficient heat to bring the solder to its melting point, but also to heat the joint. Dirt and oxide are the great enemies of successful soldering, and because of this it is imperative that the four faces on the point of the copper be clean and bright. It is essential to clean up the four surfaces which form the point with a file or emery cloth (see Fig. 1). In order to use the copper the four faces on the point must be tinned. To do this, apply killed acid (P.S.M., Jan. ’30, p. 120) or commercial soldering flux to each of the faces and place the copper in the fire or over a blowtorch as shown in Fig. 2. Allow it to heat until it will melt soft solder—that is, ordinary bar or wire solder—easily. Remove the copper from the fire and rub each of the faces into some bits of solder which have been previously covered with flux and are resting on a piece of clean bright tin (see Fig. 3). Some of the solder will adhere to the four faces and form a thin coating. It is quite important that the copper be kept at the melting point of the solder during this tinning operation even if it must be reheated several times. Be sure Prrnstesr cr no tool used by the Fig. 3. Remove the copper from the fire and rub each face on a small piece of tin which has been covered liberally with solder and flux. in Handling Bit Skillfully and Making Neat, Strong Joints—Fluxes for Various Metals the Copper Fig. 2. Never neat tne soldering iron to a red heat or it will become bad:y oxidized and pitted. to keep the piece of tin with the flux and solder melted on it, as it will be useful in future retinning operations. After the point has been tinned and while it is still hot, wipe each of the faces on a damp cloth to smooth up the tinned surfaces and remove the excess solder. It is well to keep a damp rag on the bench during all soldering operations. It is also an excellent practice to keep a small wide- mouthed jar full of killed acid on the soldering bench, for if the point becomes dirty or covered with oxide it can be cleansed by dipping it into the acid solu- tion. Some craftsmen dissolve about a heaping tablespoonful of powdered sal ammoniac in a tumbler of water and dip the hot copper into this occasionally in order to clean it. In soldering a lap joint with the solder- ing copper, the hot copper is first charged with solder and moved along on the seam as shown in the upper diagram of Fig. 4. An- other method, shown in the middle diagram, is to cut solder into small bits and place them along the joint. Both the solder and joint are covered with flux. The soldering copper is placed on the first bit of solder and rested there until the solder melts into the joint; then it is moved Fig. 1. Thoroughly clean the four faces of the point with a file or small piece of emery cloth. along to the pellet next in line, and so on. Still another method (shown in the lower diagram of Fig. 4) is to hold a length of wire solder against the copper as it is moved along the joint. Never hold work to be soldered in an iron vise or allow it to lie flat on any metal, as the heat will be drawn too rapidly from the copper and the work. If the work must be supported, place it on wood or asbestos, or use a carpenter’s wooden hand screw to hold the joints together. As to fluxes to be used, copper and brass may be soldered with a borax flux like silver and gold. Steel and even cast iron sometimes can be soldered with Fig. 4. Three methods which can be followed in applying the soft solder to the joint. soft solder if they are first tinned by fluxing them with killed acid and then covering them with a coat of solder rubbed on with a hot soldering iron. Gal- vanized iron and zinc are fluxed with pure muriatic acid, while soldering paste or lard oil is sometimes used as a flux for lead. For convenience in soldering small delicate work, self-fluxing wire solder can be obtained with an acid core. In elec- trical work, rosin is used as a flux, or rosin-core wire solder is employed. One important precaution in soft sol- dering is never to heat the copper to a red heat, as this will burn off the tinning and oxidize and pit the working point. — T

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Marcu, 1930 POPULAR SCIENCE MONTHLY The Newest Development in River Transportation— THE CATERPILLAR TOWBOAT And It Runs on the Highest Priced Bearings in the World Qs even the old Mississippi River steamboats that according to legend could sail ‘fon a heavy dew’’, a new type of river boat that dispenses both with propeller and paddle wheel, now navigates shoal streams upon the caterpillar prin- ciple... ALSO upon S3{SfFP Anti-Friction Bearings. For throughout this revolutionary type of boat ...on the caterpillar drive...on the transmission system...are G&S Ball and Roller Bearings... 37 of them...selected on the basis of unfailing per- formance... certainly not upon the basis of price ...for SR0SF is “The Highest Priced Bearing in the World.” SKF INDUSTRIES, INC. 40 East 34th St., New York, N. Y. The unusual method of propulsion employed on the “‘Sunco -A4”’ introduces the caterpillar prin- ciple to water transportation. None but Sis Bearings are used in the drive and transmission systems. THE HIGHEST PRICED BEARING IN THE WORLD

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Hechahdiien F THE caris kept in an unheated garage, a motor cover arranged as shown in Fig. 1 will promote easy starting in many Cases. Of course it will do no good if the car is not used for days at a time, but if it is operated daily, enough heat will remain in the motor over- night to make it start easier. Usea wooden frame from which to sus- pend a very thick hood cover made of old blankets and quilting. The counterweight should be heavy enough so that the cover will stay either down or up as desired; in other words, it should exactly equal the weight of the frame and the hood cover. Insulating the Floor Figure 2 illustrates a simple and inexpensive way to insulate the floor and help to keep the car warm. Sheets of corrugated cardboard cut from large packing cartons should be cut the right size using the floor mat as a pattern. Two or more layers will prove effective as heat insulation and, in addition, the noises that get into the closed body by way of the floor boards will be very noticeably reduced. A Tin Can Cut-Out An easily built and effective motor cut- out can be constructed from an old in can and other discarded parts, as shown in Fig. 3. Remove the exhaust pipe and ” 3 TI Zn Y; WX , = Yi) FLOOR MAT CORRUGATED INSULATING MAT Fig. 2. Insulating corrugated cardboard fitted in place under floor mat keeps the car warm. = CuT-OuUT f HANDLE WR K_ ll ECT! - = Mac, SECTION A-A Well BOARD A HOLE a oF 5 a | EXHAUST TIN CAN aA PIPE Fig. 3. How to make an effective motor cut-out, using an old tin can and other discarded parts. POPULAR SCIENCE MONTHLY ) a Fig. 1. When the car is put to bed, this thick hood quilt, lowered from the ceiling as shown, keeps the engine warm. Each month POPULAR SCIENCE MONTHLY awards a prize of $10, in addition to regular space rates, for the best idea sent in for motorists. This month’s prize goes to A. E. McCall, Seven Springs, N. C., for his suggestion for a tin can cut-out (shown in Figure 3) for a moter. cut a large hole in it. Cut holes in the ends of the tin can so that it will slip over the pipe. Fit one bolt as a stop and another for the spring that pulls the can back over the hole when the valve stem on the end of the cord is allowed to slide into the hole in the dash. The hole in the exhaust pipe can be cut most easily by saw- ing a V-shaped notch in the pipe with a hack saw. Notch area should equal pipe cross section. A Carburetor Control Considerable gas can be saved by keep- ing the carburetor set to the thinnest mixture that will give steady running. The hand control shownin Fig. 4 makes this possible. It is made from a discarded speedometer shaft, a brass collar, and a brass wheel from a toy construction set. The collar couples the lower end of the © CARBURETOR — Fig. 4. This hand control enables the driver to set the carburetor at the right mixture. WHEEL Marcu, 1939 ks for the Car Owner shaft to the needle valve and the brass wheel serves to turn the upper end. Getting Out of a Rut In localities where dirt or gravel roads are common, deep ruts with perpendicular sides will form during the freeze-and-thaw period of late winter. When one motorist meets another, both traveling in the same set ‘of ruts, a pair of wedge shaped blocks, shown in Fig. 5, will facilitate climbing out to make passing possible. Size and angle depend on local conditions. Thin boards nailed together can be used. Automatic Garage Light A stop-light switch fastened to a beam and connected into the light circuit as shown in Fig. 6 will pro- vide an automatic light for the garage. When car drives into the garage its front wheels switch on the light at the ceiling. A cord to the lever of the stop-light switch should be fastened to a board hinged to the floor in such a way that the front tires rolling on to it will pull the switch to the on position. A push button switch is included in the circuit, of course, to provide a ready means of turning off the light. If the weight of the board will not allow the spring to pull the switch up to the off position, use a suitable counterweight. STOP-LIGHT SWITCH Ss SS WIRE OR CORD “ss 6S INCLINED BOARD, 12x 8"x 6-0 —_— dd ae Fig. 6. When the car rolls into the garage, the front wheels turn on the electric ceiling light. DOTTED VIEW OF WHEEL TURNED WEDGE BLOCK DEEP RUT Fig. 5. A pair of wedge-shaped blocks like thi helps the automobile climb out of a deep rut. Marc!

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L930 oe ae a ee Marcu, 1930 When we ask POPULAR SCIENCE MONTHLY 85 motorists, one fact stands out above all the rest- “the New Mobiloil lasts longer We first proved both on the speedway and in the laboratory, that the New Mobiloil would stand up better and last longer than competing oils of similar body. Then—after this new oil had been used by motorists every- where and under every driving condition, we dispatched special investigators to ask motorists this one question: *‘What is most noticeable the New about the performance of the New Mobiloil in your engine?” Almost without exception they replied, “Mobiloil lasts longer.” Thus Mobiloil users add the conviction of everyday, run-of- the-road driving experience to our statement, that continued use of the New Mobiloil will keep that first-year feel in your engine. It is an established fact that in comparing oils of similar ti, “body,” engineers have proved : that the oil which lasts longest, also lubricates best. There is a Mobiloil dealer - near you. He offers you a grade of the New Mobiloil especially produced with your engine in mind. His copy of the Mobiloil Chart will tell you exactly which grade you need. VACUUM OIL COMPANY Makers of high quality lubricants for all types of machinery Mobiloil

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ere — 0 ae val Tee al Saas tai lt Bas Sa —- te a FE 2 ogy ha ADE as SSS ee 8 SARC » Seis? ce Seo aes OE EES The author at work assembling the body of his Diamond Tally-Ho stagecoach model. HILE the trail-worthiness of the Diamond Tally-Ho—that famous old stagecoach which years ago swayed on leather springs and rocked back and forth in rhythmic fashion over the rough road from San Diego to the small town of Julian in California—depended on the sturdy construction of the carriage, all the romance of gold mining days was sym- bolized in its brilliant vermilion body. It is this colorful body that makes the model of the coach so picturesque an ornament. With the completion of the carriage (P.S.'M., Feb. ’30, p. 77), we come to the construction of the body and the means of supporting it. Three blueprints with full size draw- ings (Nos. 115, 116, and 117) have been prepared for those who wish additional details of construction (see page 108). BRACKETS. Front: Anneal a 7-in. length of 4% by % in. brass and fold it in the middle around a No. 14 escutcheon nail, pinching the loop close to the pin. Bend the upright, shape the legs to fit over the bolster, and cut it to length. The third bolt lug is added in plastic wood which is carved to shape after it dries. Rivet this to the bolsters with No. 16 es- cutcheon pins placed so their heads are to the front. The horizontal S-shaped braces are made of No. 11 copper wire and have eyes on the ends. Copper wire (No. 8) is used for the oblique brace, and is split at one end so that it will spread into the fork that clasps the perch. The other end is flattened and drilled for a No. 14 pin which passes through POPULAR SCIENCE MONTHLY Building the Body of the Diamond Tally-Ho By EDWIN Marcu, 1930 M. LOVE the upper braces, the cross member, and the lower S-shaped brace and has a nut riveted to its end. The step’plate, which is made of No. 14 sheet metal, is filed thin on the edges and soldered to the flattened end of a piece of No. 11 copper wire. The other end of this wire is flattened and soldered to the out- side of the perch. The other perch is made in a reverse manner. Rear Brackets: These are bolted to the rear bolster and axle. A long eye on the . lower S-shaped brace is held beneath the axle end with two bolts and covers the clip joint. Clevises: Make four for the suspension straps by hammering No. 14 sheet metal to a thickness of 1% in. BODY. Sides: Make a cardboard pat- tern indicating the outline of the side, door, and windows. Trace the outline on a piece of 114-in. sugar pine placed so that the grain is vertical. Square the ends of the door lines across the top and bottom ‘edges so that they can be located after carving. Prepare a vertical center section pat- tern to trace on the ends, and a horizontal Above: The completed stagecoach body with the front and rear platforms attached. Note the three imitation hinges projecting from the door jamb. Left: Use of the block plane and bench hook in smoothing the body sides. Right: The pointed side panels are cut to a depth of 1% in. in the center Portion and taper out to nothing at the edges. AFTER long research and study, POPULAR SCIENCE MONTHLY, for the first time model building, is readers with authentic plans for the construction of a model stagecoach. in the history of presenting its section for maximum bulge and for the top outline. Also gage the ends with a setting of 13% in. from the front. Carve the vertical outside curve, work- ing across the width with a wide chisel and smoothing the surface with a jack plane. Next, cut down the ends for the horizontal curve and smooth to an even curve in all directions, thus forming the top curve. After the inside has been hollowed out cut a 4% by 4% in. rabbet on each end, squaring it with the chord of the hori- zontal curve so as to receive the end pieces. In the original Diamond Tally-Ho the small sashes were raised into recesses above their openings. Carve these re- cesses, leaving a 4% in. thickness of wood outside and groove the window posts with a veining gouge to receive the edges of the sashes. Draw in the panels on the side; a thin stick sprung around suitably driven brads will aid in drawing these lines smoothly. Carve the pointed panels under the large windows to a concavity of %& in. at the center and taper them off to nothing at the edges. At opposite corners of the doors bore ¥-in. holes and cut out the door openings with a coping saw. Fill the notches left by the holes with plastic wood and smooth the edges of the posts and the doors. Glue the doorstops flush with the front, post stops flush with the in- MARCE Dis: ing coo! Ras ting Cah Eve Mil axe wo! fini

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Marcu, 1930 POPULAR SCIENCE MONTHLY 87 ccept This Offer from Disston A New and Better File Handle and «The Disston Saw, Tool, and File Book’? Are Yours for Just a Dime OW Disston brings you the Stronghold File peatedly. Comfortable grip lessens wrist-strain, and Handle, of new design, shaped to fit the hand, helps to make the amateur a better filer. ~ iS) to give better control of the file, to insure more accu- To introduce this improved file handle quickly, rate work. It is easier to apply and easier to use. pjicston will send one direct to you by mail, with . Coiled spring-steel ferrule holds tang of file tightly, “The Disston Saw Tool and File Book,” for 10 prevents slipping. File removed and replaced readily cents. Ready Feb. 15; your hardware merchant can without injury to handle, which may be used re- supply them soon afterward. Mail the coupon now.

**TheSaw MostCarpentersUse”’ The two handiest saws for the home work- shop are the 26-inch 8-point for cross-cutting. and the 26-inch 514-point for ripping. You will need these on almost every job. The popular “D-8” Lightweights cost $3.45. Many Sther styles and sizes to choose from. Files for the Wood Worker Disston Cabinet Files (fine teeth) for smooth- ing and finishing wood surfaces, easing tight coors and drawers, etc. Disston W. Rasps (coarse teeth) for rough and fast cut- ting, enlarging holes, etc. Half-round 8” Cabinet File, 65c. Flat 8” Wood Rasp, 50c. Disston No. 2 Stronghold File Handle. Length 442". Four other sizes made. OR best results, use Disston Files in Disston Stronghold File Handles. Disston Files are the only files made of Disston Steel, the world’s great, cutting steel, which adds stamina, toughness, and long cutting life to every Disston Saw, Tool and File. The daily use of Disston Files, by Disston saw-makers, safeguards the quality of all Disston Files.

Files for the Metal Worker Every kind, size and style. A Disston 8-inch Mill File, bastard cut, is fine for sharpening axes, lawn mowers, garden tools, and general work*in the home and shop. Excellent for finishing metal surfaces. 25 cents each. You will find a Disston File still cutting true, long after another file would be useless. Far longer service, mechanics say, and better service always. Hard, tough, keen, truecutting! For fast cutting, use Disston bastard double- Band Saws for Better Work Disston “Thin Gauge” Narrow Band Saws are 2 to 3 ga thinner, They run better on machines with wheels up to 26” diameter. Saw 9 8” long, 14” wide, 25-gauge, brazed, $2.08. Other sizes in proportion.

cut hand, flat or half-round files. For a fine finish use Disston single-cut mill or taper files. } : For filing your hand saws, you will want to use Coto aee lde 4 Disston Special Extra Slim Blunt Saw Files. /7™. fais #¢ Hold file firmly against metal.to be cut. Allowing file to slip dulls it quickly. Cut on forward stroke, use full length of file, and lift file slightly on return stroke. To control the

- eee . : < = inet eB err trom Ne Rags ln gym tae ge, ome oe ne sae

cut, hold thumb of left hand at point of file. For fast cutting, rest ball of left hand on file. Keep file free from chips by using a file card —_yyoug* slits com- and brush. Oil fileafter using, to prevent rust. _ pressed by ferrule. Disston makes files for every purpose, sold by good hardware merchants everywhere. Ask for Disston! Not only files, but also hand saws, circular saws, and every other type of saw for hand and machine work; hack saw frames and blades, etc. DISSTON Makers of **THE SAW MOST CARPENTERS USE”

For Your Power Saw Outfit Disston Saws insure better work. Cut easier, stay sharp longer. Disston Circular Saws —cross-cut, rip or combination—are to fit any make of machine. If your dealer cannot supply you, write to us for prices. Hints on Using a Hack Saw For cutting pipes, bolts, nails, curtain rods, etc. Strain blade tight. Cut on forward stroke. Disston No. 3614 Hack Saw Frame. takes 8” to 12” blades. $2.10. Blades, 8”, 55c doz.; 10”, 65c doz.; 12”, 75c doz.

Henry Disston & Sons, Inc., Taiadeiphin, U.S.A. (In Canada, address Henry Disston & Sons, Ltd., Toronto, Ont.) For 10cents, enclosed, send Disston File Handle and Disston Book to: Name and Address......... SENT NIE 2s RET S ENE Sot es

Mail the coupon at the right, with a dime or stamps, and get the new Disston No. 2 Stronghold File Handle, 414” size, and “The Disston Saw, Tool, and File Book,” an illustrated manual on the selection, care and use of tools, full of helpful information. © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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| ad The completed coach and its base form an attractive and colorful ornament for the home. side, and put the upper stops ‘n place. The rabbeted sides are made of %-in. maple, two pieces to each side and placed so that the grain of the wood follows the curve. Glue the sides in place with waterproof glue and allow to dry thor- oughly. BOTTOM AND ENDS. These are made of %-in. pine placed so that the grain runs crosswise on the cab. As- semble the sides with temporary cleats on the edges. Wet one side of a piece of ¥%-in. stock to make it pliable, rest the rabbet sides on a prop held in a vise, and nail the bottom in place, wet side out, using %-in. No. 20 brads and drilling part way with a No. 60 drill. Attach the ends in the same way. Glue muslin on the ends and sides above the upholstery, except in the re- cesses above the small sashes. TOP. The top is made of 1%-in. stock and is held in place with brads. Trace the shape from the body, allowing a %%- in. projection all around, shape the out- side, fit the inside to the body, and glue muslin on the underside before placing it. PANEL BARS. These are strips of \%-in. cardboard glued in place. When the glue is dry, give them two coats of shellac and cut the edge bevel. The band beneath the name space is double thick- ness at the center but tapers at the ends to one thickness. MISCELLANEOUS. To support the seat cushions nail a maple rail between the sides, 1% in. from the door openings at each end and with the upper edges 11% in. above the floor level at the center. The door hinges are maple strips notched into the posts with their “y aa joints in a straight line. The door is set around them, fitting closely enough to stay in place. Attach the platform hinges with brads clinched on the inside. PLATFORMS. Front: The sup- porting bars and footboard are made of maple, while the rest of the sheathing is made from \%-in. | pine. A half-round bar covers the footboard joint beneath; and a curved one, which is thicker at the back than at the front edge, covers ‘g the top. Add the two step irons S with the strap eyes, glue thin card- _ —*,> = t board straps above and below, and * ) CARVE SIDE FROM If SUGAR PINE AND TOP FROM WHITE PINE GLUE MUSLIN ON UNDERSIDE BEFORE NAILING 8} — 4-3 5 | met 1 Ula Willi 1! ‘yt i | CENTER SEAT \\ So ‘ Saee oN tite — 6 ———F 7) Geo over POPULAR SCIENCE MONTHLY LEATHER COVERS (wiREs) (SIDES AND BACK) TOP RAILING Marca, 1939. LEATHER STRAPS AND CURTAINS TRIANGLES LEATHER BOOTS (BOTH SIDES) CARVED 7A PANELS — Opp DOORS, 2% x6 Attaching the footsteps to the metal brackets which hold the ends of the strap leather suspension springs. pine and has % by % in. bars forming the frame. The rear end bar projects % in. beyond each side and has round ferrules made of thin metal or cardboard. Drive 34-in. brads through from below, and bend them into eyes to accommodate the chain hooks. Two cross braces made of thin metal, and the %%-in. No. 14 hinges made by bending an end around a brad, are added next. The top frame is made up of two % by 34 in. crossbars with three % by % in. bars glued lengthwise. A thin cardboard strap is bolted in front and along each side. SEAT. Drive brads through the maple seat board and into the ends, and from the inside of the body into the seat and ends. Underneath, and inside the ends of the seat, glue the metal strips which terminate in the strap triangle eyes. The braces are made of radio a } _ CARVED LINOLEUM | COVERED WITH | j VELVET Ue LEATHER Gime LINOLEUM FORM 2 no FOR NAILS hi) 7S put the bolts and nuts in place. Rear: This is made from %-in. CLEVISES (FOR SUSPENSION STRAPS) - OVER-ALL LENGTH 1-6 4"— 1 ( wioptH 7 ho TAPER TO ONE CELLULOID PANE é ' P ‘ ee Be NO. 16 METAL, FILED ROUND OUT. SIDE BETWEEN LUGS (THESE BARS AT FRONT ONLY) ( 7 FRONT / PLATFORM Perspective of the coach body showing the general construction of the platforms, seats, doors, and wire railing on the top. bus wire and have eyes at the lower ends. Brads headed with nuts are driven through these eyes and into the ends of the seats. The upper ends of the braces hook into holes placed in the roof. TRIANGLES AND RINGS. Wind wire on a rod of the size and shape desired, and cut through one side of the turns, preferably with a jeweler’s saw. To open a triangle or ring, grasp it with two pairs of pliers and twist it sidewise. To close, reverse the operation. Next month we shall complete the directions for building the Diamond Tally-Ho by giving sug- gestions for upholstering and deco- rating the model, along with in- structions for providing the miniature stagecoach with an attractive mounting. All of the carriage building terms which are not self-explanatory are clearly marked on Blueprints Nos. 115, 116, and 117, which contain — full size drawings. In mak- ing so complicated a model as this, full size drawings are essential. Plans for a picturesque covered wagon and for other coaches will be prepared if readers are sufficiently interested in models of this type. What is your particular preference— a covered wagon, another coach, a one-horse chaise, a Mexican oxcart? If’ you prefer to build ship models, please mention the specific ships or class of ships for which you wish plans. Address correspondence to the Home Workshop Editor, PopuLarR SciENCE Monrtaty, 381 Fourth Avenue, New York. S END OF BRACE IN TOP LEATHER = .NO.20 2% Ry Gxb.no.54 DRILL (2 REQ) LEATHER SIDES ARE GLUED BEHIND SEAT ENDS, AROUND STRAPS, AND HELD BELOW WITH Aad” METAL STRAP / Y o 4 ¢ —— , &x& HINGE, Secureo — ae NO:8O. BRADS CLINCHED (4 REQ.) ‘ Dimensions of the body and de- tails of the window frames. Full size drawings can be obtained by sending seventy-five cents for Blueprints 115, 116, and 117. Marcu, Stud Ciat! unu beer look get self to j pro and

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930. Marcu, 1930 STUDEBAKER PLEDGE PLAN OWHERE in the used car market will you find a fairer, squarer basis for used car sales than the famous Studebaker Pledge Plan. More than 150,000 people, appre- ciating this fact, bought Pledge-backed used cars last year. When you buy a Pledge-backed used car, you invest in unused transportation. Most cars sold on this plan have been repainted, refinished and reconditioned to look and perform as well as they did when new. Under the terms of the Studebaker Pledge, you get five days’ driving trial to determine for your- self whether or not the used car you select is suited to your needs. On all Certified cars, the Pledge provides a 30-day guarantee for free adjustments and replacement of defective parts. And all Pledge- STUDEBAKER |- Builder of Champions POPULAR SCIENCE MONTHLY 89 1 2. © 1928 The Studebaker Corporation of America Pledge to the Public on Used Car Sales 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. 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. 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.) — Buy where used cars are sold like new cars-- on the backed used cars carry plainly marked price tags—one price to every buyer! Your Studebaker dealer can show and demonstrate Studebakers, Erskines and other makes of cars in a variety of models. You will find the type of motor car you want—and the kind of protection for your pur- chase that your business sense demands. Invest 2c—you may save $200 Mail the coupon below for the free booklet. A ~ 2c stamp is an investment which may save you as much as $200 in buying a motor car! THE STUDEBAKER CORPORATION OF AMERICA Div. 163, South Bend, Indiana Please send me copy of ‘*How to Judge a Used Car’’ Name State City

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Twenty- -Kive Hints on Using Wire By HENRY TJ IRE, through proper handling and intelligent choice of form, can be used to solve many difficult problems in the shop. Its physical characteristics make it a suitable material for use as tension, tor- sion, and compression members, and for many other purposes which to most of us are less evident. The common metals from which wire is drawn are steel, copper, brass, and alum- inum. Wire is made in dead soft, half- hard, and hard tempers. This must be borne in mind at all times, as the possible uses of different forms of wire depend on their degree of temper. Many things can be easily made from one temper of wire that would be altogether impossible to make from others. Half-hard wire, for instance, is often useful because it can both be readily shaped and will retain the shape it has been given even under con- siderable amount of stress. The approxi- mate bending radii for the different tempers are shown in Fig. 1 at B. Annealed steel wire, especially of the baling wire variety, offers the valuable combination of dead softness with a high degree of toughness, together with the fact that it can be set in the final form by heat treatment. This heat treatment may be of two kinds—stiffening by simply quenching the heated piece in water or in oil, or casehardening, as suggested re- spectively at A and B, Fig. 2. For case- 8 SMALLEST BENDING RADIUS #/G.1 n ‘ = PIANO WIRE — 201AS ~ TIME FORSOAKING | he SX WIRE IN CASEMARDENING A DIA. | TIME REQUIRED O10 | 51015 SEC oa “Ya 101 all # TOS MIN. | c > [SS n Fig. 1. Bending the wire. Fig. 2. Casehardening process. Fig. 3. tive strengths, forms of sockets, and method of Sockets. use. Fig. 4. a= WIRE — ODI” i _HALF-HARD WIRE c= DIA “19s SS WW, \" POPULAR SCIENCE MONTHLY SIMON hardening, it suffices to dip the heated piece into powdered cy- anide or hardening compound, and then to soak it at the quench- ing heat for the amount of time as designated in the table in B, Fig. 2. These values will give a case which will be correct propor- tionally to the thickness of the wire and thus will prevent brittle- ness. With high temper steel wires, heat treatment cannot be attempted, as the strength of these wires, obtained as it is by cold working in the drawing. op- eration, is destroyed by heating, and can- not be restored. N INTERESTING comparison of the strength of various steel wires is shown in the graphic chart in Fig. 2 at A. Many will be doubtful as to the state- ment that the tough wire used in baling, which retains its strength when sharply bent back and forth a dozen times, should only have about one fourth the strength of ordinary piano wire. The fact is that annealed steel wire has ex- treme tenacity but low breaking strength, while high temper piano wire has low ductility but enormous strength: Indeed, ordinary piano wire is one of the strongest things in the world for its size. As seen in the diagram, a piano wire 1% in. thick will sustain the weight of nearly half a ton before breaking. The enormous strength of pi- ano wire should from all reason- ing naturally fit it for many pur- poses of suspension and in the application of a pull where rods and bars would be too large, heavy, or expensive. The rea- sons why it is rarely so used are - to be found in the difficulties of satisfactorily fastening and ap- plying the wire so that any- thing like its strength can be used. The former drawback is overcome by the solder socket shown in Fig. 3, which may be either formed in the part to be pulled as at A, or as an inde- pendent socket as at B. As any good solder melts below 400° F., no part of the strength of the wire is lost in sweating it in place. For a long wire pull, without any appreciable bends or offsets like that shown at C, ordinary screw eyes furnish a satisfactory guiding means. Where a considerable angle must be negotiated, a sheet metal, cast metal, or hardwood sheave like that at D must be used. Figure 3 at E shows an example of a tension device, serving to Rela- Marcu, 1939 A piece of wire coil spring can be used as a core to facili- tate the bending of lead pipe or thin metal tubing, keep a pull wire taut when it is in the idle position. A socket similar to the one just de- scribed will transmit the entire actual strength of piano or plough wire, and is practically the only fastening that will. Cheaper and more conveniently made fastenings are shown in Fig. 4. Though all of them will fail long before any other part of the wire will, they are often more convenient, and far better than the make- shifts usually resorted to. The strongest one is that shown at A, in which the end of the wire is ground off to a taper and the wire bent to a flat loop and soldered. A better looking socket, though one not quite so strong, is shown at B. Similar to B and requiring no solder, but again in- ferior in strength, is the one at C, in which small soft wire takes the place of solder. Finally, a socket requiring no solder is shown at D, where the end of the wire is slightly flattened to give a hold in the en- larged portion of the socket. This con- struction is more quickly made than the solder socket and allows the wire to be readily shortened, though it is not as strong or otherwise as satisfactory. ITHIN limits, piano wire may also be used for transmitting a push in- stead of a pull. One well-known example of such a use is brought out in the shutter reléase used in most cameras. The same idea may be used to advantage in the shop by encasing the wire in a loosely fit- ting soft brass or copper hollow wire or tubing. The arrangement, with clear- ances, is shown in Fig. 5 at A. The bends must not exceed those given in Fig. 3 at D, and the wire should be kept well lubri- cated at all times. The longer the wire and the greater the total curvature it has to negotiate, the heavier should be the tubing or the more frequently should it be supported, as suggested at B. A close- wound piano wire coil spring, as at C, is a good alternative for. the tubing and re- quires no lubrieant. As indicated in dia- gram D, such a wire push device can sometimes be used to eliminate a compli- cated lever system, in addition to form- ing practically no external obstructions. MARCH, !

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Marcu, 1930 POPULAR SCIENCE MON'THLY e Z ud HO tine Nie one ilame tat Catmeillore I Mandy oe SPs ales chet ait, SS nt i AT ap ene hn oe er, Pasay a ee ee sory tn Ba ns a se ae cap Pe i ie hentai tring Rea Ane TeeR ¥ yao eraees ohne THE coupon on this page will bring you the new Starrett Catalog, describing and illustrat- ing over 2500 Starrett Tools, Tapes and Hacksaws. It presents many new tools, many improvements in the tools you already know. @ Your kit isn’t complete without this new catalog. Tear out the coupon; fill it in, mail it today. GOLDEN ANNIVERSARY OF STARRETT TOOLS 1880-1930 © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See Page 8. t

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sopened ~ E Fig. 5. Force transmission. Fig.6. Power soperep transmission. Fig. 7. Wire reénforcing. If piano wire can be used for the trans- mission of a pull or a push, it is no less suitable for torsion. In the form of a plain wire shaft, it can be used for offset transmission of power for use in small drives, as shown in A, Fig. 6, or to drills and reamers as at B. With the wire en- cased as shown in the last figure, the drive MAKE use of every safety device provided in the shop. Always lift a file on the re- turn stroke; dragging it dulls the teeth and scratches the work. When melting babbitt, stir’ in some rosin or oil. This will purify and thin the material and all foreign matter will come to the top. A man who drills holes in the table of a drill press needs to learn something about running a drill. Vinegar is a wonderful help in loosening a rusted screw. Before laying out work, it is necessary to have a definite idea of what the drawing means. POPULAR SCIENCE MONTHLY can be made to turn heavy curves as at C by using either a tube or a coil spring for the casing. On the other hand, matters may be reversed by making a stout close-wound wire spring act as the flexible shaft, while using heavy piano or brass wire as a skeleton in the manner illustrated at D. Such a drive has the advan- tage of requiring none or very little fastening, and also of per- mitting curves of small diam- eter to be negotiated, the form of the skeleton wire giving the required support. Since we have spoken of coil springs for uses other than springs, it may be interesting to mention a few more such uses, lined up in Fig. 7. At A, a screen door spring is em- ployed as a crush-proof pro- tection for small rubber hose or metal tubing. It may also be used for making the hose or tubing stand a heavy internal pressure. At B, the coil spring serves as armor for an electric cable that must be protected from injury. In the illustra- tion at the top of page 90 it is used as the core for bending lead pipe or thin soft metal tubing. A heavy, dead soft copper wire and a close-wound coil spring, sol- dered at one end as at C and D, Fig. 7, make a wonderful combination that can be bent innumerable times to different fixed forms without failure. An alterna- tive combination is a flexible shaft con- struction similar to that of Fig. 6 at C, though with the wire and tube soldered at one end, as indicated at E, Fig. 7. Marcu, 1939 Easily Made Cutter Removes Burrs ALANCE and weight make the burr cutter shown an efficient accessory for the small machine shop. The cutter is easily machined, bei circular in shape and having a ta body and round knurled handle. The cutting edge is formed at a 45. degree angle and is hardened back far enough to allow ample stock for repeated sharpenings. j The clearance (see illustration) should run back at least 4% in. from the 7 and the bottom of the cutter should ground so that it is absolutely flat and square. In use the cutter is placed flat on the work and is moved in a sliding circular manner over the burr to be cut. This gives the cutter a shearing action and makes the cutting easy. The knurled handle and perfect bal- ance of this cutter, together with its weight, makes it easy to operate with a surprising degree of speed and accuracy.— F. J. WILHELM. HARDENED The burr cutter has a 45-degree, hardened, cutting edge on its outer circular surface. Boring a Taper in a Small Lathe SIMPLE and efficient taper boring attachment for use on small lathes can be made with the expenditure of little time and money. The attachment shown consists of a 1 in. diameter steel bar having a %-in. key- way cut along its entire length. A cutter head with a key fastened to its inner sur- face slides on this bar. The key serves to keep the tool always steady and prevents it from turning. A % in. diameter rod is screwed into the cutter head and is bolted to A stop collar is used in chucking the work in order that the taper will start some distance out from the face of the chuck. A hinged joint may be used on the cut- ter head instead of the method shown, if desired. This attachment has been used by the writer with much success and as a mat- ter of fact results have been obtained equaling those of a commercial type taper boring attachment of the simpler type.—CHARLES TOMNEY. a 54 by 1% in. block of steel which is fastened in “the tool post. This acts as a connecting rod between the tool post and the movable cutter head and makes pos- sible the use of the auto- matic lathe feed. The hole in the block is elongated so as to allow the rod to float as the tool post moves away from the bar during the cutting process. The work is chucked as shown and the bar and cut- ter slipped into place and held stationary by the use of two lathe dogs. The tail- stock is then set over to suit ='o SW —— ELONGATED HOLE FOR DRIVING ROD TAILSTOCK SPINDLE KEY FIXED TO CUTTER HEAD CUTTER HEAD (SLIDING FIT ON BAR) u Ny KEYWAY g TOOL REST + 5g's1'4'C.R. STEEL “————— the required taper and the attachment is ready for use. The attachment facilitates the boring of a taper in a small lathe having the offset type of tailstock and no taper attachment. MARCH,

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Chis Marcu, 1930 POPULAR SCIENCE MONTHLY 93 Latest estimates of the total: bus miles operated per day in this country approx- imate five million miles. This tremendous mileage not only requires accuracy in manufacture but also accuracy in maintenance. Skilled mechanics are con- stantly checking the per- formance of every part of the powerful motors that drive these busses. Pistons, crankshafts, cam- shafts, bearings, wrist pins—all must be accurate if they are to stand the grind of exacting schedules. And this huge transportation industry is but one of the many important industries where Brown & Sharpe Tools are used in making important measurements. Wherever accuracy | IBS is required, Brown & Sharpe Tools are chosen for their reliability and improved designs. A copy of our Small Tool Catalog No. 31 will be © sent upon request. Address Dept. P. S., Brown & Sharpe Mfg. Co., Providence, R. L, 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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Smooth Edges ® Quicker! with Simonds POPULAR SCIENCE MONTHLY Marcu, 1939 Tapestry Upholstered Bench By JOHN M. CHITTENDEN OME craftsmen who are H wood turning enthusiasts will find the small uphol- stered bench illustrated an excep- tionally attractive spindle turning project. The construction is not too difficult for the beginner and yet has enough character and grace to make it a worth while problem for the expert. American walnut and Mexican mahogany are well suited for this design, but any wood will serve that is easily turned and that will take a high finish. The legs are first hand-dressed square. A 3 in. thick block 3 in. long is glued to each side 5 in. from one end to form the extra stock for the 234-in. bulge. Make full size tem- plates of one leg and use this in turning the four legs to shape in the lathe. Lay out the rails, marking all joints on both rails and The graceful turned legs of this upholstered bench and or. namental stretchers give distinction to the whole design. oil stain followed by a coat of dark paste filler. Allow this to dry for at least twenty-four hours and apply three coats of shellac, rubbing the surface with No. 4-0 sandpaper be- lees, and _ — coats. When the 34-in. dowels. Pl aner S aws Carefully fit the Brit or MATERIALS shellac’ has’ aviok P rails and legs to- No.of T. W. L. apply a coat of F you could see how quickly gether so that each = mae —s m. nn rub it in and how easily a Simonds joint is tight, as 1 Legs 4 134 134 16% thoroughly. . ; 2 End Rails 21% 4 10% 6 Planer Saw produces a smooth much of the 3 Side Rails 21% 4 20% Stretch three edge on any kind of wood— = on q go 4 Stretchers 4 % 3 12 7 wees , of A yee , ench depends 5 Spindl 1 134 13, 53 er’s webbing you'd want one for your home this part of the 6 Block» 11 % i a between the end workshop ... Simonds P laner construction. Leg blocks 16 3% 2% 3 rails spaced evenly Sawssavelotsof precious minutes The stretchers Tapestry 1 26 36 and placed paral- ..-help you turn out a neater, bet- can be brought to Webbing | 7 yd. lel to the side ter fitting job. Because they’re shape with a hand Cotton batting 2 |b. rails. Next, stretch coping or turning five lengths across made of high quality Simonds steel you can depend upon them for long service and genuine sat- isfaction. Ask your regular dealer to supply you, or write for prices and detailed information. SAWS FILES aan STEEL saw or a motor- -driven band saw, if one is available. Drill for 34-in. dowels and assemble with the 1% by 3 in. square block as shown in the plan at the bottom of this page. After testing all of the joints, assemble the stretchers, turn the spindle orna- ment, and complete the construction of the frame. After all of the superfluous glue has been removed, give the bench a coat of \ \ the bench, inter- lacing them with the others. Where one strip crosses another, several stitches should be taken with twine or heavy cord to add to the strength of the seat. Cover this webbing with an even mat of cotton batting, carefully arranged so as to form a well-rounded seat and to cover all sharp corners on the legs and rails. Over this stretch a piece of muslin and pull it tight around the rails, where it is held in place by driving tacks in the underside. Cut the tapestry at the corners so that when it is sewed it will MaRcH, Q | SECTION VIEW %, CORNER k form a slip cover 14 by 24 ve ihe Fae in. and deep enough to cover the rails and allow extra for use in tacking. - The bottom of the seat l » can be covered with a 14 - : b%——— 10% 9 piece of black muslin. Tho [E o_ ER. 114" NO. 10 SCREWS, guns FURNITURE can be washed with a cloth wrung out in castile soap suds. Use lit- tle water and dry the fur- id ES = g = niture thoroughly. Liquid - SIMONDS SAW AND STEEL CO. 2 | eT ae jie. Se - soiled furniture, liquid akers ablished 1832 Sinn tentitens, Meet on tn ontiie ' cleansers are obtain- Branch Offices and Service Shops in P rincipal Cities ane ties Ge ae wre tag Bas yg gn able. eee earn FERRI ete RRR NON ARN - in rIS} This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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Marcu, 1930 POPULAR SCIENCE MONTHLY 95 Heavy, rough castings are fashioned into machine parts. Thousands of small and large units are finished to accuracy limits measured by tenths of a thousandth of an inch. Many types of grinding ma- chines employ many thou- sands of grinding wheels — reducing and finishing metals NORTON COMPANY WORCESTER, MASS. at lightning speed. Refractories~Floor and Stair Tiles

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96 POPULAR SCIENCE MONTHLY Doctor Finds Home Workshop Restful After Day’s Work Marcu, 1939 a ar aT OS ~ farm Ds oma Lilt sil RE GI TDM EE bia A Cat - © Te microscope told us... Our experience proved it .. . VALET ts a better blade... ° INE out of our 10 research N men use the Valet blade because its remarkable shaving quality bears out the findings of the microscope.’ The Detroit Testing Laboratory, Detroit, Michigan. Men who know steel prefer the Valet— and those who know faces prescribe it —because this remarkable blade proves its superiority both in the laboratory and bathroom. Triple-hardened Valetite- processed steel finished to a micro-edge assures a degree of uniformity impossible to attain by the usual process of manufacture. The new Valet, ideal for stropping is always ready for use without stropping. Try it in the scientifically designed AutoStrop Razor. You'll like its friendly angle, superior shaving performance and unequalled convenience. 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 One end of Dr. C. B. Calbreath’s shop, sh —_ > Sea ne ee owing the main woodworking bench, wood lathe, and woodworking machine. tal and physical play is a necessity in every man’s life. No one should be without some hobby, some means of taking his mind from the everyday wor- ries of a commercial or professional career. The home workshop enthusiast finds mental relaxation in his little shop, tucked away in some corner of the house or hidden in attic or basement. Some shops are large, some are small, but each serves its purpose of supplying the owner with mental play and an outlet for sur- plus physical energy. Each day after long hours of caring for his practice, Dr. C. B. Calbreath, of Hastings, Nebraska, spends some time working in his well-equipped home work- shop. In a letter which accompanied the photographs shown, he said, “I am a practicing surgeon, and nothing rests me more after a hard day’s work than to run down into the basement of my home and work for an hour or so.” In the center foreground of the picture at the top of the page can be seen a combi- nation woodworking machine. This ma- chine can be used as a saw (crosscut or rip), 6-in. jointer, 12-in. planer, hollow chisel mortiser, shaper, emery wheel, dado saw, and disk and cylindrical sanders. The machine is also equipped with a tilt table, thus allowing the cutting of both simple and compound miters. The wood lathe seen at the extreme right of the above pic- ture has a 14-in. swing and is 6 ft. be- tween centers. This size of lathe allows Re etssc piss in the form of men- footstool made by Dr. Calbreath. Dr. Calbreath to doa large variety of work. The main workbench, which is home- made, has a large maple top, oak legs, and walnut drawers. By supplying his shop with the large folding tool chest seen in the background of the picture above and by building drawers under the main bench, Dr. Calbreath has been able to provide pro- tection for all of his hand tools and machine cutters. At the opposite end of the shop from the main bench is a metal working bench, a scroll saw, and a miter box. N HIS spare moments Dr. Calbreath has constructed many fine pieces of furniture, among them the large grand- father’s clock and the Colonial footstool shown in the photograph below. The clock case, which was fashioned from solid walnut, stands 7% ft. high and is 22 in. wide and 18 in. deep. The craftsmanship evident in every line and molding of the clock case clearly indicates the skill with which Dr. Cal- breath utilizes his cabinet-making equipment. The footstool also was made from wal- nut and is in perfect harmony with the antique design of the clock case. If your home workshop has some unusual features, send a photograph or photographs, ac- companied by a brief description of the shop, to the Home Workshop Editor, POPULAR SCIENCE MONTHLY, 381 Fourth Avenue, New York. Five dol- lars will be paid for each photograph found suitable for publication.

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i, 1939 Marcu, 1930 rk. ne- nd ge SOO BE Kw wm 6 POPULAR SCIENCE MONTHLY ust a year old...on Marcn 1.1930 but what a big baby it’s grown to be/ HO ever heard of such an astounding growth in one year? Born March 1, 1929 of distinguished parentage, this prom- ising infant of the Millers Falls family was soon permanently adopted by thousands of experts — carpenters, cabinet makers, crafts- men ... men who know and use good tools. On behalf of the truth it must be stated that the Millers Falls Line of Planes started in life with unusual advantages. Months of careful experimentation by capable engineers, years of experience in fine tool making — these were but a beginning. The result was a line of Planes that improved the good points and elim- inated the difficulties hitherto experienced. Chattering - the age old cause of trouble -— is done away with in Millers Falls Planes. A new feature in Planes - a 3-point bearing of the lever cap — keeps the cutter flat the entire length of the seat and holds the blade firmly at the correct cutting angle. Improved plane cutters which need less sharpening and reconditioning are the result of a profound knowledge of, fine tool steels and a new process of tempering the cutters electrically. Other improvements include extra reinforcements of the bottoms and frogs and a thickness and width of the lever cap - the most frequent point of breakage - which enables you to clamp the cutter as tightly as you want. The Millers Falls Line of Planes is complete, too — bench planes from 7 to 24 inches, smooth or corrugated bottoms, and 21 models of block planes. Ask your dealer to show you Millers Falls Planes. He’ll take one apart and let you see for yourself the unusual improvements which feature the line and what they’ll do for you. We'll be glad to send you a leaflet free of charge showing all the 46 numbers. Write today to Millers Falls Company, Millers Falls, Mass.; New York: 28 Warren Street; Chicago: 9 So. Clinton Street. MILLERS FALLS CABLE ADDRESS: TOOLS MILLERFALL NEW YORK 97 ~ MILLERS Wee os TOOLS + © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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'HE most amazing gun ever invented for target shooting and small game The New CROSMAN REPEATER Silent .22 Tre new Crosman .22 Re- peater uses no powder—yet

it has deadly accuracy and tremendous power. Embodying the most advanced principles of the use of air as power—the new Crosman Silent Repeater is @ real gun that every target shooter and small game hunter should own, use the new Crosman Repeater has all the advantages of any first class .22 rifie plus these exclusive fea- tures: 1. Noiseless. 2. No cleaning. 3. Low cost am- munition. 4. No recoil. 5. Ad power. 6. No bullet splatter. For Targets This beautifully finished repeater rifle is the pride of many a target shooter-—its marvelous accuracy, perfect balance—twenty shot magazine and improved sights together with its other features make is one of the most popular a for all round sport. Men ving in the cities and suburbs ean now enjoy the pleasures of penget ote shooting—in the cellar or yard. Small Game Small game hunters-— you can knock ’em dead \ in their tracks with this high powered silent rifle. You will never use any other small rifle ter you have tried the new Crosman Silent .22 Send for Free Booklet Every man who feels the thrill a

CROSMAN PELL The new Crosman Silent .22 is the dealer or only high powered repeating rifle in -—4, Rees the world that is low. powered by air. Crosman Rifles are built to give life- time service and are guaranteed for one year against defect in workmanship and materials. CROSMAN ARMS CO.

Please send your FREE booklet described above.

POPULAR SCIENCE MONTHLY

Marcu, 1930

<a a Sole Leather Box

This little tooled and embossed leather box forms an attractive container for small trinkets and jewels. By F. CLarKE HvucGHes quality of being worked easily into shape, makes leather an excellent medium for decorative craftwork. A box, such as the one shown, will practically never wear out; in fact, its attractiveness increases with age. Materials needed in the construction of this box can be obtained from the neigh- borhood shoemaker. The leather should be obtained in two pieces, one being 3% by 7 in. for the top and bottom and the other 134 by 11% in. for the sides. When cutting the parts to size and shape, leave the sides a little long to allow for fitting. The design on the sides may be tooled with a blunt awl or a blunt lead pencil after the leather has been softened by wetting it in a | Dic together with the from any thin black leather, though kangaroo or wallaby skin is the best suited. The two parts of the lid, which are mitered and laced together, should be fitted carefully to be sure that they match the main part of the box. The mitered edges will not be difficult for even the unskilled, if it is remembered that the miter is but a 45-degree angle and the diagonal of a square. By gaging a line along the inside the same distance in from the edge as the thickness of the leather, a true miter can be laid out. The box may be lined inside, if desired, with a bit of felt, velvet, or thin lining leather. The outside should be finished with wax or shoe dressing. If colors are desired in the finish, they may be applied as described in the pre- ceding articles on leather work. (See P. S. M., Dec. ’29, p. 102.) /UNE OF HOLES

pan of warm water. A — = number of designs of sim- C4 exreaees| fees pod ae ee

ple form which might be \ ine OF wiTeR

used for these sides are

shown (upper right-hand corner of drawing).

A die made from a piece

of heavy linoleum is used | to emboss the lid. (See

v3 TOOLED VEIN SKIVED ENDS ww Ww, ] NO.S T o_\ Ma mu as . = ——- NAVAYAYATAYA I ai Te C= beCCSC COD [SCOCOCCOCORINS THREE BORDER

P. S. M., Nov. ’29, p. 102.) When all of the parts ° are cut and tooled, begin : with the bottom, or No. 5, and fit and glue the sidepiece No. 4 to this. Either rubber or leather cement should be used, although ordinary glue will serve the purpose. These two parts should PUNCH MARKS (NOT. CLEAR THROUGH)

“STOOLED VEINS ,% DESIGNS FOR TOOLING

fyésae mt DISK OF HEAVY BATTLESHIP LINOLEUM * AS THE DIE FOR EMBOSSING THE LID Ny BLUNT AWL PENED LEATHER TOOLING THE LINES IN THE SIDES WITH A BLUNT AWL

F essndl be allowed to dry thor- ~— he Fale, atm avanti, 8 THE

oughly, after which the et tree SIMPLE STITCH USED ENDS OF SIDES,US-

fac $= FOR LACING EDGES ING RUBBER CEMENT

lining, or No. 3, is fitted

and glued into place. The holes for the lacing

should be punched in the two parts of the lid before EQUAL TO THICKNESS OF LEATHER

the miter is cut. This can be done with either an or- dinary nail set or a regular

leather punch. The laces, which should be about ¥% in. wide, can be cut = SE seth SECTION THROUGH A-A WITH LID RAISED a and can be varied to give any size of trinket box that is desired. PLAN OF MITER

MarR

i Bar & ON MOO BBs Sn de, we

Page 103

Marcu, 1930 POPULAR SCIENCE MONTHLY tools shown above were the first to Le perendoene. They ere familiar to. Try a set. Test them. You will spend big money for such tools, f other tools ‘made by. The Company, watch the Vichek « a ; i © te ped oon eth atl i aca Ba wy nt >

Page 104

Bs CHIPPENDALE MIRROR YOU can make

~™ "a ~ ° ee on Leer a. Et es

" SEM < RS Pr. : es a ¥ = ss aoe a ps Late cae ‘ Pe ee ae = Be ae ay 59 che whee oe Se oe te ete: | Sr ae

“nd

4 SPLY LAMINATEO , | =e srocy % THICK r¢@ || | ae J with the &stertiook COMPASS Laying out the curved outline of this job is best done by rul- ing the paper actual size, into one inch squares, and first drawing in your curves from the diagram free-hand. Then take your Esterbrook Compass and, by changing the radius, plot true curves. Use the Esterbrook compass for the difficult small curves—the larger ones are easy with a pencil and string. The big advantage of ucing an Esterbrook compass on this job is that it stays accurate. Never wobbles, digs, or makes slip lines. Needle and lead are always vertical and parallel. It’s a precision instrument, on a wholly new principle. The radius is shown in inches or centimeter right in sight—on the beam. Small as it is (it comes in a flat trian- gular box 2144"x 314") it makes circles from "to 8” diameter. 50c, at all stationer’s—orsend direct to Esterbrook Pen Co., 80 Cooper St., Camden, N, J.

Ke Using the Esterbrook compass for small circles.

f

The Esterbrook Com- pass with slide reversed EABROOK

Sa

POPULAR SCIENCE MONTHLY

Marcu, 1930

Easily Constructed Wall Vase

_ Made of Hammered Pewter tive metal work, being inexpensive, easy to handle, and attractive in appear- ance. Its advantages will be discovered in making a vase like that illustrated at the right, the construction of which is relatively simple and well within the capacity of a beginner in metal work. The vase as shown was made by E. W. Manzer, who is manual arts super- visor at the Bronxville High School, Bronxville, N. Y.

He entered the design in the elementary metal work- ing division of a shop prob- lem competition conducted by the Educational Depart- ment of PoPpuLAR SCIENCE Monruty and was awarded the third prize. A 2% by 1434 in. piece of Britannia metal (pewter), a pair of tin snips, a file, some iron binding wire, a small piece of emery paper, fine steel wool, and a Bun- sen burner are all that are needed for making the vase. If a Bunsen burner is not a part of your shop equipment, a gas stove can be used, but extreme care must be taken that the metal does not reach its melting point. No matter what means are used for the heating process, it is abso- lutely necessary that the pewter be placed on a sheet of metal so that the heat can be applied indirectly and kept in control. Lay out the design on a piece of heavy paper and after bright- ening the metal, trans- fer the outline to the cleaned surface by means of a sharp point- ed tool. After the metal has been cut to the desired contour, file.the edges and rub them with em- ery cloth tomake them .\/ smooth. If desired, the surface can be enriched by the application of a few hammer marks. The part to be used for the receptacle should be cut and formed next. Take care to make the edges square so that the seam with the back can be fitted tightly. Fit the receptacle in place and wire it firmly to the backpiece with iron or copper binding wire. Be sure that the seam fits tightly and that there are no large WTER is an excel-. lent metal for decora-

The long graceful lines of this wall vase make it an attractive orna- ment for any room.

BINDING WIRE

The portion between the outside and inside lines in the front view may be hammered with a ball peen hammer.

cracks or spaces for the solder to fill. The flux used in soldering pewter is made by mixing 1 oz. of glycerin and 5 or 6 drops of hydrochloric acid. Before applying it, see that the two edges which are to form the seam are clean. Small pieces of the pew- ter can be used as solder or 50-50 solder can be used. If wire solder is used, ham- mer one end of the solder flat and with a pair of tin shears snip off small pieces and place these pellets along the inside of the seam. Place the whole vase on a piece of galvanized iron or sheet of steel and heat the pewter indirectly by applying the heat to the metal sheet. As pewter has a very low melting point, do not under any condi- tion play the flame directly on the pew- ter. If a gas stove is used for the heating, be sure that it is turned down low. As the melting point of pewter is very nearly that of the solder, exceptional care must be exercised in the operation of heating. Solder the little hanging attachment on the back in the same manner, using binding wire to hold it firmly in place during the heating. An easier and just as effective method of hanging is to drill a hole in the center portion of the top. Clean the metal thoroughly with emery cloth and steel wool, and then coat the en- tire surface with a coating of thinned ba- nana oil to prevent the forming of an oxide and the _ subsequent dulling of the polished surface. If desired, this vase can be made of copper, brass, zinc, or common black iron, any one of which will lend itself admirably to the de- sign. Tue ideal vise for home metal work is a swivel hench vise of the machinist’s type having steel jaws from 2% to 4 in. wide: If the vise has an anvil attached, it will serve for light hammering or riveting; otherwise an _old flatiron, or a heavy piece of steel, such as a short section of a rail, will serve as an anvil.

ow.

Page 105

1930 Marcu, 1930 ; POPULAR SCIENCE MONTHLY 101 The Non-Skid screw driver was inserted in the slot of one of the screws holding the license plate, and, with a firm turn- ing = on the screw driver to bind the blade in the screw slot, the car was actually pulled, just as shown here! RIBBED BLADE Prevents Slipping 4h HE new Non-Skid Screw Driver —the most revolutionary improve- ment ever made ina screw driver blade —is so much better that you’ll wonder . wa ‘ line ase why it wasn’t thought of before! > FF Dec. 3, 1920 Take a “chewed-up” screw, securely sunk in hard wood, and just try to turn it with a smooth blade screw driver! It can’t be done! Now insert a Bridgeport Non-Skid—see and feel how the ribbed blade grips. No pushin, no straining —you only turn the Non-Skid. The Non-Skid holds like a gear in mesh. Grips a screw like a non-skid tire grips the road, Drives screws so much easier that you'll never want to see another smooth blade. 3 STYLES Turns screws at almost any angle. Turns All Stzes _battered and rusted screws as though they were new. Turns greasy screws which smooth blades merely “skate” off. Saves furniture and flesh—and a tremendous amount ot time. Lasts longer, because it doesn’t get chipped and worn from jumping and slipping. And the beauty of it is youcan try the Non- q ; j + ‘ql e r] 3 i hy % i i ‘ No. 1 Blade runs clear through — on dmppenney 3 : With a firm turning pressure on onp Chemiedndaatidalts ~ — you buy! Dealers Se pater are che screw driver to bind the blade i i i i in the screw slot, the 6’’ 4 and carpenters. isplaying the new Non-Skid screw driver timber was lifted just on p> he with a demonstration block and screws, so that you can see for yourself what a whale of a difference a ribbed blade makes! Ask your dealer to show you the new Bridgeport Non- Skid today! If he is not yet supplied, order direct: No. 1—4", 50c; 6", 60c. No. 2—4”, © 35c; 6", 45c. No. 3—4%", 45¢; 64", 550. No. 3 THE BRIDGEPORT HDWE. MFG. CORP. Shock nae Bridgeport, Connecticut volts. "Designed expecially The World’s Largest Makers of Screw Drivers for electrical and cabinet é work. Slim blade with 5 Bridgeport CPR pe ane ete as a Foe AG No. 2 Blade, handle and ferrule are riveted securely to- gether. The best screw driver nts pices. THE CHOICE of MEN WHO KNOW TOOLS ris] This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. TRADE ARK PRM 5 a LO Sarre peep te anaieeitea peta ge igterhsy: meee mat ER me aici ee rE ~ fey eee 2s

Page 106

102

IF YOU CAN USE AN EXTRA $20°2° BILL write for this FREE| BOOK|™ OU can save $20.00 in no time by using

-

SMOOTH-ON NO. 1 to do your own household repairing—and in addition you will have that proud “I-did-it- myself” feeling. Here is what one enthusiast did with two 35 cent cans:—A $25 lamp stand loose in base, two big leaks in heating furnace smoke ipe, loose hammer handle, and three loose ooks in tiled bath room wall were all put into good usable condition at an average cost of 10 cts. for each repair—and $20.00 easily saved over what would have been paid to professional fixers or for new parts. By using Smooth-On to make dozens of the simple repairs necessary in every home, you can save enough to pay your radio upkeep, buy yourself or wife a camera, a bull pup or some other pleasure-giving article which you would otherwise hesitate to spend the money for. oa RA

On the Automobile Smooth-On No. 1, being unaffected by water, oil, gasoline or heat, is also excellent for automobile repairs. Try it for stopping radi- ator, tank, pipe line and hose connection leaks from the outside, keeping exhaust line connections tight to prevent the escape of obnoxious burnt gases, repairing cracked water jackets and crank, gear and differential cases, keeping grease cups, lubricator connections, nuts and hub caps from loosening and falling off, tightening loose hinges, robe rails, etc. The FREE Smooth-On Repair Book will show you how an astonishing number of home and automobile repairs are as easy for you to make as for somebody else. Mail the coupor for a free copy and get Smooth-On No. I in 7-02. or 1 or 5-lb. can from any hardware store or if necessary direct from us <<___ 9 Smooth-On Mfg. Co. Dept. 58, 574 Communipaw Ave. te = JERSEY CITY, N. J. Se

Doit with SMOOTHON

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 SRS is SURETY NERDS ERE POPULAR SCIENCE MONTHLY Marcu, 1930

Making a Candle Side Light} By DICK HUTCHINSON lighting fixture illustrated is both practical and easy to build. The bracket, or shelf, is made of 34-in. white pine, finished in gold bronze, and gone over carefully with a blowtorch or similar flame to scorch it and produce an antique appearance. After drilling and cutting holes for the electric cord, the pieces should be assem- bled by first gluing and then nailing them together. Drive the nails from the back so that they will not show on the finished piece. A hole should be drilled near the top to take the hanging cord or nail.’ After the piece is bronzed and burned, it should be lacquered with a coat of banana oil applied with a brush. The sheet brass used for the candle- stick is No. 16 gage, and the piece of 1%- in. brass tubing used for the candle base has a wall of about the same thickness as the brass. The tubing is 1% in. long. With the tin shears, cut a disk of the sheet brass 4 in. in diameter, and smooth up the ragged edges with a file. For hammering this piece into a saucer shape, some sort of a smooth surface steel block, or anvil, and a ball peen hammer will be required. Hold the brass disk firmly in the left hand, placing it on the steel block so that the portion farthest from you is slightly raised, and hammer with the ball end of the hammer, hitting about an inch in from the edge. Drive each blow toward the outer edge of the disk, moving around the piece and at the same time working out to the edge. Be careful, however, not to strike the extreme edge or it will spoil the appearance. Now begin inside the hammered section, and work around to the center, this time driving toward the center. Next, drill a 34-in. hole in the center, two holes for attaching the handle, and \ SIDE from its decorative value, the

yensi HOLE FOR NAIL~. A BACK AND SHELF 34" STOCK

. G

side light. Any close-grained wood can be used for the bracket. Ye x Bx 742" HOLES FOR AT- TACHING TO SHELF ”

This Colonial wall light can be hung from the picture molding or attached with a screw or nail. two more for attaching the saucer to the shelf. Place a piece of iron pipe in the vise, and slide over it the brass tubing for the candle holder. Raise the tubing up until it makes a 45-degree angle with the iron pipe, and hammer a flange on one end with the ball end of the hammer. Re- move from the pipe and place the tube on one end of the steel block and finish the flange from the inside. _ The handle, 54 in. wide and 7% in. long, is hammered on one side and then bent to shape (see drawing). Holes are drilled to correspond with the handle holes in the saucer, and the handle is riveted in place with No. 14 brass es- cutcheon pins. ‘With a blowtorch or other source of heat, bring all pieces to such a heat that they darken slightly; this gives them an antique appearance. Then solder the cup in place in the center of the saucer. Insert a fiber fixture bushing into the hole in the wood bracket and run the end of the drop cord in through this and up through the hole in the center of the shelf. Wire it to the candle socket. Attach the completed candlestick to the bracket shelf with wood screws, n~ 56 HOL and the piece is complete. | A cord may be attached ay 1 * whe and the fixture may be

hung from the picture | molding, if preferred, rather than nailed to the wall. Many old screw drivers give trouble because they constaiitly slip. This is caused by the fact that the point has been ground or filed at too sharp an angle.

Page 107

Marcu, 1930 AN AMAZING IMPROVEMENT IN RECEPTION FROM YOUR POPULAR SCIENCE MONTHLY PRESENT RADIO RECEIVER « WITH NEW EVEREADY RAYTHEON 4-PILLAR TUBES ° THE inevitable jolts and jars of shipment and handling can’t budge the elements in an Eveready Raytheon Tube by as much as a thousandth of an inch. Their accurate spacing, which assures maximum per- formance, is immune to these common hazards. 4-PILLAR TUBES Showing the exclusive, patented Eveready Raytheon 4-Pillar construction. Notice the sturdy four-cornered glass stem, the four rigid supports, and the stiff mica sheet bracing the top. The 4-Pillar construction, which gives Eveready Ray- theon Tubes their remarkable strength, is patented and ex- clusive. With no other tube can you get all its advantages. If you examine the illustration at the bottom of this page, you will see the superiority of this construction. This is especially important in receiving tubes which have large and heavy elements— tubes such as the 224 screen grid, the 280 rectifier, and power tubes used for push- pull audio amplification, re- quiring perfectly uniform characteristics. People everywhere, using Eveready Raytheons in their receivers, report increased dis- tance, more power, better tone and quicker action. To get the most from your receiver, put a new Eveready Raytheon in EVEREADY RAYTHEON each socket. Your dealer has them in all types—including the famous B-H tube for “B” power units. NATIONAL CARBON Co., Inc. General Offices: New York, N. Y. Branches: Chicago Kansas City New York San Francisco Unit of and Carbon Union Carbide UCC Corporation 4-PILLAR SCREEN GRID Eveready Raytheon Screen Grid Tube, ER 224. The weight of the four large ele- ments in_this of tube makes the ex- clusive Eveready Raytheon 4-Pillar con- struction vitally important. © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. 103 eS redial — ate at aie pas Meret re ES 9B BM Se EE I REE EE EGET

Page 108

A sense of real discovery comes to the first-time user of AQUA VELVA for After-Shaving! “Eureka!” (I have found it) cried Archimedes on making a great discovery. The first-time user of Aqua Velva may not cry “Eureka’’. But ina measure he feels it. He has found something—and knows it. He has found what we believe to be the only thoroughly scien- tific after-shaving preparation ever made. Combining in one product all the qualities an after- shaving preparation ought to have. Aqua Velva starts its work with a pleasantly tingling thrill; healthfully livens, wakens, stim- ulates the skin. Cares for tiny nicksand cuts, often unseen. Pro- tects from dust and germs, wind and weather; and, indoors, from undue dryness. Makes for youth- ful firmness ofskin texture. Con- servestheskin’snatural moisture. Made by the makers of Williams Shav- ing oaps, for three generations the Stand- ar which all others have been judged, Aqua Velva seeps the skin all day as the illiams lather Jeaves it, flexible and Fit! 5-oz. bottle 50 cents at all dealers, Or a Free Trial Size ey gedeoceing: Dept. PS10. The J. B. Williams Co., Glastonbury, Conn.—Montreal, Can. Just notice the fine skins of men who use Williams SHAVING CREAM

POPULAR SCIENCE MONTHLY Marcu, 1930

—_——, Two Angle Irons Used to Hold Work to Be Ground B* USING a set of.angle irons having 45-degree grooves cut in them as shown in the illtStration, the grinding of round objects will become a simple matter. When high pieces are to be ground the angles supply a double surface for the pull of the magnetic chuck, and the danger of having the work come loose and begat the wheel is eliminated.—F. J> Wax ; |

Ww 1) The two angle irons provide a larger supporting surface for holding work on the magnetic chuck. Handy Sander for Use on Small Curved Surfaces Pre neg ng and small concave surfaces can be readily sanded by using the small ball sander illustrated. Machine a section of hexagonal stock to the size desired and affix to its end a small wooden ball. This ball is then dipped in glue and fine sand or emery dust SAND OR and allowed to dry. EMERY - The hexagonal F/ COVERED shape of the shaft WOODEN will prevent the BALL pall from turning and will also fit snugly in a three- jaw portable elec- tric drill chuck. EXAGONAL In use,the sander SHAFT is mounted in an The hexagonal shaft electric _ portable fits in a drill chuck. drill and is oper- ated in much the same manner as a router bit. . While glue forms an excellent bond, the writer has had much success with water glass—Appison Du Bots. Simple Joint for Windows INDOWS and screen doors can be as- sembled strongly by the butt joint ii and dowel method . illustrated. Mak- | j

SCREEN DOOR VW) ing the joints in wh this way saves con- SHIT TE siderable time, es- << waits | (i pecially if the mor- ~ ui tise and tenon DOWEL PUT IN joints must be AT AN ANGLE made by hand.—

Dowels are put in the

F. J. PEASE. butt joint at an angle.

No. 6 breas' some The p is ver to ha chang mark mech Calig Hack Dep’ Lath Edge

Page 109

Marc#, 1930 POPULAR SCIENCE MONTHLY Mr. Punch says, “” These four Goodell-Pratt. tools are favorites with men who appreciate fine tool craftsmanship. a 105 owe Mente DALIT Seramnaws oe Parag 0" ela De eR RCRA Tee « i " See them at your hardware dealer’s. No. 514 Hand Drill The most practical hand drill made for all-around use. Capacity to %”. Two speeds — easily changed with Shifter Knob. No holding back when drilling through. Simply shift to ‘“‘Slow’’ speed. Polished Rosewood Handle. Spindle runs in ball bearings. Hollow handle for holding drills. Frame is strong, malleable iron. A comfortable drill to use, A good looking tool that you'll be proud to own. No. 6 Breast Drill How many times have you wished for a real breast drill? One that you could put some “‘heft”’ behind on a real tough job. The price at which you can buy this drill is very reasonable. It will take drills up to half-inch. There are two speeds, changed by turning the Shifter Knob marked “‘Fast’’ or “Slow.” The shifting mechanism is very strong and reliable. — Calipers, Dividers, Micrometers, Hack Saw Blades, Feeler Gauges, Depth Gauges, Electric Drills, Lathes, Levels, Squares, Straight Edges. © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page &. GOODELI a e J ea, wy 8 DLE, Ws alsa » a™% ae - é Mr. Punch This automatic drill carries eight sizes of drill points — 4%" to 114", Pick out the size you want, insert it in Mr. Punch’s steel jaws, place point where you want the hole. You push. He twists. In goes the point and — presto, you have a clean smooth hole in any wood. Also can be used in plaster. Just the tool for house- hold repair work. Remember the name and look for Mr. Punch on the green-covered box. No. 811A Automatic Screw Driver To drive screws with lightning speed or to draw them out just as fast, you cannot find a better tool than the No. 811A Automatic Screw Driver. The shifter knob controls the action right or left and when at “‘neutral’’ the tool can be used as a plain screw driver. Each scréw driver is provided with three tool steel blades, hardened, tempered, and polished. A real handy tool for the home workshop. Wrenches, Pliers, Tool Sets, Repair Kits, Valve Lifters, Carbon Scrap- ers, Glass Cutters, Bit Braces, Mitre Boxes, Nail Sets, Punches. Pe ib iy CNS se = i EA ORAT RET KET naar’ Daa aIS Sheds capt shale ecapaineew takers Mae an pee eel 1 set hp get

Page 110

106 ee ee

Marcu, 1930 fou -

Putting an Edge on a Pocketknife N EXAMINATION of any group of pocketknives probably would reveal] as many different kinds of edges as there are knives. Most of us sharpen knives by holding the blade at a rather large angle to the stone and moving the blade back and forth with a more or less careless rolling motion that eventually rounds off the edge and gives it a shape somewhat similar to the small end of a pear. The impulse to avoid honing the full width of the blade is a good one, but a serious mistake is made in rounding the edge instead of giving it a distinct bevel. To sharpen a pocketkfiife correctly, first hone both sides of the blade on a coarse carborundum or other artificial, stone. Place the stone lengthwise to you,,. ————

This Write a let words, ex a Corona t | will win a prize is $

* C d Ch f D lay the blade of the knife straight <a + ae Lets W the stone, and hold it firmly with the} } each. Lette ap Cc O . eC S C O ra ers finger tips of both hands. Keep the blade | ‘a “to tl . flat and work it down until you have al- 6 A handsome and useful piece most reached the cutting edge. Then| { of reason: —_ a in the o_o way on : _ Corona, r to polish it, still keeping it flat. |e that 7 ou can make ¥y ourself blade is uniformly oul it is then ready | | literary m for the beveling process. or hand-w Complete step-by-step direc- ance that each project and the In applying the final edge to the blade, l tions and dimension drawings’ directions for making it are use either a hard or soft Arkansas finish- Contest cl of all the parts are given on thoroughly practical. ‘Look ing stone or a fine artificial stone. be announ

LePage’s Third Home Work Shop Book, only —_ guide you. The designs, dimen- . To remove any burr, hone the blade | 10cents, ShowsHow to sion drawings, photographs, “ne of mee Jor Le F ho | Very lightly, first on one side and then on }) MakeThese20Projects Step-by-step directions and the ird Home Work Shop the other.— HENRY GEORGE ” actual furniture itself were Book ; : ; Cape Cod Chest of Drawers, Alexandria Nest of Tables, Old Salem Ship’s Cupboard, * Page’s page 3 of LePage’s Third Home Work Shop Book so clearly and simply that any man handy with tools can easily make this handsome and useful piece at little cost— or any of the other attractive, useful projects found in Le- Third Home Work Shop Book or in LePage’s Job Plans. Expert Instruction You have expert instruction to made by William W. Klenke, Instructor in Woodworking, Central Commercial and Man- over the contents of LePage’s book and the Job Plans avail- able as shown in the column at the left. The price of the book is 10 cents. The Job Plans are 10 cents each and are for projects requiring more elabo- rate instructions than. those shown in the Book. In all cases the instruction consists of printed step-by-step directions, dimension drawings of full-size patterns, and a photograph of the finished article. Simply use the coupon below, sending it to us with 10 cents in coin or stamps, and we will With the stone lengthwise as before, place the blade in the second position illustrated below. Raise the back of they}.

blade slightly so that only the extreme edge is in contact with the suri careful to keep the angle and presir@}. uniform, and make each stroke cut evens : Slowly draw the blade toward you. and smoothly from the heel or tang to the point. Turn the blade at the end of each stroke and sharpen against the edge at all times. A few strokes are enough. se

Plymouth Built-In China ual Training High School, New- _ at once send you a copy of this Closet, Lady Washington ark, New Jersey. His expe- latest LePage’s Book, postage (SLIGHTLY BEVELED) Sewing Cabinet, Set-Back rience as an expert gives assur- _ paid. YY) IZZIE Book Shelves, Modernistic Yj yy J VM Z Desk, Modernistic Tubic, PERFECTLY FLAT EDGE Moaernistic Folding Screen, Modernistic Fire Screen, Chess and Checkers Table, Smoking Table, Caned Side Chair, China or Book Cabi- net, Book Trough and Maga- Shelves 34 Sanne Training Work COARSE _| 4 SECTION B-B zine Stand, Magazine Car- 19 oe and_ Reading og Messe Werher’s Teel STONE 3 rier, Vanity Case, Book ee Cabinet = B Stand, Fernery Stand and 20 Colonial Mirror 26 Spanish Galleon oe Sint Folding Sewing Screen. Mail This Job Plans 10 cents Each . . . Order by Number as Indicated in Coupon 16 Sheraton Writing Desk 17 Sheraton Desk Chair 18 Colonial Hanging Book 2t Tea Wagon 22 Telephone Cabinet 23 Stool for Telephone Cab- inet 27 Vanity Table

LePace’s Crart LEAGUE 720 Essex Ave., Gloucester, Mass. Gentlemen: Enclosed please find 10 cents (coin or stamps) in payment for LePage’s New Third Home Work Shop Book. CMLL OUNDED EDGE

SNe

STONE \

SY a

Please send a copy of this book to:

Coupon SECOND POSITION

First / RR OR SEE RE aE, EPS POSITION IEPAGE'S|- p= DI Bhan nsvn nda sviseno tain des OE eee TS opens PERFECTLY GLUE HANDIEST TOOL IN YOUR WORK SHOP"

b] s

: -34(FINISHING ; A BEVEL, THE EDGE. ONLY TOUCHING) Right and wrong types of edges, and two steps in obtaining a keen, lasting bevel on a knife.

Please also send the following Job Plans.................. (indicate by number those you want. See columns above), for each of which I enclose an additional ro cents. 1813 |

Page 111

sac, 1930 POPULAR SCIENCE MONTHLY 107

—_— > Mi. than one million users have learned that Corona is a marvelous- ly efficient typewriter—smooth and re- | Why | want a sponsive in action, sturdily built for a

lifetime of service and an amazing aid to living for every member of the family. | One unique mechanical superiority of : Corona is its one-piece, solid aluminum die-cast frame of tremendous strength

and rigidity. With this powerful frame t > Pp e W rl t e r Corona does not have to be kept screwed to a wooden base— it stands on its own feet, takes up less room on a CONTEST

This contest is open to all. Write a letter of not more than 2CO words, explaining why you want | a Corona typewriter. The best letter |. | will win a prize of $1,000. Second | prize is $250. Ten prizes of $25 each. Letters will be judged accord- ing to the value and soundness of reasons presented for wanting | Corona, rather than according to | literary merit. Letters may be typed | or hand-written. | | Contest closes May 1st.Winners will be announced as quickly as possible. Another advantage—the sheet as typed is held at exactly the right angle for easy reading. Anyone who has used other machines will appreciate this feature. Corona is the product of twenty years’ effort of skilled typewriter engineers to create a perfect small typewriter for per- sonal use. It has everything and does everything. It is small in the sense that a fine watch is small. Working parts are manufactured with exact precision—in some cases to one thousandth of an inch.

ve Fe tent a Ae ae Np EE NE OOP ER nl es EP Oley OE LOLA PN A Pn RN oe ORL BS ate i a a pe AI RN - Mares ¢ nga a oor ee ee - ‘ < wt - = = wee = eee mereee carne a wpa re SR ew PEEP AT See a —— SSS i as - <aeeaiiaieh a —_ _ "2 . felch te mae Sea.sitoa ia aw ae ee een 23 Sirah t sitoee a a + - = , \ Coronas are finished in Scarlet, Green, Blue, and Maroon, with attractive panel- ling of modern design. Also black and gold, and black with art panels. Seven color combinations to select from. There is only one way to know Corona.

Try it in your home. It is easy to Corona- type. In a remarkably short time you can Coronatype faster than you can write. Insist on a Corona demonstration. Any Corona dealer will be glad to deliver Corona on trial. Time-Payment Plan. Fit our conven- ient time-payment plan into your family budget. You can own Corona without even feeling the cost. A few dollars down brings it to you. Then you pay a little every month. Corona with standard keyboard costs $60. Corona Special with three-row keyboard costs $39.50. An attractive carrying case is furnished with either model. An allowance will be made on your old typewriter. Don’t forget the ““Why I Want Corona” contest. Sit down now and catalog all the ways in which Corona will be useful to you, the help it can be in school work, club and committee work, business, writing, home management, correspondence. Ask your local Corona dealer for further informa- tion. Remember, the best reasons for wani- ing Corona win $1,000. L C SMITH & CORONA TYPEWRITERS INC Noel iesnd 1813 New York Life Building, 51 Madison Avenue, New York City our agency proposition.

Page 112

108 POPULAR SCIENCE MONTHLY varnish you dont use that costs

at

anize FLOOR FINISH HOSE who enter our homes—our guests—notice everything, good or bad, about our I surroundings. To our general appearance we can often attribute our success. There- fore, don’t neglect your floors—it costs money in more ways than one. It costs the respect of our guests and it costs far more to replace floors than to varnish them. Absurd, too, when it is so easy to finish floors and all woodwork with beautiful trans- parent Kyanize Floor,Finish. Here is a . varnish of real quality, easy to brush on, flows out to beautiful ridgeless smoothness. Dries in four short hours. Clear uncolored or, if you wish, in a wide range of rich wood l shades from Light Oak to Dark Mahogany. Try this amazing transparent finish on your floors, furniture and woodwork and Save money and friends. Special Introductory Offer!—Just send us one dollar and the name of your favorite paint dealer and obtain a full-pint can of Kyanize transparent Floor Finish, a’ good brush and the new book in colors—“The Colorful Home.” Mention color desired. LOOK AROUND YOUR HOME. ~ YOU i : ~~ gests ‘E a Boston VarRNISH CoMPANY 354 Everett Station Boston, Mass.

Blueprints for Your itive Workshop

O ASSIST you in your home workshop PopuLaR ScrENcE MONTHLY offers lary, blueprints containing working drawings of 4 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 each 15 by 22 in. Popular Science Monthly, 381 Fourth Avenue, New York Send me the blueprint, or blueprints, I have underlined below, for which I inclose Airplane Models 50. 36-in. Rise-off- Ground Tractor 69. Lindbergh’s Mono- plane (3-ft. fly- ing) 82. 30-in. Single Stick ©0 0.68.06 806 $5. Five-Tube i 79. Electric Eis 80. Electric High Pow. er Unit 81. Electric Low Pow. a oS - One-Tu i 98. Two-Tube Electric

86. 35-in. Twin Pusher 87. 30-in. Seaplane | 89-90. Bremen (3-ft./ flying), 50c | 102. Morris Seaplane! (record flight | 12% 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 Foid- 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 ed) operat 54. Five-Tube (battery operated)

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 51-52-53. Clipper— Sovereign of the eas, 75c 57-58-59. Constitution (“Old Iron- ‘ sides’’), 75¢ 61-62. Viking, 50c 63-64. 29-in. Toy Motor Boat, 50c 74-75-76. Santa Maria (18-in. hull), 75¢ 83-84-85. Mayflower (17}4-in. hull), 75¢ 92. Baltimore C (8 in. long) 94-95-96. Mississippi iat ns es Te . 42-in. Racing Yacht, Sea Scout, 50c 66.Ship Model! Weather Vane 108. Scenic Half-Modd | of Barque 110-111-112. Schooner Bluenose, 75¢ | 115-116-117. Concord} Stagecoach, Toys | 28. Pullman Play Table | 56. Birds and Animals | 67. Lindbergh’s| Plane | 72. Colonial Dolls) House 73. Doll’s House Furniture 101. Fire Engine, Sprinkler, Truck, Tractor 113. Lathe, Drill Press, Saw, and Jointer 114. Airplane | with Controls Miscellaneous }3- Workbench | 6. Baby’s Crib and Play Pen 30. Tool Cabinet, Bor- Price 25 cents each except where otherwise noted

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EAD Rie that no without | es are ab conditiot rofessic oak is aint to fasting I mistake “cheap” never b get ama quality them. In selec buyer s the kinc the bris come ci may lo much a compar that the of bris springy safest 1 brush | sponsib Wooste Equal the bri ina b temper brush s just wl

Fig. 1. imitatic stampec handle, Foss-S is a pe cause vise-li power ainti Brush bristle This going ways pe 2 ully Be su

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Marca, 1930 Buy Quality Paint Brushes | POPULAR SCIENCE MONTHLY A Good Brush, Well Cared for, Will Give Amazingly Better Results ena of Popular Science who are expert painters will tell you that no one should begin a paint job without first making sure that his brush- es are absolutely clean and in first class condition. Experience has taught the rofessional painter that a good, clean heath is Just as necessary as is good aint to get a smooth, beautiful, long- asting paint job. Don’t make the fatal mistake of attempting to paint with a “cheap” brush or an old brush that has never been properly cleaned. You will get amazingly better results if you buy quality paint brushes and take care of them. In selecting a quality tool, the brush buyer should give careful attention to the kind, length, quality and fullness of the bristle stock. It is very easy to be- come confused by two brushes which may look alike, but differ in cost as much as 7§c to $1. However, a close comparison of two such brushes shows that the quality brush has a better stock of bristles which are clean, straight, springy, and full of “oily life”. The safest way to pet quality is to buy a brush made by a well-known and re- —— brush company, such as a \ 7 ooster Foss-Set Brush. Equal in importance to the quality of the bristles is the kind of setting used in a brush. Many a man has lost his temper because an apparently good brush shed bristles, swelled,or came apart just when it was nicely “broken in.”

Fig. 1. In order to protect brush buyers against imitation, all genuine Wooster Brushes are stamped with the Foss-Set trade mark on the handle, or metal ferrule. Foss-Set, used only in Wooster Brushes, is a perfect bristle holding compound be- cause it not only holds the bristles in a vise-like grip, but is unaffected by the powerful solvents found in modern — materials. A Wooster Foss-Set rush can be used in anything — the bristles can’t come out!

How to Take Care of Your Brushes This is the all-important thing ach mag are going to get good painting results. Al- ways remember a good brush is a fine tool and must be kept even more care- fully than you keep your saws or drills. Be sure to clean brush thoroughly imme- diately after using. In a few hours the paint, varnish or other material begins to gum up at the base of the bristles and is much harder to remove. Paint .brtshes should be washed clean in benzene, kero- sene, gasoline or turpentine. Varnish brushes should be washed in turpentine, although a first wash of benzene is satis- factory if the final rinse is in turpentine. Shellac brushes should be washed in denatured alcohol. Lacquer brushes should be washed in lacquer thinner, or first in alcohol and then in in lacquer thinner. Kalsomine and fresco brushes are washed in two parts of water and one part of vinegar. They should be hung up by the handles to dry, not laid out flat as paint brushes usually are. When Not in Use A Wooster brush will last you a long time if kept the RIGHT WAY after cleaning. See Fig. 2 for liquid storing. For dry storage, after cleaning ¢hor- oughly, wrap bristles in heavy paper, held tightly by rubber band or string.

THE RIGHT

WAY

Fig. 2. Hang brushes in a can on a line or rod so that bristles do not touch bottom. Keep paint brushes in linseed oil mixed with a little tur- pentine—varnish brushes in brushkeeper varnish.

Get the Right Brush There is no economy in using a “cheap” brush or one that is too small; Paint or hardware dealers who <

a sell Wooster Brushes _— S| can give you expert advice in . selecting the right brush for every paint job. This folder will help you also. See Fig. 3.

Fig. 3. This folder gives helpful hints on the selection, use and care of good brushes. It is sent with every Wooster Test Brush (described in next column) or it will be supplied free on request to The Wooster Brush Co., Wooster, Ohio.

ate 3 I NT A NE ER

109 ence a really good paintbrush makes! Ask your dealer for this famous

Shasta Test Brush (2%" wide). Ideal for-Painting. Var- nishing, Enamel- ing, Lacquering and Staining. Anyone can do smooth, beautiful painting with a Wooster Brush * because Foss-Set —a Wooster proc- ess— perma- nently holds the sleek, springy bris- tles in the brush.

“TED. THE TESTER” onsen: if Zou: dealer does not have the WOOSTER Test Brush, mail this ecoupon with $1. THE WOOSTER BRUSH CoO. Wooster, Ohio Send prepaid, the Wooster Test Brush and information on brushes. [$1.00— not stamps — enclosed] Name Address City Dealer’s Name

© This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. oo eta arena Oe a Sarge aera: este 4 EO AE | 1 |

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110 POPULAR SCIENCE MONTHLY WH SHULL

Dr ‘Richards : hofield 2 eminent doctor of medicine - &expert craftsman owns a ~. @--. home workshop with over a Stones among my best & most important tools-For putting onareally fine clean-cutting edge. Carborundum isjustit” — ~ says Dr: Schofield. THERE are two main reasons why this Car- borundum Brand Stone is favored and used by experienced craftsmen. Not only Dr. Schofield but many thousands who use edge tools. It is known as the ‘‘Combination”’ stone. Really two stones in one. One side is coarse grit for use in starting the edge and removing nicks. Other side is fine grit for finishing the edge. CARBORUNDUM REG. U. S. PAT. OFF. - BRAND SHARPENING STONES Sold by Hardware Dealers Everywhere The CARBORUNDUM Company Niagara Falls, N. Y. Canadian Carborundum Co., Ltd., Niagara Falls Ont. Carborundum is the Registered Trade Mark of The Carborundum Company for its products )

Name 36 Page Booklet P -] Address. On How to Sharpen Tools City. _ State_

Ma RCH, cH 1930

| Handy Rack Provides | How to Remove White Spots: |

Vegetable Storage |

The rack also provides an extra shelf for holdin : canned goods, bread boxes, jars, or milk bo’ EGETABLE racks for the pantry afi kitchen take up little room and allow a quick choice of any of their contents. The rack illustrated is large enough fe the average family and can be made fro scrap pieces of lumber. The writer madi the thirty-two % by 3 by 834 in. slat from lumber salvaged from lettuce craté The piece of veneer on the back of tht rack was taken from an old dry goods box The finish is a question of person choice. However, if the rack is given tw coats of flat white and then finished wit two coats of white enamel it can be easi cleaned and will harmonize with anj color scheme that already exists in th kitchen.— ArTHUR H. ScrIvEN.

‘ PIECES

2-9 FRONT VIEW If a piece of plywood is handy, it can be used to. @ advantage in place of wall board for the back. 7 from Mahogany Tables HITE spots such as those caused by hot dishes on a mahogany table top sometimes can be removed simply by rub- bing them lightly with powdered pumice stone. The idea is to remove the discol- oration but not cut right through the varnish, shellac, or lacquer. Should the spots still show, wipe them with benzine or gasoline to remove every trace of grease and apply a thin coat of shellac—two parts of ordinary shellac and” one part of denatured alcohol—to the spots only. Use a small soft brush for this, or, better still, a spray, and work quickly. Do not go overany part already touched. Let the shellac dry for an hour. If the spots have not disappeared, apply a sec- ond coat, a"'ow it to dry, and then rub 7 it as before.

© 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 111 era Sa See “Yo okt ORS ee rae he Pe a ER ees Pr oe sy vie cd | | RST vais 2 Be ota nen Bee i cre we he Sone Lm a nw Doing Many Big Jobs In American Industry 5 re are many reasons why American Screws have been the choice of industrial executives for almost a century. These i if men know that American Screws can be relied upon to hold units of construction solidly together. American SCREWS are made of high quality steel— their bodies are tough enough to stand up under automatic driving and unusual wear and strain — their slots will not buckle or break — their gimlet points are sharp and true — their clean cut threads are deep and strong. i ves th Sl sna Whether your job is large or small American Screws are the best investment in time, patience, satisfaction and money. Screws are important — that is why American Screws are famous the world over as the best for every purpose. TIRE BOLTS WOODSCREWS STOVE BOLTS MACHINE SCREWS AMERICAN SCREW CO. PROVIDENCE, R. I., U.S. A. WESTERN DEPOT, 225 WEST RANDOLPH STREET, CHICAGO, ILL. "Put It Together With Screws” naa at na i ie at “i lap aie am een Te eee ee “

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| 112 POPULAR SCIENCE MONTHLY Good news for owners of ‘medium sized homes. of your home is of medium size, you can enjoy Williams Oil- O-Matic heating at a new low rice! To supplement the larger Model J Oil-O-Matic used in thousands upon thousands of bigger houses and buildings, Williams has created a new lower priced Oil-O-Matic Junior with ample heating ca- pacity for homesofaveragesize. No manufacturer but Williams— with a decade of experience and facili- ties that have produced far more burners than any other make—could hope to offer this fully automatic fuel oil burner at so low a price. Like the larger Oil-O-Matic, this new thermostatically con- trolled burner incorporates all the patented, exclusive Williams features which make fuel oil heating so dependable and economical. When you get all the facts by mailing the coupon you will banish all heating work and worry from your home. Before you strug- gle with another shovel of coal mail the coupon! WILLIAMS (ILOMATIC HEATING oo WILLIAMS OIL-O-MATIC HEATING CORPORATION BLOOMINGTON, ILLINOIS Branches and dealers everywhere Marcu, 19: WILLIAMS OIL HEAT AT A NEW LOW PRICE HEATING FAR MORE HOMES THAN ANY OTHER OIL BURNER A RADIO TREAT Tune your radio to WJZ and NBC chain stations at 10 o’clock Eastern Standard Time each P. S. M.—3-30 Williams Oil-O-Matic Heating Corporation, Bloomington, Illinois Please send me the revised edition of your illus. trated free booklet, “Oil Heating At Its Best.” Tuesday night. Friday Name. nights at 8:30 Central Standard Time tune in WGN, Chicago. eae Street and Number... o-+-eeee © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. aaa Home Workshop Chemistry Simple Formulas thai Will Save Time = and Money two hours of steady service at a A voltage of between 1.2 and 1.5 and that will recuperate. to full voltage in 24 hours can be peseee -~ ad laboratory for experimental work. | willAight small flashlight bulbs and can | (Ces hours of cells that will give be used for many electrical experiments. | /Eadhs €ell “consists of a wide glass | beaker inside of which is placed a cylin. “« }edfical cup of plaster of Paris. Outside of the cup a cylindrical strip of zinc is placed | and in the cup is placed a carbon rod) which may be taken from an old dry cell. A concentrated solution of ammonium The molds for the plaster cups can be made from heavy paper in the manner illustrated, chloride in water is placed in the outer glass and the cup is filled with a solution of cupric chloride and ammonia. The} latter solution is made by adding am- monia water to the cupric chloride solu. tion until the precipitate first formed is redissolved. Another experimental cell giving from 4 to 6 hours continuous service at 4 voltage of from 1.5 to 2 also consists of a carbon rod, a plaster of Paris cup, anda} strip of zinc. The zinc is surrounded by water containing one or two drops of sulphuric acid. The carbon rod is placed in a solution of sodium or potassium) bichromate in water to which % to y,| its volume of sulphuric acid has been added. This cell must be cleaned after use and freshly prepared chemicals used each time the cell is to be operated. Always remember, when using strong acids, to pour the acid slowly into the) water and stir; never add water to acid. LUTIN, which is prepared from flout, is one of the most adhesive sub) stances known. ° To prepare, place a handful of flour in a piece of muslin and wash it with water, kneading the flour until the wash water is no longer milky from the starch. Glutin remains and should be placed on a glass. dish to dry. To use, take a small flake, add a drop or two of water, and allow it to stand 5 or 10 minutes. Knead it until it is soft and then apply it to the joint. r This glue is adapted to any use, | pecially for leather work.—H. Bape. MaRCcH, A

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Marcu, 1930 _— POPULAR SCIENCE MONTHLY £ SSS ee ores: OR real speed, ease and accuracy in cutting wood or metal, select ATKINS Saws—at your Hardware Dealer’s. He’ll explain why the world- famous “Silver Steel’—used only in ATKINS Saws—takes a keener edge, cuts faster, stays sharp longer, and outlasts two or three ordinary saws. And he’ll show you mary other ATKINS features which saves you time, work and money, : 401’” HAND SAW—“Finest on Earth.” Silver Steel blade, taper ground, ship point, mirror polish, Rosewood handle, Perfection pattern; eliminates wrist strain. “53”? HAND SAW—“A Lifetime Saw for the Home.” Silver Steel blade, taper ground, Damas- keen volish. Regular or ship point. Perfection handle. 465"” HAND SAW—A splendid saw for home, shop or general work. Same as “‘53”’ except it has straight back instead of skew back. “JUNIOR MECHANIC” HAND SAW—Ideal for boys who like to use tools; also a handy saw for grown-ups. 20-inch blade, highly polished. No. 10 HACK SAW—Nickeled steel frame, ad- justable for 8 to 12-inch blades. ‘‘Pistol Grip” handle. ATKINS nonbreakable blades; or our new Silver Steel Blue-End Blades, with real guarantee. No. 2 BACK SAW—Needed in every shop for fine, easy cutting. Rigid Silver Steel blade; 8 to 18-inch lengths. BAND SAWS—In nacevwrwidtha,and any lengths. Made of Silver Steel, for fast, accurate work. CIRCULAR SAWS—Silver Steel. Cross-cut, Rip, Mitre type. Sizes for small shop or portable outfits. CIRCULAR MITRE SAWS—Silver Steel, spe- cially ground for smooth cutting, as in fine cabi- net work, etc. 6 to 24-inch diameters. DADO HEADS—For power outfits. Sizes to cut grooves from % to 4 inches wide. NEST OF SAWS—Three fine saws for one ad- justable handle. Keyhole and Compass Saws; also nail-cutting blade. COPING SAWS—Strong, nickeled frame, hard- wood handle. 64-inch blade, cuts at any angle. SCRAPER BLADES—Silver Steel makes the best scrapers to finish floors, smooth up surfaces or remove paint. All styles and sizes. FILES of Silver Steel, in every size and style, for faster, easier sharpening, filing and finishing. MACHINE KNIVES—of Silver Steel, for small worksho, pianers, jointers, shapers, etc. GRINDING WHEELS—ATKINS Acrolite wheels do quicker, better grinding; all sizes. For these, or any other cutting tools you need, = your Hardware Dealer. Insist on “ATKINS.” 4 Saw Booklets FREE! Send destin Below Fe OER PR ae ty OR | Ec. ATKINS & Co. Est. 1857, 428 South Illinois Street INDIANAPOLIS, IND. . * I ricese ails allied Viena — an om Get 1 these $ Saw Boo FREE| SEND THE COUPON © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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114 rrr EVEREADY RAYTHEON TUBES FOR TALKING PICTURES AND TELEVISION ARE DEFINITE CONTRIBU- TIONS TO THIS NEW SCIENCE EVEREADY RAYTHEON is at the front in television . . . with both transmitting and receiving tubes of proved dependability and per- formance. The Eveready Raytheon Foto- Cell is a long-life transmitting tube for talking pictures, made in several standard types. Also used in television. Foto-Cells to special specifications will be made at rea- sonable prices. The Eveready Raytheon Kino- Lamp for television reception is the first tube developed commer- cially which will work with all systems. Its glow is uniform over the entire plate. Its reproductive qualities are perfect, without the need of mirrors or ground glass. The performance of each tube is carefully tested in our laboratories. Correspondence is invited from every one interested in television and talking pictures. NATIONAL CARBON CO., Inc. General Offices: New York, N. Y. Branches: Chicago, Kansas City, New York, San Francisco Unit of Union Carbide and Carbon Corporation EVEREADY RAYTHEON Trade-marks POPULAR SCIENCE MONTHLY Marcu, 1930 ee Seven Motorized Shop Aids By . RayYMOND B. WAILES ing a motorized workshop vary with the space available, the machines to be used, and the type of work to be done, but there are a few kinks that can well be incorporated in any shop, large or small. Semipermanent machines mounted on wooden bases can be effectively and Pires motor in planning and arrang- “i | | | joi eall nite): | - quickly held fast for connection to the line shaft by the use of C-clamps. By varying the length of these wooden bases, one length of drive belt can be used on any of the machines. The problem of connecting two shafts becomes an easy one if rubber hose and metal hose clamps are used in the man- ner illustrated in the illustration above. This method has an added advantage of working even if the shafts are a trifle out of alignment. The tearing limit of most high-grade rubber tubing is very great and for this reason a large running load can be transmitted. A lathe wrench will never be misplaced if it is fastened to a length of chain which is in turn attached to the underside of the lathe bench. End play in shafts can be prevented by means of pulleys or collars, but BX cable box connectors serve well, and it is easy to screw them tightly to the shaft close up to the hanger. They have the added feature of low cost. Many shops are limited as to the space that can be used for storing tools, buffing rouge, rag wheels, wire wheels, emery wheels, slip stones, pulleys,sanding disks, and many other auxil- iary tools. A small box of simple con- struction bolted to a hinge, which is in turn mounted to one of the legs of the workshop table or bench, is handy for storing anything that is used frequently. The box can be moved A length of chain will keep the lathe wrench where it ought to be. Shaft end play can be prevented by the use of a BX cable box connector. 5 Machines on wooden bases can be rigidly attached to the bench with C-clamps. Shafts can be effectively coupled by means of a piece of hose clamped on as at the left. Handy swinging drawers supply ample space for accessories needed in a hurry. out in an instant, and then turned back out of the way. Extra pulleys are always needed in the motorized shop and form an added item of expense. Wooden driving pulleys can be turned on a lathe, or if extra large ones are needed, they can be turned to shape on a buffing head supplied with an im- provised tool rest placed in the proper position. The blanks or disks can be cut to shape on a jig saw and mounted on the buffing-head shaft. The groove can be cut with a rat-tail file. Wooden pul- leys such as these, if mounted on the buffing head, are very useful in alter- ing the speed of line shafts and other de- vices. Themain driv- tS) This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. MARCH,

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Marcu, 1930 POPULAR SCIENCE MONTHLY This is a Greenfield “Little Giant” Screw Plate Set No. 311... the world’s standard for precision and stamina. This thread cutting set is a joy to the man who has tried to handle threading with ordi- nary tools. GREENFIELDS Small Tool Lines 1 TAPS 2 DIES 3 SCREW PLATES 4 TWIST DRILLS 5 PIPE TOOLS 6 REAMERS 7 GAGES Every he man loves fine tools. The greater his skill, the greater is his admiration for them. And it’s amazing what excellent work even the rankest amateur can turn out with really fine tools. Take thread cutting, for example. The “Little Giant” Screw Plate Set shown above is used by highly skilled mechanics in every civilized country in the world. . “Little Giant” Screw Plates were the choice of the United States Navy’s Round-the-World Flyers several years ago, and of Commander Byrd’s Antarctic Expedition. Men who know and who must have reliable threading tools, always pick “Little Giants.” Put this admirable tool in the hands of an amateur... the man who just uses threading tools occasionally in tinkering around the house, or the garage, or on the farm . .. and he can’t help doing a better job. He finds his threading jobs are turned out easily and with a precision that gives real satisfaction. Good tools make all the difference in the world. Those who use them in quantity know this well. That’s why “Little Giant” Screw Plates and other famous Greenfield small tools are standard equipment in large automobile fac- NEW YORK 15 Warren Street tories .. . in big railroad shops. . . in aircraft plants and in maintenance shops at leading airports — the world over. If you’re a skilled mechanic you probably already use Greenfield small tools. If you do just an occasional job requiring threading or other small tools, you must get acquainted with Green- field quality. You’ll be proud of the work you can do with fine tools like these. Ask your dealer —or write today for illustrated folder with complete information and prices on “Little Giant” Screw Plate Sets . . . or other Greenfield small tools which interest you. GREENFIELD TAP & DIE CORPORATION Greenfield, Massachusetts I’m interested in fine tools. Send me illustrated folder on “Little Giant’’ Screw Plate Sets. Name City State CHICAGO 611 W. Washington Blvd. DETROIT : 228 Congress Street, W. ~ Canadian Plant: Greenfield Tap & Die Corporation of Canada, Led., Galt, Ontario 115 | ith this world-famous set even amateurs can do a precision job! © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. arog ee a ~ roe 3 re rm — HOSS WG TON ROE et BE D5 ae? er aa ne ces as 4 if : # |

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POPULAR SCIENCE MONTHLY Marcu, 1930 Marcu Make Things Quickly and Easily | » Via 7 with _ NE W 1930 Sets of homemade wooden pulleys attached to the polishing head serve as speed reducers. ing belt can always be tightened easily if the motor is mounted on a. slotted wooden base. A screw passing through a slot in the base and then into the table top permits the motor to be brought for- ward or moved backward to loosen or tighten the belt. Small wooden guide rails on each side of the wooden base will prevent any side motion of the motor. 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 Raising Lever to mention but a few. Send coupon for complete description of this re- markable workshop. You will understand then why men who know prefer ‘‘Delta.”’ Wood Used as Emergency : . Bushing for Pulley 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 J 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 iy AN emergency it is sometimes necessary to fit a split pulley to a shaft of much smaller diameter than the bore for which the pulley was intended. This can be accomplished by cutting six pieces of hard maple to size and in- serting them as in the case illustrated, where a 3% in. bore pulley was fitted on a 3-in. shaft. The pieces in this instance measured 4 by % by 6 in. When the maple pieces are set between the pulley and the shaft as indicated, BORE OF PULLEY 3) DIAMETER OF SHAF EASY TERMS ieee il \ For complete details and full description of the new 1930 ue ra | = 3 Delta line, send coupon for FREE illustrated literature. ! =|) Shows many items of interest to those who Sa eae | =i work with wood. You will learn, also, how you DELTA epneea..t¥ COMPANY, Dept: B-330 can try any Delta equipment for 10 days under Division of “Delta Manufacturin d actual working conditions at our risk. Choice 1661-67 Holton St., Milwaukee, wis. of three convenient payment plans. Mail Please send me FREE, illustrated literature describing MAPLE STRIPS coupon TODAY! 1930 model “Delta” Woodworking Units. Also details of 4, x 10-Day Trial Offer and Easy Payment Plans. (Check spe- A F e cial information desired. ) Six maple strips of the correct size are in- Delta Specialty Co. [oi vitiu. Ayrat cee one serted between the pulleys and the shaft ue Combination Ky Setater * ae meg Saw Division of |S eee shop and professional use three on a side, the bolts on the pulley are DELTA MANUFACTURING CO. [| Name drawn up tight. ; Address... In the instance where this makeshift 1661-67 Holton St. Dept. B-330 Milwaukee, Wis. —emmeet | was used by the writer, the pulley worked MODEL SHIPS | | PEAY A MUSICAL SAW | Gi ret show the slightest signs of slip You have heard our “Musical Saw” over the radio ping.—H. L. WHEELER. We can supply construction sets and all sorts on phonograph records, and on the vaudeville FR EX He = stage. It is the easiest musical instrument to play. whorl, capstans. . Sgure theads. blue Drints. Fun for you and music your friends will enjoy. We To ADJUST a bell for use in connection of {he Flying Cloud, Conatitution. | Spanish will send you this Musical Saw with bow, hammer and | with a transformer, the gap at the breaker oo Sever 1 five days’ trial. We will prove that you . . eign of the Seas, Bi Mayfiow ~ essons on five ys rial, e will p yor Many others, Aine speci oy gf re can play popular pieces in five days. No notes to | Points should . made + than it was ier ihe mak makes. Gar teres d read, no dreary finger exercises. No obligation to when used on batteries, because a more in in sddition, peer pps buy. FREE information. rapid make and break is necessary in ny peo only slight'y interest in models have me i I Bale MUSSEHL & WESTPHAL order to keep ahead of the alternations Model Ship Supply Co., Dept. S, Mineola, N.Y. 17 South 3rd Street Fort Atkinson, Wis of the current. @Orthis seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. -

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0 Marcu, 1930 POPULAR SCIENCE MONTHLY 117 ‘ 5 ars fhe CSE WAROCHAN _s ee “The Porter line ‘aches 60 sandr _ Bolt Clippers, _ Shear Cutters, Nut Splitters, Chain Cutters, etc. — "every one an efficient practical tool. Write 4h cata: tog. Ae your jobber. is 6 ° 7 Ashland EVERETT © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. 598 2 ns NRT RSL aN

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REM: PON TREE TY oS

118

surface at one time, an sonable job of sanding.

POPULAR SCIENCE MONTHLY Do your sanding the easy DEER yy This Sturdy DRIVER Belt Sander Complete $5.39

HE “Driver” Belt Sander is unexcelled for quickly putting a straight ood, bakelite, ete.—The flat metal bed under i ish on metal, w i Tecan ih on straight lines and sharp edges—This sander can be used either in an upright or horizontal — and the belt is adjustable— It is far superior to @ grinding wheel f : E i chisels, jointer-blades and other keen edged tools as it grinds the entire ; d does not overheat the work. The “Driver” Belt Sander is not a toy—It is a sturdy—well-constructed machine designed to give maximum service—and guaranteed to do any rea- or shaping metal, and sharpening Available in Parts at Not Over $1.00 Each! As with all other “Driver” Power Tools—lathe bench saw, jig saw, planer, flexible shaft, dado and polishing head—the belt sander can be bought a rt at a time, at our $1.00 limit. Ask your dealer or descriptive circular. ‘ The “Driver” Belt Sander can be used with power tools of other manufacture provided the proper drive pulleys are available. WALKER-TURNER CO.,INC. Manufacturers JERSEY CITY, NEW JERSEY APPROVED BY POPULAR SCIENCE INSTITUTE

TEN MILE EYES! 10 POWER S213 Pr “Cheap at $50” —Says Navy Man Buy Direct—SAVE HALF TEN MILE EYES! Think

Long of the things you can see! Ran Ten mile radius—a 20 mi ge circle — nearly 400 square miles. And you can casily have them. If you can see one mile, these superpower French 10x32mm. binoculars will eutend our stereo-prism 10 vision : Nii a ENIOT Rk Len 10 7 more! Multiply pleasures y and sport. se LENSES a pair touring, o vation, hunting. golfing, nature study. astronomy, ete. Superbly made for a lifetime of service. Case and straps free.

Di k many ordi field glas: have but four lenses and most wt better ones only six? But this binocular has 10 of the better ones only six? ‘ 4 LENSES and 4 PRISMS. No wonder it gives an PRISMS] expansive field, brilliant illumination and fine defini- tion. thout Extra Cost Paying postman balance and ‘ew cents postage. k and com it in every way for five days with others selling for double or more. If you do not like it for any reason whatever your money will be FREE mptly returned. Every glass tested. The U. 8. w't and State Forestry Dep'ts buy from us. T TRIAL same in 8x only $18.50, Surpasses others at $23.50 and CATALOG. ,3%4720Sis32, Everything in binoculars, field glasses. telescopes and optical instruments. The finest and assortment in America. Catalog gives all information how to choose the best for your individual needs at the LOWEST PRICE. Try America’s Leading Binocular House First DuMaurier Co., Dept. 303, Elmira, N. Y. BOYS! “Woney”

instructions any boy erect Grandpa ped louses. They sell at § to n ar’ make money building my famous bird houses. Valuable information about song birds god tine and advice on making sales included GEORGE J. BREIDERT

1047 N. Eimwood Ave., Oak Park, tt.

AN EASIER Way toPopularity PLAY your way to favor with a sweet-toned, -playing Pan- American. You learn popu music quickly. Fun, hopularicy, increased income ! Choose any instrument—Pan-Americans are the only complete line of na- tionally-advertsed, factory guate anteed, moderately priced instru- ments made. Free Trial; write for literature; mention instrument, PAN-AMERICAN Band Instrumentand Case Co, 304 Pan-American Bldg. Elkhart, Ind,

Chemical Tricks for Boys Surprise and puzzle your friends with magic chemical tricks; make ink; dye cloth, test water and soil, write secret letters with invisible ink; pour blue, brown and black liquid from a pitcher of water. All these and many more chemical stunts are easy with Chem- craft Junior. It’s the best box of fun you ever had! Get yours now. ONLY 25c POSTPAID FREE Catalog and Chemcraft Maga- zine t@ every boy who = writes for it now. Full of new ideas and chem-

Gs! ing K€ EB = WS Oe 8) ~. SOCK) Cy ical stunts. Ask for ; Sere cea oe THE PORTER CHEMICAL COMPANY 6 East Washington St. Hagerstown, Md.

Here’s an Easy Way! —to bring you a fine cash in- come! Without taking ary time away from your’ job. Pleasant easy work at home. Decorate beautiful giftwares the Fireside way. You can do it—in spare moments. No previous training required. No special ability needed. No tedious study. No memorizing. With the Three Simple Steps sent you by Monsieur Petit the great artist—Director of _ Fireside = Industries, it is just fun! We want men in every community. Be the first! FIRESIDE INDUSTRIES Dept. 51-C

ADRIAN, MICH. Begin Right Now! _ Thousands are making Fire- side d i making from hundreds to thousands of dollars and doing their own work be- sides. We supply you with everything you need. Big Generous Complete Kit WITH- OUT EXTRA COST. It's a cinch! We absolutely guarantee your success. se 7s EE! | FIRESIDE INDUSTRIES out and Dept. 51-C, Adrian, Mich. mail coupon at once. Without Send me your wonderful Free Book in colors. This does not put me under any

any obligation

it brings you obligation. wonderful Fireside Book in colors, Explains PL ca Swap tadobwaercuauccesaatoeed everything. Act w! Mn s01xeekdbavenwnsaotenc<eceas Marcu, 1930

Faceplate of Novel Design Aids in Lathe Work RDINARY faceplates, because of their large hubs and center holes, often present difficulties where small pieces of work are to be attached to them with the aid of bolts. This is especially true if the CENTRAL SPACE FOR WORK-HOLDING BOLTS

ili!

M1

- | \ 4) \ FACEPLATE HUB OFFSET FROM Bolts can be used BACK OF PLATE as near the center as may be necessary.

bolts which hold the work are to be placed near the center portion. To meet this difficulty, the faceplate illustrated was designed. It has no center hole, and its hub is constructed so as to allow easy access to its central portion, thus facilitating the attachment of bolts and clamps. The pattern used in molding such a faceplate can be simplified if it is split on a center line through the curved sup- ports of the hub.—S. A. AsquiTu. Wooden Covers Protect Ways on Idle Planer ANERS are sometimes idle for long periods of time, thus leaving the ways exposed to the dust and grit of the shop, which becomes ground in when the ma- chine is started. One shop protects the planer ways by providing a board cover for each side. These covers have two V-blocks, one at each end, which fit into the ways. The length of the top board is the same as the exposed portion of the ways when the platen is flush with one end of the bed. These cover boards are put in place over the week-ends or when the machine is to be out of use for any great length of time.—H. L. WHEELER. PLANER WAYS

The wooden covers have V-shaped blocks that fit into the exposed ways of the planer. PirPE leaks may be temporarily repaired by cutting a piece about 214 in. long from an ordinary hose, slitting it down the center, and slipping it over the pipe. Fasten it in place over the leak with an ordinary C-clamp.

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

Makc! Th po sta me

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Marcu, 1930 POPULAR SCIENCE MONTHLY 119 ‘ a TONS ea Mit aes Mera APH a REP aad Thats the Rule I want The, FARRAND RAPID RULE THE ORIGINAL RIGID-FLEXIBLE-CONCAVE RULE The most remarkable practical invention in years. Six or eight-foot steel rules are coiled in vest- pocket sized holder, and with pressure on brakes will shoot out rapidly and rigid as a rod. In- stantly available for measuring straight or curved surfaces, or around bends. Made of finest steel in the world, will last for years. Can be entirely removed from holder and used for end-to-end measurement. Model A Model B Model C Nickeled holder, 8 ft. rule Machined brass holder, 6 ft. rule eee holder of simplified esign, 6 ft. rule Complete $5.00 Complete $3.75 Complete $3.00 YOUR HARDWARE DEALER WILL GLADLY DEMONSTRATE Write to factory for six-inch sample Manufactured by HIRAM A. FARRAND, Inc. BERLIN, N. H. = a a ae a —— I PE I SEE Eq TaN hie PCTS | 7 ' ; ; |

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; : f t : : ' a 120 POPULAR SCIENCE MONTHLY WE a FREIGST Let My Factory Save Tire You $300 to $1000 Price includes all highest quality lum- ber cut to fit, doors, windows, stairs, interior woodwork, lath, shingles, hardware, glass, paints, nails, etc., complete. Plans FREE. Materials fully guaranteed. Monthly payments if desired. Freight paid east of Mississippi River and north of Mason-Dixon line, also to Minnesota, Iowa, Missouri. BUY AT WHOLESALE! Get all materials direct from mill. Many save $300 to $1,0000n their homes. Mill-cut wet, * C EXTRA lumber saves you 40% labor, 30% on ma- CHARGES terials. me portable. Sturdy, agg ee ae Handsome Big Book of Homes manent homes. 34 years’ square dealing a = behind Liberty guarantee. Amazing new 2 — notogra se. . Practical—Beautiful! Mail coupon Today Liberty Homes, Lewis Mf. Co., Dept. 13-C, Bay City, Mi Please send me your 1930 book of Liberty memes, also complete details of your plan, FREE. wy mee materials 5 days on your own t before you pay! **Saved $800 to $1,200 on Lumber”’ says O. P, aie “and the material was ¢ e buying from you,” writes B. A Nebraska ... Mr. Davis saved “between | $1t,000 and $1,500” on his home ... Spellman says “I saved $see by buying from q you.” You can do as well. Every = owner \ ON os hase, kupedn needa eeeae who built a Liberty — eee Write for \ ° , complete information and F INS: . « «:asicin Rica ae ea ee eee LIBERTY OMES Lewis MFG. CO. Dept. 13-C, Bay City, Mich. ae ia a oe es 231 Andy Sannella MILES Talks to Reed Players. Marcu, 1930 AN HOUR! Most sensational toy in years! Exact copy of the fastest ne eee $3. car in the world—Maijor eater s “Golden Arrow.’ Lifelike in ed detail. Beautiful golden-bronze ish like ori . Hidden wheels. eal Dunlop rub- ber tires. Built all of steel. Equipped with racing speed clock-steel motor. Fastest toy on wheels. 21 in. long. $3. (West of Miss. =. 30.) Also Sunbeam and Blue Bird Racers, $3. each. If your dealer can- not supply you, send your order to us. KINGSBURY MFG. CO. 107C Myrtle St., Keene, N. H. Send 10c for a Kingsbury Disc Wheel, Balloon Tire Eraser. KI NGSBURY der TOYS Get this Free Book! On the air tonight, and every night, Andy Sanneila is earning a fabulous with his Selmer Sax. In his book of ‘*Advice to Saxophone Players,’’ he gives more uable information than in ten private lessons. This book also contains Talks to Clarinetists by Alexandre ™m> Selmer. Send for free copy. Ifyou will mention the instru- ™ ment you play, we will send also, samples of our : ner a SELMER B eu tint et INDIANA (In Canada: 516 Yonge St., Toronto» ZIP-ZIP SHOOTER (OUSANDS of boys are happy with this wonderful Zip Zip shooter, in ly and practically ne. au you like hunting and outdoor ve brand to us > or three f 1. Ds, in oF money AUTOMATIC RUBBER CO. ° Columbia, S$. C. # KA th FORMS TO CAST LEAD ee mapenees,, TRAPPE! asters, ee and Farm 4 rful ‘“True to ire? mode Easy and inexpensive a2 w furnish all necessary material. Send 5c Stamp for Mustrated Catalogu Henry C. Schiercke, 1034-72nd St., Brooklyn, N. Y. eer ae el Have a Business of Your Own — Turn Spare Time Into MONEY —=:, . arage workshop. We receive hundreds of oo ling of big money earned. Income will easily meet monthly payments. Read what others have Pm G. W. Fountain, "Rocky Mount, N. C., start- ing with one B-C Machine, working part time in rear of grocery use grew in3 years to occupy a acre of land in new building 50’ x 70’. There e no “hard times’’ where there is a Boice-Crane shop. Table 10x12 in. tilts 45 deg. Cuts 4% in. deep. Bronze —. Sturdy in. Elevates for dadoing. At- deg. Stroke 1% in. both ways. Bronze bear- Ho vey ll na tachments for dadoing, joint- pont » - Vy frame, oe we gene | aes ing, disc and drum sanding, . P. M. sizes of arm. Safety guar . 4 boring, planing, grinding. $30. Dlades. $12. 6 in. Handi-Jointer $75. Joseph | Broemmers, fae ity vd ught a j W. H. Duer, Marquette, Bows. Lathae 4 fnsand 6 int Solnpere Lets tall vou hoe ie tree Machine and '%-b. p. Mich., though in poor health hours into money. Catalog free if you send name of your hardware or Motor for home ee. In sup) rofpped Da of ne 4 in machinery dealer 2 years } A. cupying equip basement shop, two story brick 40’ earning as high as $25.00 a day. W. ae Dept- P.S.3F Now after 4 years needs Original investment $75.00. B. & E. BOICE Toledo, Ohio more room. 4’ Handi-Jointer J , ’ Universal. Table 15x17 in Tables 20 in. Planes % x tilt 45 deg. 8 in. saw cuts 2 = -pabje 8 in. dia. Tits 45 4 in. Fence tilts 45 deg. Jig Saw Combination Electric Wall Fittings What is a three-gang switch and how is it installed? ANG switches can be obtained in sets of two or three switches and in either three single-pole, one single-pole and one Three-gang plates can be obtained that will fit into a single-space wall box. three way, or two single-pole and one _ three way sets. These units take up the same space as one ordinary switch and therefore are handy for installations where old switch boxes are to be used, since no new hole need be cut in the plaster. The cable is run from the new necro’ ‘LINE CONNECTION Sketch of the three-gang switch and diagram of connections necessary for an installation. light outlets right to the old box, the line and fixture connections are made, and the plate is put in place. Is there any wall device that will indi- cate when a fixture is in use? The combination pilot light and switch, shown at the top of page 122, is a convenient means of telling when the cellar light is in use. The plate can be obtained in the single or double size for use in either a single or double wall box. By installing this wall plate at the top of the cellar steps, you can tell at a glance whether you have left the light on or not. The wiring is shown in the illustration and requires few additional connections. Can a wall plate be obtained that com- bines a pilot light and receptacle? Yes, and it is not only a genuine con- venience, but also a protection against accident in the use of heating appliances. ee ee © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. MarcH, 19

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Marcu, 1930 POPULAR SCIENCE MONTHLY FILES will do alot for YOU And they will do the most that any file can do for you if they are stamped with the Nicholeon Brand. The teeth of the Nicholson Flat File are gene | designed to Sharpening a saw takes a remove stock rapidly. There are times when only little practice but it can be . a Nicholson Square File readily done with a Nich- will do. Filing keyways olson Slim Taper File. and slots for example. ' i ‘HERE are any num- ber of uses for files and Nicholson Files for all of them. “File Fil- osophy,” a specially prepared booklet on the subjects of files and filing, willbe sentto you free on request. Drop us a card or tear off the bottom of this page and mail it. We sug- gest that you attend Curved surfaces are not to it now. Wills ineisth weoted hard to get at — with the ening mill saws, the Nich- Nicholson Half Round File. ° olson Mill File does a first rate finishing job. > Se t © Osa NICHOLSON FILE COMPANY Providence, R.1., U.S.A. e25 _—A File for Every Purpose NICHOLSON FILE COMPANY Name Providence, R. I. Gentlemen : Street Address I should be glad to receive a copy of “‘File Filosophy.” There is, of course, no obligation on my part. City State © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. - Sa nea te oR sate ana pane so - pana Pe : Ss aad 5 ’ Se Pa a RN NR GRE SOON TIES: GSI TTI AE REEMER LLIN TRE A Bee} 2 Re AT RT Ce. eet sy

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122 POPULAR SCIENCE MONTHLY Marcu, 1939 § anc, 193¢ NEW MODEL > SOUTH BEND and LATHES LINE TO CELLAR fa FOR THE 7 Manufacturing Plant Service Station : TOGGLE SWITCH Tool Room Electric Shop (SINGLE-POLE) ‘ General Repair Shop _ Engineering Shop Machine Shop and Laboratory SWITCH AND PILOT (2-GANG) All on Easy Payments . We shi Ss h y d hei > The two types of switch and pilot light com- We ship any out Bend Lathe immedi- binations for use in single or double wall boxes. ( y ately upon receipt of only 20 per cent of Catalog price. Balance in 12 equal ,$ The lamp tells when the current is on and | monthly payments. Write for Time thus when the appliance is in usé, elimi- | rh ag Payment Catalog. © nating any possibility of burning out the | | 9-in.x 3-ft.J unior Back element through overheating. The com- Geared Scr “h ee - wee Foes . i shoul wm aiess 3 | bination can be installed easily, a screw Panta 0-08 "sa, . ee 5 renee f8 Veen oe driver being the only tool needed to make and Equipment 169 Motor "car Lathes Sean Ra y the change, as the unit fits into any ard Change Gear Lathes, Ny already existing single-size wall box. | Prices of Popular Sizes of Quick Change Gear 523) amines 2 A porcelain combination switch, pilot Lathes with Equipment Drum Vathes and? 6° 4>; Paes | light, and plug can be obtained for use in Size of Lathe renee... Countershale. = Sent erin mM, ‘Segoe Fone the cellar laundry. A few screws and a ~. wari scone eis ree a little additional wiring are all that is Aes A 490° tbe. $294.60 $398.00 MSP ete a a: hal W F ‘ ; Bese o7ae tee. rte rH e+} KORE ee og necessary for its installation. This device ba 15” x6" 1550 Ibs. 543 720.00 SI PAS Pe ae flor x8 2055 Ibs. 638.00 817.00 ws ad . ee 3 OT LAMP ' WRITE FOR FREE CATALOG WD-o'y ae a. , UA cits IN HERE . __ SOUTH BEND LATHE WORKS eee oe a 232 E. Madisen Street, South Bend, Indiana,U.S.A. ee Pos yy oo °° CORD PLUG j Lathe Builders for 23 years—44,000 users fC IN HERE Famed For Build a Ship Model at Home NE en | t | P erformance! It isa PAs ae ont oe beautiful deco- * ration for your mantel, radio cabinet or it may be Flush and surface types of pilot and receptacle used in any part of the hom combinations. The surface type has a switch. U. S. Pats 1593658. * 1034103-04 feta sien Se, 25 nebo hn La Pinta, size, 26 inches h a 11 | | fits on a standard two-gang switch box Mayflower’ size. 26, inenes hen, of the surface type, making it suitable for nehes wide, nehes 10) } Consticution, size, 25 inches beh, the general surface wiring found in cellars, nehes 2. nehes 10) 4 s Flying Cloud, size. 27 inches high, Can a wall plate combination be ob- 9 inches wide, '36 inches lon i 7 i i Susans tsetse Weeene. tained that ‘includes a switch, pilot, ELECTRAD TONATROLS give smooth, quiet adjustment of radio volume. Wear resist- ing construction gives longer life and greater accuracy of setting. Types for every receiver, including filament plus a few cents pos and receptacle? switch, $1.50 to $3.00. These models are 2 sold i in knock down form. All ~ ° . Also Super-TONATROL for high powered parte are cut to fit and ready to assemble. They Three single units placed under a single receivers. Extra long-lived and amazingly Money pee Mn peng Sa a” = a wall plate form this combination (see the smooth. $2.40 to $3.50. = ec accompany all fore P - Write Dept. P.S.3 for details. M NIA for free illustrated catalog. last illustration). A box large enough can 175 Varick St. New York, N-Y pept. MINIATURE SHIP MODELS, INC. || be set in the wall by enlarging the hole made for a single wall plate. The recep- tacle has a protecting cover which fits flush with the plate when the plug is not stew YOU Can asso in use. This is shown below. We furtuh inerucions, sunt Rotts. | Can the quantity of heat given off by $1.65 up; oth ith ch i] \. ; 4} ? fate oe ee on OES | o Ree appliance be regulated: ELECTRAD CAMPBELL’S INFRA; we) BY. ¢ details, prices \aria "Writs {athers Clocks, Writer seecal Bee | _ For those who wish to control the heat AnERecan CHIME clock ‘COMPANY given off by a heating appliance, a heat 1691-T Ruftner St control plug can be purchased. This plug has a disk which can be adjusted to reg- The PERFECT SHAVE ulate accurately the amount of current Is HERE! allowed to flow through the element. The Have You plug fits the standard appliance and can Some 3 s hard to ntieme tt 3 s trie. fatenen has ~ be readily attached to the existing cord. e age old problem of shaving. Just as surely as Troublesome the safety razor took the place of the straight razor —Haroip P. STRAND. Allment ? so has the Hollow Grinder made all stroppers obso- - Infra-Red Rays relieve co tien or tre bles causing lete. ches and pales in the ongeat ion o Campbell I a Think of it—the Bello Hollow Grinder grinds two a new concave edges on any Gillette-ty lade. And ned Rey co cad part al the beady. beam of Infra it’s with the concave edge that you pation real shaving RECEPTACLE These rays penetrate deeply into the tissues. As comfort. they penstoate ey create — active circulation ~! the Free Trial Offer ost ailments are toc t —re - congestion and you odlleve fey Nature If you want a super-keen edge on your blade each herself does the healing by active, normal blood cir- morning—get a Bello Hollow Grinder. Try one for poe nr og , ten days at our expense. Mail the coupon now—and Why Su fler Nee oo Pain? =i "ll send Ln Bello. pam. —_ a —_ bank or usiness reference and we'll include a free razor Ma you or oqme friend have a troublesome ailment, a cloth to save the family towels. amp like this is a blessing. May be used safely by anyone. BELL peered Tell Us Your Trouble ansicigipaaaeitnaatand ates es Get Our Book on Infra-Red Rays | Bits cor, pent. p.$.,,Gardoer, Mase Quotes leadi ng authorities as well as users or mail $3.75 in full payment. Also cond thes sanee cloth. Teen | | Ee ST LE Infra-Red Rays have brought wonderful results for or local business reference. PLOT ated ¥ isan, wk + us “y you their letters. Write today for MN ash dbacedatclacsieas sasatanossacwitovccssesecuscuius eon oie ) ans RECEPTACLE. our giving details. BD bas itn ctnbsadsxcceunbineedendbaieenscatevekenendnn ee The WILLIAM CAMPBELLCOMPANY | cw... CR EA: A threo-gang combination with push buttos switch, pilot light, and safety cover receptacle. Dept. 1041 Alliance, Ohio Cicheck here for 4 money-making plans for agents. © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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MaRcH, 1930 POPULAR SCIENCE MONTHLY 123 Tough... .with a good temper ICK a stubborn screw and see what happens when you “lean on” this Stanley “One Hundred Plus” Screw Driver. You can easily understand why this screw driver will stand the rough use and abuse of heavy work when you read below how it is made. Here are some of the reasons why craftsmen and mechanics select the “One Hundred Plus” Screw Driver. 1. Tough Hickory Handle. Capped with leather washers, it has the same con- struction as used in a socket chisel to withstand pounding. Comfortable fluted grip. + 2. One piece forged steel blade tempered its entire length. Blade will withstand severe prying and twisting strains without bending or breaking. bs 3. Tang has two heavy wings forged its entire length which lock the blade against turning. 4. Tips will not chip. Equal flatness on Ask your both sides reduces the tendency to turn out of screw slot. hardware dealer suis . 3, 4. 5, 6,8, 10 ade in seven sizes — 3, 4, 5, 6, 8, to show you and 12 inch blades. this screw driver THE STANLEY RULE & LEVEL PLANT New Britain, Conn. STANLEY TOOLS ‘The Choice of the Trades” © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. ~~ nomen e i ca SPS eae =F a a a ee ree ee Ee ng Rape ee eran aber iy nla Tinie Lal en me PAS Rn Reh tein Po

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124 POPULAR SCIENCE MONTHLY Marca, 1939 How to Truss-Wind a Bait Rod Special Silk Thread Wrapping Adds to Strength and Resiliency of a Homemade Rod for Casting By ROBERT PAGE LINCOLN rod with silk threads is probably the most ingenious manner of rod wind- ing open to the amateur rod maker. It isa method that not only strengthens the rod greatly but also gives it a graceful, resilient action. Solid wood tips so wound have double or triple the value of like tips wound straight across in the ordinary manner. Two-piece rods of the truss- wound variety are considered by many fishermen to be ideal for use in bait casting for bass. Obviously the ferrule or jointing place in this rod should not be in the middle, or too great a strain will fall upon it at that point. Rather have the tip 40 in. in length and the butt piece 26 in., the whole rod being 5 ft. 6 in. over all. If desired, the bamboo butt section can be purchased complete for ap- proximately $5. The rod tips can be made of betha- bara, lancewood, greenheart, dagama, and many other woods, which can be ob- tained through any of the larger sporting goods supply companies. In every in- 3 1 Ys am} stone Ps. thes. Q4 2) CROSS WINDING (EIGHT CROSSED THREADS) (SRSA NAIL IN STra winding or truss-winding a SOLID WINDING REEL SEAT cui Ath, ‘ WN Ula Messi = ; * E ARAN ie in = ARM t my A | | J stance only the very highest quality of wood should be selected, free from knots, slivers, and other inequalities of grain. The taper of the rod is obtained, as shown in the illustration at the bottom of the page, by supplying the dimensions at stations 10 in. apart. The butt piece is 154 in. in diameter over its whole length. The hand grasp and grip are made up of cork washers (untrimmed), which can be purchased from any firm that supplies rod making materials. These washers are liberally coated with rod maker’s cement both on the inside and in between the corks and are then slipped on the butt section. A wood sleeve, or filler, which can also be purchased for a few cents, is then driven up close to the cork, after which the reel seat is forced home over that. Then the corks for the forward grip are cemented in place, the cork adjacent to the end of the reel seat being carefully trimmed to fit snug. The tip end of the cork forward grip is then shaped and the winding check or taper is forced in place. Trim the washers to the required shape by means of a file and various grades of sandpaper. For less than a dollar, one may obtain both the cork hand grasp and the cork forward grip ready to slip on without any further trouble save applying cement to the wood they are placed on. Solid wood for rods comes in %-in, stock and has to be planed down. Cut the stick a little longer than the 40 in. for the tip piece and bore two holes near the end of it, preferably in the end that is to be the heaviest. Drive a nail into the workbench and catch the stick by placing the hole over this nail; this will be a distinct aid in planing. As you turn the piece, shift from one hole to the other. In planing use a very sharp block plane set to cut fine. Do not plane more than two strokes on an edge before turning it, and as you get down fine use your calipers often to see that the diameter at various points compares favorably with the di- mensions as given. Ferrules for a rod with one jointing place should be of the capped and welted variety, "44, in. in diameter. There are, - of course, two ferrules, male and female. Two agate guides, size 2 and 3, raised, are needed, also an agate, offset, tip-top guide, and butt-cap. In winding a rod start about an inch from the winding check or taper on the rod, just ahead of the forward grip. Eight threads are used in winding the length, two threads meeting in a V (as shown), the distance between each V being % in. To start, catch in a thread as shown and start winding. The distance from where FERRULE (FEMALE) ‘ ae BSS OOO SSShSe m7) co ) BUTT WS BUTT PARTLY /N SECTION oy WASHERS we SLEEVE = PIECE taper CROSS WINDING we 2'- ” AN : — 4 oo SOLID WINDING SOLID WINDING, | 2 Ss cee =e BUTT COMPLETED HAND GRASP- REEL SEAT A FORWARD GRIP {= tN GUIDES STIRRUP TOP —~—~__ = am We eee | @:0:0:0:0::4) 10" 10" 10" 10" FERRULE (MALE) “si 3-4 oS NS 7/P-(PARTLY IN SECTION) Dimensions of the two-piece casting rod. How the eight silk threads are wrapped and how the taper is planed with the aid of a nail driven into the bench. Note the wood sleeve over which the metal reel seat is placed.

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Marcu, 1930 POPULAR SCIENCE MONTHLY 125 Drop Forged---Not Knowing the inside story of the tools you use is interesting, but not as import- ant as knowing the outward results of those inside facts. It is a fact that TRIMO handles could be more easily made of cast iron. It is a more important fact that those han- dles could be more easily broken if they were. Drop forging the handle is simply one of the many inside facts of the famous TRIMO pipe wrench. No pipe wrench made can give you more ser- vice, strength, and safety than TRIMO. No pains are spared to give you the finest tool obtainable in this All-Steel pipe wrench. The jaws are replaceable. Nut guards keep the adjustment true. YOUR HARDWARE DEALER WILL FILL YOUR ORDER FOR TRIMO—and approve your choice. rw FRIMO . Pipe Wrench All Steel for Strength and Safety Made by Trimont Mfe. Co., Inc., Roxbury (Boston), Mass. © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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126 a a ON THIS td s e-F CREWORIVER—of tompored crucinis oleae ories tke fone where, ors wane aie x f @ Cine seve ee eee nen “ : arsenite, 17: ve 7 Proposition! E @ Pst, 4808 N. Ashiand Ave., CHICAGO, ILL. PTT ITI IAI Also FREE siving amazing 125-Picture story of The “Pocket Machine Shop!” Off they come! EIFEL-FLASH, PUERENCH KIT “Eye-fel-Fiash’’) *‘The T. N. T. of Tools” Ai1-Second of Gear-Jaws you 3, Bends. 24 oz. Master KIT. —for Lo ofa tool. DO $50.00, andmany things no other toolscandol A GUARANTEED Suser-Quality Gripping Machine that Pays for itsalf in the 4-Weeks’ Trial Half Million in Use ’round the World—Thousands etc.—“horse-&- For the Hoine.Workshop, or Manual Training WEE this 500 Ib. capacity implex Jack, you can straighten window or door glued work, radio cabinets, stretch shoes, etc. Thislittle “Jack in the Box’’ is for the man who uses tools, or the boy _inter- ested in manual train- ing or mechanical toys, Btardily built beesditenty finished, dily t, beautifully and un- conditionally guaranteed. Its exclusive safety feature of the visible screw and power of the fiarger Simplex Jacks, and will be sent you prepaid for 35 cents—Canada 45 cents. Money refunded without question and instantly if not satisfied. urpose is to demoastrate and advertise the Ask your Merdpore dealer for the larger implex Jacks POPULAR SCIENCE MONTHLY Marca, 1939 you start to where your thread first crosses a point directly above it is 1% in. This distance may be lessened gradually to an inch at the tip section. Have your rod jointed up and as the rod is turned wind right over the ferrules, as the cross windings are made latér and the truss windings across the ferrules trimmed off. In spiral winding it is of the utmost importance that the thread be kept taut from the beginning to the end. AVING wound your first thread to the very tip, secure it thoroughly by a cross winding so that it will not slip. Next thread No. 2 is fastened at the bot- tom; whereas thread No. 1 was wrapped toward the left, this second thread winds to the right. This also is carried to the tip and securely fastened. Thread No. 3 is now caught in % in. to the right of the V of the first two threads and is wound to the left. The fourth thread is caught in on the left side and is carried to the right. Keep on alternating from right to left until eight threads are carried to the tip of the rod, after which solid cross wind- ings at the bottom of the ferrules and at the tip can be put in place. Start your solid windings in each instance at least X% in. up on the truss windings as shown. Do the same at the ferrule places, but do not cut the truss threads where they cross the ferrules before both windings are in place. A solid winding both above and below the male and female ferrule of no less than an inch should be made, likewise at the tip of the rod, as it is neces- sary that the truss threads be held very firmly in place. When your solid windings are com- pleted your guides can be laid on. It is a good idea to spread a little varnish where the guides are to be and set the guides in this and let them harden into place, then wind the thread around each end. By applying the varnish underneath, the moisture has no chance to get at the truss threads. Apply your varnish of the rod making sort heated to a lukewarm state and work in a warm room free from dust. Go over the rod thoroughly and then hang up to dry. Three weeks is not too long for the first coat to dry, when successive coats can be applied till the diamond squares between the truss threads are more or less filled up. Under no circumstances bend the rod till you have completed the last varnish- ing. Three coats are sufficient but more can be applied as occasion demands, especially after each fishing season. Regluing Loose Joints HEN only a joint or two is loose in a piece of furniture, it is usually possible to spring the parts far enough apart to insert glue and then bind them together or clamp them until the glue has hardened. If possible scrape off the old glue before applying new glue. Vinegar applied vigorously with an old toothbrush often will remove the old glue. If the joint is very loose, use plastic wood cement instead of glue, as glue itself will not hold a loose joint. Remove the surplus glue or cement with a cloth moistened with warm water. How to Rejuvenate Old Oil Paintings IL paintings that have been hanging! for a number of years sometimes be. come dull and lifeless. Such paintings cag’ be quickly brought back to their former” clearness by cleaning and then brushing! with a special picture varnish. a In cleaning, care must be taken. Use lukewarm water and only the best soaps,” Dip a lintless rag into the soapy water and# carefully wipe off all the dust and dirt.) The picture should then be allowed to dry thoroughly. . One of the best varnishes for doing this sort of work consists of sandarac gum, denatured alcohol, and ozonized turpen- tine. To prepare such a varnish, place the’ sandarac gum —an ounce will be more 7 _ ae a RO i te i vitor 6 ‘ The varnish is applied with a soft brush and is spread over the entire oil painting. 4 than enough for all ordinary purposes—in an 8-oz. bottle. Fill the bottle three quar- ters full of alcohol and then add about two teaspoons of ozonized turpentine. Or- dinary turpentine cannot be used since it | is insoluble in alcohol. Shake the bottle and keep it in a warm—not hot—place until most or all of the gum has dissolved. This varnish is applied by means of a soft brush and is spread thoroughly over the entire painting. If one application of the varnish is not enough to give it a high gloss, a second and even a third coat may be necessary. .- If these steps are carried out with care and patience, even the best painting will not be harmed by this method of ren-} ovation. This special picture varnish can also be } used for retouching scratches on the sur- } faces of furniture —H. Bape. Grinding Soft Rubber HOSE who have tried it know that while hard rubber can be ground to shape on an ordinary emery wheel, it is practically impossible to shape soft rub- ber in the same manner. This difficulty can be overcome by using an emery wheel having square teeth cut into its surface. These teeth should be 34 in. wide and should have a pitch of 11%4 in.—H. W. Swope. To REMOVE old putty from window frames, use a chisel about 1 in. wide. In- cidentally, a chisel of this size is a good one to keep on hand for general work. Care must be exercised not to allow the chisel to cut into the wood. If the putty is set very tight, there is danger that pieces of wood will come off with the putty. % © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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Marcy, 1930 POPULAR SCIENCE MONTHLY 127 VV On A complete “& electric workshop for home or business VERY man who hasa workbench The Workace Electric Woodworker has often wished for a com- —a complete all-electric shop — plete oucfit of power driven wood- costs but $9.00 first payment and working machinery. Such a work- $9.00 a month. This includes power shop is now as easy to possess as a_ driven tools for every woodworking radio set, and costs much less. operation. Low Price *8QO EasyTerms Here’s a hobby that gives you relaxation from everyday cares —bringing pleasure and profit. this: Thousands of men and boys 4° Planer set up and use right away. The See ee Eee eee i Siaeten onting cramtnction Setamainetar h 2 bby. ake hundreds o 6° x 36” Lathe one of your local hardware stores things with the Workace Elec- 8° Disc Sander so that you will know the man tric Woodworker. Under the 6’ Buffing Wheel you are dealing with and get his & i F Tlecn Jig Saw Attachment for the Workace Electric $10 Woodworker...........- ineludes all A down payment of $9.00 brings you the complete Workace All- Electric Woodworker ready to magic of the whirring saw, 5°E Grind pr nl lathe, sande - drill, \? Drill Chuck service and cooperation. grinder and buffing wheel (all \% H. P. G. E. Motor, The Wallace Guarantee assures can tnaiated in ae Gees be A. C., 60 replacement of defective parts. Woodworker) raw lumber is easily converted into furniture, household necessities and Large reproduction For every coupon mailed in we countless other articles. Work with separable Plug. will send a large picture of the accucstes sceneateal ne °$75 out your own ideas with your || 7>¢PianerandCircu- if entire outfit and a complete de- own complete electric workshop. plete unitsand may be |j scription of each item. There’s no better gift for the grow- pogo ey 4 Send for full particulars and ing boy than Workace. It provides low priceof $25.00 each. we will refer you to our dealer a wholesome man-building outlet for his energy and enthusiasm. who is nearest to you. MAIL THE COUPON TODAY J. D. WALLACE & COMPANY, Wilcox St. at California Ave., Chicago ‘1 West 42nd Street, New York City 268 Market Street, San Francisco Please send me large size photograph and particulars about the Workace Electric Woodworker. Also interested in [] Jig Saw— 0 Band Saw — (J Radial Saw — () Shaper — [ Planer. © Yoctaee ortable Fiee= ewe Firm Workace Rad al Saw, COST SESH SESE SEES SHES HE SESH HE SESH SESE SH SESE SESH SESE EH SESE SEES sets at any angle $14 0 Address. Cast Iron Table $10 fate Cast Iron Legs $15 Extra © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. .

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128 Unsightly eracks... Easily resurfaced . % ‘ oe F} 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 absolute whiteness and permanence. At paint, wall-paper and hard- ware stores. Rutland Fire Clay Co., Rutland, Vermont. RUTLAND PATCHING PLASTER Seep euepeeepeaeeeeeupeaeeeeoeeseeaeaeeaes Se ee ee PARKS WOODWORKING MACHINES Guaranteed ten years Cabinet Shop Special No. 10 $290 with Motor You ought to have this handy Parks in your shop. Compact, complete machine de &@ signed like a big production outfit at 1/5 the cost. Floor space required only 42x72 inches. Does any kind of cabinet or joinery work. Write for circular. The Parks Woodworking Machine Co. .» Cincinnati, Oh 1547 Knowlton St |, Ohio Canadian Factory: 338 Notre Dame East, Montreal BURN YOUR NAME ON TOOLS Tools FromTheft. write with elec- tricity any name or on the hard- est POPULAR SCIENCE MONTHLY Marcu, 1939 mounting. cluding the great ringed nebula in Lyra and the belts and red spot on Jupiter. The pedestal consists of a 6-in. di- ameter nipple, 30 in. long, having a cap on the upper end and a standard 6-in. flange on the lower end. The flange is securely bolted to a foundation of concrete, and a 2 by 2 in. two-strap pipe saddle is welded to the cap to provide a fastening for the 2-in. pipe- bend return which is 12 in. from cen- ter to center. On both ends of this return bend are attached two 2-in. extra heavy tees. The threads on the run of these tees have been milled out smooth to receive the polar axis, which consists of a Ford rear axle housing, including the shaft, roller bearings, brake drum, and brake shoe. The differential housing, however, is not used. On the hub of the model-T Ford axle is welded another 2-in. tee with Uessidial Pipe Mount for Telescope Pipes and standard pipe fittings were used in construct- ing this unique, easily adjusted telescope mounting. ROBABLY few readers have ever Possciste gas pipe and astronomical research in the same channels of their minds. These have been associated, however, and out of this thought has grown an efficient and durable telescope The mounting illustrated was made by the writer and is now in use on the grounds of his home in Dallas, Texas. The telescope is the largest in the ex- treme southern part of the United States. Many distant stars and planets have been clearly seen and photographed, in- es Homemade Pedestal Built Entirely of Standard Fittings and Two Auto Axles By C. A. Howarp the threaded portion milled-out smooth, The declination axis is made from an- other Ford axle. On the lower end of this axis is welded a 2-in. floor flange to receive the counterbalance, which is a 10-in. dresser type coupling faced on each end with %-in. metal disks and filled with lead to offset the weight of the telescope tube, Pressure is applied to the brake drums by operating the emergency brake rods. The rods are threaded on the end and wheels from two 4-in. gate valves are tapped and attached. Between the drums and the wheels are placed pieces of 3%-in. pipe. As the wheels are turned in the tightening direction, they bear against these short sec- tions of pipe and pull the brake rods, thus applying the pressure. Inside, at the lower end of the telescope tube, which is made from 16-gage galvanized iron, is placed the mirror. The mirror shell has a l-in. angle iron flange riveted on its outer edge. The end of the telescope tube has a similar flange supplied with holes for the attachment of the speculum shell. On the back of this speculum shell are the adjusting screws which enable the cone of light to be trained on the prism suspended at the other end of the tele- scope tube. For the remainder of the in- strument, regular optical astronomical equipment is used. At the present time, the writer and Dr. A. D. Laugenour, his coworker and incidentally the codesigner of this tele- scope mounting, are hard at work study- ing the craters in the moon. and the two men who designed it, Mr. The telescope Howard (left) and Dr. Laugenour, his coworker. © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. Magch, 193¢ . Ju F YO use S For fillit surfaces, there’s r so easy | one job hesion. | through with a- Filler w used it ¢ No wor Savogre never b To m quarte Savor Send tory | Nam Addr

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» 1939 v€ She SESE — eS CD @o vr SS .6U Sh MagcH, 1930 POPULAR SCIENCE MONTHLY 129 Just What You’ve Been Waiting For! A Crack Filler that WON’T SHRINK F YOU want to make repairs that stay put, use Savogran Crack Filler. For filling cracks and holes, building up wood surfaces, and all sorts of general repair work, there’s nothing like it. Savogran Crack Filler is so easy to work with that when you've finished one job you look for the next. It has great ad- hesion. It takes paint perfectly—does not show through like a puttied hole even when finished with a stain. And best of all, Savogran Crack Filler won’t shrink. The places where you have used it defy detection. No work-bench is complete without a can of Savogran Crack Filler. Try it once and you will never be without it. Note the price of this superior SAVOGRAN filler and send for our introductory can right away if a near-by paint or hardware store cannot supply you. Savogran Crack Filler is a product of the Savogran Company, India Wharf, Boston, Mass., makers of the famous Painters’ Savogran. Painters’ Savogran has been used by painters and householders for more than 35 years because it saves them time and money. Painters’ Savogran softens the hardest paint-brush and makes it usable again, cleans dirt and grease like magic before repainting, removes paint and varnish, strips off ground-in dirt without scrubbing. If you do any painting—get acquainted with Painters’ Savogran. CRACK FILLER PATENT APPLIED FOR Big One-Pound Can A pounp of Savogran Crack Filler costs you only 30 cents. For painters, woodworkers, industrials, and other large users, Savogran Crack Filler is sup- plied in 5-lb.' cans ($1.25) and 35-lb. all-metal pails ($7.70). Low price—no hardening in the can— no waste—here is the biggest value on the market. Special Offer To make new friends everywhere for this popular filler we will send you a quarter-pound can of Savogran Crack Filler on receipt of 10 cents. Use coupon. Only 30 CENTS . (coupon) Savocran Company, India Wharf, Boston, Mass., Dept. S3 Send me a 4-Ib. can of Savogran Crack Filler at your Special Introduc- tory Price. I enclose 10 cents. Name Address... Famous Ring Test Proves Non-Shrinking Savogran Competitive Crack Filler Material 4. Two steel rings were filled and allowed to dry. Here are the unretouched photographs showing what happened. Abore—Rings at the end of first day. Savogran Crack Filler tight as a drum. “X”—considerableJshrink- age away from ring. Here are photographs taken at end of three days. Above—“X” so badly shrunk that it drops out of the ring completely. Below—Savogran Crack Filler tight as ever. Mirror photograph shows great pressure being applied without dislodging or mov- ing the filler. SavogranCrack Filler stays put! . Make this sensational test yourself!

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130 POPULAR SCIENCE MONTHLY Here’s That Long-Hoped-for Handbook For Your Home Workshop equately a widespread need. It Will Show You How to construction and repair man. With the Expert Help of THE HOME WORKSHOP MANUAL A single-volume encyclopedia of plans and methods of construction and repair giving practical directions for making scores of useful and beautiful things. Just the book you've always wanted. It gives you clear, complete, and simple direc- tions 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 k in your tool chest for quick reference—follow its plans and directions every time you have a job to do with tools—and it will soon make an expert of you. It’s a miné of ideas for making useful things, a whole library of practical plans and usable directions. It offers the most expert guidance, for its material has been prepared by twenty well-known specialists in as Contains 496 many lines of work, and has been approved by the Home Workshop pages and Department of Popular Science Monthly. 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. more than 500 illustrations Never before have so many plans and directions been assembled in one volume. The scope of The Home Workshop Manual is really amazing. It is hard to believe that such a great variety of things to make can be covered in such complete detail until you actually see the book and look through its sixteen big sections. But once you have seen for your- self what a gold mine of ideas it is and have worked out for yourself some of its 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 sixteen sections cover: 1. Building Fine Furniture by Hand 2. Furniture of Modern Design 3. How to Use Small Woodworking Machinery 4. Repairing Old Furniture 5. Toys to Delight the Children 6. Novelties namental and Amus- ing 7. Woodturning Simplified 8. Decorative Metal Work 9. Model Making 10. Radio and Electrical Projects 11. Improvements for House and« arden 12. Boats and Sports 13. Painting and Decorating 14. Woodworking Tools 15. Equipment to Make for Your - Home Shop 16. Better Home Workshop Methods You Will Get One of the First Copies Printed --efor FREE Examination. finest work of its kind ever produced by any publisher, will show you how to make articles of great beauty and value, its price will be only $5.00. No such investment that you have ever made will bring you the pleasure, and satisfaction,and profit that you will secure through your ownership and use of this manual. And you need ; Popular Science Publishin: ' 1 ' ' not pay a penny for it until after you have gone thor- . ' 1 i] J i] ' q Con 381 tourth Avenue, New York, N. Y. Please send me as soon as pepeenes a copy of THE HOME WORKSHOP MA AL for free examina- tion. Within ten days of receipt I may return the volume, if I wish, and owe not ing. If I keep it I will remit $5.00 within ten days which pays in full for the Manual. MAR-30 oughly through its profusely illustrated pages. You need send no money NOW—the manual will come for FREE Examination. And if you decide that you do not need it, simply return it and you owe nothing. Otherwise remit $5.00 and retain the manual. Planned, in response to many requests, under the supervision of The Home Workshop Dept. of Popular Science Monthly to meet ad- Be Your Own furniture builder—electrician— radio expert—painter—decorator—toy maker —model mechanic—garden craftsman—metal worker—boat builder—and general all-around While this big manual, which will truly be the very ™™"™"™"*ORDER ON THIS COUPON**"""™ Marcu, 1939 Reader Builds Dog a Modern Home W dogs can boast of having a resi- dence as fine as the one built by G. 0. Lawrence, of Semaphore, Adelaide, South Australia, and pictured above. Figuratively speaking, the house has all the conveniences of a modern home. As Mr. Lawrence expresses it in his letter, “Our dog is a very happy one, and with a little patience we hope to train him to turn the light on for himself so that on dark nights there will be no danger of his tripping over the doorstep!” ; Bricks and cement form the foundation. The wooden framework is built of 74 by 134 in. stock, the walls are of % by 6 in. tongued and grooved boards, and the window has three lights made from 434 by 6% in. photographic plates. Just outside the door is a small orna- mental bracket lamp with glass windows. It - lighted by means of a two-volt dry cell. The house has proved to be wholly satisfactory. Perhaps the principal reason is that the wooden frame is not attached to the foundation, and the house there- fore can be cleaned and aired easily. ED GALV. IRON ee = f et ae ae OLD PHOTO PLATES BRICKS AND CEMENT —— 2-0 eo Front and side views of frame and also of com- pleted house. Method of bending doorframe. Marcu, | HI _ more | a lon; Mc More becat the f: A able decis Tec zatio the s rapi wher betw 15th pose then had are | plar the ee W our: Ins wit

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, 1939 —_ - =? CO. Te Marcu, 1930 POPULAR SCIENCE MONTHLY 131 The Alexander Hamilton Institute ANNOUNCES | New Executive Training for men who want to be independent in the next five years HE next five years in American busi- yee will offer more opportunity and more danger than any similar period for a long time. More men will achieve independence. More men who might achieve it will fail because of a failure properly to analyze the facts. A right program will be more profit- able than it has ever been. A wrong decision will be far more costly. To put it in other words, the organi- zation of business, the tempo of business, the speed of business are all in process of rapid change. The evidence is every- where. In a brief period of thirty days between October 15th and November 15th, 1929, thousands of men who sup- posed that they were secure for life found themselves suddenly ruined. Thousands had their confidence so shaken that they are dazed and wondering. They have no plan. “‘ What will happen to business in the next few years?” they are asking. “What program should we lay out for ourselves?” The Institute foresaw the trend Two years ago the Alexander Hamilton Institute, from its nation-wide contact with business leaders, sensed the tre- mendous changes which were about to come, and began to make preparations to meet them. The Institute’s original Course and Service in business was a great Course and did a great work. More than 398,000 men made it a part of their business equip- ment, and are far ahead because they did. But the Institute saw that revolu- tionary changes were in prospect. Little business units were being merged into big units. Industries were reaching out into foreign markets. Security prices were about to become subject to,a whole new set of conditions. Production methods were being revolutionized. The sales organi- zation and strategy of the past were entirely unfitted for the new competition. The responsibilities of guiding the new business could not be discharged by men whose training had been in the old. The Institute said: “‘ We must prepare a wholly new Course to meet the new conditions. We must engage the co- operation of authorities whose business success belongs to the present, and not to the past. They must be the biggest and most successful men of the present—the men who will be the leaders during the coming five years.” Without regard to cost, the Institute went out to enlist the co-operation of the nation’s business leaders. The response was even beyond its most sanguine expectations. In effect, these men said: ** The greatest need of all is for trained leadership. Count on us. Any contribu- tion we can make to this New Executive Training will be a contribution to our own best interests, because it will fur- nish us with more of the sort of execu- tives we need.” It is impossible in this page to give detailed facts about the New Course and Service. It is new from start to finish— so new that the latter part will not be entirely off the presses for some months. Every unit will come to you fresh and live and breathing—straight from the very inner sanctums of this new business world. We invite you to send for the full facts in a new book entitled: “What an Executives Should Know.” It is a book- let that should be read by every man who expects to win a secure place for himself in the next five years. It is well worth an hour of your time. And it is free. Send for your copy today. You cannot gain a proper perspective on what lies ahead unless you look at the picture through the eyes of the country’s biggest men. Alexander Hamilton Institute, 221 Astor Place, New York City.(In Canada address Alexander Hamilton Institute, Ltd., C. P. R. Building, Toronto) Please send me “What an Executive Should Know,” which describes the new Modern Business Course and Service. Name Business Business Address__—. Position

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132 | Strongest Adhesive Known In addition to unfailing and lasting adhesive qualities CASCO has many advantages over ready mixed liquid glue or bulk glue. It glues prac- tically everything, wood to wood, metal, glass, cardboard, leather or paper—and glues it permanently. No waste. One pound of the dry powder makes 114 quarts of liquid glue. And it’s all glue—high powered —wide-spreading. No heating. Mix it in cold water and use it cold. No odor. The unpleasant reek of “eooking glue” is gone when you use Casco. It’s clean and convenient to use. Strength: A Casco- lued joint is stronger than the wood itself. Waterproof. Casco Glued means glued permanently to withstand moisture or atmospheric changes. Endorsed. Leading aeroplane and woodworking industries have for years put the seal of their approval on Casco. Convenience. Now Casco is avail- able to you in 1 or 1 lb. packages. Try the 10c sample on your next gluing job. You can glue it better with Casco. Fill out completely the coupon below— one test will convince you that Casco is the most practical, durable, con- renient and inexpensive glue you have ever used. THE CASEIN a COMPANY 15 PARK ROW “NEW YORK PECIALINTRODUCTORY TRIAL OFFER’ The Casein Manufacturing Company of America, Inc. 15 Park Row, New York Enclosed find 10c (stamps only) to cover postage and handling cost for which send me your trial package of Casco Waterproof Glue. rer eT TTT Tere re. ee clude) POPULAR SCIENCE MONTHLY Marcu, 1930 ee Modernistic Radio Cabinet Space is provided in the cabinet for a radio set, loudspeaker, phonograph, and library of records. wishes to build furniture of the newer trend, this combined radio and phonograph cabinet has the merits of novelty and utility. It affords ample room for most types of receiving sets as well as space for a phonograph and records. Painted in well-selected colors, it can be brought into harmony with the existing color scheme of the room in which it is to be placed.: The original cabinet was built to re- ceive an all-electric phonograph with a motor-driven turntable and an electric pick-up. This type of phonograph was chosen for its tonal qualities and because it is possible to regulate the volume to any degree desired. The radio set used by the writer is = a popular priced all-electric set having a long. air- column speaker. YOR the amateur woodworker who battery set with a cone or dynamic speaker, however, If you desire to use a == By RicHArD H. SpPESSARD together. Toadd rigidity, the speaker com- partment is backed solidly with planking. In case a power amplifier is installed, a hinged door with an additional shelf can be provided. The record compartments are first built and then attached to the cabinet with screws started from the inside of the speaker cabinet. When the compartments on both sides have been completed, the molding can be mitered around the bottom. Like the record sections, the phono- graph compartment should be made separately and screwed fast to the main cabinet. The top is hinged in the rear with one long hinge and is provided with a lid catch to support it when open. The doors for the main cabinet each consist of a single-width board. They are hinged and have a friction catch at the top. The grille work in front of the speaker is plain in design to harmonize with the angular scheme of the cabinet. It is made just the size of the door opening and is held in place with screws at the top and bottom. The completed cabinet should be sandpapered and given three coats of paint and later a coat of clear varnish or one coat of undercoater and two of enamel. It is then rubbed lightly with a mixture of FF powdered pumice stone and oil and polished with any good grade of furniture polish. # PHONO- GRAPH 4 RADIO there will be plenty of room for them. A spring-wound motor from a discarded ~* phonograph will work sat- isfactorily in case the build- bg : ae er wishes to cut down on the cost of the outfit. ae c=J | in construction, a light a To keep the cabinet light 4 a wood such as yellow poplar should be used; it has the added advantage of being easy to work and will take paint evenly. The cabinet proper con- 24%: ra a ee A—u% = 39% Ot 19" PJ sists of the radio and MINGES ~ g mili speaker compartments. The — ar | top, sides, shelf, and bot- ia i r tom are made separately of narrow tongued and grooved boards, which are glued Sl 20%" did SECTION A-B Yellow poplar or other easily worked wood is desirable for the construction. The radio section may be modified as necessary. MARCH, | —— Ea H ce that g¢ illustra solutio guessil Belo two pl appeal The either Ss P ing t | order, | the b | right | indicé | that piece: side | Ta 13, 1 Piece 15A that must Ni stain that thes piece tage In size card whi N puz: FE

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Marcu, 1930

Easily Citta Block Puzzles HILE little difficulty should be en- countered in constructing the parts that go to make up the two block puzzles illustrated at the bottom of the page, the solutions are of a type to keep your friends guessing a long time. Below are given the solutions to the two puzzles of a similar character which appeared in P.S.M., Feb. ’30, p. 117. The two new puzzles can be made from either 1% or 34 in. square stock. In shap-

Er] OE RRS

Solutions to the two puzzles which ap- peared in the February issue on page 117. ing the pieces, cut them in numerical order, making all cuts at right angles to the bottom face of the stock and at either right angles or 45 degrees to the sides as indicated. In the cross puzzle be sure that the points on the left-hand side of pieces 7 and 9 are in the center of the side (see illustration). Take particular care in cutting pieces 13, 14, and 15A of the square puzzle. Piece 13 is slightly longer than 7 or 8, and 15A is half the size of 9 or 12. Be sure that piece 15A fits on piece 15, as these must be glued together. Number all of the pieces as shown and stain each puzzle set a different color so that they can be easily identified. Since these puzzles are solved with all of the pieces right side up, it will be an advan- tage to stain only one side of each piece. In solving this type of puzzle, a full size outline drawn on a piece of paper or cardboard will serve as a pattern over which the pieces can be placed. Next month the solution to these two puzzles will be published. E. B. RoBERTs. seit big at

ho |" ol he | Vy; hes = =

% 2 ¥ GLUE TOP FIGURES FOR STOCK. LOWER FIGURES FOR 3%. Dimensions and plans for cutting the 14 or 1 in. square stock for the two new block puzzles. If enough readers request it, more puzzles of this type will be pub- lished. Address all requests to the Home Workshop Editor, POPULAR SCIENCE MONTHLY, 381 Fourth Avenue, New York City.

inger- touch TROL Bives you 1.Plain Drill 2.Left-hand Ratchet 7) a hig ht-hand Ratchet ® 4.Double Ratchet 5.Gears Locked

“*Yankee”’ Ratchet Breast Drill No. 1555, in use on airplane motor. (Photo- graph by permission Pit- cairn Aircraft, Inc.)

TWO SPEEDS a dependson the ‘‘feel” of the work, and you must know every instant where your drill is going and how it is cutting, the tool to use is a “Yankee” Ratchet Drill. With a “Yankee,” you drill fast or slow . . . change gears, high power or low . . . change ratchet adjustments. . . . All at a finger-touch and without re- moving drill from work. In tight places, “Yankee” Double Ratchet drives drill con- tinuously, on any slight forward- and-back motion of crank.

nai Any movement of crank, forward and back, no matter how slight, causes drill to cut continuously.

Pe es 4 “Yankee” Ratchet ad- justments bring awk- ward jobs out into the open, and speed up work.

Drilli out broken studs, and the like, calls for control given only by a “Yankee” Ratchet Drill.

aT e Use ‘Yankee’ Tap

No. 1555.—Breast Drill No. \ 1545.—Hand No. 1530.—Hand (illustrated). Length, 17 Drill. Length, 16 Drill. Only 10% Wrench No. 250. in. 3-jaw; \%-in. Double in. 3-jaw; %-in. in. but has the five Ratchet adjust- speed. Also,'2-jaw. $11.00. Double speed. Also, ratchet adjust- ments and sliding 2-jaw. Price, $10.00. ments. 3-jaw; %- cross-bar make in. Single speed. awkward jobs easy. Price, $5.25. Price, $1.85. YANKEE’ TOOLS MAKE BETTER MECHANICS

NORTH BROS. MFG. CO., Lehigh Avenue, Philadelphia, U. 8. A. I know the economy of good tools: Send me ‘‘Yankee’’ Tool Book, showi Bit Braces with famous “Yankee Ratchet, Quick-Return Spiral Screw-drivers, Automatic Push Drills, Ratchet Chain Drills, Removable-base Vises, etc. © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

(ice Ta eae NEN: <n e tehlne eae bance ae

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134 “T did more business this month than I did in a year filing saws by hand. I banked $161.66 which was accomplished in spare time and I can only attribute this new added suc- cess to my Foley because of its speed which enabled me to turn out four times more work.” Everett Myers. The Foley Model F-§ “3-Way” Si: Saw Filer Files all kinds of saws automatically so they cut better and stay sharp longer. Big demand for Foley-filed saws that pays steady profits. Start in spare time and build a permanent, fine-paying business. Easy Payments You can start in this profitable business with a small down payment and pay the rest out of profits in easy monthly pay- ments. No stock to camy. Easy and simple.to operate. Many men are mak- ing big money—-why don’t you? Free Pian Helps You Start Proved and tested plan tells you where to get the business. Many successful men have used it. You can make big money too. Get started now—send for this Free Plan today. Foley Manufactur 1013 Foley Bidg., 11 Main St. N. E., Co. inneapolis, Minn. You will be surprised to see how easy it is to play a Buescher Saxo- phone. Thousan‘slearn to play the scale in less than an hour. If you can sing or whistle you should play popular pie-es in less than two weeks and be ready to join a band or orchestra within 3 or 4 months. SAXOPHONE are easiest of all instruments to play because of the simplified Buescher fingering arrangement. Other patented Buescher features assure more beautiful tone, more accurate tune, easier blowing qualities and faster fingering. In a remarkably short time | many who did not realize they had musical ability have become experts on Bueschers and are now playing for big money in bands or orchestras or over the radio. 6 DAYS’ FREE TRIAL You, too, can quickly learn to = a Buescher. Prove it to yourself. Let us send you a Buescher Saxophone on six days’ free trial. Play it—use the free lessons. Your rapid progress will amaze you. Asmall down payment and a littleeach month makes it possible to pay while you play. Write | today for new Saxophone Catalog. (552) | BUESCHER BAND INSTRUMENT CO. i0s8sBuescher Block Elkhart, Indiana | POPULAR SCIENCE MONTHLY Marcu, 1930 NY reader who has had some experi- ence with concrete work will be inter- ested in the unusual examples of cement construction shown. They are the work of D. H. Frew, of Lisbon, Ohio, an editor and publisher. The garage was made from concrete panels 1 in. thick and 8 ft. long, which were molded in sheet iron pans. Iron molds were used to give a denser and smoother finish; in fact, the blocks are Each step was built in three molded sections, two pieces for the base and one for the tread. Reader Builde Comevene: Garage The garage was built four years ago and is at present without the slightest crack or flaw. practically waterproof. These panels are set in between 4 by 5 in. concrete posts. This garage, which was built for Mr. Frew’s own use, has been standing for four years and is without a break or a flaw. The steps shown were built for a library building in Mr. Frew’s neighborhood. Each step was made in three pieces, two pieces for the base and one piece for the tread. The treads were poured into a mold reénforced with iron rods, and trow- eled smooth after a little marble sand had been sprinkled over the top surface. Boiler Injector Removes Water from Cellars TORM water and seepage can be easily removed from cellar floors lo- cated below the sewage drain by the ingenious application of a steam boiler feed water injector. First, break through the flooring at the lowest point, place a 100-lb. white lead or similar can flush with the surface of the floor, and cement it securely in place. This forms the well for the drain water. Obtain a 34-in. steam boiler feed water injector and pipe the outlet of this to the sewage drainpipe. Run a pipe from the intake of the injector up to the ceiling and then down Diagram showing relative positions of the in- jector, water faucet, drain, and drainage well, to the well in the floor. This is done to obtain the added effect of a siphon system. Next, connect the pressure inlet to a water faucet by means of a piece of rubber hose held in place with clamps. To operate, all that is necessary is to turn on the water at the faucet. After the injector has been working awhile the pressure may be cut down, as the siphon action created in the intake pipe will tend to continue the flow of water. This idea was put to use by the writer to remove the storm and seepage water from a garage boiler room which was located 2 ft. below the level of the sewage drain.—RoBERT D, PEEBLES. Building Model Airplanes UCCESS in model airplane construc- tion depends, as in all crafts, not only upon the skill of the worker but on the tools that he uses. The novice, especially, will find that a set of a few specific tools will simplify and improve his work. A sharp pocketknife and a block plane having a 1-in. blade are probably the most important parts of the plane build- er’s tool kit. Two pairs of pliers, one round-nosed pair and the other of the flat-jawed type, will aid greatly in bend- ing wire into form, as in assembling landing gears and making wing clips. Among the miscellaneous tools are a large variety of sandpaper, a steel scale, an assortment of straight pins, a lead pencil, a small camel’s-hair brush, and a supply of model airplane builder’s ce- ment.—A. L. JACKSON. CLoccEpD plumbing fixtures are in many instances the result of carelessness. Dirty dishwater poured into the kitchen sink adheres to the walls of the trap and waste pipe. The coating of grease, together with other matter such as coffee grounds, and tea leaves, will block the drain. © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. MaRCH, —— Te ] HI tl encow! they : little 1 The 734 in is 74 wood small tio! scr scr oil pai du col ess re ~ wm © WwW

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930 Marcu, 1930 Toothbrush Holder Fosters Tidiness HILDREN are less likely to forget their three-times-a-day duty and are encouraged along the lines of tidiness if they are provided with the attractive little toothbrush holder illustrated. The design can be cut from a 34 by 5 by 73% in. piece of soft wood, since the figure is 74 in. high and 5 in. wide. If cigar box wood is used it will be necessary to glue a small strip across the back, along the sec- The figure is saw- ed from a piece of %-in. wood. &) %&§ tion marked for the hooks, so that the screw ends will not come through and scratch the wall. The figure can be painted with artists’ oil colors mixed with interior flat white paint to obtain the tints. This will pro- duce a flat finish. If desired, enamel can be used for the coloring. In this case it will not be nec- essary.to varnish the holder, and it will be readily cleanable-—ALBERT KOHLER. Mending Broken Pieces of Earthenware LACK iron enamel of the best grade * forms a very efficient cement for use in mending many small crocks or pieces of highly prized china. First, dry the piece of crockery or earthenware to be mended thoroughly. Apply the enamel to the crack with a thin piece of wood shaving, being careful to spread it on evenly all along the cracked edge. After a coat has been applied, rub the enamel into the crack. Allow this to dry and then apply a second coat. For an ordinary crack two applications. will be sufficient. If the crack is large, however, three or four coats of enamel will be necessary. After the final coat of enamel has dried, remove any surplus with a rag dampened with gasoline.—H. W. Swope. POPULAR SCIENCE MONTHLY 135 Buy when you're convinced We claim that, if you will accept our free 7-day shav- ing test, our chances are 86 in 100 it will win you. GENTLEMEN: Our advertising policy has always been a simple but effective free test offered men. We let the prod- , uct do its own selling. When you're convinced, you may buy. ... Palmolive Shaving Cream, in a few short years, has become the fastest sell- ing in the world. Millions of men who have sent for our free test have been won by it. 86%. of those who try it never return to old methods. Our problem is to convince you of the importance of making this test. For that reason we print the coupon prominently for your convenience. Will you mail it, please? ‘ 1 Multiplies itself in lather 250 times. Our 68-year old laboratories Our laboratories, for 68 years creating world leaders in the soap field, felt that olive oil in a shaving cream would do much, by its cosmetic emollience, to relieve the irritation and chafing of daily shaving. Time and again they tried to make a shaving cream worthy of the name 3 Maintains its creamy fullness for 10 minutes. Palmolive. 129 formulas were rejected before success came. Then we offered men for a convincing test, a product which embodied 5 important improve- ments. (See illustrations.) 5168 PALMOLIVE RADIO HOU R—Broadcast every Wednesday—from 9:30 to 10:30 p. m., Eastern time; 8:30 to 9:30 p. m., Central time; 7:30 to 8:30 p. m., Mountain time; 6:30 to 7:30 p. m., Pacific Coast time— over WEAF and 39 stations associated with The Nation- al Broadcasting Company. 7 SHAVES FREE and a can of Palmolive After Shaving Talc j / } f Simply insert your name and address and mail ik to Palmolive, Dept. M825, P. O. Box 375, | ai’ Grand Central Post Office, New York City. f Ef s Fs Z 5 Bine after-effects due to olive oil content. Biase pein yous anase and sideaa prada \ echegeie ek: sts SaaS Seen “OSI ee aOR 98" Rose

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“a "Let's put Jordan on the Job!” “I’VE BEEN PLANNING to promote him at the first opportunity. Now it’s here. Watson hasn’t been showing the interest in this busi- ness that I hoped he would. Jordan has been studying in spare time with the Interna- tional Correspondence Schools, They’ve sent me his reports and he’s doing fine! He’s ready. Put him in Watson’s place with full charge of the department. And tell the cashier to see me about his ealasy.. ‘ Great news for Jordan. Too bad ut Watson. But what can you expect? When an executive pro- motes a man he can’t afford to take chances. _ Are you preparing yourself for a better job and bigger pay? No matter where you live or how small rour means, the I. C. S. can help you. Find out how. fark and mail the coupon today! INTERNATIONAL CORRESPONDENCE SCHOOLS “The Universal University” Box 7657-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 X: TECHNICAL AND INDUSTRIAL COURSES Architect Automobile Work Architectural Draftsman [J Aviation Engines _) Building Foreman Plumber and Steam Fitter Concrete Builder Plumbing Inspector Contractor and Builder (] Foreman Plumber Structural Draftsman Heating and Ventilation _JStructural Enginee 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 i} Telegraph Engineer Chemistry Telephone Work [| | Pharmacy Mechanical Engineer Coal Mining Engineer Mechanical Draftsman Navigation (©) Assayer |} Iron and Steel Worker Textile Overseer or Supt. Cotton Manufacturing Woolen Manufacturing Surveying and Mapping LJAcriculture () Fruit Growing Bridge Engineer Poultry Farmin Gas Engine Operating [(] Mathematics Radio BUSINESS TRAINING COURSES Business Management Business Correspondence Industrial Management Show Card and Sign Personnel Management Lettering Traffic Management Stenography and Typing Accounting and C. P. A. LJ English Machine Shop Practice Toolmaker Patternmaker | } Civil Engineer Coaching Civil Service Cost Accounting Railway Mail Clerk Bookkeeping Mail Carrier Grade School Subjects High School Subjects Spanish (© French Illustrating () Cartooning Secretarial Work (J Salesmanship Advertising Lumber Dealer BIL. cdccconsscscsnccossoscocnnncsonssansnsnannsasuscnassttagesidaserscenccescoesecese Street SII, -nccccocecicascsisccnnsseneboiensbentoncsnnnsqnensheupentarbonssesecscetcncece TL 5, idanicpleibimadehidantinteepansliniel i iactiaintstnenahisnienilisscest STII, .. cocsccsccansapsonnesnensconnstnasenennnmneibiianeieieabeubuntedassooeces If you reside in Canada, send this coupon to the international Correspondence Schools Canadian, Limited, Montreal, Canada 7 CASH MONEY ~sand Plenty of it! We offer you absolutely FREE, o real opportunity for ready and $ surptus cash! Thiebig money-maker does not cost = one cent. $ Take ordersforthe porenally famous EDISCO TIES and genu- v' ine Broadcloth SHIRTS. ery man and young maa is your Every sale means big profits! CT NOW! WRITE US TODAY! The EDISCO line is yours for the asking. We send you FREE OF CHARGE, valuable Sales Kit showing actual cloth samples of EDISCO TIES and BROADCLOTH SHIRTS. Act Now! W rite Now! Just say “Send me the complete EDISCO line, FREE! EDISCO MEN'S WEAR CO., Dept. 23 1215 W. Van Buren St. Chicag Learn Cartooning At Home—in Your Spare Time The famous Picture ChartMethod of teaching original drawing has opened the door of success for hun- dreds of beginners. Whether you think you have talent or not, send for sample to test your abil- ity, and examples of the work of students earning from $50 to $300 Ft week. Please state your age. HE LANDON SCHOO 451 National Bidg., Cleveland, 0. POPULAR SCIENCE MONTHLY Wiring a Building Against Burglars Y INSTALLING a simple electric alarm of the type illustrated, you can efficiently protect a garage, chicken house, barn, or similar building against burglars. Even if the wires are cut by the thief the alarm rings. The system operates on a closed circuit which holds a relay open until the circuit is broken or a short circuit occurs, where- upon the alarm is sounded. Each window or door is supplied with a tripper so arranged as to open a small knife switch when an attempt at entry is made. The tripper device can be placed in such a way that the window may be left slightly open without causing the alarm to sound; but as soon as the window is opened far enough to admit the body swi oo BLOCK. WINDOW. Le PRAM CASEMENT , TOP HINGE a CASEMENT , SIDE HINGE 6-VOLT STORAGE BATTERY CHICKEN HOUSE RELAY. SWITCH TO DISCONNECT ALA If the window or door is opened far enough to admit a person, the relay circuit is interrupted. of a man, the tripper throws the switch, breaking the relay circuit. If a constant ringing bell is used, the alarm will continue to ring even though the opened window or door is closed quickly. Fuse links can be inserted at suitable places in the relay circuit, if desired, to cause the alarm to ring in case of fire. The materials needed are a 6-volt stor- age battery, a 200-ohm line telegraph relay, a 10-ampere, 250-volt knife switch, three dry cells, a 2'4-in. vibrating stroke or constant-ringing bell, sufficient No. 14 weatherproof wire for outside wiring and No. 18 annunciator wire for inside, and about 200 insulated 34-in. wire staples. If the line running from the house to the outside building is to be buried, how- ever, a lead covered wire should be used to insure absolute protection against moisture—RAyMOND R. STEWART and Emory W. Bryan. IN REPAIRING plaster walls, large patches of plaster will hold better if common nails are driven into the wood studs or laths. Sink the heads below the surface of the wall. Marcu, 1930 Free Lessons; NIGHTS ru) ALD 6 IN / STORF FOR Even if you can’t read a note of music right now, you play a simple melody on the very day you get your Deagan Xylorimba. Free, easy lessons show ou how. n you are amazing friendsand relatives, Then a new life begins—long, happy evenings of joy; parties; popularity: gadio Ca py ary: A wy same . make an aa m Chicago—*‘Played 20 minutes at wedding: received $20.” Or the Hallmann family, Reading, Pa.,—" $300 in 6 weeks, spare time,” FIVE DAYS’ FREE TRIAL—Our big FREE book tells all about this fascinating instrument—the 5-day free trial offer—the free lessons—the eas: mt plan. Send in the coupon today—the booklet wil be mailed. promptly without cost or obligation. MAIL COUPON TODAY! J. C. Deagan, Inc., Dept. 1653 1770 Berteau Ave., Chicago Send me, without obligation, full details of Free Trial offer and easy-payment plan on the Deagan Xylorimba. Name Address Here is everything yee need to gratify your crea- tive instinct. MAC — THE POPULAR ME- CHANIC isa real workshop, capable of delivering 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 we ee x offer the MAC on 10 days’ FREETRIALwithabsoluteguarantee V7 72) Of satisfaction or no sale. Instructions rman) 2 woodcraft are furnished FREE. ri ‘You Can Make lt ¥ 4 Experience the thrill of mak- These plans easily worth $2.50 — sent for ing things from wood. Send 25 cents today for 24 plans with 8 complete instructions for mak- - ing such articles as a Grand- Seam) father’s Clock, Book Case, Tables, Ship hy Model and many other useful articles. St A only 25 cents if you order now! Write for Complete Details Send now forliterature illustrating and describing MAC —THE POPULAR MECHANIC Workshop — details of our FREE TRIAL Offer, also liberal monthly terms. MIDLAND APPLIANCE CORPORATION 225 No. Michigan Ave. cE C2 CHICAGO STATIONARY * = Diesel Engines _Marine and Stationary By Ensign DAVID L. JONES, U.S. Navy The most, complete, thor- 85958 oughly practical and up-to- date treatise on the Diesel Engine ever published. It IESE NGINES explains their construction, troubles, remedies, operation MARINE and adjustments, practical OTIVE trials and tests and the ele- LocoM mentary thermodynamics of all wpe of the Diesel Engine. The book is fully illustrated with drawings of working ~parts and detail engravings. 400 pages. Price $5.00 Popular Science Monthly 381 Fourth Avenue New York, N. Y. © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. March, |} — Us By E driven prepar 106), applic finishil Star set up anothe not ru rub it no dil whole The the ened reme quire iron of t Star a pi righ’ will face and ther mor the spra abo spre hori at t in « Swi par the abr tha fac as All spe

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= wew Marcu, 1930 F Using a Spray Gun to Refinish an Automobile By EVERETT EAMES N EATNESS and cleanliness spell success in refinishing an auto- mobile with a small motor- driven spray gun. This is true in the preparatory work (P.S.M., Feb. ’30, p. 106), and even more so in the actual application of the priming coats and the finishing lacquer. Start with the hood, which should be set up on an old table or box and given another good washing with benzol. Do not run over the surface hurriedly, but rub it hard. After it seems as though no dirt could possibly be left, rub the whole surface with a lintless cloth damp- The sprayer should be held at about 8 in. from the work and kept in motion at all times. ened with thinner. During the cleaning, remember that the edges and seams re- quire the most attention. - Mix a pint of rust inhibitive red oxide of iron with a pint of thinner and fill the jar of the spray gun three quarters full. Start the motor and try the spray against a piece of tin. If the mixture is of the right consistency, a smooth, even coat will be deposited. A lumpy or pitted sur- face indicates that the liquid is too heavy and should be cautiously thinned fur- ther. If it sags or runs, it is too thin and more primer should be added. Now spray the hood all over the outside, keeping the spray constantly in motion and held about 8 in. from the surface. Move the spray at an even speed back and forth horizontally and keep it pointed directly at the surface at all times. Start the gun in operation away from the work and swing it on while spraying. Lap each parallel deposit about one quarter over the previous stroke. Never stop the gun abruptly on the work; swing it away so that any necessary joining of sprayed sur- faces will be “feathered.” Do not be startled by the appearance, as the correct color is bright orange. Allow the primer to dry one hour and in- spect for “wet spots.” If there are only POPULAR SCIENCE MONTHLY 137 Low... Room for a Real Basement Workshop and Den Heat may be produced by radiation—the transfer of radiant energy from the flame. HE coal bin torn out forever...complete 95 Py coavsition the freedom from the dust and dirt of coal eo Rees ts oe and ashes .. . your basement becomes a de- vection. lightful, liveable place with Silent Automatic. Plenty of room for a real workshop... where you'll enjoy making things for the home. Plenty of room, too, for a den, play- room or gym. Heat may also be pro- duced by condnchoa. Illustrated are all three methods of heat being tilized. Silent Automatic relieves you and your wife from every care of “tending” a furnace. Its uniform heat safeguards the family health. _ Silent Automatic Wallpaper, draperies and decorations stay aa a clean twice as long. ide eel te And Silent Automatic is so economical, and $fitiyhekertic can be bought on reasonable terms. Ask for °° #™* the names of owners among your neighbors; then ask them if they would ever be without it. Find out before you order more coal... | 12001 E. Jefferson Ave., for Silent Automatic can be installed in a | Detroit Michigan few hours, before the house chills. : fee the. Tocellig ligen ~~ shone’ ss eat for the fiome . | ; om hectsrerycar o oad Silent Automatic Corporation, Name | © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8 a i yo © ete ees ote

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138 WHEN YOUR LINE’S RUNNING OUT Four pounps of fish-power on a hook require all the attention you’ve got. And it gets it too— when you're in an “Old Town.”’ For the man in the stern can put an “Old Town” wherever a fish wants to go. That’s how easy they are to handle! Light — beautifully balanced — responsive to the blade’s slightest dip. y No wonder most fishermen choose “Old Town’’! Send for free catalog today. It shows and prices many models — all fashioned after Indian birch- barks, as low as $67. Also shows rowboats; din- ghies; big, fast, seaworthy, all-wood, outboard family boats, amd speedy step-planes. Old Town Canoe Co., 1153 Main St., Old Town, Maine. ‘Old Town Canoes” Infantile oe" Paralysis caused Carrie Tubbs to walk on the toes of her — foot. Photos and letter show how McLain Sanitarium helped her after 16 years: My right foot was crippled Infan- ti le pote fon ie 16 co from ye straight and useful. I think your work is wonderful and I will always recommend your Sanitarium to all cripples. CARRIE TUBBS, 1309 East 75th St. Los Angeles, California McLain Sanitarium (established 1898) is a private institution devoted to the treatment of crippled, defé and paralyzed conditions generally. No surgical Operation requiring oform or general anaes- thetics. Plaster Paris not used. Patients received without delay. Parents retain full charge of children if desired. Write For FREE Books “Deformities and Paralysis,” and “Ref- erences,” which show and tell of McLain Sanitarium’s facilities for treatin Club Feet, Infantile Paralysis, inal i and Deformities, Hip and Knee Disease, Wry Neck, etc. Alsoillustrated magazine, “Sanitarium News,” mailed | free every 60 days. ‘ McLAIN ORTHOPEDIC | SANITARIUM 840 AubertAv., St.Louis, Missouri, U.S. POPULAR SCIENCE MONTHLY Marcu, 1939 PLES OF 33 RARE Wi ALSO, 20 cabinet and 20 inlay, $1.75 — or your choice $1.00. Sets labeled and postpaid. We carry WOODS of all kinds, including Tite for Panels, veneers and inlay woods. W. FREE Price list. In stock—immediate delivery Gears, speed reducers, sprockets, thrust bearings, flexible couplings, pulleys, ete. A complete line is in our Chicago stock. also quote on special gears of any kind. Send us your blue-prints and inquiries. Write for Catalog No. 214. Chicago Gear Works, 769-773 W. Jackson Bivd., Chicago, Ill. a few small shiny places (% in. in diam- eter or so), they may be overlooked be- cause they will disappear as more of the finish is applied. If there are many spots or streaks, or one or two large spots, wash off the whole coat of primer with the thinner and scrub again with benzol and thinner. When judgment of cleanliness has been developed, apply the primer over the entire body. Between each filling of the paint jar, it should be half filled with thinner, The hood is used as the object for all first at- tempts as it can be easily refinished if necessary. shaken, and operated a few seconds to flush out the tubes and nozzle. If the gun does not discharge freely, partly clogged tubes are to blame; do not turn it against the car again until a full spray is deliv- ered. It is well to have three or four extra mason jars on hand, one for clear thinner and the others for different colors. Do not apply a heavy coat of primer— just enough to cover the metal thorough- ly. Allow it to dry at least an hour and sandpaper lightly with No. 280 paper or equivalent, using the paper dry. The hood may now be given three coats of surfacer, each coat following the other at intervals of at least twenty minutes. The surfacer behaves somewhat differently and is harder to lay evenly on account of its quicker drying qualities. Special pains must be taken to dilute it sufficiently to prevent the formation of a rough “orange peel” surface. A little over fifty percent of thinner will be re- quired. It is advisable not to stop the gun until the jar of material is completely sprayed, otherwise the tubes will clog slightly. If this happens, spray some thinner through the gun. After learning hew on the hood, proceed with the body. Do not be dis- turbed if the coat looks somewhat rough in spots; the sanding operations will eliminate all traces of such unevenness. However, it saves labor to lay the coat on smoothly in the first place. Now go over the surface for visible file marks or depressions and fill them with glazing putty. This should be allowed to set overnight and then scraped and sanded flush with the surface. The car should now be given a water sanding with waterproof sandpaper. Under the paper A Clean, Round Hole Genuine Russell Jennings Bits are trued in a micrometer, sharpened by hand, then tested in tough hickory. The keen lips cut a clean, round hole corresponding exactly with size of bit. The job is right. The full name, RUSSELL JENNINGS, is always on the shank. We place it there for your protcction. The RUSSELL JENNINGS MFG. Co., Chester, Conn. FLY THIS COMBAT MONOPLANE This realistic copy of a mil- itary monoplane is an unu- sually steady fiver. Wing- spread 18 in. eight only y% os. Will take off by own power and fiy over 80 ft. Markings in red and blue. Can be built in 2 . Con- struction set includes 6-in. aluminum propeller with shaft, 11, in. disc wheels, wood struts, rubber band motor and all other parts, hle bes clear ae yy Com- plete set, packed in unbreaka container, only $1.00, post- in U. S. and Canada. Order today, giving full address. Satis- or money refunded. The Midland Model Works, Chillicothe, Ohio ( We cannot make C.O.D. shipments. No retail catalogue issued.) Gseet INVENTORS COMPANY We Build Models Send us your rough idea. Our Master Mechanics will develop it for you into a practical working Model. Thirty years successful experience doing this very thing. Best shop equipment. Expert advice. Confidential service guaranteed. Bank reference furnished. Send for free booklet ‘“The Road To Success.” Crescent Tool Co. inci? Pt; *ynio GERSTNER ee] are Good CHESTS Machinists, Toolmak and_ other particular} mechanics appreciate their splendid quali- ties. atalog free. Write for it to-day. H. GERSTNER & SONS 575 Columbia St., Dayton. 0. IN WADE BENCH LATHE Cap. 4 in. dia. x 12 in. length. Sliderest has trav- el entire length of bed. d-serew _ inside Hollow spindle. Turning, facing, ring, drilling. winding, thread cutting. Z Lathe m-geqred headstech = re $42. . itn FA vy yeh : No Stopes ). — at equally low prices. Catalog sent fi THE GEROLD COMPANY Street, . P. S. 14, 120 Liberty New York NGER and make mone vy. Factory to Riders ¥:,2b'», 00 Sine eth fae pens ASTON, Tires sr vee share. 36 years. The Midget p, ;'Five;in-One” Slide Rule 8 combination Mannheim, Polymet- et ees subtract, multiply and diyide any com- fj] bination of whole numbers, fractess. mixed numbers and — : © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. Marcu, —_—_ hold a well so ly, ma any 01 of the sand ec sand smoot the pl ing Ww’ (not V The with | cloth coats. fifty | Ii t uppe! pape! the o first. anotl side ° not ¢ least and t with This liftec T: a gaso fore. “eve face gaso No. olin has of re trac an heig poli finis T line eno coa the Spr sev in «

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930 a a Marcu, 1930 hold a piece of folded cloth, and keep it well soaked with water. Rub rather gent- ly, making only three or four passes over any one spot. To check the smoothness of the surface, rub the fingers along the sanded parts as the work proceeds and re- sand all places that do not feel glass smooth. If any spots are rubbed through, the place should be resprayed after wash- ing with gasoline and a cloth dampened (not wet) with thinner. The whole car should now be washed with gasoline and wiped with a lintless cloth to prepare it for the lacquer finish coats. Three coats are required, using a fiftv percent dilution. If two colors are being used, spray the upper one first and then cover it with paper bound on with masking tape. Spray the other color in the same manner as the first. If a molding strip is to be still another color, cover the surface on each side with the tape before spraying. Do not attempt to peel the tape off for at least two hours after the last spraying, and then only after thoroughly soaking it with water applied with a paint brush. This will prevent any of the finish being lifted off with the tape. HE whole car is now to be sanded again with No. 280 paper soaked in gasoline and held over a cloth pad as be- fore. Sand gently and make strokes “every which way” until a glasslike sur- face is obtained. Wash thoroughly with gasoline and give another sanding with No. 400 paper. Wash again with gas- oline and wipe clean of all free color which has been sanded off. Spray on two coats of retarder thinner. This will smooth all traces of unevenness in tone and leave a natural gloss, which may be further heightened with any of the standard auto polishes compounded for use on lacquer finishes. To refinish the wheels, sand with gaso- line and waterproof sandpaper just enough to smooth the old finish unless the coating is badly flaked off, in which case the entire finish should be removed. Spray on three coats of finishing enamel, several varieties of which are available in quart sizes. To complete the work, spray the under- parts of the fenders with two coats of black lacquer; an inexpensive enamel will do if diluted with turpentine. The top should be painted with a brush in the regular way; that is, brushing lengthwise and using the dressing just as it comes from the can. If any work is required on the inside of the car, use a brushing lac- quer on the instrument board and spar varnish for the molding around the win- dows. If any striping is required, the car should be taken to a professional striper, as a steady experienced hand is necessary for this finishing touch. As a precaution against the chipping of the finish, run a safety razor blade along the edge of all metal moldings before the finish has thoroughly set. Cutting down to the metal in this way will prevent any slight movement of the parts from break- ing the glass-hard lacquer surface. Save any small portions of material left over, as they will come in handy to retouch scratches or scraped fenders. POPULAR SCIENCE MONTHLY TREASURE chest of bountiful health lies open to the Chris-Craft owner. Life on the water offers a multitude of thrills and pleasures not known on land. One may splash about at the swimming raft, take dinner at the distant yacht club, then Swing past a dozen miles of shoreline to evening social affair in remarkably short time. Chris-Craft days are full of joy: Go fishing, step out and win a race, entertain guests in delightful comfort, or just loiter among wooded islands. A whole new range of pleasures begin at the water's edge and all are spread before the Chriscrafter for his choice. Distinctive among the 24 models of the 1930 Chris- Craft fleet are the 20 and 22-foot runabouts. They are luxurious, deep-cushioned, 9 passenger Chris-Craft. They go like the wind, yet are sade controlled by boy or girl. They start, stop, steer, turn and reverse like an automobile, yet they are infinitely more flexible. Priced at $1895, the 20-foot Chris-Craft runabout is the lowest priced Chris-Craft ever offered. The 22-foot Chris Craft is listed at $2195 and $2595, offering a life-time of dependable water transportation. Illustrated catalog may be had by writing Chris Smith & Sons Boat Co, 363 Detroit Road, Algonac, Michigan. 24 CHRIS-CRAFT MODELS Runabouts— Sedans— Commuters — Cruisers — Yachts 20 to 48 feet-—$1895 to $35,000 World’s Largest Builders of 139 The 20-foot all mahogany Chris- Craft runabout is priced at $1895; the 22- foot runabout at $2195 and $2595. Chris-Craft All-Mahogany Motor Boats

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140 Reap the R. P. M. of any shaft or flywheel as handily as you read the time! Hold this VEEDER-ROOT Speed Counter in one hand; your timepiece in the other. No stop-watch needed. Check up motors, generators, engines, line shafting and machines which should run at specified R. P. M. for efficient performance. Save horsepower, lost motion, low produc- tion-rate with this little Counter which costs $3.50 (with 2 rubber tips). Circular fer the asking. ood. ROO ' J JNCORPORATED HARTFORD, CONN. OFFICES IN PRINCIPAL CITIES: WRITE OR PHONE We want to borrow a hand—the hardest-to- clean hand that ever did a dirt-collecting job. In 58 seconds we'll give back that hand so clean that its owner and his wife won’t know it. How will we clean it? With Lava Soap. That’s all. But that’s enough—because Lava is made to drag out grime and grease quicker than any other soap in the world—without hurting the skin. Lava contains pulverized Italian pumice ground almost as fine as flour. It makes a rich, fast-working lather—even in cold or hard water—a lather that gets the dirt and protects the skin. Lava costs only 6 cents or a dime—at any grocery or drug store. Gangs, Ue Fane Soop Man IF YOU’VE NEVER TRIED LAVA SOAP SEND FOR A FREE SAMPLE CAKE Procter & Gamble, Dept. X-330 Cincinnati, Ohio Send meatfreesample cake of Lava Soap. POPULAR SCIENCE MONTHLY Marcu, 1939 R the amateur artist who wishes to perform a novel stunt in home enter- tainment, ‘‘musical cartoons” are something new, amusing, and mystify- ing, yet may be performed without spe- cial talent or previous training. In fact, an hour or so spent in preparing the materials will insure a hit on any pro- gram. The performer stands blindfolded on the stage or platform beside a sketch board upon which is thumb-tacked a number of sheets of white paper. Simply by brushing a cloth over the surface, he causes pictures to appear in instant illustration of popular song numbers played on the piano by someone chosen from the audience. The necessary materials are a dozen or more 18 by 24 in. sheets of semiglossy paper (newspaper), a sheet of heavy wax paper of the same dimensions, and a 20 in. square piece of black cotton cloth which has been impregnated with pow- dered graphite. In preparation, the performer makes the simple sketches in pencil lines to the actual Size desired, illustrating the songs to be used. The drawings need not be perfect in detail, but can be rough car- toon sketches. These are the master or pattern sheets from which your blank sheets for stage use are made. Next place one of the patterns over a sheet of semi- glossy paper and, with a wax paper sheet between, trace over the lines of your pattern with the smooth, blunt end of a penholder. The pressure will cause in- visible lines of wax to be transferred to the blank news sheet beneath. Pro- ceed in a like manner with the re- maining patterns and your musical car- toons will be completed. The prepared sheets are then assem- bled in tablet fashion so that each one can be removed, or folded over the back of the board, on completion. Arrange now with some pianist to act as your confederate, ask her to take her place in the audience as one of the spec- tators. Give her a list of song numbers for which you have prepared illustrations and request that she memorize them. OU are then ready to begin your pro- gram. As the curtain rises to disclose your stage arrangement you address the audi- ence somewhat in this manner: “Ladies and gentlemen, I am about to reveal to you one of the most mysterious and science-defying powers of music— the transmission of pictures by the me- dium of sound waves. We are told that sound waves have been photographed, but never before have they been made to produge illustrations of the sentiment expressed, as they will do here. “Standing before this board, in the full view of everyone, I will cause pictures to appear before your very eyes; pictures made from the sound waves of any selec- —.., Mystify with Musical Cartoons By GERALD E. HENDRICKSON Three suggestions for cartoons. be sketched in a vigorous, humorous manner. They should tion that may be played upon the piano. I will employ no crayons, no pencil— nothing but this simple cloth which I will pass over the surface of the paper in order to fix the waves as they strike the sketch board. There will be no hidden movements of any kind, no covering of the sketch board, and yet an illustration in harmony with the melody played will instantly appear as soon as the strains of music begin. “‘Now, I am going to need the assist- ance of a pianist in this work and, to show you that there is nothing up my sleeve, I will ask some lady in the au- dience to kindly volunteer. She may play merely the chorus of any selection she desires. I request, however, for the benefit of the audience, that she restrict her selections to numbers that are famil- iar to everyone. These may be new or old, according to her choice.” Your confederate should not imme- diately spring to her feet and rush to the piano, but should allow sufficient time to elapse to avoid raising any suspicion of prearrangement. It is very difficult to procure a voluntary assistant for a pro- gram of this kind, as the very nature of the stunt suggests a “trick,” and no one will be very anxious to respond for fear of being made to appear ridiculous. .When your assistant finally presents herself, thank her for her kindness and request her to seat herself at the piano and to concentrate seriously upon the songs she plays. Warn your audience that strict silence must prevail to avoid confusion of the sound waves and resulting damage to the picture; then signal the pianist to begin playing the first selection, As the strains of music commence, wave the prepared cloth back and forth before the sketch board with an air of mystery, finally rubbing the cloth upon and over the surface of the topmost sheet of paper. The graphite in the cloth will adhere to the paper over the lines of wax and the picture will gradually take form. MARCH. —— Th proba! neer 1 passes invent provil auton or offe const! practi mitte inven nate 1 time : the D Dr, count neers. manu worlc meth Sout] reduc ated factu reco\ pine comy impr year’ esses leath prod prod iden Gre Ame Inst hon the Dr. of t D. | the: of | disc Bot Eco oral His ato! Ma wo! edu he | and and con une ize DR the the fan on bet ray sol ati dir int dit in co: su} sté ab at sit ur is tas

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— Marcu, 1930 — The Men Who Will Award Our $10,000 Prize (Continued from page 43) probably the most famous automotive engi- neer in the world. It is estimated that he passes judgment on an average of 350 new inventions each week. The thousand-acre proving station near Detroit, ewhere every automobile and automobile part produced by or offered to General Motors is teSted, was constructed under his direction, and thésevere practical road tests to which all.cars are sub- mitted were devised by him. He is also the inventor of the electrical devices which illumi- nate the dial, ring a bell, and print a slip every time a sale is rung up on a cash register, and of the Delco portable farm lighting system. Dre, ARTHUR Denon LITTLE, one of this country’s most distinguished chemical engi- neers, has worked out more processes of paper manufacture than any other chemist in the world. Not long ago, he developed a practical method for making newsprint paper from Southern woods, which promises an enormous reduction in the cost of newsprint when oper- ated on a large scale. Processes for the manu- facture of vegetable glue from starch, the recovery of turpentine and resin from yellow pine stumps, and the extraction of zinc from complex ores are among Dr. Little’s other impressive accomplishments of the last few years. In addition, he is the inventor of proc- esses for the manufacture of chrome-tanned leather and artificial silk, and has directed the production of a long line of alcohols and special products from petroleum. Dr. Little is pres- ident of the Society of Chemical Industry of Great Britain and past president of the American Chemical Society and the American Institute of Chemical Engineers. He holds the honorary degree of Doctor of Chemistry from the University of Pittsburgh. Dr. Joun CAMPBELL MERRIAM. As president of the Carnegie Institution at Washington, D. C., Dr. Merriam, since 1920, has directed of this great organization of research and discovery, which comprises departments of Botanical Research, Experimental Evolution, Economics and Sociology, Geophysical Lab- oratory, Marine Biology, Meridian Astrometry, Historical Research, Mt. Wilson Solar Observ- atory, Nutrition Laboratory, and Terrestrial Magnetism. Dr. Merriam is known for his work as a paleontologist, an administrator, an educator, and an author. As a paleontologist, he has distinguished himself by his discoveries and studies in the field of early forms of human and vertebrate animal life on the American continent, particularly in California, where he unearthed from prehistoric tar pits the fossil- ized remains of men and ancient animals. Dr. ROBERT ANDREWS MILLIKAN. Awarded the Nobel Prize in Physics in 1923 for isolating the electron and measuring its charge in his famous “oil-drop” experiment, Dr. Millikan, one of the foremost of living physicists, is even better known for his ben work in cosmic rays. In 1925 he ascended Mt. Whitney, in southern California, in search of a high, clear atmosphere in which to measure the extraor- dinary penetrating power of these short, invisible rays which bombard the earth from all directions. After repeating the experiment in Panama and Bolivia, he announced that cosmic rays Originated in the outer spaces, long supposed to have been empty, between the stars. He demonstrated that these rays prob- ably are the by-product of the birth of complex atoms, such as helium, silicon, and iron, out of simpler atoms such as hydrogen, and that the universe, hitherto believed to be deteriorating, is constantly being renewed. Dr. Millikan is chairman of the Executive Council of the California (Continued on page 142) the manifold and world wide scientific activities. POPULAR SCIENCE MONTHLY Shaves last - longer ... when small-bubble lather is used Millions of men testify that Colgate shaves last longer! Why? Because Colgate shaves are closer... smoother The unique “small-bubble” lather which Colgate’s makes on your face is vastly different from the ordinary, fluffy, air-filled “big-bubble” kind. These tiny Colgate bubbles get right down to the base of the beard, where the razor works (see diagrams at right). Also they carry much more water than big bubbles. Whiskers are simply drenched with mois- ture ... become soft and easy-to-cut. Your shave is closer . . . longer-lasting. Here’s exactly what happens when you lather up with Colgate’s: 1—the soap in the lather breaks up the oil film that covers each hair. 2—billions of tiny, moisture-laden bubbles seep down through our beard... crowd around each whisker... soak it soft with water. Instantly your beard gets moist and pliable ... easier to cut ... scientifically sof- tened right down at thebase ... ready for your razor. A comparative test is easy—just mail the coupon, now. We will send, also, a sample of After-Shave, a new lotion... refreshing, delightful ...the per- fect shave finale. 141 ORDINARY LATHER This lather- tly magni- fied) of tune doa cream showshow sir-filled bubbles fail to get down to the base of e beard; and how they hold air, instead of water, against the whi COLGATE LATHER This picture of Colgate lather shows how myriads of tiny, mois- ture-laden bubbles hold water, New York City. COLGATE, Dept. M-720, P. O. Box 375, Grand Central Post Office, Please send me, FREE, the seven-day trial tube of Colgate’s Rapid Shave Cream: also a sample bottle of “After-Shave.” Name Addr State.

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JhomP OUTBOARD MOTOR BOATS—For Every Pur- pose and Every Purse=The very fastest and most seaworth ot Type, V Bottem and Sled Type Boats for family use, and a strictly up-to-date line of Step Plane Racing Models to choose from. $48.00 and up— The most complete line ever offered, at real money- Saving prices. Canoes $50.00 and fi . . Some all wood, others canvas covered. Light, swift, safe, strong and durable. Choice of many distinctive color combinations.

With or without Engine. Fast, handsome six pas- senger craft at money-saving prices. CATALOG FREE — SAVE MONEY — ORDER BY MAIL Please state the kind of boat you are interested in (35) ———-—> TWO 4ZARGE FACTORIES > Mention Instrument ‘ < resait Lubricates ' Polishes | Prevents rust finest oil for protection of tools and all small ma- chinery. Never gums or hardens. Colorless, odor- less, stainless. Send direct if 3 5c your dealer cannot supply. Peee.. | Wm. F. Nye, Inc., Dept. R. New Bedford, Mass. Oil refiners for nearly a century

«a fray YY wr Ae

POPULAR SCIENCE MONTHLY

The Men Who Will Award Our $10,000 Prize (Continued from page 141) | Institute of Technology. He'holds’ honorary | degrees from numerous American and foreign universities. Pror. HENRY FAtrRFIELD OsBorN is president of the American Museum of Natural History, New York, which, in the twenty-two years of his administration, has developed into one of the greatest institutions of its kind in the world. His conception of a museum is a vast theater where people in all walks of life may view the great pageant of human and animal existence as far back as it can be traced. Be- fore 1908, Prof. Osborn was curator of the De- partment of Vertebrate Paleontology. In that capacity, he assembled in the Museum the most extensive collection of vertebrate fossils extant. Many of them resulted from annual expeditions under the Museum’s auspices, all of which he planned and many of which he accompanied. From 1891 until 1910, he was a member of the faculty of Columbia University. Since 1910, when he retired from active teach ing, he has been research professor of zoology. He is the author.of numerous scientific mono. graphs, the holder of many academic honors, and a member of a large number of learned societies. Dr. ELMER AMBROSE SPERRY, chairman of the Board of Directors of the Sperry Gyroscope Company, Brooklyn, N. Y., is considered by many authorities second only to Edison as an inventor. His reputation in the scientific world is based principally upon the Sperry search- light, which illuminates objects more brightly than sunlight; the gyrocompass, and the gyro- steerer, and the gyrostabilizer for ships. The three last are used by every navy and merchant fleet in the world. He also is the inventor of the Sperry aerial torpedo and many other imple- ments of war. In all, he holds about 400 patents issued in the United States and Europe, among them the Sperry carbide light; patents on electric street cars capable of climbing steep grades; electric coal mining machinery; and electrochemical processes for making caus- tic soda and chlorine salt. In recognition of his inventive genius, medals, awards, and other distinctions have been showered upon Dr. Sperry. He is one of the founders of the American Institute of Electrical Engineers and of the Electrochemical Society, and a member of several learned societies. Dr. SAMUEL WESLEY Stratton, president of the Massachusetts Institute of Technology, Cambridge, Mass., since 1923, and director of the United States Bureau of Standards for twenty-two years before that, is noted for his work as a physicist and as an educator. He is former secretary of the National Ad- visory Committee for Aeronautics, a mem- ber of the National Research Council, the International Committee on Weights and Measures, the American Institute of Electrical Engineers, the American Philosophical Society, the National Academy of Sciences. For his work in physics, Dr. Stratton has been awarded the Elliott Cresson Medal by the Franklin Institute, and the National Academy of Sciences has bestowed its public welfare medal upon him. He holds honorary degrees from Yale University, Harvard, and the Rensselaer Polytechnic Institute. Dr. Ettau THomson. Modern industry is indebted to Dr. Thomson for the invention of electric welding. He is the holder of nearly 800 patents for electrical devices, the most impor- tant of which are a three-coil armature for dynamos and motors, an induction motor, electric meters for direct and alternating cur- rents, and magnetic blow-outs for switches and fuses. His contribution (Continued on page 143)

© This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. Marcu, 1939

FORD TriMotor MONOPLANE

Model Airplanes — the IDEAL Way! Plans for Build this perfect, 3 Model Airplanes ft. | Model of the 25¢ each. famous FORD MONO- FORD MONOPLANE PLANE in which Comm. Fokker Monoplane Byrd flew over the South New York-Paris Pole. It is guaranteed Plane to fly. The ideal Con- Curtiss Biplane struction Outfit con- DeHAVILLAND tains everything needed; Biplane all materials with Plans NC-4 Naval and Instructions. Ask Sea plane your Model Airplane Bleriot, Nieuport dealer, or order direct. or Taube Monoplanes Cecil Peoli Racer. The price is....... $8.50 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.

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Marcu, 1930 — The Men Who Will Award Our $10,000 Prize (Continued from page 142) to present-day illumination is a constant cur- rent regulator for arc lighting dynamos—the device which took the flicker out of arc lamps. His career as an inventor and manufacturer began in the late ’70’s when, with E. J. Hous- ton, he was engaged in experimenting with electric dynamos. Dr. Thomson is the director of the Thomson Laboratory of the General Electric Company, at Lynn, Mass. He holds honorary degrees from five great American and English uni- versities and has been the recipient of numerous awards and distinctions, including an officer- ship in the Legion of Honor. Dr. Epwarp Ray WEDDLEIN, director of the Mellon Institute of Industrial Research, at Pittsburgh, Pa., has won a commanding posi- tion in the scientific world through his brilliant work in the production and assay of ores, especially copper, by wet processes, and his original researches in several other fields. One of this country ’s leading chemical engineers, he served as chemical expert on the War Indus- tries Board and as chairman of the fuel com- mittee of the National Research Council in: 1918 and 1919. Dr. Weidlein first attracted attention by his research work on camphor and on ductless glands. He is a past president of the American Institute of Chemical Engineers, a member of the American Institute of Mining and Metallurgical Engineers, the American Chemical Society, the National Education Association, the American Electro-Chemical Society, the Franklin Institute, the American Academy of Political and Social Sciences. Tufts College conferred the honorary degree of Doctor of Science upon him in 1924, HENRY HERMAN WESTINGHOUSE, 2 director of the Westinghouse Electric and Manufacturing Company, is a distinguished engineering execu- tive. Like his brother, the late George Westinghouse, inventor of the railway air brake, he began his apprenticeship to the machinist trade in his father’s shops in Schenectady, N. Y., and later studied me- chanical engineering at Cornell University. Since 1873, he has been connected continuously with the Westinghouse Air Brake Company, of which he is Chairman of the Board of Directors. He is also Chairman of the Board of Directors of the Canadian Westinghouse Co., Ltd., and of the Westinghouse Brake and Saxby Signal Co., Ltd., of London, England, and president of the Compagnie des Freins Westinghouse, of Paris, France. He is a trustee of Cornell University. Dr. ALBERT Easton WHITE, director of the Department of Engineering Research of the University of Michigan since 1920, is noted asa metallurgical engineer, ordnance expert, and educator. During the war, as a Captain and later as a Major in the United States Army, he headed the metallurgical branch of the Inspec- tion Division of the Ordnance Department. At the close of the war, he became head of the metallurgical branch of the Technical Staff, and now holds the rank of Lieutenant Colonel in the Ordnance Reserve Corps. Dr. White has served as consulting engineer with the Detroit Edison Company, the Packard Motor Car Company, and other industrial concerns. He is a member of the American Chemical Society, the American Institute of Mining and Metal- lurgical Engineers, the American Society for Steel, Treating, of which he is a former pres- ident, and other organizations. He holds the degree of Doctor of Science from Brown University. Dr. Wittts RopNEY WHITNEY, a chemist by education and training, is known most widely for his work in electricity, principally as the director of research (Continued om page 144) POPULAR SCIENCE MONTHLY 143 You Never Tire of It VERY motorcycle trip is a new adventure — every ride gives a new thrill—for motorcycling is one sport you never tire of. Ask any rider. When you get a Harley-Davidson you give yourself years of enjoy- ment, years of delightful recreation in the open air, years of the “great- est sport on wheels”. | And the cost is amazingly low. A. Harley-Davidson “45” Twin costs little to buy and almost nothing to run. Your local dealer has a Pay-As- You-Ride Plan that will interest ' you. Ask him about it—look RQ Qe “overthe wonderful 1930 models. e | HARLEY-DAVIDSON Mail the Coupon! for literature that shows the full line of Singles, Twins, HARLEY-DAVIDSON MOTOR CO., Dept. P. S., Milwaukee, Wis. Interested in your motorcycles. Send literature. and Sidecars. Mo- Name torcycle prices are Address My age is [] 16-19 years, [) 20-30 years, (J 31 years and up, as low as $235 “ (J Under 16 years. Check your age group. - f. 0. b. factory.

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a eR PE IE 2S nant a I a hp ent 2S ASLO? 14 C] what hundreds of men 6 are saying about the Foley Electra- keen Lawn Mower Sharpener business they have started. Last year Wood- 6) mancy earned $25 to $30 a day. Morse earned $1520 in five months. 6 Start Your Own Cash Business At Home Now! There is no other method for sharpen- ing lawn mowers to compare with the Foley. You can turn out perfect work quickly and easily. Simply put the lawn mower in the machine and turn on the power—the Foley Electrakeen System automatically sharpens ALL blades at once. Foley Electrakeen Lawn Mower Sharpener Uses same system as the leading lawn mower factories. Sharpens all sizes and types of lawn mowers. Costs you only le a job and you get $1.00, $1.25, $1.50 each. Walter Dambek writes, “I pur- chased a Foley Electrakeen Lawn Mower Sharpener three weeks ago and have already made enough money to pay for the machine and all expenses. ... ” Big Profits Can Be Earned There plenty of business waiting for you. Peopie would rather have their lawn mowers sharpened the Foley way because they cut better and stay sharp longer. YOU can start this business in spare time and make BIG MONEY! Small investment, easy monthly payments. Start Now! Send for Complete /@ information Joday “ Foley Manufacturing Co., 1439 Foley Bidg., 11 Main St., N. E., Minneapolis, Minn. Tell me how I can start my own Cash Business and make Big Profits with the Foley Electrakeen Lawn Mower Sharpener. @® @® @ @ Y2Qqq @ ®@ Name. Address re +r State ‘ DE | MAKE MUCH MONEY Making and Selling Your Own Goods. For- mulas by experts. Manufacturing Processes. Trade Secrets. All kinds. All lines. Auto- mobile Specialties. Cleaning and Polishing Compounds. Food Products. Toilet Prep- arations, etc. Send for interesting catalog, special circulars, FREE. C. THAXLY CO., Washington, D. C. or dramatic clubs, , ete., and for every \° T. S. Denison & Co. , 523 S. Wabash, Dept. 276 Chicago We ly all entertainment needs for POPULAR SCIENCE MONTHLY The Men Who Will Award Our $10,000 Prize (Continued from page 143) of the General Electric Company, at Schenec- tady, N. Y. One of his most important inven- tions was a submarine detector, used during the World War. As early as 1923 he demon- strated, on a laboratory scale, the transmission of “power by radio.” Recently, he exhibited a new device that may bring such transmission on a commercial scale a step nearer—the short- wave, high-power ZT-6 radio tube, which radiated sufficient power through the atmos- phere of a room to eht lamps without wires. He is working now on a “talking book,” using talking motion picture apparatus to record, without pictures, the entire content of a full- length novel. He holds honorary degrees from four Universities and is a member of numerous learned societies. ORVILLE WriGuHT, the first man to fly in a power-driven, heavier-than-air machine—De- cember 17, 1903—is world famous as the co- inventor of the airplane. For his accomplish- ments in the field of aeronautics, Mr. Wright has been awarded the Collier Trophy and has received honorary degrees from several Amer- ican and foreign universities and gold medals from more than a dozen organizations such as the Aero Club of France, Aero Club of the United Kingdom, Aero Club of America, the Smithsonian Institution, the Franklin Insti- tute, and the French Academy of Sciences. The Congress of the United States conferred a special medal upon him, as did the city of Dayton, O., where Mr. Wright was born. He was awarded the Cross of Chevalier of the Legion of Honor by France in 1909, and the Cross of Officer of the Legion of Honor in 1924. Mr. Wright is a member of the National Advisory Committee for Aeronautics and chairman of the advisory committee of the Daniel Guggenheim School of Aeronautics, New York University. Was Your Dog Once a Wolf? (Continued from page 57 dog family. From this ancestral type, he con- cludes, certain dog breeds deviated and be- came freaks because of the disturbance of their endocrine or ductless glands—especially the thyroid and pituitary. Thus the popeyes of the Boston terrier would be a symptom of goiter or thyroid trouble. The Pekinese and Pomeranian dog, counterparts of human dwarfs, would be the result of thyroid and pituitary trouble. The St. Bernard, according to Dr. Stockard’s theory, would have acromegaly, a bony overgrowth disease due to pituitary trouble; and the Great Dane would be the product of a sort of gigantism that corresponds to a rare human disease due to endocrine trouble. If Dr. Stockard’s explanation is cotrect, treatment with certain gland extracts should make bull- dogs lose all their prize-winning points and grow up to be police dogs. Should such a pro- cedure become regular practice, what may not be predicted for the dog shows of the future? The winning of a blue ribbon will be an arbitrary affair. Most recent evidence for the contention that all breeds of dogs were born from one common stock is afforded by the brilliant work of S. Harmsted Chubb, Associate Curator of Comparative Anatomy at the American Museum of Natural History. Testing a theory that all dogs run in the same way, he took action photographs of two in particular widely diverse in breed—the Irish wolfhound and the English bulldog. He found that, when they run, both dogs pass their hind legs outside their front ones, a difficult feat for the bulldog with its broad shoulders. But the deep-seated an- cestral habit crops out in spite of all man may do to alter the type by breeding. Marcu, 1930 Free A Medien Quick— Foems: If you work on ANY product that is used by concerns that serve the public; or used in business or homes, (for utility, beauty, or luxury)—GET THE FACTS that are back of this Tidal Wave of new quick thinking in all industries. .. A Look AHEAD, in manufac. turing, in methods, models, competition, costs, prices, Standards of Living. . . How—right NOW-—articles and parts are being made, far easier, faster, at lower cost; and “‘righter.”’ Fact-Sheets of Industry will give you a look AHEAD that will start you thinking; probably amaze you. Full CONTENTS OUTLINE is free; no obligation, Just state your name, address, company’s name and products, and whether you want the Facts for self or company. Postal will do, Or margin of this page. Save this. Do not trust to find it again; write NOW. Address: Fact-Sheets of Industry; N V F Co., Dept, C-1, Wilmington, Del. NV F Offer is by NATIONAL VULCANIZED FIBRE Company; its Divisions and Associated Industries. Special working methods; special Phenolites; “righter’’ Bakelites; parts, ma-' ways; Material Handling; etc.;. terials, and besides Vulcanized Fibre. Serving America’s Industries, from Smallest to Greatest. THIN HEAD MODEL 15° HINSDALE CHROME VANADIUM WRENCH SET Only $4 95 Guaranteed Plus Parcel Polished Nickel Heads penings Accurately Milled This ‘“‘thin-head” set of wrenches is invaluable for work on modern automobiles. Made of8.A.E. 6130 heat treated chrome vanadium steel. Kit- pack holds each wrench individually. Hinsdale Thin Jaw Pliers FREE—if you order from this ad. SEND NO NMIONEY Just write “Send C. O. D. parcel post one Hinsdale 15° angle Chrome Vanadium Wrench Set and free pair of Hinsdale Pliers.” Pay postman $1.95 plus parcel post charges. Money cheerfully refunded if you're not satisfied. HINSDALE MFG. CO. Established 1919 237 N. Desplaines St., Chicago, Ill. 6 Ft. LO aig TL gaa Pst Oar an PRR TA Sets baa . | CZ70l/ FREE! Boys! Here’s the it Navy model Airship. Large 6-foot air bag wit inflators, parachute with auto Pil arr ieee Meena oe tee Bek ill fly for miles at hei ‘ chance to study aerial ae EH Send name and spe- miedo: Sip hie ee nara C.M. THOMAS, 337 W. Madison St. 3K46 Chicago OLD COINS Large Spring selling catalog of coins for sale free to collectors only. Catalog quoting prices paid for coins, ten cents. William Hesslein 101B Tremont St., Boston, Mass. B * d In two-tone Artcraft (looks e leather—lasts forever) INGeEYD | iike teather—lasts f for with the name of the maga- ..| zine stamped in gold on Popular This bind ill hold A cover. is binder will ho —.. six copies of the magazine, on and new copies can be slipped Price $200 y as easily ‘as inserting a letter Postage Prepaid in an envelope. OPULAR SCIENCE PuB.isHinc Co. 381 Fourth Avenue New York City ® This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. Marci, | i r i 1

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rt ill n, 8 nt ot cant a | ee 1] Marcu, 1930 ~/ ~ Learn with your own hands inthe Great Coyne Shops! The secret of Coyne training is that it is all practical work. Here in the great Coyne shops you learn all about Electricity by actual work on a gigantic outlay of real electrical equipment the same as you will work on in the field. It makes no difference whether you’re 16 or 48—whether you can’t tell an armature from an air brake—I’ll see you through. No Books—No Printed Lessons You lose no time studying dry books or printed lessons, or memorizing puzzling theory. You go right to the aircraft engine, dynamo, or other equipment, and an expert shows you step by step all the secrets of electricity essential to your success. And when you’re through, our employment bureau gives you lifetime service. Railroad Fare Allowed Make up your mind today to get into one of these big pay jobs. If you act now—I’ll allow your railroad fare to Chicago and include these courses free! AVIATION ELECTRICITY, RADIO and AUTO- MOTIVE ELECTRICITY! And besides that, I help you to a part time job while learning! Don’t lose another minute— make this the turning point in your life. Send this coupon RIGHT NOW. POPULAR SCIENCE MONTHLY —— > Mla by w pH pe a These Coyne men are con- necting up, testing, and repairing A. y motors and controls. Operating and testing motor gener- ator sets at the great Coyne shops. r=§ | eg o@ us ECTRICITY is really easier Coyne students taping and put- ting in new coils in 200-horse- power A. C. stator. Coyne men wiring and oper- ating automatic controllers. felting ies EL than you imagine 145 WO weeks after graduation, Clyde F. Hart got a position as electrician for the Great Western Railroad at over $100 a week. That’s not unusual. I can name Coyne men making up to $600 a month. You can start a radio, battery, or auto electrical business of your own and make up to $15,000 yearly! How easy it is to clip and mail the coupon and find out how YOU could do it. Say good-bye to $25 and $30 a week. There’s a quick easy way to become a practical electrician in 90 days and qualify for jobs that , LEARN IN 90 DAYS by working with tools—not with puzzling ks, nor nerve racking pri lessons. esease for Jobs Like These Big Pay Jobs are com- Power House Operator mon in electricity. Our $50 to $75 a Week free employment bu- Auto Electrician reau. puts you in $60 CY Week and up touch with openings to Invent choose from. The fol- Unlimited Income lowing are only a few Engi of the kind of positions you fit yourself for in the —— Shops of p Service Station Owner up to $200 a Week Coy lo Expert Pore Li dehsing & Experts $60 a Week and up $60 yeek Contractor ow - YY Ex $3,500 to $15,000 a $50 t Year o $1 S week GET this FREE BOOK This school is 30 years old—endorsed by many large electri con- cerns. Simply mail the coupon and let me tell + ny all about it in the ig, free Coyne book. Mr. H. C. Lewis, President Coyne Electrical School, Dept. 30-73 500 S. Paulina St., Chicago, Ill. COYNE H. C. Lewis, President 500 S. Paulina St., Dept. 30-73 nes. 4. ELECTRICAL SCHOOL Established 1899 Chicago, Ill. Dear Mr. Lewis: Without obligation send me your b and all details of Railroad F ‘hicago, Free Employment Service, Radio, Aviation electrieit and Automotive Courses, and how I can “earn whi é learning.”’ BED sis 06000 bob sncdds Uivbeedese c sheebiworanee by CS OP RR EOE ee ery SOE eT EO ee free entalog lead to $50, $60 and more, in ELECTRICITY. it

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146 The Man with 6e the ” Grasshopper Mind r Mi Sacer” OU know this man as well as you know YOURSELF. His mind nibbles at EVERYTHING and masters NOTHING. He always takes up the EASIEST thing first, puts it down when it gets HARD, and starts something else. JUMPS from ONE THING TO AN- OTHER all the time! There are thousands of these PEOPLE WITH GRASSHOPPER MINDS in the world and they-do the world’s MOST TIRESOME TASKS—get but a PIT- TANCE for their work. If —YOU have a “Grasshopper mind” you know that this is TRUE—and WHY. Even the BLAZING SUN can’t burn a hole in a little piece of TISSUE PAPER unless its rays are concentrated ON ONE SPOT! Yet you KNOW you have intelligence and ability. WHAT'S holding you back? Just one fact—one SCIENTIFIC fact—PROVEN and stated by the world’s foremost scientists and psychologists. You are using only ONE- TENTH of your real BRAIN-POWER! The mind is like a muscle. It grows in power through exercise and use. It weakens and deteriorates with idleness. Increase your BRAIN-POWER and you will increase your EARNING POWER. But HOW? Spend 2c for a postage stamp. Send the coupon below for a copy of ‘“‘Scien- tific Mind Training.” This little book will tell you the secret of self- confidence, of a strong will, of a powerful memory, of unflagging concentration, of keen imagination—showing you how to _ banish negaiive qualities like forgetfulness, brain fag, indecision, self-consciousness, lack of ideas, mind wandering lack of system, procrastina- tion, timidity. Men like T. P. O’Connor, Prince Charles of Sweden, Frank P. Walsh, former Lieutenant Governor Lunn of New York, and hundreds of others equally famous, praise the simple method of increasing brain power described in this free book about Pelmanism. It has helped over 750,000 OTHERS during the past 25 years! You have only TWO CENTS to lose by writing for your copy. You may GAIN thousands of dollars, peace of mind, happiness, aes Don’t wait. Mail the coupon THE PELMAN INSTITUTE OF AMERICA Suite 873, 71 West 45th Street, New York City —_—— ee ee eee ee ee The Peiman Institute of America Suite 873, 71 West 45th Street New York City Please send me without obligation your free booklet, “Scientific Mind Training.” his does not place me under any obligation and no salesman is to call on me. POPULAR SCIENCE MONTHLY Why Tire Chains Are Safest (Continued from page 74) with a team of horses to pull him out. If he’d had chains along he’d have saved at least twice what they cost him.” “H’m,” grunted Morrison, “I hadn’t looked at it just that way. The darn things are so noisy and wear out so quick I kind of hate to bother with them.” “You can keep down the noise,” said Gus, “by using the spring tighteners, but you don’t want to get them so tight they don’t move on the tires, or they’ll cut through the tread in no time. As for wearing out, it’s a good hunch to put ’em on the other side out every time you apply ’em. You can get double the wear that way, because when you turn ’em over the wear comes at a different point on the link.” " ELL,” Morrison said as he climbed into his car, “‘I suppose now you'll try to sell me another pair to put on the front wheels.” Gus laughed. ‘“ No, I hardly think chains on the front wheels are worth while these days, when the tires are so large, though it depends a lot on the car. I saw a dumbbell the other day driving one of these new front-drive cars and he had the chains on the rear wheels. That would be just as foolish as for you to put chains on the front wheels and leave the rear wheels bare.” “What would you have done if you hadn’t any chains that fitted my car?” Morrison asked. “T’d have hooked on the service wagon and pulled you out,” said Gus. “That’s the easiest way. I only used the chains to convince you they were good dope. There are lots of ways to get a car out of a mudhole. The main thing is to remember that the two wheels can turn independently, so there’s no use in doing any- thing to the wheel that is stuck in the mud un- less the other wheel is on dry ground. If both of ’em are stuck, then whatever you do to one wheel has to be done to the other wheel, too. Sometimes you can get out of a mudhole by putting the brakes on a bit. That only works if the brake on the side that’s stuck holds a little tighter than the one on the pavement.” “WW7HY wouldn’t it be a good idea just to carry some pieces of rope in the car and wrap ’em around the tires when you get stuck?” Morrison asked. “That would work all right in mud or dee snow,” Gus replied, “but it wouldn’t be mu good on ice. Nothing is any good on ice unless it'll cut in the way chains do. Of course, if you’re going to do a lot of touring in a country where you are likely to get stuck in mud up to the hub caps every so often, it’s a mighty good plan to take along enough rope to give you a chance to use a block and tackle. If all four wheels get bogged in real soggy mud the easiest way to get the car out is to hook up a block and tackle to the frame, with the other end lashed to a tree or a stake driven into the ground, and just haul away until you pull the car through.” “Thank goodness, I don’t have to do any touring like that,” said Morrison. “Put on the other chain and stick the pair on my bill.” Helium Plant on Wheels ELIUM gas passes through nearly half a mile of copper tubing to be purified, in a mobile reclaiming plant developed for the Navy’s new airships under construction at Akron, O. The outfit can be towed behind a motor truck. Previously, gas-reclaiming plants were so heavy that they had to be mounted on railroad cars for transport. The new plant can meet an airship at the point of landing and restore its air-contaminated lifting gas to the standard purity of ninety-eight percent. Marcu, 1930 BcarnAVIATION WHERE LINDBERGH_STARTED ~0. =~ It’s the SSS Training That Coun ts! Aviation offers wonderful opportu- nities to the ambitious man. Pilots, ground men and mechanics, if properly trained, are in demand. Good salary, fascinating employment with unlimited ° opportunity for the future is yours in aviation. _ But don’t overlook the fact that the right kind of training is necessary. That is why discerning men pass up inferior training and come thousands of miles to get their training at this famous Lincoln School. Here you will get training from ex- perienced licensed pilot and ground in- structors who have been successfully training men for years. Here you will get training on modern production licensed training biplanes, monoplanes, open and cabin types. These you will find at the Lincoln School. Lindbergh Learned at Lincoln-- Our FREE Aviation Book tells the story. “Lindy” tells it in his book “WE."’ You, too, come to Lincoln and learn Aviation. Come‘to the Lincoln School. Take advantage of our expert instructors—our $250,000.00 worth of buildings and equipment—our reputation as the school that turns out better-trained round men and pilots. Come to Lincoln— OW—and get thorough, complete training that assures success! Get FREE Aviation Book! Contains full information about Lincoln School. ‘ells story of “Lindy” at Lincoln. Chock full of vital aviation facts. Tells about Big Money opportunities. Write today, stating age! LINCOLN Airplane & Flying School 218 Aircraft Bldg. Lincoln, Nebr. THE LATEST SPORT OF THE SKY Learn how to make and fly = a Glider—Safe and Excit- ing—Gliders are airplanes without engines—anyone can fly with a little skill— Build your own. Complete book on aero- mechanics teaches you how to build a practical Glider by yo f—simple and msive. The K contains 100 big Giqi Pages, beautiful four color S cover (size 9x12 inches), over 200 illustrations. This $2.00 Book} for 50c at all large newstands or mail 50c to: POPULAR BOOK CORP. 100 Park Place New York, N.Y. AN OPPORTUNITY TO EASILY Earn'100 a Week Profits = Advance 4 Sell Gibson extra fine men’s made-to- order all-wool suits at $23.50 and $31.50 direct to wearer. Biggest values— Most liberal commissions, with bonus, to producers. Frequent opportunities toget own clothes at no cost. Wedeliv- er and collect. 6 x 9 cloth samples— over 1C0 styles — complete outfitin handsome ing case furnished FREE to ambitious men who are willing to hustle. Write today. W. Z. GIBSON Pecan arom ea ee lg iting in eisens "work No text books, Old sheave wanted. efolirredaety evetzwacre senaubant recieve PAGE-CDAVIS SCHCOL OF ADVERTISING Dept. 1363, 3601 Michigan Ave., Chicago, U. S.A. MarkcH,

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Marcu, 1930 POPULAR SCIENCE MONTHLY RADIO NEEDS YOU Let RCA Institutes show you the way to SUCCESS in this fast-growing industry EACH out fora big-pay jobin Radio... Tie-up to the fastest-growing indus- try in the world today . . . See for yourself what other men have done... You, too, can do the same! Hundreds of fellows just like you are now earning from $2,000 to $25,000 a yearin RADIO. J.H. Barron, Radio Inspector of the U.S. Department of Commerce says that a most seri- ous shortage in trained Radio men exists right now. Thou- — sands of trained men are needed. Broadcasting sta- tions, manufacturing plants, retail and whole- sale dealers, as well as ships at sea and planes in% the air, require trained Radio men. Learn Radio at Home... RCA Institutes Will Train You for Success! RCA sets the standards for the entire ra- dio industry. The RCA Institutes Home Laboratory Training Course gives you the real, inside, practical training in Ra- dio, quicker than you could obtain it in any other way. It’s easy to learn at home in your spare time. You get your lessons and criticisms direct from RCA... the Clip this Coupon NOW ! RCA INSTITUTES, INC. SPONSORED BY Radio Mechanics earn up to $4,800 a year. very source of radio achievement . . . the vast world-wide organization that has made Radio what it is today . . . that sponsors every lesson in this course. RCA Graduates Find it Easy to Fill Good Radio Jobs There has been a radio job for practically every graduate of RCA Institutes. Gradu- oo ates are actually Trained for Suc- - cess because they learn radio by actual experience with the RCA Institutes famous outlay of apparatus given to every student of this course. You learn tosolve every radio problem such as repairing, installing, and servicing finesets. Hereisevery- thing you need knowin order to filla well-paid position in Radio. Send for this Free Book ‘“‘Radio... the Field of Unlimited Opportunity’”’ Read these 40 fascinating pages, each one packed with pictures and text that tell you everything you want to know about the many brilliant opportunities in Radio and about RCA Institutes, the world’s oldest and largest radio training organization. Tune in on Radio. Send for this free book today and speed up your earning capacity! 147 RCA INSTITUTES, Inc. Dept.[$M-3, 326 Broadway, New York Gentlemen: Please send me your FREE 40-page book which illustrates the brilliant opportunities in Radio and describes your laboratory-method of instruction at home! Formerly Radio Institute of America : DONG... nccsunstanducdesdionnahiéiitnnsnatibaeaeemaniaien | a Sane

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Siiitenens=s: oo L LE ee en nA

“I’m going to raise his salary” “I’ve had my eye on him for some time and I know he can handle bigger work. “He studies those I.C.S. textbooks every chance he gets, and I want to tell you it has made him a valuable man for this business. “I’m going to raise his salary and give him that new job we were talking about. I wish we had more men like him.” How do you stand when your employer checks up his men for promotion? Does he pass you by as just a routine worker, or does he think of you as a man who is ambitious to get ahead? Won’t you be far more likely to get the promotion if he knows you are studying at home and are really preparing yourself to handle bigger work? Think it over. Then act. It takes only a moment to mark and mail the coupon and find what the International Correspondence Schools can do for you, yet that one simple little step may be the means of changing your whole life. “Do it now.” mee eee ass ee rr iS OO US" INTERNATIONAL CORRESPONDENCE SCHOOLS “Tae Universal University’ Box 7656-F, Scranton, Penna. Without cost or obligation on my part, please send me a copy of your 48-page booklet, “Whe Wins and Why,” and tell me how I can qualify for the position, or in the subject, before which I have marked an x: TECHNICAL, AND INDUSTRIAL COURSES H Architect () Automobile Work Architectural Draftsman [J 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 . Positions Electric Car Running Highway Engineer Telegraph Engineer Chemistry Telephone Work Pharmacy Coal Mining Engineer Navigation () Assayer Iron and Steel Worker Textile Overseer or Supt. P Cotton Manufacturing Civil Engineer Woolen Manufacturing Surveying and Mapping LjAgriculture () Fruit Growing Bridge Engineer Poultry Farming Gas Engine Operating Mathematics () Radio BUSINESS TRAINING COURSES Business Management Business Correspondence Industrial Management Show Card and Sign Personnel Management Lettering Traffic Management Stenography and Typing Accounting and C. P. A, LJ English Mechanical Engineer Mechanical Draftsman Machine Shop Practice

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Marcu, 1930

Beating the Weather in the Air (Continued from page 148) from the tree tops. At 900 feet, I was above the down current and safe. A few months ago, I tried out a new super- sensitive altimeter for an inventor. On the take-off run, the hand of the instrument in- dicated the plane was fifty feet in the air be- fore the wheels left the ground. The partial vacuum, caused by the air rushing past the cockpit, reduced the air pressure within sufficiently to affect the instrument. In a strong wind, a similar partial vacuum exists on the lee side of every large building. In taking off at an air field, the pilot should head between the hangars instead of passing low over them. If he tries to skim just above the building on the take-off, his machine is likely to drop into the “dead air” and crash into the side of the hangar. EAR the ground, winds are usually stronger in the afternoon than in the morning. High in the air the opposite is true. It has been found also that the upper winds over North America tend to veer to the west. Among the mountains, on otherwise calm days, breezes move upward out of the valleys during the day and down into the valleys at night. This results from the heating and cool- ing of the ground in the depressions. One valley has become famous as a door that lets air mail flyers through the Allegheny Mountains in bad weather. It is the Woodward Pass. When clouds hang so low they obscure the mountain tops, the pilots take to the pass. The ships wind along the narrow channel under the cloud ceiling as though they were flying through a tunnel. They suggest fish swimming up a river under the ice. The flyers know every turn and narrow place. They could fly through with their eyes shut. Some of them even use the pass at night. Of all weather conditions, low clouds and fog are among the most dangerous. A pilot who takes his ship into fog is blinded. The ground and all landmarks disappear. It is like turning a corner in an automobile and being blinded by approaching headlights. Only in a plane you can’t slow down as you can in an auto. You have to keep going at express-train speed. Otherwise, you stall and crash. One morning I took off at Curtiss Field, N. Y., in a low fog to observe conditions at a practice field a few miles away. Instead of lifting, the fog began closing in. Everything turned as gray as an oyster. I headed for home, hedge-hopping along, sometimes lower than the telephone poles. The fog had become as thick as soup when I saw a plowed field below. With one wing dragging, I circled and pan- caked down a dozen yards from a boundary fence. WHEN fog is so thick that a pilot can see less than an eighth of a mile, the weather report gives “‘no visibility.” When he can see five miles or more, the report is “good visibil- ity.” Along the model airway established in California with the help of the Guggenheim Fund for the Promotion of Aeronautics, visibility conditions ahead are signaled by ground signs to the pilots as they pass over intermediate fields. White canvas strips, each three feet by fifteen feet long and laid flat on the ground, are used to form the signs. To indicate that the “ceiling,” or height of the clouds, is more than 2,000 feet, the strips are formed in the shape of a U. For overcast ceil- ing, but above 1,000 feet, the signal is a dash. For “come down, detailed reports,” it’s a cross. In flying toward a large city, a pilot often sees, from a distance, a cap of haze hanging over it. This cap is formed by dust and smoke particles in the air. When tiny droplets of moisture condense upon such particles, fog is

formed. <A new (Continued on page 150)

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150 POPULAR SCIENCE MONTHLY Marcu, 193) Marc#, | Thus Free Book | (> shows Beating the Weather in the Air (Continued from page 149) flying term, recently coined, is “smog.” It how rain, for means smoke-laden fog, one of the densest a you Can snowsto flyer meets. * up. Ev Pa WY \e RY In a fog or cloud the turn and bank indicator get into witl, st is the most valuable instrument on a ship. The on Without it a pilot might turn or side-slip with- with a a out realizing it. If he depended upon his senses & when t entirely, he might get into a tight spiral and easy to end in a spin, knowing that something was trasts | wrong but not exactly what. The air tubes ast © ie youn “aaa holes a connected to these instruments are now placed Sennite ‘answers to the dues field he closer to the motor than they used to be. Its tions you've been asking your. Ona . we heat keeps them thawed out when they might SS ee must ldo accide1 More and —s electricity otherwise become clogged with snow or ice. toget into Aviation?”—“"What run, tk lifting the weight of labor Walter Hinton how Uiputenans Walser tllasan as 1 ea from the shoulders of man. T° TRAIN my sense of balance I used to | rirst to pilot aplane {hough @ remarkable person- air, th If you are not satisfied with practice climbing through clouds without | across the Atlantic, give you RIGHT AT HOME sat do : ob. b looking at my instruments. Often I would get | {rst to fly from — _ the, gronnemintensive hese had b your present job, become an North to South ‘ : almost to the top, then lose my balance and | America, first to use study course in Aviation ie off the ELECTRICAL EXPERT come out in a steep dive ora side slip. During | the plane in explora- ears Graduates ta ol pacts a and free yourself forever the war, pilots had to be careful about coming ony ond cue| snaeea mes a W E rg nts ment service when you are from the discontent of low out of clouds that way. Once I tumbled out | home-stuay stude t service wh e right into the midst of three enemy planes. I ready for a job. If you want to > é , the cream of his ing. ' — You do not need any scuttled back for the cloud. We played hide | Knowledge. Cet Wal srranges for special reaased oo I previous training. Any man and seek until they set out after bigger game. pele cn tin ——,- an accredited flying plane who can read and write and Before a long cross-country trip, you should | Free Book, “Wings Send. for, this, book today. faces. use his hands can become prepare for bad weather emergencies. Famil- | ! Opportunity.” ing about Aviation could be bracii an electrical expert. > gee yourself = = —_ ——s fields 9 ee _ e way in case the ship is forced down. Make . : coate out a time-table showing when you should Mal 7 low fo" v 7 ach As s ° arrive at different points along the route so you flyer Here is Your can check your ground speed. Your air speed ; Watees inten. Ree 302-E : wher O tunit indicator shows your speed through the air | g 1115 Connecticut Ave., Washington, D. C. i temy ppor y only. A head wind cuts down your speed over | @ Please send me your Free Book showing howI @ feet a rw Vv - ELEC the ground and a tail wind increases it. . oe Se. at tl Che NEW YORK WC- On my last trip to Cleveland, I almost sat | g Name.........................055 ee . the | TRICAL SCHOOL pre- down in Lake Erie. It was “bird-walking | § ae Se eae tude pares you for the BIG PAY pores Me is ed a wen hag _ . AGGFESS . ....-- eee ee eee eee eee ete eee e eens H is st : 7 worst kind of air conditions ven the birds ET CES ae a’ tagee ese F “4 is learn have to walk.) As I neared the city, visibility | |. .wesseseseseeeneoeeaaed 7 © theoties Of electricity got so bad I was almost scraping the tree tops. t and then you put them into Then the rain began to pour. I was in a cabin ® Gallon the actual practice. You solve ~ be water Laaenres seme «dl — filters a und . a. “ so I could see almost nothing outside en cou poe ag — . “ the compass went “haywire.” I climbed and very 4 Minutes Riv CWS RONES. es ou nave headed in the direction in which I thought the ae kee completed your course at airport lay. The downpour began leaking into ) LowPriced-Guaranteed we the NEW YORK ELEC- the cabin. I saw it trickling over the instru- Amazing new invention— swe TRICAL SCHOOL you can ment board. If the water reached electrical ! patented Home Filter for Th non au nese of the weeld connections, the engine would cut out. I an on évtaoe P gales ar threw my hat over the switch to protect it. wh e sure of a g iving. int Write today for the 48-page [HE rain decreased a little. I dropped down "HOME bl: booklet giving full infor- where I thought the airport must be. Un- ‘a lifetime, ‘Thousands th mation on how to be an derneath was nothing but tossing waves. I FREE HOME TRIAL—A gents Wanted go : was somewhere over Lake Erie. Just before f risk and f 0) electrical expert. Try free at our risk and return if not satis- P the rain had begun, I had noted that the ground fied. Send name and address TODAY for full par- sO wind was from the west. I could see the waves ticulars of this liberal offer. Act NOW. AGENTS WANTED. to pitted by raindrops driven from what must be HOME FILTER CO., 763 CENTRAL AVE., BAY CITY, MICH. in the west, unless the wind direction had ee ee q changed. I figured I must have swung north in | ENGINEERING — ELECTRICITY n the fog. I took a chance and banked to the left. DRAFTING t Five minutes later, a white, line appeared ARCHITECTURE — b ELECTRIC AL ahead—shore breakers. I crossed the airport | Save time—enroll at this old established school of g twice in the foggy drizzle before I was sure I Star courses *"Biplonias rd B S'S. Degrees, n had arrived. I could hardly see when I set the Special 4 months’ ship down. Crash! She bounced a mile in the practical course in CHOOL - But I didn’t care. I was too glad to be Larceny peep . own on solid ground. —easy terms. Earn 40 W. 17th Street, New York putt MAIL _TODAY------= ! THE NEW YORK ELECTRICAL SCHOOL ¢ 40 Wesr 177TH Street, New York al Please send me FREE your 48-page booklet. It is understood that this request puts me under no obligation. eet Su Gaanoeoawoannoeeweaeanad That experience took place in autumn. At that time of year, rainstorms last longer and fog is thicker. But both occur less frequently than in summer. Ordinarily, a pilot is not forced down by rain. Many rainstorms are local. They can be flown through in less than half an hour. In an open cockpit ship, I have found it a good plan to have a rag ade to wipe off my goggles in a rain. Sometimes, however, you can see better in a hard down- pour if you let the water stream down the glasses instead of trying to wipe it off. In heavy rains, I have had to take off my goggles, — you learn. Free loyment bureau. A letics. Successful graduates evzry- where. Write he our free, illustrated 80 page ‘‘Blue Book.” It gives you all the facts. Address the Presi- dent, Charles W. Morey, B CHICAGO TECHNICAL COLLEGE mo Se cago. IL SONG WRITERS! Substantial Advance Royalties are paid on work found le for pub- nee Ce Se ed inal j lication. Anyone wishing to write etther : ) ee crouch down behind the windshield, and fly by Byte fb the instruments until the deluge lessened. 4 t nce unnecessary.New demand I a a a ae ade Even worse than (Continued on page 151) by pe Pictures’’. fully : Today—Newcomer Associates 758 Earle Building, New York, N. Y.

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939 RascarEeiat ieee Seeessigge eve Marca, 1930 Beating the Weather in the Air (Continued from page 150) rain, for visibility, is snow. In flying through a snowstorm, you can hardly tell which way is up. Everything becomes a thick, grayish-white swirl, streaking and slithering past the cockpit. The only direction in which a pilot can see with any clearness is straight down. And when the ground is covered with snow, it is easy to misjudge distance. There are few con- trasts in color. Snow also hides bumps and holes and makes a forced landing in an open field hazardous. On a snow-covered field, I once had a curious accident. The snow was soft. On the take-off run, the propeller kicked it up in chunks. Just as I eased back the stick and climbed into the air, the motor gasped and stopped dead. We sat down with a jolt. I found a mass of snow had been thrown into the air intake, choking off the engine. L ppensemen fog is called the airman’s greatest enemy, sleet in some ways is more menac- ing. You can keep flying in a fog as long asthe gas holds out. But sleet weighs down the plane and alters the curve of the lifting sur- faces. The ship is no longer able to fly. The bracing wires, coated with ice, double in size, increasing resistance. The propeller, irregularly coated with sleet, sets up dangerous vibrations. As soon as the sleet begins to accumulate, a flyer should drop to lower and warmer altitudes where the sleet may melt. On the average, the temperature rises one degree for every 300 feet a plane descends. It is ten degrees warmer at the earth’s surface than it is 3,000 feet in the air. If the sleet fails to melt at low alti- tudes, a landing is imperative while the plane is still under control. I WAS once up in a ship with a creeping throttle. The lever controlling the speed of the motor would work ahead if there were any undue vibration on the plane. I was flying a couple of thousand feet above the Hudson River, on my way to Albany. Near Pough- keepsie, a March drizzle set in. Then the weather changed to bitter cold. An icy wind swept down the river, freezing the rain to sleet. The wings became a glare of ice. They groaned and cracked at every gust. Ice formed on the whirling propeller. Chunks broke off and flew into space. The vibration from the unbalanced blades shook the plane. I jerked back the throttle for a glide to lower altitudes. My goggles had become partly covered with sleet. On the way down I tried to take them off. As soon as I removed my hand from the throttle to unsnap the helmet loops holding the goggles in place, the vibration from the propeller quickly pulled open the creeping throttle. The motor thundered. The machine shook like a tree in a storm. I was afraid the engine would be torn from its mountings. I didn’t dare let go the throttle again until all the ice had melted from the “prop.” In my sixteen years on the highways of the sky, I have met all kinds of weather. No two days are alike. Air conditions alter from hour to hour. Nowadays, planes take off under threatening skies that used to drive them into their hangars. They head into howling gales. Aviation is out of the fair-weather stage. So, more than ever before, a pilot needs to know his flying weather. Air Line Flag Stations LAG stops for airplanes, like flag stations for railroad trains, have been added by a transcontinental air line, extending its sched- uled service. Three such stops are at Vandalia, O.; St. Elmo, Ind.; and Terre Haute, Ind. At these points passengers may board planes by notifying the company’s representative, and passing planes stop for them on signal. POPULAR SCIENCE MONTHLY 151 R. T a R.T. l. 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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 Learning Radio the R. T. I. way with F. H. Schnell, the ‘“‘Ace 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 and start you off on practical work you'll enjoy— yeu 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 “ae date with last minute information. In a few weeks Dany can be doing actual Radio work, making enough E- 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. B R. T. I. trains your head and hands for money-making radio work. “Tune In On B 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 nae service. POSS. cc ccc ccscce CREF. o coccccccccses WHEN YOU — RT. TRAINED IN RADIO-TELEVISION - Talking Prchues Let F. H. SCHNELL and the R. T. I. Ad- visory Board HelpYou Twenty years Radio ex- perience. First to es- tablish two-way ama- teur communication with Europe. Former Traf. Mer. .——— Radio elay Lieut. 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152 Through. During the past few montis we have placed HUN DREDS of our graduates and also students when only half through the course—in well-paid Electrical pomeene, These men are now on the nigh 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. ot Go After the Big Money The big Electrical Utility magnates have just laid down a TWO-BI ON DO R program of new projects work. before President Hoover. Remember, that’s in addition to the billions already 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- copten, tricity. In your apare time, right at home, wa Railway OU Can now quickly master WIRING RS, NERATORS, POWER 3 at PLANT EQUIPMENT and other fasci- epereaata, nating branches of the work—and almost ,: , we'll be recommend- ter ‘ ing you for your first Electrical position. ank ag you revi §6§6!'WWWHO ELSE your «| jendig co- oogration, | Fe igped .. Wants A Good Electrical Job? 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 wai for you in Electricity —our fastest grow- ing industry. Mail coupon for an interesting pro tion we are right now to ambitious men. American School "27:5. St., Chicage 6 2 a eS ee Oe a AMERICAN SCHOOL, Dept. 3 Drexel Ave. and 58th St., Chicago, Il. Figace oqnd, mo without cost or obi jon Electrical bul- 0 ELECTRICAL ENGINEERING Business Oo Management Hecidies Mechanical Engineering Hekwencnsete Besctantaain (2 Auto Engineering O High School in 2 years i as ticteees esgic idan tainly hates cagianti a ictetnteaseipitinnin tt in aie nteteticditicaacnipenitidalintniiie Gv edthvddkcaneennmennéd Ce ee a SIR cesses cccccccacmsce Play the Hawaiian Guitar like the Hawaiians/ Only 4 Motions used in playing this fascinating instrument. Our native Hawaiian Instructors teach you to maste r them quickly. Pictures show how. Everything explained clearly. Playin Half Hour Easy Lessons After you get the Even if you don’t four easy motions know one note from you play harmonious another, the 52 eres with very printed léssons and Practice. No clear pictures make Geotteee musical iteasyto learnquick- nowledge needed. ly. Pay as you play. GIVEN when you enroll j HAWAIIAN GUITAR og Carrying Case WRITE AT ONCE for attrac: and Ftagtng Suctit ive er easy terms. a ‘ °o postcard will do. ACT! No A mame hn SA. OTHER ix Banjo, Violin. Tiple, Tenor Guitar, Ukulele, COURSES | Banjo Ukulele. Under well-known instructors. FIRST HAWAIIAN CONSERVATORY of MUSIC, Inc. Sth Floor, Woolworth Bidg., Dept 246 New York, N.Y. pereved os « Correspondence Seheot Under the La the BrEr Show York itomber Mattonel Home Study Conn uncil, POPULAR SCIENCE MONTHLY How Pygmy Tugboats Dock a Giant Liner (Continued from page 23) from the propellers. The three boats beside us have gone into action. At the bow of the liner on our side, two additional tugs strain back- ward on hawsers trying to drag the bow in toward the slip. They suggest a pair of puppies flattened out pulling ropes with their teeth. On the other side of the stern another pair of tugs are churning the water white as they | struggle at the ends of heavy lines, pulling the stern around into the tide. The Leviathan’s four propellers begin turn- ing, the ones on our side in reverse, those on the other side ahead. This has the effect of twisting | the liner in toward the slip, helping the tugs. } | The rush of water along the side of the vessel, from the reversed propellers, forces the tug nearest the stern to slide along the side of the | ship, crowding it against the Dalzellea. by the liner’s pro- ed. Near Pier 86, the HE water churned u pellers is roily, mud- | river is only about fifty feet deep at low tide. The draft of the Leviathan is more than forty. Thus, with little room for water to pass under the keel, the effect of swinging the huge liner broadside to the current, even a slight current, is like forcing a dam, forty feet deep and more than 900 feet long, upstream. Against this mountain of water, the eight tugs pit their strength. In winter, with ice piling against the upstream side, the difficulty of the maneuver is increased many fold. Looking on from the outside, such a struggle seems hopeless. It is when you see the power- ful engines that fill the tug’s hull, learn that the propeller on each tug is almost two thirds the size of one on the Leviathan, note the terrific drive of the little boats—sometimes they break four- and five-inch ropes—that you perceive in these awkward craft a strength fit for the battle. Tugs have been described as being “all muscle.” The description is correct. The engines of the’ Dalzellea develop between 850 and 1,000 horsepower. Sitting low in the water, its propeller ten feet below the surface, the little vessel has the forward drive of a sprinter getting out of starting.holes. In still water, this 100-foot, 180-ton tug can drag a 10,000-ton steamer at six miles an hour. HOWEVER, minutes pass while the tugs apparently churn the water in vain. Then the tip of a pier some distance up the river begins to creep slowly toward the liner. The bow of the Leviathan is swinging in. The pro- pellers on the big ship stop. The two “puppies” ahead cease straining at the hawsers, begin pushing against the side of the bow, holding it against the tide as the great boat turns more and more broadside to the stream. A small tug runs a twelve-inch rope, thick as a small tree trunk, to the pier. It is conrected to a windlass on the liner to help pull the bow in toward the slip. A second rope of the same size follows. As the ship moves into the slip, these ropes are “walked along,” moved from one pier mooring to another as the vessel progresses. There have been cases when even huge, foot- thick cables such as these have snapped like threads. The breaking of four- and five-inch ropes is a frequent occurrence in the life of a tugboat. Sometimes when two tugs are pulling in tandem, the cable parts. “What happens?” I wanted to know. “Oh, nothing much. The boats give a great exhibition of plowing up the water, but they don’t go far. They back up, take on another line, and begin again.” It was under such conditions, several months ago, I learned, that the quick wit of Captain Charles Coon of the “Grace A. Barrett,’”’ saved $200,000 in the space of a minute. While his tug was pulling the bow of a liner up against the tide, while approaching (Continued on page 153) Maxcu, 1939 +s \ KS Method of V; SEs svonbeck Geclaete en voles’ Now you can have the VOICE you want 100% = Y Improvement = \\ Guaranteed Beng ow SHLENT Wea Voice Book telling about amaz- ery - hh your \° us. Learn . ; to sing greater ease. 22 =p ever written. HowTo SecureA GovernmentPosition Why worry about strikes, layoffs, hard times? Government job! Increased sal: work, travel, good Clerk, Post Office Cler City ‘Mail Carrier, Rural Carrier—or get into any other Government job you want. I was a Secretary- Examiner of Civil Service Commission for 8 _— Have helped thousands. Railway Postal Clerk exam- ination coming. NOW FREE My 32-page book tells about the jobs open—and how I can hel ‘ou get one. Write TODAY. ARTHUR R. PAT- RSON. C ice Expert. PATTER- ig: SCHOOL. 163 Wisner Building, Rochester. ivil Serv: aries, steady pay. Examinations coming. I'll help you become a Cus- tom House Clerk, Railway Postal Get a mar. Held Make . $26 A Day and costs or $1.00 for sample dozen, wi new sure-fire self-selling plans. MASTERL Dept. RC-64 110 E. 234 St, ete. Write for catalog. ~ 451 ELLIS HALL No ogeets or A big 2Sc seller, paying 400% profit. A gross easily sold in a day brings $36.00 you $10.00. You make $26.00 clear profit. Rush $10.00 for gross, th amazing ITE MFG. CO. 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Marcu, 1930 How Pygmy Tugboats Dock a Giant Liner (Continued from page 152) a Brooklyn slip, the rope parted. Drift- ing with the current, the liner headed for a double string of railroad barges that had been “hung up” at the next pier. The great vessel’s momentum would have been sufficient to slice its knifelike prow through the barges and the freight cars they contained. There was no time for Coon to take on a new line or even to turn around. In the emergency, he did the only thing possible. He shot crayfish-wise against the bow, shoving backward in full reverse. The action deflected the course of the ship so it slid past the barges with only a glancing blow. Be- sides being a gamble with the unexpected, docking ocean liners is a battle of wits involving high stakes. A single dented plate on a big ship may mean a loss, counting repairs, demurrage, and wasted time, of as much as $80,000. With the Leviathan’s nose poked inside the slip, the two tugs at the bow ease their pushing. Protected by the upstream pier, the effect of the tide is diminished within the slip. From now on, the work of the tugs is easier. SINGLE whistle from the bridge. McLaughlin raises one arm. The tugs around us slow down to half speed. The harbor pilot leans over the rail, motioning inward to the two forward tugs. The bow has swung too far out. They fume and puff, shoving it slowly back to the “camels.” When at last the big ship touches all the “camels” and is made fast to the pier, the docking is completed. In winter, even after the vessel is inside the slip, the troubles of the tugboats are not over. Floating ice piles up between the pier and the ship, holding it out so far that the gangplanks will not reach. Then, two or three tugs have to churn back and forth, breaking up the ice and kicking ‘it out with their propellers. Others, attached to hawsers, keep the liner away; for, one squeeze between the sea giant and the pier would crush a tug like an empty eggshell, even though these small boats are probably the toughest of their size afloat. In heavy seas, with loaded barges lashed to each side, their groaning timbers withstand the nutcrackerlike crushings of the barges that come in from op- posite sides at the same moment. In Baltimore, one tug has withstood the daily pounding of active service for sixty-five years. Of the 700 tugs in New York Harbor, many are fifteen or twenty years old. No one can ride on these stout fellows of the water for long without a growing admiration for their sturdy power and tremendous capacity for taking punishment. At first they seem the ugly ducklings of the harbor. Their squat, bulging bodies, their pilot houses perched high above the deck like small heads on huge bodies, their mats of rope at the bow looking like mouthfuls of seaweed, give them a ludicrous appearance. On board, this unfavorable impression is soon lost in an appreciation of their virtues. NCIDENTALLY, there is a good reason for placing the pilot house some twenty feet above the water line. In rough weather, the galley and the engine room are closed so that waves breaking over the deck do no harm. Under such conditions, the tug weathers severe gales, plowing through the water almost like a submarine running at the surface. Once, Captain Howell was caught in a storm on Long Island Sound in which the wind blew sixty-five miles an hour. Before he reached port, a giant wave had crashed against the pilot house, break- ing a window. But storm or shine, day or night, winter or summer, the docking of ocean liners goes on. If conditions are bad, more tugs are called. Only fog can stop them. One week, last December, more than 100 ships were held off Sandy Hook, unable to dock because of fog. When the weather (Continued on page 164) POPULAR SCIENCE MONTHLY oil ile Mei eit 153 - au At Home aleleai Bleysy. Eee erates Mail Sketch—Get Free Rule. ENGINEER DOBE. . 1951 Lawrence Ave., Div. 1343 Chicage Here’s the sketch. Seat] ine ince suis alee y Pay Raina Pian,”— bow to earn money while learning and proof money paying positions. Name. Age. WORLD NEEDS Old style plumbers are fading | amy horse mands modern an ited, evift rowing fd. Make $50 i growing e te $100 a week or start ewn shop. We train you quick. Learn in 8-12 todo any job with skilland science. Need no previous experience. ing igate teday—amazing World's greatest school. Write— UNIVERSAL PLUMBING SCHOOL 2131 TroostAve. Kansas City, Mo. PLUMBERS Q . The world de- i d Skilled Strictly toolus- ity knocks. Inves- tuition. in a few months of practical instruction. No books or . No mechanical e - rience yo wens Dee. pay- school. Our schools located in Phila., Boston, Cleve- land, Detroit, and Chicago. 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154 Do You Make these Mistakes in ENGLISH? Sherwin Cody’s remarkable invention has enabled more than 70,000 people to cor- rect their mistakes in English. Only 15 minutes a day required to improve your speech and writing. ANY persons say “Did you hear from him today?” They should.say, ‘‘Have you heard from him to- day?’’ Some spell calen- dar “‘calender’’ or “‘cal- ander.”’ Still others say “between you and I”’ in- stead of “between you and me.”’ It is astonish- ing how often “‘who”’ i used for ‘“‘whom,” and how frequently the sim- plest words are mispro- nounced. Few know whether to spell certain words with one or two “s’s” or “m’s,” or “r’s,” or with “‘ie’”’ or “ei Most persons use only com- mon words—colorless, flat, ordinary. Their speech and their letters are lifeless, monotonous, humdrum. Every time they talk, or write, they show them- selves lacking in the essential points of English. SHERWIN CODY Wonderful New Invention For many years Mr. Cody studied the problem of creating instinctive habits of using good English. After countless experiments he finally invented a simple method by which you can acquire a better command of the English language in only 15 min- utes a day. Now you can stop making the mistakes which have been hurting you. Mr. Cody’s students have secured more improvement in five weeks than previously had been obtained by other pupils in two years! Learn by Habit—Not by Rules Under old methods rules are memorized, but cor- tect habits are not formed. Finally the rules them- selves are forgotten. The new Sherwin Cody method provides for the formation of correct habits by calling to your attention constantly only the mis- takes you yourself make. One of the wonderful things about Mr. Cody’s course is the speed with which these habit-forming practice drills can be carried out. You can write the answers to fifty questions in 15 minutes and correct your work in 5 minutes more. The drudgery and work of copying have been ended by Mr. Cody! You concentrate always on your own mistakes until it becomes “second nature” to speak and write correctly. FREE BOOK ON ENGLISH A new book explaining Mr. Cody’s remarkable method is ready. If you are ever embarrassed by mistakes in grammar, spelling, punctuation, pro- nunciation, or if you can not instantly command the exact words with which to express your ideas, this new free book, “‘How You Can Master Good English—in 15 Minutes a day,” will prove a revela- tion to you. Send the coupon or a letter or postal card for it now. SHERWIN CODY SCHOOL OF ENGLISH, 183 Searle Building, Rochester, N. Y. SHERWIN CODY SCHOOL OF ENGLISH, 183 Searle Building, Rochester, N. Y. Please send me your free book, “How Y ou Can Master Good English—in 15 Minutes a Day.” POPULAR SCIENCE MONTHLY How Pygmy Tugboats Dock a Giant Liner (Continued from page 153) cleared, a procession of fifty big vessels moved up the Bay and for twenty-four hours the tugs worked at top speed. The Dalzellea helped bring in fifteen in one day. The usual number is three or four. It was in thick weather off the lower tip of Manhattan that Captain Howell had one of his few accidents—a mishap that had its humorous side. He was helping haul a barge, loaded with more than two hundred sheep, across the bay when a vessel loomed up out of the mist and rammed the barge. It filled rapidly with water. In the emergency, Howell ran it alongside the pier at Governor’s Island, an Army base, and obtained permission to land the sheep. The commanding officer ordered all the soldiers out to join hands and form a living fence to corral the animals and keep them from overrunning the island. This maneuver would have been successful but for a frightened lamb. It madea dive between the legs of a big buck private and the two hundred sheep stampeded after it, tripping up the soldiers, knocking them down, and running over them in the mad rush. “ALL you would need to win a war,” Captain Howell says, “is a couple of million sheep!” It was a few minutes after twelve o'clock, noon, when the Dalzellea had first reached the high steel side of the Leviathan in midstream. It was nearly one when we heard McLaughlin’s final whistle and saw him waving us away. It had taken more than forty minutes to move the ship three times its length and make it fast. A record, made under ideal conditions during the war, is four and a half minutes. Down the flank of the Leviathan, from the bow, one of the “puppies” comes nosing along. Reaching the four tugs at the stern, it slices be- tween their bows and the side of the ship, turn- ing them out toward the river. They jostle and bump together, then separate and puff off downstream—the Dalzellea to bring i in a huge oil tanker, the others to go about various tasks. For putting America’s biggest liner to bed is only an incident in the day’s work of these tide- fighting, wind-fighting, ice-fighting craft of the harbor. Thousands Are Flying Gliders (Continued from page 21) ing point; speed, returning to point of depar- ture over a distance greater than one mile; landing on a mark. The skill with which machines can be brought down in “on the mark” landings was demonstrated during the Detroit meet. In a 28-mile-an-hour wind, five machines cut loose from towing planes at 2,000 feet and, one after the other, came down in spot landings. None of the five machines came to rest more than forty feet from the flag. Recently, a German student made a spot landing that was too accurate. Below him, he saw men putting up haycocks. He decided to show his skill by “sitting down” exactly on top of one of the piles near the edge of the field. He made the landing all right, but the mound he had chosen proved to be a pile of rocks. It “took his machine to pieces”—the gliding term for a crash—but left him uninjured. There are 300,000 members in the Airplane Model League of America. It is estimated that within the next few years half of this number will “graduate” into glider flying. New recruits are added daily to the army of those interested in the sport. The coming months will be the busiest in glider history, and new American records will be the aim of the hundreds who will take to the air in motorless ships of the sky. COLO COCOCOHE SOE eee Or Hee OOOOH OH Ess eeessese Marcu, 1930 WesstTer’s New INTERNATIONAL — A short cut to accurate Dictionary. companion for your hours of reading, wri and study that will quickly make itself indispensa le for its wealth of ready information on just the questions which most often puzzle you. A — yoo -at 106,000 Entries including the W WORDS, 1.700! may ate 3500, Fabrikoid, $6.00; Leather, $7.50. OOK 0 Oy + oN YY) 4 1 AY) a JOBS OPEN IN ELECTRIC REFRIGERATION : Now you can escape forever from crowded fields, poor pay, limited future! America’s newest and fastest growing pe yn Electric Refrigeration—needs trained men to fill service, sales, factory and Sees itions at salaries up to and $200 a week. Amazing new easy training qualifies you quickly at home in spare time-—endorsed and pane by Caneral Electric, Servel, ae. Copeland, Champion, Zerozone and other manufacturers. You Learn New Easy Way Unlike ordinary schooling. No textbooks. 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FREE = catalog fe a short course fo literature at is so re ph dg ey ee 10 book lovers CLARKSON PUBLISHING CO. CLARKSON BLDG., CHICAGO, ILL. Marc — H t In thou: whic com] plied this tion: Tecl 381 1. rin The | out abo the suff the — ww eee eet et et Ss" OO

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n it h h

Marcu, 1930

Here Are Correct Answers to Questions on Page 48 In the files of our Information Department are thousands of questions asked by our readers, from which these monthly questions and answers are compiled. What particular field or fields of ap- plied science would you like to have presented in this form in forthcoming issues? Your sugges- tions will be gladly received. Send them to the Technical Editor, PopULAR SCIENCE MONTHLY, 381 Fourth Avenue, New York, N.Y. 1. A piston type pump should not need priming if the piston is gas-tight and the valves the same, unless the pump is used to take water out of a well and is a considerable distance above the level of the water. In such a case, the air in the pump, being elastic, may expand sufficiently on the suction stroke, because of the back pressure, to prevent opening the in- take valve. If the cylinder is filled with water this cannot happen because water is not elastic. A centrifugal pump has to be primed if it is above the level of the water surface from which the supply is drawn, because no force is de- veloped unless water is rotated by the vanes of the pump. 2. Asteam locomotive is what is known as a prime mover. It develops mechanical power directly from fuel. It must, therefore, carry with it the power generating plant—that is, the boiler and the supply of coal. An electric locomotive, on the other hand, is simply a machine for transforming electrical energy into mechanical power, so that from a theoretical standpoint it should be possible to build a more powerful electric locomotive than steam locomotive within the weight limits that the track will stand. The practical limit is the horsepower required to handle the freight trains it is desired to pull. When it becomes practical to handle heavier and longer trains than are now being drawn, more powerful lo- comotives of either the steam or electric types can be designed to handle them. 3. Calculating the possible theoretical horsepower that could be developed from any waterfall is relatively simple. The area of the water actually moving over the fall is estimated or approximated by measurement. The speed of the water motion and the height of the fall also are measured. From these figures can be determined the weight of water that drops down the falls per minute, and the theoretical horsepower is determined from this figure, since it is known that a weight of 33,000 pounds dropping one foot in one minute is equivalent to one horsepower. 4. A tiny electric motor no bigger than an ordinary grapefruit may develop a quarter horsepower and equal in power another motor weighing fifty pounds and as big as a large watermelon. The little motor develops the power by rotating its armature at tremendously high speed, whereas the bigger motor would be rated for slower speed operation. In general, for any given horsepower output the oe at which the motor must run to develop this out- put determines the size of the motor. 5. A vacuum is not necessary to the opera- tion of a steam engine, but if the exhaust steam is led into a condenser where it encounters a spray of cold water it will condense and the pressure will drop considerably below the six- teen pounds per square inch which represents normal atmospheric pressure. Since this is the pressure on the side of the steam engine piston opposite to that against which the steam pres- sure is exerting its force, reducing the exhaust pressure adds that much to the effective pres- sure of the steam and raises the efficiency of the engine. 6.- A chain block (Continued on page 156)

POPULAR SCIENCE MONTHLY 155 Myou fellows who want to make more money:Radio necds more spare time _ and full time men 7 4

branches such as broadcasting stations, Radio jobbers, dealers, on board ship which gives you world-wide commercial land stations, and others. r a wonderful op- portunity to start profitable spare time or full time busi- ness of your own repairing, installing, servicing and selling travel without expense, Further, the growth of Radio has Radio sets without capital. Se Many Opportunities You Can Make Extra Meney et ee iene "the “how” Almost at Once Many students make $10, $20 and-even $30 a week in their spare jobs, what give you time. I will show you shortly after you enroll how to to charge, tell you what methods make money for tested ideas, tips, ¥ seaecr Earle Cummings, 18 Webster St., verhill, Mass., made $375 th spare time; G. W. Page, 1807 21st Ave., S., Nashville, Tenn.,'$935 in his spare time while taking my course. Don't worry. about paying the tuition—there’s no need to skimp— —— the world-famous course that pays for itself. Stay at Home—Learn in Your Spare Time Hold your job. Give me only part of your spare time. That's all I need. I know exactly what you need to know about Radio to be successful. You: don’t need a high school or college education. Many of my uates now making big money didn't even’ finish the grades. Boys 14, men up to 60 have-com- pleted my course successfully. ‘ Your Money Back if Not Satisfied That's the aenmens I — <—_ you. I'll send you a copy of my Money-Back Agreement with © my book, “ Rich Rewards in io.” ™ It Costs You Nothing To Find Out What Radio Offers You I have written a 64-page book “ Rich Rewards in Radio” on the different branches of Radio op- portunities, what salaries are paid, what the pose sibilities aré for the fature. I'll send you a freé without the slightest obligation to e Just tear out and mail the coupon Address J. E. Smith, President, Dept. OCO, Na- tional Radio Institute, Washington, D.C. Radio needs more men to take care of .its rapid. wth, Every year there are hundreds of fine jobs among ite many factories,

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

“Dont spoil the party” someone called when I sat down at the Piano —a moment later they got the surprise of their lives! “[TLL seem like old times to have Dan with us again.” “You'd better lock the piano!’ came the laughing re- joinder. How well I knew what they were taliing steam. At * last the piano and in my portg I had attended I sat down at us “chop-stick”’ fashion started pla: ying. Before long, however, I turned pend 4 and—the room was empty! urning with shame, I determined to turn the tables. To- ight my moment come. urning to Bill, I said, ‘“‘Hope you've had the piano tuned. . .” For a moment no one spoke. Then someone called: ‘For heaven's sake, don't spoil the party!”’ I Fool My Friends That was my cue. Instead of rep! I sat down at the piano and struck the first bars of “Sundown.” And how The guests gasped with amazement. When I finished there was | applause. demanded: “How did you do t?"’ “T just took advantage of a new way to learn music! There wasn't any expensive private teacher to pay, and I studied only in spare time, a few minutes a day. Almost before I ew it, I Play anything— , Thapsodies, waltzes, — ou, too, can learn to Diay year serene a men y this “9 LEABE nor aged home” method that has taught over half a million Mandolin Saxophone people. So sim you "Cello Bon't have to = the

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156 POPULAR SCIENCE MONTHLY ‘af 5) f - : : L. L. COOKE \s if =the man mak Big Pay Men | s. | \ MONEY 22 a» (;° ahead and feel bad for yourself—go ahead and os feel blue about the poor pay you get! But don’t 33084 blame anyone but yourself when so many men no Deer Mr. smarter than you earn $60 to $100 every week in the same six days that bring you only a paltry $25 or $35. They had no special luck—no “‘pull’’—no previous experience! But they - jumped into Electricity, the Big-Pay field, through ‘Cooke”’ ing of least S0e0 © Training. Now they get the big money! I showed them how! besides my 62 ‘1/20 And I’m ready to show YOU, too! we iS I'll Train You In Spare Time Your «ze, lack of experience, or lack of schooling is no drawback at all! All you need to know is how tor and write—and you'll be surprised how quickly I'll show you how to break into the Cooke: “I am making out fine. Have a shop of ® x Big Pay Electrical Field. All I want is a little of your spare time. And with my easily learned, quickly-grasped, right-up-to-the minute “Work Sheet” and “Job Ticket’’ Method I'll give you the ‘ same unforgetable training that has enabled many other men ect } to climb into positions paying up to $100 a week. My Course s Its Own Way | Not only do I give you the finest Electrical Training that you FROM 65c AN HOUR can get anywhere—the Training that Electrical Experts recom- TO $12 A DAY! angus ond great Electrical Concerns select for their employees Dear Mr. Cooke: & —but I show you how to earn as you learn. I teach you how to “A short time ago when I get spare-time electrical work, how to do it and what to charge. teste pene ys ey I —- And I give you, without extra charge, Six Big Outfits of tools aiieas tT tean ry” 3 sew and apparatus, with a real electric motor, so that your that will net me $12 a day. training is thorough and practical, and you’re equipped to Put me down as an L. L. do any kind of spare-time work that comes along! Cooke booster,” Act At Once — Mail Robert L. Korns, 217 8. Maybe it sounds too good to be true, but get the facts—de- Maple Ave.. Newkirk, Okla. mand the proof. See for yourself whether I do as | say here. NO EXTRA Find out all about “Cooke” Training and see why “The Cooke Trained Man Is the Big-Pay Man’’—always and everywhere! CHARGE /+THESE IG G OUTEITS. coupon for it this very minute! L. L. COOKE, Chief Instruction Engineer L.L. COOKESCHOOLIOF ELECTRICITY Dept. 33, 2150 Lawrence Ave., Chicago, Ill. oe 30 2p OM ©] OF GE O10) 08 210) Ns L. L. COOKE, Chief Instruction Engineer, Dept. 33, 2150 Lawrence Ave., Chicago, Illinois Send me, Free, your book, ‘Secrets of Success in | Electricity,” with particulars about your Home Study Course in Electricity. BE A RAILWAY PL. TRAFFIC INSPECTOR EARN UP TO $250 PER MONTH Big demand for trained Tra‘fic Inspectors. Pleasant, permanent, outdoor work with regular hours. Promotion rapid—unlimited opportunities. Travel or remain near home. We'll train you for this uncrowded profession in a few weeks’ spare time home instruction and upon completion, assist you to a position paying $120 to $135 per month, plus expenses, or re- fund your tuition. Rapid salary advances to $175, $200, $250 with = experience. Learn how your future can be made a certainty. Send for our free booklet now—it explains fully. Act quickly—men are needed now. STANDARD in Today — Write for my BOOK. Ican BUSINESS TRAINING make e te far my FRE "tow to Bsesens INSTITUTE a Good ~*” It con ile : “ig Solr temesraee Sarees WARS" iv Buffalo N. ¥. F.W. TAMBLYN, Kansas Gig Me E's. a. Marcu, 1930 Here Are Correct Answers to Questions on Page 48 (Continued from page 155) in its simplest form consists of a single toothed pulley to which the lifting hook is attached and a double toothed pulley attached to the hook that is to be applied to the beam or other support above. The two upper pulleys are side by side and of slightly different diameter. One side of the chain from the lower pulley is brought around the smaller upper pulley, and the other sid of the chain from the lower pulley is brought around the larger upper pulley. For each complete rotation of the up- per pair of pulleys the lower pulley is raised or lowered the difference in their two circum- ferences. If they are very close to the same diameter a tremendous pull can be exerted because the loose loop of chain must move through a great distance to raise the object very little. 7. The draft in a chimney is caused by the difference in the weight of the column of gas in the chimney as compared with the weight of an equal volume of air at ordinary temperature. Hot air or heated gases are expanded and are therefore much lighter than cool air. Conse- quently the gases in the chimney do not bal- ance the pressure of the atmosphere at the bottom of the chimney opening and air con- tinually flows in, to become heated in turn and its weight changed. The draft or flow of air up the chimney is maintained so long as the air or gas inside the chimney is hotter than the air outside the chimney. 8. If the motor boat is of the ordinary dis- placement type—that is, not a * age ss 8 the power required to double the speed is roughly four times. Thus if a six-horsepower . engine will drive the boat at six miles an hour a twenty-four horsepower engine probably would be required to drive it twelve miles an hour. The rule is not fixed, but varies with the speed, the shape of the hull, and many other factors. 9. If you hit a water pipe with a hammer a clanking sound will be produced. Water, being incompressible, acts like a hammer when the valve is suddenly shut. The flowing water rams against the closed valve and rattles the pipe as though it were a solid metal rod. Sees Chance of Creating Life Artificially IVING matter created synthetically in a test tube is predicted as a future ibility by Dr. Paul R. Heyl, physicist of the United States Bureau of Standards. Recent advances in the ability of chemists to duplicate nature’s substances, he says, are bringing this hope nearer. The first organic compound, a substance known as urea, was created synthetically as long ago as 1828 by a German chemist named Woéhler. Since then more and more progress has been made in duplicating natural compounds. A short time ago H. Fischer, a chemist of Munich, Germany, succeeded in making artificially what is known as the “respiration ferment,” the substance in the blood that aids the transfer.of oxygen for life processes from the red corpuscles to the tissues. “T think we are now within ‘shouting dis- tance’ of making protoplasm, of which living things are made,” Dr. Heyl declares. ‘When that is done, it remains to be seen whether our artificial protoplasm is dead or alive.” There is nothing mysterious, occult, or supernatural about any process of-life, Dr. Heyl says, and the so-called “spark of life” may turn out to be a simple chemical or physical process. Eventually, he predicts, all life processes will be as thoroughly understood as is the way that oxygen helps the burning of coal. Marci Just Fr U.S.

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Marca, 1930 POPULAR SCIENCE MONTHLY 157 Lwin My Patent Law At the right is a view of my draft- ing and specification offices where a large staff of experienced expertsare in my constant employ.

All drawings and spec- ifications are pre- pared under my per- sonal supervision. “ee Oe OV ae Se fee foe Offices <<“ Just Across Street a From P * U.S. Pat. Office ar 2 be s —— : E ifs os . & 7 a HFA peetastraaes spraeuationn sparse 1 “Rhee iu iT pes (6 ih iS 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 é 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 —— . So lose no il 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 pn law. We know the rules and requirements of the Patent Office. We can Lon,” proceed in the quickest, safest and best ways in preparing an application ae ; 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 author:zed members of my staff. Feel free to write me fully and frankly. _I tis probable that I can help you. Highest references But FIRST—clip the coupon a get my free book. THAT right now.

No Charge for Information On How to Proceed Mail this Coupon /ow . procedure that every inventor should have. And with it I will send you Cl ARENCE A O’BRIEN 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- Registered Patent Attorney 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 & Attorney-at-Law 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 88-V Security Savings and Commercial Bank Bidg, without charge or obligation. Clarence A. O’Brien Registered Patent Attorney Washington, D. C. L " a Suite 1106 Woolworth Blidg., New York City. Please send me your free book, ‘‘How to Obtain a Patent,’ and your “Record of Invention’ form without any cost & Attorney-at-Law or obligation on my part. Member of Bar of Supreme Court of the United States; ‘ Court of Appeals, District of Columbia; Supreme Court, I cenn:¢:b5.0 05.45 FEROAA ERED SETS SUERTE A TAO eR District of Columbia; United States Court of Claims. PRACTICE CONFINED EXCLUSIVELY TO PRIMED, SRAAe Ae Geren dns | Te Renede os ccanacivaswonnesnenscesaneepagenongs paseenst ) C/ aceererncrennnnennenesmammmemmenmmmmeneneny/< {P00 Wit Pauly and Address mow Newest You)

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Check and mail the coupon fi -—— Find Yourself Through LaSalle! ---=-4 ' LaSalle Extension H University | 1 Dept. 383-R Chicago § Please send me full infor- § mation regarding the course § and service I have marked § with an X below. Also Toy 4 § of “Ten Years’ Promotion § One” all without obligation ; to me. i 15 Business Management: Training for Official Man- H agerial, Sales and Departmental Executive positions, 1 C) Modern Salesmanship: Training for position as ’ Promotion Manager, 8 F Agent, and all ! positions in ret wholesale or specialty selling. | Hi A t for tion as | O iano, Comptroiier, Gertitied Public Accountant | Cost A Accountant, ete 1 0 Traffic powic Meee ement: Tra Tres Me 2° r pert, Freight Solicitor, etc. () Lew: LL. B. Degree. a and Fi for mas n mance: Training executive and Financial Institutions. for positions in 4 Shop Management, guch as that of aa General Foreman, Foreman, Sub-Foreman, etc. . ; eee for Works Production Control, Industrial En- En- | rsa rete Industrial Management: since O Oo OM Pe 1 Man 1 O Eisneger indus Relstions Mager Erp | ment my and positions in Employee Service. | om O¢ jodern Business Correspondence: Training for ! St or Collection Correspondent, Sales Promotion | Manager, Mail Sales Manager, Secretary, © etc, 1 Sten hy: Training in the new superior ma- hine ghorthand. Btenotrpy. = : 0 Railway Station (CO Effective Speaking Managemen’ OC. P. A. Coaching to Railway Accounting ( Commercial Spanish : 0 Expert Bookkeeping oO Stenotypy— 10 Business English Se nography : (—D Commercial Law (CD Telegraphy § D Credit and Collection Correspondence : CD Paper Salesman’s Training This INVENTION: "1000000 Housewives welcomed automatic thermostatic control on electric fron. Inventor made fortune. Wealth awaits you, too, if you concentrate; on things that are NEEDED. To make —. invention PAY BIG get Raymond Yates’s new %7000 Needed Inventions’’ Costs only $1.50 and directs your “inventive knack” along right lines. Find out what is practical and need- ed by industry and public. Book tells what inventions are wanted in fields of Radio,Automotive, etc. Send no money. Write postal. When book arrives, pay mail man if desired. Limited $1.50 plus postage. Money back, offer. Me ae | TODAY and prepare for real profits. (Outside U. 8. $1.70 cash with order.) BUREAU OF_INVENTIVE SCIENCE 23 Wisner Building, Rochester, N. Y. Flying with an Airship Captain (Continued from page 41) twenty-nine were safe and fourteen dead. Our noninflammable helium undoubtedly accounts for the many survivors. With up-to-date weather service, an airship is extremely unlikely to run into such a storm; but even if it should, I think the Los Angeles and future ships would have a good chance to weather it. And I expect future airships will have less to fear from storms of any kind, for increasing strength goes with larger size. Lightning is popularly regarded as a terror to airships—but that i isa fallacy. Even hydrogen- filled dirigibles have often been struck by light- ning with no more damage than a small hole fused in the metal bow cap. The metallic frame absorbs the electricity. I know only one authentic case of an airship destroyed by lightning—a German ship that was valving off hydrogen in a thunderstorm when lightning ignited the escaping gas and set the ship afire. The Graf Zeppelin, leaving Japan on its round-the-world flight, skirted a severe light- ning storm without fear of damage. ABELIUICF ILLED ship such as the Los Angeles is virtually immune. As an addi- tional precaution, the parts of the metal frame are carefully “bonded” or connected together so that no small spark, induced by lightning, could set fire to the gasoline. To test it, the entire hangar is darkened and electricity at ten or twenty thousand volts is applied to the frame. Sparks instantly reveal any loose con- nections. This was done to the Shenandoah when it was built at Lakehurst, and the Los Angeles had the same test in Germany. An airship ftying at night carries running lights just as an ocean liner does—but double the number. That is so that other aircraft can see her and tell her heading. The wisdom of this was demonstrated one moonlight night when the Los Angeles was flying between Philadelphia and Trenton, N. J. Out of the darkness a mail plane came roaring directly at the ship. None too soon the pilot spotted the lights and swerved out of the way. In a collision an airplane would no doubt suffer more than the airship. At most such a crash might puncture the envelope and rupture a gas cell or two, but there walihe plenty of reserve buoyancy to make port. The airplane would undoubtedly fall, a total wreck. The reason an airship is hard to force down is that the lifting gas is carried in separate cells inside the outer envelope, just as a steamer is built with water-tight compartments. ONE of the questions asked most frequently is what a dirigible commander would do if he ran out of fuel and no mooring place was near. In that case he would “free balloon” the ship—that is, fly it as a balloon and drift with the wind—to an emergency landing spot. Over the landing place, he would valve gas to bring the ship down, and check its fall near the ground by dropping ballast. For a land- ing place he would either choose the lee of a patch of woods or land the ship squarely on top of a grove of small trees. German airship men tell of landing wartime Zeppelins, out of fuel on the way back to their bases, on top of scrubby trees until a new fuel supply could be put aboard. I think the roughest airship cruising I have ever done has been over the mountains in the southwestern part of the country, both in the Shenandoah and the Graf Zeppelin. When strong lateral gusts strike, an airship may roll a little from side to side as a surface ship does. Unlike an ocean liner however, an airship sel- dom lists more than an angle of three or four degrees. I have never seen anyone seasick on an airship. Occasionally minor repairs are made in flight—patching a (Continued on page 159) Marcu, 1930 TO THE MAN WITH AN IDEA PATENTS Procured. Trade-Marks Registered. —A comprehensive, experienced, an service for the protection and levelopmen of your ideas. Preliminary advice gladly furnish without charge. Booklet of information and form for disclosing idea free on request. IRVING L. 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Figueroa, Los aaa Calif TRADE-MARKS DO NOT LOSE YOUR RIGHTS TO PATENT PROTECTION Before disclosing your invention to anyone send for blank form ‘‘Evi- DENCE OF CoNCcEPTION” to be signed and witnessed. * LANCASTER, ALLWINE & ROMMEL Registered Patent Attorneys 274 Ouray Biig., Washington, D.C. Originators of forms ‘‘Evidence of Conception” Send Be By Ear Seed ora At Home in Your Spare Time Stress 1 ‘you suo receve ey Mert A Benth of of Music Dept. 355 Niagara Fails, N. Y. this Free Book P ATE NT oinventions Edward Gottlieb ATTORNEY IN PATENT CAUSES 5 Beekman Street, New York Inventions Developed—Representative for Blair Tool and Machine Corp. Marc line, mos ing trip nect a cl thr C sca and lar; the len: | fine | abe |af | hu! | hir

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Marcu, 1930 —— POPULAR SCIENCE MONTHLY Flying with an Airship Captain (Continued from page 158) line, a rod, ora tear in the fabric. One of the most difficult repairs effected in flight was fix- ing the torn upper fin of the Shenandoah on a trip to St. Louis, in September, 1923. It was necessary to send three or four men to work in a cramped, dangerous position on the inside. A slip might have sent one of them plunging through the cover. On one flight we did have a “man overboard” scare. We had taken up a party of civilians, and were flying high when someone reported a large hole in the envelope at the after end of the ship beside the catwalk that runs the length of the interior. We were relieved to find the civilian who had punched the hole still aboard. He had gone exploring aft, and put a foot through the envelope into thin air. It hurt neither the ship nor him, but it did give him the thrill of his life. HE best illustration of the way that an air- | ship is flown, to my mind, is the fact that fog does not disturb us in the least. An air- ship navigates, not solely by landmarks, but by instruments. The altimeter tells us we are a safe distance from the earth. A magnetic or gyro compass reports our direction, and the air speed is known from an air speed meter. We measure the drift by sighting on a point on the surface of the earth; or, if we are at sea, by dropping a flare that ignites when it strikes the water. It spouts smoke and flame for five minutes and serves as a point of reference. Even an airplane pilot will see instruments that are new to him in the control room of an airship. One is a “gas pressure alarm.” When an airship rises, the lifting gas in the cells ex- pands because of reduced atmospheric pres- sure. Automatic safety valves release it before the accumulated interior gas pressure would burst the cells. At the so-called “pressure height”’ where the safety valves are about to operate, the alarm rings a bell and lights a light in the control.cabin. If the commander does not want to lose helium gas, he immediately checks the ship’s ascent. In the daytime the sun’s radiant heat raises the temperature of the gas in-the cells above that of the surrounding air, and in- creases its lift—despite the fabric of the gas cells, a foot of air space, and the envelope with its reflecting layer of two coats of aluminum “dope,” or paint. We call this temperature difference “superheat.” It is important for a dirigible commander to know it, so that he can avoid valving off gas to hold the ship down when the setting sun will soon make it heavy again—or dropping ballast, during the night, when the ship will tend to rise of its own ac- cord in the morning. He reads this important temperature difference from a “superheat meter” that the United States Bureau of Standards helped the Navy to perfect. At the touch of a switch it gives the “superheat” directly in degrees, at either the forward or after end of the ship. D&SPite the wide impression that an air- ship usually comes down by releasing its lifting gas, the normal way of landing the Los Angeles after a trip is to fly it right in. Head- ing into the wind, the motors are slowed until the ship is nearly stationary and then ropes are dropped to the ground crew. They haul us down by main force against the buoyancy of the ship. Occasionally some of the ground crew get a shower bath when the ship, coming down too fast, checks its fall by releasing a little of its water ballast. The Los Angeles provides an impromptu fire- works display when it lands at a mooring mast. She carries a Very light pistol, of possible use as a distress signal but principally used in the mooring maneuver. en the main cable is dropped we fire a (Continued on page 160) Our New Buildin Patent Office § Lawyers and Draftsmen. t } in regard to Patents, Trade-marks or Copyrights without charge. VICTOR BUILDING Nenety Opposite U. S. pecially Us for Our Own Use TRADE-MARKS AND ENT COPYRIGHTS OUR OFFER: or" your” wwextion 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. a ; , f £ { Hf berry tl A cen Alarm? fun 1] (ring | jim, Erected by 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 Countwies, 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. 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i f, I A fe 160 if Y F010 School at Hom —=_ io pi tld 4 lt tl! C4 ea 4 l oo ng arms ee neni t HIGH SCHOOL COURSE IN Trwe YEARS YOU ARE BADLY if you lack HANDICAPPED HiehSchool training. You cannot attain business or social prominence. You are barred from a business career, from the leading professions, from well- paid civil service jobs, from teaching and college entrance. In fact, em- ployers of tically all worth-while tions demand High School train- You can’t hope to succeed in the face of this handicap. But you can remove it. Let the American School help you. FIT YOURSELF FOR A BIG FUTURE This course, which has been prepared by some of America’s leading professors, will broaden your mind, and make you keen, alert and capable, It is com- plete, simplified and up-to-date. It covers all subjects given in a resident school and meets all requirements of a High School training. From the first lesson to the last you are care- fully examined and coached, USE SPARE TIMEONLY Most people idle away fifty hours a week, Probably you do. Use only one-fifth of your wasted hours for study and you can remove your present handicap within two years. You will enjoy the lessons and the knowledge you will gain will well repay the time spent in study. Check and mail the coupon NOW for full particulars and Free Bulletin, American School Deps?. H-248 Drexel Ava. and 38th $?., Chicade ee ee EN ete eo ee SE ee ee em oe oe School American Dept-11-348 = Drexel Ave. & 58th St., Chicago Sena me full informati bject checked Gad how yen Gil bale eens ok sly POPULAR SCIENCE MONTHLY Marcu, 1930 Flying with an Airship Captain (Continued from page 159) white star. Dropping the starboard yaw wire is accompanied by a green star, and the port yaw wire by a red one. This calls attention to the dropping of the wires, which may be dif- ficult to see, particularly at night. The ground crew respond with the same lights as they couple each wire to the corresponding ground wire. The Very lights are used both day and night, and the brilliant colored balls are easily seen in broad daylight. When landing in fog—as just a few weeks ago—the ship sometimes is brought down slowly by no: am gas. It is a little ticklish, but usually there are holes in the fog through which the earth can be seen and the landing cable dropped. Abroad there was developed a way of marking the landing field by captive balloons tethered just above the fog layer. Whistles sounded or guns fired at interval often help when landing a ship in the fog. RINGING an airship into its harbor has one big difference from guiding an ocean liner home. There is no “harbor pilot” who takes responsibility for the maneuver. The mooring officer, on the ground, directs both the take-off.and the landing, but the responsibility for the safety of the airship belongs to the captain alone. If the maneuver does not suit him, he can step in and give orders at any time. It is a weighty responsibility, but few diri- gible commanders would care to be relieved of it. There is a majesty about such a ship as the Los Angeles that those who have looked at her in her hangar know. Taking this great ship through the clouds is a thrill that comes to few men. For all her bulk, she is a graceful, responsive ship of the air—the forerunner of even greater liners of the future. **Smoke Ball’? May Account for Ball Lightning ANY are the stories of balls of fire that enter houses during lightning storms, are reported to roll or float about, and often at the end explode with a loud report and lingering smell described as “sulphurous.” Unfortu- nately such phenomena havea way of happen- ing, if at all, when no scientist is around to observe them. The following account, there- fore, of an experience of Professor George Winchester, Rutgers University physicist, given in a recent issue of Science, was especially interesting. It describes another strange phe- nomenon which offers some resemblance to ball lightning, observed-when the writer was motor- ing recently with his brother near Peoria, IIl. “Just as we were ascending a gentle slope a very brilliant lightning flash occurred .. . about six feet from the trunk of a hedge tree at our right we observed a ball of smoke about two feet from the ground. The ball appeared to be about eighteen inches in diameter and perfectly spherical. The color of this smoke, if it was smoke, was a yellowish brown. We could not find even a withered twig or leaf. We raised the question of whether this “ball of smoke” would haye been a “ball of fire” if the phenomenon had taken place after dark.” What caused this strange ball? According to a hypothesis suggested by a British chemist, E. Kilburn-Scott, to account for ball lightning, a bolt of lightning might possibly form a con- centrated globe of semiliquefied nitric oxide gas formed by the combination of elements in the air through the action of the electric spark. Such a gaseous ball would be of such a density that it would gravitate slowly to earth. It might be luminous at light, not so by day. Most significant, its outer layer would un- doubtedly react with the air, giving off brown fumes of a color like that described by Prof. Winchester. 34 Lesson Drawing Course The biggest value you ever saw advertised anywhere .. Haven't you often wished that you could draw cartoons, illustrate some idea, sketch some pretty face, etc.? You can do all of these things. One of America's most fa- mous Cartoonists and illustrators has as developed a great, simple system for “y success in all branches of Commer- © 2:38 —_—— — i cial Art. This system has revolu- tionized the entire theory of draw- ing. 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LaSalle Extens University, Regt. 382 Chicago who derive larg- est ne know and heed certain INVENTORS ==" facts before applying for Patents. Our book Patent-Sensée gives those facts; sent free. Write LACEY & LACEY F St., Washington, D. C. Established 186$ _ANEW INVENTION] © iT BAFFLES BURGLARS and SNEAK THIEVES _s ree icsafety ven dow lock. Easily hed to wind I ible for anyone outside to open window. Gives ventilation with absolute safety. 4 to 12 Locks needed in every home. BIG CHANCE TO MAKE $15 TO $25 DAILY Oo a me trea ever YBings. Endorsed round seller. Men and women HURRY--Be first to reap this golden harvest of Dollars. THE ELMWOOD MFG. CO., ‘1173 Elmwood Place, Cincinnati, @ ‘AGENTS! Sell Shirts ad sein et shirts. wfal Selling Qubfit FWEE POST. MaRcH, diseast but af cent ¢ the s¢ the I produ Psy make: other: is not or lac that « are “ sugge hypns condi W 1 of le study than skillf watc learn can This rop nt othe’ Lice gists hyp! 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Maxcu, 1930 The Truth about Hypnotism (Continued Srom page 28) diseased can be hypnotized to some extent; but apparently not more than twenty-five per- cent can with comparative ease be put into the so-called somnambulistic state, in which the most extreme phenomena are easily produced. Psychologists are not agreed as to just what makes some persons better subjects than others. Certainly the ability to be hypnotized is not a sign of weakness, lack of “ will power,” that easily hypnotized persons are those who are “strong-willed” and not easily open to suggestion in everyday life. And persons can be hypnotized “against their wills” under certain conditions. wr can hypnotize? The ability demands no unusual powers. It is simply a matter of learning how. Some hypnotists, through study and experience, become more successful than others, just as some surgeons become more skillful than others. Nearly anyone who has watched the process, especially if he has also learned about it by being himself hypnotized, can get some results in hypnotizing others. This is unfortunate, since those who lack proper insight into the nature of the hypnotic condition may be tempted to practice on others without foreseeing possible dangers. Licensed physicians and accredited psycholo- gists are the only ones who should attempt to hypnotize. Is hypnosis dangerous? In the hands of properly trained psychologists and physicians, no. There is no justification, however, for the use of hypnosis for entertainment. Unskilled amateurs might do all sorts of injury to their subjects. To produce exciting hallucinations and emotions in the subject might be harmful. An unscrupulous hypnotizer might take ad- vantage of a subject in various ways, though the subject probably could not be forced to commit actual crime, at least unless he were already a criminal. Moreover, unless care were taken to arouse the subject completely from the hypnotic state, and eventually to bring about recall of the hypnotic state, a habit of amnesia might be established which would possibly make the subject susceptible to later nervous disorders. If certain precautions are taken this danger may be avoided. ie HYPNOSIS is of such a serious nature, why hypnotize at all? There are certain justi- fiable uses. One is as an anesthetic. In 1837 a certain Dr. Oudet extracted a tooth painlessly under what we should now call hypnotic anesthesia. In the 1840’s surgeons, including James Braid, an English physician who coined the term “hypnotism” from a Greek word meaning sleep, employed a similar method for surgical operations and for the relief of pain in disease. Before the discovery of chemical anesthetics, hypnotic anesthesia might well have been employed more widely than it was, had the medical profession been less skeptical. This was before the common acceptance of hypnosis, about 1880. But now ether, novo- caine, and other anesthetics, easier to ad- minister and more certain in their action on all patients, have rendered the anesthetic use of hypnosis unnecessary. Even major operations might be performed, entirely painlessly, under hypnotic anesthesia. It is interesting that this is so, but ordinarily not practical. On.two occasions I have codperated with dentists, inducing hypnotic anesthesia while they have performed dental operations, filling and extracting of teeth without pain for the patient; but I do not recommend it, for there is no need of it. Worthwhile possibilities, however, lie in the use of hypnotic anesthesia for obstetrical purposes, and in cases of pain- ful, incurable dis- (Continued on page 162) or lack of intelligence. 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In a pe nm the charge you fix. the last few weeks I worked at my trade, machinist, full No training req , and machine set up in i j a few minutes. Plug into light socket bnd — a pba a also ground 97 mowers which netted start to sharpen. You Make Money Rig ht Away. SA ER Hundreds of dull mowers _stillwater, Minn., writes: “We set the machine up 2 wee H : are waiting to o Friday; since that time have sharpened 102 mowers.” in your local ity be shar pened. That's close to $200 in Kearney’s pocket for 2 weeks, work! Our Free Book Tells You How [2¢¢, men hers have made themselves independent—built substantial \\ permanent BIG PAYING businesses with this Ideal Grinder. Send for this book today—lIt’s free. SIGN THIS AND MAIL TODAY THE FATE-ROOT-HEATH CO. { 933-956 Bell St., Plymouth, Ohio, U.S.A: Send me the book that tells me how I can make my spare time worth $4 to $6 per hour. { If you work at Owners are looking for a place to get them p ntomes 9 No town too small. R. 8. 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162 Every day sees new accoi ta which it toward a tremen- lous future growth in the aeronautical indus- ba Why Should Young Men Learn Aviation? ban a, pa a a ee ye eee ae qddda<¢

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The Truth about Hypnotism (Continued from page 161) eases, such as cancer, that are beyond surgical treatment, to alleviate pain without drugs, but of course not to cure. Thus far, little has actually been done along these lines. Again, there is a general therapeutic use of hypnosis by specialists in the treatment of nervous diseases, and by psychologists co- operating with physicians. Many so-called shell-shock cases in the World War were cured by hypnosis. In many nervous diseases called tissue, yet the patient is really incapacitated. He may suffer from blindness, deafness, paraly- sis, headaches, indigestion, amnesia, and a host of serious illnesses without organic basis. Psychotherapy, along with proper medical treatment, is needed in such cases, and in some conditions hypnosis is the best method. One psychologist used-hypnosis to restore to a World War veteran memory for his identity after an amnesia lasting nearly ten years. Not long ago I had among my students one who had suffered for over four years from a constant headache following an injury when he fell on a fencing foil, the point of which pierced the eye socket above one eyeball. There was no ap- parent injury to the eyeball or optic nerve; but from the time of the accident there was blind- ness in the eye and a constant headache, such as one*might imagine would occur if a steel point actually were penetrating the skull. The best of ordinary medical treatment had failed to restore the sight or to stop the headache. One hypnotic treatment stopped the headache. The blindness in the one eye still remains with clinical indications at present that the optic nerve is really impaired; but in many similar cases functional blindness has been cured by hypnosis. N 1923 a World War veteran, also a student in one of mf classes, came to me for treat- ment for paralysis of one side of the face, a condition which had persisted since the war, and which physicians assured him was func- tional. Before he left my office after the first treatment by hypnosis, he was able to whistle for the first time since the war, and to smile with both sides of his face. Such cases are relatively. infrequent, how- ever. And hypnosis, psychoanalysis, and other forms of psychotherapy, though needed in the treatment of some kinds of disorders, are in general time-consuming and for this reason more expensive than ordinary medical and surgical treatment. By the method of psy- choanalysis many months are often needed for adequate treatment, and with hypnosis there have been cases of successful results only after 100 or even 500 treatments. Sometimes the patients who most need such treatment are very difficult to put into the hypnotic state. THIRD, there is the experimental and in- structional use of hypnosis by psychologists in the study of abnormal psychology. Demon- strations can be made of a wide variety of the unusual conditiens of consciousness and be- havior, of hallucinations, paralyses,. double personalities, and the like. Subconscious proc- esses, of which the main part of the personal- ity is unaware, may be produced experimen- tally and controlled. The experimental demonstration of the reality of subconscious intellectual opera- tions first occurred in 1886. In 1901 William James, whose name is outstanding in the history of American psychology, referred to this demonstration as the basis of the most important discovery in psychology since he had been a student of the subject. The nature of the experiment was as follows: The subject would be put into the hypnotic state. A prob- lem of some sort, often a mathematical prob- lem, would be given (Continued on page 163)

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Marcu, 1930

The Truth about Hypnotism (Continued from page 162) to him. Then the subject would be awakened instantly from hypnosis, before the problem could be solved. The subject then would be in his normal state, without memory even of the fact that a problem had been given. But when a ouija board was given to him, the answer to the problem would be spelled out, the subject being unaware of what it was all about. Now- adays such an experiment usually is varied, as by the use of an ordinary pencil instead of the ouija board. Then we obtain what is called automatic writing—writing which is inde- pendent of voluntary control or even aware- ness, but produces words, sentences, and even long compositions such as would ordinarily require conscious, voluntary control. It is thus an excellent demonstration of subcon- scious processes. Hypnosis is a useful method of initiating automatic writing, but the latter may come about independently of hypnosis. Some per- sons find themselves able to write whole vol- umes of prose or poetry by means of the ouija board (automatic spelling) or by auto- matic writing with a pencil. A woman in St. Louis has published several volumes, the com- position of which has occurred in this way. Being unaware of any participation in the authorship, and lacking psychological insight into the matter, she ascribes the authorship to the disembodied spirit of a woman, Patience Worth, supposed to have lived long ago. By experiments involving hypnosis and automatic writing, such feats may be duplicated in principle, in simple form, without need of “summoning spirits from the vasty deep” for their explanation. The source of such com- position is the spontaneous expression of a sub- merged fraction of a person’s personality. NoR is it a rare and difficult feat to produce automatic writing. In group experiments with my classes in recent years I have been able to initiate it by a technique resembling hypno- sis in about twenty-five percent of the class members. In one such experiment in 1925, for example, I asked the members of the class to think of some childhood Christmas scene. One member soon wrote, without any awareness of what he was writing (I quote with a change of name): “Sally Ann Jones. Skates. Tree.” This meant nothing to the subject when he came to read it. Two months later I asked him to come to my office. I used hypnosis simply to the extent of closing his eyes so that he could not see his hand as it was writing. He took a pencil in his hand, and when told that he would write unconsciously an explanation of the previous writing, the following writing at once was forthcoming (again I quote with a change of the name of the town): “Eh, I remember that was my nurse who cared for me when I had the measles in Valley Ridge, New Jersey. She told me she would give me a pair of skates when I recovered. I got them at Xmas time. I was five years old when I had the measles. She was tall and blonde and was very pretty. She was the daughter of a manufacturer in Valley Ridge, and was engaged to be married. Her beau used to come over to see her quite often. He used to bring me candy and things to play with.” The subject was not aware that his hand was writing, and later when he read what had been written, it meant nothing to him, since he had forgotten the incident described. Consultation with his parents, however, verified the accuracy of the writing. This subject was a healthy college student, a member of the football team. Experiments of this kind are’ useful in “de- bunking” many superstitions, in “taking the spirits out of spiritism,” in showing that un- usual processes like automatic writing may actually occur without requiring anything occult or “psychic” for their explanation.

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C-244, 1418 Pendleton Ave., . ‘orld’s Largest Manufacturers of Mechanical Stroppers 8 KRISS KROSS CORP., Dept. C-244 r 1418 Pendleton Ave., St. uis, Mo. Without obligation, please send me illustrated i description and full details of your special intro- ductory offer on KRISS KROSS super stropper ] : and FREE 3-way razor. i State 2 Check ‘here it interested in making money ! ) 88 authorized KRISS KROSS representative. | Ae eee ee eee ae ee =——— POPULAR SCIENCE MONTHLY Threads That Swing 350,000 Tons (Continued from page 25) spinning of these strands into the cables of the Hudson Bridge, is now under way. It will be completed next October. To manage it, two temporary footbridges each twenty-five feet wide had to be slung from one anchorage to another, a feat in itself. The cables for the footbridges were the first to cross the river. They were fastened, first, to their anchorage on the New York shore. Then a barge, towed slowly across the river by tugs, id out the cable from reels. Unwinding, it y on the river bed where it would not inter- fere with passing steamers. Once across, the ropes were firmly fixed to the Jersey anchorages. Then cranes on the bridge towers reached down and hoisted the long steel cables to saddles on the tops. The same afternoon that the first cables for the footbridges spanned the river, there was lively discussion among the workmen—a hard-boiled, rollicking, fearless lot—as to who would have the honor of being the first to cross. A supervising engineer looked down one of the shining steel ropes and saw what looked like two buzzards roosting 400 feet out. They moved—and the engineer recognized them as two of his star workmen suspended on the naked wires 250 feet above the water. “We're crossing to Jersey!” they replied to his outraged hail. Threatened with instant dismissal, they returned to wait for the foot- bridges. ITH the footbridges in place, the spinning job began. To spin a‘ single cable, which consists of sixty-one strands, each made of 434 wires about the thickness of a lead pencil, a traveling wheel makes 26,474 trips across the river. It unrolls the wire from a reel fixed on one of the anchorages, and lays each successive wire next to the last. When a spool of wire gives out, wire from a new spool is spliced on. Completing a strand of sixty-one wires, the next wire is spliced on in the same way. Thus the wires in a main cable will consist of a single unbroken filament. When finished, the four main cables of the bridge will contain 107,000 miles of wire, enough to wrap four times around the earth at the equator. A zinc coat protects the wire from the weath- er. When all the wires of a main cable have been spun, a traveling machine crosses the footbridge, squeezing them together under enormous pressure into a compact three-foot circular cable. Thus the cables will support a road in the air, 200 feet above high water. They will last as long as the bridge, which has been designed as nearly permanent as engineers know how to make it, and they afford another striking example of the power of cables put to work for civilization. Stage Scenery of Paper HE cost of stage scenery has been reduced from thousands of dollars to thousands of cents at the Grand Theatre in Geneva, Switzerland, by an ingenious method of sub- stituting paper for wood and other more ex- pensive compositions ordinarily used in the fabrication of scenery. This innovation is said to have made possible the production of a musical revue at a cost under one hundred dollars. Brightly colored paper, chemically treated to make it relatively fireproof, and of a trans- parency that allows the creation of novel light- ing effects from behind and from in front, com- prise the new scenery. It has the advantages of being extraordinarily light and easy to han- dle. Authorities report that the scenery for a short musical production offered between the acts at the Geneva theatre could be packed in ‘two ordinary traveler’s trunks, and cost less than fifty dollars. Marcu, 1930 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. Now they are doing work they like—making good money—and have a real chance to advance still further. Why We Recommend DRAFTING It will pay you toin ing. You'll find many te Draft- Contracto aghuaenn — suc on rs, seeiate and Executives STARTED in the Drafting room. Starts at $40 Theworkisinteresting and pleasant. a Week 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 beginn up to $5,000 a pg 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. Jobs When You’re Only Half Way Through! We have recently develo a@ re- markable placement ice which enables us to find good positions for students when only half way through the course. These men are making RAPID progress because they are combining spare-time — —_ practical experience on e job. with the Muncie Over 70,000 Drafting positions Oil En ine Co. I fn apne 1 : a g the past year. a pies your Here is one of the biggest fields you ald in ae can get into. Right now we oo ba making an interesting proposition Maurice N. to ambitious men—mail coupon for Barcham complete information. American School De7t:}:i46, Drexet Avenue i a ee ee en AMERICAN SCHOOL, Dept. ’ Drexel Ave. and 58th St., Chicago, Ill. Please tell me, without cost or obligation, about your and employment service in line marked X below. C DRAFTING oO D Business Management D Building DO Accounting Steel 0 Mechanical Engineering 0 Civil Engineering OU Shop Superintendent D Auto Engineering Fi O Electrical Engineering ) High School in 2 years NR ditt tititinatachsnirnanded debeiebaandahae date tinperlancedtentdonddateundacviwmniene a cighdiasidcnbbnndndinedeatiddnianhaal ET i bacncancal ORs ccttccinnnncticninnnctionnasing BE A MOTION PICTURE OPERATOR 6 ros Senne TALKING EQUIPMENT | rs | r (? thts Seay “and pleasant work. Bi ; demand for ‘onined operators. MOTION PICTURE OPERATORS SCHOOL Detroit, Mich. AVIATION Information Send us your name and address for full information re- garding the Aviation and Airplane business. Find out about the many great opportunities now open and hew 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. 1363 3601 Michigan Ave. CHICAGO 59 Sproat St. FREE MARCH,

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? 7 d 1. e i- e d y le _ —_—= aa o Marcu, 1930 Build it with a MAYDOLE POPULAR SCIENCE MONTHLY Please send a free copy of Pocket Handbook 23-B containing many useful tables and handy information. ee ee | ris] This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. Telephone tables, ship models, gar- den trellises, chicken coops—any job js easier with a Maydole. Take one in your hand and swing it, you'll understand why. It has a re- markable ‘“‘hang”’ that has never been equalled, face and sides have just the right crown to prevent marring the work and the claws will pull the smallest brad or largest nail without slipping. If you take pride in your tools and the work you do, you’ll want these Maydoles in your set. Your dealer carries them, ask him to show them to you. a HAMM ile ydo he ot ten The David Maydole Hammer Co..Norwich. NY 3597 165

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166 POPULAR SCIENCE MONTHLY Meth Sense! Successor to “BLIND MAN'S BUFF” Trt van Tycos fe or the Home Automobile Tire Manufacturers Frooe Office Thermometers Use results in cooking. mcmne: The Sixth Sense of Industry Freoe Wall Thermometers To help you to maintain a temperature in your house conducive to good health. Feces Quality Compasses Sece Instruments the “Sixth Sense” of In- Bees Fever Thermometers dustry unfailingly guard the vulcanization of Siese Sovmegquide millions of Automobile Tires to insure their life Forecasts the weather twenty-four hours ahead and your safety. The variation of a degree of with dependable accuracy. — temperature, or a iy minutes in ow —— of the process would mean tremendous loss to Trece Hygrometer the ph at ave ay An aid in promoting human efficiency hy Treos Bath Thermometers O § Tyeos Home Set a Bake Oven Thermometer, Candy Thermom- : eter, Sugar Meter. ‘ To enabl u to keep the humidity of th ctmoeghere ia your home coteace o¢ oll cise. They have replaced special artisans who years h ago were trained to do this work. They have entirely eliminated “Blind Man’s Bluff” or the | Tycos for the — work which was inevitable when absolute Medical Profession dependence was placed upon the man’s ability to determine just what was right. Fees Sphygmomanometer, Recording, Pocket They are saving labor, eliminating loss through and Office types. spoilage, and insuring uniformity of quality in Tyeos Fever Thermometers. the largest rubber tire manufacturing companies of the world. - Tycos in cAviation TO THE MANUFACTURERS A full line of Aviation Instruments for ships J 8,000 varieties of indicating, recording and controll- and airports. ing instruments are manufactured by the Instrument Companies. If you are in a business in Your dealer will show them to you. which temperature is used in any of its processes, Ask us, on a postal, for booklets on the Yeos line will increase the efficiency of your any of the above. operation. Bulletins on request Informative literature will be sent you on request or one of our engineers will be glad to study your particular problems and make recommendations. Taylor /nstrument Companies Main Office and Factory: ROCHESTER, N.Y., U.S.A. Canadian Plant: Sos Building, Toronto SHORT & MASON, Ltd. Manufacturing Distributors in Great Britain E~ SIXTH ~ SENSE a ~ INDUSTRY cos Temperature [nstruments INDICATING « RECORDING ~ CONTROLLING Marcu, 1939 arcs, I! The First Pneumatic Tire—Invented to Please a Boy (Continued from page 44) The inventions which now require the bulk of pneumatic tires—the automobile, the motor- cycle, and the airplane—were yet to become’ common. After the success of the tricycle, Dunlop made:a larger pair of wheels and fitted: them with his air-filled tires. They were attached to a bicycle frame which had been built at a local shop. On this new machine, Johnnie “scorched” along the roads near Dublin to his heart’s content. When Dunlop tried to interest the. leading. cycle maker of Ireland in his tires, the head of. the company, knowing the wheels were home- made, said they must be “‘rum”’ wheels. “They will beat anything you have made,” Dunlop told him. “That is something I would rather see than hear about,” was his answer. “Come around tomorrow, and we will show you,” Dunlop’s invited. The next day the cycle maker, formerly a professional racer, rede up to the veterinary’s house on a shining new machine of the latest pattern, with trim, hard-rubber “shoestring” tires. Johnnie appeared on his bespattered, ! homemade machine with its bulging, “freak” tubes, and they started down the longest stretch of macadam in Dublin. The racing man bent over his handlebars trying vainly to keep up with the flying Johnnie. When they returned, he was pufling and admitted his defeat. THE racer immediately ordered a pair of the tires for a new bicycle he was building. Soon afterwards, he was riding this machine home to dinner when he rounded a corner at Castle Place at such a clip that the policeman cautioned him for exceeding the speed limit. Soon racers in various parts of the country were asking for pneumatic tires. Dunlop en- gaged an assistant, writing specifications for the tires on the board wall facing the work- man’s bench. Even after the demand for the new tires increased, the public still scoffed. The chief Irish cycling magazine dismissed Dunlop’s invention with: “Pneumatic... sounds like ‘news-room-attic’... bah!” An. Edinburgh rubber firm declined to fill Dun- lop’s order for rubber tubes because it did not want “‘to become a party to one of the most: impractical ideas ever proposed.” To advertise his invention, Dunlop went about giving demonstrations, rolling and drop- ping the tires to show how they would absorb vibration and withstand shocks. At last he obtained financial backing and a company was formed. Because of their many wrappings of can- vas and rubber, the first Dunlop tires were called “mummies.” When they were punctured, the outer canvas jacket had to be cut open with scissors, the tube pulled out and fixed, and the jacket sewed up again. Once when the inventor was taking a vacation near his birthplace in Scotland, he met a dejected cyclist trundling his machine, with a flat tire, along the road. He did not know how to fix the puncture. Dunlop climbed down from his buggy and did it for him. When the cyclist learned who his helper was, he declared he would keep that tire always as a souvenir. In later years, Dunlop, unfortunate in busi- ness dealings, felt he never received full credit or financial reward-for his invention. How- ever, when he died in 1921, at the age of eighty- two, millions of people were enjoying comforts which they would have lacked but for this man whom a member of Parliament called “that plodding and success-deserving Scot.” ee Plas ter s Cr car ne!

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1939 Oor- ae oe ee > (ee eae yarcu, 1930 POPULAR SCIENCE MONTHLY 167 There’s Many a Place for Plastic Wood Plastic Wood placed in a cas- ter socket will hold the loose caster fast and firm. Cracks around the baseboard can be quickly and perma- nently filled with Plastic Wood. Before replacing screws fill the old holes with Plastic Wood to hold the screws fast. Handles Hardens Like Into Putty Wood When hard it is waterproof and grease- proof, takes paint, lacquer or varnish perfectly, can be worked with tools, and adheres lastingly to any base. Plastic Wood is an invaluable aid to the upkeep of the home. Plastic Wood is the ideal filler for replacing bathroom fixtures and loose tiles. Shelving and cabinets can be made insect proof and dust proof by sealing any cracks with Plastic Wood. Plastic Wood is carried by Hardware and Paint Stores, and comes in handy house- hold tubes at 25 cents; % lb. cans at 35 cents and 1 Ib. cans at $1.00. Plastic Wood Solvent, to soften or to thin Plastic Wood and to clean the hands or tools after us- ing, is sold in 25-cent and 50-cent cans. For wood rot use Plastic Wood and save expensive re- placements. Many a toy accident can be permanently repaired with Plastic Wood. For loose rungs, gouged or chipped furniture, Plastic Wood is a repair kit in itself. Manufactured by Addison-Leslie Company, 325 Bolivar Street, Canton, Mass. REG, VU. S. PAT. OFF,

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POPULAR SCIENCE MONTHLY LOOK FOR ALUMINUM AND YOU WILL FIND KNIFE-EDGEI SELECTIVITY, CLEARER TONE A vast majority of radio engineers use Alcoa Aluminum for variable condenser blades, because the blades them- selves must be perfectly flat, must also be perfectly uni- form in thickness—they must not vary the width of a split hair, if you are to get knife-edge selectivity, clear, sweet tone. Not only must the blades of the condenser be made flat and perfectly uniform in thickness, they must remain so throughout the life of the radio. Alcoa Aluminum variable condenser blades always remain true to shape. That’s why so many radio engineers insist on using them. Weighing only % as much as other metals commonly used in condenser blades, Alcoa Aluminum throws less weight on the tuning supports. Mechanically your radio is easier @ ALCOA ALUMINUM. and smoother to tune. The lightness and strength of Alcoa Aluminum also insures that the condensers will not be thrown out of their fine adjustment in shipment. In your home the set will give the same clear reception that it gave when tested at the factory. Of all the materials used in set construction, Alcoa Alumi- 7 num has the highest electrical conductivity, weight for weight. It makes possible the effective electrical circuits 7 now demanded. Look for Alcoa Aluminum variable condenser blades in the set you buy—also Alcoa Aluminum foil condensers, shielding, wire and other parts. It is your assurance that the manufacturer has selected the most efficient material. ALUMINUM COMPANY of AMERICA; 2496. Oliver Building, PITTSBURGH, PA. Offices in 19 Principal American Cities. CTC VT VV VVC VEE © This seal on a advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. Se pge 8. R. R. DONNELLEY & SONS CO.. CHICAGO ‘]