Popular Science Monthly 1929-12: Vol 115 Iss 6

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NOV 12 December 1929 25 cents MONTHLY Founded 1872 _ Aviation ~Radio ~Automobiles ~Home Buildin j ' New Ideas: Engineering-Exploration™” TheHomeWorkshop !

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eeepc What Electric Power is doing for you Db? you ever wonder what these multitudes of whirring motors are doing for you— your job, your home, your children? The answer is clear. They are weaving the fabric of a richer civilization. They are making new wealth, new comfort, new leisure, in which everybody shares. For example, since 1914, the cost of raw materials used by the General Electric Company has increased nearly 40 per cent. But the intelli- gent use of 145 per cent more electric current has so helped to increase the pro- duction per worker that it has been possible to more than double the average wages. At the same time, the average price of the finished products, excepting lamps has been increased by less than 20 per cent. Prices for the greatly improved MAZDA lamps are 48 per cent less than in 1914. Scores of other industries can show equally amazing gains—human gains, of health, wealth, and happiness—as a result of their increased use of electric power. Because electricity is used in the making of General Electric products and appliances, the workman who makes them is better paid, and the products themselves are better, more dependable, more economical in use. On thousands of these products, from the little motor that runs your electric refrigerator to the big one that powers your commuting train, the General Electric monogram represents the highest standard of electrical correctness and dependability. 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 GENERAL ELECTRIC

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Se DeceMBER, 1929 P POPULAR SCIENCE MONTHLY CORONA for CHRISTMAS PIPAAIA IAI IAAI AAAI AAAI AIA AAI AAAI A AAA IAAI A AAAI ASIA ASI ASA SAA AISI SASSI SI SIS SI AAA AA AAA AA AA AAI IIA OO tooo CK A AO CC a a A a A A IIa I PIII III IIA IIIA IIISIICSISSISICSICSISIS III IIIS III II ISI IIS SIS SIS ISIS SII ISAACS IIA IIA IIIA I IAI IAAI I III IDI IIIA III III III IIIA IIA IS IAI AISIIAIAIIISAISIAAA AN The best fun in the world is OU know, quite a lot of people make good with just brains. Successful creative work and high scholastic standing are just as excit- ing and gratifying as winning in other sports. In the end it gets down to a competition in brains and noth- ing else. Brain muscles keep on winning after body muscles have softened. The point is that in brain sports, Corona is as useful as matched golf clubs or a well-strung racket are in other sports. Of course, in college, you can hardly make the grade with- out a typewriter. Typewritten work invariably gets higher marks. Written work often gets no marks at all simply because no one can read it. In any form of literary competition, Corona is as necessary as running shoes to a runner or sharp skates to a skater. As a matter of fact, every member of the family needs Corona. Mother’s club work, for example—papers to be read, resolutions, committee reports, publicity work; also the conduct of winning with brains household affairs. Many times a year it would be a help to Dad when he has night work to do—speeches, arti- cles for technical papers, an occa- sional important letter. It’s up to you to let the family knowthat yourbig Christmas need this year is a Corona. Families are often hazy about presents without a little guidance. It might work just to mail this advertisement to one of your par- ents. A subtle hint like that is some- We show here attractive Christmas gift times as effective as coming out and asking. The family will thank you for getting Corona into the home. Corona is a great machine. You'll CORONA carton and the regular carrying case. know that the instant you get your fingers on it. Smooth running as a new car, durable as a good reputa- tion, easy to learn, so sturdily simple that it never goes wrong. There are two Corona models: Corona with stand- ard keyboard at $60, and Corona Special with three- row keyboard at $39.50. Attractive carrying case comes with either model. Both are finished in many different colors. Sold by all type- writer dealers and in stationery stores, department stores and specialty gift shops. Deal- ers will be glad to send one on trial and arrange for gradual payment. An allowance will be made on your old typewriter. L C Smith & Corona Typewriters Inc, 51 Madison Ave., New York City.

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POPULAR SCIENCE MONTHLY DEcEMBER, 1929 WHAT IS NEW THIS MONTH Table of Contents for December LEADING ARTICLES | Automobiles A New World Run by Dynamo ; . By Grover C. Mueller 19 Dashboard Spray Puts Out Cigar- Why electric power is causing a second industrial sian Si Sa. te “wee 60 First Victories in the War on Fo _. . By Edwin W. Teale 22 py i lee peeds 63 How science is beating aviation’s chief enemy Used Auto Oil Reclaimed in Tests 64 Oil Wells Drilled in the Ocean ... By George Lee Dowd, Jr. 24 a Marvels of undersea petroleum fields is bn Be o Galen Ganon eee is High Speed Skyways 14 Miles Up =F By Alden P. Armagnac 26 Simple Holder for Valve Pin . 84 hy engineers seek to navigate the uscsneaghinn,” the top of the air Handy Squirt Lubricator . 84 Windshield Gap Closer 84 Why Minds Behave As They Do . 28 Ten Dollars for an Idea 84 Fascinating revelations from the recent International Psychological Congress ye viation Welding—The Silent Builder ; By Robert E. Martin 30 Latest triumphs of the noiseless way to erect skyscrapers New 30-Passenger Plane 40 Keeps Lit Parachute Flare F loating Can Science End Forest Fire Peril? . By Alfred P. Reck 32 for Hour . 40 Menace increases despite work of Forest Service, officials report Test Hazard of Cigarettes Dropped from Plane. 40 The Moon Is Made of Cinders . By Thomas Elway 44 Planes Fly Tied Deastiee 40 New knowledge about our neighbor satellite Queer Tandem Machines Fly . 4l ew Parachute . 41 set : in me oy ‘the inside facts about dotinn eo Six Miles a Minute! 41 cece _ ; ans 8 Latest Air Words j 4] Diamonds—Tiny Skyscrapers Built of Atoms . .By E. E. Free 49 Novel Equipment on New Plane Searching with microscope and X-ray to find how wall grow Models. 41 Measuring Flowing Qualities of A Box of Sounds for the Movies , 51 Liquids for Plane Instruments . 41 How a modern pipe organ produces its effects A Shield from Lightning 42 Ice Anchor for Dirigibles . 42 Fossil Monsters I Have Hunted . By Charles H. Sternberg 56 First Aerial Billboard ._. 42 An expert tells how he bags dinosaurs Air Taxi—20 Cents a Mile 42 Mail Pick-Up in Service 42 SPECIAL FEATURES Making a a mely on ® , . 42 . : _ By Herbert P, New Groun ool for Women . 42 Sane Heten — pa Bleriot’s Plane Placed in Museum. 42 “Gimme a Tip . By Wallace Ames 4 Passenger Transfers from ee Mick in the investment world to Plane . ; . Drops Mail by Parachute . 43 Looking for the Best? ._ By F.G. Pryor 12 Amphibian Has Wheels That Fold 43 Tips from the Popular Science Institute of Standards Largest Land Plane Enters Pas- senger Service. 43 Our Readers Say— is Detac _ Parachute Basket in Back of the Month’s News . By Karl Vooght 52 Fuselage . 43 Timely comment interpreting ‘the latest in science ha pow to Test 66 Editorials .« + « *& ee Airplane and Dirigible Combined in Model . 66 What the New Radio Sets Offer By Alfred P. Lane 70 Palatial Hangar Has Novel Fold- How to decide what receiver to buy ing Doors 69 A Well-Built House Is Cheapest . . By Roger B. Whitman 74 How to save money by ae Al it at the outset En gineerin g Where the New Motor Cars Excel . . By Martin Bunn 76 The Newest Arch Dam . 53 Gus and Joe discuss the latest models Suction Pipe “Stevedores” Un- load Copra Cargoes .. 59 rating a Model Railway System By Frederick Ryder, Jr. 77 ~ Traie dispatching with miniature locomotives and cars — ay Pierces Can- 62 Christmas Cards by od pete Ud . . By John Steinke 80 aa to Have Greatest Arch “ h lid ti ridge ° , S mete way 06 send pusensl Ben ay gree ings Test Steel-Paved Streets . 67 Hints on Heat Treating Steel... . By Henry Simon 90 Volcano’ s Steam Will Heat Hotel Expert advice on hardening tool metal _ s in Hawaii oo December, 1929, Vol. 115, No. 6. Popular og ty oe is a pubiiehed, onth- United States, its possessions, and Canada, $2.50; foreign countries, $3. The Tol fi ARIE rh ge Ry a ag os under the act of Mtarel ns. 1879; additional entry as second-c . Ay Chicago, Illinois. Entered as second-class matter at the Post Office Canada. Printed in U. a) A. Copyright, 1929, by the Popular Departmen stock-sellin, BSelence Publishing Co., Ine. Single copy, 25 cents. Yearly su urer; R. C. Monthly does not underwrite the business methods of the individuals or con- cerns presume them. The use of es Science Monthly articles for emes is never authori Capen, President and Treas- jilsom, Vice-President; A. L. Cole, Vice-President and Secretary.

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DeEcEMBER, 1929 POPULAR SCIENCE MONTHLY Exploration Back to the Stone Age in a Modern Yacht. . 34 Climbing to the Ww orld’s Roof Tops . . 37 Science and Tagely in : the haetie 38 African Rivers May Hold Fortune inIvory . . 63 American Party Fi irst to Scale Alpine Peak... 67 Calls East Indian Siena an Earthly Paradise . . . . 69 Health and Hygiene Nervous Cities. . 52 How Much Do You Maen shen Eyeglasses? ; Bandaging with Silver . . . 60 Mental Disorders Increase in Spring, Tests Show. . . . 67 Laboratory Discoveries Lightning’s Own Fingerprints. . 33 Studying the Apes. . . . . 55 New Evidence That a Is Electric . . 65 Models Furnishing the Bluenose Deck . 86 Sharp Knife Aids in Model Plane Building .. : 102 Toy Woodworking Machines : Model of Darmstadt 7“ Sail Plane... 111 New Colored Pencils Aid i in Ship Model Work . . 132 Nature Nature’s Seed-Sowing Machines . 36 A Fish with Lungs. . . . . 54 Huge “Elephant Ear” Leaf Is 47 Inches Long .. 61 Rattlers’ Den Dy nenieed, het Snakes Survive .. 62 New Devices for the Home Lifts Cap Off Milk Bottle . . 73 Shaped Salad Molds for Bridge Luncheon. 73 Lifts Eggs Out of Water When They Are Done ._. 73 New Electric Range Has No Legs 73 Device Punctures Milk Can for Pouring . 73 Tilting Stand Empties Washtubs 73 Rubber Door Wedge Can't Slip 73 New Processes and Inventions New Hot Water Bag Saves the Skin from Burns . 60 Penny-in-Slot Doorbell ’ Keeps . Hawkers Away . 60 Service Set ee to the Card a 61 4 r \ Round Playing Cards Are the Latest. Cable-Laying Machine Bores un- der Street Revolving Camera Makes Planes Do the Loop . ee Radio Power by Radio Possible? . Radio May Trace Mystery of Bird Migration _ ” One Radio Set Supplies 2, ,000 Headphones . —— in Choosing a New Radio et ; A Handy Radio ‘Trouble Lemp Screen Grid Suppressors Stopping Audio Howls. Limits of Selectivity A B C’s of Radio Unusual Facts and Ideas Painting a World’s Fair with Light New Cloud Atlas to ataaalh Predict Weather... Stars Too Hot to Seo Universal Yardsticks History in Tattoos . “Medicine” for Steel Locomotive, in Endurance Run, Sets Record High Seat for Cestemacs Aids the hoe Salesman Motor Buses Replace Lest of Vermont Trolleys ‘ Young Geologist Unearths —_ of Ancient Whale Beas a “Slaves” Found in Graves Egyptians . Outboard Motor Boat Sem iia the Waves Chemicals Injected Fireproof Lumber ; Intelligence No Guide to _—— Skill, ‘Tests Show Testing the Strength of a Stage Whisper Cathedral Wades —— Dey “Shaving”. Electroscope Finds ent Tube of Radium ; Tribe Has Reupeene That Conant Be Written Steamer Sights een. in ‘Die atlantic Flight Pd ae Indoor Hopscotch Game Played with Marbles i : Quake Relieves Drought nw Old Auto Engine Runs Portable Hay Baler Machine Teaches —— ‘the “Splits” a of Life at " Chilcage 600 illion Years Ago . Seal Hunters Make Record Catch of 40,000 Skins ; Movie “Sets” Shifted by Over- head Railway ‘ Plane Breaks Kite String al Spoils a Record . New Theater Program Can Be Readinthe Dark. . into —_— 61 63 52 60 67 71 72 72 72 72 72 25 52 53 54 54 55 60 60 61 61 61 62 63 63 64 64 65 65 65 65 68 4 Suguete Insect Hunting by Ocean oyagers. . . 68 Bark of a Rare Cinnamon Tree Worth $4,000. . . 68 Long-Burning Fires Hold ‘Endur- ance Records. 69 Auto Balloon-Chasing a New French Sport. 69 Old Church Wears Odd Coat of Scaffolding . . 69 Panama Canal Busy .. . ..-— 69 Water Fleas and Heredity. . . 147 Sunshinein Candy . . . . . 158 For the Home Owner Four Useful Everyday Knots. . 108 A Few Facts about Applyi ing Glue . . 114 Spotlights Brighten a ‘ Caskstmes Tree . . 118 Hints on ee a Paint Brush Skillfully . . . . . 130 Rope Handrail for Incloned Stairs 134 Coconut Converted into Novel Table Lemp... ... «0. 1M Hints for the Mechanic Annealing Large Size Castings .. 92 Sawing to a Curved Line with Cut-Away Hack Saw . 92 Drill Deep Holes in the Lathe . 92 Grinding a Reamer... 92 Reversed File May Improve hens formance of Machine. 92 Loosen Chuck Jaws in Finishing Thin Ring. . : 92 Grooved Set Screw Makes Tap for Cleaning Holes. 92 Pocket Mirror a Handy Tool. . 92 Ideas for the Handy Man One Man Who Has Every Tool a Woodworker Needs ._. 82 Preparing and Painting Conese oors. . . . 88 How to Operate a Jig San . Soy Play Screen for Children . . . 98 Embossed Leather Bill Fold . . 100 Semiautomatic Box Serves Ciga- rettes One by One . . . . 107 Support for Slender Work . . 109 — for the Home Work- “ 11 Easily Constructed Modernistic Desk .. . 117 Space-Saving Shoe aa Polish Case . . Embellished Coppet Letter Open- ers. . . 120 Building Pusinies into Unesed Doorways .. . . 122 Ivory in the Home Workshop . 125 Laundry Case with Removable ae 126 Simplified Electric ‘Toaster Built at Low Cost. . . 128 Small Clock Case for Holding « a Watch... 129 Caring for an Oilstone iw 2 } Guide for Drilling Glass . . . 136

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POPULAR SCIENCE MONTHLY DEcEMBER, 1929

“FISCAL—-MANAGE D” INVESTMENT TRUSTS

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A definite program for getting ahead financially will be found on page four of this issue. One Cent a Day Brings $100 a Month

OVER 135,000 PERSONS HAVE TAKEN AD- VANTAGE OF LIBERAL INSURANCE OFFER. POLICY SENT FREE FOR INSPECTION. Kansas City, Mo.—Accident insurance at a cost of one cent a day is being featured in a policy issued by the National Protective Insurance Association. The benefits are $100 a month for 12 months— $1,000 to $1,500 at death. The premium is only $3.65 a year or exactly one cent a day. Over 135,000 paid policies of this type are already in force. Men, women and children ten years of age or over are eligible. No medical examination is required. This may be carried in addition to insurance in any other company. SEND NO MONEY To secure 10 days’ free inspection of policy, send no | just send Name, Age, Address, Bene- ficiary’s Name and Relationship to National Protec- tive Insurance Association, 1123 Scarritt Bldg., Kansas City, Mo. After reading the policy you may either return it without obligation or send $3.65 to put policy in force for a whole year—365 days. ‘ OU’RE in Wall Street... tell me something good. I’ve got $500 and I want to run it up to around $1,500 within the next two or three months. What’ll I buy?” In such words was the Financial Editor of PopuLaR SCIENCE MONTHLY recently greeted. Some readers may see a tincture of humor in this modest ambition to triple a sum of money in three months. Hardly a day passes, how- ever, without just such a question being put seriously to practically every man whose occu- pation is in the financial field. How should such a question be answered? First, let’s see how the “experts” judge the stock market. The following was published in the New York Sun during September: “The investor or speculator who reads the advice obtained from commission house letter writers will find enough contradiction in today’s assortment to make his head swim. About as many assert confidently that the next trend will be upward as are positive that the market is going lower.” Stock brokers desire to supply their cus- tomers with dependable information. They maintain staffs of trained statisticians and analysts; these men have access to every con- ceivable form of official data; their sole occupa- tion is to study trends and values. And yet— not only occasionally, but almost invariably there is a wide divergence of opinion among stock market experts. Higgledy-Piggledy Omitting the names of their authors, we quote below excerpts from brokers’ market letters which were published the day that the above mentioned item appeared in the Sun. Each quotation represents an expert opinion. Read them in order and note the contrast. “Look for gradual drift to lower levels.’”” (The market) “ gave impressive evidence of its ability to work higher.” “Correction has now gone far enough to warrant moderately bullish attitude on high grade stocks.” “We suggest the lightening of accounts.’ “The action of the market Friday gave strong indications that readjustment of its technical position has been practically com- pleted.” “ This week’s increase in brokers’ loans is dis- appointing.” ’ “Stocks were meeting with strong support.” “We see no real check in the selling move- ment.” “After a period of irregularity the upward trend will be resumed.” “The preponderant trend for the immediate future will be downward.” (The market) “Will shortly resume its former buoyancy.” “The market as a rule should be liquidated on rallies.” October 3 witnessed one of the most per- ndicular declines in the history of the New York Stock Exchange. During the previous day prices were advancing. The following opinions as to the immediate future trend appeared the same day that the decline was in progress: “The lows have been temporarily reached.” “A secondary reaction is coming after the present forward thrust.” “The market acts as though it were trying to go up.” “Stocks will be offered for sale on every bulge.” “The current rally in the market will con- tinue further.” , ’

“GIMMIE A TIP”. By WALLACE AMES, Financial Editor (We are) “not inclined to follow the current rally as yet.” Just the day before such a drastic decline as occurred October 3 there was a wide conflict of opinion among experts as to what was going to happen and many advisers were taken | completely by surprise, as the above quo- tations show.

Vague-ries A common characteristic of brokerage ad- vice is its vagueness... probably the result of doubt or lack of conviction on the broker’s part as to future trends. Asa vague suggestion, “Maintain a trading position” is a popular favorite. And what, for example, do you get from the following quotations which were also taken from opinions published in the Sun. What action would these advices suggest to you? | “Seek out new favorites.” (We want to see) “‘more evidence of vigorous buying in stocks of investment calibre.” “ As has been the case for the last six months, the market problem continues to be one of proper selection.” “‘Breaks in many directions would still sug- gest the probability of further correction.” (We are) “in favor of a more inviting market for trading commitments.” “Special development will probably play a larger part in the market of the immediate future.” | It would seem that such opinions as quoted represent groping for a clue as to the immediate future trend rather than an appraisal of intrin- sic values. And that, by the way, is one dif- | ference between speculating and investing. The speculator is guided largely°by what he thinks, or what someone else thinks is going to happen; he would buy a stock of no value whatever, if convinced he could sell it at a profit. The investor, on the other hand, while harboring a desire to see his securities go up is actuated in his selections by known values. The goose-bone prophet who predicts rain every day will sooner or later be right. The professional stock market advisor, who is passing out opinions all the time is bound to be right part of the time. But where does that leave you? A prominent figure created considerable stir early in August of 1929 by predicting a 50- or 60-point break in stock market averages. Per- haps the September decline was severe enough so that we may regard his prediction as realized in a practical sense. But even the September decline only wiped out about 65% of the ad- vance that occurred during August in the wake of the bearish forecast. In a speculative effort there is a deal of difference between thinking and acting. <A thousand experts may think the market is going up. Simultaneously, another thousand may think it is going down. But when you have $500, $1,000 or some other definite sum with which to take a market whirl, you can’t just “think” about securities... you must take some action. Seeking speculative advice leaves you confused and confounded .. . you finally act in the dark. Note we said speculative advice, which is a different thing than invest- ment advice. It is so easy to forget that either investing or speculating in securities is a forward-looking process. People confuse reflection with vision. They recall the former prices of Atchison, American Tel. & Tel., General Electric and other so called “blue chips.’’. .. They figure out the profits that might (Continued on page 5) ——

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en. DeEcEMBER, 1929 POPULAR SCIENCE MONTHLY INTIMATE GLIMPSES OF FIDELITY BOND HOLDERS Among the thousands of Fidelity Bond Holders are churches, lodges, trustees and organizations having funds which must be in- vested wisely. Investments are made only after securities are sub- jected to closest scrutiny. Rate of return is second in importance to safety of principal. Since Fidelity Bonds offer a high rate of return and the safety of principal is ab- solutely assured by the Fidelity guarantee of payment at maturity, investments in these securities by such organizations are numerous. of Als. Je The individual investor can well issues sent, follow the practice of seasoned in- without ob- vestors. Fidelity Bonds are con- ligation, up- servative first mortgages on new on request. income producing real estate. They are priced to yield 6%. I BOND * MORTGAGE ry J.U. MENTEER . Prov INCORPORATED 1913 660Chemical Building, St. Louis 1188 New York Life Bldg., Chicago 378 Colorado Nat’l Bank Bldg., Denver N649P107 The Unwritten History Of Your Baby The most fateful part of any book is in the earlier pages. Your baby cannot write the early chapters of his own history. You must write them. Will your baby go to college ?—You must decide. Will your baby enter manhood or womanhood with advantages or handicaps?—You must say. Let us tell you about a simple, common sense plan whereby almost any aim or hope you may treasure for your baby can berreal- ized by the systematic investment of small sums, plus the magic of compound interest. If you will follow the plan we will UN- CONDITIONALLY GUARANTEE the funds. Write today for full details and for our latest financial circular, showing resources of more than $28,000,000. | INVESTORS SYNDICATE | ———"tablished 1996: INVESTORS SYNDICATE BUILDING MINNEAPOLIS, MINN. Offices in 51 Principal Cities “GIMMIE A TIP” (Continued from page 4) have been made. Then they indulge in a few mental contortions: “If I buy this or that, and if it goes up like so and so to such and such a price ... presto... I have tripled my money.” You can always figure out how you might have made a killing, but figuring ahead is not simple . . . free advice notwithstanding. The statistician of a prominent Stock Ex- change firm designed a series of charts which proved that a certain stock was a good pur- chase around 112, at which price it was then selling. The stock did reach a high point of 135 during 1929... but it’s now around 50. If you could have called the turn you could have made money on this statistician’s advice. But when experts disagree so violently as to the trend of the whole market, what chance have you to call the turn on an individual stock? And where would you have been had you bought this particular stock at 112 to hold for investment? You would have been in for the long pull . . . with emphasis on the long pull. There lies before us a copy of a financial daily. A front-page article bears this caption: “Stay Out, Advice Given by Brokers. Most Think the Market too Uncertain to Warrant New Commitments.” In the light of the rest that we have written this comes under the classification of sound advice. But the article was printed October 1—after the September decline—a bit too late to save the profits of most speculators who depend on professional opinion. Following are eight stocks, one pair repre- senting each of four industries. In each case one of the pair went up during September; the other registered a decline. The figures show the changes in price which took place between August 31 and September 30, 1929. Allied Chemical, declined 35 points Commercial Solvents, advanced 12414 points General Foods, declined 634 points National Biscuit, advanced 5% points Standard Oil (Cal.), declined 234 points Standard Oil (N. J.), advanced 2 points Consolidated Gas, declined 18 points Columbia Gas and Elec., advanced 24% . points In the above cases the speculator who thought chemicals were good won if he picked Com- mercial Solvents; he lost if he chose Allied Chemical. If he favored the utilities he won on Columbia or lost on Consolidated. This is the way a tip usually works out: Mr. A. isadvised to buy So-and-So and is primed as to what is going to happen in that stock. He watches it; it goes up; then he buys near the top and watches the price decline. More people buy stocks after they have gone up than before. It is a peculiar quirk of human nature. Another characteristic of the human race is to like to pass along “inside dope.” If you could trace to its origin any one of the tips you get you would be surprised at its long string of ancestry and the doubtful character of its parents. Putting all these facts and illustrations to- gether brings us to only one conclusion. Fol- lowing speculative advice is a hazardous un- dertaking—about as hazardous as speculating in the dark. But what to do? Invest—don’t speculate. Buy known values—not hunches. Put your money in something you are willing to keep and you'll have more money in the end. The investment trust is one answer to the desires of the man who wants to participate in stock profits. The average investment trust invests in stocks and bonds—a wide diversifi- cation of each—all selected on their intrinsic merits and none chosen on tips. Investment trusts frequently sell their holdings and make profits, in which their shareholders participate. But they buy and sell on an investment basis— instead of being guided by speculative im- pulses. (Continued on page 6) Retire in l 5 YEAS on your Present living Budget by investing in safe 642% First Mortgage Bonds Follow the definite plan given in the new edition of this famous k, and your financial independence is won. The plan works just as surely whether you are now earning $1,000 or $100,000 a year. The way is certain—each step plainly in- dicated and absolutely safe—independent of luck, business genius or speculation. Every fact has been harvested out of the 48 years’ experience of Cochran & McCluer in the first mortgage investment banking business. The plan is so simple any one can under- stand it—so definite any one can follow it—and so certain no one can fail. In addition to the Financial Independ- ence Plan and the unique budget sched- ule, the book gives suggestions that en- able you to enjoy more of the good things of life, both while building your inde- pendent fortune and after you have at- tained it. We invite the most skeptical to read this lain, straightforward, interesting book. hone, call or send coupon. We employ no salesmen, therefore none will call. MAIL THIS FOR [NEW EDITION | 1% f Cochran & McCluer Co, Psuiz} } } 46 N. Dearborn St., Chicago 4 t Please send me, without obligation, ! a copy of the new edition of your! i. book, “How to Retire in ‘ 15 Years.” this Street. City State. ee eeeeeeseeeeweaead Cochran &M‘Cluer Co, Established 1881—Never a loss to any investor 46 North Dearborn St., Chicago, Ill. H.SmiruCo. (INCORPORATED) Investment Securities—F ounded 1873 Smith Bldg., Washington, D. C. Branch Offices in Other Cities * d In two-tone Artcraft (looks Bin er like leather—lasts forever) Geo with the name of the maga- lar zine stamped in gold on — = cover. This binder will hold lence six copies of the magazine, Monthly and new copies can be slipped Price $200 as easily as inserting a letter Postage Prepaid in an envelope. Poputar Science Pusiisuinc Co. 381 Fourth Avenue New York City

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at its best... in a pipe IN’S preference for a man’s smoke —the pipe—is plenty positive. But do you know why? We'll tell you. It’s a triple reason. First, pipe tobacco’s different—for instance, Edgeworth. Second, tobacco smolders like it should in a pipe—completely, all of it. And third, these mean you get more satisfaction—greater relish of the good old savory burley, soothing fullness of rich smoke. There’s even a fourth reason: you like good company. The pipe-smoking broth- erhood is that. Its members are thinkers and leaders. Tobacco’s at its best in a pipe. It gets a chance to be itself there—to loosen up as it comes to life, to expand and take in air and glow. Only the choicest leaves get that chance, moreover, for pipes tell the truth about tobacco. Choice leaves, choice blends, and mighty careful han- dling. Edgeworth comes up through eleven distinct processes before we're willing to pass it on to you. If you’ve been missing all this, that’s your misfortune. If you keep on, it’s your fault—for we’re waiting to send you your first pipefuls of Edgeworth. See the cou- pon? Fill it out, get a good pipe and the postman will bring you a neat little glad- to-meet-you packet of good old Edgeworth. Edgeworth is a combination of good tobaccos—selected carefully and blended especially for pipe-smoking. Its quality and flavor never change. Buy it any- where in two forms—“‘Edgeworth Ready Rubbed” and “Edgeworth Plug Slice.’’ All sizes—15¢ pocket package to pound humidor tin. EDGEWORTH LARUS & BRO. CO., Richmond, Va. I'll try your Edgeworth. And I’ll try it in a good pipe. N Street__ Town and state Now let the Edgeworth come! POPULAR SCIENCE MONTHLY ‘**GIMMIE A TIP” (Continued from page 5) To Help You Get Ahead T= Booklets listed below will help every family in laying out a financial plan. They will be sent on request. ‘*How to Buildan Independent Income”’ is the title of a new booklet by the F. H. Smith Company which explains conclusively how pegs of moderate means may obtain financial = May be obtained by addressing the ome office of The F. H. Smith Company, Smith Building, Washington, D. C. The House Behind the Bonds reminds the investor of the importance, not only of studying the investment, but of checking up the banker who offers it. Address: Fidelity Bond & Mort- gage Co., 1188 New York Life Building, Chi- cago, Ill. How to Retire in Fifteen Years is the story | of a safe, sure and definite method of establish- ing an estate and building an independent in- come which will support you the rest of your life on the basis of your present living budget. Write for the booklet to Cochran & McCluer Company, 46 North Dearborn St., Chicago, Ill. How toGet the Things You Want tells how you can wse insurance as an active part of your ogee 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 lan will bring you financial —— rite for this booklet to Investors Syndicate, 100 North Seventh Street, Minneapolis, Minn. Prize Investment List Comparisons: This folder compares the record of Financial Investin Co., of New York, Ltd., with the results sditevel during the past four years by 14 prize-winning investment recommendations. It shows how Financial Investing shares gained 59% in value and returned an average of 13.35% to investors. For a copy write The Fiscal Securities Corpora- tion, Room 2808, 48 Wall Street, New York. Statement of Ownership, Management, Circulation. etc., uired by the Act o Cena of August 24, 19123 of Popular Science Monthly, published monthly at New York, N. Y., for October 1, 1929, State of New York, County of New York, ss. Before me, a notary public in and for the State and county aforesaid, personaily ap- peared O. B. Capen, who, having m duly sworn according to law, deposes and says that he is the Business Manager of Popular Science Monthly and that the fol- lowing is, to the best of his knowledge and belief, a true statement of the ownership, management, etc., of the aforesaid publication for the date shown in the above caption, requi by the Act_of August 24, 1912, embodied in Section 411, Postal Laws and Regulations, printed on the reverse of this form to wit: 1. That the names and addresses of the publisher, editor, ma editor, and business managers are Publisher, Popular Science Publishing Co., Inc., 381 Fourth Avenue, New York, N. Y., Editor, Hoke, 381 Fourth Avenue, New ork, Managing Editor, Avenue, New York, , me Capen, 381 Fourth Avenue, New York, N. . That the owners are: Popular Science Publishing Company, Inc., 381 Fourth Avenue, New York, N. Y. Stockholders of Popular Science Publishing Company, Inc., Henry J. Fisher, 82 Beaver St., New York, N. Y.; Oliver B Capen, 381 Fourth Avenue, New York, N. Y.; Robert Cade Wilson, 683 Springfield Avenue, Summit, N. J.: Ada B. Wilson, 683 ym Avenue, Summit, N. J., A. L. Cole, 381 Fourth Avenue, New York, N. Y.; John Nichols, 381 Fourth Ave., New York, N. Y. 3. That the known bondholders, mortgages and other security holders owning or holding 1 per cent or more of the total amount of bonds, mortgages, or other securities are: none. 4. That the two paragraphs next above iving the names of the owners, stockholders and secur- fey holders, if any, contain not gnly the list of stock- holders and security holders as they appear upon the books of the company, but also, in cases where the stockholder or security holder appears upon the books of the company as trustee or in any other fiduciary rela- tion, the name of the person or corporation for whom such trustee is acting, is given: also that the said two paragraphs contain statements embracing affiant's full knowledge and belief as to the circumstances and con- ditions under which stockholders and security holders who do not appear upon the books of the company as trustees, hold stock and securities in a capacity other than that of a bona fide owner, and this affiant has no reason to believe that any other person, association, or corporation has any interest direct or indirect in the said stock, bonds, or other securities than as so stated by him. (Signed) O. B. Capen, Business M er Sworn to and subscribed before me this oath day of September, 1929. Esther Eyi, Notary Public, Kings County. Clerk’s No. 37 Registry oo ae New York County Clerk’s No. 256, aes: No. 0- > (Seal) My Commission expires March 30, 1930. | DECEMBER, 1929 Every Handy Man needs SMOOTHON ND. 1 MOOTH-ON No. 1 hardens like iron and ex- pands in doing so to make cracked, open or loose parts everlastingly tight. Don’t pay any professional fixer a big price to make such repairs. With Smooth-On No. 1, you yourself can do a perfect job for a few cents and usually in a few minutes. Get the Smooth-On habit and you will quickly find that it keeps many dollars in your own pocket. Try it on the following and see for yourself: IN THE HOME Stopping leaks in steam, water, gas, oil or stove pipes, mending cracks, * breaks or leaks in furnaces and boil- ers, radiators, tanks, sinks, pots and pails, making loose handles tight on umbrellas, knives, hammers, brushes, drawers, etc., tightening loose screws, hooks, locks, door knobs, etc. ON THE AUTOMOBILE Making cracked water jackets and pumps good as new, stopping leaks in radiator, hose connections, gas tank and gas, oil and exhaust lines, making a fume-proof joint between exhaust pipe and tonneau heater, tightening loose headlight posts, keep- ing grease cups, hub caps and nuts from loosening and falling off, etc. To get perfect re- sults, write to us for and use the Smooth-On Repair Book. Free if you return the coupon. Get Smooth-On No. r in 7 0%., I-lb. or 5-lb. tins at any hardware store or if necessary, direct from us. Smooth-On Mfg. Co. Dept. 58, 574 Communipaw Ave. JERSEY CITY, N. J. Kony Doit with SMOOTHON SMOOTH-ON MFG. CO., Dept. 58. 574 Communipaw Ave., Jersey City, N. J. Please send the free Smooth-On Repair Book. Write for Return this coupon for a FREE copy of Booklet

Page 9

-PR DeceMBER, 1929 Distinguished by NATURAL POPULAR SCIENCE MONTHLY ODUCT O F GENERAL TON e > Day-Fan radio engineers completed a high achievement in designing the splendid sets which dealers are now demonstrating. General Motors Corporation, entering the field of radio through the purchase of Day- Fan Electric Co., now sponsors the offer of these sets to you. The present development of Day-Fan Radio is a “product of General Motors.” A significant endorsement of the quality built into these receivers! The performance of the new Day-Fan Radio Above: Nine-tube set with two 245 tubes in push-pull —units accurately matched throughout —$225, less tubes. There is a console as low as $169.50; table model at $115. (Slightly higher in far west.) MOTORS is marked by a brilliant natural tone— deeply and enduringly satisfying. Respons- iveness is another characteristic—the result of sensitiveness, effective power delivery, and sharp selectivity. Each Day-Fan model is built to a single high standard of quality. There is but one chassis for the standard-tube models, and one chassis for the screen-grid tubes. Select any Day-Fan set with the assurance of en- joying Day-Fan Performance. Day-Fan Screen-grid Radio is engineered to employ the new tubes to best advantage. Has three screen-grid tubes and power detector tube, with two 245’s in push-pull. It delivers all tones with remarkable fidelity, and there has been no sacrifice of selectivity. Model 93, $189.50, Model 94, $240. DAY-FAN ELECTRIC CO. 1712 Wisconsin Blvd., Dayton, Ohio Please send me more information on'Day-Fan Radio. r1S] This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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DECEMBER, 1929

8 POPULAR SCIENCE MONTHLY Guaranteed Advertisement Automobiles and Accessories Page Razors, Toilet Articles, Etc. Page Radio Apparatus Page | mt So Shia sass ce 6s 160 Lambert Pharmacal Company............ 15 Aerovox Wireless Corp................+.- 130 omy he S Cinesesacion.. RVers 79 Ne cari aeieescdiecbine ee 128 Benjamin Electric xa Co.. 131 National . ee 17 Cunningham Co., E. T. ne 132 nee Corporation of America, The. 111 Watches and Jewelry Day-Fan Electric Co............ sti 7 ws dikcatwapeesecteen cap 85 is Oe 66 anedcd atmo ig memes 132 Building M \ gubies Corp... Mash esnapes snesans escenes 116 seuenenenand ait, Co........ 131 aterials tis Bros ERS ee ert eee 126 mmarlund-Roberts Inc. 132 wslcing Stat Studebaker Watch Company.............. 118 Midwest RadioCorp.................... 157 Celotex Com a Pee ee ea ngs 64 camenc ces oan 114 National Carbon Co., Inc................. 87-159 Lewis Mfg. eee 128 Radio-Victor Corporation of America...... 81 Masonite Corporation.................-. 13 Educational ee PER e eee eee 130 Boo oo. dik og: 6c 0 ard eb kewego ned ks , Bliss Biectrical School ere Shs ckcd saath oa dite Aviation Rg ae ee 1 Bogue, Rs caéo0s04.08608s ; Clarkson Pub. EE CAE RROS 16 Chicago Technical College American School of Aviation.............. 153 NE SE ere ee 143. Columbian Correspondence Gop. ery 136 Aviation Inst. of U.S. A.. Stee ee eee 136 Feuchtinger, Prof. E...................-. 154 Cooke Electrical School, L.L............. 153 Dayton School of Aviation, The... ........ 155 McGraw-Hill Book, Co................... 154 Coyne Electrical School......... -....... 133 [Lincoln Airplane School. ...............-. 146 Model Ai: Book Publishers. 126 ag Sthedt of Lettering......... > 136 Pacific Technical University.............. 144 Nelson & ieee civecscteess 9 Dobe, Fred W................ -. 145 Universal Aviation Schools............... 154 Science News-Letter.................0008 150 Federal ‘School of Illustrating 139 Von Hoffmann Aircraft School............ 131 Swedenborg Foundation, Inc.............. 142 wey! Lpnmneeries een ot a eee = s T irst wanan Conserv. 0 usic. nah i eae i Things to Make NS EEE EIT E porting Goods and Toys Funk & Wagnalls Co.............. Oe PLE ere American Chime Clock Co..............+. 126 High School Home Study Bureau.......... American Flyer Mfg. Co.. eaves Craftsman Wood Service................- 112 Institute of Applied Science.............. Automatic Rubber Co.... OO rere 155 International Correspondence Schools... . .134-140 Clinton Toy Corp...... Ideal Aeroplane & Supply Co., Inc......... 120 La Salle Extension University. . . .144-152-158 Crosman Arms Co. Midland Model Works................+:. 118 Lederer School of Drawing............... 142. Gilbert Co., The A. <. Miniature Ship Models, Inc .............. 108 McCarrie School of Mechanical Dentistry. . 142 Hohner, Inc., aia ees ct aso0 cede eure t Woodworking Co.................+. 116 McSweeney Elec. School.................. 150 Kingsbury Mfg. Co........... 129 ca dueceeseceteseeeee 110 Motor Institute of Amer................. 138 Lionel Corporation, The.. ; 105 Model Ship Pe inc ¢étcceeencoes 132 National Automotive School.............. 138 Meccano Co., Imc............. - 97 anes — ag wi 114 I 665. 6 a oa eceand eee 121 Investments Speedo Mfg. Co...............e 130 Sesicen, 0 RGok tee oo, SRawewchandnen : idelit ortgage Co............. ° ‘ ‘ Fiscal Becurities Geops The. . Se Pee 4 P opular Science Industrial Equipment a ecco sk cbooesees 5 Chi s G w National Protective Insurance Assn....... 4 G U A RA NTEE i cago Stock Gear Works............... 126 Smith Company, The F. H................ 5 orton Com icnneiee 6% tent e cece eeee 11 Taylor Instrument Companies............ 117 Tools and Shop Equipment © WG ES rr re 110 Ma-Com Taal Cor... .cccsccccccscccccccce 127 P. t ie ea 114 7 atent Attorneys Atkins & Srrk. MN AG 5: hednck nia baka as POPULAR SCIENCE Dioterieh, Abert E oe gic tterevesonns 14s I CMTE Mins occ ccccsetcccccccese vans a PPR 1 Bridgeport Hdwe. Mfg. Co., The.......... 106 MONTHLY guarantees every Fisher Mfg. Company, Adam............. 150 Brown & Sharpe Mfg. Co................. 93 article of merchandise adver- Gottlieb, Edward...........--..000000000 148 oy Si = tised in its columns. Readers Greene, \_SSPPREEEE SS eeeseaeneaaes 150 a ty NE b66s6s neeceenese , s nventors TCT CO Te 1 Disston & Sons, Inc., Henry.............. 89 who buy products advertised dco nasccncacserenns 150 facturing Co.............++++- 110 in POPULAR SCIENCE Lancaster & Allwine..................-.- 148 Goretacr 605i chap wesscnaves iis MONTHLY may expect them McCathran, NS Sas srorelasncineiandarsioa 148 nc cbbees¢sccccsccecesee s ; i "Brien, re ere 147 II SER GD, 0 8 oc ccc cv cccccceces 118 to F sage one mte d satisfaction Randolph & Company.................... 151 So. ioc ccscenwweses cece 125 under normal and proper use. SS gh emer 150 ooh kc seccehssen inne pees : a3 Tools, Radio Apparatus, Oil ton & Anderson.............. badd cas Burners and Refrigerators ad- Ne og! my OR = vertised in POPULAR SCIENCE Hardware Supplies a el ETE AE 112-130 MONTHLY have been tested or Seomiote: pCa Ameri ee 0, The: seseecceees = Nicholson Did datteheceduaen decks 119 s ‘ sein Mfg. Co. o mbies, The. .....620 I I GM og ccc cc ccccecccces 107 —, by pr ao Johnson & Son, S. C.. ppancneeas 83 6 ins ewes viwnceces oe 126 lence nstitute of Standards a eee 102 Parks Woodworking Machine Co., The..... 128 and each advertisement carries Remington Arms Co.. . 118 Porter-Cable Machine Co., The........... 129 the insignia indicating ap- eee ee 6 ey | nde = oC PPO TTT TTT Terre B proval . Manufacturi oO. : H sti s Saw & Steel 100 However, other products Business Opportunities South Bend Lathe Works................... 125 advertised in the magazine a ee 156 Ss Rule & Level Plant, The.......... 95 * American Products Co................... 138 Starrett Co., TheL.S............-..+-- 91 not subject to test carry the Central States Manufacturing Co......... 134 Templeton-Kenly & Co....-.-.----------- 124 — erenennes to readers as Hesslein, William......0.0..000.00000 000000, 154 ‘aco Tool Works seer ee ee ceceeee ucts tested. 5 Seco 44S w (ota s oalncmecal 12 bey & Co., J. b. ARC PRT = P + eed ~— rere errr of @merenwemer Cou, Ime, ..... 2.2. ccccccee sara, i. 5, 66:8 0s6 1) 3.8. Si ae ae 3 Witte Engine i acl Reid 128 THE PUBLISHERS Newcomer Associates................-... 154 Public Service Mills, Inc.................. 144 General. Mogedale, MME: ..... 6... cece nce ces 153 eC Second C = OS ON See re ers 146 General Electric Company........... ‘over Nati Electrical OS 146 oer | Co. “hate: Rasenen se rertey nanansos iss ; he oe aeons eae Whirlwind SEER eae Typewriters, Writing Materials, Etc. niinntaee€in..........., Te ND SREP 151 Wire Grip Sanitary Brush Corp........... 146 Inkograph Co., Inc... ............-.-.-.-. 144 New York Electrical School, The.......... 136 International ! typewriter 6 sai calc 128 = mead bs ork Inst. y beep le meses = Miscell. : orth American Schoo rawing, Inc... . iscellaneous Smith & Corona Type Co, L.C.. ........ a artes 2 — of Taxidermy........ = a on ec : : IN cn | a o6de kes danas end ony ureau 0; fg ng MN, oc a daie eae Smoking Materials Pelman Institute.................--.6-5- $05 Gammmtell Ca, Wm... 0... cee cece eceees 132-156 Camel Cigarettes. Back Cover Perfect Voice Institute................... 144 Crusader Apparatus _ Seer er es 116 Larus & Brother Company. . PPM LES Radio Institute of America............... 135 Kelsey Co., The..... A ee 120 | weedy Television ee eaten aaeh i7 a —- en Corp.. wate os hoo! Engineering of ilwaukee....... 146 ns cosa atc ensesccnssee Musical Instruments Standard Business Training Institute... 134 Open Road for Boys Pub. Co.. 156 Instrument Co... ........ - _ lc (t:t:tOCC, OS 138 Paris American Pharmacal Co.... 152 Conn, ~~ rrr eee 104 Universal Plumbing School............... 145 Plymouth Rock Squab Co........ 114 Se 124 ee 142 Redding Masonic Supply Co..... Pe 130 Pan- can Band Inst. & Case Co...... 142 RO SS eer ere 123 Scientific Electric Works................. 112 aay & & Son, a 156 Utilities Engineering Inst................ 151 Oe ore 144

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DecEMBER, 1929 POPULAR SCIENCE MONTHLY 9 Airplane Flies 368 Miles an Hour! NELSON’S roosetear BNC Y CLOPADIA New Today—New a Year from Today. Still New Ten Years | from Today It is new today. It will still be new six months from today. It will STILL be NEW ten years from today! For each volume of NEL- SON’S is bound with a patent loose-leaf device. Every six months replacement pages are sent to subscribers containing revisions and additions covering all the latest developments the world over. It is simple and easy to “‘unlock’’ the binding, take out the old pages, and Radio to Send Movies Into Our Homes! Wireless Telephones Soon Universal! What Will Science Give Us Next? Nelson’s twenty-two years ago recognized that an Encyclopedia bound, stitched, and glued in the ordinary way cannot keep pace with the world’s progress; it is inevitably out of date soon ‘ after it is published—perhaps even before it is | ya ready for delivery—because of the con- stant development of NEW KNOWLEDGE. ° substitute the new ones. You have a new Encyclopzedia every six months. Experts all over the world are constantly supplying the information that keeps your Encyclopedia always new and reliable. Among the hundreds of new articles are Radio and Television, Busi- ness Combinations and Mergers, Battleships and Cruisers, Farm Relief, Kellogg Peace Pact, Graf Zeppelin World Flight, etc. etc. This Great AMERICAN Encyclopedia Can Never Grow Old Edited by Americans, for Americans, it covers the whole world of information. It is an authority in the Library of Congress, U. S. Senate, U.S. Supreme Court, and in Libraries, Universities, Schools, and Homes in every State in the Union. Thousands of leading professional men use and endorse it. For the average man or woman it offers the scope of a college course. To students it.is indispen- sable—the unfailing question-answerer. Why buy any Encyclopedia but Nelson’s? It is the only Loose-Leaf Ency- clopedia and Cannot Grow Old. Question Free able information. thousands of pictures. Answer Service FREE- Especially made for Nelson’s—richly designed, dust-proot, with leaded-glass single door. It is a convenience for holding your set and a h d be yours at no additional cost. Size: Height 36’; width 20”; depth 12)”. Send for Illustrated Booklet Free to adults—a beautifully illustrated loose-leaf booklet of sample pages and full information about our free bookcase offer and our Budget Easy-Payment Plan. Equivalent to 1,000 Volumes NELSON’S is a great library in itself covéring thoroughly the latest informatiorpin every branch of human knowledge: - It is illustrated with “For some time I have been using your Nelson’s Perpetual Loose-Leaf Encyclo- pedia in the daily practice of law. I find it of inestimable value. I use it con- stantly in obtaining information relative to questions that arise in our practice, many of which are of a mechanical nature. Though we have other reference works of cyclopedic character, we rarely use them, for the reason that we always feel confident that in turning to Nelson’s Loose-Leaf, we have the latest, up-to- date knowledge placed before us.” —George I. Haight, Attorney, Chicago. and Thirty-three Educational Reading Courses Every purchaser of Nelson’s is entitled tofree A Reader’s Guide to Nelson’s Loose-Leaf membership in Nelson’s Research Bureau. If at any time you are in doubt on any subject, old or new, write to this Bureau with the Zoology—is furnished without cost to all positive assurance that you will promptly re- ceive the latest obtainable and most depend- Encyclopedia, including thirty-three courses on as many subjects—from Aeronautics to subscribers. These courses are declared educational authorities to be equal to a col- lege course in each of these departments. This Handsome Bookcase andsome piece of furniture as well. It will Mail This Coupon THOMAS NELSON & SONS, 381 Fourth Avenue, New York. Originators of the Loose-Leaf Reference System, Publishers for Over 130 Years. Please mail me FREE your portfolio of sample pages, full information about the FREE bookcase and how, by the budget easy-payment pen I can own Ne 's Perpetual Loose-Leaf Encyclopszedia, with Free Membership in Nelson’s Research Library Service Bureau for Special Information, and Nelson’s Reader’s Guide Free. ab an em oh en an en as on a am ead

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i r Try this MEASURE YOUR KNOWLEDGE with the POPULAR SCIENCE QUESTIONNAIRE \Y 1. Why does radium continue to give out heat for thousands of years? —... 2. Are the stars solid like the earth? 3. How was the earth formed? -..... 4. Why is glass transparent? —....... 5. How do we know that the earth is slowly at snpemndan 6. What is an electric current? -........ 7. How was petroleum formed? -.... 8 Do electrons really move through wire when an electric current is flowing through it?-..... 9. What physical changes in your body are produced by fear?............ 10. How do muscles exert power? -..... 11. What are X-rays? 12. Can wesee atoms witha micro- scope? 13. Why does heat expand things and coid contract them?.-........... aie 14. Why does the moon appear to change its shape from time to time? 15. What is the brain made of? 16. Why is it possible that the in- side of the earth is growing hotter instead of colder? -............ = 17. Why is frost more likely on a clear night than on a cloudy one? 18. Does thinking use up the ker’s energy? 19. Which travels faster, electri- city or light? 20. What simple test will distin- guish wool from cotton?.—............. 21. What makes the noise of thun- 0 OEE LLL TE EE 22. Why would men ultimately suffocate if all the green plants were killed?. 23. Does the boiling of water re- move the impurities in it? -.......... 24. How do the living cells of the ody getthe energy with which to do their work 2 ———-............... 25. wtow! is the speed of light mea- sur TOTAL PERCENTAGE — iy ia Into this one brilliant book rd 284 pages as densed the M outstanding i facts about the world we POPULAR SCIENCE MONTHLY ardstic 2 14 DECEMBER, 1929 Brain PS tener utd is talking about the famous “Popular Science Questionnaire.”” Doctors, Lawyers, Professors,College Grad- uates and thousands of others have tested themselves with this Questionnaire. In the panel is the list of questions of which the Questionnaire is composed. How many of them can you answer? Like an Old-fashioned Examination May we ask you to make this test carefully, reading thequestions slowly and giving thought to each one? When you cannot answerone satisfactorily to yourself, put a zero (0) beside it. On the other hand, give yourself credit of four (4) for each satisfac- tory answer. Then when you are through, see how near you have come to making a mark of 100. This is like an ‘old-fashioned exa- mination, but you will find it fas- cinating. The questions all have to do with the wonders of the world we live in. All can be given quick and straight forward answers by any person of education. All of the questions in the fa- mous ‘‘Popular Science Question- naire’? and many hundreds of others, have now been answered, for the first time, in one book— Tue Pocket GulpE To SCIENCE. All that you probably ever will want to know about science is told in this one 284-page book that will fit in your pocket or grace a library table. Curiosity-satisfying facts about the world we live in aremade instantly available to you in simple question-and-answer form in Tue Pocket GuIpE To ScrENcE. You are assured of the ac- curacy of the answers in THE Pocket GuIbE To Science be- cause it has been edited by con- Dr. E. E. Free, who has remarkable genius for condensing the known facts about scientific questions in- to easily remembered paragraphs. SPECIAL OFFER Tue Pocket GuIbE TO SCIENCE is not for sale. It is offered to you without one penny extra cost with a 14 months’ subscription to Pop- ULAR SCIENCE MONTHLY. Poputar ScireNcE Montuty “car- ries on” from where THE Pocket GulDE TO SciENcE leaves off. THE Pocxer Gulpe gives you all that the scientists have discovered up to right now— Poputar SCIENCE Monthy will give you all the im- portant, interesting and new dis- coveries of science for the next 14 months. It takes over 300 articles and pictures every month to tell the readers of Popular SCIENCE Montuty all that has happened in the scientific, radio, mechanical and automotive fields. Your Name in Gold Tue Pocxet Guive To Science is bound in beautiful flexible fabrikoid. We will stamp your name in 22-carat gold on the cover of THe Pocxer Guipe at no extra cost to you if you use the coupon below immediately. We extend to you the Special Offer of a 14 months’ subscription to PopuLar Science Monrtuty (regular price by the month would be $3.50) with the Tue Poc- KET Guiwe To Scrence—all for $2.95, plus the postage. If you are already a subscri- ber to Poputar Science we will extend your subscription 14 months if you accept this offer. }\ live in. \! : 12-29 SEND NO MONEY SCIENCE MONTHLY i \ P R { da : Send no money, just the cou- pee ae Avenue, New York Gutpr TO Scrmneill pay the pon. If within 10 days after you Laccept your offer manne Science Monn, the Pocket pore receive the book and magazine months’ subscription, °0 postage when he erm. If ome within i = oat that you are met sat- postman ye qenoe cof Porutateory to me L Wil Hf rayment enema e every particular, you ane azine are not fully tly refun’ may return them, and your en- oe ‘and you are © — tire payment will be refunded stamp my name in 8 ond promptly and without ques- Ts _— tion. Could any offer be fairer? Name————— a, eens nan caees eee POPULARSCIENCE MONTHLY | “4#** esa a5 uous ordet | ar Seem t 250FOURTH AVENUE = NEWYORK | jey———a7~ss; prefer send $2.95 ee

Page 13

DeceMBER, 1929 POPULAR SCIENCE MONTHLY ll Abe. ah JRBG eee ii 7 4 ; f" y ii =] ia 5 ri Sey ie af “= | = Wi Nitto ©& hes Sth sr = F, S ! eee iy) i me $228 | A 4 : imuiiuic a Ee 4 a - SSS ~—— i; mae’ ke: Bie: Sea = ee ; SS ainid : iPr 4 | i) f # cp | i ‘| Ea | SSS Ee, een 1 Wa pe Ses, 2 wget Bes | ih | - TH! A Tl aa in ae S 3 WT rt Te i = {== SSN f | uh Cn |S ot 2B SS : | Mural by Arthur Covey. Wood block engraving by Howard McCormick GREAT manufactories, towering skyscrapers, moving trains and motors, mighty ships—achieve- ments of man that typify the work of the grind- ing wheel. Yesterday, the mechanic with steel against steel slowly and laboriously milled his stock. Today, grinding wheels and grinding machines fashion even the hardest steel alloys to mechanical perfection on a mass production basis. NORTON COMPANY WORCESTER, MASS.

Page 14

SS ae Se oo eee eee i } { if f ot) lf 12 DVICE is cheap enough and there are always plenty of people ready to offer it, as any buyer knows. The remarkable part is that so many of these people can say very definitely and conclusively just which make of product is “the best.” As a rule, the more limited thei: knowledge, the more positive they can be in their assertions. We on the Popular Science Institute staff get considerable amusement in occa- sionally overhearing some of the counsel that is given to prospective buyers. A commuters’ train was the scene of a typical discussion the other morning, refrigerators being the subject. One man was telling his neighbor that a certain electric refrigerator “had it all over” all the other electric refrigerators on the market—was cheaper to operate, more efficient and superior in every way. As far as we were able to gather, this gen- tleman’s knowledge of the refrigerator in question was based more or less ex- clusively on his own experience, that of his brother-in-law, and some friends who were owners of refrigerators of the auto- matic type. As it happened, the refrig- erator he was praising was a very fine make but it was not better than several other excellent refrigerators now on the market. What the Institute Found OMETIMES, people are skeptical when we tell them that there is no one outstanding refrigerator on the mar- ket today that can be considered ‘‘the best.”” But this is a definite fact proved by the test information on file at The Institute’s laboratory at New York Uni- versity—and this information provides a somewhat more accurate basis for an opinion than the experience of a few users of refrigerators. Every test that Popular Science Insti- tute makes on a refrigerator of the au- tomatic type requires a minimum of twelve weeks’ time, test runs being made at six different temperatures and all features of construction and operation receiving careful check. An idea of the extent of these tests and the complete naturt of the data obtained may be gathered from the fact that one of the few commercial laboratories in the country that is equip- ped to make similar tests charges $750 for putting a refrigerator through just one part of the series of tests to which POPULAR SCIENCE MONTHLY The *‘Cream” of the Market IMILARLY, in the case of the other types of products that The Institute investigates—radio, tool, and oil heating equipment—it has been found that invari- ably a small group of very fine products rather than one single product that could be considered most superior, is at the top. Between products of such equivalent merit, any selection of the best would come down to a matter of opinion, and Popular Science Institute feels that it is the buyer’s opinion that counts when such a scant margin of choice is involved. When making a selection from among a limited number of products whose merit and value have been established by care- ful test, satisfaction is bound to result in any case, and the highest degree of satisfaction will result when the basis of choice has been the buyer’s personal preferences and requirements. Therefore, when a prospective buyer uses Popular Science Institute’s approved list as a guide in buying, he is absolutely protected and certain to get well made equipment that represents good value and will give satisfactory service. The Institute’s knowledge of the merits of equipment in the four classes of products it investigates is based on the complete facts in every case, and its decisions as to which makes deserve approval are absolutely impartial. Where the Tests Are Made HE Sage Research Laboratory at New York University, with its $350,000 worth of testing equipment, is the Popular Science Institute’s testing headquarters. Every product is put through most severe laboratory and practical test, and every essential fact that neéd be known about the product is determined. The tests are made by engineering experts with excep- tional experience and ability. Products are approved solely on the basis of test and investigation findings, all decisions being in the hands of Dean Collins P. Bliss of New York University, who is Director of Popular Science Insti- tute. Professor Bliss is Associate Dean of the College of Engineering at New York University and is on the staff of theUnited States Bureau of Standards in Washing- ton as consulting mechanical engineer. DECEMBER, 1929 Looking for the Best? A Letter to the Institute Will Bring Sound Advice on Buying Equipment of the Highest Value By F. G. PRYOR Secretary, Popular Science Institute Price Is a Factor OPULAR SCIENCE INSTITUTE does not confine its approvals to prod- ucts in only one price class. What it insists on is that equipment represent good value and be up to the standards for its own price class. Of course, in all types of equipment, there is a price limit below which no worth while product can be manufactured, and Popular Science In- stitute will not grant its approval to a low priced product unless the manufac- turer has been able to turn out a device for that price which is really well made and capable of giving lasting satisfaction to the purchaser. Use the Institute Service The Popular Science Institute is first and last a service for the readers of Por- ULAR SCIENCE MONTHLY. Its aim is to safeguard them in their purchases of equipment of technical or semi-technical nature. In order that The Institute may function with greatest efficiency and widest usefulness, readers of this maga- zine are urged to make full use of its service. Sound advice and lists of reliable makes of radio, tool, oil heating and refrigerating equipment will be supplied on request. Special questions pertaining to the purchase of such equipment will be answered gladly. Address Popular Science Institute, 381 Fourth Ave., New York. INSTITUTE BULLETINS List of Approved Tools Insulation in Building Construction* List of Approved Radio Prod- ucts List of Approved Oil Heating Devices Advice on Installing Oil Heat List of Approved Refriger- ators Refrigeration for the Home* *Price 25 cents each

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DeEcEMBER, 1929 POPULAR SCIENCE MONTHLY For toys at Christmas time, for industry all the time ...this grainless wood board The discovery of a method to make wood grainless is revolutionizing many indus- trial processes, is giving manufacturers a new material with which to improve products and reduce costs. Perhaps you, too, can profitably use this grainless wood. A sample and the Presdwood booklet are yours for the asking. Both are FREE. | Now tiny tots can play with | wooden toys that will not splinter. Motor truck bodies are made strong and smooth with a material that neither cracks nor splits. Glistening concrete walls of towering sky- scrapers require practically no hand smoothing because of a perfect, smooth board that lines the forms. All these develop- ments, and scores of others in manufacturing and building, are possible today because of the grain- less wood board, Masonite Presdwood. Manufacturers find that Presdwood has many properties which adapt it to production methods. Builders find its smooth surface, its uniform 14th inch thickness, and its broad four foot by twelve foot pieces ideal for paneling, display booths, closet lining, breakfast nooks, and for lining ventilator and elevator shafts. | Easily worked—in factory or home While the grainless nature of Presdwood is per- haps its most remarkable feature, it is far from the only property which makes Presdwood popular. This grainless wood is hard, smooth, strong, and dense. It never harms fine tools; it can be punched, die cut, milled, or sanded; it is also ideal for the home mechanic who has little to work with but a hammer and saw. And when an article is completed it can be left just as it is because of Presdwood’s natural beauty and resist- ance to moisture, or can be given any com- mercial finish. FOR CHILDREN’S CHRISTMAS TOYS FOR WEATHER RESISTING SIGNS LI Fe > : Ae asonite ™. |_¥ A LAE PRESDWOOD I OA cnsomrne Sinticrunar tesuarion [Seal || F9 ; nd ZEEE ZS This grainless wood is used in radio cabinets, tension boards for loud speakers, beds of portable billiard tables, book cases, kitchen cabinets, show cases, and china closets. It makes strong shipping con- tainers, weather resisting road signs, light partitions, durable work bench tops, and attractive novelties such as bedroom screens, fire screens, and trays. FOR LINING CONCRETE FORMS Lines concrete forms Building contractors reduce labor costs on concrete work as much as 40 per cent when Presd- wood lines the forms, for the face of Presdwood leaves the concrete perfectly smooth so that the process of polishing with carborundum bricks can be entirely eliminated. Every manufacturer, builder, and home me- chanic should read the fascinating story of wood made grainless. It is the record of a scientific experiment with live steam at 1,000 pounds pres- sure—an experiment which revealed a way to make grainless wood commercially. The Presdwood booklet tells this story, lists 80 uses for this grainless wood, and tells how various finishes should be applied. The booklet and a sample of Presdwood are yours for the asking. A postcard brings them. MASONITE CORPORATION Dept.732, 111 West Washington Street Chicago, Illinois 13 FOR STURDY SHIPPING CONTAINERS - © 1929 M. C. | |

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a o Do You Agree? “WHY do you and others persist in using the awkward and confusing word ‘non- inflammable’? Bearded etymologists may pro- duce all sorts of justifications for this word, but sensible and practical people usually avoid it because its meaning is so cloudy. To the average person, ‘flammable’ means something that can be burned. ‘Inflammable,’ then, naturally should mean something that cannot be burned. ‘Noninflammable’, therefore, sug- gests a double negative having the same mean- ing as ‘flammable ’—exactly opposite to the meaning intended by its users. The word is not wrong structurally, but it is stupid because of its unnecessary repetition, and it © violates common sense. “If your writers like ‘large, round words’, may I suggest ‘incombustible’ as conveying the meaning that ‘noninflammable’ so im- tently strives to impart.”—A. R. M., troit, Mich. Poputar ScreENcE MONTHLY, not persistent philologicelly, holds no brief for awkward “non- inflammable.” But are there no arguments on the other side? Something to Worry About by ONE paragraph of your recent article on digger wasps the writer says large numbers of the wasps may be liberated to fight injurious caterpillars. Later, he states that when the wasps first hatch out they live on fruit juices. “What I want to know is how they get the juices without harming the fruit, and how farmers will be better off with swarms of wasps eating their fruit than they are now with caterpillars eat- ing the leaves. My advice is to let Nature alone.” — R. F., Columbus, Ohio. A Pat on the Back “T AM delighted to see that you are making ‘Back of the Month’s News’ a regular department of the magazine. It is one of the most interesting and enlightening features you have included in PopuLtar ScteNcE MONTHLY im many a day. Karl Vooght possesses the happy knack of chatting about scientific sub- jects in such a manner as to both instruct and entertain the lay reader and that, unless I am mistaken, is the real attraction of your publication.” —H. A. McK., Omaha, Neb. What! No Science in Cockleburrs? “TP ARNSTORMING with Lindbergh,” by Randy Enslow, was a nicely written and entertaining article and one which is sure to give some pleasurable moments, especially to your younger readers. But may an oldster like myself, who has been an interested reader of Poputar ScrENcE Montaty for nearly twenty be permitted to ask why you considered it @ suitable contribution to your particular magazine and ‘played it up’ in the bargain? Of the popularity of this sort of yarn there can be little doubt, but by what stretch of editorial imagination could it be called scientific? “Tt seems to me that little, if anything, is added to the sum total of human knowledge by telling the world that Lindbergh at one time POPULAR SCIENCE MONTHLY regarded the placing of cockleburrs in people’s beds in the light of good, clean fun, and that he was an exemplary boy who never drank, swore, or smoked. *‘An article like this is bound to have two undesirable effects. First of all, it will inspire hundreds of youngsters with the ambition to be aerial stunt-artists; and, secondly, it will hasten the day when conservative citizens like myself, who began by admiring Colonel Lindbergh, will involuntarily be turned against this young man as a result of the superabundance of publicity the editorial fraternity is thrusting upon him.”—M. P. W., Ithaca, N. Y. Not Sighted Yet was turning over some of my back numbers of PopULARSCIENCE MonTHLy when I came upon the article about the sixty-hour transatlantic speed boat in the April, 1928, issue. This article said that Adrien Remy, French inventor, was put- ting the finishing touches on the new craft, which consisted of two large pontoons between which the cabin, motor, etc., were suspended, and that he planned soon to start for New York. “‘T was just wondering why it hasn’t arrived yet.”—C. H. B., Brooklyn, N. Y. And More Coming ““T WANT to congratulate PopuLar ScIENCE MONTHLY on some of its recent articles which have been extremely interesting. As a reader who, like J. P. F., of Chicago, does not go in much for aviation news, I have been especially pleased by the features on other subjects. The article on plant pills was particularly good, and I hope P. S. M. intends to keep in touch with further developments of that sort and let its readers know about them. “E. E. Free’s articles, one in the Qctober and one in the November issue, on ‘Everyday Wonders in Colloid Chemistry’ and ‘ Rays—the Clue to Evolution’ respectively, were fine. I hope that Dr. Free will continue to help readers like me to keep up with some of the broader phases of science. And even if I don’t read much aviation stuff, I must say that the Zeppelin and Lindbergh articles in the October number were humdingers.”—A. W. K., Arlington, Mass. After You, Professor 7 SEE by PopuLar ScIENCE that Professor Goddard is going to catch sunbeams and make them run everything on a farm from tractors to washing machines. It’s a great idea —there’s real farm relief for you! Now what the pro- fessor and Einstein ought to figure out together is how to put the cows on wheels and the chickens on trolley wires. Pipe lines for milk and endless belts to bring eggs from the henhouses might help, too. DeEcEMBER, 1929 “Perhaps I’m a back number. But I guess T’ll just keep running my wasteful, inefficient farm in about the same old-fashioned way I always have. I don’t think I’ll scrap my gaso- line lighting plant and my backfiring tractors just yet. It’s all very well for a college pro- fessor to tell us how to make sunbeams work for us. But my suggestion to him is to get him- self a farm and try it out himself first.”— G. H. B., Centerville, O. One of the Sciences “@. F., of Madison, N. J., writes as his argu- ment against aviation articles the fact that articles on physics, geometry, and other sciences of that type should be published more than those about aviation. That is all very well, as they make fine reading, but I don’t think that aviation should be made the ‘goat’ for them. Aviation is as much a science as any of the others and should be dealt with accord- ingly. “As S. F. said, there are strictly air maga- zines for people of my type who like aviation and are air-minded enough to see its future. As a counter stroke I say that more articles about aviation in magazines of all types will help speed its progress. “Tt will not be many years until the nation with the largest commercial air transport system will be the leader, just as it was on the seas in olden times. The others will just follow and take what’s left. Although I don’t want to prepare for war, the nation filled with more privately owned planes will also have the great- est war strength, because it takes but a short while to turn a good civilian plane into a fighter. “Tn closing—let’s have more aviation articles and boost that field of science sky high.’”’— R. D. P., Fairbury, Ill. Stuck! “TL... E. FREE’S article on colloid chemistry told how colloids help us shave, cause cataracts on the eyes, and make postage stamps stick. The part about rouge sticking to a flapper’s lips with a pres- ' sure of 200,000 pounds to the square inch raised an argument in our family. At a movie the other BY of night the heroine kissed J the hero and left rouge marks on his cheek. What we want to know is, if it \ takes a pull of 200,000 pounds to the square inch to pull off rouge, why this didn’t hurt. My daughter thinks it did, but that they were enjoying themselves too much to notice.’”—E. D. R., Reno, Nev. The Old “Grey Wolf” . WE ARE very much interested in the auto- mobile story ‘Scorching in My Horseless Carriage,’ and in the pictorial section, ‘Tracing Your Car’s Family Tree.’ There are so very few men who remember the old days of the automobile, new as the industry is, that per- haps one writing on the subject might be pardoned for overlooking many interesting facts. “The story talked about high speeds of TANGLE FOOT. RR

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DecEMBER, 1929 POPULAR SCIENCE MONTHLY 15 COOLS while you shave and the coolness lingers! Listerine Shav- ing Cream. Do you remember— When the good old family doctor came into the house how your heart began to thump? You didn’t know but what you had cholera morbus or something equally dread- ful. You saw yourself dying in no time. Then his firm, gentle hands poked you here and there. His bright, kind eyes looked down your gullet. And, oh, what a load left gd mind when you learned that your trou- le was only a badly inflamed throat and that Listerine would take care of it! The basic things of life seldom change: Listerine, today, is the same tireless enemy of sore throat and colds that it was half a century ago. It is regularly prescribed e the bright, busy young physicians of this day, just as it was by those old-timers— bless their souls —who mixed friendship and wisdom with their medicines. Used full strength, Listerine kills, in 15 seconds, even the virulent Staphylococcus Aureus (pus) and Bacillus Typhosus (ty- ee germs in counts ranging to 200,000,- . We could not make this statement unless we were prepared to prove it to the entire satisfaction of the medical profession and the U. S. Government. Three well-known bac- teriological laboratories have demonstrated this amazing germ-killing power of Listerine. Yet it is so safe it may be used full strength in any body cavity. Make a habit of gargling systematically with full-strength Listerine during oan weather. It aids in preventing the outbrea of colds and sore throat. And often remedies them when they have developed. Lambert Pharmacal Company, St. Louis, Mo., U. S. A. It checks SORE THROAT quickly Gargle with full-strength Listerine every day. It inhibits the development ofsore throat, and checks it, should it develop. How to prevent a cold Rinsing the hands with Listerine before every meal destroys the germs that lodge there. KILLS 200,000,000 GERMS IN 15 SECONDS

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16 thirty miles an hour at a time when the Packard four-cylinder car was being built. It ight interest you to know that this four- cylinder car followed the Packard Grey Wolf, which was the first car to make a speed of a mile a minute. Incidentally, this car had a spiral beveled gear in the rear axle, which really was the thing that made possible abandonment of chain drives about which your story deals.”—H. F. O., Packard Motor Car Company, Detroit, Mich. PPpP?P?y? “Ex NOT going to answer S.K.’s question ‘Where did the lost flying hours go?’ in the way that he expects. Instead I’m going to ask him a question. How many different combinations of numbers did he try? Here are two he missed. oan hg "apo e plane to ty miles Za Z an hour and the velocity ag 4 of the wind fifty. With the wind, according to S.K.’s reckoning, the oma will go 100 miles an ur and take three hours to cover a 300-mile jour- ney. Now when the plane starts back, if one accepts his reckoning, its speed is no miles an hour. In other words it stands still. “Suppose the figures to be fifty miles an hour for the plane and 100 for the wind. How long will it take for the machine trying to ‘buck’ the wind to reach a place of the same latitude 300 miles away? Assume the circum- ference of the earth at our plane’s latitude to be 24,000 miles, then the correct answer is 474 hours-—and it will arrive tail first! Figure it out.”-—M. P. R., Columbus, O. *‘Simple Arithmetic”’ “HE mysterious loss of two hours in S.K.’s flight from Los Angeles to San Francisco and return is accounted for quite easily. The plane travels at 100 miles an hour. The dis- tance is 300 miles. The air velocity is fifty miles an hour. The plane therefore makes the trip with the wind in two hours and against the wind in six hours. This is simple arithmetic. The total flying time is eight hours as compared with the six hours which would quite obviously be required for the trip if there were no wind. The difference is two hours. More simple arithmetic! “The plane is in the air a total of eight hours, during which time it is carried by the wind a total of 200 miles. The plane’s speed is 100 miles an hour, so that it has to travel the extra two hours to make up for the distance it is carried by the wind. Still more simple arithmetic!” —N. K., Baltimore, Md. From Bald-Headed Row x (THREE cheers for page 55 of your October number! The comely faces of our flying gals certainly came as a welcome relief from the surfeit of portraits of gadgets and their sober-visaged inventors you have been giving us since [ became one of your readers. “Far be it from me to wish that PopuLaR ScreNcE Monruty should turn frivolous in its old age, but, after all, even the scientifically and me- chanically minded are only human and none of us enjoys a case of eyestrain. Please repeat.” —B. A. S., Chicago, Ill. Changed His Mind “] THOUGHT I would discontinue taking the magazine, but each number was more interesting than its predecessor.”—A. K., Ludington, Mich. POPULAR SCIENCE MONTHLY Who'll Help Him Out? as Y SON reads your magazine faithfully, but I am sick of having it around the house. Every month you get all heated up because somebody has in- vented something. What of it? Have the inventions we have now made men any wiser or more intelligent? Do they inspire any greater thoughts? Not a bit of it! When the phono- graph was invented, the first words spoken into it were: ‘Mary had a little lamb.’ When the telephone was invented, the first words spoken through it were: ‘Come here, Watson.’ And to inaugurate the transatlantic telephone, the Mayor of New York said to the Mayor of London: ‘How’s the weather over there?’ “Why get excited because radio travels around the world when it usually carries some- thing like ‘I Faw Down and Go Boom’? Why have catfits over the talkies when they are used to let us hear the splash of the custard pie that hits the comedian’s face? Why rave over the wonders of the electric light when it keeps people running around at night when they ought to be in bed? “Tf any reader of your magazine can point out one single thing this flood of inventions has done to elevate man’s mind or make him hap- pier, I wish he would do it.—M. O. R., New York, N. Y. A Cure for Loneliness “BENG a regular reader of your very interesting magazine, and having built the Sovereign of the Seas, Constitution, and the Santa Maria from your articles by Cap- tain McCann, and having won several prizes with same, I am in- closing your coupon with blueprints marked for the pirate ship, the Spanish galleon, and the Mayflower. “As an old English apprentice serving my time in sailing ships out of Greenock, Scot- land, I take great pleasure in making these models, and I have pleasant memories when I read Captain McCann’s explanation of dif- ferent parts of the vessels such as lubber holes, clews, sheets, and buntlines. It will no doubt be a great pleasure for Captain McCann to know that, as I am now stone deaf, he has the means of giving me unlimited pleasure and happiness in building these models and so keep my mind off my affliction. It surely takes the -loneliness out of my evenings, and I am wondering if I may make the suggestion that he will some time give us a model to make and put in a bottle, as we used to do on the old skysail yarders.”—G. C., Rapid City, Mani- toba, Can. In a Nutshell “FT SUBSCRIBED ‘to Poputar ScIENCE MONTHLY as an experiment. Now I feel that it is one of the most interesting magazines published and that I cannot get along happily without it.”—M. L. A., Gloucester, Mass. “PopuLar SCIENCE MONTHLY is the best magazine dealing in mechanics and kindred subjects I have ever had the pleasure of read- ing.”—W. C. W., Hornsby, IIl. “Your magazine is in line with my work and I enjoy reading it. I am building a new motor and will tell you about it when it is finished.” —W. C. M., Donnelsville, O. “Wish Poputar ScrENCE came every week. Cannot be without it.”—G. C. S., Taft, Calif. “T agree with S. F., of Madison, N. J., that PoputarR ScrenceE Montaty should ‘print more chemistry, physics, and geometry, -but I do not wish for any of the aviation news to be abolished.” —J. D. McPh., Birmingham, Ala. DeEcEMBER, 1929 “PopuLAR ScreNce Montaty is fascinating in all its departments. I especially enjoyed Mr. Keyhoe’s article with the wonderful pictures of ‘Lindy’.”—Mrs. A. M. G. T., Philadelphia, Pennsylvania. “T think your magazine is great. I have been reading it for several years and cannot find better scientific reading matter. Keep up the Home Workshop and radio sections.” —L. L., Richmond Hill, N. Y. “T would like to take this opportunity of complimenting you upon the wonderful make- up of your journal and to say that it has afforded me many hours of interesting and educational reading. I believe it has no com- petitor in its particular field. You are to be congratulated.”—J. C. H., Los Angeles, Calif. A Helpful Habit “T HAVE a habit. It’s a peculiar one, but very helpful at times. Often it is necessary, or at least desirable, to hold a flashlight so that it will shine wherever you need it, and still have both hands to work with. This can be easily accomplished by holding the light between the arm and the body just below the armpit, and gives surprising freedom in the use of the arm.”—R. B. H., Vicksburg, Mich. Scrap the Submarines? “‘7OUR articles dealing with submarine disasters have interested me greatly. I think that some of the safety devices you described were really ingenious, but if the sub- marine is sunk in really deep water all attempts at rescue are useless. The tragic sinking of our own H-47 brings this fact to light. She was sunk in sixty fathoms and after a brief attempt all salvage operations were abandoned. The loss was fourteen young men. “These terrible disasters have aroused a storm of protest over here and the general idea is to scrap subs. What do your readers think of it?” —G. N. G., London, England. The Retort Courteous “TE MRS. D. B. J. on your November ‘readers’ page trying to be funny? Or is she just old-fashioned? For many men who are troubled with bad dreams the words ‘sin’ and ‘conscience’ have long ceased to have any meaning. If Mrs. D. B. J. really wants to know, I hope she will take a bachelor’s word for it: the cause of this misfortune is probably that too many men have wives like her whose nagging haunts even their husbands’ sleep.” — R. H. D., Olean, N. Y. From the Sick Room “PrORanyone whoiscon- fined in bed as an in- valid, PoputaR SCIENCE MonrTHLy is a life-saver. It is one of the few maga- zines that gives a person something worth while to think about when he has nothing to do but lie still and think. I enjoy every page of it.”.—F. S., Monrovia, California. Worth Preserving “AATAY I compliment you upon your roto- gravure section. When you added the feature I thought it would be just another jum- ble of freak pictures. Instead you have made something fine of it. Your recent picture pres- entation of Edison’s career, the development of the airplane, and Lindbergh’s life are features which I am sure will be preserved in many American homes for years to come.”— R. U., Pittsburgh, Pa.

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DecemBER, 1929 POPULAR SCIENCE MONTHLY >> ON DUTY WITH THE NEW YORK STATE POLICE << FROM THE CANADIAN BORDER TO LONG ISLAND SOUND, PATROL CARS CARRY THIS UNFAILING WINTER PROTECTION » » EVEREADY PRESTONE

READ what Major John A. Warner, Superintendent, has to say about the use of Eveready Prestone, the perfect anti-freeze, in the cars used by the New York State Troopers in the perform- ance of their duties: “We are glad to inform you that our experi- ence this winter in using Eveready Prestone in the cars operated by the New York State Police has again been a happy one. “This present winter is the second during which the anti-freeze has been used, and thus far we have had no single instance where com- plaint has been found with it. It has been em- ployed with different makes of cars, and under the most trying of weather conditions. In the performance of their duties, our men range from the Canadian border through the Adirondacks down to the southern parts of the State. Fre- quently they are on the open roads for hours at a time, during which their cars must function under all sorts of stress and strain.

“It is gratifying to us that during the past two years Eveready Prestone has contributed so materially to the success with which the State Police have been able to carry on their work,” Whenever men, engaged in haz- ardous cold-weather duties, en- trust their lives and reputations to motors, there you will find Ever- eady Prestone. At Army flying fields. At Navy air stations. With Commander Byrd in the Antarctic. And one supply of Eveready Pres- tone will provide your motor with the same permanent protection against freezing. It possesses al] the properties pointed out by the National Bureau of Standards as essential for an anti-freeze. 17

Eveready Prestone does not contain any alcohol or glycerine POINTS OF SUPERIORITY Gives complete protection. Does not boil off. Positively will not damage cool- ing system. Will not heat up a motor. Circulates freely at the lowest operating temperatures. Will not affect paint, varnish or lacquer finishes. Non-inflammable. Odorless. Economical—one filling lasts all winter. oono uh won TEST 80, S ARS Thoroughly tested and 100% ( aie a) approved by the American ce aa way Automobile Association EVEREADY PRESTONE CTRAOE-MARE 8E0.) FOR PREPARATION OF THE PERFECT ANTI-FREEZE Once the cooling system of a car has been flushed out and tight- ened, a single supply added to the radiator will provide trouble-free surety against all freezing haz- ards through all kinds of weather. It is time now to have Eveready Prestone in your car. You can buy it at the nearest garage, filling sta- tion, automobile supply shop or hardware store. NATIONAL CARBON CO., INC. General Offices: New York, N. Y. Branches: Chicago Kansas City New York San Francisco Unit of (Tae and Carbon Union Carbide (odouisuus Corporation

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18 POPULAR SCIENCE MONTHLY NOISE upsets your entire organization .- + hampers the clear thinking of your executives ... encourages the errors of your subordinates ISTEN to the steady succession of noises in the average office. Just hear the clatter of typewriters, clamor of telephones, slamming of doors, the constant rise and fall of voices. This disturbance places a handicap upon your entire organization. For all these noises echo and re-echo from the ceiling... making a nerve- wracking undercurrent of sound that cuts into concentration and destroys a share of each man’s value. None of the people you pay to think ever gets used to NOISE. And in a year’s time it writes a big entry on the debit side of your ledger. 3 So progressive business men are put- ting an end to unnecessary noise with Acousti-Celotex, the noise-absorbing Acousti — [ELoTEx FOR LESS NOISE—BETTER HEARING fibre tile, applied to their ceilings. The list of companies who are eliminating costly errors and speeding up office efficiency with Acousti-Celotex is filled with familiar names. Acousti-Celotex has clearly proved its value in hundreds of these installa- tions. It can be quickly and easily installed in new or old buildings. It comes in rigid, finished units easy to keep clean, and can be painted even with lead and oil paints without losing its sound-absorbin g efficiency. Architects are using Acousti-Celotex DecemBeEr, 1929 in hospitals to provide restful quiet— in schools and colleges to insure less noise and better hearing — in churches to eliminate echoes and reverberating sounds— in moving picture theatres to improve the presentation of sound- pictures. Mail the coupon below for our interesting booklet, “Acousti-Celotex versus Noise;” with complete informa- tion about this remarkable material, showing in detail how Acousti-Celotex subdues NOISE inall types of buildings. The Celotex Company, Chicago, IIli- nois. In Canada: Alexander Murray & Co., Ltd., Montreal. Sales Distributors —everywhere. Acousti-Celotex is sold and installed by Approved Acousti- Celotex Contractors. The Celotex Com Chicago, Mines THE CELOTEX COMPANY 919 North Michigan Avenue, Chicago, Illinois Please send me your interesting free Booklet — Pop. Sct. 12-29 *Acousti-Celotex versus Noise.” a Address ..........

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s Fo WSS ng —SS ae AN UNDED 1872758 DECEMBER, 1929 TRAVIS HOKE Editor VOL. T15, NO. 6 . ——— A New World Run by Dynamo For months, now, political and industrial leaders and the newspapers have been talking excitedly about “power” and “super-power.” Seldom, however, has anyone explained exactly how or why the discussion is a matter of public concern. This article tells in simple terms why every family and every factory has a vital interest in future sources of electric power, which already has entered 19,000,000 homes, has given to every factory worker the equivalent of 55 helpers, and serves three fifths of the American people. 66 HE North Pole could be made into a summer resort if sufficient power were available.” So de- clared the Earl of Birkenhead, who is one of England’s great- est statesmen and a leading figure in the electric power industry, on a recent visit to the United States. That would be a fanciful project. The largest electric dynamo in the world, a_turbo- generator of 165,000-kilo- watt capacity recently installed, together with an- other of equal size, at Hell Gate power station in New York City, would be doing well to turn 300 acres of that vast frigid region into a garden spot. But what electric power is doing right at. home, in the United States, is fully as startling and far more practical. The fact is that the world is face to face with a second industrial revolution. One hundred years ago the first industrial revolution, which Watt started with his inven- tion of the steam engine, was well on its way to trans- forming the world. Facto- ries and mass production followed in its wake. A worker who laboriously fashioned a few nails from wire daily by hand now stood at the levers of a ma- chine that made them by the thousand. The second revolution promises to eclipse the first. Electricity has brought it about. Installation of boil- ers and -steam engines in factories is virtually at a standstill. Not everyone By GROVER C. MUELLER knows that the power situation has so changed that more than three fourths of America’s industry is electrified. “Power” means “electricity” today. The Dynamo Era is here. It is sym- bolized by gaunt pinnacles of high tension towers that dot the countryside. Power as fluid as water flows along metal'strands from distant power house to factory. The Niagara’s thunder is reflected in the roar of the 70,000-horsepower turbines that harness the waterfall and send its power flashing over high tension wires. mere snapping of a switch puts its brute force to work. It is strong enough to forge glowing steel ingots into rails and wires. Because it is not bulky, as coal is, it can be shot over thin wires to industrial plants far from cities, even to manufactur- ing plants located in remote and inac- cessible places. It is clean. And it is so economical that it is setting new styles in mass production. Industry is not alone in benefiting by the revolution that brings electric power. Electricity has entered nearly 19,000,000 homes. It serves three fifths of the American people. It heats 17,000,000 flatirons, runs 7,700,000 vacuum cleaners, and operates 5,700,000 washing machines. It fills more than a million ice chests, and cooks in 725,000 stoves. A dollar’s worth of electricity before the war costs only eighty-two cents now, according to Paul S. Clapp, of the National Elec- tric Light Association— though living expenses, in- stead of falling, have risen sixty-five percent. HAT is ahead? The late Charles P. Stein- metz, electrical engineering genius, predicted that elec- tricity, by doing most of the world’s work, would release everyone to almost bound- less leisure. Super-power, the mass production of elec- tricity by a few central sta- tions in the United States, may bring it about. It is the dream of engineers, and the next logical step in the new revolution. 19

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= TEIN FET SA 5 ST aac Boas POPULAR SCIENCE MONTHLY One of the two largest generators of electric power in the world, which was recently installed at the Hell Gate power station in New York City. It is a turbine generator of 165,000 kilowatt capacity. When cheaper and more abundant power comes, a factory worker will per- haps toil but two or three hours a day. Electric machines will enable him to ac- complish in that time what it takes a present-day workman a full day to per- form. In the home, the revolution will be as complete. Cooking with electricity will be the custom, instead of a luxury. Homes will be heated by electricity. Other uses will be found which no one today can possibly imagine. UPER-POWER, as conceived by en- gineers, means hooking up all power plants into one vast web that would span the whole country. Perhaps there would be no more than a hundred power houses in all—giant factories of power that would eclipse any in existence today. Califor- nia and Pennsylvania would exchange power. Because of differences in time across the continent, one section of the United States could help to supply the nighttime demand of another. When night approached in New York, Chicago s power houses would help to light the gleaming lamps of the “Great White Way.” As darkness spread to the Middle West, Colorado and Nevada and other far western states would switch in their dynamos to help shoulder the burden of lighting the states to the east. Almost by the time the West grew dark and com- | ps Pi , lo! | GENERATOR q 4 * * Pe j q ae Diagram of one of the 70,000-horsepower turbines at Niagara Falls. A loco- motive could run through its penstock, at the right. menced to turn on its lights the East would have turned them off and gone to bed. Moreover, when a drought cut down the power of Niagara Falls, New York with its coal-burning stations could make up the difference. When water was plen- tiful the coal stations would shut down and let the hydroelectric power houses carry the load. Thus the super-power web would be a sort of “clearing house” for electric power. Engineers have gone far toward carry- ing out this bold scheme, despite the great technical difficulties of hooking up power DOLLAR’S worth of elec- tricity before the war now costs only eighty-two cents. In America electricity heats 17,000,000 flatirons, runs 7,700,000 vacuum cleaners and 5,700,000 wash- ing machines, and fills more than a million ice chests. lines serving different sections. Already there is a 1,000-mile triangle of super- power wires connecting Chicago, Boston, and Pensacola, Fla. In a ’ recent test Chicago’s power houses successfully ran the city of Boston. There is a - continuous power supply a chain along the Pacific Coast from Canada to Mex- ico. Wisconsin and Michi- gan are tied up in a mid- western hook-up. Today fully one tenth of all the electricity generated in the United States is used in anofher state from that which produces it. Super-power’s value re- ceived a striking demon- stration in the floods that swept New England and the DeEcEMBER, 1929 Mississippi region two years ago. Indi. vidual power plants in the flooded areas were destroyed. But the electric power went on. Faced with this mass production of electricity, industrial leaders realize that electric power is a commodity, just as tangible and desirable as petroleum or coal. So great a banking firm as J. P. Morgan and Company is now interested in obtaining power sites. Various politi- cal fights have occurred over the question whether power plants should be run by individual private companies, as they are today to a large extent, or by the federal, state, or municipal governments. PF groned the economy of operation by experienced firms, some observers urge the nonmonopolistic safety of public control. There are variations of each of the two schemes, of which a novel one operates with unusual success in Ontario, Canada. This province’s power is owned and operated by the government’s Hy- droelectric Commission, which delivers it under contract to municipalities. The power rate 1s high, but the domestic rate is so cheap that farmers use it even for cooking. Monthly bills in Woodstock, a town of only 10,000 population, have averaged $4.96 for families who were lighting and cooking by electricity. In most cases rates are as low as 1.9 cents per kilowatt hour. Engineers and scientists, however, are more concerned with the realization of great power projects than with who owns and runs them. The project of construct- ing Boulder Dam, which will block the Colorado River with the greatest dam in the world, recently was confirmed - by Presidential proclamation (P. S. M., Nov. ’29, p. 52). Congress has left it with the Secretary of the Interior to decide whether to lease or operate the dam and power house. The 525-foot-high dam will supply both power and water for irrigation to neighboring states. A hydroelectric plant on the Tennessee River, at Muscle Shoals, was erected by the Government during the war to cap- ture nitrogen from the air and use it for the production of explosives. Today a small part of its power is in use, while it is proposed to use the rest for the manu- facture of fertilizer—a subject which has often been discussed in Congressional debates. Another project, at present on paper, is a plan to dam the St. Lawrence and erect a hydroelectric plant of perhaps a million horsepower. All of these familiar subjects of political controversy may soon become important factors in the super- power side of the electric revolution. THER great power projects have helped to give three fourths of Amer- ica’s factory workers the equivalent, in electric power, of a gang of fifty-five la- borers working under each. Niagara’s thunder is reflected in the roar of the 70,000-horsepower turbines, the largest of their kind in the world, that harness the waterfall and send its power flashing over high tension wires. Two 165,000-kilowatt steam- driven generators, big- gest electrical machines of all, have just been added to the mighty Hell

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1929 ndi. reas wer | of hat - as or P. ted jiti- ion by are ral, ers lic yne ‘io, ed ly- it ite or a ve In its i ed | DecEMBER, 1929 Gate plant in New York City, whose twenty-four boilers all but scrape a ceiling 100 feet high. A million-horsepower plant rising near by, to be completed in 1930, will pump a torrent of water from the East River twice as great as the Catskill aqueduct carries to New York, to cool its turbines’ steam. A 208,000-kilowatt gen- erator which will create electricity at 18,000 volts is soon to begin operation in Chicago. With the power of more than 270,000 horses, it will be the most titanic electric machine in existence. These will be parts of the electric network that feeds America’s homes and factories eighty- eight billion kilowatt-hours of electricity yearly. HERE are still untold reserves of power to draw upon. America has harnessed only one fourth of the total water power it has available, according to the United States Department of the Interior. How much power may be added by burning coal nobody knows. Should the coal be exhausted, there would still remain the hope of additional power in harnessing sunlight, wave power, or the tides. Of course those are for the future. Today there are just two important ways to get electricity. Wherever coal is available to be burned under a boiler, electricity can be generated by steam power. Wherever water flows in a river it is possible to build a dam, raise the level of the water, and let it flow down through a turbine. If there is already a natural drop in the river, such as that at Niagara Falls, it saves the trouble of building a dam. Today two thirds of the Nation’s electricity is generated by steam and one third by water power. Because coal costs money and water runs downhill for nothing, many persons imagine that water power is always cheap power. But that is not always so. The cost of constructing and maintaining plant and transmission line, the interest on in- vestment, and losses in transmission must all be paid for by the power user. Another reason water power does not * One hundred thousand horsepower is the capacity of this power house at Wilson Dam, one of the units POPULAR SCIENCE MONTHLY always mean cheap power is that it fluctuates from one season to another. The $50,000,000 machinery of Muscle Shoals is engineered to be capable of producing 610,000 horsepower. When the river is low only 100,000 horsepower is available. The public wants current when it wants it and not in a smooth, steady stream day and night as the com- pany would prefer. That is why, forinstance, New York City has an automatic storm detector at one of its main generating plants. Should a thunderstorm darken the sky, millions of persons will turn on electric lights. Everyone will demand cur- rent at once. Therefore the mechanical storm prophet flashes a warning to the power plants of the city, and the results are as excit- ing asa fire alarm. Klaxons scream above the deafening roar of the turbine rooms. Coal cars leap into swifter action to fill the bunkers that supply the mighty boil- ers. Under the generalship of operators at the power plant’s control board, which is ornamented with switches and flashing lights, fans speed up to force air into ORE than three fourths of America’s industry is electrified. When cheaper and more abundant power comes, workers may perform, in two or three hours, work that now requires a full day. rae i. eae sacs Risin OR seesteom of the huge Muscle Shoals development. The capacity of the entire project is 610,000 horsepower. 21 Courtesy, The Digest Penstocks and power houses of a new hydroelectric power project at Sao Paulo, Brazil. Waters from a mountain river fall approx- imately 2,000 feet to drive the blades of turbine generators. the boilers. Soon the steam pressure rises, ready to help the mighty turbines fight the added load of the storm. Even an eclipse of the sun calls a power plant into sudden action. Astronomers had warned New York power plants that the moon’s shadow would darken half the city during the solar eclipse of 1925, and they were ready. At eight o’clock in the morning the sun’s disk commenced to be obscured. Power officials noticed that more electric lights than usual were going on, judging by the load the electric dials indicated, as the moon’s black disk ob- scured the sun. Suddenly the dials shot up. The eclipse was total. Almost simul- taneously word flashed from the power houses that New York was draining them of 424,000 kilowatts instead of the usual 348,000 at that hour. The sudden increase of 76,000 kilowatts was almost without precedent, but the power plants managed to supply it and New Yorkers had light when they wanted it. But they were care- less beneficiaries of the plans made for them! The power records showed that many, particularly in office buildings, for- got to turn the lights out again after the eclipse, and the demand for electric cur- rent was more than normal all day. ITALLY as these power plants are interested in supplying electricity for light, it is only one of the important uses today. The history of the iridustrial revo- lution that brought it into. factories for power commences in the eighties when an innovation appeared—the electric street car. It was the first great applica- ticn of electricity on a large scale. And, coupled with im- (Continued on page 142)

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22 ak Ste Soa ee See “- > Spat oe a POPULAR SCIENCE MONTHLY Research station and radio transmission towers of the Massachusetts Institute of Technology at South Dartmouth, Mass., where experts are studying methods of overcoming the menace of blinding fog. LYING “blind,” in an airplane cockpit so covered by a hood that he could see only the glowing dials of the instrument board, Lieut. James Doolittle, a crack Army pilot, took off at Mitchel Field, New York, the other day, flew seventeen miles, returned to his starting point, and made a perfect landing. Airmen hailed his feat as an important advance in the efforts of science to conquer the greatest menace of flying—fog. Three new instruments made the “blind landing” possible. One was an “artificial horizon” showing the plane’s lateral and longitudinal position in rela- tion to the earth. Another was a super- sensitive altimeter which recerded the height of the machine to within a few feet of the ground; a third was a new radio direction-finding apparatus. As the machine flew, two metal “reeds” on the instrument board were oper- ated by waves sent from a radio beacon at the flying field. ‘They guided the pilot on a straight line. If the plane swung to the right of a direct line to the field, the right reed oscillated violently, and vice versa. When the plane passed above the sending station, the signals momentarily stopped. This indicated to the flyer that he was above his landing place and he nosed the machine down, judging its height above the ground by the altimeter. In dense fogs, Lieut. Doolittle declared, air mail and transport pilots will be able to land by use of the new equipment, which is the result of eleven months of experiment in fog flying under the direc- tion of the Guggenheim Fund for the Promotion of Aeronautics. This is just one of the recent develop- ments in science’s war upon the white enemy. On the Round Hills estate of Col. E. H. R. Green, at South Dartmouth, Mass., a unique “fog laboratory” has been established by the Massachusetts Insti- tute of Technology for creating and studying artificial mist. The same insti- tution also is aiding in fog tests with the dirigible Mayflower on cruises through real fog banks near its home base on the Round Hills estate. Yet this blinding white vapor remains unconquered. It continues to put out the eyes of traffic on land, sea, and air. Not long ago, the London Chamber of Commerce estimated that the cost of a “pea soup” fog to that city in accidents, delays, and curtailed business was $5,000,000 a day. Ten thousand men, working a third of a year at the average wage, would just pay that one day’s Hooded airplane cockpit in which Lieut. James Doolittle, Army pilot, completed his remark- able “‘blind’’ flight of 17 miles. Instrument board of Lieut. Doo- little’s plane, showing “blind”’ flying aids—a special altimeter (A), “artificial horizon’’ (B), and new radio direction finder (C). DECEMBER, 1929 _ First Victories in the War on Fog OG costs the world mil- lions of dollars a year in transportation de- lays and accidents. It is the arch foe of flyers aiid marin- ers. A bucket of water in the form of fog can tie up the port of New York or London, and can send air- plane pilots to their death. This article describes im- portant gains in the first large-scale attempt of sci- ence to conquer the worst of man’s weather enemies. By EDWIN W. TEALE damage bill. A “London particular” once settled over the Estuary of the Thames and lasted for five days. No vessels could move. The estimated loss to shipping alone was a million dollars a day. In May, 1928, a cloud of mist that remained for forty-eight hours tied up traffic in New York harbor. Eight ocean liners collided. To swift-moving airplanes fog is a supreme danger, for it cuts off the airman’s view of the ground and makes landing a gamble with death. N OTHER ways than paralyzing traffic and causing accidents, fog exacts its toll. A few years ago, Dr. F. W. Oliver, noted botanist of the University of London, discovered in experiments that it injured growing plarts in the London botanical gardens by interfering with the production of starch by the leaves, which takes place when the weather is clear and sunny, and by depositing layers of dirt and acids upon the plants that often turns them yellow and causes leaves to drop off. The minute water particles of fog seem to ‘“‘fine-comb”’ the air, collecting the acids, notably sulphuric -. kk cede Bee oe el lUenlCUelClUee oe UeehlCOe ee Jee,

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\. sw = DecEMBER, 1929 acid, which are given off by coal fires. These acids not only injure plants but eat into stone buildings. Experts of the British government now are conducting experiments to prevent the erosion of buildings by the action of fog. One of the unusual ways in which fog causes damage is reported by a Long Island radio broadcasting station. Sev- eral times in midwinter dense fog banks, rolling in from the Atlantic, have envel- oped the antennas. The moisture, freezing to the wires, has weighed them down until they have snapped, interrupt- ing programs. To relieve the strain on the wires in such emergencies, the an- tennas are now equipped with counter- weights, like those in a window sash, which rise as the weight of the wires increases. CCASIONALLY, fog proves a friend of man instead of anenemy. Once, it helped put out a forest fire that was eating its way through valuable forests in the state of Washington. During rainless summers in southern sections of the Pacific Coast, fog prevents excessive aridity that would ruin vegetation. Ina single night, such a fog has been known to deposit as much as five hundredths of an inch of water, the equivalent of a moder- ate shower. On the coast of Peru, where there is little rain, plants grow luxuriously during several months of the year, watered only by the drizzly fog of the region. A fog is essentially a cloud that is close to or touching the earth. When water vapor is condensed by chilling and made visible near the earth, it is called a fog. When the operation is carried on overhead it is called a cloud. Clouds and fogs both consist of tiny drops of water condensed around some sort of nuclei, usually dust particles. They are made up of baby rain- drops that never grow up. These are so small that they cannot fall against the friction of the air, or if they do fall, they descend very slowly. Often these water particles are only one twenty-five thou- sandth of an inch in diameter. In a dense sea fog there may be more than ten thousand of the pin-point droplets in one cubic inch. The density of the fog de- pends upon the number and size of the water particles. HAT stunts the growth of these baby raindrops? Why do they not combine into larger drops and fall as rain? A plausi- ble theory is that minute elec- trical charges on each push them apart. Similar charges of elec- tricity, either negative or posi- tive, would repel the fog parti- cles from each other and arrange them at about equal distances in space. When a warm, moist current of air meets a cold current and the moisture condenses into drops almost as small as mole- cules, fog is born. The famous fogs of the Banks of Newfound- land are created by the meeting of the cold air over the Labrador Current from the north and the POPULAR SCIENCE MONTHLY A billowy sea of fog off the California coast, photographed from above by F. Ellerman. Fog is essen- tially a cloud that is close to or touching the earth, and is made up of countless tiny water particles. warm, moist air above the Gulf Stream from the south. These fogs are so dense that one of the sea yarns of the old New England whalers told of jib booms that had been broken by bumping into a Newfoundland fog. Fog also is created through radiation of heat. During the night the air loses heat, and if it happens to be quite humid so that the air contains a lot of water, the moisture condenses on the dust parti- cles in the air to form fog. The same thing happens when a body of cold air comes in contact with a body of warm, moist air. One of the surprising things about fog blankets is that they contain so little water. A cubic mile holds scarcely a gallon. A bucket of water in the form of fog could tie up the port of New York or “London Fog,”’ a prize photograph by Dr. Maximilian Toch, F.R.P.S., showing the Thames and Houses of Parliament enveloped in mist- London and cost thousands of dollars. Were it not for the wind-borne particles of dust and soot in the air, there would be little, if any, fog. One of the causes of London’s celebrated ‘pea soup” is the soot that hangs in the air, produced from the seventeen million tons of coal the innabitants burn each year. In a London street, experts estimate, a man inhales two billion particles of soot in ten hours. Over New York City, more than 2,000 tons of dust hangs in the air, Professor H. H. Sheldon, of New York University, recently announced after making a series of measurements. F COAL fires were supplanted by some other method of heating that did not discharge unburned particles of carbon into the air, large cities would be freer of fog than the surrounding country. The heat rising from the many buildings would evap- orate the moisture. Tests have shown that the rays from glowing neon lights are more effective than ordinary white light for penetrating smoke-created fogs, in which the nuclei of the water droplets are largely floating bits of soot. For white “country fog”, in which the nuclei are particles of dust—bits of fibers, vegetable matter, and molds—white light is said to be just as effective in piercing the fog. The neon light, first produced by the French physicist, Georges Claude, in 1910 by passing an electric current through a glass tube filled with neon gas, is of especial value in guiding flyers through city fogs to invisible airports. It is one of several recent inventions which are helping prevent accidents in fog. Another is the radio beacon. It provides a path or beam of radio signals which an airplane pilot can follow by the intensity with which they are received. In the ordinary beacon, as soon as a flyer veers from the path, signals fade out. Experimental altimeters (Continued on page 158)

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POPULAR SCIENCE MONTHLY DeEcEMBER, 1929 Oil Wells Drilled in the Ocean Great Wharves of Steel Reach Out from California Shore to Tap Deposits in the Bed of the Pacific By GEORGE LEE DOWD, JR. IL from the bottom of the sea is now being pumped into reser- voirs from three unique under- water oil fields on the California coast. Huge wharves, a quarter of a mile long, reach out into the Pacific to support the derricks used in plumbing the ocean bottom for petroleum. - Within a distance of twenty-five miles, along the ceast in the region of Santa Barbara, the operators of two new fields and an old one— the famous Summerland field—-have invaded the sea in search of oil and rich new deposits have been found in the shale below the breaking surf. Geologists long have known that the remains of fish, shellfish, and mi- croscopic sea animals, buried in rock, have produced a large share of the world’s petroleum. Through the ages, the oil in these sea deposits has been concentrating into pools similar to those now being tapped. It was at Summerland, a few miles east of Santa Barbara, that the first drilling in the ocean was done in the United States. Since the railroad between Los Angeles and San Francisco skirts the beach at this point, this field is always pointed out to tourists as one of the sights of California. The most extensive portion of the new ma- rine development is lo- cated some twelve miles west of Santa Barbara and about a hundred miles from Los Angeles. In the surf paralleling the Elwood Terrace oil field, discovered a little more than a year ago, a dozen or more wharves are being built into the sea. Huge steel and con- crete foundations for der- ricks are being construct- ed to make it possible to tap the treasure of the ocean floor. Building these wharves and foun- dations was an engineer- ing problem of no mean proportions. They had to be made exceptionally heavy to withstand the shock of the hammering waves. The derrick foun- + wharves At right: caissons derrick. A view along the ocean bluff at the Elwood oil field, showing some of the wells on land, and the new extending out from shore to derricks which tap the ocean bed. Sinking steel at Elwood to form the supporting piers for the foundation of a The foundation te must withstand the bat- ™ . “- tering of Pacific storms. New The first oil well in the Pacific ocean, in the Elwood field near Santa Barbara, Calif. The derrick is 290 feet from shore. The steel wharf pictured be- low, at Rincon, Calif., extends to a point 1,600 feet from shore, where a well will be drilled. dations had to be perfectly rigid so that holes more than 3,500 feet deep might be drilled with heavy-duty machinery with- out excessive vibration and they had to be strong enough to withstand high gas pressures which might be encountered in the wells. To meet these conditions, the wharves have been built on steel piling in large H-sections, driven through the sandy bottom into the shale underneath. They are reinforced with cross braces and all joints are electrically welded. Several types of con- struction have been em- ployed in building the derrick foundations. One of these is a cofferdam structure, in which a concrete and steel island has been built around the area over which the derrick stands. Inside this a practically solid concrete block was set, founded on the shale bottom, and built to the height of the wharf floor, some twenty feet above the water. Another com- pany has constructed foundations by driving fifteen-inch circular pil- ing to form the outer wall of each of four corner founda- tions for the drilling rig, filling the center with reinforced con- crete. These corner founda- tions are seyen or eight feet in diameter. In the center, around the pipe through which the well will be drilled, a similar steel and concrete pillar has been built, but of fourteen feet diameter. The center pipe is thirty inches in diameter, and is driven into the shale as far as possible before the concrete is poured around it inside of the central pier. Still another company has sunk circular steel caissons ten feet in diameter to the shale to form the outer wall of the corner piers, and fourteen-foot caissons for the central piers. These have been filled with concrete. In each case the foundations are sepa- rate from the wharf structure so that they will not be affected by warping or weaving in heavy seas. Twenty-five miles east and south of Elwood is another marine development, in some ways even more striking. Here, in the Rincon field, a steel wharf reaches in- to the ocean to a point 1,600 feet from shore. The wharf itself is 1,888 feet long, for the portion nearest the land, 764 feet in length, is placed at an angle of about forty-five degrees to the shore line. The first well to be drilled in the water is to be at the end of the wharf, where a platform seventy-seven by 200 feet is being constructed to accommodate the der- rick, machinery, and nec- essary tanks. It will be about half a mile from et the nearest land well in — the field, just above the ak high tide line.

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@ @ om (PCD ee ee DeEcEMBER, 1929 Skillful lighting effects transformed build- ings and grounds of the International Exposition at Barcelona, Spain, into a fairyland. Compare this daylight view of the ‘beautiful National Palace with the nighttime photo reproduced at the right. Courtesy Westinghouse Electric and Manufacturing Company POPULAR SCIENCE MONTHLY Painting a Worlds Fatr Even the sparkling cascades in front of the National Palace are illuminated. From caldron-shaped vessels in the background, rising steam is made brilliant with playing light beams of many different colors. Powerful floodlights, bathing walls and towers, and ingenious indirect lighting effects, produced this artistic illumination of the royal palace, the Palacia de Alfonso XIII. A modern triumph made possible by fifty years of progress in lighting science. * A general view of buildings and grounds in the decorative lighting area of the exposition. Illuminated posts line the thoroughfare, the Avenida de America. How illuminated’ posts were constructed. _ When finished, the wheel-like supports hold circular panes of colored glass through which light shines. Illuminated fountains spout sprays of dazzling color to adorn the exposition at night. In the back- ground are seen the searchlights and dome of the National Palace. Construction of one of the illumi- nated fountains is shown at the left. The fountain itself, at the center, is surrounded by six electric lamps which send beams directly upward.

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POPULAR SCIENCE MONTHLY DEcEMBER, 1929 High Speed Skyways 14 Miles Up AST, SMOOTH WINDS GLOW IN NIFORM IRECTION Ar pe = iFFERENT LEVELS.

The recent flight of the Opel rocket plane lends timely in- terest to this scientific dis- cussion. of proposals to navi- gate the stratosphere—that bleak layer of thin air far above cloud and storm, where the stars shine as beacons and steady winds promise swift _passage over land and sea. By ALDEN P. ARMAGNAC NE mile from its take-off, a frail plane belching a cloud of blue smoke wavered to an uncertain landing near Frankfort-on- Main, Germany, a few weeks ago. It grazed the field, scudded across it at sixty miles an hour, spun around, and turned turtle. It was damaged badly. But its pilot, Fritz von Opel, had ac- complished the first flight in history in a rocket-propelled airplane. It is a Jong way from the 550-pound, gliderlike craft which Opel piloted to the massive, rocket-driven cars which some theorists predict as a future development in aviation. His fragile craft, driven by twelve rockets in a steel case behind the pilot’s seat, may—or may not—be the prototype of greater machines hurled through space by tons of explosive. Its greatest significance, in the minds of aviation engineers, is that it suggests one way in which a long-standing goal of aviation may be achieved. That goal is the navigation of the

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APES THROUGH TURBINE AND HELPS OPERATE COMPRESSOF WIND DRIVEN COMPRESSOR PUMPS AIR INTO THIRTEEN - FOOT PR OPELLER - GRIPS THIN Al © AVGiiera-th aa GE Tay Grelct FOR RADIO am € STREAM NHEEL HOL eAIR-TIGHT CABIN MAINTAINS NORMAL AIR PRESSURE Design of a high-altitude plane, as pictured by B. V. Korvin-Kroukovsky, aviation engineer. Above: The layers of the earth’s atmosphere, showing how the upper levels above clouds and storms may be traversed eventually by high-flying planes in swift passage between New York and Paris. “stratosphere,” the upper layer of the earth’s air. In that mysterious region miles above the earth, where few daring explorers have ever penetrated, the air is so thin that a human being could not live without artificial oxygen. Yet some authorities declare that the long-distance air lines of the future may be established there. Free of the resistance of air at ordinary levels, airplanes could speed across oceans and link continents at almost incredible velocity. Recent proposals have been made to fly machines at such a height and speed. A young German engineer, H. G. Perl, announced not long ago his plans for a twenty-two-foot, half-ton bullet plane which he proposed to navigate at an altitude of seven or eight miles and at a speed of more than 650 miles an hour to cross the Atlantic in six hours. An Austro-German experimenter, Prof. Her- man Oberth, proposes a rocket ship many times faster. Is there really any scientific basis for such an idea—and, if so, what sort of craft may be the one to achieve it? Today it is possible to build an airplane that will fly 60,000 or 75,000 feet high, without recourse to rockets or any such highly experimental means, in the opinion of one prominent aeronautical engineer who has worked out the details of such a craft. Other experts have endorsed the high-altitude airplane as the next logical development in air travel. <A_ great German airplane firm is said to be plan- ning actually to build high-altitude planes with air-pressure cabins for passengers. And eventually rockets and other in-

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DecEMBER, 1929 ventions may conceivably augment the range of high-flying planes. Aside from the possibility of flying to great heights, what of the great speed with which it is supposed airplanes could fly miles above the earth? Present knowl- edge of the thin belt of air that surrounds the earth—for practical purposes some twenty-five miles thick, though it trails off into nothing many miles beyond— bears out the idea. The few men who have penetrated into it more than six or seven miles have helped to find out what it is like. Capt. Hawthorne Gray, of the Army Air Corps, soared in his balloon to a height of 42,470 feet, the greatest altitude ever reached by a human being. He died when he attempted to repeat the feat. Another pioneer into the unknown region was the German pilot, Willy Neunhofer, whose altitude flight of 41,795 feet last May was a new world’s record for air planes. From such flights as these, and from the records brought back by free- flying “‘sounding balloons” of the United States Weather Bureau from heights up to twenty miles or more, it is known that the air above the earth is at least a two- story affair, and that the second level has different properties from the first. HE earth’s inhabitants live in the bottom layer, or “‘troposphere,’’ com- prising the first six or seven miles of the atmosphere. Within this thin layer occur the storms that sweep the earth and all of the turbulent winds that threaten air- craft. Ascending from sea level, the air becomes perceptibly thinner. On a high mountain, reduced pressure causes water to boil at lower temperatures. The thin- ness of the air becomes painfully apparent to a mountain climber as breathing be- comes difficult. And aviators know that, after an altitude of about 16,000 feet is reached, oxygen is required to sustain life, Belching a cloud of smoke, the Opel rocket plane roars across the field in the take-off. for at that height there is only half as much air as at sea level. With increasing height the air grows colder, until at six miles’ altitude a pilot may be soaring through frigid breezes of sixty or seventy degrees below zero. Then, if he pushes upward, an abrupt change occurs at about seven miles’ altitude. It gets no colder; perhaps a little warmer. There are no storms, no clouds—he has left them far below. Where he has climbed, there is always sunshine. A sky of a weird, deep blue in which the sun shines almost like the moon at night, tells the oxygen-breathing pilot that he is in that sunny, frigid, mysterious region POPULAR SCIENCE MONTHLY known as the “stratosphere.” e Up there at the top of the sky the air is so thin that it hardly supports the plane’s wings. The motor, despite the “supercharger” that pumps compressed air into it, literally gasps for breath. But con- struct an airplane that could operate efficiently at such a height, and there is almost no limit to the ; forward speed that it might attain. The backward drag of air rushing past wings and fuselage has all but disappeared. Moreover, smooth winds of great speed are known to exist at high levels, and these might be used to - | advantage by a high-flying airman. Sounding balloon observations made from a weather station near the Official Photozraphs U. S. Army Air ( orps The door of the air- plane pressure chamber which almost became Macready’s coffin equator revealed a power- ful east wind between the altitudes of eight and eleven miles, which might add sixty miles an hour to the speed of an airplane flying from Europe to America. In the next three miles upward a strong west wind was which traveled a mile in the first rocket-propelled flight in history. ~ ae xe OO Ma : 7) Equipped to climb the sky. Lieut. John A. Macready, veteran high- altitude pilot, wearing feather- lined suit, oxygen mask, and goggles treated with antifreeze. found. Above, the direc- tion was again reversed. Thus regular air lanes might be established at various levels, wherever the wind was found to be most favoring. Flying at 70,000 feet, say, a pilot could glide with motors shut off to a landing as far away as 300 miles. It would take him more than an hour to come down. In case of trouble at sea he could radio to the nearest steamer and land alongside or near it. At that height he would always have a cloudless sky for his astronomical observations. ILL such high-altitude air lines soon replace infrequent, courageous dashes into the upper atmosphere? Some experts think so. They agree that air- planes of new but some- what conventional design are likely to be the first to ply such lofty air lanes and that rocket or other- wise propelled craft must follow later if at all. Not long ago Igor I. Sikorsky, famous plane designer and builder, predicted in Pop- ULAR SCIENCE MONTHLY a “new type of airplane with highly supercharged motors and an inclosed cabin with air kept under approximately normal pressure, to permit flying at high altitudes with speeds of say 400 to 500 or more miles an _ hour.” (P.S.M., June ’29, p. 125.) Leaders in other fields, among them Prof. Albert Einstein, German relativ- (Continued on page 155)

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LPAI: DecEMBER, 1929 POPULAR SCIENCE MONTHLY Prof. Vernon Jones, Clark University.“ Few agree whether an act is right or wrong.” Prof. Joseph Jastrow, New York, ‘Criminal records may be expres- sions of mental states.”’ Dr. James R. Angell, President of Yale University. ‘Yale plans to establish an ape farm in Florida.’’ Why Minds Behave As They Do “The motions of the solar system since its beginnings are less compli- cated than the play of a child for a day,” said James McKeen Cattell, presiding over the recent International Congress of Psychology at Yale. Here are presented outstanding experiments and discoveries concerning the riddles of human behavior, as reported to the Congress. Sree LOSELY following the recent sessions of the International Congress of Psychology at Yale University came the announce- ment from Washington, D. C., of the first step toward establishing a national center of research in problems of human and animal psychology—the Nat- ional Institute of Psychology. The incorporators of the Institute were Professor Knight Dunlap, head of the psychology department of Johns Hopkins University; Dr. Hugh S. Cumming, Sur- geon General of the United States Public Health Service; and Dr. Edwin E. Slos- son. Its purpose, as stated by Professor Dunlap, is to establish a national psycho- logical laboratory to “undertake pro- grams of research too long, expensive, and complicated for other institutions.” Following are some of the year’s out- standing discoveries in psychology, as re- ported to the International Congress. Secrets of Happiness NTELLIGENCE has nothing to do with happiness, reported Prof. Good- win Watson, of Teachers College, Colum- bia University. A test he gave 400 stu- Prof. L. M. Terman, Stan- ford University. “ Marriage feminizes a man’s mind.”’ Dr. H. M. Johnson, Mellon Institute. “Sleep curled up like a kitten.’’ dents showed fifty of them happy, and supplied data from which Professor Wat- son presented a picture of the typical happy person. Such a person is likely to be a man, and married, the experimenter said. He is above the average in health, active in social life, and confident that he can tell a joke well, lead a discussion, act in a play, or direct a group of workers. His home is harmonious, he enjoys his job, and he is fond of adventure. Factors besides intelligence which ap- parently have nothing to do with being happy are nationality, race, physical dis- abilities, financial situation of family, and ability to swim, play baseball, paint, write poetry, or draw. Measuring Personality ees HAT elusive quality, “‘it,’’ otherwise known as “personality,” can now be defined and measured, Prof. Mark A. May, of Yale University, told the psy- chologists. It is the effect upon others of an individual’s physique, his dress and manner, the quality of his voice, and his choice of language. All these may be rolled into one, termed Dr. A. A. Brill, New York City. ‘‘ Psychoanalysis helps strange mental cases.”’ Dr. Coleman R. Griffith, Univ. of Illinois. Studies acrobats by movies. his “social stimulus value,” and given a rating from zero to one hundred percent. For instance, a person who can enter a room without attracting the slightest rec- ognition of his presence from others, by word or glance, rates “zero” on the per- sonality test. He simply does not count. How to Sleep LEEP curled up like a kitten, and not stretched out like a ramrod. That was the advice of Dr. H. M. Johnson, of the Mellon Institute of Industrial Research, after investigations that disclosed star- tling differences with the teachings of phy- sicians. The greatest possible relaxation, he said, is in a coil resembling a kitten’s, or a sprawling posture like that of a swim- mer. A badly designed or narrow bed limits the number of possible changes of position—and a typical individual shifts his position thirty-three times in a night, the studies revealed. Children take three times as long to go to sleep as adults, Dr. Josephine C. Fos- ter, of the University of Minnesota, re- ported. On the average they require twenty minutes for slumber. City chil- dren have longer sleeping hours than Prof. Harry Elmer Barnes, Smith College. ** Abolish modern juries.”

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DECEMBER, 1929 country children, according to her records. Slight preferences for cer- tain sleeping postures were described by Dr. M. Adelia Boynton, of the University of Minnesota. In general, children prefer to sleep on the stomach rather than the back, and a still greater number prefer sleeping on one side. They are likely to sleep on the right side if left-handed, and vice versa. A room ex- cessively hot or excessively cold is unfavorable to sleep. Violet ray treatments as a possible agent of sleep are be- ing investigated, Dr. C. R. Garvey, of the University of Minnesota, reported. Behavior Studied by the Movies OVING pictures of acro- bats swinging on tra- pezes and being thrown in the air from one to another were described by Dr. Coleman R. Griffith, of the University of Illinois. He took the pic- tures, at four times normal speed, to show the men’s muscular coérdination and their expression of fear. Their bodies were marked so that the position of their limbs at each moment could be meas- ured on the photographs. A demonstration of the way that mo- tion pictures can be used to portray vivid- ly a scientific theory was the exhibition of the six-reel film, Mechanics of the Brain, prepared abroad by the dean of Russian psychologists, Prof. Ivan P. Pavlov. Ba- bies, monkeys, dogs, and even trocodiles and elephants were actors in this six-reel film, in which Professor Pavlov had crowded the results of his life work of ex- perimentation. It portrayed the develop- ment of the “conditioned reflex,” that psychological mechanism that makes people come to the table when they hear the dinner bell, or halt at a traffic inter- section when lights are red. A baby was shown being taught to open his mouth for a biscuit when he felt the slight pressure of an inflated bag strapped on his arm. This is accomplished by an ingenious machine which drops a biscuit into the child’s mouth and at the same time applies the arm pressure when the experimenter presses two bulbs simultane- ously, as shown in accompanying illustra- tions. After the opera- tion has been _per- formed repeatedly the child will respond to a squeeze on the arm by opening his mouth for a biscuit, even if none appears. Another scene en- abled the psychologists to watch a trained monkey climb from its perch for food at the sight of a red disk, but remain unconcernedly scratching its head when a blue disk was Prof. Wesley R. Wells, POPULAR SCIENCE MONTHLY ‘EXENA YCMBBHOrO a> lt Bei Courtesy Amkino Corporation Diagram showing how “conditioned refiex’’ is formed. A view of a revolving disk and an electric shock on the foot impress themselves on the brain simultaneously. If repeated, this forms an association which causes the dog to jump, as if shocked, at sight of whirling disk. substituted. With the aid of pictures and animated diagrams, Professor Pavlov showed that a sort of “short circuit” in the brain is established by the constant association of two such impressions as Dr. Mabel Ensworth 29 sight and taste received simul- taneously by the senses, and that the resulting automatic response in human beings or animals can be created or abolished at will. New Knowledge of Dreams REAMS of falling are caused by a slight drop of some part of a sleeper’s body, when he unconsciously shifts in bed. This discovery, reported by Prof. D. B. Klein, of the University of Texas, was made while he was trying, with the aid of hypnotic sleep, to find what made subjects dream. When Professor Klein sharply depressed the foot of a cot where a hypnotized girl was lying, she told him she was dreaming of falling down a “chute-the-chute,” feet first. A young man whose pillow was pushed down to the left of his head said he was falling into a cellar, head downward and twirling to the left. The experiments also throw new light on the du- ration of dreams and the frequency of certain kinds, and suggest that dreams may be controlled at will. When a person wakes with the consciousness of an exquisite melody he heard in his dream, he need not struggle to recall it—for he can’t! It never really existed, Prof. A. A. Roback, Boston, Mass., lecturer, de- clared. He suggested that the mind of a dreamer supplies desired romance by pre- tending to reveal something wonderful, but guards its own “respectability” by covering the deception. A person dreams, for instance, that an important inscription is to be unveiled to him—but the letters are scarcely visible. If he is too curious about it, his mind deliberately wakes him up—and he feels that only poor eyesight has denied him a marvelous vision. Actual cases where composers, mathe- maticians, and poets have received great inspirations in their dreams are rare, Pro- fessor Roback declared. Shadowland of the Mind ANE persons may have hallucinations when they are overtired, said Prof. David Slight, of McGill University. The most frequent are strange “visions” which disappear on taking a sedative drug. The “white comrade,” a ghostly specter reput- ed to have been seen by World War soldiers moving among the wounded on battle- fields, was called an il- lusion by Dr. G. B. Cutten, president of Colgate University. Syracuse University. “Critical persons are easiest to hypnotize.’’ Goudge, Chapel Hill, N.C. Prof. D. B. Klein, * Physicians and psycholo- University of Texas. P robably the specter gists should work together.”’ He can make a sleeping was suggested by the person dream of falling. (Continued on page 148)

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Spas: erat see ‘ a age Soar POPULAR SCIENCE MONTHLY DECEMBER, 1929 Welding—The Silent Builder How Fiery Torch and Electric Arc Are Replacing the Din of Riveting in Modern Metai Construction ELDING may be substituted for riveting, bolting, or other requirements prescribed in the Building Code of the City of Pittsfield.” So reads, in part, the new law of Pittsfield, Mass., first city in the country to adopt formally the American Welding Society’s proposed code introducing noiseless erection of skyscrapers. Pittsfield is not alone. In. forty-five cities of the South and West, led by Sacramento and Alhambra in Cali- fornia, the Commissioner of Build- ings may now grant permits for welded instead of riveted structures. The legislature of Pennsylvania has passed a law that permits all first- class cities of the state to use welding in erecting buildings. In Chicago, union riveters are taking lessons in the new process, and everywhere cities are becoming interested ina real reform made possible by scientific advance. Din, constant and unmerciful, long has been accepted as the inevitable evil of a skyscraper “going up.” Behind the rat-tat-tat of pneumatic riveting hammers surges the force of compressed air at 100 pounds’ pres- sure to the square inch. The average skyscraper requires the placing of 80,000 to 100,000 rivets. Health commissioners deplore the noise as one of the most nerve-racking of great cities. Experts say, “There is no way to silence the sound created by the irapact of hammer and rivet.” Silent, welded construction is fast making the rivet obsolete. By “gluing” girders together with molt- en steel, the welder dispenses with rivets entirely. Tests have shown By ROBERT E. MARTIN conclusively that a welded joint properly made is as strong as the metal it joins or stronger. Hence it has an immediate advantage over riveting. A riveted joint actually weakens the metal by the rivet holes drilled in the beams. Broadly speaking, welding is the proc- ess of bringing metal pieces together in a semi-molten plastic condition so that they will fuse and form a joint. Few Cutting and welding steel plates on a ‘ship’s bottom in a Hoboken, N. J., dry dock—a night photo. persons realize the important part that welding plays in their daily lives. With- out the blinding, sputtering arc of the masked electric welder and the hissing flame of the begoggled blowtorch opera- tor, many modern conveniences would be impractical. Automobiles and gas stoves, refrigerators and andirons are welded. Hot-dog grills and oil-burner tanks, billiard-table legs and radio vacuum tubes owe their perfection, if not their very ' existence, to the welding art. It has supplied inexpensive and durable metal furniture for homes and offices. The jeweler with a tiny bit of gold or silver to be fused, and the shipbuilder with the broken rudderpost of a giant steamship to be mended, are alike interested in welding. Improvements and new applica- tions follow almost daily. A process of spraying a wear-resisting alloy on the tips of plowshares and oil-well drills has been found to increase their life from three to five times. Apparatus for a new type of welding torch that combines the flash of the electric arc with the searing chemical heat of hydrogen gas in a peculiarly active form has been placed on the market. Invisible infra-red light has been used to take pictures of the molten metal to reveal better ways of welding. But the outstanding de- +t Arc welded girders were bent by a 7 hurricane which wrecked this Florida building, but the welded joints held firm. Right: Close-up views of arc welding taken by infra-red light.

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DEcEMBER. 1929 velopment in welding is its substitution for riveting in putting together buildings, boats, machines, and bridges. Although it was only three years ago that construction began on the first large rivetless steel building in the world—a five-story factory for the Westinghouse Electric and Manufacturing Company at Sharon, Pa.—a recent report of the General Electric Company lists sixty-five buildings, of from one to twelve stories, erected by electric arc-welding alone. Gas welding recently put up a new one-story research building at the Niagara Falls, N. Y., plant of a carbon products firm. When a towering, 134-foot addition to the power house of a hotel in Atlantic Fxperts of the United States Bureau of Standards test- ing the strength of welded joints of airplane fuselages. City, N. J., was erected by welding re- cently, some of the guests were unaware that work was in progress—and none was disturbed. Electric welding made possible the noiseless erection of some of the heaviest types of steel shapes used in building construction. The proprietor found that silence paid in dollars. His hotel operated at full capacity during the addition. A hospital at Wheeling, West Virginia, added another story to a part of its building recently by arc-welding. Fifteen feet from a table where surgeons were operating, a welder struck an arc and silently fused great beams to steel columns. The record for steel tonnage in a building put up by the arc-welding process is probably held by a recent addition to the West Philadelphia, Pa., plant of the General Electric Com- pany. It contains 1,000 tons of structural steel. That welded buildings are no longer an experiment, but a complete success, was the report of Prof. T. R. Lawson, of the Rennselaer Polytech- nic Institute, last June, after two years of exhaustive lab- oratory tests of arc-welded building joints. In August a small hurricane put his asser- tion to the test. It hit a large packing house being erected in Florida by arc-welding. Two walls of masonry blew out, and crashed down upon the welded steel members. These twisted and buckled, but the welded joints held firm under the impact. Buildings are not the only structures to benefit by weld- ing. In March of last year, what is said to be the world’s POPULAR SCIENCE MONTHLY Welding a steel column for the new Pacific Mutual Building in Los Angeles, Calif.— an example of noiseless construction. first arc-welded railroad bridge was opened to traffic, at Chicopee Falls, Mass. Experts estimated that a third less steel had been used than ordinarily would have been required, since the steel members were not weakened by rivet holes. A new 6,000-ton German cruiser, the Koenigsberg, is called the first cruiser to be all- electrically welded, the process saving about fourteen percent in weight. All new German destroyers, two cruisers, and a 10,000-ton battleship which is now under construction are to be electrically welded, it has been announced. Three arc-welded steel motor- boats, each twenty-eight feet long, built by Army engineers for use as carriers and towboats, have com- pleted a year’s service on the Mississippi River, and three more have just been added to the fleet. A 277-mile pipe line to deliver gas from Rock Springs, Wyo., to Ogden and Salt Lake City, Utah, is one of the latest of giant tubes Welding is used increasingly in the fabrication of huge industrial machines. Here a workman is welding the steel frame of an electric generator. 31 to be arc-welded. Welding builds the world’s airplanes, and of late has been increasingly used in the fabrication of industrial machinery, such as electric generator frames. Still another applica- tion is the use of welding to restore worn trolley car wheels by building up the worn parts, a process also applied to worn rails. Railroad ties have been fabricated by welding from battered pieces of railroad track that had been discarded. NOVEL process depending upon weld- ing is the application of wear-resist- ing alloys, notably an exceedingly tough material known as stellite, to tools that undergo rough usage. A rod of the alloy is held over the tool and a blowpipe flame applied to it sprays molten metal on the tool. The hard coating thus formed pro- longs the life of the tool as much as three to five times. This process has been ap- plied particularly to oil well drilling equipment, cement mill machinery, quarry tools, and agricultural implements. Research on welding problems is aided by the recent discovery that the operation of welding may be photographed to new advantage by the invisible rays of infra- red, or “black” light. Experimenters long had desired to see at close range the action of different welding rods and “‘fluxes’’ used with them to control the flow of metal. But in the tiny quarter- inch cube of space at the tip of a welding rod five horsepower of heat energy is **Atomic hydrogen’”’ welding torch invented by Dr. Irving Langmuir, noted physicist. It combines an electric arc and a hydrogen jet. generated, and so brilliant is the light emitted around the arc and flow that it seemed impossible to observe them. A blurring glow obscured the flow of metal even when it was observed through black glass. Just when experts were ready to abandon the problem, a method used to take long distance photos from airplanes was applied to welding by a Rochester, N. Y., camera firm work- ing with a Chicago metal concern. In this method (Continued on page 151)

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When trees become torches—a fire at night in Columbia National Forest, Washington. WENTY dollars a minute is the average sum our Gov- ernment must spend, year after year, to combat forest fires. Fire can destroy in a week as much timber as lumbering companies can cut in a year. In 1928 forest fire damage totaled $82,934,000. There were 177,362 fires, of which 40,579 were in the protected area of federal forests and national parks. Altogether 43,931,000 acres were burned over during the year. For 1929, United States Forest Service officials estimate that all of these figures will be doubled. Because of nation-wide dry weather this has been the worst fire year since the disastrous western fires of 1910. If the estimate turns out correct, the Red Menace this year will have cost the United States more than $160,000,000 with nearly one hundred million acres of land burned away. A terrific damage. Experts agree that something must be done to stop the waste, but what? If science can help fight forest fires in other ways besides those now used, Forest Service officials say they will be delighted to know them. So far the ran- gers and the “smokechasers,” or guards, have cal found nothing to stop a crown fire —one that leaps from tree top to tree top—except a drenching rain or for the fire to burn itself out, and nothing better for a duff or undergrowth fire than trenching and backfiring. The Forest Service has tried chemicals, but chem- icals are useless unless the fire is confined where they can blanket the flames. It has tried airplanes, but air- planes cannot reach the source of undergrowth fires, At right: A spectacular night photograph showing the line of a brush fire descending a mountain side north of Santa Paula, Calif. The duff hygrometer for measuring moisture in ground debris. Above: The sling psychrometer for recording humidity, used by rangers to forecast forest fire weather. POPULAR SCIENCE MONTHLY Can Science End Forest Ftp Sir. Ae = Sighting a fire with alidade and map in the Striped Peak lookout station, Coeur d’Alene National Forest, Idaho. and in a crown fire the heat is so intense that the planes cannot approach close enough to aid. Science, however, has contributed valuable warning instruments to the fire fighters. Chief among these are the sling psychrometer, for recording the humidity of the atmosphere, and the duff hygrom- eter, for indicating the percentage of moisture in the ground debris. The sling psychrometer, which every ranger is taught to use, consists of two thermom- eters, one wet bulb and the other dry. The ranger swings this through the air for a few seconds, reads the mercury in the two thermometers and, by com- paring the readings with a printed scale, is able to determine the relative hu- midity of the air. The duff hygrometer resembles a gage on the end of a long hollow spike, dot- DerEcEMBER, 1929 1 Bes Ep x er: . os { | * * Digging a fire-line trench to save heavy timber in Pike National Forest, Colorado. ted with holes. This spike is inserted in the ground debris—pine needles, leaves, and so on—and an expanding and contracting rattan coil registers the moisture percentage. Studies conducted by Forest Serv- ice experimental stations have shown a humidity of twenty-five percent, or lower, highly dangerous, and of sixty percent, or above, safe. Below twenty-five percent is a con- dition ripe for a crown fire. Similar experiments have shown that when the topmost layer of duff has less than ten percent moisture, any source of ignition producing the same heat as an ordinary match can raise the duff to the kindling point. At less than seven per- cent moisture, the duff may be freely ignited by locomotive sparks or a glow- ing cigarette butt. At twenty-five percent the duff is generally safe from any of the common causes of forest fires, except possibly lightning. One lightning storm has been known to start as many as 400 separate forest fires. For quick and accurate locating of fires, the rangers use movable sights mounted on flat maps in the lookout towers. These are known as alidades. When a fire breaks out the readings of the alidades sighted on the fire from separate towers are reported by telephone to-the supervisor’s office, where the exact location of the fire is determined by simple triangulation. Careless people cause most of the forest fires. Out of 40,000 recorded in the protected area last year, 8,346 were caused by dis- carded cigar or cigarette butts and 3,681 by neg- lected camp fires.

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DecemBen, 1929 POPULAR SCIENCE MONTHLY As symmetrically beautiful as snowflakes Lightning’ s power transmission lines, recorded by the klydonograph. Above is a camera record of a negative surge of lightning. Ff ingerprints John F. Peters, inventor of the Westinghouse klydonograph, an ingenious eight-day camera which gathers evidence of the nature of light- ning by high speed photographic records. He is shown here with an early model of the device. A positive surge of lightning. Study of the lines reveals the peak voltage of the lightning stroke, how fast it grew, polarity, and direction of travel. The latest type of klydonograph, with , 4 A lightning bolt’s autograph in the form of a eight-day film. Lightning acts in a few ’ ring. By studying its characteristics revealed millionths of a second, but this instrument A klydonograph station under a transmission by the size, intensity, and arrangement of lines, has photographed artificial surges which tower. It stands on guard day and night scientists hope eventually to find ways of com- lasted less than ten billionths of a second. to record thunderbolts that cripple power lines. bating the destructive effects of lightning.

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OG OPT A 4 34 POPULAR SCIENCE MONTHLY Decemser, 1929 ack to the Stone Age ina Modern Xa ent cers. 5 > 4 New Hebrides natives swarming about the Ji//yria in their frail dugout canoes. Left: A fierce warrior of the Upper Sepik River in New Guinea. He posed only after the promise of a steel knife. N FAR-OFF islands of the Pa- cific, north of Australia, live savages in conditions as primi- tive as those of the Stone Age. Many never had seen a white man until Sathahedatineen arettbetn tes visited by the expedition of scientists found only in the Celebes Islands. which obtained these photographs. On a 30,000-mile cruise in the yacht Illyria, owned by Cornelius Crane, of Chicago, this expedition obtained specimens for the Field Museum of Natural History. The natives pictured inhabit the islands of New Guinea, Celebes, and the Solomon and New Hebrides groups. Resembling Alaskan totem poles, carved figures stand at a native shrine, where sacred boar tusks are kept. A hornbill, one of the strange birds captured alive by the expedition. The female sometimes is imprisoned in a hollow A typical New Hebrides bush native tree nest and fed by its ready for combat. A few days before mate through a_ hole. this picture was taken, Crane and a A war dance by bush natives of Espiritu Santo Island. Although a war was in small party visited a village of canni- progress when the Crane expedition arrived, the party received friendly treatment. bals who never had seen a white man.

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DecemBER, 1929 POPULAR SCIENCE MONTHLY 35 The exploring yacht J//yria on the Sepik River, 400 miles into the heart of New Guinea. From this point the party ascended the Mai River in small boats, reaching a wild district where the natives, still living as did our ancestors of the Stone Age, threatened them with spears and arrows until pacified by gifts. What the better dressed natives of New Guinea wear when fixed up in their ‘“‘Sunday best.’’ This party paid a friendly visit to the J/lyria. Note the nonchalant manner in which one woman is lighting her pipe. The elaborate figurehead of a na- tive war canoe, made as hideous as possible to terrify the enemy. The designs are moth- er of pearl inlay. Trading with New Guinea savages on the Upper Sepik River. Cornelius Crane. sponsor of the cruise, stands at the left. The natives would sacrifice anything but their wives for articles made of steel. This Wogumasch chieftain barred > the party from landing, fearing they would carry off the women. Women of Sowa, Ysabel Island, staging a dance which is part of their tribal A study in contrasts. Sidney N. Shurtleff, of Boston, photographer for the rites. Those white heads that are so conspicuous are the result of bleaching, for expedition, with five chiefs of the bush tribes dressed in full regalia at Ma- even in the Solomon Islands it appears that gentlemen prefer blondes. lo, New Hebrides. They bartered ancient carvings and sacred boar tusks. mal aie is scm he =a ina hme (RE em A ean. eat nal eee

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One of the most ingenious of Na- ture’s devices for seed distribution is found in the Ecballium, or squirting cucumber. Its seed case is fashioned as a sort of hydraulic gun. When the fruit is ripe. it bursts from the stalk and violently shoots out its tiny seeds, some- times to a distance of thirty feet. The young stonecrop all settled in a safe crevice after its tumble down the hillside. Here it begins to grow, mean- while drawing its water supply from the fallen leaf of the parent plant, to which it is still firmly attached. POUPLAR SCIENCE MONTHLY Nature’s Seed-Sowing Machines baal} tronal's The seeds of the burdock steal a free ride. The see.i case is armed with clinging hooks by which it attaches itself to any man or animai passing by. Here a sleeve, brushing against a burdock plant, has picked up a bundle of seeds for distribution. ee te if a - ee Se ey, These three photos show the re- markable way in which the para- chute seed case of the goatsbeard lands the seeds in a suitable spot for growing. The parachute opens tosun- shine (left) and closes with dampness (right), When it sails over a damp spot, good for growing, the parachute closes and sinks toearth. Ifit strikes an unsuitable spot, the alternate ac- tions of sun and dew, opening and closing the parachute, make it creep along until it reaches ground that is good for sprouting purposes. DrcEMBER, 1929 Attached to a falling leaf from its mosslike parent, the tiny young stonecrop bounces down the hill- side, as pictured here, until it reaches a suitable cranny for its home. The leaf acts as a cushion during its tumbling journey, in which it encounters crevices not attainable in a_ straight fall From a film in Britiah Inatruc- “Secrets of Nature” Series The seed of the thistle is shot to earth like a bomb. The seed case, floating on its feathery parachute, contains an elastic ring into which part of the seed fits. When it hits a tree, as above, the ring contracts, expelling the seed.

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asi a? DecemBen, 1929 POPULAR SCIENCE MONTHLY 37 CLIMBING to the World’s Roof Tops he? 4 Pe ~~ > SY yw’ ‘ PRY ‘wat’ s Plt Lew td ee yaa.

Members of a Russo-German scientific expedition descend- ing the treacherous ice of Fetschenko glacier, fifty miles long, which they discovered recently in the wild Pamir mountain region of Turkestan.

*- A view along the “roof of the world”’ in Central Asia. Pick- ing their way along a carpet of jagged ice, members of the Rus- so-German expedition are seen advancing toward the highest peaks of the Pamirs, the great- est of which rises 22,000 feet. Left: Mountain = climvers viewing the roof line of the Sierra Nevada range from an observation platform in Se quoia National Park, centrs! California. Among these snow-capped peaks rises Mount Whitney, 14,502 feet high, the loftiest mountainpeak in the United States proper

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38 POPULAR SCIENCE MONTHLY DrEcEMBER, 1929 Science and Tragedy in the Arctic ERE are pictured the adventures of two recent ex- peditions into the Arctic. One was a walrus hunt to obtain specimens for the Field Museum, Chicago. The other was an ill-fated attempt by a Norwegian fish- ing fleet to break a path through the ice for seal hunters. From a lookout post in the rigging of ‘the Dorothy, George Coe \ Graves II, one of the leaders of the Field Museum hunt, searches the ice for polar bears and walruses. , \ \_ Yn \ \ A polar bear caught by the Field Museum hunters and hauled by block and tackle aboard the scHooner Dorothy. Members of the crew of one of the Norwegian vessels with bear cubs they captured on the ice north of Spitsbergen. Bruce Thorne, co-leader with Graves in the Museum expedition, with his first polar bear, a huge animal nearly 11 feet long. The Quest, flagship of the Norwegian fleet, locked in the Arctic ice. Of ninety vessels which attempted to open a lane for seal hunters, about half were sunk or crushed. Many lives were lost. One of the Norwegian fishing vessels hemmed in Three beby seals, four weeks old, sun- by ice. The ships which survived the impact ning themselves on Arctic icebergs of the drifting ice returned to Norway heavily snapped by Daniel Troutwein, pho- loaded with bears, seals, and other Arctic game. tographer of the Norwegian fleet.

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DeceMBER, 1929 POPULAR SCIENCE MONTHLY 39 A black seal fast asleep on a sunny ice cake and entirely un- aware that its picture was being taken at close range. These land and water mammals are hunted for fur, hides, and oil. A desperate moment in the battle with the ice. The crew escaping from one of the foundering Norwegian vessels, crushed in the grip of the Arctic. About fifty men of the crew of 300 in the fishing fleet were lost. The Quest plowing through the tumbled masses of ice. At times progress was impossible. The expedition, financed and directed by the Norwegian government, was forced to abandon the attempt before reaching its goal. Two fine specimens of walrus obtained for the Field Museum of Natural History in Chicago by its Arctic expedition. The hunters found it necessary to kill them instantly with the first shot; otherwise the wounded tuskers would slip into the water and quickly vanish. A group of walruses awakened from their daily hap on the ice. The Museum hunters ve found them very numerous this year, sev- ae eral thousand being seen. A full-grown male ~~ —‘ tusket measures ten to eleven feet in length. Two of the Norwegian hunters dragging captured seals back to their ship across the sea of jagged ice. This remarkable photograph gives an idea of the desolate expanse of the Arctic into which the fleet of Daniel Troutwein, the photographer and radio vessels plowed their way in search of the big game of the Far North. operator of the Norwegian expedition, holding a baby seal which he captured on the ice. nea I Wate ae i EA ES SAR REL neni OE

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40 POPULAR SCIENCE MONTHLY DeceMBER, 1929 Keeping Pace with Aviation | The “Tandem,” latest creation of Giuseppe M. Bellanca, famous airplane designer. Two engines, each of 400 horsepower, are mounted in tandem in front of a short, stubby fuselage. One drives a two-blade tractor propeller in front; the other, a three-blade pusher propeller behind the fuselage, One of two huge 30-passen- ger Dornier flying boats as- sembled at the Philadelphia Navy Yard for the Stout Airlines. It is 80 feet long with 90-foot span, and is pat- terned after 100-passenger Dornier flown in Germany (P. S. M., Oct. ’29, p. 45). A new type of parachute flare for use in night landings on water con- sists of a small, powerful light oper- ated for about an hour by a tiny battery. Acork base keeps it afloat. Members of Los Angeles County Forestry Department, Cali- fornia, inspecting smoldering cigarette and cigar butts dropped from a plane in tests to determine if aviation increases for- est fire hazards. Sixteen of thirty stubs were found burning. Flying tied together. A remarkable formation exhibited by the * Aerial Armada” from the U. S. S. Saratoga, crack acrobatic sauadron of the United States Navy. Stout ropes join the planes

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DecEMBER, 1929 POPULAR SCIENCE MONTHLY 41 Radical Changes in Plane Design— A New Safety Parachute— A Speed Record, Six Miles a Minute TARTLING departures in airplane design have recently challenged the supremacy of the conventional modern aircraft. Strangest among them, perhaps, is a monoplane which recently took the air at New Castle, Del., and which appears to have been shorn of most of its fuselage. It is the latest contribution to aeronautics of Giuseppe M. Bellanca, famous airplane designer and manufacturer. As pictured on the opposite page, outriggers from the wings support the tail in a manner reminiscent of the primitive planes of twenty years ago. A tractor propeller in front and a pusher propeller in back propel it. The design is said to provide great load capacity with unimpaired maneuverability. Two short wings in front and two large ones in back distinguish a remarkable “tandem” plane invented by George Fernic, of Staten Island, N. Y., and re- cently flown successfully for twenty-two minutes at Roosevelt Field, N. Y. It is designed to carry eight passen- gers, and its inventor claims a cruising radius of 6,000 miles. Another queer plane, built by a Cleveland, O.; designer, enables a pilot to alter the curvature of the wings in flight. A New Parachute N 1TSefforts to improve the safety of aerial devices, the Materiel Division of the Army Air Corps has evolved a new type of parachute. In mate- rial, size, and principle of oper- ation, the new ’chute is exactly like the old. Instead of a circular mainsail, however, it has a triangular one. This triangle is rounded at two corners, while the third is sheared straight across. Al- though the new ’chute has twenty-four shroud lines, spac- ed about a yard apart, none is attached to the sheared-off corner, so that when the ’chute is open this corner forms a tail- like vent through which the air escapes. This gives the ‘chute a forward motion at about three or four miles an hour. It can be steered by manipulation of the shroud lines. A second vent, circular in shape, at the apex of the mainsail, is fitted with a valve that opens automatically when the parachute opens, thus re- ducing the shock on the jumper. A radical change has been made in the construction of the pilot ’chute which opens im- mediately when the rip cord is pulled and draws the main ‘chute along with it. Instead of resembling a miniature um- brella, as does the standard type when inflated, the new pilot ’chute looks like a box The parachute opened, with pilot ’chute attached. the apex is an air vent which . opens automatically to break , the shock for the jumper. with four compartments. The partitions project about fifteen inches over its edges. They are four right-angled triangles sewed together at a common perpendicular at right angles to each other. Thus, when opened, it resembles four small parachutes joined together. Though the triangle parachute has not vet been officially adopted by the Army How the new triangular parachute is folded in its pack- The pilot ’chute, divided by partitions is at the right. At if The ingenious triangular design of the four partitions which divide the pilot ‘chute into four separate compartments. Measuring the flowing qualities of sample liquids in the United States Bureau of Standards, in laboratory tests to find a new fluid which, when used in airplane compasses and inclinometers, will with- stand the extremely low temperatures encountered at high altitudes. Air Corps, about a dozen live jumps have been made with it and over a hundred “dummy” jumps. Six Miles a Minute! ASTER than any human being ever traveled before, Squadron Leader A. H. Orlebar, British flying ace, re- cently whizzed over a Calshot, England, flying course of nearly two miles at 368.8 miles an hour—more than six miles a minute! This was the official figure which was averaged with his time on three other laps to obtain the average speed for the course according to international rules. The result, an average of 355.8 miles an hour, he surpassed two days later with a new average, of 357.7 miles an hour, a world speed mark. At the speed of his record lap he would require less than nine hours to fly from New York to San Francisco. So completely streamlined was the blue-and-silver Supermarine S-6 seaplane in which he flew that even the many tiny bracing wires were shaped in profile in order to afford the least possible resistance to the air. Aviation experts point out that the speed of airplanes has increased by 326 miles an hour in the last six- teen years. In 1913 a speed of forty-two miles an hour was fast enough to win an _ international race. Today Louis Bleriot, first pilot to fly across the English Channel, predicts a speed of 750 miles an hour by 1939. is. Latest Air Words UR hours after I enplaned in Buffalo, I deplaned in New York.” Such sentences may be common in conversa- tions of the future. Two new flying words growing out of air transportation are to be in- cluded in the latest edition of the New Standard Dictionary. They are “enplane,’ meaning to board a plane, as “‘entrain’’ means to take a train, and “de- plane,” meaning to alight from a plane. Novel Equipment VERHEAD control sticks and superchargers for commercial planes are among the novelties revealed by a survey of recent advances in American airplane equipment. The joy stick suspended from above is a feature of a new tri- engined, six-passenger cabin monoplane. Its Detroit, Mich., manufacturer plans to equip [I LE I TE ET a oS fhe lit ; { : a 7 oH

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1h | {| i / 42 future models with an overhead control of wheel type. Superchargers, power- boosting devices hither- to employed almost sole- ly on planes seeking alti- tude records, are now perfected for commer- cial use. One type Is expected to be installed in twin-engined amphib- ians produced by a Cleveland aircraft firm. An open “office” plane for flying -business executives is equipped with a sliding windshield that can be drawn out to cover the cockpit and permit the handling of papers. It is a companion to cabin planes equipped with desks, typewriters, and dictaphones, made by several firms. Landing wheels that fold into the body during flight to decrease wind resistance are features of several new models. Gear- ed engines have appeared. A recent inno- vation is an “air wheel,” a wheel for planes that consists of a huge tirelike pneumatic ball pierced by a tiny hub. It combines wheel and shock absorber. A Shield from Lightning GIANT gas bag with a “wire fence” surrounding the basket marks the latest advance in balloon design. The hanging wires are intended to act as a protection against flashes of lightning. This lightning shield was invented by Ward T. van Orman, famous aeronaut, who piloted the new balloon in the Gordon Bennett Trophy Race. It is called the Goodyear VIII, and repre- sents seventeen years experience on the part of the company constructing it. Few major improvements have been made in the balloon since 1783, when the French scientist, Professor Charles, made his first ascent. The ripping panel, allowing the bag to be emptied speedily upon landing, and the drag rope, keeping the balloon at an even altitude, have been the two most impor- tant innovations in balloon construction in the last 150 years. If the lightning shield proves effective, it will be counted another major advance. Ice Anchor for Dirigibles LAR ice caps would anchor dirigibles in a novel scheme suggested by a German engineer, O. Krell, and inspired by plans tentatively an- nounced for a_ polar flight, in the near future, by the German airship Graf Zeppelin. An electrically heated plate-shaped anchor would be used. Cruising over the ice fields, the dirigible would drop its anchor and hover while the hot plate sank into the melting ice. Then the electric current recently opened at New York University. POPULAR SCIENCE MONTHLY Future women pilots receiving first instruction in new ground school for women would be shut off, and the ice would freeze and hold the dirigible. Men and material could then descend via the anchor rope. When the dirigible was ready to leave, the electric current could be turned on once more and the anchor would pull loose from the melted ice. First Aerial Billboard HAT is said to be the first aerial advertising billboard in the world has just been erected near Detroit, Mich. Its tilted sign, visible both to highway travelers and to passengers who fly over- head from the local airport, advertises the merits of a brand of motor gasoline and oils. Sky riders say that its message is clearly readable from a plane flying at a height of 700 feet. A new scheme of “air-marking” to direct pilots is suggested by Harry H. Blee, chief of the airports division of the United States Department of Commerce. Highways afford the best place for aerial signposts, he says, since a pilot may then follow a road as a guide when flying over unfamiliar territory. Chrome-yellow or white letters ten to thirty feet high, painted on the highway, would tell him its official route number. Air Taxi—20 Cents a Mile IAXI service by airplane to any part of the United States.at a pro- posed rate of twenty cents a mile has just To commemorate the twentieth anniversary of the first airplane crossing of the English Channel, the plane in which Louis Bleriot made the flight recently was placed in the Science Museum, London. Here mechanics are assembling the plane. S. J. Donohue (center) is the instructor. DECEMBER, 1929 been announced by a New York City concern, which planned to start operation within a few weeks. There are no time-tables, nor fixed rates for a trip. The new line, of which a New York taxicab firm is said to be a principal owner, simply charges a regular mileage rate like that of auto taxicabs in cities. Auto cabs and motor boats will be codrdinated with the new service, it is said, in order to pick up the passenger at his doorstep and deliver him exactly where he wants to go. A similar service at a shilling a mile is announced by a British firm that plans to carry ‘‘fares” over England in planes just big enough for one passenger and his baggage. Mail Pick-up in Service LLOWING recent demonstrations of a device that enables pilots to pick up and drop air mail without stopping, the first of these devices has been placed in actual service on a Cleveland-Pitts- burgh air mail line. It is the invention of Dr. L. S. Adams, of Spokane, Wash. A speeding plane approaches the mail sta- tion swinging a weighted cable from its under side. A V-shaped trap on the ground directs the cable into a slot, where it hooks to a bag of mail and is then drawn up by the plane. In the same way a bag of mail attached to the cable is dropped off. Several practice flights preceded the inauguration of the regular service, which is expected to cut time from the mail schedules. Making Big Planes Safer DEVICE to disconnect the propeller of an airplane from its shaft so that it may revolve freely is a simple but in- genious invention recently given to his government by Sensaud de Lavaud, French aeronautical engineer. The result is said to be an increase in safety. Some aeronautical engineers have claimed that a_ two- motored plane is little safer than a ship with a single motor, since if one engine fails the other may have difficulty in pulling a loaded machine. De Lavaud’s invention eliminates the wind drag of the stationary pro- peller attached to a stall- ed motor. By allowing it to revolve freely, the wind resistance is ma- terially cut down and the work of the remain- ing engine lightened cor- respondingly. The me- chanical principle of the device is not unlike the “free-wheel” arrange- ment that allows a bi- cycle to coast without turning the pedals.

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DecEeMBER, 1929 POPULAR SCIENCE MONTHLY A Navy biplane hanging by a trapeze from the great dirigible Los Angeles during a recent demonstration of the t airship’s ability to pick up and dis- patch planes in flight (P.S.M., Nov..’29, p. 42). A Naval officer was transferred to the plane, which then landed him. Fitted with pontoon and landing wheels, this new Navy amphib-. ian plane, with 425-horsepower motor, can light on land, water, or the deck of an airplane carrier. The landing wheels, operated from the cockpit, may be raised or lowered, or may be tucked away in the pontoon when not in use. Above: Inspecting the new craft at the Naval Air Station, San Diego, Calif. Upper view shows the amphibian taxiing on water with wheels in flying position. Mail dropped by parachute from the air mail plane Shuttle during the re- cent attempt of Capt. Ira Eaker to pilot the plane to a new transcon- tinental refueling endurance record. At the left is a novel parachute basket invented by Captain Cragomir of Rumania. The basket is incorporated in the hull of a plane, where it serves as a seat. It is released automatically. The unusual new “tandem”? plane invented by George Fernic, of Staten Island, - N. Y. It is distinguished by two short wings at the nose and two large ones behind. In a recent test at Roosevelt Field, N. Y., it flew successfully for twenty-two minutes. Anthony Fokker’s newest creation, a giant thirty-two-passenger monoplane, photographed during its first public test flight at Fokker Field, N. J. Largest land plane in the world, it will be used for transcontinental passenger service. Four 425-horsepower motors drive it at a cruising speed of 120 miles an hour. 43, Aircraft and Flying Feats Out of the Ordinary TRAE oe | } | | |

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POPULAR SCIENCE MONTHLY DECEMBER, 1929 The Moon Is Made of Cinders Ingenious Measurements of Its Light and Heat Reveal the Old Man’s Pocked Face Powdered with Volcanic Dust NSTEAD of the silvery moon that poets praise it would be truer to talk about a cindery one. Cinders, the latest scientific re- searches indicate, are what the moon’s surface is made of; a special kind of cinders like those thrown out of earthly volcanoes and called pumice or volcanic ash. If there were any air on the moon to get up a wind, a moderate tempest might blow away the Man in the Moon overnight, for that imagi- nary portrait is “painted,” it is prob- able, in vast hundred-mile brush strokes of soft, loose pumice and still looser dust. The chief evidence for this comes from the moon thermometer perfected a few months ago at the Mount Wilson astronomical observatory of the Car- negie Institution, near Pasadena, Cali- fornia. This instrument is a delicate device for measuring heat rays, at- tached to one of the great Mount Wil- son telescopes. Similar instruments (thermocouples), based on the prop- erty of certain pairs of metals to pro- duce electricity when the joint between them is heated, were used several years ago by Dr. W. W. Coblentz, of the United States Bureau of Standards, and by other scientific men, to meas- ure the temperature of the planet Mars. For many months Dr. S. B. Nicholson and Dr. Edison Pettit of Mount Wilson have been using the thermometer on the moon. When the sun shines on it, the moon’s surface gets very hot. After sun- set on the moon the surface begins to cool. That is how the fact that it consists of some porous material like pumice has been discovered. | f tahoe kinds of rock take up heat or lose it at very different rates. A piece of polished marble, for example, feels cold if touched to the skin because marble absorbs heat rapid- ly, takes this heat from the skin and cools it. A block of pumice feels much less cool because it absorbs heat less rapidly. By delicate meas- urements with the moon thermometer, the Mount Wilson scientists were able to calculate how fast the moon’s surface warms up when the sun first strikes it and how fast it cools off when the sun’s rays leave for the night. With these measurements as a basis, Dr. Paul S. Epstein, a phys- icist of the California In- stitute of Technology, con- By THOMAS ELWAY A remarkable photograph of the half-moon taken with the 100-inch reflector of Mount Wilson Ob. servatory. Soclear are the craters and the darker, flat looking areas called “‘seas,’”’ that they can be mapped quite definitely, as on the opposite page. ducted experiments with various kinds of earth rock in his laboratcry. Heating them and cooling them, he compared the rates which they displayed with the heat- ing and cooling of the moon. Granite, black lava, quartz sand or sandstone; all were very different from the moon rate. Pumice, blown out by earthly volcanoes, was almost exactly the same. Thus he found that if the surface of the moon is not actually made of this pumice, it evi- dently consists of something which heats and cools in precisely the same way. This conclusion of a pumice moon is strengthened by facts learned, from a dif- A giant telescope to be erected in California will bring the moon’s surface within an apparent distance of twenty miles of the earth. The artist portrays here how its pocked, cindery face might appear if it actually came that close to the earth. ferent method, by Dr. F. E. Wright, optical expert of the Geophysical Lab- oratory of the Carnegie Institution, in Washington, D. C. Dr. Wright made use of the moon’s light which consists, of course, of reflected sunlight. The reflected moon rays are not quite the same in character as the original sun rays. Colors have altered slightly. The percentage of the special kind of light called polarized light is increased. Pre- sumably still other changes occur. Measuring these modifications of sun- light into moonlight, Dr. Wright and his associates compared the similar changes in sunlight produced by its re- flection from small laboratory samples of various kinds of rocks. As in the California experiments, the one kind of rock which seemed most like the moon in light reflection as well as in heating and cooling was the same volcanic pumice. The conclusion is that the moon’s face is sprinkled with a face powder of volcanic dust. WO earlier opinions of astronomers are confirmed by these new facts. One is the absence of a moon atmos- phere; for winds or rainstorms on the moon would change this loose surface dust continually, giving the moon a new face every week. The other is the idea that the mountains and great plains and crater like circles visible when the moon is examined with a telescope are really volcanic, just as they seem to be. The conclusion that the moon is airless has had recent confirmation, too, from Dr. W. H. Wright of Lick Observatory, in California. For several years he has been photographing planets and other astro- nomical bodies by light of different colors. His photographs of Mars by violet light, for example, are distinctly larger than photographs of the same planet made at the same time and through the same tele- scope but with red light. The explanation is that vi- olet light photographs the atmosphere of Mars as well as the planet’s solid surface. The red light photographs the surface only; which ap- pears, of course, slightly smaller than the planet and its atmosphere taken to- gether. Recently Dr. Wright ap- plied this method to the moon. No difference of size was detected. Photographed by red light or violet light, the moon looks just the same. The evidence seems conclusive that the moon

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DeceMBER, 1929 POPULAR SCIENCE MONTHLY rs TheopP hile prolemy Compare this map of the moon’s face with the photograph on the opposite page. more than 50 miles in diameter. has either no atmosphere at all or an atmosphere which is nearer to a perfect vacuum than the inside of the most com- pletely evacuated radio tube or elec- tric lamp. The volcanic theory of the moon’s features, now supported by definite evidence, has gradually been gaining ground among astronomers. The moon was formed, astronomers and geolo- gists now agree, out of a large fragment of the earth’s crust, pulled loose by ex- treme tidal action in the early days of the earth’s billions of years of history. Whether these earth fragments were hot when detached, the violence of such a cataclysm would be reasonably sure to heat them, so that the original moon must have been hot internally, if not outside. Dr. Harold Jeffreys, distinguished British authority on earth history, computes that the moon probably has in its interior consider- able heat-producing radium. A hot moon naturally would be volcanic, just as some remnants of primeval or radi- um-created heat still blow off occasion- ally through the earth’s volcanoes. Other theories proposed to explain the vast, volcano-shaped ring moun- tains of the moon’s surface are less The great ring-mountain Copernicus is Crablike creatures such as those in the smaller pictures may possibly live on the moon. plausible. One ascribes the ring moun- tains to the fall of gigantic meteorites in past ages, raising ridges of rock around the edges of the holes. Recently a Russian cano (A) would far outshoot One on the earth (B). Because of weaker gravity, an eusties moon vol- exploring party located a similar crater in Siberia, where a gigantic meteorite once hit the earth. This crater is far smaller, however, than most of those on the moon, and there are other reasons for deeming the meteor theory insufficient. N ENGLAND, the distinguished amateur astronomer, H. G. Tomkins, is sponsor for the idea that the moon mountains may be the remains of gi- gantic rock bubbles, lifted ages ago by accumulations of gas underneath, as internal gas lifts the domelike shapes of dough when the cook makes ‘‘pop- overs.” In time, he believes, the domed roofs of rock broke and fell in, leaving only the circular walls. The theory is an ingenious one, but critics point out that it is difficult to imagine such rock domes fifty or sixty miles across and still able to stand up by mere pressure of a vast gas bubble underneath. The enormous size of the moon cra- ters constitutes, indeed, the chief diffi- culty in explaining them. The lunar ring-mountain which terrestrial as- tronomers call Copernicus is more than fifty miles in diameter and with walls nearly four miles (Continued on page 143) shaman Be dial ae a An ik a - : ere Po

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46 POPULAR SCIENCE MONTHLY DECEMBER, 1929 “How I Fly My Plane” After 4,000 Hours in the Air, Lindbergh’s Former Partner Tells How He Solves the Problems Every Flyer Must Face By RANDY ENSLOW I was testing ships for the Robertson Aircraft Corporation at Lambert Field, in St. Louis. The mechanic gave his ““O.K.” HE queerest flying accident I ever had happened in Ohio. I was barnstorming in an old Standard _ biplane—a ship that was braced with enough wire to bale ten tons of hay. I could test it by letting a pigeon loose between the wings. If the bird found its way out, I knew a wire was gone somewhere! While flying cross-country be- tween two towns, I lost my way. I set the ship down in a field about the size of a hand- kerchief to get my bearings. I had to take off over a clump of trees. But in barnstorming, a pilot gets used to landing on a postal card and taking off from a stamp, so I wasn’t worried. But just before I tipped the trees, a flock of crows that had settled there was scared up by the roar of the plane’s motor. The air became black. A dozen struck the pro- peller. It went to pieces, exploding like a firecracker. A black blizzard of crow feathers blinded me. The motor choked dead. I shoved ahead on the stick and down we came in a pasture beyond the trees. In landing, we almost milked a cow and sat down straddling a barbed wire fence. But after I dug pieces of crow out of the motor’s air intake and put on a new “prop,” the ship was ready to go. It is when something unexpected like that pops up that a flyer discovers whether he is running a ship or it is run- ning him. And the only way to get by with an airplane is to run 7f, all the time. Thirteen years in the air has taught me that, if nothing else. ODAY, when I dropped down at Curtiss Field, Long Island, after ferrying a new Robin in from Schenec- tady, I totaled up my log book and found I have been in the air a little over 4,000 hours. Less than half a dozen people in the world have that much flying time. I began flying at fifteen. I have piloted every type of ship made in America. I have seen every state in the Union from the air, except West Virginia. And I am going down there next month. But the record [ am proudest of is that I have trained 500 students and not one has hurt himself or anyone else as far as I can check, and I’ve kept close watch. One of the first lessons a pilot has to learn is to keep track of the condition of his ship. Taking off in a crippled plane is about as safe and sane as going over on a new biplane job, and I jumped in without looking her over. Five hundred feet up, the whole balancing aileron on one wing sailed off into space! The mechanic had forgotten to put in any of the hinge bolts. The wing, without any balancing sur- face, began to tip—and how! I pushed the nose down ina spiral, then climbed out of my seat, perching on the fuselage back of the cockpit with my hands braced against the struts in front of me. If the motor poked By studying the different colors of fields below, Enslow tells which offers the best landing spot. In circle: By looking into the sky he can tell the wind direction. Niagara Falls in a leaky rowboat. Even expert mechanics slip. Once one hooked up the elevator flippers on “Merry” Merrill’s plane wrong. When the ship was supposed to climb it dove, and vice versa. Merrill was racing another pilot off the ground. The result was one of the sweetest somersaults you ever saw. Soa pilot should go over his plane himself before leaving the ground. We all get careless about that. But when we do, we pay sooner or later. My own lesson came early. It was the year after I barnstormed with Lindbergh. back through the cockpit, it wouldn’t find me! We crashed on one wing and the nose. The ship was a wash-out, but I was only shaken up. The part of a plane that needs the most attention is, of course, the motor. It pays to treat a motor right. It would take a human heart more than a month to beat as many times as a nine-cylinder engine explodes in a single ten-hour flight. Lindbergh’s Wright Whirlwind exploded twelve million times, without a rest, on his flight to Paris. I always warm up my motor gradually .

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DecEMBER, 1929 before a take-off. The first minute, I let it idle along at 600 revolutions. Then I speed it up to 1,000 and keep it there until the motor thermometer shows an oil temperature of ninety degrees F. The instrument on the plane that indicates how many revolutions the propeller is making is the tachometer. When a pro- peller breaks in the air, the tachometer hand shoots over to 3,000 as the motor races. The vibration nearly shakes the fillings out of your teeth. But it doesn’t last long. The motor sucks gas faster than the carburetor can supply it and stops. If half a propeller breaks off, the pull of the other half often tears out the engine before you can jerk back the throttle. T CRUISING speed in the air, the tachometer shows from 1,450 to 1,500 ‘‘revs” a minute. By watching the thermometer, the oil pressure gage, and the tachometer, I keep track of how my motor is functioning. Increased vibration or a change in the sound of a motor will often warn that it is getting ‘‘rough” and may give trouble. Some pilots start with the motor oil tem- perature at forty degrees. But they take a chance. A cold motor may quit over the edge of a flying field—usually one of the worst places in the world for it to quit. In such a case, it is almost always best to land straight ahead, even if there is a stone wall in the,road. Turning back at low altitude with a dead motor usually means a bad crash. One of the most ticklish landings I re- member was made just outside a flying field in Michigan. It was the dead of winter. I was taking off with a passenger. The motor quit over a maze of tracks, highways, and telephone wires. The only field near enough to be of use was a little potato patch with the frozen ridges run- ning at right angles to the wind. The ship was so cold she cracked and popped all over when I set her down. But she POPULAR SCIENCE MONTHLY stuck to the runways and came to a safe stop in spite of the side wind. In speeding up the motor for the take off run, I advance the throttle gradually, taking about four seconds to push it clear ahead. This lever, usually called the ‘‘gun,” is on the left side of the cockpit. It is held with the left hand while the right grasps the upright control stick which keeps the ship on an even keel sidewise and points the nose up or down. The rudder is governed by a foot bar or pedals on the floor. Newspaper stories are full of ‘‘he gave ’er the gun” and ‘‘he cut the gun.” They give the impression that pilots jerk their motors on and off, racing them one minute and idling them the next. In emergencies, we do have to slap on the throttle. But when- Adjusting the magnetic compass which guides the pilot through fog. The compass is easily com- pensated, or set at true north, by screws which vary the distance between magnets and needle. It is mounted on the airplane’s fore-and-aft center line and away from iron and steel parts. Pointing out the bank- and-turn indicator. Enslow calls it “the most important instru- ment on the board.’’ 47 Enslow explains to the flying field mascot how rain entering the openings in the air speed indicator tube may make the dial readings go “haywire.” ever possible I save the engine by altering its speed gradually. As a ship runs down the field for the take-off, the hand on the air-speed indi- cator advances. On the machines I now fly, it usually touches sixty before we climb into the air. Two little tubes, pointing ahead of the wing, regulate this instrument. One tube is open at the end, letting the air rush in. The other is closed and has tiny open- ings around it a little way back from the end. The rush of air past these open- ings Causes a vacuum inside. The lower pressure of the vacuum and the push of the wind balance each other so the true air speed is shown on the dial. If rain gets into the little openings, the indicator hand seems to go crazy. Once I was flying blind through fog and drizzle between Buffalo and New York. When I looked at the air-speed indicator, my eyes popped. It showed 300 miles an hour. Two hundred would tear the wings off the machine I was flying. I pulled back the stick gently. The ship began to climb. The hand advanced to 350. Then I knew the instrument had gone ‘‘haywire.”’ HE air-speed indicator shows only how fast a plane is going through the air. It does not indicate ground speed. The plane may be going sixty miles an hour through the air, but if it is bucking a forty-mile-an-hour gale, its ground speed is only twenty miles an hour. If it is flying with that gale its ground speed is a hundred miles an hour. So, on

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AS cross-country flights, I time myself over the first third of the journey to get an estimate of my ground speed to see if the fuel will hold out. HE fastest I have ever flown with the wind was in Florida, when I was chased by the tail end of last year’s hurricane. Below me, the eighty-mile-an-hour gale was tearing the roofs off houses as I shot past at 140 miles an hour. Yet, all the time, the indicator showed only sixty miles an hour—my speed through the air. If a vote were taken among pilots, I imagine the instrument that would be selected as the most valuable would be the bank-and-turn indicator. It shows whether the wings are level when there is no horizon on which to ‘‘line them up.” If one wing gets low in a fog, a ship may start side-slipping without the pilot real- izing it. The climb indicator shows whether the ship is ascending, descending, or flying on a level. As a machine climbs into the air, its height is recorded on the altimeter. This instrument is governed by a sensitive metal drum that expands and contracts with variations of atmospheric pressure. Before each flight, its hand must be set. If a ship sits all day or overnight, normal changes in the air pressure may cause the altimeter to indicate it is hundreds of feet in the air or an equally impossible dis- tance underground. A rise or fall of a hundred feet is scarcely noticeable on the aver- age altimeter. Such instruments are not ac- curate enough for blind flying at low altitudes. Below eight or nine hundred feet is the danger zone. However, I once dove and looped a ship at 300 feet. Only once have I pulled a crazier stunt in the air. That was when ‘‘Nick” Almgrim and I were barnstorm- ing in Ohio. We had tagged along an old ‘‘Jenny” biplane that was born before the war. At last we got tired of having the fly- ing tumbleweed around. So, at a Fourth of July cele- bration at a little town near Columbus, we gave everybody—including myself— the thrill of their lives. We packed the old bus with excelsior dipped in kerosene. I took it up a couple of thousand feet, touched a match to it, and crawled out with a parachute. Floating down, I had a grandstand seat to watch the flying bonfire. HAVE heard pilots tell of battling up 2,000 or 2,500 feet through fog with- out using their instruments. I’m from St. Louis. And that’s in Missouri. They will have to show me. When my senses tell me one thing and the little dials on the instrument board tell me another, usually the dials are right. I’ve never doubted that after one experience I had flying in California. The ship nosed into a big cloud at about out one side of the cockpit. flight. The instrument should be set at zero each day, Enslow says, otherwise changes in pressure will make its readings inaccurate. POPULAR SCIENCE MONTHLY 7,000 feet. The fog was so thick I could hardly see the propeller. The wings dis- appeared. The tail seemed to drop off. Sitting in the cockpit was like riding in a little bathtub a mile above the earth. When I dropped out of the cloud, I looked over the side of the ship to get my bear- ings from the ground below. What I saw was blue sky and clouds. I had been flying upside-down without knowing it! If I had remained long in that position, blood rushing to my head would have warned me. But bodily sensations are usually too slow to trust in a modern ae PP . J \ g : i) Enslow shows how he has steered a small plane by sticking his hand Above: Setting the altimeter before a ship. Things happen quick in the air. Next to the instruments, probably the pilot’s safest guide to the position of his ship is the seat of his pants. When the nose is up and he is climbing, he feels ‘‘*heavy” in the seat. When it points down, he feels ‘‘light.’”” When one wing drops, he feels heavier on the ‘‘uphill’’ side. When the ship*skids on a turn, he feels himself tending to slide outward. After several hundred hours in the air, a flyer learns to respect these reports from the place where his trousers get shiny. Unless he develops ‘‘seat sense,” a pilot won't get far. Another thing learned from experience is to judge the steepness of glides by the humming of the ship’s bracing wires. The steeper the glide, the higher the pitch of the sound. In a “graveyard glide,’ when the descent is so flat the ship is almost stalling, the humming is \ DECEMBER, 1929 low and practically dies out altogether. After a thousand hours in the air, a pilot observes things like that uncon- sciously. He develops abilities he didn’t have before. I find that I can lean back in a cockpit, look up into a clear sky, and tell which way the wind is blowing. I can’t explain it, but I ‘‘feel it in my bones.” On cross-country trips, a knowl- edge of wind direction is necessary be- cause a flyer must face into the wind ina forced landing. And on a cross-country flight there are no ‘‘socks,” or wind cones, below as there are at an airfield. Before a pilot develops the ability to “sense” the direction of the wind, there are signs he can look for on the ground. He can note which way smoke is car- ried from factory chim- neys and locomotives, or can see how dust drifts away from country roads when an auto passes. Windmills point into the wind and clothes on the line indicate its direction. Ripples on water, grain, or grass show it also. If none of these can be ob- served, he can put the ship into a circle and keep it going like a merry- go-round, noting the di- rection in which it is carried by the action of the wind. 73 OT long ago, I tested a little plane about the size of a mos- quito, for a man down in North Carolina. The tiny ship got off the ground in the length of two telephone poles. It was so light that, when I stuck my hand out one side of the cockpit, the plane turned, just as a boat turns when an oar is held in the water on one side. By holding out a hand first on one side and then on the other, I cut figure eights without touching the rudder bar. Such ships are too light. They are too tricky. Gusts upset them too easily. Only a pilot of long experience can guess what they are likely to do next. Re- member that the next time you read of fleets of flivver planes being built weigh- ing only a few hundred pounds apiece, for everyone to fly! I once ran into a whirl- wind over Long Island with a light ship. It was flipped upside-down before I could catch my breath. To be safe and stable, I’ve found a ship should weigh at least 1,600 pounds. The largest plane I have ever flown had a wing spread of 110 feet and weighed several tons. Big, heavy ships like the tri-motored Fords have a wheel at the top of the control stick. You turn the wheel to maintain sidewise balance and move the stick ahead and back to go up or down. It takes more force to move the controls on such planes and an ordi- nary stick might break off in heavy weather. N SHORT cross-country trips, I usually follow a highway or railroad. On long journeys or in blind flying in fog, I use a magnetic compass. The earth in- ductor compass, such as Lindbergh used on his flight across the Atlantic, costs too much forany (Continued on page 146)

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DecemBer, 1929 HE most famous crystal in the world, the Kohinor dia- mond, ancient Indian gem of evil and mur- derous history now safe- ly caged among the crown jewels of England, soon may lose its alluring supremacy. A few weeks ago before the meeting of the American Chemi- cal Society at Minne- apolis, Professor J. Wil- lard Hershey, of Mc- Pherson College, showed a tiny seed of a gem greater still. His micro- scope crystal, the Pro- fessor said, is an arti- ficial diamond. Soon he hopes to make larger ones; not to ruin the diamond market, but to aid a new and necessary science. Even the famous Ko- hinor is not the largest diamond in the world. That honor belongs to the Cullinan stone, the cut fragments of which are also among the treasures of the Brit- ish crown: Professor Hershey’s diamond is perhaps the smallest in the world which anybody deems worth saving. Yet its value for the future may be enormous, for it promises better understanding of the remarkable things called crystals. Every r diamond is a crystal, and every crystal is like a tiny skyscraper built of atoms, piled up in regular patterns like the frame- work of the building. O ONE can get far away from crystals. Every sand grain on the seashore is reasonably sure to be a tiny crystal. Each snowflake is a crystal’s beautiful skele- ton. The most useful crystals to man are per- haps those of table salt, = L without which no warm- blooded animal can maintain the necessary saltiness of its blood. If by some magic every crystal in the world suddenly van- ished, all buildings of brick, stone, or concrete would disappear; steel bridges would collapse into dust; jewelry would be robbed of its gems Rough diamonds (above) from the mine are cut and sliced by the machine at the right to bring out the crystals’ hidden brilliance. POPULAR SCIENCE MONTHLY Diamonds and Salt— Tiny Skyscrapers Built of Atoms By E. E. FREE and the gold and platinum left behind would grow soft and spongy like bits of eggshell; nobody would have sugar for his coffee. For all these things are crystal forms of one kind or another. Yet many things that people call crys- How the atomsof carbon are arranged in a diamond. 49 Soviet officials examining and appraising one of the greatest crystal collections in the world, the diamonds and other gems of Rus- sian Crown Jewels taken from the former Czar. tals would not vanish; ‘‘crystal glass,” for ex- ample, for glass is not a crystal at all. Even the so-called crystal globes of psychic gazers are sel- dom real crystals. EFINITE _ knowl- edge of what crystals are has become possible only since the modern development of knowledge about atoms. In ancient days any bright, transparent stone was called a crystal. Professor W. J. Perry, the distinguished Eng- lish anthropologist, says that search for these gleaming objects in streams and along the seashore probably was one of the first civilized activities of mankind; that it was the basis of the first world commerce and the spur to the first human migrations. Nowadays the lure of crystals persists. Men and women sell their lives for bright jewels; rich collectors amass stores of beautiful crystalline minerals; scientific men delve into the insides of crystals, not seeking beauty for the eye but new facts about the universe. The new atomicscience of crystals is in many ways the reverse of the equally | new science of colloid chemistry (P. S. M. Oct. ’29, p. 42). In colloids, like egg white or glue, the atoms are arranged more or less at random, like a vast crowd of people strolling about in a field. In crystals, like diamonds or granulated sugar, the in- ternal atoms are fixed in rigid patterns, like soldiers in perfect order at a parade. That is why crystals are likely to have bright, flat surfaces which brilliantly re- flect the light, as do the facets of a dia- mond. The last rows of atoms on the outside of the crystal all stand in the same plane, like the men of a parading regi- ment or the flat front of a building. From such surfaces light waves shine back easily and perfectly. Some noncrystalline ma- terials can be shiny, too, as polished glass is, but such things are usually without brilliance. If there were a micro- scope powerful enough to look inside a crystal, like Professor Hershey’s tiny diamond, it would be easy Sip yen Sta see, Pe Res TS ee RA SF DERG CEE ERT: F

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50 to see how important is this regularity of arrangement of the atoms. There actually exists, indeed, a kind of micro- scope able to make these crystal in- teriors evident if not literally visible. This instrument is the X-ray. Eighteen years ago a Swiss physicist, Max Laue, sent narrow beams of X- rays through fragments of crystal, like a thin slice of diamond. He discovered that the X-rays were bent out of their paths in peculiar ways, now known to be related to the arrangements of the atoms inside the crystal. These observations were extended by Professor (now Sir William) Bragg in England, by Dr. Wheeler P. Davey in the United States, and by others. The result is that X-ray methods now make it possible to see, within reasonably wide limits, just how the atoms are arranged. ‘ HE first rule is regularity. The pat- tern of atoms in a crystal continually repeats itself. In a diamond all of the atoms are of the same kind, like the sky- scraper’s iron beams, for diamonds are the chemical element carbon in a pure state. A convenient model of the atom pat- tern of a diamond is an ordinary cubical die, like those used in gambling games, but with its faces all marked alike with five black spots. This would represent one unit cube of the diamond’s atomic pattern. Each cor- ner would be occupied by one carbon atom corresponding to one black spot on the die’s face. At the center of each cube face would be another atom; this one mak- ing with the four corner atoms the five- point figure of each face. Inside the unit cube would be four other carbon atoms, arranged to form the figure which geome- ters call a tetrahedron. Throughout the whole structure of a diamond this unit cube is repeated billions of times. It is the diamond’s fundamental atomic pattern, called the “unit cube.” Lacking this definite structure, no assemblage of carbon atoms can be a diamond. The mineral called graphite, used to make lead pencils, is also com- posed of carbon. Often it is as pure as a diamond or purer. Yet it never re- sembles a diamond. Instead of being the hardest substance known, graphite is among the softest; instead of being transparent and incomparably brilli- ant, graphite is dull, black, and opaque. Yet the only difference between the two is in the arrangement of the atoms. HERE is still dispute about the exact unit cube in which the car- bon atoms of graphite are arranged to differ from the five-point arrangement ‘ of the diamond. This has been the problem of the would-be makers of artificial diamends, and one which Professor Hershey now believes he has solved. It is easy enough to prepare pure car- bon and to make its atoms stick to- gether. A little coke or charcoal, for POPULAR SCIENCE MONTHLY The world’s most beautiful crystals are snowflakes. The two above are from photo- graphs by W. A. Bent- ley, world-famous snow- - flake expert. At right is a model of atom , positions in an iron : é crystal; at the left, in r 9 i a crystal of copper. dissolved carbon freezes out, as sugar will freeze out of syrup when it gets too cold. But the carbon does not freeze out of molten iron as diamonds; it appears as graphite. The noteworthy thing about Professor Hershey’s reported experiments is that he seems to have succeeded, by proper control of the surrounding condi- tions, in inducing the carbon atoms to ar- range themselvesinthe diamond pattern. N SOUTH AFRICA, where most of the world’s diamonds are found, these gems often occur in a curious, partly dis- integrated rock called “blue ground.” Geologists believe that millions of years ago this blue ground was in process of hardening deep in the earth; probably cooling for millions of years from a previ- ous molten condition under a pressure of millions of tons to the square inch. Some unusual circumstance caused carbon atoms dissolved in the molten rock to gather together, it is believed, into the diamond pattern instead of the graphite pattern. Whether that circumstance was the extreme pressure or the very slow cooling or something else, no geologist nor crystallographer knows. If Professor Hershey really has turned the trick in his DECEMBER, 1929 laboratory, it may now be possible to find out precisely what makes carbon atoms act in this way. If similarity to other crystals means anything, one necessity for the mak- ing of large diamond crystals probably will turn out to be extremely slow growth. One of the easiest substances to prepare in crystal form is ordinary sugar. The large, square-looking crys- tals of rock candy are the result. To make rock candy, the small sugar crystals are allowed to grow larger. If the candy is made very slowly, by allowing a sugar syrup to deposit its load of sugar molecules only a few each day and at a constant rate year by year, single sugar crystals can be grown as large as hen’s eggs or as footballs. This is the secret that every scientist wishes he knew about less complacent crystals, like diamonds. That the secret of making substances form larger crystals than usual can be learned is proved by recent successes in the study of metals. In examining the properties of metals important in electri- cal engineering, like tungsten for the fila- ments of electric lamps, it became de- sirable to examine metal crystals larger than the ones observed under a micro- scope. So new methods were devised to “grow” large metal crystals, like the large sugar crystals of rock candy. Rods of copper; iron, or other metals were put in electric furnaces and kept at exactly the right temperatures for weeks or months. | Slowly the atoms of copper, for example, rearranged themselves completely into the repeated unit structure of a copper crystal. Single crystals of these metals inches long have been produced thus and subjected to electrical and mechanical study. HE unit cubes which represent the atomic patterns in copper, iron, and other metals are not exactly the same, of course, as the five-point dice which form those of a diamond crystal. Cop- per crystals have, however, an arrange- ment not very different. The five- point dice faces are still there but there are no extra atoms _ inside. Crystals of pure iron appear to have a still simpler unit cube; like a die with four points on each of its faces instead of the diamond’s five. There is an extra iron atom, too, at the cube’s center. Other elements and compounds show still other atom patterns. Hun- dreds of different patterns are now reasonably well known. Nearly all have been: worked out by the X-ray, the chief tool of crystal explorers. Out of such unit patterns and their com- binations, all the myriads of crystal forms of minerals and chemical com- pounds ‘are believed to be built up, as an artist might construct millions of separate designs out of simpler units like cubes or circles or triangles. One of the best known of all crystals, and perhaps the most useful scien- tifically as a yardstick to measure Crystals make radio broadcasters toe the line. Here H. W. Arlin of Westinghouse station KDKA is holding a tiny plate of quartz that keeps the wave length true. sizes throughout the whole crystalline example, may be dissolved in molten world, is that (Continued on page 140) iron. When the iron cools some of this

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DerceMBER, 1°-) POPULAR SCIENCE MONTHLY 51 A Box of Sounds for the Movies HE ingenious mechanism by which the modern electric pipe organ pro- Re. duces an almost endless variety of - sound effects for the movies, ranging from 0 Piss the thunder of a storm at sea to the : music of a symphony orchestra or a iru human voice, is pictured here. An organ

of this type contains nearly a hundred miles of electric wiring and an intricate system of switches, through which the operator at the console, merely by touch- BA LL ; ing stops or pedals, can produce the sound th or combination of sounds desired. } Wind supplied by a motor-driven i LE | blower sounds the pipes and actuates i |

other instruments, such as drums, tam-

. OR VO bourine, xylophone, and bells through pint electric controls. The design of the vari- —- ge at, ous pipes to imitate different musical = : | a . instruments is a science in itself. Volume | , ne, ye i | D fe , Sie i Poei.s Sati (3 a 4 ‘ $e BO * eee : . Al Cs |e f ¥ : i ELAY iy a me : | 20 Hi S 4 ) ' ee ee eS o.. : 3 H alg Boe oa { me = ad 1a © | fp CONSOLE: i eo ‘ ee " . ff f ks ga ' y 65 eugy . AAG % + a ; ee & oe /\ ty ye i : | HL : | ‘ 4 > “ ‘ HANI we “> 0 <a | ~ can | » ms P BELLOWS aM : —? WIND : 3 ok CONDUCTORS O ao Mi ES a z ELECTRIC CONTROL THROUGHOUT po BUT MOTIVE POWER FOR ALL en & MOVEMENTS 15 WIND y sa wer do 008 48. 3 <_ ew ere wv eve g The view of the console (lower

TRUMPET Aw an idea of how an organist, by electric control, can produce an almost infinite variety of sound effects. Console and organist are elevated above the audience by an electric motor. Various types of pipes are shown at left. The drawings are by B. G. Scielstad. BASS VIOLIN CLARINET OPEN DIAPASONS,

BOURDON OR BASS, HUMAN VoIce left) with its arrangement of [ manuals, stops, and pedals, gives

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KARL VOOGHT . HERE isastory of a medieval prisoner who could see from his cell window nothing but a patch of sky. So he became, as the years dragged on, an expert in clouds and pro- nounced the weather forecasts for the neigh- borhood. The tale is scientifically plausible. Weather instruments like thermometers and wind measures, the stand-bys of modern weather forecasting, tell only of the bot- tom of the air ocean surrounding the earth. Clouds disclose, or may disclose, what is going on in this air ocean a mile or two above the ground. Among French weather experts much use is made of cloud shapes and cloud movements in weather forecasting. More use might be made of them everywhere were there satisfactory classifications of types of clouds. That is one reason why an international committee of weather experts is now at work on new cloud clas- sifications and on the preparation of a new International Cloud Atlas in which typ- ical clouds will be illustrated. Literally hundreds of different names have been proposed for types and sub- types of clouds. Amateur weather ob- servers, confronted by this complexity, commonly abandon cloud studies alto- gether. The difficulty seems to be that clouds, like most other natural Ellerman. T POPULAR SCIENCE MONTHLY ack of the Month’s News High cirrus clouds photographed from Mount Wilson, California, by Ferdinand hese clouds are composed of tiny ice crystals. prophet, cloud forms and cloud move- ments played a large role in weather lore. It is probably a loss to weather science that they have been displaced. If cloud classification can be simplified so that ‘everyone can understand it, perhaps the clouds will come back to their own as indicators of weather probabilities. Power by Radio Possible? HE dream of distributing electric power by radio is almost as persistent a will-o’-the-wisp as that of perpetual mo- tion. It has, perhaps, somewhat more chance of fulfillment, for no fatal obstacle of physical theory stands in its way, as the principle of the conservation of energy stands in the way of producing power for nothing. Yet the incidental difficulties of radio power transmission seem almost in- superable. Latest of speculators concerning radio Scientists are making new classifications of cloud formations and movements to aid weather forecasting. DECEMBER, 1929 power possibilities is Dr, Jacques Risler, a Pari- sian physicist already known for researches in the use of ultra-violet rays and other invisible radiations. In the use of radio waves of extremely high frequency and low losses in the atmosphere, Dr. Risler sees at least a possibility of useful power transmission. The difficulty with radio power, as was per- ceived more than two years ago by Dr. Phillips Tromas, the foremost American experimenter in this field, is not so much the loss of power suffered when radio waves pass through the atmosphere as it is the invincible tendency of these waves to spread outward and waste their energy, as ripples spread on the surface of a quiet pond. Were it possible to condense radio energy into a definite beam, as can be done with the light rays of a searchlight, greater possibilities would be apparent. To some extent, as Dr. Thomas proved, this beamlike condensation can be man- aged, but not sufficiently thus far to threaten the present systems of distribut- ing power through wires. With rare exceptions, energy has an incurable habit of spreading itself as thin as possible, like water spilled on the floor or like a handful of gas atoms let loose in a vacuum. Most of man’s accomplish- ments in handling energy, like those, for example, which are responsible for objects, refuse to fit perfectly into any series of artificial pigeonholes. Always there are intermediate cloud types for which the classification has no place. Three chief types include, how- ever, most of the main cloud forms. First are the cumulus clouds, Latin for “heap,” which pile up in moun- tainlike masses in summer skies. Second are the stratus clouds, Latin for “sheet” or “layer,” which cover the sky more or less completely at a fairly uniform level. Third, and most beautiful of all, are the cirrus clouds, named from the Latin word for “curl.” These cirrus clouds, usually much higher above the ground than other types, are not composed of water droplets but of DEFECTS NEEDING ATTENTION FOUND ON INI- TIAL EXAMINATION AMONG CHILDREN 5-7 YEARS OF AGE IN OLEAN AND IN RURAL SCHOOLS IN CATTARAUGUS COUNTY, 1926-1928 HEART NERVOUS SYSTEM LUNGS OF CHILDREN EXAMINED ° CENT PER GB ONE ROOM VILLAGE OLEAN electrical engineering, have con- sisted in some device to keep the energy in one place until it is used. The energy of steam is kept inside the boiler by the steel shell. The energy of electricity is kept inside the wires by a covering of insulating material. Dr. Risler’s difficulty is that there is nothing to keep radio energy inside the path assigned toit. Nervous Cities ITIES are dangerous weapons which mankind has by no means learned to control, some philosophers claim. They contend that the city man, for all his advan- tage in schools, social contacts, and in earning a living, will be less tiny crystals of ice. Before the daysof modern weather science, when each farmer or ship’s captain had to be his own weather This comparison of defects among children in one-room rural schools, in village schools, and in city schools of Olean, N. Y., shows that the city children suffer more from nervous disorders, but less from other defects. healthy, happy, and long-lived than his country cousin. Little actual evidence of these familiar conten- tions has ever been obtained, but |

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DecEMBER, 1929 Weighing one of the children examined in the health survey which revealed comparative defects in city and country children of Cattaraugus County, N. Y. one bit came to light recently in the work of the Milbank Memorial Fund of New York City. In Cattaraugus County of New York State, demonstrators financed by this Fund have conducted for some years health inquiries and surveys. Cattaraugus County includes ,the small city of Olean. The investigations show that children from the country districts of the County, as con- trasted with children in Olean, suffer sub- stantially greater per- centages of various bodily defects. Imper- fections of heart, lungs, skeleton, skin, teeth, and eyes were found to be much more preva- lent among the country children than in the city children, but pre- cisely the reverse is true for defects of the nervous system. Chil- dren in Olean disclosed more than four times as many such nerv- ous difficulties, on the average, as were found in children from the country. This finding indicates that city life, even in so small a city as Olean, puts upon the nervous system of the average child a greater strain than is encountered in the country. Many reasons might be ad- vanced for this: late hours, too much excitement, overcrowding, city noise, and others. Only by continued, accurate in- vestigation will the truth be disclosed. Meanwhile, physicians and psycholo- gists agree that the percentage of mental disease and mental deficiency in the United States is increasing, especially in cities. Is the modern city, perhaps, too nerve-racking an institution for man’s present mental and nervous. equipment? The Newest Arch Dam = prosperity of Los Angeles, Calif., depends not on tourists or on Holly- wood movie stars, but on hydraulic en- POPULAR SCIENCE MONTHLY gineering. Of all large American cities, Los Angeles has the smallest natural water supply. During most of the year the so-called Los Angeles River is a dry gully. Long ago the growing city exhausted all possible resources of wells drilled into the plain on which it stands. It has been necessary for the city engineers to go far into the desert and bring down the Owens River and to catch and conserve every gallon of available rain water in the city’s neighboring hills. Now, by means of the Boulder Canyon Dan, it is proposed to tap a portion of the great Colorado River lying to the east. Among many smaller engineering works closer to the city is the Dalton Dam, just completed near Glendora. It will provide irrigation water, flood protection, and emergency drinking supplies for some of the southern California territory. With a capacity a little short of 400,000,000 gallons, the Dalton Dam is not remarkable for size. The Roosevelt Dam in Arizona, for example, holds over a thousand times more water. The Elephant Butte Dam in New Mexico will hold two thousand times more. The engineering interest of the Dalton Dam is in its construction, for it employs the relatively new type of the multiple arch. Dams may be classified into three The new Dalton Dam near Glendora, Calif., which will pro- vide irrigation, flood protection, and emergency drinking water for sections of southern California. The upper view shows its multiple arch construction. Huge concrete abut- ments which reinforce the dam are shown in the lower photo. 53 types. First are those held down merely by weight, like the old-fashioned earth dams in which ordinary soil or broken rock is dumped across a valley to make an artificial hill. Most stone and concrete dams are constructed similarly, the struc- ture being merely a plug of solid material laid down across the valley and fitted closely against the underlying rocks. A more modern type is an anchored dam, in which the wall of concrete or stone is sunk into the rocks at the sides and bottom of the valley, so that the dam acts almost like a bolted door or like the gates of a canal lock. Still more modern is the arch dam, in which arched struc- tures of suitable shape are faced upstream against the water pressure, so that this pressure wedges the dam into the valley, like a properly-shaped stone hammered into a crack. The advantage of arch dams, whether single or multiple, is that less concrete needs to be used for equal stability and strength. Stars Too Hot to See R. LOUIS BERMAN, of Lick Ob- servatory, Mount Hamilton, Calif., has discovered some of the queerest stars in the universe—stars that are too hot to see. The hotter any object is, the more violet and ultra-violet light it emits in proportion to the green and red. For example, “white” or “blue-hot” iron is at a much higher temperature than metal just glowing a cherry red. It is possible to conceive of an object so hot that most of its radiated energy lies in the ultra-violet, in which case it may be impossible to see it or photograph it. Dr. Berman’s stars are of this variety, and his method of detecting their existence is ingenious indeed. HERE are certain objects in the sky known to astronomers as the “planetary nebulae.”’ These are spheres of luminous gas, such as hy- drogen, helium, and oxygen. Studies with the spectroscope show that the source of luminosity is a star at the center of each. That these stars are extremely hot is evidenced by the fact that they can be seen visually only in telescopes of highest power, whereas their near-ultra-violet light, al- though unperceivable to the eye, is so intense that the star is always conspicuous on a photographic plate. Just as a radio receiver is capable of absorbing ether waves vibrating too fast to be heard and transforming them into audible sound, the atoms that form the nebula are able to pick up the rapidly vibrat- ing ultra-violet energy radiated by the central star and re-emit it as light that can be seen or photographed. The hotter the star the more abundant is the invisible radia- tion, and, consequently, the brighter the nebula. In some of the planetary nebulae no central star has been seen, which, of course, raises the question of what makes them

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54 shine. Dr. Berman discovered that the atoms composing this variety of nebula are unusually disturbed, and has suggested that central stars actually exist therein but that by far the greatest pro- portion of radiation lies in the ex- treme ultra-violet. In other words, the stars are literally too hot to be seen. Dr. Berman’s study indicates that temperatures of 35,000 to 50,000 degrees centigrade for plan- etary nuclei are not uncommon and that still higher values are in- dicated for many. Compare these figures with the sun’s temperature —6,000 degrees. Apparently the planetary nuclei are the hottest objects yet observed on earth or in the heavens. Universal Yardsticks YSICISTS have dreamed for years of being able to measure everything in the universe, such as atoms, light, and the gravitation of the planets, in terms of a few universal con- stants, more fundamental than such arbi- trary units as feet or gallons. The speed of light in a vacuum is one of these funda- mentals, for all tests indicate that this speed is always and everywhere the same. Months ago Professor Raymond T. Birge, of the University of California, undertook a critical summary of all avail- able information concerning the exact values of these physical constants of Nature. The results have now been pub- lished by the American Physical Society, together with reprints of the constants themselves on sheets of cardboard, so that working physicists can tack them up for laboratory guides as business men use calendars. There are 103 units and ratios in Professor Birge’s list, but many of these, admittedly, are convenient figures for making calculations rather than fun- damental ones. Ten of Professor Birge’s figures are of first importance. Two are atomic weights as used by the chemist—the weight of the oxygen atom and that of the hydrogen atom. These provide a basis for atomic weights of other elements. Another fun- damental is the freezing point of water or, what is the same thing, the melting point of ice. This fixes the most important fun- damental of the scale for thermometers. NOTHER vitalconstant is the so-called mechanical equivalent of heat; that is, the precise amount of heat set free when a ° certain quantity of mechanical energy is used up, for example, in friction. Two electrical constants are included among the ten. One is the Faraday constant, which represents the amount of electricity carried by a definite number of atoms in an electrochemiciui reaction, such as elec- troplating. The second is the electric charge of one electron, as determined by the classic investigations of Professor R. A. Millikan. Still another fundamental is the volume of a perfect gas, since this lies at the root ofall calculations of atmospheric pressure, steam boiler behavior, refrig- erating machinery, and hundreds of other items of technical equipment. Among the three remaining constants on the list is that of the velocity of light, POPULAR SCIENCE MONTHLY Dr. Albert A. Michelson, distinguished physi- cist of the University of Chicago, with the new transmitting apparatus he is using in experiments to obtain a more exact measurement of the velocity of light. His measurements in previous experi- ments placed the figure at 186,284 miles a second. of which the most accurate measurement —186,284 miles a second—was obtained in experiments by Dr. Albert A. Michel- son, distinguished physicist of the Univer- sity of Chicago (P. S. M., Aug. ’29, p. 48). Dr. Michelson now is working with new apparatus to obtain a figure even more exact. Another is the constant of gravita- tion (about the inner meaning of which science knows virtually nothing). Most important of all, perhaps, is the mysteri- ous “Planck constant” which shows up in A busy day for the tattoo artist. Most of the designs, samples of which are seen on the wall, have historical, patriotic, or other symbolic meanings. Many have the flavor of the sea. DECEMBER, 1929 scores of physical phenomena, from the behavior of atoms to the heat radiated from a cooling body. No one knows what this ‘‘Planck constant” represents, butitis so commonly discovered when the analy- sis of physical facts is pushed as far as possible that physicists suspect it of having some very important meaning concerning the inmost structure of the universe. History in Tattoos HAT are regarded as im- portant fragments of ancient Egyptian history have been re- covered from living Egyptian skins. For. some years a distin- guished British anthropologist, Miss Winifred S. Blackman, has been studying existing races of man in Egypt and comparing these with their ancestors. Many modern Egyptians carry on their faces or bodies tattooed designs. One day it occurred to Miss Black- man to study what these designs are. To everyone’s surprise they turned out to be very ancient. Some have been identified as go- ing back more than 3,000 years, to the times of Joseph and Moses. Others have been traced to ancient Babylonia, to Persia in the days of Darius the Great, and to other ancient lands. Miss Blackman has made a collection of more than one hundred designs used by modern tattoo artists in Egypt. These designs will be preserved and studied as carefully as though they were actual docu- ments from ages long past. From such study, it is believed, clues to obscure facts of ancient history may emerge. The art of tattooing probably is, with one exception, the oldest in the world. The exception is the use of the paint pot and paint brush with which ancient peoples were accustomed to decorate their forms. In the beginning, all of these painted and tattooed designs probably were important symbols. They marked the positions of the decorated individuals in definite tribes, clans, or religious sects. The famous Moslem traveler, Ibn Bat- tuta, who visited Egypt in the fourteenth century, describes the practice governors of Egyptian cities had of stamping on the arms of visitors in indelible ink a mark indicating freedom to leave town, just as modern customs officers stick little print- ed seals to travelers’ baggage. Tattooing, it is probable, was often a symbol of the same type, though more permanent. Modern tattooing, if studied carefully, might disclose equally interesting facts. Most of the tattooed designs still in use have obvious historical, patriotic, or other symbolic meanings. Even when worked into the skins of peoples who are not sailors, these modern designs often carry the flavor of the sea. Sea serpents and sailing ships decorate the chest of many a man who has never seen the sea. A Fish with Lungs HE evolution of life on earth was marked by two great turning points— the invention of the backbone and the coming out of ocean life onto the land. Evidence of both these events survives in modern creatures—‘‘living fossils” like

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DecEMBER, 1929 GILL SLITS ‘ (INSIDE) ‘ BRAIN 4. STOMACH EGGS LIVER WINDPIPE {TO LUNG) Courtesy The American Weekly INTESTINE POPULAR SCIENCE MONTHLY Anatomy of the lung fish, a surviving example of evolution from water breathing to air breathing. When the water is foul the fish goes to the surface and gulps pure air into its primitive lungs. the remarkable lizards of Australia which resemble miniature copies of the ancient dinosaurs. Geologists have always re- gretted, howeve-, that no actual fossils of the first backbones, or of the first air- breathing fishes, have been found. One reason for this lack, at least in the case of the first air-breathers, was sug- gested recently by Professor D. M. S. Watson, of the University of London. It is probable, he said, that the first transi- tion of ocean life to the land took place around the shores of a continent since sunk beneath the sea. Surviving creatures which show this change from water breathing to air breathing—the so-called lung fishes of the zoologists—are almost precisely the same on the two sides of the South Atlantic Ocean, in Africa and in South America. This fact, Professor Watson said, strongly suggests that the first evolution of these creatures so im- portant for life’s history may have oc- curred on a continent believed to have stood where the South Atlantic now rolls. Much geologic evidence points to the existence, millions of years ago, of this hypothetical South Atlantic continent. It has even been christened Gondwanaland. Many other fossils and living creatures, when studied on the two sides of the Atlantic, indicate the same transition as do the lung fishes. Lung fishes of the South American swamps do not live in the air, but a curious handicap of their homes forces them to breathe it. In the swamps there are seasons at which most of the vegetation dies and decays, mak- ing the water exceedingly foul. No oxygen is left in this water for fish gills to absorb. Accordingly, the lung fish go to the surface and gulp down pure air. While they do not ac- tually have lungs, spongy sacs con- nected with their throats and food canals receive this air and absorb its oxygen into the blood. Even the human lung, physiolo- gists know, is simply an outgrowth from the throat tube originally used exclusively for swallowing food. Thus the lung fish really has the same air-breathing mechanism as human beings but in a more primitive form. Studying the Apes F GREAT interest to psychol- ogy is the recent statement by President Angell of Yale University that the University proposes an ape experiment station in Florida. This will be a part of the new Institute of Human Relations; which is quite fitting, although perhaps not exactly as President Angell intended, since of all human “relations” the apes are the closest and the most interesting Some years ago in Florida, Pro- fessor Robert M. Yerkes, of Yale, studied the young female gorilla named “Congo.” At New Haven, also, Professor Yerkes maintains a colony of apes. The New Haven climate, however, is not friendly to these delicate animals. Even in Florida it proved impossible to keep Congo alive. In the proposed new Florida station every suitable facility will be provided for the health and happiness of these animals, for so like human beings are they that happiness seems just as important to their survival as does bodily health. The importance of all this to the science of psychology is that it begins to dig around psychology’s roots. Not long ago Professor A. L. Kroeber, of the Univer- sity of California, reviewed the mental accomplishments of apes and men. He concluded that the germs of human in- ventiveness, of the use of tools, the idea of competition, and habits of dress and adornment, all were discoverable in living apes like the gorilla and the chimpanzee. Even the beginnings of the religious im- pulse he found to be pre-human. One thing that apes do not have seems to be speech. This is not because they lack the vocal mechanism, says Professor Yerkes, but because some mental defi- ciency prevents the image-forming habit Testing samples of steel with new magnetic appara- tus developed in the Westinghouse Research Labo- ratory. Manganese is essential for modern steel. 55 willed nia The laugh of a chimpanzee. So much like human beings are these apes that happiness seems just as important to their survival as does bodily health. which seems necessary to real language. Of everything that makes a man the apes have something, but not enough. “As our knowledge and understanding of anthropoid life increases,’ writes Pro- fessor Yerkes, ‘‘so also our thankfulness that we are men.” *‘Medicine’’ for Steel ECENT political discussions of the proposed tariff duty on manganese probably will result in increased public acquaintance with this important metal which has commanded less interest than it deserves. (Continued on page 147) How Much Do You Know About Eyeglasses? EST your knowledge with these questions, chosen from hundreds asked by our readers. Answers are on page 153. 1. Why do people have to wear eyeglasses? 2. What is astigmatism? 3. Why does an elderly per- son require two pairs of glasses, one for distance and one for reading? 4. What is nearsightedness? 5. What are toric lenses and why are they any better than the plain flat lenses? 6. How many hours a day can a person use the eyes with- out causing eyestrain? 7. What is the best kind of | reading light for a person who has to use glasses? 8. What is the matter with eyes that are farsighted? 9. Is there any way to cure defective vision? 10. Isa reading glass as good for reading fine type as magnifying eyeglasses? ae a Ge eg on deere et es Sete ATE Sperone ly Doel ereerene Migrate agate Whi wi i Pt

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Fossil Monsters | Have Hunted POPULAR SCIENCE MONTHLY The author with the skull of a horse that died more than 100,000 years ago, found in a California oil field. Left: feet long, DecEMBErR, 1929 Covering an excavated dinosaur, 60 with protective paper and plaster. Indians were still roaming the western plains when the author of this article began his search for the remains of ancient life in America. In sixty years as a fossil hunter he has unearthed more than three hundred prehistoric rep- tiles, birds, mammals, and fishes. Many of the dinosaur monsters of the museums are trophies of his pick, chisel, and dynamite. Now, at the age of eighty, he tells the unique story of his adventures and discoveries. HE warning whir-r-r of a rattle- snake led to the discovery of bones of the largest prehistoric creature ever found; the acci- dental stroke of a geologist’s pick into a slab of sandstone disclosed remains of the ancestor of all sea serpents; and the glint of the sun’s rays on a time- polished tooth revealed one of the first of the several forms of the horse. The skeletons of monster fishes, lizards, birds, and mammals of ages past are hidden in the rocks like gold, and the work of hunting them is always adventurous, often dangerous. The fossil hunter is forever lured by the possibility that in the next cliff he will find the skeleton of some monster never before seen. ; For more than sixty years of my eighty years of life I have been a hunter of big game that lived on earth three to five million years ago. I have dug up and preserved fossil life, from tiny gastropods less than an inch in diameter to dinosaurs seventy feet or more in length. I have found, entombed in stone, a sea-dwelling reptile, an- cestor to whatever sea serpents may have lived since. I have discovered skeletons that be- longed to toothed birds of giant size, and to the various forms of ancient horse which roamed what By CHARLES H. STERNBERG is now the United States. I have carved out bones from the Red River of the North, in Canada, to the sandy shores of Mexico. Once I was walking along the rim of a cliff in the Bad Lands of Wyoming, when 1 heard, seemingly at my feet, the deadly warning of a rattlesnake. I leaped to one side, slipped, fell, slid over the edge of the crag, and came to a sudden stop sitting down on what apparently was a brown boulder, about ten feet from the top. The “boulder” was the shoulder bone of the largest dinosaur ever unearthed. It was nearly eighty feet long, sixteen Skull of a duck-billed dinosaur, found in Wyoming, ready for mounting. The creature, 30 to 45 feet long and 15 to 20 feet tall, cut off branches with its beak and ground them with great molars. feet high at the shoulders, and probably weighed fifty tons or more. Had it not been for the snake on the edge of the cliff, that monster reptile, probably five million years old, would have remained undiscovered. UCH unexpected twists of fate make fossil hunting one of the most fas- cinating games in the world. Searching for prehistoric shells and other marine life on the one-time shore of a great ocean in Kansas, I dropped the geologist’s pick I was carrying and the sharp point ac- cidentally struck a slab of sandstone, flaking off a chip a foot long and half as wide. Beneath, dark brown against the pale yellow sandstone, was the tooth-filled snout of a huge fish. Careful excavation revealed it to be a Portheus molossus, a prehistoric fish four- teen feet long, probably able to destroy any shark alive today. But finding prehistoric speci- mens is not all luck. The hunter must follow certain definite rules and, in the end, the man who looks over the most square feet of ground makes the most im- portant discoveries. The un- expected finds, however, are the ones that stick in a fossil-hunter’s memory after the methodical labor is forgotten.

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DecemMBFrR, 1929 An expert replacing lost bones in the huge skull of a dinosaur. The original bone projects at the right, and at the left is the rebuilt bone. The first rule to guide his search is the fact that the fossils are found only in outcroppings of sedimentary rock, such as sandstone and limestone, which were laid down in the ages in which the hunted specimens lived. The best specimens usually are discovered in sandstone, for the reason that these formations represent ancient shore conditions where life was plentiful and where the animals were buried rapidly. The United States Geological Survey has covered virtually the whole country and its reports show just where outcroppings of the different strata of rock can be found. HE best hunting ground for fossils is in western states where sedimentary rocks are exposed and there is no grass. In his search, the hunter decides what sort of specimens he will look for and then studies the Geological Survey re- ports to see where exposed rocks repre- senting the age in which those specimens lived can be found. He decides upon one region and establishes a central camp from which he searches methodically. Sometimes the specimen he seeks is discovered right at the door of his tent, as was the case in one of my expeditions to Canada. Walled in by rain in the valley POPULAR SCIENCE MONTHLY of a river in Alberta, I bemoaned the fate which prevented me from search- ing for fossil duck-bills, belonging to the family of the huge herbiv- orous dinosaurs. Yet, after the rain had passed and I stepped from my tent, I saw on the face of a near- by cliff, clear cut as with a knife, the complete and almost perfect skeleton of the great and terrible Tyranno- saurus rex, king of all carnivorous dinosaurs. The rain had washed earth and some stone from the front of this wall, revealing the fifty-foot lizard, the terror of the jungles of its day on earth. Though, in general, paleontologists know about where to look for fos- silized remains, every now and then some more adventurous fossil hunter finds a new hecatomb of prehistoric monsters, and perpetuates his name and fame with some new species. For this work, financial remuneration is not large, the best price paid for a well-preserved dinosaur skeleton being about $2,000, while the cost of getting it out is con- siderable. But there is as much adventure hunting fossils as there is in hunting living big game. The present animal life of the world is comparatively well known, while always, just ahead of the fossil hunter, is the probability of discovering some hitherto unknown monster. When a fossil is found the work of the discoverer has just begun. More fragile Courtesy American Museum of Natural History A museum restoration of the terrible Brontosaurus, one of the enormous reptiles which lived in the western part of the United States thousands of years ago. It was 25 feet long and 12 feet tall. Using a power drill to place a steel frame in the skull of a dinosaur preparatory to mounting the skeleton. 57 than glass, buried in adamantine stone through which only a chisel can trace them, the bones, millions of years old, must be extricated as gently as a veteran smoker handles a meerschaum pipe. By patient chipping, frequently requiring weeks, the fossil hunter first traces the form of the buried creature through the cliff or ledge. This is a delicate task, the stone being removed in tiny chips and flakes no larger than a thumb-nail until the skeleton is etched in relief against the stone. Then, some three feet distance from the outermost bones, the rock is cut from the hillside or canyon wall. The cutting is driven beneath until the great natural sarcophagus is free except for small tongues of stone which hold it from slipping. Sometimes dynamite or guapow- der is used in blasting away the rock. Under expert handling, the charges may be shot within a foot of the fragile bones without injuring them. Where the ma- terial surrounding the skeleton is broken sandstone, a coating of shellac is spread over the surface to keep the rock from disintegrating while the work is being done. F THE bones are large, as in the case of the duck-billed Trachodon, the stone is chipped away in some instances until the external surfaces of all the bones are revealed. No attempt is made to remove the stone from the interior of the body cavities, for as soon as these skele- tons are released from their pro- tective covering they break at a touch, and often crumble to fine dust at a breath of wind. A large skeleton is cut into sec- tions weighing from 1,000 to 4,000 pounds each. A skeleton of a Triceratops, a three-horned dino- saur, may be divided into three or four sections, separated at points where bones join, so that when removed from the stone at the museum, the skeleton may be fitted together accurately. | yeh of the sections is covered with dampened rice paper, after which strips of coarse burlap, dipped in flour paste or plaster of Paris, are wrapped over the whole. These strips, three or four inches wide and from one to three feet long, are laid first in one direction and then in another to hold firmly and pro- tect the skeleton during transportation to the museum. The protected sections first are hauled to the main camp of the fossil hunter, where they are boxed in heavy, specially- designed containers. Railroad men han~- dle these cases like glassware, and when they are finally rolled into the museum workshops, whether they be in New York, Paris, or Berlin, the specimens are unpacked by highly-skilled workmen who place the great stone blocks in the order in which they are to be worked by the preparators. One of the most difficult jobs of ex- tracting a skeleton from stone that I ever encountered was tackled in Converse County, Wyoming, where, by a curious accident, I discovered an almost perfect specimen (Continued on page 139) ae Seater ee eet eee As Rs eee eRe pn ene ee sent Sey a f ia it ! +)

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58 POPULAR SCIENCE MONTHLY = ARCHIMEDES Father of Applied Science Travis Hoke, Editor Raymonp J. Brown, Managing Editor Arraur WaKELING, Home Workshop Editor Aurrep P. Lane, Technical Editor Epear C. WHEELER, Associate Editor IsnaEL Doskow, 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. | Trivialities That Count O THOSE not aware of the revolution that recently has been upsetting classical psychology, some of the goings-on of scientists who attended the International Psychological Congress at Yale University, described elsewhere in this issue, may seem trivial. What possible good ean it be, for example, to know that an ape can be taught the difference between a blue and a red colored disk? Or that the drug hashish strangely distorts a man’s perception of an object’s size? Perhaps one of the physical sciences furnishes an answer. There was a time when chemists—then called alchemists— imagined that fire, water, earth, and air were the elements of which all things were made. The ascent from that to modern chemistry has been the direct result of slow, patient accumula- tion of seemingly trivial facts. The minor but acute observa- tion that iron grew heavier instead of lighter when it rusted was enough to overthrow the old theory of “phlogiston”— mythical gas supposed to rush from burning objects—and to lead to the discovery of oxygen. Psychology, baby of the sciences, has learned a trick or two from its older brothers. Its experimenters today, led by the new group of “‘behaviorists,” look with lessening favor upon the elegant theories and assumptions of a generation ago. Instead of hypetheses they want facts. Thus a leader of the behaviorists is reported to have dropped his own baby repeat- edly upon a bed from varying heights to study its actions. No human or animal mannerism is too trivial for a modern psychologist to observe. In some minor action, in the patient accumulation of many data of minor actions, may be found the key to a long-standing riddle of human thought. Soil Erosion Alarmists IKE most propagandists, professional viewers with alarm over the so-called menace of soil erosion are weakening their case by overstatement. More than one hundred billion pounds of plant food are lost to the country’s soils every year by being washed away, says a recent announcement. The estimate is almost certainly far too large, but even were it exact the meaning would be less than is implied. This is like making the unquestionably true statement that more than ten billion cubic feet of air is ruined every year in the United States by being breathed. What of it? The real point is how much air is left. So with the soil. Extremely conservative calculations show DECEMBER, 1929 the United States to possess at least three hundred trillion pounds of soil-contained plant food materials. Of that total the already overlarge estimates of losses by soil erosion equal less than four hundredths of one percent, which fact explodes the alarmist calculations like a pricked balloon. The rapidity with which soil is renewed by natural processes, the raw materials of rock being ground up by things like frost and earthworms and digested chemically through aid of soil, moisture, and weather, is still scientifically debatable. Per- haps the country’s soils are being depleted by wash or cropping faster than they are being restored; perhaps not. Nobody knows. Nor does anybody know with enough assurance to make calculations whether the chemical constituents of the soil will be necessary at all a century hence. It has been seri- ously suggested by competent engineers that agriculture might do better to use naturally foodless soils, like quartz sand, and to supply the needed food materials artificially. The washing away of soil may be a serious matier, undeni- ably, for the individual farmer whose fields are being damaged. There are a few counties, mostly in the southern states, where gullying and hillside scars amount to a community problem. . All this is not hard to stop. Th only necessities are careful and competent farmers, plus a little public education. But this public education is precisely the thing which is not aided, in the long run, by failure to stick to the exact truth. Forward in Building ECENT studies of city noises have shown that the familiar rat-tat-tat of pneumatic hammers that accompanies the building of a skyscraper is one of the most nerve-racking in existence. It is all the more objectionable because it is utterly needless. An article in this issue tells of the increasing use of silent welding methods to erect safe steel buildings. More than forty-five cities already have modified their building codes to take advantage of this modern method. Others cling to their antiquated codes. New York City is among the latter, because when welding was in its infancy fourteen years ago the city officials drafted a code that read, “‘Beams resting upon girders shall be securely riveted or bolted to the same,” and no one since has dared to modify it despite almost daily complaints to the Health Department about noise. All this is singularly reminiscent of the outcries at the close of the last century, when in some quarters it was suggested that pins might not be the best way to fasten trusses together. It took a long time to convince the old-timers that rivets made trusses stiffer than pins. How long will it be before some of our cities awaken to the fact that another step forward has been made? They Are Saying— “After eighty-six years in many lands and among nearly all races I came across only one woman who stammered.”— Major T. H. Hill, British surgeon. \ “We carefully dye our clothes so they won’t show the dirt and count ourselves clean ‘because shirt and collar are fresh from the laundry.”—Dr. C. W. Saleeby, Chairman of the Sunlight League. ‘Sun spots caused the remarkably warm and dry fall weather in Western Europe this year.’””—Henri Memery, director of Talence Observatory, France. “In former times, competition and war were necessary for the securing of food, which could only be obtained by the vic- tors. Now, owing to the mastery of natural forces which sci- ence is beginning to give, there would be more comfort and happiness for all if all devoted themselves to the conquest of Nature rather than of each other.” —Bertrand Russell, English philosopher. “Because of modern smoke conditions, our cities are liter- ally going through the dark ages.’”—Dr. Shirley W. Wynne, Health Commissioner, New York City. ‘Posture is an almost infallible index to character. A person’s salient characteristics can be discerned from the way he holds himself.— Professor William H. Blake, Teachers College, Co- lumbia University. ‘‘History proves that the nation that first takes hold and makes best use of any new development in transportation further advances its prosperity and importance.”—Paul W. Litchfield, President, Goodyear Tire and Rubber Company. _— eee

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DeEcEMBER, 1929 POPULAR SCIENCE MONTHLY 59 POPULAR SCIENCE mame) © 3a. eae OL @) ra N the following pages are presented a month’s record of invention and brief bits about ‘the new, interesting, and unusual things people are doing in all parts of the world. Suction Pipe “Stevedores” Unload Copra Cargoes T THE waterfront in the harbor of Portland, Ore., stands one of the largest plants in the United States for the extraction of oil from copra, the dried meat of coconuts. Large steel freighters tie up at its dock, and their valuable cargoes of copra from Manila, Cebu, or Singapore are unloaded in the shortest possible time through an ingenious system of pneumatic tubes which operate like a vacuum cleaner. When the vessel docks, the receiving ends of two ten-inch pliable steel tubes are dropped into the hold where some 1,500 tons of dried coconut meat have been loosely dumped. Electrically driven machinery in an iron building on the dock is set at work, and the cargo is sucked up at the rate of about forty tons an hour and blown by escaping air to storage tanks in the building. From there it goes by worm con- veyors to the first set of grinders, which break it into bits that look like barley, and is dropped into a jack- eted steel tank. There the mass is stirred while being subjected to 165 degrees of steam heat. It then passes into a battery of rotary expellers, somewhat like huge kitchen meat grinders. Here the oil first begins to flow from the pressed copra. The oil is only partly extracted at this stage, however, and the meat is passed on to another jacketed tank to be subjected to 185 de- gtees of heat. Finally, it is placed in hydraulic presses, whose pressure of 5,000 pounds to the square inch brings out the re- mainder of the oil. The oil is then forced g by pressure through filters / of heavy cloth and, after a treatment for elimina- tion of fatty acids, is ready for commercial distribu- tion. The fibrous portion remains as a cake and is A docked vessel at Portland, Ore., discharging its cargo of copra into the oil-extracting plant at the right. Above: Pneumatic tubes through which the copra is sucked from the hold. Filipinos with their curious ox sled, transporting copra from the drying groves to a native village for shipment. used by millers in prepared foods for livestock. Copra is produced by break- ing up the coconut kernel and drying the pieces in the sun. In this form the product is exported and later undergoes the processes which con- vert it into coconut oil and coco-stearin, the solid portion used in the manufacture of candles. , The coconut oil is useful in the manufacture of marine soap that will form a lather with sea water. It is estimated that 1,000 full-sized nuts will yield upwards of 500 pounds of copra, from which about twenty-five gallons of oil are obtained. a Seeger i ig. Meas ew Rede een y M si Se Si A aa

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New Hot Water Bag Saves the Skin from Burns HOT water bottle designed to protect the tender surface of the user’s skin from burns, even when scalding water is used, has been invented by an Akron, O., manufacturer. This combination of intense heat and painless appli- cation is made possible, it is said, by the fact that the outer surface of the bag is studded with nearly 2,000 “thermo-nubs,” little knobs of rubber like those on a rubber massage brush. These prevent the actual surface of the bottle from touching the skin, and they also permit air to circulate between the skin and the bottle. This air is heated by the bottle; and so dry, hot air is produced. Hot air, because it brings about the rapid opening of the pores es- sential in reducing pain, has been regarded by many physicians as ideal in healing cases of rheuma- tism, sciatica, inflammation, and similar ailments. Moreover, the skin is less susceptible to burns by heated air than by heated water. It is, then, in its production of in- tense healing heat that the advan- tage claimed for this new type of bottle lies. And because there is no need to insert a towel between the bottle and the skin, the makers say, the maximum benefit may be de- rived by the user. The photograph shows the new bottle applied to the shoulder. Locomotive, in Endurance Run, Sets Record LOCOMOTIVE recently broke an endurance record as remarkable, in its way, as any airplane mark thus far set. When Engine No. 4113, of the St. Louis-San Francisco Railway, rolled into Kansas City, Mo., from Birmingham, Alabama, the other day, it had covered 5,144 miles without having its fire drawn. It had eclipsed the old record of 3,500 miles, covered during a twenty-day pe- riod of continuous running between Kan- sas City and Birmingham. POPULAR SCIENCE MONTHLY Penny-in-Slot Doorbell Keeps Hawkers Away T LAST tramps, hawkers, and other nuisances may be discouraged from annoying the housewife. A Dutch in- ventor has devised an inexpensive device that will fit any doorbell and cause it to ring only when a penny is dropped into the slot. Visitors, errand boys, and others who have legitimate business at a house will not be out of pocket, however, for they may receive their coin back as soon as the door is opened to them. High Seat for Customers Aids the Shoe Salesman SUALLY it is the comfort of the cus- tomer that inventors of efficiency devices for stores attempt to safeguard. But one such device that caters to the comfort of the salesman is a new type of seat, designed to eliminate the strain on the backs of shoe salesmen, and recently installed in many shoe shops in Germany. No need for the salesman to stoop over while fitting a shoe on the foot of a customer seated in this new high chair. The customer sits on a high, comfort- able chair to which is attached an exten- sion board that serves as a foot rest for fittings. A ledge beneath the extension, a few inches from the floor, forms a con- venient rest for the shoe box. The clerk may also place one foot upon it, for an “easy” position during fittings. Bandaging with Silver ANDAGES made of silver, instead of cotton, apparently have the power of healing surgical wounds, according to Dr. P. Maritsch, of Vienna University, Austria. The silver, applied in the form of a thin leaf, he reports, seems to have a marked antiseptic value. DECEMBER, 1929 Radio May Trace Mystery of Bird Migration wan do the chimney swifts spend the winter after flying south and disappearing in the region of the Gulf of Mexico? How many stops does the scarlet tanager make on its long semi- annual flight from Canada to Peru and the nighthawk on its weary trek from the Yukon to the Argentine, and where are their favorite ‘‘rest stations”? These and many other mysteries of bird migration which have puzzled scien- tists for years may at last be solved with the aid of radio. A beginning with this new method of investigation was made the other day by an ornithologist in charge of a bird-banding station in East Prussia, Germany. After attaching num- bered bands to the legs of a number of storks, the investigator broadcast a re- quest to European bird lovers for infor- mation regarding the birds. Soon reports started to come in from members of the radio audience. These showed that, five days after their release, the storks had been seen in the Carpathian moun- tains in Czecho-Slovakia. A couple of weeks later they were observed near Messini, in southwestern Greece, having flown about 1,250 miles in that period. Dashboard Spray Puts Out Cigarette Butts OVERNMENT experts report that twenty percent of the $50,000,000 annual loss in forest fires in the United States is due to the carelessness of smokers, and that most roadside fires are caused by passing motorists who toss out burning cigarette or cigar stubs. A new auto dashboard device for extinguishing “smokes,” pictured below, permits motorists to throw away their stubs without starting destructive fires. Pressure on a small plunger at the side of the bowl of the little device squirts water over the end of a cigar or cigarette held above it, extinguish- ing the fire. The stub then can be thrown outside the car or placed in a tray attached to the device. Another model of the invention is designed for the use of hikers or campers. Attached to the belt, it provides a sure method of extinguishing cig- arettes when walk- ing through woods. Pressing a plunger at the side of the receptacle sprays water on the cigarette. arenes

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DeEcEMBER, 1929 Motor Buses Replace Last of Vermont Trolleys ITH appropriate obsequies that in- cluded burning a _ crape-covered street car and playing Chopin’s funeral march, Vermont recently abandoned the trolley car as a means of transportation. The last line in operation, between Burlington and Essex Junction, a distance of sixteen miles, is now closed, leaving the state without a single trolley track that is used. Motor buses have taken the place of the once popular electric cars. Curiously enough, it was in Vermont that the world’s first experiments in con- nection with the application of electric energy to transportation were made. These were conducted at Brandon in 1835, when Thomas Davenport made a number of models of railway motor cars operated by batteries. Other experiments along the same line were made, but it was not until after the electric dynamo had been perfected that practical results were achieved. Numerous attempts to apply the motor and dynamo to traction pur- poses were made between 1870 and 1880. The first overhead system was built in Kansas City, Mo., in 1884, and the first electrical street car line to replace horse cars was started in Baltimore, Md., in 1885. A success- ful eleven-mile trolley system was in- stalled at Richmond, Va., in 1888, and by 1890 nearly 150 American cities had electric lines in operation. Service Set Clamps to the Card Table ARD tables are saved from being marred by stains from wet drinking glasses and burns from cigarettes by a bridge service set re- cently placed on the market. The set consists of a drinking glass holder, an ash tray, and a clamp for holding the shuffled deck of cards made in the form of an arrow point- ing to the next dealer. It is made of a resin composition trimmed with nickel, and may be clamped to each of the four corners of any table. The de- vice not only protects the card table from stains and burns, but prevents drinking glasses from being knocked to the floor and gives the players more “elbow room.” The convenient new service set clamped to a card table. A pointer indicates the next dealer. POPULAR SCIENCE MONTHLY Huge ‘‘Elephant Ear’’ Leaf Is 47 Inches Long ‘“TYLEPHANT’S” EARS are not the exclusive property of elephants but are grown also, as leaves, on shrubs re- lated to the calla lily. These huge leaves are a bright green and, when broken, give out a sticky, white milk. They are often more than a yard long; the one being measured below, grown in California, is forty-seven inches long and thirty-one inches wide. It is said to be the largest in America. The plant which produces these giant leaves is called the taro. It is a sub- tropical plant, native to Hawaii and the Fiji Islands, but is sometimes found in California, Japan, and the West Indies. Its large, starchy roots are edible and Said to be the largest “‘ear’’ in America, this leaf of the taro plant is forty-seven by thirty-one inches. nutritious. In Japan the tuber is eaten as Americans eat potatoes. In Hawaii the root is pounded to a paste and allowed to ferment, in which form it is eaten as the famous Hawaiian “poi.” Young Geologist Unearths Bones of Ancient Whale N THE collection of rare fossils at the Smithsonian Institution, at Washing- ton, D. C., are the petrified -skull and bones of a whale which scientists say are at least 3,000,000, and perhaps 8,000,000, years old, probably the most ancient re- mains of their kind found in America. The skeleton was discovered at Prince Frederick, Md., not long ago, by America’s youngest geologist, William L. Jones, of Baltimore, a seventeen-year-old member of a Johns Hopkins geological survey party. It took five days’ digging to un- earth the huge bones. The skull alone is seven feet long and it is estimated the entire monster measured thirty-six feet. 61 Round Playing Cards Are the Latest OUND playing cards have re- cently made their appearance in England. According to the designer of the new pasteboards, their shape facilitates shuffling and dealing. Six sets of spots and numerals are dis- tributed around the edge of each card, so that the suits and numbers may be read easily regardless of the cards’ position in the hand. On ac- count of the greater width, which makes it almost impossible to hide the cards in the palm of the hand, and the absence of corners, it also should prove an effective weapon against cheating. Circular playing cards, though a novelty to modern card players, are not exactly new; the Persians and Hindus used round cards in their games centuries ago. In Europe, however, where card playing was in- troduced in the Middle Ages, the counters were oblong and about the same size as those used today. Puppet ‘‘Slaves’”’ Found in Graves of Egyptians “(NLAVES” to do their work in the hereafter were buried with the Egyptians of about 2000 B.c. A collec- tion of these substitute workers, or “ushebtis,”’’ were recently placed on ex- hibition in the Egyptian Hall of the Field Museum of Natural History, in Chicago. They are small portrait statues of the de- parted, in mummy form, executed in painted wood, clay, glazed earthenware, terra cotta, and painted limestone. They had the additional function of serving as a home for the souls of their dead models. The earliest conception of heaven among the Egyptians, who since the Stone Age engaged chiefly in agriculture, was a farmer’s paradise, where grain grown by the souls of the dead would reach a height of twelve feet. Later, under the influence of priestcraft, this conception changed to one of a lazy man’s paradise where all necessary toil was to be done by magic substitute laborers. The ushebtis were placed in small coffins of their own.

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62 REMARKABLE new section of the Pan-American Highway, which eventually will connect Alaska and South America, is being opened in Utah. Through the “bad lands” of the south- western part of the state, the roadway stretches for nearly twenty-five miles, in one place burrowing for a mile and one eighth through the solid rock of a moun- tain chain. This tunnel is said to be the longest tube for the exclusive use of auto- Rattlers’ Den Dynamited, but Snakes Survive RATTLESNAKES’ lair that con- tinues to be inhabited by scores of reptiles, despite the fact that it has been dynamited several times, was found some weeks ago near Wheeler Park, Nevada, by E. Raymond Hall, curator of mammals in the University of California Museum of Vertebrate Zoology. In proof of the existence of the den and in confirmation of hitherto unsubstantiated stories that rattlers live in colonies, the scientist re- turned to Berkeley, Calif., with twenty- five snakes he and an assistant had shot. Before starting for the lair Hall was told by the county game warden that only a couple of days before 149 snakes had been killed there. This wholesale destruction apparently had made little impression on the reptiles, for when the hunters arrived at the den, Hall reported, they found fifty of them. The lair, a sunken place at the end of a butte about 250 yards from the Pike’s Peak Highway, was discovered five years ago by sheep ranchers. Since then, the hole has been blasted repeatedly with large charges of dynamite, and con- certed rifle and shotgun attacks have been made on the snakes each spring and fall by residents of the near-by town of Ely, but to no avail. Scores of the creatures appear to survive in some subterranean home in the rocks of which the den is evidently the only accessible portion. New Utah Highway Pierces Canyon Cliffs One of six galleries cut from the tunnel through the wall of Bryce Canyon to afford tourists an occasional view. POPULAR SCIENCE MONTHLY . 7 eS ~ Pe od ~ ge gage ™ pear) a 2%. "tae we a et ‘ aa -’ a: '§ ve ~ od Tae i ees A Pa mobile traffic ever constructed outside of a city. The new short-cut route clips more than sixty miles from the traveling distance between Zion National Park and Mt. Carmel for overland tourists. It is eighty- five miles long, compared with the old road distance of 149 miles. At six places in the course of the tun- nel, galleries lead out to the precipitous wall of Bryce Canyon, whose course the Outboard Motor Boat HE novel spectacle of an outboard motor boat leaping from the water and soaring on wings through the air like a flying fish was witnessed at Auburn- dale, Fla., the other day. Speeding up the motor of his specially equipped Sea Horse at a terrific rate, Harrison Fraser, one of America’s greatest outboard pilots and speed demons, accomplished that feat. The Sea Horse is equipped with small air- plane wings arranged in tandem and an upturned tail, to assist her in prolonging the short flights which her momentum DECEMBER, 1929 Interior of the highway tunnel, nearing com- pletion. It is a mile and one eighth long, with paved roadway. The dotted line in the photograph at left in- dicates the course of the tunnel through the cliffs. At its highest point it is 4,000 feet above the canyon bed. tunnel roughly follows. From these van- tage points, travelers may view the white and vermilion cliffs at the other side of the canyon. At its highest point, the tunnel passes through a mountain four thousand feet above the bed of the canyon. The under- ground highway is hard-surfaced through- out, so that tourists may speed from gal- lery to gallery with all the comfort of riding on a city boulevard. Soars above the Waves initiates. Thus she is enabled to skim over the waves in a series of long leaps. The speed craft is driven over the water by a two-cylinder, sixteen-horsepower outboard motor. Fraser is not, however, the first to try equipping a motor boat with wings. A little over two years ago, the Sea Flea, in a trial off the coast of France, took off from the water at a speed of sixty miles an hour and hopped clear of the waves, its nine-foot wings carrying it through the air sixty- five feet at each jump (P.S.M., July ’26, p. 42). The winged outboard motor boat Sea Horse, driven by Harrison Fraser, soaring clear of the water during a trial at Auburndale, Florida.

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—— DecEMBER, 1929 Chemicals Injected into Tree Fireproof Lumber Y INJECTING into living trees a new fire-resisting mineral ‘‘soup,” experts at the College of Forestry at Tharandt, Germany, have produced lum- ber that is said to be strongly resistant to flames. The fireproofing process consists of feeding a thin solution of chemicals to the tree through holes bored in the trunks close to the ground. As the sap rises, the solution rises with it and gradually spreads to all parts of the tree, “mineral- izing” and fireproofing it without inter- fering with its growth. The solution used is formed of compounds of silicon and fluorine and other chemicals. It has been pointed out that forest fires such as destroyed many valuable tracts of timber in various parts of the country during last summer’s drought may be materially lessened and ultimately, per- haps, prevented entirely by this scheme. Successful experiments to produce col- ored woods, carried on in Maine for some time (P.S.M., Aug. ’29, p. 69), employ a similar process. Dye solutions are in- jected into the trunks of the trees and rise with the sap, coloring the wood. African Rivers May Hold Fortune in Ivory HE great rivers of Africa must be mines abounding in a wealth of an- cient ivory, if a new theory explaining the mysterious disappearance of dead ele- phants, advanced recently by Sir William Gowers, governor of the British colony of Uganda, proves correct. Where do elephants go when they die? Naturalists and explorers for years have tried to find the answer. According to legend, the dying pachyderms drag them- selves to some remote elephant cemetery. Such a place, however, has never been found, and neither have the majority of the 2,000 wild African elephants which, it is estimated, die each year. Sir Wil- liam’s theory is that the animals, when old, go to the nearest river to drink, and that most of them drown there. POPULAR SCIENCE MONTHLY Cable Laying Machine Bores under Street Workmen furnishing the pressure to oper- ate the hydraulic ram, shown at the right. NSIGHTLY, torn-up streets, with their prolonged inconvenience to pedestrians and vehicular traffic, are elim- inated by a new cable-laying machine recently tried out in Berlin, Germany. The device is designed to lay underground telephone and electric cables and gas and water pipes without tearing up the pave- ment. A hole at each side of the street is all that is necessary. The apparatus consists of a hydraulic ram and a long piston. The ram, placed in one hole, forces the piston horizontally through the earth underneath the street. When the piston breaks through into the hole at the other side, toward which it is aimed, the cable is fastened to it. The machine is then put into reverse, pulling the cable through the hole made by the piston. The pressure for the ram is gen- erated by four men operating handles like those of a railway hand car. In tests, the device is Said to have “laid” a cable in five hours, the traffic on the roadway above going on _ unin- terrupted in the meantime. Six-Wheel Army Truck Speeds Cross Country NEW six-wheeled army econnaissance truck that needs no antiskid chains to as- sist it up-steep inclines, over sand dunes, and through the roughest terrain was tested re- cently in the vicinity of London, England, by the British army. It proved its ability to cover exceptionally rugged territory in faster time than even the highly efficient trucks now in use. The double set of wheels at the rear afford extra tractive power. In ad- dition, the rear wheels are mounted in such a way that they can adjust themselves automatically to inequalities in the surface of ground over which they roll. This latest model ls expected to prove particularly useful for service in sandy regions, or over the soft ground of swampy districts. a The flexible mounting of this army truck’s rear wheels gives it maximum traction over rough ground. eee if a The piston, pushed forward, makes a hole through which it pulls the cable on return trip. Intelligence No Guide to Manual Skill, Tests Show AS who falters in reciting Lincoln’s Gettysburg Address and is in the dark as to when to use “who” or “whom” may surpass his smarter brother in con- structing a kite or fixing a toy engine. That, in substance, is the conclusion of Dr. Frieda A. Kiefer, a psychologist of Watertown, Mass., who tested the man- ual dexterity of two groups of children, ranging in age from eight to twelve years, the other day. One group consisted of ninety-five boys and girls of superior in- telligence; the other of ninety-seven children of normal mentality. In none of the experiments did the bril- liant youngsters exceed those of average intelligence in manual skill. The tests were designed to bring out various types of physical ability. Strength of grip was measured with a galvanometer. The rapidity with which a child could tap a telegraph key was determined with a Morse instrument. Steadiness of the hand was measured with electrical de- vices, and ability to control the hand was demonstrated with a stick which had to be moved a certain distance along a rod and stopped repeatedly at the same place.

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POPULAR SCIENCE MONTHLY Testing the Strength of a Stage Whisper OW loud should a stage whisper be? A device recently displayed in the Museums of the Peaceful Arts, in New York City, attempts to give an answer by actual tests. A whisper that will carry to the back rows of an empty theater may be much too soft to be heard so far when the theater is full, for the audience acts as a sound-absorbing medium. The new instrument is designed to help directors in their difficult task of gaging just the right strength for the actors’ whispers. It is a long and narrow box containing two corridors, one of bare wood to dupli- cate conditions in an empty theater, the other fitted with sound-absorbing mate- rial to represent a full “house.” The actor speaks at one end of the box, the auditor sits at the other. A door at Whispering into the box, whose sound - absorbing walls duplicate conditions found in a filled theater. the end of each corridor per- mits first one and then the other to be used. Thus the difference between an un- hampered whisper and a sound-proofed one may be tested on a small scale. The results gleaned from experiments with this in- strument should furnish directors with a clue as to the results that they may expect under different con- ditions in the theater, and should greatly assist them in giving instructions to their actors. Cathedral Windows Restored by “Shaving” HAVING chemical “whiskers” from cathedral windows by means of ordi- nary safety razors is the unusual method recently adopted to restore stained glass panes in England. Not long ago, Dr. Alexander Scott, of the British Museum, examined the windows of Wells Cathe- dral, in Somerset, and found that sulphtric acid fumes from gas lamps used for illu- mination, combined with dust from the stone with which the building is paved, had encrusted the glass. After a series of chemical and microscopic tests it was de- cided that the priceless windows could best be restored to their original beauty by shaving off the deposits. Used Auto Engine Oil Reclaimed in Tests ig ame rout of the United States Bureau of Standards, at Washington, D. C., have a new method of reclaiming used oil drained from automobile crank cases. The apparatus consists of a still, a condenser, and a vacuum pump connected to a series of containers in which various grades of oil are separated. If the new method proves as successful on a large scale as the tests are said to have been, an important saving in lubri- cating oil, 415,000,000 gal- lons of which is used in the United States in one year, may be effected. Dr. Winslow H. Herschel, of the U. S. Bureau of Standards, with the apparatus devised to reclaim old automobile lubricating oil. DECEMBER, 1929 Electroscope Finds Lost Tube of Radium HEN a small brass tube of radium, valued at $4,000, disappeared from a Los Angeles hospital recently, experts who were put on its trail borrowed an electroscope from the California Institute of Technology to help them find it. The electroscope consists of two _hairlike quartz fibers wrapped with platinum in a container under a high pressure and charged with electricity from a dry cell. The emanations from radium discharge an electroscope and allow the fibers to come together. The search began in the room where the radium was last seen. There the electroscope’s fibers wavered slightly. The lost mineral’s route was traced through the hospital and the grounds to the incinerator. But it had left the incinera- tor. Apparently it had gone to the city dump, so the tracers went there. At the dump the fibers of the electroscope drew together, and the radium was found. The “radium detectives’’ with the electroscope that helped them trail the precious substance. Tribe Has Language That Cannot Be Written PEOPLE whose language cannot be written live in the Fergansk region of Suviet Russia, a Russian scientist re- cently reported to the Soviet govern- ment. They are the Doungans, who to this day possess no written language, although the art of writing was originated thousands of years ago, surviving ex- amples dating as far back as 4700 B.c. The Doungans originally were a Chinese tribe which, about one hundred vears ago, moved to Russia. Their language, based on Chinese dialects, ab- sorbed Russian, Arabic, Turkish, and other words and idioms. The fact that they are Moslems, whose sacred book is the Arabic Koran, is responsible for the inclusion of Arabic usages. Philologists have tried to transcribe the Doungan speech, but failed because some of the sounds are sung in tones of definite musical pitch, for which neither the Russian, Arabic, or other alphabets offer a form of expression. Picture writ- ing of the Chinese fell short because it could not express the Russian and Arabic parts of the Doungan language.

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DeceMBER, 1929 Steamer Sights Swan in Transatlantic Flight “LONE eagle” of the swan family A was seen some weeks ago in mid- Atlantic by the passengers and crew of the steamship Homeric. The big snow- white, orange-beaked bird made a striking picture against the sky as it flew about 100 feet above the sea toward Europe. The swan, like the ship, was about 1,000 miles from the nearest land, but it appeared untired and did not seek refuge aboard the liner. Though swans are mi- gratory birds and travel south in winter, they are rarely if ever seen over the ocean. A peculiarity of the birds is that, though they frequent fresh water in summer, they are often found at the seaside in warmer climates during the winter. Indoor Hopscotch Game Played with Marbles HE age-old childhood game of hop- yj gaich can be played indoors with a new toy manufactured by a Lindstrom, Minn., company. The hopscotch toy consists of a base to which is hinged a “springboard” with five holes in a row to accommodate a marble that does the hopping. The object of the game is to It takes practice to make the marble hop from hole to hole on the board. Indoor hopscotch. jump the marble from one hole to an- other, using the springboard, the winner being the player who reaches the fifth hole first. The first four holes are blocked on the underside, while the fifth is open to allow the marble to drop into a corres- ponding hole in the baseboard and end the “round.” Chained to the baseboard at its free end, the springboard has only a limited arc. Quake Relieves Drought is EARTHQUAKE which caused thousands of dollars damage at Attica, N. Y., recently supplied the town with a much-needed supply of drinking water. It opened some underground streams, which soon filled two reservoirs that had been virtually emptied during the protracted summer drought. POPULAR SCIENCE MONTHLY 65 Old Auto Engine Runs Portable Hay Baler PORTABLE hay baler that will pick up the hay from the windrows and turn out the bales in the field with a minimum amount of labor has proved practical, according to its designer, Arba Brutus, of Pine Village, Ind. On the hay baler frame he has mounted an old Ford engine, with a governor and an oversize radiator. The engine operates the baler, and a loader attached to the rear picks up the hay. Only three “hands” are required to work the machine, as pictured above. One man drives the tractor that pulls the entire outfit; one feeds the hay into the baler; and a boy ties the bales with wire. The speed of the outfit is limited only by -the capacity of the baler. New Evidence That Sunlight Is Electric EW proof that sunlight is an electrical phenomenon comes as a result of recently announced determinations of the speed of electromagnetic waves and of the speed of light, declares Dr. Harvey L. Curtis, physicist of the United States Bureau of Standards. It has long been known that both electricity and light travel at about the same speed— roughly, 186,000 miles, or a distance more than seven times around the earth, in a second. Exact comparisons were lack- ing. Then, in 1907, Professor E. B. Rosa and Dr. N. E. Dorsey, of the Bureau of Stand ards, found that there was an apparent discrepancy between the speed of light and that of electricity of only three parts in 10,000—an agree- ment too close to suggest coincidence. Six years later, F. E. Smith at the National Physical Laboratory in London pointed out a slight error in electrical units employed for these calculations. He obtained a revised figure for the speed of electromagnetic waves that two German physicists confirmed in 1921 within an accuracy of one part in 100,000. Their figure for the speed of electricity was 186,282 miles a second. Recently Prof. A. A. Michelson, head of the University of Chicago’s physics depart- ment, redetermined the speed of light as 186,285 miles a second. So close is this agreement with electricity that Dr. Curtis now declares it an “important confirma- tion” of the electric nature of light. FLEET of two-seater taxicabs of a new and unusual design is soon, it is reported, to invade the streets of They are the inven- London, England. The new taxi. Its sliding front door is within arm’s reach of the driver of the cab. Novel Taxicab Has Sliding Door Entrance tion of William Gowan, of Cape Town, South Africa. The novel feature of the new cab is its substitution of a sliding panel for the usual door that opens outwards. This panel, placed in the front of the passenger compart- ment, may be op- erated by the driver without leaving his seat, or by the pas- senger. An oval window takes the place of the cus- tomary side door entrance,anda handgrip fastened to the side of the body lends assistance to passengers entering the cab.

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Build 35-Foot OATING serenely on the high +4 waves of the Atlantic between i New York and Bermuda, an island ; of steel is expected soon to provide seagoing airplanes with an ocean landing field. Supported by a veri- table forest of air buoys laid out in orderly rows, the world’s first ocean airdrome, 1,200 feet long and 200 feet wide, will rise eighty feet above sea level. A working model thirty-five feet long, constructed under the direc- tion of Edward R. Armstrong, of Holly Oak, Del., designer of the seadrome (P.S. M., May ’29, p. 20), will be given its trial test in choppy water at Cambridge, Md., shortly. Should the test prove successful, a full-sized seadrome will be built along the same lines. Not even the wildest of storms should be able to harm the struc- ture, the inventorsays. Sturdy steel bars run from buoy to buoy, connecting the rows both lengthwise and across, and insure absolute rigidity to the framework, POPULAR SCIENCE MONTHLY while steel cables, in pairs, set at a diagonal slant, form a network that fastens the landing surface to the buoys. The artificial island is planned as the first of a string of eight, stretching to the Azores. Machine Teaches Dancers the “Splits” OBBING up and down like a loose- jointed marionette at the end of a string, the user of a new machine for teaching prospective stage dancers to do “splits” soon acquires proficiency, accord- ing to its inventor, proprietor of a Los Angeles school of stage dancing. The apparatus consists of two little platforms set on a short track, on which they roll freely from the center to the ends, and an overhead rope. Standing with one foot on each platform, and grasping the rope, the dancer gives a slight push, and the platforms roll from the center out to the ends of the track. A pull on the rope lifts the dancer’s body, and her feet pull the platforms back to their original posi- tion. The rope permits the performer to control her movements. The extent of the split is adjusted to suit the user. Airplane and Dirigible Combined in Model N ODD craft, half airplane, half dirigible, may soon be seen winging its way about the sky, if the invention of John Hodgdon, of Long Beach, Calif., proves to be applicable to an aircraft of practical size. The model which he has constructed consists of a_ tri-motored monoplane, above which is added a dirigible bag with its own engine and a four-bladed propeller, giving to the craft a total of four motors. By thus combining airplane and diri- gible, the inventor hopes that the novel machine can take advantage of the static lift of dirigible gases and of the dynamic lift of airplane wings as well. John Hodgdon, Long Beach, Calif., inventor, with his model of a strange flying machine that com- bines a tri-motored monoplane with a dirigible. The envelope, above the wings, also has a propeller. DeEcEMBER, 1929 Left: Workmen con- structing the thirty-five. foot working model of the Armstrong seadrome designed for tests in choppy waters at Cam- bridge, Md. Below: The inventor, Edward R, Armstrong, pointing to one of the air buoys which support the field. Model to Test Ocean Landing Field Signs of Life at Chicago 600 Million Years Ago YSSILIZED animals and plants found in rocks from the site of what is now Chicago give evidence of the existence of a low order of life in that region 600,000,- 000 years ago, according to Associate Curator Henry W. Nichols, of the De- partment of Geology at the Field Museum of Natural History, Chicago, Ill. The rocks of a still more ancient era are deeply buried in the vicinity of Chicago, and their records are obscure and difficult to interpret, he says. “The geological history of Chicago,” adds Curator Nichols, “has been peace- ful and uneventful to a degree only occa- sionally encountered. There have been no volcanic eruptions, no formation and destruction of mountains, and, in short, no geological forces have here acted with that vigor, common elsewhere, which has left traces in broken, folded, and con- torted rocks.” Though the site of the city has been many times submerged by the sea and has emerged again, such processes have been slow and orderly, so that the rocks under the city still lie nearly as horizontal as when they were deposited. “The changes of level which have ad- mitted and driven back the sea have not been great,’”’ Curator Nichols continues. “Only once has the region stood at any great elevation, and at no time have the submerging seas attained any great depths. Even at the present day a depres- sion in the land levels of only 600 feet would again submerge Chicago.”

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Parnes + even DecEMBER, 1929 POPULAR SCIENCE MONTHLY Australia to Have Greatest Arch Bridge EWED from the air, with the panorama of the city for a background, the new arch bridge at Sydney, Australia, is an impressive sight even in its unfinished condition. When completed it will be the world’s greatest arch bridge, with a central span of 1,650 feet (P.S.M., Jan. ’29, p. 56). The aerial photograph shows the approach to the northern side of the bridge, looking toward Circular Quay at the head of Sydney Cove. The Cove, across the mouth of which the bridge is being constructed, is one of the many inner bays into which the intricate harbor- age around Sydney is divid- ed. On the further side of the entrance the steel construc- tion may be seen getting under way, and atop the py- lons on both sides are the creeper cranes used in swing- ing the heavy steel beams in place. The present largest arch bridge is the Hell Gate ridge across the East River, New York, connecting the Borough of the Bronx with Long Island. It has a span of 978 feet. Seal Hunters Make Record Catch of 40,000 Skins EARLY 40,000 girls and women will be able to enjoy the luxury of seal- skin coats or wraps this winter as a result of the record catch of seals made in the Bering Sea last summer. The number of skins collected was 39,253, the greatest harvest in forty years. With the prevail- ing fashion frowning on ample garments, the skin of one seal is sufficient to make a coat for the American woman of average size. Until 1911, promiscuous seal hunting was permitted in Pacific waters, with the result that the herd, which once num- bered millions, dwindled to about 122,000, In that year the United States, Russia, Great Britain, and Japan made a treaty to protect the seal from extermination. According to the latest seal census of the United States Bureau of Fisheries, the herd at present numbers almost 1,000,000, despite the fact that 300,000 pelts have been obtained in the eighteen years of protection. Under the present conserva- tion policy, a constant increase in the herd and annual fur yield is predicted. Test Steel-Paved Streets TEEL as a wear-resisting material for street pavement is to receive a test at Chicago, where an experimental strip ten feet wide and 120 feet long has just been laid. Wavy strips of steel form a wide mesh an inch and a quarter deep similar to a steel floor mat. The mesh is filled in with asphalt, which forms a thin upper covering. Aerial view of the half-finished arch bridge at Sydney, Australia, to be the greatest of its type. areca enn ato 67 Mental Disorders Increase in Spring, Figures Show PRIL and May are the “craziest” months in the year, according to Dr. R. Hopmann, of the University of Cologne, Germany. More people lose their mental balance during these two months than in any other equal period, his report says. Statistics on the fluctuations of nervous diseases, which Dr. Hopmann collected, support his idea that in the spring the human mind is less stable than at other times. Police records, too, are said to show that the number of suicides and crimes of passion is highest during these two months. The reason for such mental disorders, Dr. Hopmann says, may lie in the lack of sufficient ultra-violet in the sun’s rays during the long winter or in the effect of sudden changes in weather upon the system. American Party First to Scale Alpine Peak HE top of Mount Giultschi, a 14,700- foot peak in the Italian Alps, recently was reached for the first time by a party of American mountain climbers, headed by Albert Rand Herron. The same group is planning to scale Mount Elburz, in the Caucasus, which, 18,570 feet high, is the loftiest peak in Europe. One Radio Set Supplies 2,000 Headphones HE entire population of Sing Sing Prison, at Ossining, N. Y., can listen to a radio program at one time, through a hookup designed and installed by one of the prison’s inmates who was an electrical expert before entering the prison. The system connects more than 2,000 head- phones and twenty-one loudspeakers with a central radio receiving outfit. The pro- grams are tuned in on this set, and all inmates listen to the same broadcasting. Although the prison covers several square miles and comprises scores of buildings, the quality and volume of reproduction is remarkably good. The central radio room with its elabo- rate equipment is shown in the accom- panying illustration. At the extreme left may be seen a loop-operated receiver. At the right are the six three-tube audio amplifiers. The first supplies the twenty- one loudspeakers; the others supply the headphone groups numbering 300, 680, 150, 680, and 350, respectively. The amplifier units are in multiple series and are so wired that if one gets out of order the rest will continue to function. Apparatus that supplies prison inmates with radio programs. The designer of the hook-up is seated before: the receiving set at the left. The six three-tube amplifiers are in the two boxes to the right.

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68 POPULAR SCIENCE MONTHLY Movie “Sets” Shifted by Overhead Railway A section of a movie “‘set”’ carried on the over- head railway, operated from a switchboard. N ELEVATED railway for shifting scenery is the latest device for saving time and labor employed by a large moving picture company in Hollywood, Calif. An electrically operated railway, more than two miles long, has been sus- pended in the air between the construc- tion shops and the company’s seven stages. The “cars” of this road consist of tongs that grapple the scenery and are suspended from wheels that run along the overhead track. The miniature “elevated” consists of one main line between the shops and the “sets,” with eight sidings, one to each stage and one to the shops. There are also three passing sidings, so that three iti cars may be operated simultaneously. The cars are controlled from a tower switchboard operated by one man. Only two other men are required. One attaches hook or chain to pieces of scenery in the shops, the other guides these into place on the stages. These three, it is said, do two thirds more work than the eight men One of the railway “‘cats’’—tongs suspended from wheels that run on the two-mile overhead track. and large auto truck formerly employed. Sections of scenery weighing up to 2,000 pounds can be handled, and the carriers are so well balanced that a girl can load or unload them with ease. Revolving Camera Makes Planes Do the — AILING on an even keel, a ship, photographed with a new re- volving camera recently tested in Hollywood, Calif., may seem to moving picture audiences to be rocking violently in the grip of a hurricane. By a few turns of a crank, an airplane may be made to perform i in illusion its repertory of tail spins, loop-the-loops, and other thrilling stunts without actu- ally once departing from a straight- forward horizontal course. And, if such a fantastic effect is ever de- sired for a picture, a whole world may be turned topsy-turvy in a few moments. The novel camera that is said to be capable of producing such sur- prising spectacles is mounted on a laxge wheel within another still larger, fixed on a tripod: Skillful manipulation of the crank that turns the first wheel gives the camera. man control of the rotation or oscillation of the camera so as to obtain the effect desired. Neil Hamilton, movie actor, with the new revolving camera that produces topsy-turvy stunts for the screen. DeEcEMBER, 1929 Plane Breaks Kite String and Spoils a Record HEN George Kent, a fifteen-year- old boy of Clifton, N. J., wound ina thousand feet of twine the other day, he pulled to earth a green kite which is said to have broken the world’s record for an “endurance flight.” It had remained aloft twenty-two hours and twenty-one minutes. The previous record had been a twelve-hour “flight” made by a Passaic, N. J., kite-flyer. At 9:20 in the morning, Kent sent up his Spirit of Clifton. All day and during the night he jockeyed it, keeping it in the air in spite of light winds. At 7:41 the following morning, the breeze died out completely and the flight of the green record-holder came to an end. A few days later two boys of Pensau- ken, N. J., Victor Harris and William Edelman, attempted to beat the record, but their efforts ended disastrously. Their kite had been flying well when a descending airplane cut the string and the kite blew away. Suggests Insect Hunting by Ocean Voyagers NSECT hunting may become a popular pastime aboard ship if the suggestion of Dr. T. D. A. Cockerell of the Univer- sity of Colorado receives the attention of voyagers. On a trip around the world recently, the professor noticed that the bright lights of the ship at anchor at- tracted insects from the shore. Taking advantage of these insect visits he was able to make collections from ports at which he did not land. An interesting collection could be made by travelers with very little effort, he said, adding that ships probably play an important part in the spread of insects throughout the world. New Theater Programs Can Be Read in the Dark HEATER programs that can be read in the dark are used by a London, England, playhouse. They are printed on black paper. The ink used is white and it contains a radioactive element. Seen in the dark, the words glow like the hands of a radium watch. Patrons can find out which members of the cast are playing different parts without waiting until the intermission. The novelty is expected to spread to other theaters if it proves popular with playgoers. Bark of a Rare Cinnamon Tree Worth $4,000 NE of the costliest coats in the world is worn byatree. As much as $4,000 is paid for the white-spotted bark of a variety of cinnamon tree growing in French Indo-China. The tree reaches a height of thirty or thirty-five feet. When it is stripped, the bark is divided into three parts. That from the upper portion of the trunk is valued by nat'ves as a medicine. The home of the tree is the province of Thanh Hoa.

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DecEMBER, 1929 Voleano’s Steam Will Heat Hotel in Hawaii TEAM heat from a volcano will warm guests in the new Kilauea Hotel, on the island of Hawaii, if present plans are carried out. According to Dr. T. A. Jaggar, director of the Hawaiian Volcano Observatory, volcanic steam escaping from four holes drilled in the heated rocks beneath the structure will be carried to a huge boiler to raise the temperature of water which will be piped throughout the hotel. The steam itself will not enter the pipes because it contains corrosive acids that eat the metal. The boiler is to be made of noncorrosive metal. This is only one of many projects for utilizing the heat of volcanoes to warm buildings and develop power. In such widely-separated countries as Iceland, Japan, and New Zealand, volcanic steam is now used to heat houses and to run laundries, Dr. Jaggar reports. Electric power is generated from the steam in California and in Italy. On the island of Ischia, near Naples, gardeners use vol- canic heat to warm the soil of their vegetable beds. Calls East Indian Island an Earthly Paradise LAND where worry, care, and illness are virtually unknown and evil is reduced to a minimum was recently described by Dr. John C. Hill, Director of the Department of Religion, Archeology, and Anthropology of the University of Southern California upon his return from a trip to the East. That happy land is the island of Bali, in the Dutch East Indies, just east of Java in the Indian Ocean. The natives, the traveler reported, are almost perfect physical specimens who live a life in which physicians, rent col- lectors, and policemen play a negligible part. He said they were not only an ex- ceptionally healthy, but also a highly moral, people. The island is about 100 miles long and its population numbers 1,000,000. During his sojourn on the island, Dr. Hill inspected the famous temple of Boro Boedoer, an enormous structure covering nine acres, which was buried 1,200 years ago, and of which five levels or stories are now uncovered. Long-Burning Fires Hold Endurance Records HEN it comes to endurance records, long-lived fires deserve the cham- pionship. A fire in a refuse dump at Rikers Island, near New York City, for example, has resisted for fifteen years all attempts to extinguish it. Yet this is a mere baby compared to the famous Kentucky coal mine fire that burned for half a century and was put out only when a near-by river was diverted into the shaft of the mine. The Kentucky inferno has a rival, now over forty-five years old, in the Hocking Valley Coal Mine region near New Straitsville, Ohio. Started in 1884, this -fire (P. S. M., Aug. ’28, p. 30) is estimated to have destroyed billions of dollars worth of bituminous coal. POPULAR SCIENCE MONTHLY Palatial Hangar Has Novel Folding Doors 69 QUIPPED with the features of the most up-to-date railroad station, the palatial new terminal at the airport of Los Angeles, Calif., now nearing completion, will provide luxurious accommodation for arriving and departing planes with their passengers. One of the novel features of the terminal is the double set of folding doors, extend- ing almost the entire width of the build- ing. Though fitted with huge windows, they are so constructed that they may be folded upwards readily to admit incoming planes. The entrance thus provided’ is sufficiently large to permit huge tri- motored transport planes to taxi in and out of the terminal while carrying their full load of passengers. The design of the building architecturally is California mission style. Its construction has cost the city of Los Angeles several million dollars, it is reported. Auto Balloon-Chasing HASING balloons in automobiles is the latest diversion of French society women. The first balloon-chasing contest was held recently at St. Cloud, and is re- ported to have attracted hundreds of entrants. As fifteen small balloons took the air, the women, in automobiles, set out in a New French Sport pursuit of them, the idea of the sport being to follow by road the route taken by the aircraft and to telephone back to the starting point as soon as a balloon was found to have landed. Already, balloon- chasing clubs, with a membership chiefly of women, are said to be springing up in many parts of France. Old Church Wears Odd Coat of Seaffolding NCASED in a shell of scaffold- | ing, St. Paul’s Chapel, New York City’s oldest church building, located in the heart of its downtown section, presented a curious appear- ance during recent renovating operations. The building was erected in 1764. This year’s repair work included patching the surface of the stone and restoring the steeple, which was. added in 1794. To facilitate the work, a cowl of scaffolding, with an iron framework laid out in rectangles, was con- structed. Seen from a distance the church looked like an example of the latest in modernistic design, its steeple resembling an immense stack of witches’ hats piled on each other with spaces between their brims. Panama Canal Busy HE great locks of the Panama Canal opened and closed for 6,413 vessels, representing twenty- three nations, during the year which ended last June. Of that total, the United States supplied more than forty-two percent, or 2,700 vessels. Covered with scaffolding—St. Paul’s Chapel in New York City, built 165 years ago, undergoing repairs. ae 2 a tf ig se ; é eA

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POPULAR SCIENCE MONTHLY DEceEMBER, 1929 What the New Radio Sets Offer Answering the Questions Most Frequently Asked about the Qualities of the Year’s Best Electric Receivers ECIDING what = - radio receiver to buy a is harder this year than it ever was before. And, curiously enough, the difficulty now is due to the fact that there are so many really fine sets on the market. Cabinet designs have be- come so standardized that dozens of different radio sets varying widely in power, price, and so on look practic- ally alike except for minor details in the finish of the cabinet. Of course the more expensive sets have finer cabinets, but the less expensive outfits are housed in cabinets so carefully built that they give the impression of high quality. In many cases only an expert cabinetmaker can distinguish between them. Some of the important questions PoPpuULAR SCIENCE MONTHLY readers are asking about this year’s radio receivers are answered below. The answers should prove helpful to prospective set buyers. What are the meanings of all the new terms used to describe tone gcuality? OOD tone quality means just one thing—the ability of the radio re- ceiver to reproduce, as perfectly as is sci- entifically possible, the tone produced in the broadcast studio. And that in turn means that the electrical and acoustical characteristics of the receiver are such that every tone frequency is treated in a uniform manner. None should be over- emphasized, none suppressed, and none distorted. Many high-sounding but ut- terly meaningless phrases and words have been coined and applied to radio receivers to indicate that in one way or another they are better than other makes as far as tone quality is concerned. The basic fact remains, however, that a receiver is a piece of mechanical and electrical ap- paratus designed to do just one thing. That is to reproduce as faithfully as pos- sible the air vibrations produced by the artists broadcasting. That function may be called by any name imaginable with- out improving the results. Why are screen grid tubes better? HE screen grid tube, from a theoreti- cal standpoint, is a remarkably effi- cient radio-frequency amplifier. If used By ALFRED P. LANE in a well designed circuit it pro- duces, in a practical fashion, more radio-frequency amplifica- tion than can be obtained by the older type tube. It must be re- membered, however, that the presence or absence of the screen grid tube in the circuit has nothing whatever to do with the tone quality that a ‘radio re- ceiver will produce. Just because a receiver has screen grid tubes does not guar- antee improved tone quality. Thousands of radio receivers that have no screen grid tubes are being manufactured and sold this year, and they will give excellent satis- faction to their owners. If the prospective purchaser is interested only in local recep- tion or he is located where a good antenna can be erected, screen grid tubes will be of no particular benefit. On the other hand, if he is located where it is impos- sible to put up a good antenna and local reception conditions are very unfavorable, then a set using screen grid tubes will help him to bring in stations that he otherwise might not receive. (P. S. M., Aug. ’29, p. 71.) Does power detection give greater distance and more vobume? HEORETICALLY, power detection gives better tone quality simply be- cause it eliminates a certain amount of distortion which takes place with the older type of grid condenser and grid leak method of detection. The difference, however, is hardly noticeable except to the trained ear, and then only when the audio amplifier of the set and the loud- speaker are both of excellent quality. The fact that a set has or has not power de- tection should not be considered for or Testing one of the latest radio receivers in the laboratory of the Popular Science Institute, A close-up of the set being tested—a popular model this year, though it is not designed for the screen grid tubes. against it, provided the tone quality is satisfactory. A power detector is not as sensitive to weak signals as is the conventional grid condenser and grid leak method of detec- tion. This, too, is relatively unimportant. In circuits designed to use power detec- tion the radio-frequency amplification is greater than in circuits not designed to use the new system of detection. In some sets the power detector is coupled directly to a single audio amplifier stage using power tubes. This arrangement inher- ently produces less hum than does the circuit using two audio amplifier stages. In some cases, however, the manufac- turer has taken advantage of the reduced hum to cut down the filter circuits so that the net result is little better than it has been in past years. In any case, modern radio sets are practically hum free in operation. In what way are this year’s sets better than last year’s? UDGING from tests of a number of different receivers, the radio sets pro- duced this year are more sensitive, more selective, and give better tone quality

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DeceMBER, 1929 than last year’s sets. The improvement is perhaps more noticeable in the low- priced sets than in the high-priced ones, simply because there was more room for improvement. i The increased sensitiveness and selec- tivity of this year’s products is due in some cases to the use of the screen grid tube and in other cases to a better design of the radio-frequency circuits used with the type 227 tube. In addition, there has been a notice- able improvement in factory produc- tion methods, so that the individual tuned stages are more accurately synchronized with each other. Do the new sets cost more to operate? HE cost of operation of any radio receiver can be divided into de- preciation, cost of current per hour, cost for tube replacements, and repairs. Depreciation cannot be figured by any ordinary method because a modern radio receiver will last for years. The cost for electric current depends entirely on the number and size of tubes used in the set. If, for instance, a set uses three screen grid tubes, type 224; two heater tubes, type 227; and two power tubes, type 171A, it will use just as much current whether the set costs $100 or $300. In any case the amount of current consumed, as compared with sets of last year of approximately equivalent price, will be only a small fraction greater. If the set uses 245 power tubes the current drain will be somewhat heavier. What is automatic tuning? ey of the receivers on the market this year are so built that the various local stations can be tuned in merely by pressing the proper button. The only ad- vantage, of course, is in the time saved as compared with turning a dial to the proper number. It does not improve the actual operation of the set. Remote control is being featured in at least one case. With this form of con- trol the receiver can be tuned from any point in the room or in any part of the house if the house is wired for the pur- pose. This, too, is merely a convenience that has nothing to do with the set’s reception. What is the advantage of automatic volume control? UTOMATIC volume control is an- other improvement for convenience rather than operation. In one form, auto- matic control is obtained by the use of a special tube in the circuit, so connected that the strength of the received signal changes the plate current flow, and the change in plate cur- rent flow, in turn, changes the grid bias on the radio-frequency stages. The result is that all local stations sound about alike in vol- ume. In addition, a hand control is provided to cut the volume be- low the level to which it is con- trolled by the automatic arrange- ment. What is meant by uniform sensi- tivity? THEORETICALLY perfect radio receiver should be equally sensitive on all wave Inspecting another of the new sets. POPULAR SCIENCE MONTHLY lengths or frequencies. Most radio re- Cceivers in the past have shown greater sensitiveness to signals on the lower end of the wave-length band; in other words, on the higher frequencies. A station re- ceived on 545 meters or 550 kilocycles, for example, usually gave considerably less volume from the loudspeaker than a station received on 236 meters or 1,170 kilocycles. There are two reasons why this situa- To Aid in Choosing a New Radio Set FTER subjecting many of the nationally sold radio sets to careful tests in its laboratory at New York Uni- versity, Popular Science Insti- tute has prepared a list of those found to be highly effi- cient and of good value accord- ing to 1930 standards. This list may be obtained free on request. Readers who wish help ‘in choosing a set or who desire advice as to receivers suited to their needs should give full de- tails. Test measurements on file will provide a basis for real help, providing readers will state what features are most important to them, and the price they are prepared to pay. Requests for the list of approved radio equipment, or for personal help in buying, should be addressed to the Popular Science Institute, 381 Fourth Avenue, New York. This receiver uses one screen grid tube to aid in bringing in distant stations. Housed in a novel cabinet with metal frame and wood panel, this set uses one screen grid tube and several 227 tubes. It also includes push-pull audio amplification. 71 tion existed. First, the radio-fre- quency transformers then used were more efficient on the higher frequen- cies; and second, the natural tend- ency of the tubes to regenerate was greater on the higher frequencies. These conditions still obtain to some extent, but other factors work- ing in the opposite direction have been introduced into the circuit in some cases. The net result is a rea- sonably uniform degree of sensitivity on all wave lengths within the band used for broadcasting. What is the advantage of push-pull amplification? USH-PULL amplification is fea- tured in a large number of the latest sets. The push-pull circuit definitely reduces distortion and there- fore improves tone quality. Briefly, the characteristics of a power tube are such that a small amount of distortion is pro- duced in its operation. In the push-pull circuit the distortion produced in one tube is balanced out by the distortion pro- duced in the other tube. (P. S. M., Nov. ’29, p. 71.) Are the new speakers any better than those of last year? IHE high-grade loudspeakers this year produce no better tone quality than the high-grade speakers of last year, but in the less expensive models there has been a vast improvement. There is less difference in tone quality between a low- priced speaker and a high-priced speaker now than there ever has been in the past. Do the new sets need antennas? INCE the latest sets are, on the aver- age, more sensitive than their prede- cessors, in any given installation a shorter antenna will produce the same results as the longer antenna of previous years. In an unfavorable location where reception is poor at best and the building is of steel with wire lath construction, an antenna still is necessary for really satisfactory re- sults. Of course, conditions vary so that it is impossible to give definite rules. What new improvements may be expected next year? T IS difficult to see how any radical improvements can be made in the lat- est radio receivers. From the standpoint of tone quality, for example, it is extremely doubtful whether anyone except a trained musician could detect the difference be- tween the type of reproduction obtain- able from the best of modern sets and an outfit that was theoretically perfect. In other words, with the best sets of this year it is practically impossible to deter- mine, when listening from another room, whether the music is from a radio set or from actual musical instruments. Future radio receivers may be made even more sensitive and selective than they are at present, but any great im- provement in sensitiveness would be of no use because the static level is, in any case, the limiting factor. Any great in- crease in selectivity can be accomplished only by sacrificing tone quality. _Improve- ments from now on are likely to be. in the nature of mechanical refinements in construction and operation, and of changes in cabinet design.

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POPULAR SCIENCE MONTHLY DeEcEMBER, 1929 Useful Hints for the Set Builder A Handy Radio Trouble Lam How to Silence the Squeals in Screen Grid and Audio Amplifier Circuits —Finding the Limit of Selectivity PIECE of apparatus that is indis- pensable to the dentist may be employed by the amateur radio fan to rig up a handy trouble- shooting lamp. The illustration on this page shows how the device is made by soldering the handle of a small dental mirror to a pencil-type nickel plated pocket flashlight. When .the mirror is held in the proper position, and the flash- light button pressed, it is possible to in- spect any part of a radio receiver which otherwise could not be examined. The light from the flashlight bulb is reflected _ by the mirror onto the work, and at the same time the mirror reflects the image of the part being inspected. The proper angle for the mirror can best be deter- mined by experimentation. Probably the greatest use for this de- vice will be found in inspecting soldered joints. Frequently when a seldered joint appears satisfactory when viewed from the top, an inspection of the bottom with this mirror device will show that the joint is far from perfect and may, in fact, be held together merely by a small piece of rosin that had been used as a flux. This tool will be found helpful also in detecting broken wires and short circuits between two wires or between the termi- nals of a socket and a metal base. Screen Grid Suppressors N THEORY, at least, the screen grid ‘tube is so constructed that there is no internal capacity between the elements of the tube to cause feedback and con- sequent oscillation or squealing. In prac- tice, however, the screen grid tube is not absolutely perfect; and, furthermore, it is extremely difficult to shield a radio set to meet the theoretical requirements. In consequence, screen grid circuits that contain two or more tubes sometimes go into violent oscillation when the knob that controls the volume is turned all the way on. If a screen grid tube is not quite up to standard, or the shielding is not well arranged, or if there is a coupling some- where else in the circuit, the tendency toward oscillation may be so great that it is impossible to attain satisfactory volume. The remedy in such cases is to add grid suppressors. The grid suppressor is a resistance connected in the lead to the control grids of the tube, which in the case of the screen grid tube is the lead to the cap at the top of the tube. Experiments will determine the best value, but in any case the resistance is far higher than that of a grid suppressor suitable for use in a radio-frequency circuit employing a 227 Inspecting solder joints with the trouble lamp, made with a flashlight and a dentist’s mirror. or a 201A tube. Ten thousand ohms or even higher may prove suitable. The in- sertion of this apparently extremely high resistance reduces the efficiency of the screen grid tube’s operation very little. This is because the normal capacity in the grid circuit of the tube is extremely low. A considerable amount of resistance must be used to have any appreciable effect. A B C’s of Radio HE only practical way to convert direct current into alternating currentin | quantities sufficient to operate | one of the new electric type | vadio receivers is to use a rotary converter. -or- motor generator unit. The motor generator con- sists of a direct current motor coupled directly to an alternat- ing current generator. A rotary converter is éssentially the same apparatus built as a single unit. If 110 volts direct current is available, it is possible to pur- chase any one of several types of radio receivers especially de- signed to operate on that cur- rent; but for thirty-two volts direct current, a suitable motor generator or rotary converter must be used, or else the radio set must be run on dry cells for the B supply. Stopping Audio Howls UDIO amplifier circuits play queer tricks at times. An audio amplifier, for instance, may operate for months without trouble and then suddenly pro- duce oscillations ranging from a thumping “putt-putt”’ to a high-pitched squeal. Various conditions may cause this be- havior. The line voltage may increase slightly, the characteristics of the tubes may change somewhat, and so on, Trouble of this kind is most likely te develop in push-pull type audio amplifiers, especially if high ratio transformers are used in the circuit. The safest and most certain remedy is to bridge the secondary winding with a high resistance. The value of this resist- ance may be from a half megohm to 50,000 ohms, depending on the character- istics of the circuit. The resistance should be connected from the grid terminal of the power tube socket to minus B or to ground. In the case of push-pull circuits two resistances are necessary, one for each of the tubes. The mere fact that an audio amplifier | does not produce an audible whistle or squeal when no signal is being received does not necessarily prove that there are no oscillations present. The oscillation may be taking place at a frequency above the range of audibility. Though a whistle of this kind may not interfere with recep- tion, it should be eliminated because the oscillation results in excessive plate cur- rent and the tube overloads more easily. Limits of Selectivity HE theoretical limit of selectivity would be reached by a radio set that would receive on a single wave length or frequency; but if such a set could be con- structed it would be useless for broadcast reception. It would tune so sharply that music or speech would be unintelligible. For broadcast reception it is necessary to have a receiver that tunes over a certain band of frequencies, and when ten kilo- cycles is mentioned as the ideal, this means that a receiver should tune an en- tire band ten kilocycles wide and reject all frequencies outside of the band. The construction of such a receiver is practically impossible. ‘Some sets ap- proach it, but all sets bring in some sig- nals on both sides of the desired band. If the local station to be eliminated is, say, 100 times or so more powerful than a distant station on the adjacent wave length, it is utterly impossible to elimi- nate the local so thoroughly that it can- not be heard.

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DecEMBER, 1929 POPULAR SCIENCE MONTHLY 73 The New Household Inventions This milk can opener also serves as a stopper and handle. Sharp points on a lever hinged to the handle punch two holes in the can. Pressing the lever’s end lifts the points out of the holes for pouring; when released, a spring forces the points back into the holes. [ eee . No danger of pushing the cap into the bottle or spattering milk with a simple new milk bottle cap remover consisting of a prong that digs into the paper cap, lifting it off, when horizontal shaft to which it is attached is moved sideways. Above: Cone-shaped heating coils in the new electric range (in circle at right) can easily be removed for cleaning. Especially appropriate for bridge lunch- eons is a set of new salad or dessert molds. Made in the shape of diamonds, clubs, hearts, and spades, the novel forms offer new possibilities to the housewife who likes to be original in food preparation. Devoid of obstructing legs, a new four- burner electric range, with a generous- sized oven, shown opened, is attached at a convenient height to the kitchen wall. When the eggs are cooked to the proper degree of hardness, a new timer auto- matically lifts them out of the water. Four eggs can be boiled at one time with the device, which can be set to operate after any interval from one to five minutes. This new door wedge will hold a door A new washtub stand that rolls on casters eliminates open without slipping, due to the fact the back-breaking task of lifting and carrying heavy that it is made of rubber. Since the tubs filled with water. The tub can be wheeled material is soft and elastic, it will beneath a faucet and filled; afterwards it can not mar highly polished doors or floors. be emptied by tilting overa floor drain. Once fastened to the stand, the tub need never be removed.

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POPULAR SCIENCE MONTHLY DeEcEMBER, 1929 A Well-Built House Is Cheapest An ‘teditinct Tells How to Save Money by Spending It at the Outset for the Best Materials and Workmanship OB KERSEY saw Ed Townsend sitting off in a corner of the club lounge one afternoon, ex- uding gloom and evidently in need of cheering up. Bob dropped into a near-by chair and offered his friend a cigarette. ‘What’s on your mind, Old Timer?” he asked. “Tt’s that house of mine. I’m just wondering if I wouldn’ t be better off to sell it.’ Bob showed his amazement. “Sell it? When you and Mabel were saying only last week that you were so happy in it you hoped you’d never have to leave?” “Yes, I know; but it’s costing a blamed sight more to live in than I can afford, and it’s keeping me broke. If it isn’t fall. ing apart in one place it’s coming to pieces in another. It isn’t so ancient, either; we’ve been living in it for three years, and it was only seven years old when we bought it. I spent a couple of thousand on repairs and redecorating when we moved in and thought I was through; but whenever I get a little ahead something has to be done to it that cleans me out. “First the gutters and leaders had to be replaced. Then the hot water pipes clogged and I had to put new pipes in the heater. The cellar leaked and had to be lined with damp-proofing. We burn an unholy lot of coal, and even then are not really warm. There are places where the plaster cracks, no matter what I do. Some of the floors were so squeaky that I had to have them relaid. The roof springs a new leak every time it rains, and this morning there was a wet spot on the din- ing room ceiling that the plumber says comes from a leak in a pipe. It’s rusted through, and he tells me that the only thing to do is to rip out all of the pipes and replace them. NEVER would have bought that house if I had known it was so rottenly built. I can’t afford to keep on living there; but I hate to wish it on anyone else. I’m up against it.” Here was a possibility that Bob had not considered. About to build a house himself, he gave thought for the first time to the possibility of repair and maintenance expenses that he might not be able to meet. He lost no time in talk- ing that over with his architect. “Say,” he exclaimed. “What’s this house going to let me in for, anyway? I’ve got money enough to build it, but how can I tell whether I'll be able to keep it going?” The architect laughed. “Calm down, Bob,” he said, “you’re not going to get into any such trouble as that. I know all about Townsend’s house, and it’s been a surprise to me that he’s lived there as long as he has. It was built by the bps illuminating experiences of the Kerseys in planning the materials for their new home are concluded in this article, in which they learn the economy of first- class construction. In another helpful article next month, Mr. Whitman will tell how to get the most out of electricity in wiring the home for lighting fixtures and labor-saving appliances. By ROGER B. WHITMAN Jenkins’. Pretty flossy people, and when they put up that house they wanted it to outclass everything else. With cash and mortgages they had only about $25,000, and they planned a house that should have cost twice that. They knew nothing about construction, and couldn’t sec the sense of putting money into places where it wouldn’t show. The builder used to come over and tell me his troubles. They insisted-on having extra good hard- wood floors, but to get them they had to leave out the subflooring. It’s no wonder the floors squeak. They bought fancy wall paper instead of good building paper, SECOND-FLOOR ate JOISTS | SINGLE HEADER A typical example of flimsy framing Above: around a large opening, resulting in sagging and cracked plaster. Below: How extra labor and materials give lasting strength and rigidity. and when the wind blows the house leaks like a sieve. Nobody could see the water pipes, they said, so why spend much money on them? Anything that would carry water would be good enough. D IS having trouble with the roof because the Jenkins’ wouldn’t let the builder use rustproof nails. They guessed that bare wire nails would be all right, and now they’re rusting away and the shingles are coming off. The Jenkins’ ran into the same trouble that Ed has. The house costs more to keep in repair than they could afford, so they sold for what they could get, and Ed thought he had a good buy.’ The architect tapped Bob on the knee. “Listen to this, Bob,” he said; “the cheap house isn’t the one that costs little to buy, but the one that costs little to live in. You pay the purchase price only once, but the cost of occupancy goes on as long as the house does. ‘For an example, take your own house. Well built in the usual way, with the walls sheathed, lined with building paper and finished with clapboards or shingles, and with an ordinary roof, you’d burn at least twenty tons of coal a winter to be com- fortable. With insulated walls and roof, metal weather strips and storm sash, you could heat it with fifteen tons at the outside. Insulation would add maybe $350 to the cost of the house, and weather- stripping and storm sash $250 or so more. For that extra $600 you’d pay $30 a year interest; but you’d save $75 on the coal bill. There’d. be less stoking and ash handling, of course; and with a more even distribution of heat and fewer drafts the house would be more comfortable. “There you have a good example of how you can save money by spending it. If you leave out the heat-proofing you make one saving of $600, while if you put it in you save a clear $45 every year that the house is occupied. OU could save money by using a wood shingle roof; but there’d be a repainting charge every few years, and you'd have to put something aside each year against the time when it would need replacing. Roughly, that roof would cost at least $30 a year. A roof of rough as- bestos shingles that look like hand split wood, or of good quality slate, will cost maybe $400 more to build, but unless an airplane lands on it or you have some other accident, you'll never spend a nickel for repair or maintenance. The annual charges for interest on the higher price of the permanent roof will be $20, so you'll more than break even. The house will have higher value, too. “If the Jenkins’ had asked questions they’d have learned that the water around here raises the dickens with ee

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DecEMBER, 1929 galvanized steel. Brass pipe all over would have cost an extra $100 or so, and would have saved Ed Townsend the $600 he’ll have to pay for replacement. The gal- vanized gutters and leaders that were put in lasted only seven years, and Ed told me the cost of replacement with some more gal- vanized was $275. The first cost was $200, so with what Ed spent those gutters and leaders set some- body back $475, plus whatever had been spent for painting. Copper gutters and leaders would have been about $400 higher, but they would still be as good as when they were new. There’s another place where money would have been POPULAR SCIENCE MONTHLY saved by spending it.” “FPVHIS is a slant on building that I’ve never had before,” said Bob. ‘‘I hadn’t realized that what a house costs to live in depends on how it’s built. If I build a wood house I'll have to paint it every few years, while if it’s stone I won't.” “Exactly. Brass- appearance, plated hardware looks fine when new, but in a few months it gets shabby, and it’ll cost more to replace than solid brass would have in the first place. The drip from it will stain the woodwork, too, and there’ll be the cost of repainting. Substantial things cost more than cheap imitations, but they last longer. “When you look at a house as an in- vestment as well as a place to live in, you get a broader view of it. You don’t buy a railroad bond because you like the color of the ink, but because you think that the company issuing it is so solid that the bond will always be worth what you paid for it. Ask yourself the same question about a house, and if you don’t get the same answer, don’t buy it. As far as value goes, Jenkins might just as well have put his money in a wildcat oil well as in that house, and that goes for Townsend, too. “TINHE place where Ed said the plaster was always cracking is the wall over the ten-foot \ opening between the living room and the dining room. I watched it being built. A wall like that, with no sup- port underneath, should have diagonal braces to form a truss; but to save money that wasn’t done, and the weight comes on a couple of two by fours that form the top of the opening. There’s no stiffness to them, and the plaster cracks as they sag and spring. It wouldn’t be so bad with metal lath, be- cause that has enough strength to more or less hold things together; but with wood lath it’s hopeless.” “But where was the Jen- kins’s architect all that time?” queried Bob. “Why didn’t he tell them those things, and show them where they were wrong?” “They didn’t have one. They thought that all an architect does is to draw plans, and they got theirs ready-made from a book. They wanted a few changes, but said that the builder could make them, and their only specifications were for inside and outside finish. They let ‘him do as he liked about everything else. He needed work about then, so he went to it; but with not enough money to do a good job he could give them the show things only by cheapening the other parts.” “Exactly what do you mean by ‘cheapening’ a house?” Bob asked. “Using poor material?” “That, and not using enough material, and poor workmanship. That arch where the plaster cracked is an example. A wall must carry the weight of the parts above, and when you cut a hole in it for a window . ra “SON ag? ~ NE | Ss fs The Jong floor beams for this spacious living room must be big enough to prevent sagging. If the beams are too light the floor will sway and creak. Architect’s designs for an attractive living (above) and library. The comfort to be derived from such rooms depends not so much on their surface however, on durable materials and workmanship, which prove cheapest in the long run. 75 oo or a door, you have to uté 3" — put bracing around it to Sts pr make up for what isn’t there. You do the same with the hole in the floor wheré the stairs go through. A good builder will put a lot of material around those places, and a poor one won’t. The longer floor beams are, the bigger they should be so that they won't sag, and that’s another place where a poor build- er will weaken things. #3 He'll save money for @ himself by using timbers Oe Pee that are too light. They ‘nis won't be stiff enough to carry the weight on them, and the floor will poourioy,, = Sway and creak.” of America “Did you see the story in the paper the other day about a family that moved into a new house, and the piano broke through the floor into the cellar?” asked Bob. “No; but a few years ago I as examined a house where that had happened. The beams were too small and were not braced, and two of them had big knots that took away half of their strength. Do you begin to see, Bob, that as your architect I’m doing more for your house than to lay out the plans? I’m specifying the sizes of the timbers and the way they are to be put together, and telling the builder just what materials are to be used and how he is to use them. When we ask for com- petitive bids every builder who tries for the job will know exactly what is wanted, and be able to figure closer than if he could make a choice between materials or had any leeway in the workmanship. That’s part of an architect’s job, and it’s in just that service that the client should make a profit on the fee.” room “TT SEEMS to me that there’s more to it than that,” commented Bob. “Your fee will be paying me a profit as long as I live in the house, because you will have made it cheap to live in.” “Right; and that brings up some sug- gestions. I’d like to see you put in a fireproof first floor over the cellar—steel beams and concrete. With all the litter that collects in a cellar, and a fire going in the heater and a flame in the hot water outfit, that’s where fires are likely to start; but with a fireproof ceiling it can’t spread to the rest of the house. I figure that you'll be able to do it for about $300 more than ordinary construction. I want you to have a dry cellar, too. Draintile should be laid along the footings, and the outside of the walls swabbed with tar or liquid asphalt. All of the floors will = be double, of course, with the = subfloor laid diagonally and covered with building felt. (Continued on page 154)

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POPULAR SCIENCE MONTHLY DECEMBER, 1929 “— the New Motor Cars Excel By MARTIN BUNN OT time to reline my brakes this morning, Gus?” Kellogg called as he drove up to the Model Garage. “The linings are nearly worn through.”’ “Sure thing!”” Gus Wilson re- plied as he swung the doors open. “Run her inside over near the bench.”’ Kellogg was rated as a good customer at the Model Garage. He handled his car carefully and intelligently, appreciated pains- taking repair work, and, as Joe Clark, Gus’s partner, once re- marked: “He pays his bills in- stead of filing them in the waste basket!” **Do a good job, now, Gus,” Kellogg instructed while the veteran auto me- chanic laid out his tools and placed the jacks. “I like to be able to stop quick and, believe me, when the brakes are right on this bus she’ll pretty near throw you through the windshield. I’d like to see any four-wheel- brake car stop any quicker.” Gus smiled. ‘‘Guess you don’t think much of four-wheel brakes,’’ he observed. “T should say not!” Kellogg snapped. “They’re just a talking point to help ’em sell the junk they call automobiles these days. If you want to see a real auto- mobile, take a look at this boat. No fool fancy business. Just plain good auto- mobile.” ““You’ve had five years of fine service out of it,’ Gus admitted. ‘Taking care of it the way you do, you ought to get thousands of miles more before it’s really worn out. By the way,” he suggested, “would you like to look over the cata- logues of some of the new cars while you're waiting? Joe has a few on his desk. Hey! Joe!” he called to his part- ner, “bring out that batch of catalogues I saw you looking at this morning.” Joe popped out of his tiny office with a handful of gayly colored literature. “Thinking of buying a new boat, Mr. Kellogg?’’ he grinned. X!” Kellogg snorted disdain- fully. “‘I don’t think any of the cars they make now are as good as the one I’ve got. I’m satisfied with it.” “T don’t wonder,” said Gus as he measured a piece of brake lining and cut it to the proper length, “that you think four-wheel brakes don’t amount to much. Lots of cars are running on the road with four brakes in such rotten shape they won’t stop the car as quick as two brakes that work right. But if you ever happen to get behind some bird who has good brakes and he gets into a tight place so ne i ttn, lea From the pages of a catalogue the new cars came to life as Gus, the veteran auto mechanic, ex- plained their fine points and showed where they embody improvements in materials and design. he has to jam ’em on, you’re going to slam into him sure as fate.” “Maybe so,” Kellogg admitted. ‘But how about these four-speed transmis- sions? Seems like a lot of bunk to me. What’s the good of four speeds if you drive in high nearly all the time anyway?” “Tt isn’t the four speeds that count so. much as the fact that you get what amounts to two high speeds,” Gus ex- plained. “Lots of times when you're boiling along a fine road at a good clip you kind of wish the motor wasn’t turning over so fast it sounded like a bumblebee. Then when you get stuck in a lot of traffic or you have to push over steep hills and through lots of mud, you wish that high wasn’t quite so high and second wasn’t quite so low and noisy. The right kind of four-speed transmission takes care of both cases. In high, at high speed, the motor is as quiet as a mouse. In third you can crawl through traffic or plough up muddy, steep hills as Gus Says— FTER you get to know every bump and turn in a road you know when it’s safe to step on the throttle and when you ought to take it easy. But don’t get the idea that no car is ever going to come out of a side road just be- cause one never happened to come out while you were passing. When you go whizzing by a blind crossing you’re just asking the undertaker to have a good look at you. A man is likely to get mighty careless right around his own home town—he ge’s to know it so well he forgets about the chances for accidents. Lots of mighty sad accidents have been caused by backing out of the home garage. Make sure there are no children playing around before you throw in reverse and let in the clutch. easy as rolling off a log—and do it with- out any gear noises either. On long trips the higher gearing saves gas, too.” “If a four-speed transmission will do that,” said Kellogg, “I’m all for it. What about this front-wheel-drive idea?” OUNDS like hot stuff in some ways,” Gus observed. ‘“‘Of course it’s so new that you can’t tell how it will work out for a while yet. There’s no doubt driving through the front wheels makes it possible to get the body down close to the ground. The car ought to ride easier. Taking weight off the rear axle should help. I can remember years ago how smooth-riding the old chain drive cars were. They had a light rear axle, too. But as far as that goes, there’s nothing to stop ’em from getting the same light rear axle with the ordinary rear drive by fastening the differential gear case onto the frame and driving the wheels through universal jointed shafts as they do with the new front drives. “‘Skidding should be less with the front drive and it is great for climbing out of ruts. Then there’s no long propeller shaft to cause vibration if it doesn’t hap- pen to be balanced right.” “You don’t seem to be over-enthusias- tic about the front drive,” said Kellogg. “T said it looks good in a lot of ways,” Gus replied. ‘But what looks good doesn’t always work out in practice. Nobody can say for sure until a couple of thousand cars have seen a few years on the road in the hands of all sorts of drivers. Of course the idea isn’t reaily new. ‘Twenty-five years or more ago there used to be some electric hansom cabs running around the city streets that drove with the front wheels and steered with the back ones. Seems to me the ideal way to (Continued on page 138)

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DecEMBER, 1929 POPULAR SCIENCE MONTHLY 77 |=) ah Operating a Model Railway System By FREDERICK D. RYDER, JR. When direct current is available, it is possible to obtain the low voltage current required by the model railway by the use of a voltage reducer con- sisting of special resistance elements. The vast major- ity of homes, are, however, supplied with 110-volt, 60- proportion to their size, the better cycle alternating current. This is ideal, makes of model railways are, in for it permits the use of a step-down trans- = every detail, as well built as their former wound to supply exactly the re- large prototypes. quired voltages. There is no wasted Nas Power obtained from dry cell power, a necessary evil with the direct "e batteries is satisfactory for oper- current reducer. ‘ (Q)= ation in every respect save one— Moreover, a model railway power sta- ¥ it is very costly. Consequently tion equipped with a transformer con- batteries should be crossed off the forms more closely than most people list as a power source if the house _ realize to actual practice on a real rail- is wired for electric lights. road. If the transformer heats excessively, it is an indication that you are drawing too much current from it. The remedy is to divide the load and use two trans- formers, each one handling part of the load (see the diagram, page 78). Do not attempt to operate two. trans- formers in parallel, as you are almost certain to get in trouble. The locomotive on the model railway, as on the real railway, is at once the most important and the most interesting unit in the entire equipment. On most real electrified railways, the current flows Unfortunately, many have the idea through an overhead wire and is collected that model railways-are similar to other © Lae from this wire by means of pantographs mechanical toys sold to children. Noth- —_—_-qwo types of current collectors that are used on the top of the locomotive. On model ing could be farther from the truth. In on most model electric railway locomotives, railways the best practice is to use an Making up the first section of the ‘“‘Ace Limited”’ prior to sending it out through the yards for its ‘‘clear board”’ run. ty “P'S Fae) Nh ~: aS NS “a Tee = YS MODEL railway is, after all, merely a miniature edition of one of our real railroads. And, subject to the limitations of time and space, the model railway owner is faced with all the problems confront- ing the management of a real railroad. The most important of these problems, once the model railway is constructed, deal with maintaining the power supply, the locomotives, the rolling stock, and the track in first-class condition.

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insulated rail placed between the rails on which the wheels run. A current collector is fitted to the bot- tom of the motor frame in such a way that the small steel or brass rollers are held by springs in good electrical contact with the third, or insulated, rail. The electric current flows between the third rail and the running rails by way of the current collector rollers, the motor, and the driving wheels of the locomotive. The motor consists of a stationarv horseshoe-shaped electromagnet, a rotating armature, a brush plate, and a reversing switch. The armature is fitted at one end with a small gear and at the other with a commutator made of three heavy copper seg- ments. The current flows through the winding on the stationary mag- net and also through the winding on the armature by way of the brushes, which make sliding contact with the commutator. In the finest motors, one of the brushes is of a graphitic carbon composition and the other is of tightly rolled copper gauze. R reversing, a switch changes the direction of current through the armature with respect to the sta- tionary magnet. In consequence, the magnetism in the armature is reversed in polarity and it rotates in the opposite direction. The rollers of the current collector must be kept clean and should be ,™ replaced after long continued use has worn grooves in them and rough- ened the surface so that a good electrical contact is no longer possible. Trouble is almost never experienced with the stationary magnet, except perhaps a loose connection at a terminal wire. Though the armature winding also gives no trouble, once in a while one of the wires soldered to the commutator segments will come loose. When this happens, the motor loses almost all its power and there is severe sparking at the brushes. The simplest remedy is to replace the armature with a new one; but if you are handy with the soldering iron, you can locate the loose con- nection and resolder it. The condition of the brushes and the way they make contact is of vital importance. Whenever you find that a motor runs well in one direction but not so well in the other, the trouble is almost surely in the brushes. The best way to clean the commutator is to use a clean rag on the end of a small wooden stick. Give the commutator a wipe after every few hours of running and occasionally give it a thorough clean- ing with a rag wet with gasoline. The The reversing mechanism showing solenoid, plunger, cam mechanism, and switch plate. POPULAR SCIENCE MONTHLY JREADERS who have model railway problems about which they wish ad- vice may write to Mr. Ryder. Address your letters care of POPULAR SCIENCE MONTHLY, 381 Fourth Avenue,New York. Wheels, axles, and bushings can be lifted out as a unit when the collector plate is removed. Motors consist of a stationary horseshoe electromagnet, arma- ture, brush plate, and switch. gasoline sold in small cans for use in pocket lighters is especially good, because it evaporates clean and leaves no oily residue. Never, under any circumstances, put any oil on the commutator. It should be operated absolutely dry. The carbon brush contains suflicient graphite to afford proper lubrication. In the latest types of model locomo- tives the brushes are held in their tubular containers in such a way that they cannot rotate. In consequence, they quickly wear to a perfect fit against the commutator. In general, if the motor runs poorly with but little hauling power, the trouble is most likely to be a dirty commutator. If the locomotive refuses to run at all or runs in a very jerky fashion, look for a broken or loose con- nection somewhere in the wiring or for a worn-out brush or broken brush spring. The latest thing in model electric loco- DECEMBER, 1929 motives is a motor built so that it can be taken completely to pieces in a few min- utes by the aid of an ordinary screw driv- er. Obviously, the new motors are much easier to clean and repair than the older types. Loose connections are almost an impossibility in these new motors, be- cause all necessary connections are made by way of rigidly attached brass bus bars and spring plungers. The more expensive grades of model electric locomotives are fitted with automatic reverse mechanisms. This mechanism may be removed as a unit from one of the new type locomotives. A solenoid electromagnet pulls a lever into engagement with a cam mecha- nism in such a way that the reversing switch plate is thrown alternately first one way and then the other. Current from the third rail through this solenoid magnet is controlled bya contact on the end of a flat metal plate so hinged that gravity, when no cur- rent is flowing through the motor, pulls the heavy end of the plate down and closes the contact. When the current is turned on, the pull of thesolenoid reverses the switch- ing plate and immediately thereafter the magnetism of the stationary mag- net of the motor pulls down the con- tact end of the metal plate and stops the flow of current through the solen- oid. When the current is shut off to stop the locomotive, gravity swings the metal plate back against the contact so that the solenoid will func- tion when the current is again turned on. The reversing mechanism requires no attention whatever. It should not be oiled at all. If your locomotive develops the unpleasant habit of suddenly reversing itself, or the reverse ‘mechanism seems to falter and stutter, look for trouble with the commutator or collector rollers. The reverse mechanism cannot function properly if the current flow is interrupted at frequent intervals by a dirty commutator or worn collector rollers. Each time the current is interrupted the effect is exactly the same as if you deliberately shut the current off by means of the regular control switch. Additional suggestions on the mainte- nance and operation of model railways, particularly with respect to lubrication, will be given in the next issue. TNSULATE THIRD RAIL _» INTO SECTIONS TO THIRD RAIL OF OTHER SECTION TO THIRD RAIL OF ONE SECTION WITH FIBER ~__} PINS —> RHEOSTATS__»-—=|E TO FEED WIRE oe : OF HALF THE LIGHTS TO FEED WIRE OF OTHER HALF OF TEST LIGHTS, > | VOLTS — (TEMPORARY) TO RUNNING (OUTSIDE) RAILS AND RETURN WIRE OF ALL LIGHTS § 4 IF TEST LIGHTS GLOW, REVERSE CONNECTIONS OF ONE OF THE CORDS TO THE PLUG TERMINALS Test lights for determining phase relation in lines of two parallel connected transformers.

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DeceMBER, 1929 POPULAR SCIENCE MONTHLY e PIONEER of fwo-way Hydraulics Two-way spring control—down and up—is the prin- ciple pioneered, developed and perfected by Houdaille. For 27 years Houdaille Hydraulic Double-acting Shock Absorbers have been demonstrating to the motoring pub- lic the measure of true riding comfort. Appreciation now amounts to demand and today the Houdaille principle is the standard of spring control. During the 27 years of Houdaille Supremacy these exclu- sive essentials have been perfected. 1. The double or balanced piston. 2. The reservoir which automatically replen- ishes the fluid. 3. The air vents which permit the escape of air and make the instrument truly hydraulic. 4. The easy single dial external adjustment. Houdailles are standard equipment on Lincoln, Pierce- Arrow, Jordan, Ford, Stearns-Knight, Nash Advanced Six, Chrysler Imperial, Studebaker President, Graham-Paige, Cord front drive and many European cars. New low prices — $40, $50, $75 and $100 plus installa- tion. Slightly higher west of the Rockies and in Canado. Houde Engineering Corporation, Buffalo, N. Y. DIVISION OF HOUDAILLE-HERSHEY CORPORATION Z HOUDATILILIE h ydraulic double acting Shock Absorber

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er POPULAR SCIENCE MONTHLY 2 tering, if the card is to bea plain one. If you are making a folding card, the board will have only the lettering. This large card should be from three to five times larger than your finished card so that all imperfections will be reduced when it is copied. By careful planning, anyone can do a fair lettering job. It is possible, however, to write out your greeting with a lettering pen so that when it is copied it will look as through you have actually written a personal let- Individualistic, photographic cards that can be made ter. When lettering, keep the tops as forma) or as informal and personal as is desired. OR individual Christmas greetings, photographic cards are ideal in that they can be made to reflect the sender’s personality. One need not be expert in using a camera to prepare - these cards since the photographic work can be done by a commercial photogra- pher and finisher. Either a plain card or a folder may be used. In designing, the aim is to bring the elements of lettering, color, and paper to form a harmonious whole that is characteristic of the sender. Pictures have an especial place on a photographic card. Winter scenes are the most popular, but it should not make much difference what is used providing you link your wording with it and the festival occasion of the holidays. Take any scene that appeals to you and write the greeting around the picture. That is, make up your “copy.” The secret of individualistic copy is ‘Be yourself.” Do not be bound by convention. Write as if you were sending a letter or talking to a friend. The more nearly it is like you, the more personal will be the effect. When your picture has been selected and the copy written, consider the ar- rangement of the card. Make “dummies” of common paper the exact size and kind of the intended card. On these sketch the layout of picture, wording, borders, and decorations. Make the dummies over and over until you arrive at an arrangement that satisfies you. LACE the picture first, then the word- ing, and last the border if you are using one. Keep the arrangement simple. If you find yourself temporarily stumped, look through a number of national adver- tisements and you will probably find a layout in one of them that will help you. As soon as. the layout is satisfactory, you are ready to do the actual work of making the card. It is necessary to pre- pare a large size card which you will later copy with your camera or have a photog- rapher copy for you. This card should be a thin, smeeth board. On it glue an en- larged picture and do the necessary let- and bottoms even and in line. Keep the letters very close together and use uniform spaces between the words. Work to a center line. If you intend to color the initial letter, outline it; do not Applying a spatter effect by running a knife blade across a toothbrush previously dipped in water color. fill it in solid. In the case of handwriting, write as you always do. . Take a picture of your finished card, reducing it so that the size will be that desired. From the negative have as many reproductions printed as you feel you will need. Whether you do the photographic printing yourself or have a finisher do it for you, there are now available DecEMBER, 1929 Christmas Cards by Photography By JOHN STEINKE a number of interesting photographic papers, some with soft, dull surfaces and others with extremely brilliant surfaces like sparkling snow in sunlight. Still other papers can be had in gold, silver, and some colors. If you are making an all photographic folder, you must make certain that you use a photographic paper that folds without cracking. FTER printing, you may want to tone and color the prints. The re- developing tubes are advised for the ton- ing, while a brilliant color effect for the lettering part can be made by putting on a spatter color. Dip an old toothbrush into water color and draw a knife across it. This splatters the color over the print. Red and green, the Christmas colors, are especially effective. Trimming the cards is all that remains to be done, if you are mak- ing plain cards. If a folder is being prepared, use any of the various thin mounting papers, and fold and mount your prints, tipping them on with glue. You can buy many styles of at- tractive envelopes or make your own, if you prefer. For a pattern, open up an envelope of the style you wish to make. From this you can easily prepare a template. Lay out the template on heavy card- board and use this as a guide for cutting the paper with a razor blade. Many attractive patterned tissue papers are available for a lining. Fold the envelope over a cardboard of the inside size of the envelope. Put points of glue along the edges and fold down. After the greeting is inserted, glue the flap in the same manner that you would use in sealing an ordinary commercial envelope. In cutting the paper for the envelopes, use a razor blade and a cardboard template made by copying a commercial envelope. The lining is placed in the envelope blank and then the three sides are glued and folded over.

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DEcEMBER, 1929 POPULAR SCIENCE MONTHLY 81 SS SASS aA ASA ASI SA ASV ASAI SIGS SAS IIA VII §. W. GILFILLAN President of GILFILLAN BROS., Inc. Says: “Our advice to all of our dealers is to recommend RCA Radiotrons for initial equipment and for replacement in all of our radio instruments. We do this because we use them for experiments and tests in the Gilfillan laboratories and find that they have no superior.”’ GAL pti Expert radio engineers advise that all tubes in your radio set be re- placed at the same time—once a year at least. Old tubes left in im- pair the performance of the others. By installing a complete new set of RCA Radiotrons you are assured of balanced performance. RCA RADIOTRON RADIOTRON DIVISION Rapio-victoR CORPORATION OF AMERICA NEW YORK CHICAGO ATLANTA DALLAS SAN FRANCISCO e) ) } ) >) > ) Fe ee NN INS SN ee NAN NN © This seal.on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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Benjamin C. Evans, of Crawfordsville, Ind., at the metal working bench of his extracrdinary home workshop. A mort- gage loan broker by profession, he has made mechanics, particularly woodwork- ing, his hobby. In the foreground is the hollow chisel mortiser and boring attach- ment of his variety saw; behind this is an electric drill press and supply cabinets. POPULAR SCIENCE MONTHLY — z= Man Who Has Every Tool a DECEMBER, 1929 For jig-sawing, Mr. Evans uses a port- able machine placed on the bed of his wood-turning lathe. At the right is a 12-in. sanding disk. The larger machines are a 12-in. drum sander and a circular saw table. All the machines in the shop are motor driven, three 1-H. P., two 1- H. P., and two 4-H. P. motors being required to operate the entire shop. Woodworker HAT amateur mechanic can look at Mr. Evans’ workshop without a feeling of envy? Yet even if most of us cannot hope to have a shop so well equipped, we can emulate Mr. Evans in selecting only high-grade tools and machines, and in arranging them in an efficient and orderly way. Even if your workshop is relatively small, you may have devised some special features that would interest other readers. If so, send a photo- graph or photographs, accompanied by a brief description, to the Home Workshop Editor. Five dollars will be paid for each print that is found sufficiently interesting for publication. + SRO TE EE ae RE A general view of the shop which shows both the amazing varicty of tools and the orderliness of their arrangement. All the cabinets are filled with tools and supplies. The re- volving cabinet at the left holds seventy-two sizes of wood screws. In the center is a 12-in. band saw and immediately in front of it may be seen a reversible shaper, for which Mr. Evans has a large collection of cutters, an adjustable gage, and ahold down. In the background is a wood working bench. At the left is the jointer, in the center foreground the shaper, behind it the drum sander, and in the right background the variety saw table. Behind the jointer is a rack for bits; above is a tool cabinet, a collection of C-clamps and oilers, and a board with a number of shaper cutters and attachments, To the right along the wall is a rack for turning chisels, with cabinets above, and in the corner is the lathe and jig saw. A cabinet for paints, another for hardware and supplies, and a board for drafting instruments can be seen on the far wall.

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DecEMBER, 1929

POPULAR SCIENCE MONTHLY 83

Tae a THE mellow beauty of Early American cabinetry was born not without its trials. Phineas Pigge, personifying the traditional wood worker of Colonial times, was, after all, a human being. Picture, then, his con- sternation on the day he ran out of stain half-way through Col. Eustace’s highboy. Nothing to do but mix more stain. And woe betide him if he failed to match the shade of the previous batch. It was a wizard’s task. Phineas very often failed. And even when he approximated the former color, there were still streaks and laps to contend with. Today, we so admire the useful and the beautiful in Phineas Pigge’s cabinet work that we reproduce it on all hands .. . and with success. Its physical proportions are not difficult to copy. And today we have the advantage of Johnson’s Wood Dye... . uni- JOHNSON'S woOobD DYE

me < 7

THE CRAFTSMANSHIP OF PHINEAS PIGGE form to the last drop in the bottle, to the last bottle in the gross. Its clear, true color penetrates deeply, without streak or lap. Take it from ten different bottles on the same job—the result is always the same, uniform to the last degree. May we send you our expert manual on wood finishing? Professional methods ox obtaining the mellow beauty of Colonial cabinetry, regardless of the wood you use, are explained step by step. And the Johnson’s Wood Dye and Finishes specified may be purchased at your hardware store. Send cou- pon today. Ss Sen JOHNSON & SON "*T he Interior Finishing Authorities"

Racine, Wisconsin SPSPSPOOOH — — POSS SSCOSSOESOS EES GH MEE S. C. JOHNSON & SON, Dept. (PM1i2), Racine, Wisconsin Gentlemen: Please send me, without charge, your professional wood finishing manual. CROSSES ESHEETS EEEEEHEHEEEEHEHE HEHEHE HEH EEEEE SLOSS SOSSSSSSSSSSOSSSSSSSSHSHSSSSSHSSHSPOS OSH HSSHSOSSSSOSOSHOSOSOOOOOOP

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B+ POPULAR SCIENCE MONTHLY DECEMBER, 1929 How to Fix a Balky Garage Door A Spray Gun for Oiling Hard-to-Reach Places—And Other Helpful Suggestions for the Automobile Owner HEN the runway to the garage is practically on a level with the garage floor, even a light fall of snow will interfere with opening the doors the full distance neces- siry to allow the car to drive out of the garage. Furthermore, if the ap- proach to the garage is of concrete and the clearance is small, water get- ting under the concrete will freeze and lift it enough to jam against the bottom of the doors. The illustration of Figure 1 shows one remedy. The bottom of the door is sawed off and replaced with a hinged section which can be turned up to give the door several inches hard to reach, such as the clevis joints in the brake mechanism. Few people like to crawl under a car just to squirt a drop of oil or two from an oil can on a clevis joint. Figure 3 shows how to avoid this trouble. Secure an old discarded plumbers’ torch and remove the wick. Fill it with a mix- - ture of light lubricating oil to which a small percentage of kerosene has been added. You will find that if you pump up a good pressure you can, with this outfit, squirt a fine stream of oil as far as fifteen feet. A little “target practice” at the clearance. If the door rests against a sill which extends across the front of the garage it will be necessary to Fig. 1. A hinged section at the bottom of the door assures clearance in winter. Right: Diagram showing double hinge. make the hinged portion open out- ward, in which case the snow and ice will have to be shoveled away for an inch or two in front of the doors to permit the folding up of the lower portion, as shown. The diagram of Figure 1 shows another method of solving the problem by re- placing the lower portion of the door with a double hinged section which can be NOSE OF VALVE- LIFTER = Fyne | ed — | = PIN WIRE PIN-HOLDER Fig. 2. Replacing a valve pin with the aid of an ingenious holder made of looped iron wire. folded straight up. This avoids all trouble with ice or packed snow unless, of course, the snow is piled higher hole in the valve stem. Frequently part of the mani- fold or some other portion of the motor interferes with the hand. Figure 2 shows a simple rem- edy. Wind a wire pin-holder of iron a) TWOzPART EXTENSION clevis joints and springs will materially reduce the wear and consequent rattle at these points. Squirting oil along the edges of the spring leaves is easy, and ade- quately lubricates the spring. Windshield Gap Closer ANY open cars are so constructed that the windshield is in two wire. Make the loops in the end of the wire just tight enough to properly guide the pin and loose enough so that the holder can be withdrawn, leaving the pin in the hole in the valve stem. The pin will stay in the hole and pull out of the pin-holder if the holder is moved sidewise to cramp the pin in the hole. Handy Squirt Lubricator HE harder it is to get at,a bearing to lubricate it the more likely is the lubrication to be neglected. While the modern automobile is so constructed than the top hinge. Simple Holder for Valve Pin ANY jobs around an automobile are hard to do, not because they are inherently difficult from a mechanical stand- point, but because space is so limited that the hand cannot properly approach the work. that lubrication is as easy as possible, there are many places that still are xy ! | ) y 4 One operation of this sort is that of replacing the valve pin after the valves have been ground. With some types of valve lifters it is very difficult to hold the pin between the fingers and get it in the OIL FROM A DISCARDED TORCH Fig. 3. An old plumbers’ torch converted into a spray gun for oiling places hard to reach. Fig. 4. Right: How to replace the rubber strip across the windshield with celluloid. ~ > eos I = SJ ROUND HOLES IN THE CELLULOID sections. Usually a rub- ber strip is supplied to fit in between the two sections to keep out the rain. This strip, while effective in keeping out the rain, does not improve the car’s appearance and is a disturbing black line across the line of vision. An effective solution of the problem is shown in Figure 4. Two strips of trans- parent celluloid, in length equal to the width of the windshield, are perforated along their center lines with a series of holes. They should be laced in place as shown in Figure 4, pulling the lacing suf- ficiently tight to keep the celluloid flat against the glass. $10 for an Idea ACH month POPULAR SCIENCE MONTHLY awards a prize of $10, in addition to regular space rates, for the best idea sent in for motorists. The winner of this month’s prize is D. L. Siverd, of Commodore, Pa., who suggested the garage door clearance device in Figure 1. Other contri- butions published are paid for at the usual rates.

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DecEeMBER, 1929 POPULAR SCIENCE MONTHLY TUNE IN!

We asked:

ERNO RAPEE and the MOBILOIL ORCHESTRA of 55 pieces every Wednes- \——______ day night over W E A F and associated N B C stations. “What do you notice first about the New Mobiloil?” Motorists answered: ‘It lasts longer’ When the New Mobiloil had been in use sev- eral months, we sent investigators to call on motorists in different parts of the United States and Canada. We wanted their unbiased opinion of this new oil. Our investigators asked: “What do you notice first about the New Mobiloil?” Motorists every- where answered: “ Mobiloil lasts longer.” What is the significance of these three words “Mobiloil lasts longer”? Perhaps they sound unimportant at first glance. But as a matter of fact, they are the most significant words in the science of lubrication. For, in comparing oils of similar “body”, engineers have proved that the oil which lasts longest, also lubricates best. Of course, we already knew the New Mobiloil was the longest-lasting oil on the market. We had given it every scientific and practical test we could devise. Through all hours of steady speedway driving at an average speed of nearly 70 miles an hour, we conclusively proved that the New Mobiloil stands up better and lasts longer under every speed and condition of driving. This is why we can say to you: “The New Mobiloil will keep the first-year feel in your engine, lubricate your engine better — it lasts longer.” VACUUM OLL COMPANY Makers of high quality lubricants for all types of machinery the New <a Mobiloil Keeps the first-year feel in your engine

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86 POPULAR SCIENCE MONTHLY DECEMBER, 1999 KF urnishing the _ Bluenose Deck Second dette 3 in a Series on Building a Schooner Model— Blueprints Are Available with Complete Full Size Drawings By E. Armitace McCann Fishing schooner model Bluenose built by Captain McCann, master mariner and ship model expert. OR those who are thrilled at*the mention of the sea, the building of this small-scale reproduction of the famous fishing schooner Bluenose should prove to be an interesting and pleasant pastime. If you missed the first of these articles (P. S. M., Nov. ’29, p. 79), which dealt with the construction of the hull, you can obtain full size drawings of the completed model with details of each difficult part by sending for Blueprints Nos. 110, 111, The fittings, as shown, are correct in every detail and the accuracy with which they are and 112 (see page 110). made and arranged does much towards making the model an attractive and perfect miniature. Having completed the hull, we are ready to fashion and arrange the deck a square hole in the base to take the There are eight 4-in. deadeyes on each fittings. These operations should particu- bowsprit. Near the top, on the forward _ side of the hull as shown in the deck plan. larly interest those who love the sea, side, is pivoted the arm for the windlass The forward ones are level with the for in planning the deck our imagination — brakes, and above this is the bell, which masts at the deck level and are set close can carry us to the original Bluenose can be made from a pin and a drop of to the rail cap at 14-in. intervals. The with its spray-spattered deck and rails. solder filed to shape. ‘deadeyes are held down with chain plates The fittings and their respective places The windlass barrel has wide cogs in having no channels. They can be made in the deck grouping are shown below. the center in which the pawl catches, by twisting fine wire around the dead- Hawse holes should be placed in the small cogs for the ratchet of the brakes, eyes, leaving short ends slightly apart. hull by boring %-in. holes in such a way curved barrels for the chain, andasmaller Cut % by ¥ in. strips of metal, punch that they come through the deck at an drum for the ropes. The uprights can be — two holes in them, and solder on the ends angle just inside the waterways. A rim cut to shape, bored for the barrel, then of the wire. Then cut notches in the rail can be added by using gesso or other split with a knife and glued together caps and nail the plates to the hull with plastic material. again around the bearings. The extended bank pins. The chain plates are painted In the bow of the model is a samp-_ ends are bored for the pin points that are _ black except for the white stripe. son post, 5g by %@ by % in., which has___ used to fasten the windlass to the deck. The companionway just aft the fore- = =e : —— = 3&5 - 45 =f Tc «~ — VAT rine! 7 ay Ap | EO Qt FH oe — = il sestp PN 5 LAS rat Lm LEZ FFA La EEE TEED nsseostilt | aah Se xen. err ~ BREAK OF DECK. SKYLIGHT MAIN FIFE RAIL 4 r FORE HATCH 1 \ , SAMPSON ma Plan showing position and comparative size of fittings. A Bluenose history can be obtained by sending a self-addressed and stamped envelope with a request for Home Wo-kshop Bulletin No. 2. _

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DecemBER, 1929 POPULAR SCIENCE MONTHLY aw AMAZING MPROVEMENT IN RECEPTION FROM YOUR PRESENT RADIO RECEIVER« 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 Trade-marks each socket. Your dealer has them in all types—including the famous B-H tube for “B” power units. NATIONAL CARBON CoO., Inc. General Offices: New York, N. Y. Branches: Chicago Kansas City New York San Francisco Unit of and Carbon Union Carbide [ijgd Corporation 4-PILLAR SCREEN GRID prcrenty Raytheon Screen Grid Tube, ER 224. The weight of the four large ele- ments in this type of tube makes the ex- clusive Eveready Raytheon 4-Pillar con- struction Y vital y important. © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. 87 WITH NEW EVEREADY RAYTHEON

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mast is a block of wood, cut as shown, the front having a door and the sides being paneled. It is white with a brown door and panels. The skylight aft the companionway is above the galley; it, too, is fashioned from a block of wood and painted white. The six small squares are glass, for which celluloid or photographic film may be substituted. The fore and main hatches are blocks sloped slightly on top and rounded at the corners, with grooves in the top and tiny ringbolts made from wire rings fas- tened down with little staples. The coamings are white and the hatches dark brown. The cabin top is also made from a block of wood, the side lines conforming to the run of the rails. On it, to one side, is a skylight somewhat similar to the one for- 2 ward. At the after end are doors and a } slide. The top, which overhangs the side a a little, is painted brown, while the sides are painted white. The steering gear is a worm and screw a affair inclosed in a box as shown. The 4 shaft of the wheel lies to one side of the ia rudderpost and is at right angles to it, a therefore not horizontal. The wheel may be cut from brass plate or celluloid, or made from wood with brass wire spokes soldered to a hub and shaft. °

FT of the wheel is the water butt, which is a cask shaped from a piece of wood and lashed to two cleats glued to the deck. A pinhead will serve as the bung. The cask cleats and lashings are all painted white. On either side of the wheel are the main- sheet bitts, which are nothing more than posts with pieces of flat metal driven through them. The grating is a delicate thing to make properly. The best way is to take a thin piece of hardwood and make saw cuts halfway through, where the crossbars are to be; then make long cuts length- wise, cutting through where the holes are to be. Cut strips of wood to fill the cross cuts, glue them in, and sandpaper smooth. The grating effect may be simulated, how- ever, by varnishing the wood and draw- ing in the holes with India ink. Two nests of six boats each are carried by the Bluenose. Each nest is made in Preparing ANY kinds of paint coatings for M cement floors are now on the market and are very efficient in if that they act as an attractive finish for : | the floor and also protect the surface to : some extent against the ravages of wear in the form of powdering away and cracking. In preparing a floor for a paint coat, care must be taken that the surface is free of any dirt or grease. Grease spots can be eliminated by scrubbing the floor with a strong solution of washing soda and water after first cleaning up as much as possible with benzene. Cement floors are likely to show streaks of alkali. This coating should be removed or neutralized before the paint is applied. The best way to do this is to use a

POPULAR SCIENCE MONTHLY

DeEcEMser, 1929

Positions of windlass, bow- sprit, fife rail, hawse pipe, and bell. Note the belaying pins in upper part of fife rail.

BITTS eS" Above—Stern arrangement showing wheel box and main shackle. Right— The construction of the deadeyes, boom jaws, and the foresail traveler,

FORE = FIFE RAIL oe oo We = ; 7 ZzZEZz Le, — s2IZ BL MAIN SHEET , WHEEL BOX MAINSAIL: bot BOOM JAWS SHACKLE y RATLINES . EQ ] bed DEADEYE <4 J WATER STRAP \ BUTT (SOLDERED) ‘ee, CHAIN

WINDLASS ill ae BH

one piece by cutting it to the main out- line, cutting V-shaped grooves at the sides and ends, and hollowing out the upper dory and giving it three seats and little stem and stern seats. These nests are lashed to cleats fastened to the deck and at least the upper ones should have a loop of rope at each end to facilitate lift- ing the boat outboard. The boats are brown outside and white inboard. The holes for the masts and bowsprit next can be’ bored. The 5-in. hole for the bowsprit will have to be very carefully made. A small hole should be drilled first and then a larger one made. The hole for the foremast, 3% in. in diameter, is 434 in. from the stem; the hole for the mainmast is 4% in. farther aft. The foremast rakes back at an angle of two in fifty, the mainmast at three in fifty. The fife rails surround the masts. The forward one may be a shade smaller than the main. Glue two square posts into the deck forward of the mast as shown; to these fit a D-shaped piece for the rail, supported abaft the mast by turned posts. Then make an oblong piece with square holes in it to fit over the forward posts. On the outside of each post there is a cleat which should have a sheave (wheel) in it; pins hammered flat will serve for these. Belaying pins are held in these rails as shown, eight in each. These may be turned from brass wire or bought ready made, or plain pins may be used. Paint the rails arid pins white. Almost under the main fife rail are the pumps. O THE little bulkhead at the break of the deck and to the deck forward of the foremast are fastened cleats for the foresail and staysail sheets. Nail as well as glue them because they have to stand a strain. Right aft, at the position shown, are the main sheet shackles (see detail). The shackles and rings project through a slot in a board, just under the level of the upper cap rail. All of this is white. Our schooner will carry two anchors on the foredeck. One is a regular harbor anchor with a loose stock, as shown on the deck plan, the shank being about % in. long. The other is a sand anchor for anchoring on the banks. It is longer and slenderer with wide palms. It will not be Jashed down on deck like the other, so is lashed with half of its wooden stock over- board, as with deep-sea ships. The heavy anchor has a short chain cable, the sand anchor a long one of rope or wire. Next month we will proceed to set up the rigging on our schooner. and Painting Concrete Floors solution of four pounds of zinc sulphate dissolved in a gallon of water. If the floor is at all damp the zinc sulphate will not be effective in neutralizing the alkali, so it will be best to yse instead a solution made by mixing one pound of fluosilicate of magnesium in one gallon of water. Before applying the finishing coat in the form of paint, be sure that the floor has thoroughly dried, because any traces ‘of the washing solution will tend to injure the painting coat. Also remove all crys- tallization from the surface, as the crys- tals will tend to cause cracks and scale in the paint. This can be done by brushing the surface thoroughly. One type of coating is made of cement onalime base. This is also used on stucco and concrete walls. As it must penetrate, it cannot be used on top of concrete previously finished with oil paint. If a concrete surface is first prepared with any one of the standard cement sur- face hardeners, which will eliminate what is called ‘‘suction,” any first-class floor paint or enamel will serve. There are on the market, however, several specially prepared floor paints of the oil and var- nish base type that will give better serv- ice than the paints intended for use on wood floors only. Paints on floors are subjected to extremely hard usage and those covering cement floors even harder wear, since the cement does not offer the cushioning effect that wood does. ~ Cement floors can also be treated by applying one coat of surface hardener and then two coats of floor wax.—G.W.

vais

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—_rs DecemBeER, 1929 How to File Circular Saws POPULAR SCIENCE MONTHLY Told by the World’s Foremost Makers of Saws ISSTON Circular Saws, and all other Disston Saws, are made of Disston Steel, from Disston’s own steel furnaces. The cutting qualities of this steel, and the skill of Disston craftsmen, made Disston the world’s foremost saw makers. You want Disston Steel in your circular saw. There is no substitute for it. This steel takes and holds a keener cutting edge; cuts easier, and stays sharp longer. In great lumber mills, Disston Circular Saws are standard equipment. You will find that you, too, can do better work if you use only Disston Saws in your home workshop. Ask for Disston! Circular Saws and Band Saws, Hand Saws, Hack Saws, and, of course, Disston Files. A tr Files for the Wood Worker Disston Cabinet Files (fine teeth) for smooth- - ing and finishing wood surfaces, easing tight doors 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. eee ~~ Handiest of Pocket Levels For truing up construction work, levelling lves, etc., use a Disston Featherweight Pocket Level. It is the lightest and handiest level made. Length, 9”; weight, 2.0z. Aero- plane aluminum. Three proved glasses. $1.25. For Cutting Dovetails, etc. Wherever the finest possible joint is needed, and for dovetailing, pattern making, etc., use a Disston No. 68 Dovetail Saw. Blade extra thin, with fine teeth. The 8” blade, 17 points to inch, is most popular. $1.60. A Disston Circular Saw on a Portable Bench Machine i > sharpen small circular saws, you need a filing clamp or vise; the proper files, and a saw set, or an anvil and hammer, to spring the teeth. The Disston No. 7 Circular Saw Filing Vise is handiest, taking saws from 4” to 16”. On cross-cut and combination saws, use Disston Taper Files, 6” or 7”; on circular rip saws use Disston Mill Files, 6” or 7”, with one round edge. First joint the saw, getting all teeth same length. Do this by turningsaw backward by handon mandrel, holding emery stone lightly against tops of teeth until all are touched. Then put saw in vise and set the teeth, using a Disston No. 18 Triumph Saw Set (Illustrated; $1.50). Be careful not to carry the set down too far on the teeth. Follow the original set of your saw. Note that one tooth is set to the right and the next to the left. Next file the teeth as near to their original shape as possible. Keep all gullets of same depth and width. Bevel teeth alternately, following original angles. In filing, do not reduce length of teeth: simply bring them up to a sharp point. Bevel on both face and back should be about one- third the length of the teeth. On a combination novelty saw, which cross-cuts, rips, and miters, do not set the raker teeth; set only the scoring teeth. No teeth of a hollow-ground combination saw should be set. Do not bevel raker or cleaner teeth, but file them straight through. Your hardware dealer has in stock, or can get for you quickly, Disston Circular Saws for any machine. DISSTON Makers of ““‘THE SAW MOST CARPENTERS USE” **TheSaw MostCarpenters Use”’ The two handiest saws for the home work- shop are the 26-inch $-point for cross-cutting. and the 26-inch 5 int for ripping. You will st every job. The ular “D-8" Light ights cost $3.45. M. weights .45. Many other styles and sizes to choose from. Band Saws for Better Work Disston “Thin Gauge” Narrow Band Saws are 2 to 3 gauges thinner. They run better on machines with wheels up to 26” diameter. Saw 9’ 8” long, 14” wide, 25-gauge, brazed, $2.03. Other sizes in proportion. Disston Combination Saw This type of Circular Saw, known as a Com- bination Novelty Saw, does cross-cutting, ripping, and mitering equally well. It is either flat ground for general work or hollow ground for smoother cutting. “Disston Small Circular Saws and How to Use Them” is a new Ry Henry Disston & Sons, Inc., Philadelphia, U.S. A. bulletin which tells how to operate and refit saws. It will be of (In Canada, address Henry Disston & Sons, Ltd., Toronto) interest and value to every owner or prospective owner of a small a Please send Bulletin on Circular Saws and other helpful data. electric bench saw outfit. The coupon will bring it to you. Name and Address @ This seal on aa advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. it B | i , i {

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Hints on By HENRY SIMON HEN a mechanic is familiar with the theory of hardening tool steel (see P.S.M. Nov. ’29, p. 94), he naturally asks two questions: How can I obtain the neces- sary practice in judging the hardening colors? What is the best method of arranging the equipment and carrying out the operations used in hardening? This article will give new and simple answers to both questions. To obtain practice in judging colors, it is well to use a number of graduated test pieces, as shown in Fig. 1. These may be made from tool steel odds and ends, but all should be of the same steel, with the kind of steel identified by a stamped number. Ordinary drill rod is an excel- lent material because it requires no clean- ing and will harden in both water and oil. Start with two dozen small pieces, all of the same size and shape as at A. Heat one piece at a time, attentively watching for the change, and quench in water just as the piece seems to gain color again. Test the hardness with a file, as suggested at B. If it is so hard that the file will not cut it, try quenching the piece at what you consider a slightly lower temper- ature. Test again, and continue going down with successive pieces until the file just cuts with difficulty. A shade above this is the proper quenching temperature. When about half the pieces have been hardened in water, try the remainder in oil. This time the “‘héat addendum” is a little harder to judge, because it starts Heat Treating Steel How to Acquire Instrument- Like Accuracy in Judging Hardening Colors—Tricks in Controlling the Process POPULAR SCIENCE MONTHLY DeEcEMBER, 1929 a . Ks ros SSA’ 1500 } 14.0 “4 Fig. 3—A. Wrong oven position. B. Oven placed in dark corner. Fig. 4#— A. Uneven heat- ing caused by poor dis- tribution. B. Uneven heating resulting from fast heating. C, D, and E. The serious results of uneven heating. about 100°F. above the end of the critical range. Remember that, other things equal, it is not possible to get the same steel quite as hard in oil as in water or brine. Although it is poor practice to harden steel more than once, it will be all right to use such test pieces over again three or four times, provided they are cleaned with coarse aloxite cloth before each use. With a few hours of steady systematized practice you will be able to judge just when the critical change takes place. It then remains to develop the judgment necessary for determining the heat allow- ance for work of various sections. Here again, practice may be made short and cheap by making up several sets of graduated trial pieces, something on the order of those shown at C. Follow the same procedure as before, and it will not be long until the eye will have obtained a fair judgment of what the proper quenching FIG.2-A QUENCHED AT @ ALF-HARD --Zg— one . ~___ CORRECT GRAIN QUENCHED AT b f: x magnetism just as the critical transforma- tion is completed, a magnet may be used as a help in ascer- taining it. With proper handling, this point can be deter- mined with all the accuracy of a costly instrument, as indicated at Fig. 2-A. At B is illustrated.a more convenient device —a small bar magnet hung from the end of a brass rod. As the steel emerges from a black-red heat and begins to brighten, the magnet is repeatedly approached, each time being quickly withdrawn, until it is found to be no longer attracted. Such a magnet is a valuable aid to the beginner, and indeed is always a good check to have on hand. It should, however, be used only as a check. Learning to harden by eye is a meaning- less term, however, unless the eye is given a fair chance to tell heat color. This means, for one thing, that the oven must be shaded as carefully as a lathe or miller should be lighted. The oven should be located in some corner of the shop where the light is subdued. Glary, whitewashed walls and un- heat for any particu- lar piece of work should be. Since steel loses its MAGNETIC , WATER HARDENING |_1400-/425° 1425°- 1450", 1450~/475° | OIL HARDENING ae 1475—1500° 1525 /550°,| 1575-/600° FIG.1 MAGNET Fig. 1—A. Drill rod samples. B. Testing for hardness with file. C. Various graduated test pieces, and table show- ing differences in water and in oil quenching. S NONMAGNETIC SAE’ SS AV Fig. 2—A. Test for critical point. B. Sim- ple magnet rigging. . shaded windows near the oven, such as in Fig. 3-A, should be absolutely avoided. As indicated at B, there should be nothing to distract the eye, no matter whether an oven or a flame is used for hardening. As the critical range is approached, the eye should be kept confined to the fire and the shaded surround- ings. Last but not least, light conditions must be right in the oven itself. This part of the problem will take care of itself when the heating is correct. Generally speaking, heating is right when it is slow and uniform. When a cold oven is so heated, all parts of the interior will red- den evenly. The appearance of a fiery fog when the oven is at or near red heat may be evidence of either incomplete combus- tion or of too fast heating. When properly

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DecemBer, 1929 POPULAR SCIENCE MONTHLY not just making things - - Starrett Dividers No. 92 Micrometer No. 320 N OT just making things, buf making them right—that’s the big kick you get out of your shop down cellar when you work with Starrett Tools. Each of the Starrett Tools shown here — and many another be- sides—should be in your tool-chest. They are accurate, practical, dependable. Write for Catalog No. 24“W” showing over 2500 Starrett Tools. ‘Your dealer will be glad to show you the tools you select. THE L. S- STARRETT CO, { World’s Greatest Toolmakers Manufacturers of Hacksaws Unexcelled i Steel Tapes—Standard for Accuracy i ATHOL, MASS., U. S. A. © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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92 fired, the atmosphere in the oven should be entirely clear by the time the oven walls first begin to show color, and it should remain clear throughout the heating. When thus heated, the quenched work will show no appreciable amount of scale or carbon deposit, and it will be in a condition to allow the POPULAR SCIENCE MONTHLY eye to exercise full judgment. Properly done, the heating should ordinarily produce a simultaneous temperature rise in all parts of the work. Uneven heating may be of two kinds, that due to defec- tive heat distribution in the oven as at A, Fig. 4, and that resulting from too rapid heating, as at B, where the heat in the oven is uniform, but the slender portions of the work can- not carry off the heat at the same rate as the heavier ones. Often the one trouble is due to the other, because the forcing of the fire causes the oven to heat unevenly. Whatever the cause, the effect is equally bad; some portions of the work go through the critical change at an earlier moment than the others, as seen at C, and are therefore bound to be above or below the proper quenching temperature at the moment when the remaining por- tions are right. The results in this event are pictured at D and E. In the ptainer kinds of work, such as the stud at C and D, there is the choice of either quenching at the temper- ature of the body and getting the head imperfectly hard, or of quenching at the temperature of the head and having coarse and weak grain in the body. The case is worse with the die at E, where there is a soft spot at a, weak grain and hardening cracks at b, and probably de- formation of the die shape. This brings us to a point which is gen- erally little understood. While it may be entirely correct to introduce a piece such as the almost solid bar a in Fig. 5 into a red-hot oven, it will not on any account do to follow the same procedure with a piece having slender pro- jections like 6. Unless the fire is unduly forced, the work at B will be able to convey the ini- tial high heat fast enough to the internal portions. With piece 5, however, the thin portions are bound to flare up ahead of the heavy ends. These Fig. 5.--A. Proce- A dure depends on shape. B. Uniform heat transmission. C. “Soaking”’ cure. FIG.5 Cc DeceMBER, 1929 Annealing Large Size Castings UILD a forge fire to the depth of 6in. Break the coke up into small pieces, place the work on top of this, and build a fire-brick wall around it. Next, fill in the spaces between the wall and the work with small pieces of charcoal. Heat the material with a very light blast until the charcoal is fully ignited and keep the charcoal burning until the work becomes red- hot. Heat the work for about one hour and keep it well covered with charcoal. Then allow the fire to die down and Fig. 6—A, B, and C. Odd shapes require special heating. D. Method of quenching to overcome uneven hardening. E. When shielding is impossible. portions will therefore be hotter than the rest of the piece, and they will have been subjected to injurious soaking long before the piece is quenched. Such work should therefore be slowly brought up from a black or black-red oven, as indicated at C. It is certain evidence of heating if a thinner portion of a piece shows even a slightly higher heat than the rest. With pieces on the order of 3), it is, nevertheless, desirable at times to apply the heat unevenly. Several more pieces on a similar order are shown at A in Fig. 6. Such intentional uneven heating is the exact reverse of that which ordinarily takes place. Where a part is of some size and of decidedly varying section, the problem insofar as quenching is con- cerned is really the same as if there were several different parts each requiring a different “heat addendum.” A charac- teristic case is illustrated—where it is desirable to heat the thin flange to a lower temperature than the heavy body. The desired result can be properly accomplished by placing the tool with the flange down in a shallow ring that will partly shield it from the heat, as at B, so that the tool in quenching shows a dif- ferential color something like at C. At D is shown a similar plan applied to part a. Such a part with a blind hole, by the way, should be quenched so as to avoid uneven hard- ening. At E, finally, is suggested a simple rough- and-ready way that is sometimes useful in parts which cannot be conven- iently shielded. This consists in removing the work partly or wholly from the fire several times for a brief interval just before the critical range is attained. With skillful handling, the result is the desired temperature and equal hardness of both portions. This is the twelfth in a series of articles by Mr. Simon on shop prob- lems of interest to the machinist and toolmaker. In his next article, which is scheduled for early publication, he discusses some odd uses for familiar, everyday materials in shop opera- tions. These uses are incorporated in kinks that help tolighten many ofthe often difficult jobs around the shop. the work to become cool slowly.—GEorRGE SCHMIDT. Old Bill Says — OU can saw to a curved line if you grind away about half the width of the hack saw blade between holes. Doing good work is only half of being a good mechanic; taking care of machinery and tools is the cther half. Deep holes can be drilled better in the lathe than in a drill press; for as the work re- volves the drill tends to go to the center, while if the drill is revolving it tends to move out, To be sure you are right when grinding a reamer, try it in a piece of scrap metal and check the hole. Do not depend on the tool- crib man too much; check all of your tools for size. Punctuality is one of the most valuable assets a shop man can acquire. Sometimes a file reversed in the filing machine will give better results, especially on thin work. Loosen the chuck jaws when finishing a thin ring or it may not be round when you get through. Grind a few grooves in a hardened set screw to use as a tap for cleaning out holes—as, for example, holes in a die that were packed during the heat treatment. A small pocket mirror is a handy tool. ne ——

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=e SO OO Oe Swe WE Sl et ee DeceMBER, 1929 POPULAR SCIENCE MONTHLY 93 Range Oto 1” by ten- thousandths of an inch. A better way to read ten-thousandths The new Brown & Sharpe Micrometer Caliper No. 24 measures direct by ten-thousandths in a new, easy way. . Ten-thousandths can be read as easily and positively as | thousandths on an ordinary micrometer. Notice the widely spaced graduations on the lower thimble where the ten-thousandths are read. ! Compact in design, easily used, easily read—there are no gears or intricate mechanisms to get out of order. Ask your dealer to show you this new micrometer or write for circular. Dept P. S., Brown & Sharpe Mfg. Co., Providence, R. I., U. S. A. BS Hf iy { “WORLD’S STANDARD OF ACCURACY” BROWN & SHARPE TOOLS IS] This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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® PORTER’S Portable HAND CuTTING TOOLs Porter’s Cutting Tools are de- signed te save backaches and precious time. They are port- able--for use wherever the job happens te be. Their rugged jaws cut clean, multiplying tremendously the pressure ex- erted on the handies. And they may be used in various positions, in spaces otherwise difficult — or impessible — te weri. in. In preduction, maintenance and repair work Porter Tools multiply man pewer. They be- leng in every well-equipped shep, werk bench and tool kit. Send fer illustrated beoklet describing Perter Teols, their Nut Splitting H. K. Porter, Inc. 7 Ashland Street Everett, Mass. | the processes in each | HE curved out- lines of these. attractive hang- POPULAR SCIENCE MONTHLY DECEMBER, 1929 How to bs ing bookshelves make an ideal problem for studying the use of the motor-driven jig saw. In earlier aiticles, the writer has told how to use many other home workshop machines, illustrating case by some piece of furniture. The book- shelves chosen for the present example will prove an addition to the living room or den, or, indeed, may be placed in the breakfast room to hold artistic pieces of china or pottery. In choosing the type of wood to be used, much depends on the finish. My choice would be a cheerful color of lacquer, agree- ing with the color scheme of the room in which the shelves are to hang. White- wood, or even wood taken from packing cases may be used, if close grained. Step No. 1—Making the Patterns. On'a sheet of heavy cardboard 5 by 31% in., lay off 2-in. squares, and from the working drawing on page 96 plot the curves. Cut along the outline with scissors. In like manner lay out and cut the head- piece on a sheet of card- board 5 by 16% in. Step No. 2—Getting Out the Stock. On the jointer, join all edges of the various pieces—the two sides, the headpiece, and the three shelves. Step No. 3—U sing the Circular Saw. On the circular saw, rip the pieces to the cor- Two types of jig saw mechanisms. At the left is the crank motion and at the right the horizontal motion mechanism. Operate a Jig Saw By Wititiam W. KLENKE These bookshelves form an ideal object lesson in the use of the jig saw. The table of the jig saw can be The tension of the blade of this machine can be adjusted by working a lever at the top. rect width and again join these edges on the jointer. Cut the ends off square, making all the shelves the same length. If you havea shaper (shaping machine), use it for putting any desired molded edge on the front of all shelves. Of course, you can easily round these edges, as shown, with a hand plane. Step No. 4—Using the Jig Saw. Jig saws are con- principles. nected with the saw; and as this wheel revolves, the han- dle pushes the saw frame up and down. The maximum speed and power is possible with this type of construc- sliding block or crosshead, which moves the saw frame tilted to any angle, making it | easy to cut an accurate bevel. | © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. structed on two different | The one type | works on a cam or eccentric, | with a little handle or crank | on the side of the wheel con- | tion. The second type is con- | structed with a horizontal |

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DeceMBeEr, 1929 , POPULAR SCIENCE MONTHLY 95 Gee, Dad! Couldn’t We Have Fun with - One of Those Chests ! A set of tools—what do they mean? To the boy—boats and airplanes and swords and heaps of shavings; to Dad—a work- shop—hours of interesting recreation with his boy; to Mother—comrade- ship for her husband and boy—flower boxes for the sun porch—and maybe, repairs to the cupboard door. Boys or men, the fascination is the same. Why not a chest of Stanley Tools for them this Christmas? There are ten dif- ferent sets all packed in sturdy chests. From $10.85 to $90, there is one to fit every purse. There are also twenty-five Stanley Plans giving step by step instructions how to make twenty-five useful household arti- cles. The book, “How to Work with Tools and Wood,” is a practical textbook and guide for tool users. Plans cost 10c each; book, $1.00. Your hardware dealer will be glad to show you these tool chests. Ask him for a copy of Stanley Tool Chest Catalog No. S35e or send to us for a copy. THE STANLEY RULE AND LEVEL PLANT NEW BRITAIN, CONN. STANLEY TOOL CHESTS © 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 DecemBer, 1929 Maydoles... the big “feller” for rough, tough work, balance, power and strength built in. Claws have a grip like a bulldog’s jaw, pull the largest nail or smallest brad with- out slipping. Built to stand the hardest use. the little “feller” for model builders, radio fans—for deli- cate, fussy cabinet work. Perfectly bal- anced, face and sides crowned just enough so you won’t mar your work, built for men who know tools and like to work with good ones. If you take pride in your tools and the work you do, you’l] want these Maydole Hammers in your set. Ask your dealer to show you the size and weight you like. Write us for afree copy of Pocket Hand- book 23°*B’’ containing much handy information. Maydole Hammers The David. Maydole Hammer Co..Norwich NY Some types of portable jig-saw motors can be easily dismantled and effectively used as electric hand drills. | up and down by means of a crank mecha- ' nism. The action of this type is smooth- | help a great deal; and on the con- | sharp chisel is the best tool to- | use. running and extremely quiet. The table of the jig saw is set to an angle of 90 degrees in order to make a square cut. Insert a rather coarse blade in the frame, seeing that the teeth point down. Now adjust the finger for holding down the work to the proper thickness. You will have to work in from both ends on account of the length of the sides; it may even be necessary to do a little hand work if your machine will not reach to the center from both ends. It will pay you to do the jig-sawing very carefully, as it will eliminate a great deal of handwork. Step No. 5—Smoothing Up the Edges. Use a drum sander on all possible curves. Curves that are too abrupt for the sander must be smoothed Sige simpler method, though not so good, for fastening the sides to the shelves, is to make butt joints and screw the job together with round- headed screws. Step No. 7—Turning the Orna- ment. Glue two pieces of stock together with a sheet of paper be- tween, making a piece 11% in. square, and turn the ornament in the lathe. The purpose of the paper is to allow the splitting apart of the two pieces after the turning operation is completed. Step No. 8—Sand papering. Us- ing No. 4 sandpaper, thoroughly sand all parts. Repeat with No. 0 sandpaper. Step No. 9—Assembling. Make a trial fitting between clamps to make sure that all joints fit. Mark the companion pieces as they are to go together. Use plenty of the best glue and clamp the work tightly. Clean off all of the excess glue by throwing fine sawdust over the glue that oozes out of the joints and then scraping it off at once with your chisel. Step No. 10—Cleaning Up. After allowing the glue to harden for at least five hours, carefully remove any excess glue that may still remain. Then sandpaper with No. 0 sandpaper, slightly rounding all sharp edges. The piece will then be ready for the finishing operation. Step No. 11—Finishing. Apply one coat of thin white shellac to-all parts. When this is hard and dry, sandpaper thoroughly with No. 0 sandpaper. Now apply the desired color of lacquer, using a sprayer if available. This article is the fifth of a series in which Mr. Klenke, through the courtesy of various manufacturers, is demon- strating the use of many new home workshop machines of both combina- tion and individual types. "gang with a cabinet file, followed with sandpaper. For some of the Ap) curves, a small spokeshave will 7 ene 4 vex curves and flat pieces, a va A good cabinetmaker uses the file as little as possible. Step No. 6—Cutlting the Dado Joints. Place the two sides to- gether, being sure to have a right and left side. With a try-square, TURNED ORNAMENT SPLIT IN. HALF mark the location of the three shelves. Use a groover of the proper size and fasten this in the circular saw, % in. above the saw table. Groove out both sides. Note that the grooves do not run to the front edge; this }————————__ ee al THIS MEASUREMENT MAY VARY : " ae 5 31% means that you must raise the > stock up so as to start cutting at the right mark. A little hand- work will be necessary at this point. The end can best be cleaned out by boring a -in. hole with a Forstner type bit; make the holes 34 in. deep. The | ™ rounded front edge of the shelf will fit the hole perfectly. A DADO JOINT GLUED % is FRONT VIEW SIDE tt Assembly drawing of the shelves with the curved outlines anil which are to be edema by taping them out on 2-in. squares La - @ This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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DecemBER, 1929 Boys Dollars worth of Fun! — @ i a eae | be aN TL 4 J Sod df a ea a aa me { ’ if \ Giant Block-setting | | \ Crane. il Build it with iH AV | Meccano dl *S dead easy making models with Meccano. There are more than 200 accurately machined parts—a part for % every purpose—of sturdy steel strips, with holes every half-inch apart; Brass Pulleys, Gears, Girders, Axle Rods, Couplings, Nuts and Bolts, Miniature ® Dunlop Rubber Tires and a host of other parts forming a perfectly inter- changeable mechanical system. There is simply no end of fun with Paty a) Lie et Se le POPULAR SCIENCE MONTHLY 97 here’s a Miillion EVERY BOY likes to see, and know why the wheels go round, Meccano answers every question. Self-operating Jib rane Build it with Meccano tually operate when hooked up with the powerful Meccano electric motor, gg which comes with outfits No. 5 and - A. ’ Nos. 20 to 70. =e If you want to become a famous a. . Engineer, commence now. All models bg illustrated in our manuals are built on Trans-Atlantie correct engineering principles. .,, Monoplane FREE—The big Meccano booklet ae for boy engineers tells all about Mec- cano in words and pictures. You can to it, building modelsfrom have your copy free; the simplest to the most MECCANO OUTFITS merely by sending the advanced, including No. 0 Makers 472 Models $1.50 | names and addresses every mechanical in- | NO10 | 727 (| 3891 of three of your pals. vention known to the | No20 ‘ 737 “ 7.50] Write them on a post engineering world. | No30 7 785 ~ 19.00 card, with your name They all work like the No.50 “ 893 . 25.00 and address. Meccano real thing. What’s os r y Company, Inc., Dept. more, ‘on models ac- ee _ — A-1, Mlisabeth, No. Steam Roller Build it with Meccano MECCANO TOY ENGINEERING FOR BOYS Realistic Automobile Chassis Build it with Meccano a’ Es Real miniature Dunlop Tires. For Meccano automobiles. With Outfits No. 5 and Nos, 20 to 70

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'HE latest development : pplied of ap SCIENCE! New Gun Shoots Targets and Small Game without Powder The New CROSMAN REPEATER Deadly Accuracy and Tremendous Power (THE new Crosman Silent .22 embodies the most advanced principles of the use of air as power. It has all the advantages of any first class .22 rifle and these exclusive features: Absolutely noiseless. Never needs cleaning. Low cost ammuni- tion. Amazing accuracy. No bullet splatter. Adjustable power. The Pride of Hundreds of Target Shooters Its marvelous accuracy and perfect balance, its beautiful finish and many outstanding features make the new Crosman Repeater the pride of target shooters every- where and one of the most popu- lar guns for all round sport. For the first time, men living in the cities and the sub- urbs can now enjoy the pleasures of target shooting—in the cellar or back yard. Small Game HUNTERS You can knock ‘em dead in their tracks with this new, high- powered, silent rifle. After you have used the new Crosman Re- peater you will never want any See Spe other small bore , sme. Special for The Only Gun Christmas of its kind Bepeptes ce in the World rifle, packed in The new Crosman holiday een . ™: tccaed ena the ideal Christ ing rifle in the world mas gift. ects in workmanship and material PLAY screen that ‘o = resembles a house c POPULAR SCIENCE MONTHLY DEcEMBER, 1929 Play Screen The screen serves as a play house or as scenery for children’s plays. —— and can be folded for storage when not in use makes an ideal addi- tion toany child’s Christ- for Children a and nailed in place in the order named. The three sections can be lightened considerably by covering the framework with burlap or unbleached muslin in- stead of wall board. However, if this is done, it will be neces- sary tostrengthen theframe. The corners will have to be mitered, lapped, or mortised and tenoned, and the other joints also mor- tised and tenoned. The cover- yor UZZ, Zi by bo Li tp ftl 7, — > Z yb Vil “+ Md We KG Wc mas toys. PS As a school project, its q } construction is such that ~~ = it makes an instructive shop problem; and since | it is almost indispensable | as part of the kinder- garten equipment, the | shop department can re- ceive monetary credit for the work and ma- | terials that were used in construction. The screen illustrated is the design of Jonathan Bright, an instructor at the Academy High School at Erie, Pa. It was awarded first prize in the intermediate woodworking division of a national shop problems competition conducted by the Educational Department of Popular SCIENCE MONTHLY. To construct the screen, any available lumber may be used, but much labor and time can be saved by purchasing.1 by 2 in. white pine in random lengths from any convenient lumber or planing mill. If wall board is used to cover the framework, this can be ordered at the same time. Two sheets 4 by 10 ft. must be purchased, although only one and a half sheets are needed. The first thing to do in constructing the three sections of the screen is to cut the wall board into four pieces, each 4 by 5 ft. Then,pieces of wood are cut to length for the outside frame of each sec- tion, and are glued and nailed to the wall board. All of these pieces are placed even with the edge of the wall board except the bottom piece of the middle section, which is placed 1 in. from the edge. This is done to tan room for the band iron that | is screwed in place later. The crosspieces | forming the top of the door and windows, the pieces under the windows, and the vertical pieces at the sides of the doors and windows, are then fitted and glued ing should be lapped over the edge and tacked on the edge or the back. The frame for the door can be cut, glued, and nailed in place next. In saw- ing out the door, leave in. on all sides for clearance when the door is fitted into place. The braces shown in the corners are made from the short pieces of 1 by 2 in. stock left after the framework is made. They are cut in a miter box to about 6 in. long and are glued and nailed in place. The sections are allowed to stand over- night to give the glue a chance to set before cutting in the door and windows. A series of 1-in. holes are drilled in the two corners diagonally opposite each other in the two window openings and a keyhole saw used to start the cut, sawing close to the frame. After the cut is started it is easy to complete the sawing with a crosscut handsaw. The same method applies to the cut across the doorway. In sawing out the door, be sure to saw close to the pieces forming the doorway, leav- ing any surplus wall board on the door. The center section has a piece of 1 by 34 in. by 4 ft. band iron screwed to the bottom edge across the doorway to hold the two sides of the section rigid. The door is hung withapairof ornamen- tal brass-plated hinges, although any available hinges or butts may be used. Two stops are glued and screwed to the inside on one side of the door frame to

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DecEMBER, 1929 POPULAR SCIENCE MONTHLY 99 Dilla Woodworking Units ““Delta’”’ Electric Handi-Shop A complete Motorized Workshop for craftsmen, including all necessary equipment for Circular Sawing, Wood Turning, Scroll Sawing, Sanding, Drilling, Grinding and Buffing. Practical Design — Dependable Quality — Plus Many Exclusive Features — that’s what you find in every woodworking unit bearing the Delta trade- mark. Craftsmen, artisans, farmers, mechanics—all who use wood in their daily labors or spare-time hobbies / castsection, saibniil, nn: New “Delta” and moderate cost of Delta equip- MOULDING CUTTER ment. They appreciate keenly such exclusive constructional features as the Patented Tilting Tables, Auto- matically-oiled Bronze Bearings, Heavy U-Shaped Lathe Bed, Circu- lar Saw Raising Lever in the Handi- Shop—the new Welded Steel Stands, Graduated Fence, Practical Rip Gauge, Graduated Miter Gauge, and the convenient arrange- a iin ment, in the new Delta Jointer and Comblastion 4-inch Jointer and Circular Saw Units, which can be 8-inch Circular Saw Unit used with your motor, if desired. ]| Cuts Over 50 Moulding Shapes mounted conveniently on welded steel stand. Both ma- With Only 4 Scts of Blades chin b i together or separately. Furnished with or without motor. alia’ 10 XY a Tri al High speed blades fone pl oa cuts per minute at 3500 R.P.M. des 8-inch Circular y require no individual adjustment. Quick- \ Saw Unit ly and easily locked in position. Spe- mounted separately on Easy Terms cial guide fence. Unusually low price. C sturdy, welded steel stand. Furnished with or without For complete details and full description & & & & & C & of the new 1930 Delta line, send coupon ro S for FREE illustrated literature. Shows ae e& & ie many items of interest to those who work ns | with wood. You will learn, also, how you can try any Delta equipment for 10 days | { i f | ; z under actual working conditions at our DELTA SPECIALTY COMPANY, Dept. B-129 i i i Division of ‘“‘Deita Manufacturing Co.” — —" of three aoayi payment 1661-67 Holton St., Milwaukee, Wis. Plans. Mail coupon Please send me FREE, illustrated literature describing 1930 model ‘Del Woodworki Units. Also details of 10 Day Trial Offer an e Easy Payment Plans. 4-inch Jointer Division of Se CERRO RCT St eR liner , Unit DELTA MANUFACTURING Co, p Eee! | OA of ne tical d n. teen, eee Se 1661-67 Holton St. Ee en RMS tS with or without motor. DEPT, 8-129 A as co ENR ee @ This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approvai of the INSTITUTE OF STANDARDS. See page 8.

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your plant ? Let “Red Streak’? Hack Saws prove they out-perform any blade you’ve ever used. Warn you have a metal cutting job, you want it done as quickly and as easily as possible «++ you want the easiest and fastest cutting hack saw on the market. You want “Red Streak” Hack Saw Blades! Mechanics in all types of trades praise the improved cutting qualities in “Red Streak” Blades. Electric furnace steel makes “Red Streaks” wear-resisting. Evenly set teeth make the cut go straight. They’re made for those who handle a hack saw roughly. Test the “Red Streak” in your hack saw frame and you'll be a booster, too. Look for the blade with the red end. SIMONDS SAW AND STEEL COMPANY FITCHBURG, MASS. “The Saw Makers” Established 1832 Branch Offices and Service Shops in Principal Cities POPULAR SCIENCE prevent the door from swing- ing in too far. A small wood button is screwed to the out- side of the frame to keep the door closed when the screen is folded for storage. A small knob is also added to the outside of the door. WINDO The three: sections are hinged together with dou- MONTHLY DECEMBER, 1929 = i Re enor fee 5 WwINDow T per ble-acting screen hinges to allow for the proper open- ing and folding of the screen. The effects possible through decoration are un- limited. The screen can be painted to harmonize with any desired color scheme. The door frame and the window frames can be painted in a darker color to give a_ realistic effect. Another possibility is to fee ayes 4-0 FRONT VIEW 2i' paint bricks, shingles, or | weather boarding on the walls. Small flower boxes for the outside of the win- dows and cretonne curtains on the inside of the windows give a pleasing effect. The colors of the paint, cretonne, and other decorations are necessarily left to Embossed Leather Billfold Tin attractively embossed _billfold illustrated could well be included in any list of Christmas gifts. It ac- commodates both the new and the old size bills and can be made by the easy and effective method of embossing pre- viously described (P. S. M., Nov. ’29, p. 102). The 4 by 8 in. piece of leather for the re ae STOCK I"*2- Assembly of the play screen showing front plan of door and windows and scenerylike construction of the back members. pam 12-0" ——»| REAR V/LW the individual taste of the builder of the screen. With a little thought and plan- ning a realistic and attractive effect can be obtained. front or outside of the billfold should be tooling calf, which can be bought at any large leather store. If tooling calf is not available, any of the better grade leathers to be found in the ordinary shoemaker’s shop will serve the purpose. In addition to the leather for the front piece, one piece of thinner stock, 8 by 9 in., will be needed. This may be of any comme leather of ordinary thick- ness, lining calf or kid being the best suited. The color of this piece should match fairly well the outside of the fold. Patterns are cut from paper to the shape and size of éach piece, as shown in the drawing at the left. Leather then can be cut to The design of the linoleum die; the arrangement of the die, pads, and blocks; the finished fold and the method of assembling it. the patterns and fitted to be sure that they are cor- rect in size. Piece No. 1 should be large enough to take care of shrinkage when the leather is wetted for the embossing process. Several of ‘the edges, as shown in the sketch, shou!d be skived or thinned with a knife as indicated in the cross section on page 102. The seams that hold the inside pieces in place can be sewed on a sewing machine. The embossed design may be as simple or as complex as you wish. The design shown is of the modern type and is very simple, and it can be made still simpler by omitting the diagonals. A piece of battleship lino- @ This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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101 POPULAR SCIENCE MONTHLY DeEcEMBER, 1929 m) ‘Hello boys uid this, now Jr Air Liner ¥ ELLO BOYS! The boy H whogetsmy new TRALL guullliilllie SQ BLAZING No. 8 EREC- TOR for Christmas will sure be the talk of the town. When you've built your 5-foot model of a real trans-atlantic Zep- pelin, your pals will flock from miles around to look it over— with its giant silver bag, gon- dolas, propellers, landing mast. And that’s not all. I have worked all year to put into these new 1929 Erectors the thrills of a lifetime. You can build almost every mechanical invention you can imagine. Think what a thrill you'll get building these wonderful models that whiz and hum along when operated with your big powerful Erector electric motor. Everything necessary zing No. 8 .. .$25.00 The Set That Builds the Zeppelin. The giant ship of the skies, and hundreds of other great inventions. Includes girders for Zeppelin frame and landing. set. silver bag, gondolas propellers, stabilizers, and in addition includes all the parts of the Sensational No. 7% Erector. , ¢ Sensational No. 71/ Mg%ere¢ Builds the Chassis $15.00 Erector Here’s the set I know will give you the greatest thrill you ever had. Fun? Oh, Boy! It’s the real thing and there’s a thrill packed in every one of its unrivaled parts. Boys, this is one great outfit, and there are hours of real sport waiting for you building auto- motive models. From this great assortment of distinctive, unsurpassable, patented feature ERECTOR parts you can build over 800 models. Automobile Chassis, Tractors, lies beneath the cover of the brass bound chest that holds the new 1929 Erector. With its many new exclusive and pat- ented parts, you can build one after another, over one thousand working models, including Air- planes, Automobiles, Trains, Steam Shovels, Locomotives, Derricks, Bridges, Power Plants; models of every descrip- tion and kind. Now, boys, here’s the way to get this barrelful of red blooded fun. Send for the amazing Mysterious Erectorscope and Catalogue that tell all about Erector. Show it to your Dad—then take him to any good toy store. Let him see Erector himself—watch him warm up toit. He will want to build ieee with it himself. It’s a sure way to get the World’s Greatest Toy for Christmas. AG SUNDAY AFTERNOONS Tune in on RADIO’S ZIPPIEST FEATURE A. C, Gilbert’s Famous Sports Talks Let me introduce to you Babe Ruth, Tad Jones, and other great Sports Heroes of 1929! Hear them broadcast their inspiring messages to the boys of America. Every Sunday afternoon beginning November 10th. Remember the Time— 5:30, Eastern Time — 4:30, Central Time---3:30, Mountain Time—2:30, Pacific Time. Cut out the list of stations below and choose the one you get best on your radio receiver. WEAF... . New York WEEIL.... Boston WJAR.. . . Providence WTAG. .. Worcester WCSH... Portland, Me. WFI... . : Philadelphia t.... Pittsburgh . Washington, D. C. Why the New 1929 ERECTOR is the worlds greatest toy 1 Patented Erector Girder. A real genuine girder like engineers use. The interlocking edge, a novel, exclusive RECTOR feature, eliminates bending and makes it possible to connect two eon, sturdy and strong, with a single olt and nut, and a four piece square girder with two screws only. (In all Erector Sets.) 2 Patented Erector Motors. Power- ful Battery Motor in No. 4, 6, 7, 7% and 8. Famous Polar Cub 110-volt Universal Motor in No. 9 and 10. 3 Patented Assembled Gear Box. Adaptable to every possible gear combination, and for reversing move- ments. Convertible into 3-drum hoist- ing engine. Standardized for use with either battery or 110-volt Motor. In- cluded assembled in the Famous No. 4 Set and up. 4 Heavy Steel Truck Body, 15 inches long. Exclusive ERECTOR feature. In No. 7% Set and up. 5 3%-Inch Solid Steel Disc Wheels with Balloon Tires. An exclusive ERECTOR feature. In No. 7% and up. 6 Patented Big Giant Channel Girders, straight and curved. Elec- trically baked in brilliant red. Exclusive ERECTOR feature. In No. 7 and up. 7 Large Steel Model Building Tray, pierced with ERECTOR standard holes. Patent pending. Exclusive ERECTOR feature. In No. 6 and up. New Erector Zeppelin Features Patented Erector Zeppelin girder, box, big red Other Exclusive Sensational Features Patented curved cheng (in all sets); giant fly wheel machine frame (making possible the building of machinery models); Patented duplex base plate (double standard holes, making it pos- sible to use axles of two sizes); Erector Dredge Bucket, Tip Bucket. Exclusive Mechanical Wonder Features Duplex Plate, Cam, Flat and Cone Pulleys, +, oe and Internal Gears, Eccentric Loop, ete. Exclusive Erector Airplane Features Fusilage, wings, cylinders, propellers, stabilizers, rudder, pontoons, struts, nose, swivel. Sensational Automotive Features Truck body, fenders, radiator, hood, axles, steering wheel and_ knuckle, springs, bumper, heavy duty disc wheels, etc. A Few of the many other Count- less Features Steam Boiler, Steam Shovel, Boiler Plate, Bull Ring, Segment Plate, Per- forated Strips—four holes to the inch (in ,all sets); Erector Gears—Pinion, Crown, Flat, Mitre, Helical, Internal, Quarter, Worm. The only construction toy for duplicating every engineering feat. Possible with no other toy but the NEW ERECTOR. Made from struc- tural steel, plated, brilliantly enameled in colors and electrically baked. Per- fectly interchangeable owing to the minute details of standardization. Con- tains an unrivaled assortment of parts and builds more models than any other Scooters, Fire Engines, and a Hook and Ladder are only a very few. Packed in a big, red steel truck body, famous steel model building tray, manual, powerful electric motor, completely assembled steel disc wheels with oversize balloon tires, fenders, radiator, hood, bumper, springs, steering wheel, heavy truck axles, cab top, steam boiler, steam shovel—in fact, 25 lbs. of scientific thrills for every day of the year. , brass-bound chest, has big 15-inch 88-page, ! BSoeaoon0o00n og yi -O° @ © OG x & } ' :Q0 .OO Famous ERECTOR Sets The New Big No. 7....... $10.00 The Set that Builds the Steam hovel. The Wonderful No. 6....... $7.50 In the Big Red Chest with the Steam Boiler. The Famous No. 4.......... $5.00 With Powerful Electric Motor and Gear Box. Dandy Beginner’s Set No. 1..$1.00 The Set that Builds the Square Girder. The Advanced No. 3........ $2.50 The Set with the Long Girders. The Giant No. 9........... $35.00 The Mechanical Wonder Set, with 110-volt Motor. The Deluxe Set No. 10......$50.00 Complete, Unsurpassable, EREC- TOR in all its glory. Erector Electrical Set, No. 3005.. . chs 6.0.0.6 o.050-0ala eee ea $5.00 The Set that Electrifies and II- luminates. The Big Girder Set No. B.. .$9.50 The Set that Builds the Ferris Wheel. Erector Airplane Set No. C..$10.00 Flies by an Electric Motor. Also Manufacturers of WGY.. . . Schenectady silver bag, gondolas, propellers, stabil- (GR... . Buffalo izers, rudders, etc. construction toy. BIG BOY TOOL CHESTS WSAI... . . Cincinnati , KYW - -: Chieago ~~ er ore GILBERT CHEMISTRY y -+...Detroit s long as they las bs WCCO... -Minneapo FREE! “4. c’étisrrrs Ra erage WCCO... Minneapolis & St. Paul ° , . a ees name ce ee eee ne ee er Lo ae Davenport 7 wee. - - Des Moines AMAZING AND MYSTERIOUS THE A. C. GILBERT CO. 1 4 AE ; ERECTORSCOPE 124 Erector Square, New Haven, Conn. j Wan: . - Milwaukee —— I Please send me re! free copy of the Mysterious i oa Duluth —- The first lucky 100,000 boys will get absolutely Erectorscope and Gilbert Toy Catalog. P BOA seeee ng Cay free the Mysterious Erectorscope. It will fool the IES: icc... 5. COR Ee a 0s bn ea a KGO.... San Francisco smartest boy. You have never seen anything like it. Street t KOMO. . . Seattle Just look through the Erectorscope; you will not | \\ SS=ZenmtmOl 000 0 uuueuusuuccussess t ee Los Angeles n é ‘ity KGW... . Portland, Ore. believe your eyes. Everybody will want to look BOCitY. eee eee cece teen teen een e eens g seapeopee ae through it. Mail the coupon today and get your s > ! enh ashes th, ©. chain : 2 ! ) PRs 6s sn sina pcesesssnse meena 5 Radio Stations Erectorseope and Gilbert Toy Catalog - I san ene tien sites nih. ih cited cin scien ams anata ia dine

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the stays if desired, and the holes unched with ease before the Plastic ood hardens, without danger of chipping or splitting. Sealing Bulwarks Use Plastic Wood to build up, inside or out- side, when the _ bul- warks do not quite fill the rabbet.

Mast-Head Caps are easily made and securely fastened with Plastic Wood. Sand them smooth after hardening. Figureheads Much ingenuity can be shown byshaping Plas- | tic Wood to intricate figureheads. After hardening it can be fur- ther worked with tools without chipping or splitting.

If Plastic Wood hardens too rapidly while working, or for thinning it, or clean- ing hands and tools, use Plastic Wood Solvent. In 25 and 50-cent cans. Hand Hardens like into Putty Wood 1 Ib. can % |b. can $1.00 35 cts.

At Hardware and Paint Stores ADDISON-LESLIE COMPANY 322 Bolivar Street Canton, Mass.

leather punch through all of the thicknesses of leather at once. The lacing is usually kangaroo or wallaby skin cut as shown, but any thin leather will serve the pur- pose; even the leather salvaged from an old pair of shoes or slippers may be used. The correct width of the lace is about %@ in., and should be cut to a length _ of about six times the combined distance around the billfold. To flatten out the | lacing, the laced fold should be hammered

along the edges, and then shellacked to make it stiff. If a colored effect is desired, the color may be applied over the pebbled surface, wiping lightly until the desired tone is Sharp Knife Aids in Model Plane Building HE most important tool in model airplane building is a sharp knife. Some model builders prefer using-a safety razor blade, feeling that it is sharper and therefore more efficient and quick cutting. This is very true, but it also presents the ever-present danger of a badly cut finger. A knife is much to

Patterns of various pieces that go to y i i THE STITCH HERE / make up finished billfold, method of SnGan Bre nest J lacing, and how skiving is done. TO USE FOR THE y/

102 POPULAR SCIENCE MONTHLY DECEMBER, 1929 4 —__—— _ FE M l Bo leum, exactly thesize of the ci s LINE OF LACING or Mode ats | | billfold, is used for the die. ae spots eis? The design is laid out on the ae ) 1 2 \ NEW SIZED BILLS | Be eT es ae face and carved in very low SEW ie 2 ae , + t relief. If the carving is done HERE \ _ . dows | — BP roetnecinees | with a penknife, the back- ial i ' ; ya ground should be gouged | m | out in chunks, leaving the oe ' = @. al carving rough and pebbly. .s ls | “x =f Some wet paper impres- —|-'%e = 1 ae sions should be made first oe | : = @ to make sure that the result (V = 3) is just what is desired. The —I—- e = = leather is then thoroughly b—'4 . I wetted and pressed into P the die by using a vise or TOOLING CALF 4"x6"FOR press, as shown. it... ae _ When the embossed sec- Me a tion has dried thoroughly, scons. 44, WIDE = ¢ and the various edges have <xiyep mi al been skived, sewed, and fit- £0GE oar or Tene u LF WITH THIN ted where necessary, the EDGE GLUED TO NO.2 | parts are cemented in place secrion a 3%4x8" with ordinary rubber ce- AA COMPARTMENT FOR LARGE BILLS : : 0. ; ment Care should be taken a COMPARTMENT FOR NEW ae . : PLASTIC WOOD | | cusiiiiesnent SE BE | is placed only on the edges. ee OTT AS TT es TT (Reg, U. 8. Pat. Of] | The billfold is now ready b%x2%|2% x3" Fer Mashing Blocks | to be laced. The holes for 28 O nen spees } mi ‘ | the lace are punched with —eme LESS BULKY (™, 8x9; ALSO Blocks and Deadeyes can be readily an ordinary nail set or a ae moulded with the fingers, right into 1%4x2% 2 OW SKIVING 1S DONE SRESISESISS BILLFOLOD

obtained. Any oil or flat artists’ color may be used, if thinned down with gaso- line or benzene. The whole billfold when completed is carefully waxed with a good grade of ordinary floor wax or shoe polish in order to provide a smooth, finished-looking surface.—F. CLARKE HUGHES. This is the second of a series of ar- ticles by Mr. Hughes dealing with ap- plications of this new, easy, and effi- cient method of embossing leather. When the blade is free from nicks, it should be whetted on the smooth side of the stone until it begins to stick as you rotate it. The blade is now ready for stropping. Place the blade flat on a leather strop, the cutting edge toward you. Stroke the blade away from

be preferred, and if sharpened fre- quently in the man- ner to be described, it will perform every cutting job quickly and accurately. In sharpening a knife, hold the stone in the palm of your hand, put a few drops of oil on it, and place the knife blade, cutting edge flat, on the surface. With a gentle rotary motion, rub the blade on the stone. hYVER handle plane.

Toy Plane with Controls | Well, if you happen to be a | . boy—particularly a boy whose father likes to help you build things—you will be able to do it next month. An article will be published in the Janua issue of POPULAR MONTHLY telling how to con- struct a good-sized toy airplane cockpit where you can sit and work controls just as in a real And a model mounted in front will bank and turn in response to every movement of your joy stick and rudder bar. you and at the end of the stroke give the blade a _ half turn and draw it back toward you. Just turn the wrist until the edge of the blade points oppo- site to the direction of stropping. Three or four minutes of rapid stropping will be ample. Try the blade by seeing if it will slice paper without tearing it. —A.W. JACKSON. a joy stick? ry, 1930, SCIENCE

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—————— DecEMBER, 1929 POPULAR SCIENCE MONTHLY 103 NATION-WIDE CONTEST TO ENCOURAGE APPRECIATION AND PERFORMANCE OF MUSIC BY THE YOUTH OF AMERICA [mee Eminent musicians and educators, civic authorities and leaders of public opinion have been so eulogistic in their praise of the harmonica as a means of foster- ing in the youth of America a proper appreciation of things musical, that a nation-wide contest has been inaugurated to intensify the already keen interest of American youth in this universal musical instrument. ERE is your opportunity to win a valuable prizeand tohave plenty of fun while doingit. This is a contest for every boy and girl—and there aremorethan five hundred fine prizes to be awarded. Regardless of how old you are, or in what grade at school you are, you all have an equal chance to win one of the prizes. The judges will take all this into consideration when mak- ing their decision. Hohner “MARINE BAND” the ideal instrument for the beginner, embodying almost two octaves in the diatonic scale. . . - «+ Price 50c Hohner “AUTO VALVE”. Ten double holes. Wind-sav- ing device permits greater volume of tone with no more effort . . Price $1.00 The contest is for the best compositions on the subject: ‘‘My Experience with the Harmonica.” It is easy to enter this contest. Every boy and girl under eighteen years is eligible. You don’t even have to buy a harmonica to enter this con- test. You don’t even have to owna harmonica. Even if you have never tried to play a harmonica in all your life, you can compete for a prize. If you desire to purchase any of the dels sh bove, and c t obtain them from gour dealer, we shall be glad to fill your order by: mail, postage paid, on receipt of money order for the price. HOHNER Hohner ‘““CHROMONICA”. Supplies all half-tones by the slight shifting of a lever. Any selection, in any key, can Played onit . . Price $2.75 Harmonicas pa die BOYS and GIRLS 71000 in PRIZES — Simply use the coupon in the corner below to ask for a Hohner Instruction Book so you can quickly learn to play a tune on the har- monica. The Hohner Instruction Book will give you a head start on the boys and girls who neglect to get one. Along with the instruction book, you will teceive an entry blank and a harmonica catalog illustrating almost fifty models of the famous Hohner harmonicas. The entry blank will tell you just what to do, and how to proceed in competing for the more than five hundred prizes which will be given away. FREE How to Enter the Contest TO EVERY ENTRANT Remember, whether you enter the contest or not, the Hohner Instruc- tion Book will be a big help to you. Even if you don’t succeed in winning a prize, the ability to play areal musical instrument will be its own reward. Playing a harmonica will ode so much to your per- sonality and popularity to your happiness and cultural development that you'll always begla you learned to play one. Contest Editor, Dept.so04-M, M. HOHNER, Inc., 114 E. 16th Street New York City, N. Y. Please send me FREE items checked below: Instruction Book [J Catalog (] Entry Blank (] Name ee! Address £23

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104 : Christmas Git brings You Popularity HOUSANDS will start toward mu- sical success on Conns this Christmas. The one gift that brings you fun ..- popularity and end- less chances to make extra money. Join a band or orchestra. It’s easy. Anyone who can whistle a tune can learn quickly. Easy to Play Saxophone, Cornet, Clarinet, Trumpet, Trom- bone—any band or orchestra instrument you choose. Conn makes them all. And Conns are easiest of all to play. Choice of Sousa and the world’s greatest artists. Especially recommended to beginners for quick progress. Easiest to blow, Easiest to finger. Easiest to play in perfect tune. The result of more than 50 years’ experience and patented processes of manufacture exclu- sive with Conn — the world’s largest maker. Yet a genuine Conn costs you no more than any so called standard make. FREE TRIAL, Easy Payments Any Conn instrument sent for free trial in your own home. Easy payments if you wish. Write for FREE BOOK Write now for interesting booklet illustra- ting latest models in colors. Tells everything you want to know about your favorite instru- ment. Mention instrument. Cc. G. CONN, Ltd., 1232 Conn Bldg. Elkhart, Indiana ININ WORLD'S LARGEST MANUFACTURERS of BAND INSTRUMENTS = we ee oe eh OR a Sy St a en a me C.G.Conn, d., 1232 Conn Bidg., Elkhart,Ind. §f j Gentlemen; Send free literature and details of trial JJ B offer on_ (Instrument) ¥ i Name i 8 SscorR.F.D 7 B City. i B scate, County. ; EMAIL THIS COUPON. POPULAR SCIENCE MONTHLY DECEMBER, 1929 HE miniature mo- tor-driven workshop machines shown, consisting of a lathe, drill press, sander-jointer, and circular saw, not only serve as educational toys for children having a me- chanical turn of mind, but will actually turn out work that is accurate enough for model parts and small toys. The cost of building these ma- chines is negligible; for instance, the lathe cost the writer a little over a dollar to complete. For those who wish larger drawings and more complete details, a blueprint has been prepared to show the actual construction of each part as well as the assembly of all four machines. This blue- print can be obtained by sending twenty- five cents to PopULAR SCIENCE MonruHLy, 381 Fourth Avenue, New York, N. Y., with a request for Blueprint No. 113 (see page 110). The lathe has an over-all length of 14 in., but the builder can increase it up to 24 in. successfully, if desired. The spindle | is held in bronze bearings, which are split | to facilitate tightening when they become loose. A model-T Ford front axle steering spindle body bolt was used for the spindle. As the bolt is 4 in. in diameter; it allows the use of standard chucks and faceplates such as are sold by many of the manu- facturers of portable type woodworking machines. In preparing the bolt, remove the bolt- RR PRE KN SSING = two coats of shel- Toy Woodworking Machines By M. CYLE SMOCK, Jr. Aside from being a toy reproduction of a lathe, this small machine can be used in making ship model dead- eyes, capstans, and the like. een, head just below the oil groove and smooth up the cut with a file. The straps that hold the spindle bushings in place can be made from %-in. sheet brass or strap iron. In a small lathe of this type there is very little thrust, therefore a small brass washer placed between the pulley and the end bearing block will serve the purpose of a thrust bearing. In setting up the spindle, great care should be taken to see that the bearings are in line and that the spindle is allowed to turn easily. The dead center is of the lever con- trolled variety (shown in the illustration at the top of this page). The lever is made from a % by % by 8 in. strap-iron piece, and is held in place with 3¢-in. stove bolts, cut off at the right length and riveted over. The tailstock, which has a slide bolt for locking the stock at any position on the ways, is made from five pieces of wood: the two main pieces, the clamp for holding down the spindle bushing, and the two spacing blocks. Finish the wooden parts of the lathe with lac and then en- amel to suit. The base and brackets of the drill press are cut from %-in. wood while the frame is made of %-in. stock. The table, which is supported by The miniature drill press. The chuck, taken from a hand drill of the spiral type, is pinned and soldered to the spindle. a spool, is cut from %-in. stock to a diameter of

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I —— DeEcEMBER, 1929 POPULAR SCIENCE MONTHLY 105 HERE’S A LIONEL ELECTRIC RAILROAD THAT ANY BOY CAN BUILD es wet 5. oy Sai MS tse ope Fy ON THE RADIO Starting Nov. 8th Every Friday night. 6:30 to 7:00 Eastern Standard Time, * Uncle Don" and his Lionel Engineers’ Club orer stations WOR, WLW and WBBM UListen-in and en- joy this wonderful Lionel radio powre™. and laugh with ** Uncle n. _ photographs tell the whole story better than a thousand words. They show you how Lionel Model Electric Trains look in action! They picture the realism of these remarkable locomo- tives and cars. They show you what you can do with your Lionel trains and accessories this Christmas. With such a Lionel Electric Rail- road you learn many of the details of actual railroading, for Lionel Railroad Systems are true-to-life models of the big railroads of the country. See the new Lionel Steam Type Luco—electrically driven by the fa- mous Lionel “Bild-A-Loco” motor— Lionel Electric Trains are priced from $7.00 to $325.00. FREE BOOK FREE: Don't delay another in- slant, Write today for a FREE copy of the new Lionel 46 page handsomely illustrated Railroad Planning Book and catalog, and pick out the sel you want for Christmas. themotor that may be removed ina jiffy, taken apart and reassembled again. Also, see the new Lionel electric type locos. These “Giants of the Rails” are the most powerful model electric locos ever built. Remember, to, that Lionel trains can be controlled and operated by LIONEL ELECTRIC TRAINS MODEL RAILROAD ACCESSORIES @ “MULTIVOLT” TRANSFORMERS Lionel “Distant-Contro]”— which en- ables you to start, stop, reverse or switch your trains at any distance from the track. Write for the catalog today—it shows all the new Lionel models. See the Lionel demonstrations at your local stores. The Lionel Co ration, Dept. D 15-17-19 East ‘Street, New York City THE LIONEL CORPORATION, Dept.D, 15-17-19 East 26th Street, New York City

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106 ever before —~ such STRENGTH in a screw driver!

Prying opena head with the Bridge.

Guaranteed! 1 You can't twist * the handle—the hexagonal head and heavy steel rivet pre- vent turning. 2 You can hammer * the head — its broad stee! surface takes the blows. 3 You can pry with * it—its one-piece heat - treated blade withstands _tremen- dous leverage. POPULAR SCIENCE MONTHLY DEcEMBER, 1929

| is a disk of sheet tin, 134

4 You can chisel * with it im an emergency—its dual tempered and twice- tested poirt won't mushroom.

— we could make the Bridgeport Red Crown one jota stronger, we would—but we can't! Skilled workmen tell us they have never seen a screw driver so powerfully built. Look at the transparent view, above. Read about the remarkable combination of features—found in no other screw driver. Then you will know why expert mechanics prefer the Bridgeport Red Crown. And you will know why you should own this extraordinary tool! Ask your dealer today to show you the Bridgeport Red Crown—identified by the bright red crown atop the handle. If he can't supply you, order direct—sof¢. THE BRIDGEPORT HARDWARE MBG. CORP. Bridgeport, Connecticut, U.S. A. The World's Largest Makers of Screw Drivers Bridgeport TRaceE

THE CHOICE of MEN WHO KNOW TOOLS | inner end.

2% in. The two arms are made from ¥-in. strap iron and are bolted to the top of the frame as shown. Iron washers are put between the pulleys and arms to serve as bearings. On the inner sides of the spool pulleys in. in diameter, which serves to keep the belt from run- ning off of the pulley. The shafts, on which the pulleys run free are made from %¢-in. nails cut to the right length and slipped through holes in the arms. The spindle is a %4-in. rod 41% in. long. Its bearing is made by first boring a 14-in. hole in the arm (spool) and afterwards greasing the spindle and centering it in the hole. Melt some babbitt in a ladle and pour it in around the spindle. In this way the bearing is formed right in place and around the spindle. The chuck was taken from a small drill of the hand variety that can be bought in many five-and-ten-cent stores. It is soldered and pinned to the end of the spindle. A coil spring is slipped on the chuck spindle, as shown, and serves to keep the chuck raised when no

The drum sander is designed to simulate an actual jointer of the commercial motor-driven bench type.

In this way the blade will cut its own slot and thus will be assured of an accurate fit. No ripping fence or miter guide is shown because a piece of wood clamped to the table top with C-clamps serves the purpose. The drum sander is so constructed as to represent an actual bench jointer. The frame is cut from %-in. stock while the centerpieces are made from %-in. Cut the slot in the table by sawing from the back at an angle of forty-five de- grees. A mold for the bearing is made from wood, and the metal melted and poured. After the bearing is cold, saw the bar in half and drill for the spindle. Fasten the bearing in place with 3¢-in. countersunk machine screws. The spindle is made from 14-in. rod and is 35% in. long. The sander drum is 1 in. long and 1% in. in diameter and has a %&-in. hole for the pin which is made from a nail. The sandpaper is cut in convenient strips 1 in. wide and is glued on the

pressure is applied to ---CLEATS~~_ drum. the knob on the top of ry a Y, The proper height for | the spindle. oe AWC “J the sander drum to pro- | The circular saw uses a | 241. Tt ject above the table top | small, thin 2'4-in. diam- if [- 4 at = can befound by a process | eter metal saw, since ,|| } 41 (ae yt | |, of trial. | | woodworking saws are * es ; ¢ The belts can be made | not ordinarily made in +=) “L gittiage ! by using the leather ob- such a small size. = we tained from a man’s The bearing for the | ee oe ee leather belt of the cheap saw spindle is molded < Bis: ‘J variety. The only specifi- | of Babbitt metal in a ) it cation is that the leather | wooden mold cut to the TABLE mi BABBITT be soft and flexible. | size and shape desired. | BEARI If any of the belts With . py es — e | tend to slip, — — | saw, slot the front ha ; * of tape on the pulleys | of the bearing; this will HINGE - : | will Rae to remedy the offer a means of taking _f77Z7z7?"------ ? zy ~©trouble. up the bearing wear. TTI1L © a 7 The machines can be | The spindle is a 4% by x, \ Cun 2, far *@ painted with a silver- | 4% in. long steel rod, |. %, LZ) ‘~ bronze paint for the table threaded for a distance Meat | tops and a gray enamel paint for the frames.

of about 34 in. on the The saw is held in SIDE ELEVATION (TABLE IN SECTION ON LINE AA)

place by putting a right- handed nut on the spin- ~ dle, then the saw and The babbitt bear- ing is cast in one piece in a wooden mold and is split. another right-handed nut. This will hold the saw firmly in place and will allow any adjustments that may be necessary. The table top is hinged to the frame with a 1 by 1% in. hinge. After the frame and top have been made, the bearing put in place, and the belt to the countershaft connected, raise the table and attach the saw blade. Start the motor and lower the table on the saw.

As small circular wood saws are practically unob- tainable, a 2'4-in. diameter metal saw is used.

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

Page 109

DECEMBER, 1929 or. . ‘ Semiautomatic Box | Serves Cigarettes One by One

One of the cigarette boxes finished in green crackle lacquer over a black undercoat color. an attractive cigarette box for the end table or smoking cabinet, which may be made easily in the home work- | shop. The only tools required are a saw, a plane, and a chisel. For the school-shop with such equip- ment as the dado saw and jointer—and when there is no objection to having the boys make smoking equipment for gift purposes or for sale—the making of a number of these hoxes forms an instruc- tive exercise in mass production. It should be noted that the top of the | box is glued in place. The cigarettes are inserted from the bottom. For that reason the spring stop is set in a recess so that it can be depressed sufficiently to | allow the removal of the slide when it is | necessary to refill the box. The boxes may be painted, finished natural, or lacquered. —H. R. Goppert and E. SPRAGUE. T=. accompanying illustration shows

SPRING STOP // Va" V2

SECTION A-A

POPULAR SCIENCE MONTHLY To and Fro Turnr ight ee a = thenleft drives the screw ADD this pair of ‘‘ Yankee” Ratchet Screwdrivers to your kit. Ingenious tools .. . efficient . . . interesting to use! You grasp handle just once and simply turn it to and fro. The “Yankee”’ Ratchet drives the screw. Saves your strength and time. Smooth asstem-wind on your watch. No Tiny screw friction—no turning started by turning screw back. One ade wit . thumb and hand does the job. forefinger. And not a moment or motion lost. Where many screws are driven, the ‘“*Yankee” Ratchet saves a fourth to half of man’s time.

No. 15.—Takes care of pes- ky little screws. “’Thumb- turn” on blade starts the wobbly screw. Ratchet movement drives it home. Blade, ;;"" diameter. Six lengths: 2”, 70c; 3, 75c; 4”, 8oc; 5”, 85c; 6”, goc; 8”, 95¢. No. 10.—For hus- ky screws. Eight blade lengths: 2”, 65c; 3’’, 80c; 4”, 85c; 5”, 95¢; 6”, $1.05; 8", $1.20; 10’, $1.45; 12’, $1.60. Ratchet Shifter moves length- wise. No. 11.—Same as No. 10,except Ratch- |j et Shifter moves spt across tool. All have }‘,*, <— right and left ratchet Places to be able toratch- and rigid adjust- et the screw ome wit ments, one hand.

©

107

“Tx NKE K”’ ‘‘That’s the best there is!’’ says the man who sells tools.

oe were es oe ee’ YANKEE” TOOL BOOK COUPON ae wre: oe ree oe oo oe Nortu Bros. Mrc. Co., Purrape.puia, U. S. A. Send ‘Yankee’ Tool Book, showi Quick-Return Spiral Screw-drivers, Automatic Push Drills, Ratchet Hand, Breast and Chain Drills, Automatic Bench Drills, Ratchet Braces, Bit Extensions, Push Braces, Ratchet Tap Wrenches, Removable-base Vises, etc.

SLIDING DELIVERY 1 RECESS “6 DEEP DRAWER UNDERSIDE OF SLIDE Principal parts of the case, a cross section, and a sketch as it appears when assembled.

H | nN NT Meerr Tm ee erm ts BEN en

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

Page 110

A ETS ees aD 108 POPULAR SCIENCE MONTHLY DecemMBEr, 1929 A $100 SHIP MODEL for $4.98 SANTA MARIA 25” High; 11” Wide; 27” Long You can put a beautiful Ship Model together in a few hours of pleasant pastime Let the World’s Largest Builders of Ship Models supply you with all the necessary parts cut to fit and ready to ut pean as for the models, Santa aria, Mayflower, or La Pinta. You need not know anything about — building to assemble one of these m els. If you have never seen a ship model you can put one of these models together in a few hours by following our diagram and instruction sheets which explain and show you exactly what to do with each part. All you need i is a small tack hammer to tap the parts in place. The diagram makes it impossible for you to go wrong. These models when com- — are —= in every detail of the amous old ships they represent, and when Aa will add a distinctive touch to your home. We also have parts for the models for the Constitution and Flying Cloud at $6.98; all other models listed at $4.98 each. Mayflower; Size: 26” high, 10” wide, 498 These prices are f. 0. b., Philadelphia, plus a few cents postage. Write for our beautiful illustrated booklet con- os photos and information on all of our models. MINIATURE SHIP MODELS, Inc. Dept. N. A., 3216 Baring Street PHILADELPHIA, Pa. Miniature Ship Models, Inc., Dept. N. A. 3216 Baring Street, Philadelphia, Pa. Please send me the complete parts cut to fit and ready to put together for the Model............. I will pay postman..... postage Agua print name and address plainly to avoid de- lay. Name + diab dps oie eed 60 bedeede Rs 46 60% City. State.... Four Useful Everyday Knots By ~ Water E. BurToN NE of the most useful members of the knot family is the square or reef knot. It is employed for tying two rope ends together and is perhaps the most satisfactory device for securing the cord on packages. Its many other uses include the tying of bandages, for it can be adjusted to just the right degree of tightness. The square knot (Fig. 1) is essentially the looping of two rope ends about each other. First twist the ends together once, bring them up bending the rope so that they point in directions opposite their first position, and loop one about Fig. 1. The square or reef knot is easily tied, untied, Fig. 2. This invisible-end and will never slip or jam. wrapping is effectively used in mending split chiselhandlesandthelike. the other again. Then draw the knot tight. The only precaution is to see that the end of each sec- tion of rope is on the same side of the loop formed by the other piece as the main, or “standing,” part. If it is not, the result will be the weaker “granny” knot. In tying the square knot, especially in binding packages, it may be Fig. 3. Pulling the end through, thus fastening it and making it invisible. Fig. 4. The knot at the right, if tied on the end of a rope, prevents fray- ing and serves to keep the rope from slipping through a pulley or hole. Figs. 5, 6, 7. The bowline when tied properly forms a loop that will never slip and is easily untied, and because of this is a useful knot for many purposes about the home as well as on board a ship. A piece of rope with a bowline at each end can be used for hanging a coil of garden hose on a hook.

Page 111

DeceMBER, 1929 necessary to hold the cord in place with the finger after the first twisting, until the knot is completed. The knot never slips or jams and is easy to untie. A method of repairing split chisel or knife handles, tennis racket frames, and similar objects, and of forming a non- slipping grip on various handles, is to wrap them with a layer of cord. In doing this, the cord ends can be made invisible and secure by a simple little trick. When starting the winding, arrange the end of the cord so that a loop extends under the winding and a short distance beyond the area that will be covered. Wind the cord over the loop, as shown in Fig. 2. When the required amount has been applied, cut the cord so that a few inches remain, and pass the cut end through the loop. Then pull the starting end until the knot—if it can be called a knot—is beneath the wind- ing (Fig. 3). Trim off the surplus cord. Frequently it is necessary to form a knot at the end of a rope to prevent fray- ing or slipping through a pulley or hole: The method of doing this, which is shown in Fig. 4, consists simply of winding the end about the standing part several times, inserting it through the loop formed, and pulling it taut. The bowline is a knot that appears complicated but really is easy to tie. Its purpose is to form a noose that neither jams nor slips. It is used sometimes for lowering a person “by a rope, as from a burning building. A piece of rope a yard or so long, with a bowline noose at each end, makes an ideal device for hanging the garden hose from a nail or other projec- tion, by first coiling the hose, passing the rope once or twice about it, and slipping the end loops over the support. A rope with a bowline loop is useful in tying a boat to a post. Steps in tying the knot are shown in Figs. 5,6, and 7. First form a small loop in the rope and bring the end around and up through this loop so that a larger one is formed. Pass the end about the main | portion of the rope, bring it back down | through the small loop in the opposite direction, and pull the knot tight. Support for Slender Work ONG shafts, which must be handled between centers for milling machine operations, frequently give trouble by springing down in the center. Sometimes blocks of various shapes are used; at other times there is a steady rest of some sort with the milling machine equipment. In the event that there is nothing to support the shaft, a steady rest, one that is adaptable to a large range of work, can be made from two pieces of flat steel and two bolts. The construction and use of the device are evident from the illus- tration.—H. L. WHEELER. Improvised steady rest used on milling machine. | POPULAR SCIENCE MONTHLY Here’s A Profitable One | i= FIVE FOOT WORK- SHOP INCLUDES: 4” Planer, 8” Circular Saw, 6” x36” Lathe 8” Disc Sander; 6” Buffer, 5” Grinder, 4” Drill Chuck, 4 H.P. G. E. Motor, 110 ¥., A. C., 60 Cycle. End- less V Belt. Two 2-step nd Saw may be pur- sed sepg ‘arately cha _ $25.00 each. * Jig Saw Attach- ment for the i 1s ft, Workace Band Saw, ecobomlical..!..... $75 orkace Radial Saw. awsatany © 1 angle........ ~~ ERE’S A HOBBY that gives you relaxation from everyday cares—bringing pleasure and profit. Thousands of men have adopted the Workace hobby. Make hundreds of things with the Work- ace Electric Woodworker. Under the magic of the whirring saw, planer, lathe, sander, drill, grinder and buff- ing wheel (all are included in the Workace Woodworker) raw lumber is easily converted into furniture, household necessities and countless other articles. Work out your own ideas with your own complete elec- tric workshop. There’s no better gift for the grow- ing boy than Workace. It provides a wholesome man-building outlet for his energy and enthusiasm. Man or boy will appreciate the Workace. $9.00 down will bring it. To operate simply plug into the electric light socket. Send the coupon now for details. J.D.WALLACE & COMPANY Wilcox Street at California Ave., Chicage 11 West 42nd Street, New York City 268 Market Street, San Francisco Consult telephone directory for branch addresses in other cities r} r —_ { J.D. WALLACE & COMPANY Wilcox St. Please send me full information about the Workace Elec- tric Woodworker and also the Workace Machines checked at California Ave., Chicago, Til. below. Workace Workace Jig Saw Band Saw Workace Workace Workace 1 Shaper Planer Radial Saw POG... ciccdattbosspeanmse nbnieins oil. ae ING oo inc ncncdnsccccsntanncseeannsael a PE ee Paetsch © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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110

POPULAR SCIENCE MONTHLY

are no toys. They are thor- low pri oughly tried and practical y : machi ces. be bought Make Your Hobby Pay Dividends “Driver” Power Tools are designed particularly for the home craftsman. Thousands of users—from professional men, lawyers, doctors, clergymen, and en- gineers who make wood- working their hobby, to the school boy who operates his set to earn money,—all are deriving pleasure and profit from the “Driver” Work- @ ~—s up from the same giving full details.

his is what the ‘Driver’ Line offers - you, made as through quantity production and ern manufacturing methods. Price Limit of $1.00 Per Part! _——~y! the motor, every ‘“‘Driver’’ poaciene can Le? not over $1.00 each instance the lathe is sold in four at $1.00. The same holds true with the other tools. Besides, many of the parts are interchangeable so that in some instances meee than one tool can be rt local dealer will cupply you with a circular

Chain Stores: W. T. Grant Co. S. S. Kresge Co. & W. Grand Co. Schulte-United, Inc. McLellan Stores Neisner Brothers 73% Stores . J. Newberry Co. Mail Order: . For rts each retailing

“OZZns eh icago, Illinois an retail stores. department stores and hardware dealers.

+ Not sold direct You can buy the “DRIVER’’ Home Workshop a part at a time—as you need it! Lathe Complete $4.00 Ready to Run Approved by A guaranteed, woodturning power lathe, 30” long “DRIVER” Tools Popular Science % with a 6%” swin ng. complete for $4.00! A jig saw, ® Sold Nationwide Institute bench saw and dado, belt sander, disc and drum Through the Followin sanders, flexible shaft, lishing and grinding head, gn. & “Driver” Power Tools | shafting and pulleys; —all available at corresponding- Retail Outlets: Soa, | Roebuck & Co Ch d Also sold by thousands of Buy from dealers— WALKER-TURNER CO., INC. ol JERSEY CITY, NEW JERSEY

Young Man- Here's Your. Opportunity to MAKE BIG MONEY Start in Business fer Yourself Now! FOLEYexrcSAW FILER Nothing else like it in the world. Files hand, band and circular saws automatically with such mechanical accuracy that they cut faster and stay sharp longer. Better than the most expert hand filing. Easy work to file 5 to 6 saws an hour. No experience necessary—even boys of 14 are operat- ing the Foley. No Canvassing You can get all the business you can handle —— contractors, schools, saw mills, factories every other kind of business. Lots of men are eoline big money filing saws on the Foley. “I have 262 school saws in my shop now besides many others,” says Mr. M. S. Gray. Send for free plan — . ows you how to build a permanent, well cash business of your own. Start in spare = F you wish. Mail the coupon below today. This Plan FREE FOLEY MANUFACTURING CO. 1010 Fol , 11 Main St. N. E. Minneapetis, send me free plan showing how I can make big money and start my own business with the Foley.

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Hunters, Wild and Farm Animals. ls. Easy and inexpensive to A. material. Send 5c Stamp for Illustrated Catalogu Henry C. Schiercke, 1034-72nd St., Brooklyn, N. Y. a SA wt FORMS TO CAST LEAD Sen. neens INDIANS, TRAPPERS, Wonderful ‘‘True to Life’ I 9 sh all necessary

Need ROOT Presents the | ORBIN Hand Re We ACe inR.PM the speed of any revolving shaft. Handiest instrument ‘for checking-up speeds of motors, generators, engines, line Centrifugal principle; powerful, uniform action. Indicating pointer holds steady; gives precise, Unaffected by Price, f.o.b. factory, $30. Full description - shafts, etc. instant readings. temperature or moisture. in new Bulletin; write— R RATE D Noedaii- OOF ener CONN. OFFICES IN PRINCIPAL CITIES: WRITE OR PHONE

DeEcEMBER, 1929

aiiee Blueprints tim (iit Home Workshop |

T° ASSIST you in your home workshop, PopuLaR SciteNcE Monruaty offers large blueprints containing working drawings of a number of well-tested projects. Each subj ject 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 86. 35-in. Twin Pusher 87. 30-in. Seaplane 89-90. Bremen (3-ft. flying), 50c 102. Morris Seaplane (record flight 12 4 min.) Tractor (record flight 6,024 ft.) 104. Furniture * . Sewing Table Smoking Cabinet End Table with Book Trough . Kitchen Cabinet . Tea Wagon Cedar Chest Telephone Table and Stool . Grandfather Clock . Flat Top Desk . Colonial Desk . Gateleg Table . Kitchen Cabinet Table . Two Sewing Cabi- nets . Dining Alcove Rush- Bottom Chair . Simple Bookcase . Sheraton Table . Chest of Drawers . Broom Cabinet . Welsh Dresser 68. Magazine- Rack Table and Book- Trough Table 70-71. Console Radio Cabinet, 50c 77. Simple Pier Cabi- net and Wall Shelves Treasure Chests Modernistic Stand; Modernistic Bookcase - Modern Fold- ing Screens Three Modern Lamps 0. Modernistic Book Ends, Book Shelf, Low Stand . Tavern Table and Colonial Mirror ne 78. 88. Radio Sets One-Tube (battery operated) Three-Stage Am- 103. 42. plifier 43. Four-Tube (battery | operated)

S loNarmsde ak <ul de ale cd cents. Five-Tube (battery operated) . Five-Tube Details . Electric . Electric High Pow- er Unit - Electric Low Pow- er Unit One-Tube Electric 98. Two-Tube Electric 99. Four-Tube Electric 109. Screen-Grid Set Ship Models 44-45. Pirate Galley or elucca, 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’’), 75c 61-62. Viking, 50c 63-64. 29-in. Toy Motor 0c Boat, 74-75-76. Santa Maria (18-in. hull), 75c 83-84-85. Mayflower (1714-in. hull), 75c 92. Baltimore Clipper (8 in. long) 94-95-96. Mississippi Steamboat, 75c 106-107. 42-in. Racing acht, ea Scout, 50c 66.Ship Model Weather Vane 108. Scenic Half-Model of Barque 110-111-112. Schooner Bluenose, 75c Toys 28. Pullman Play Table 29. Tea Cart, Wheel- barrow, and Garage 56. Birds and Animals 67. Lindbergh’s Plane 72. Colonial Doll’s House 73. Doll’s House Furniture 101. Fire Engine, Sprinkler, Truck, Tractor 113. Lathe, Drill Press, Saw, and Jointer Miscellaneous 15. Workbench 26. Baby’s — and Play 30. Tool Se Bor- and 65. Six Simple Puzzles Price 25 cents each except where otherwise noted Name City and State. ............ eee eee eee eee eee ee eee eee — “1

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

Page 113

DeceMBER, 1929 Medel of Darmstadt Type Sail Plane By VINCENT JOHNSTONE Model gliders act very much like real airplanes. ROM building model sail planes much can be learned regarding plane con- struction and the principles of flight. The glider illustrated, which is easily made, is a reproduction of the famous Darmstadt sail plane. Models of this type have flown on the level for sixty feet when launched from a height of a little over seven feet. By variations in the way this sail plane is launched, it can be made to fly straight or loop both vertically and hori- zontally, simulating in many ways the actions of an actual airplane. For making the wing you will need a 3 by 114 by 18 in. piece of balsa wood veneer. Make a pattern of the wing and cut the balsa accordingly. The front edge of the wing, it will be noted, is the edge having the least curvature at the tips. Round both of the tips of the wood so that they are exactly alike. Locate the center of the wing and with a sharp razor cut about halfway through the wing along the center line from front to back. Carefully crack the wing so that both wing tips will be 34 in. higher than the center. Next cut a small piece of balsa 134 in. long by \ in. deep at one end and 4 in. at the other. Place the wing upside down on a flat table or workbench, with the center of the wing supported by a block. With the wing in this position, carefully cement the 134-in. balsa strip across the center of the wing as shown in the sketch on page 112. The small end of this balsa piece, Balsa wood, wire, and cement are the only ma- terials needed in making this model glider. POPULAR SCIENCE MONTHLY Own a Car your friends can admire b dws needn’t envy your friend’s fine car — or be ashamed of your own—when you can buy a fine quality mo- tor car for little money. Many good used cars have their orig- inal beauty, style and distinc- tion, with thousands of unused miles. And you can buy a really fine used car for the price of a cheap new car. By buying your used car under the terms of the famous Studebaker Pledge, you get positive satisfaction-insurance. The Pledge gives you five days driving trial with any used car you select. You get a 30-day guarantee on all Certified cars. And all prices are plainly marked —there are no code prices on a Pledge-backed used car. Pledge to the Public on | Used Car Sales | ar A ay nape foe ome and that price, just as the price of our new cars, is rigidly mae i we 4 All Studebaker automobiles which are sold as CERTIFIED CARS have been properly reconditioned, and carry a cement of Yy guarantee for service on ad- defective parts and free justments. Every purchaser of a used car may 3 drive it for five days, and then, if not fied for any reason, turn it back and apply the money paid as a credit on the purc of any other car in stock—new or is assumed that the car has not been damaged in meantime.) eR © 1927 The Studebaker Corporation of Ameri This free booklet, “How to Judge a Used Car,” will teach you many fine points about used car buying. The Studebaker Pledge will thoroughly protect your motor car investment. Act now to give your family a better car—mail the coupon today! 111 STUDEBAKER Builder of Champions Lucinda me ae oak

Page 114

112 POPULAR SCIENCE MONTHLY DeEcEMBER, 1929 Boys. dads, mothers ~—ma@ail the coupon for this &;

a ha Sr, ore el — ‘> a eta nm ‘ Home Mechanics, Inventors, Model Makers, Crafts- men! Now you can expect new things—amazing im- provements, new easy ways to make and repair a thou- sand and one different articles right in your own q Here is everything you need to gratify your creative instincts—and tomake ~ ag , too, Even in unskilled hands results are surprising. MAC is a strong, sturdy, ractical workshop—designed to perform the most dif. cult feats of woodcraft. _ 10 Days’ FREE TRIAL! We'll gjadly send you this s craftsman’s shop on approval for 10 days’ F TRIAL. ev ing necessary for a complete motorized workshop. 1-3 H.P. Motor; 8-inch Cireu- Tudor Morris, noted model plane builder, lar Saw; ‘36-inch Lathe: 4-inch Jointer: Sturdy Jig Saw and marking the wing position on his sail plane. teed to g oe kan uaran-

Great American Flyer TRAIN BOOK x FREE/

to give the est degree of service. Terms—as low as $5.94 per month. e things you can mage will be worth many times the small monthly payments. We'll pep zoe develop your hanical talents. A complete service, including instructions iy in. in hei ht 7] ona e o = 78 gnt, should be even with the end lene. is given, It fs clmole to master th art of wood turn- || trailing edge of the wing, and the 14-in. Write for C lete Detail end should project out in front of the Send us your name and address and we will mail literature illus-

wing. It can be slightly rounded in imi- Fang, nd cece eA ey Pove Teil Offer and boos a" tation of the pilot’s head to make the | | ™™™¥ term. Write today! - a a ° Mi Cn A its 48 colorful pages are _ glider look more realistic, if you wish. | ] pe —~- APPLIANCE CORPORATION “0

Be sure that this crosspiece is set at exactly right angles to the entering and trailing edges of the wing, as this piece is used for mounting the wing in place. Also make sure that the strip is set di- | rectly over the break, as it helps to bind | the two halves of the wing together. fitted with fun-making tdeas and suggestions Countless thousands of +: and parents have written for the American Flyer Train Book. It not only is a textbook of railroading ideas and sug- getions, but shows the complete line of American yer Trains and equipment. It also shows the complete line of Structo Automobile and Sand

wal tise tha book, and posse Reyasnil boop tt for | rize t . and most boys will keep it for T ak mm ts 3 * . oe ¢ Ee 5 or sekenend reference. It is the most complete cata- Next, make two “e-in. spring wire i Tae fog of high grade toys ever issued. wing clips as shown in the sketch on | ™™ Choice of 7 million boys 113 and cement one at the front and one Atlin tiie Gates ieetetiatas | ** the rear of the balsa crosspiece on the Reduce at ] a he ppg yi eee boys. apn Bena d underside of the wings. wants one for Christmas! Dads, too, are making ‘ ishi . s ° o,? sie wis ky mide pasting touch on the wing, it | AT Met a American Flyers are real trains—miniatures of & P nec! € balance an ; the qrocks Fn of the country, Real in every | see that one wing tip is not considerably harmless way oO » appearance an rilling per- . "s p aman tendy eed Eoceotinn, thee leaping, heavier than the other. If the wings are educational. Many exclusive fun-making features. out of balance, sandpaper the heaviest Tim AS Send coupon — compare! | wing tip until the wing does balance. BS FREE TRIAL Get the American Flyer Book and compare. Com- Make an actual size pattern of the omen pare the realistic designs of these trains. Compare body. Cut out the body from a % by 6 such features as Automatic Ringing Bell, High 1% by 8% in iece of balsa veneer ; MONTHS Speed Trucks, Automatic Signals, Electrically “16 DY 9 - Pp : . Remote-Controlled Track Switches, Automatic | The body should be sandpapered smooth sae TO PAY Mail Bag Catcher, Triple-action Remote-Control n AT LESS and Automatic Track Reverse Locomotives, In- CEMENTING BALSA TABLE TOP ! ; \ dividual Car Lighting, Automatic Couplings, STRIP’ TO CENTER 2) >BAISA STRIP selling direct makes THAN 20 Brass Trimmings, Enamel Colorings, Tunnels, OF WING = new low price pos- His ADA Bridges, etc. Compare the celebrated President's * = — sible. Satisfaction aie 4 Ss a), America’s finest train, the Potomac, and BLOCK’ ~~ CEMENT 7 puaranteed or your - . _— the Blue Bird Trains. Remember, American Fly- . money refunded. \ . WRITE fp p ers concede supremacy to no other train! 5" WING TIP Sr SCIENTIFIC ELEC. CO.® \“DETAIVS Read, in next month’s advertisement, how =| %6 te TS Br fm Ty my | ie you can get a valuable Sand Car free—on ELEVATOR 2 ‘ookline Ave. American Flyer Day, December 7th. Or ask a your Dealer for full particulars. Mail the w coupon for Free Train Book today. > oe == 7 sd srsstin btn Combination Exe Hs m TER foul inom) shipped on TS ic ays - approval, a manu ac ofl S > erp Hak. A comets Sel mee x ss or Ramet i ip, coves cut, Revel, at 2 ae fete hai St pole. '¥y HLP.AA.C motor ~ ¢ = ! wd a mg with ‘ge ae ag Write Tm °"§. & B. MANUFACTURING CO. Qu | 4603-L West 20th Street, CHICAGO ze N 5° 2 N WOO Samples of 33 Su L = S 25 S - . rare woods v2) 8 OF ALL KINDS _ $2.00 > - 1 & 20 cabinet and 20 inlay $1.75, ei t 2236 &. Halsted St., Chicago, Ill. i , —_ t Please send me, without cost, American Flyer ; \ big 7 ee © « 48-page, full-color Train Book. i IG ae ae SoTHICK ‘ By SS ER ee A ere ! om Oe Complete as shown. 7" swing, 24° metal bed. 3 Ni cicsscnernsnnes ».. || Dimensions of the model and methods of attach- Se elas a ae - RY... vncvccece Ceccccccccees State.........-. ! fag sutton, bein wing aieip. and Gis Hevater. Goodwin Mfg. Co., 435 Keota St., Dept..2, Ottumwa, lowa nd - eae ee eee

Page 115

DeceMBER, 1929 and tapered in thickness only at the rear. Next bend the 23 in. long piece of y-in. wire solder to fit the curvature of the nose of the body piece and cement it firmly in place. The elevator is 43 in. long and 1% in. wide and is shaped as shown in the draw- making it to the correct shape. The enter- ing edge should be slightly rounded and knife edge. extends 113% in. above the top of the body, and is made from %&-in. balsa veneer. Mount the rudder on the pointed end of the body so that it is straight up and down and neither turned to the right nor left. A small pin or needle will help to hold the rudder in place while the cement dries. When the cement on the rudder is dry, the elevator can be cemented in place and held by two pins while the cement dries. The elevator should be mounted to the body and rudder, and should be mounted without any spacing block TRAILING EDGE CEMENTED TO THE BALSA STRIP UNDERNEATH VIEW OF WING ATTACHMENT Method used in attaching the wings to the plane body by the means of spring wire clips. underneath, so that its surface will be parallel to the top of the body. After the cement is entirely dry, mark that you will always get it on in the proper way. The wing has been made detachable for convenience and carrying and so that it will come off without damaging the model in case of a bad landing; further- more, the adjustments can be made quickly and easily. After you have found the proper adjustment, however, you can cement the wing solidly in place if you wish; this should be done if the plane is to be used for stunting. For a trial glide, slip the wing on to the body so that the entering edge of the wing is about 2 in. back from the nose. Then gently launch the model into the air with a slight forward push. Do not throw it. As it is launched, the model should be held on an even keel or with the nose slightly downward. It should be grasped about the center of balance, in launching, because this will usually cause the nose to rise and the model to stall. After several glides you will find that a slight adjustment of the wing, either forward or backward, may improve the glide. After you have found the correct position, carefully mark it with a pen- cil for future reference. —— ing. The use of a pattern will simplify | very carefully and in a true and correct | position. It should be set at right angles | the rear edge sandpapered to a thin | The rudder, which has rounded edges, | which is just under the wing. It is not | advisable to hold the model by the tail | the front edge of the wing plainly so | POPULAR SCIENCE MONTHLY At Dan Beards School CARBORUNDUM i is used as regular equipment 113 7". Dan Beard believes in start- ing the boys right. Tuars why they are taught the proper care of tools—that’s why Carborundum Brand Sharpening Stones are part of the School equipment. Git goes without saying that a good Sharpening Stone—one that cuts fast and clean—leaves a keen smooth edge—should be in the tool kit of every man who appreci- ates good tools, well kept. qThe Carborundum Seda Combination Stone really is two stones in one—coarse grit side for bringing even the dullest tools quickly to an edge; fine side for imparting the smooth, keen edge that insures better work, quicker. q You can use this stone on plane bits, chisels, draw knives—nearly all of the edge tools found in the craftsman’s kit. CARBORUNDUM BRAND REG.U.S. PAT.OFF. SHARPENING STONES Sold by Hardware Dealers Everywhere Listen to THE CARBORUNDUM BAND Tuesdays, 7 to 8 P.M. (E. S. T.) Stations WABC, WCAU, WMAQ, WGHP, WKBW The CARBORUNDUM Company Niagara Falls, N. Y. Canadian Carborundum Co., Ltd., Niagara Falls, Ont. (Carb is the Reg d Trade Mark of The Carborundum Company for its Products ) (36 Page Name. = 9th Bathe eg Booklet Pl Address ce meee ae information on how to cus ae sharpen wood-working tools. @ This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

Page 116

YOU'LL GLUE IT BETTER with CASCO THE STRONGEST GLUE KNOWN 4 WATER-PROOF HEAT-PROOF

Casco—an all-glue dry powder— will glue practically everything— wood to wood, metal, glass, card- board, leather or paper—and glue it permanently. Easy to Use—Simply stir in cold water. Quality—being all glue with no adcled preservatives and mixed fresh as required, Casco always delivers maximum strength. No Heating—Mix cold and use cold on cold lumber. Eliminates the old fashioned glue-pot. Unperalleled Strength—A Casco glued joint is stronger than the wood itself. Tests 3800 lbs. per square inch on hard maple. Waterproof—Moisture or atmos- pheric changes do not affect Casco. Economical—One pound makes 1% quarts of high-powered liquid glue—and it spreads further. Results—Uniformly good on hard- woods or softwoods, Casco holds on difficult gluing jobs when all other adhesives have failed. Casco is an all-purpose waterproof glue used for years by leading aero- lane and woodworking industries. iow available to everybody in % and 1 pound packages. Casco is indispensable for Indoor and Outdoor Furniture, Cabinet Work, Boat Building, Ship Models, Screens and Screen rs, Sizing Walls, Auto Tops and Running Boards, Wall Paper, Lino- leum, Machinery Belts and hundreds of other gluing and repairing uses. SEND FOR YOUR TRIAL PACKAGE Prove to yourself the claims for CASCO by filling out completely the coupon be- low and package will be forwarded post- age prepaid. The Casein Manufacturing Co. of America, Inc. 15 Park Row, New York

- THE CASEIN MBG. CO. 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 paokage oi Casco Waterproot ue

ECIAL INTRODUCTORY TRIAL OFFER

POPULAR SCIENCE MONTHLY DECEMBER, 1929

eShipshape Home A Few Facts about Applying Glue HE operation of applying glue, con- trary to the prevalent idea, is one of the utmost importance in the mak- ing of any jointed woodwork. The glue must not only be of the best quality, but | it must be used in the right way. What are the common kinds of glue? Animal, casein, and liquid glue are the most common in home workshop prac- tice. Hide glue is made from the hides,

Test a joint carefully before applying glue.

horns, and bones of animals. Casein glue is prepared from the curd of cow’s milk. Liquid glue is made from fish stock as a rule, but sometimes from animal glue. What is the proper method of mixing animal or hide glue? The amount of glue needed should be placed in the inside pot of a double boiler, and from 1% to 3 parts of water to 1 part of glue, by weight, is added. The amount of water depends upon the grade of glue. The glue is then allowed to soak |

| for twelve, eight, or three hours, according | to whether it is cake, flake, or ground _ glue. After soaking the glue, fill the out- side boiler with water and put the inside | pot in place. Heat the glue until it be- comes a jellied mass, being careful to see that the temperature does not exceed 140° F. at any time. Glue should be applied when it is at a temperature of 135°: this leaves 5° for cooling on the brush. It | | |

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

Silver Ace Flying Models

ng Span, 30 inches unces 0 Wi (800 extra if shipped3by us) Weight, 344 0 pT yas panes all over the world ave learned the vast superiori SILVER ACE MODELS, thm ne sa Mr and Supplies. You save time, money and disappointment when you select a Silver Ace. With half the effort needed for assembling —_— or .~ yeu ~~ build a real little plane with the beautiful a sional finish of the Fae — ne eer, Their amazing durability means money well spent. _ Their performance brings thrill- ing reports of prizes won. Designed by aeronautical experts to meet all degrees of personal skill and every pocket book. Ready to fly, partly assembled, com- | = stg knocked down, or as contest sets. rices from $1.50 to $30.00. Sail Planes... Monoplanes... Biplanes...Seaplanes. Faithful miniatures of the famous big ships. Fairchild—Stinson—Fokker—Ryan— Cessna—Curtiss types. Sold by thousands of reputable dealers. If your dealer cannot furnish SILVER ACES, we will ship your order direct. Send 10 cents for our photographic catalogue, de- scribing 18 modern items and a complete list of real Silver Ace supplies. AERO MODEL COMPANY Dept. X12 @

CHICAGO make money. Sold by millions at higher Prices than chickens. Write at once for two — pon tell- ing how to do it, One is 48 es printed in colors, other 32 ; for Books 3 bm | gg You will be surprised a oe 111 North Wacker Drive 4 Breed squabs and TWO PLYMOUTH ROCK SQUAB COMPANY 616 H Street, Melrose Highlands, Massachusetts. Established 28 years. Reference, any bank or trust company,

BURN YOUR NAME ON TOOLS |

on the - tal, he writing on paper wits any metal, like ing on or_ pencil. Complete. Outfit S35 Prepaid Anywhere. “ ing iNgetrated cire free. Write to- OGRAF PEN CO. <SEx 1171-A East Stark $t., Portiand, Oregon

WADE BENCH LATHE Cap.,4 in. dia. x 12 in. el entire length of bed. -serew inside \. Hollow spindle. Turning, facing, toring, drilling, winding, thread cutting.

f No. 1 Lathe, plain headstock -- - $40.00 So. 3 Lathe, Poct-sonved hondete™ vrism, Cataieg ita om) 880) ually low pri je a Og sent tree. S°CTHE GEROLD COMPANY Dept. P. S. 11, 120 Liberty Street, Vert) Buy before the Tariff sends Prices Up! jakers tat

Famous M. Watch Extce tne Mode p 5228.00 Buy Direct from im ers $6.95 Save Money and This ie the eame Model that Famous Makers price at $125.00 Buy direct from Importers—Save Money Now—before inc sends prices up. Send no money— Pay the Postman after you have seen this wonderful wateh. We have Send No limited number only—Send your order Money today.

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Page 117

DecEMBER, 1929

is well to heat the work also, if possible. Hide glue must be fresh. For best results it should be applied not later than four hours after heating. Can hide glue be saved and reheated? Hide glue that has once become hard is weakened to such a degree that it is practically useless. The pot should be cleaned out thoroughly and a new batch made. Make only enough glue for your immediate need. Old glue left in a pot in which a new batch is being made reduces the value of the new glue 50 percent. A clean gluepot: lessens the chance of poor gluing and weak joints. How is casein glue mixed? Casein glue may be prepared in any ordinary pot or receptacle. The powder is added slowly to the correct amount of water as designated on the package. Stir the mixture vigorously until it is about the consistency of heavy cream. Allow it to stand for about 15 minutes and then stir again. The mixture may seem quite thick after the first mixing, but it will thin out after it is allowed to stand as above stated. work in hand. What are the advantages of casein glue? Glue of the casein type requires no heating and forms a strong water-resist- ant bond. It is therefore excellent for outdoor as well as indoor work. Con- venient to mix, it is equally easy to use as it sets slowly enough to allow ample time for adjusting and clamping joints. liquid glue? can be obtained by brushing on a thin sizing coat first and allowing that to dry before the final application. When liquid glue becomes too thick to spread easily, it can be thinned by the addition of water. In cold weather, however, it is usually water. Can liquid glue be used for any pur- poses other than mending and joining? Gesso can be made by using liquid glue. A mixture of 1 gill of liquid glue, 1144 cups of whiting, and 3 teaspoons each of linseed oiland varnish makes about one cup of fine quality gesso. Gesso is used as a deco- rative medium on picture frames and furniture. What kind of a brush is best suited for applying glue? soaked in water for from two to three days | and hammered so that the end fibers | become separated makes a good substi- | tute. As the end wears away, more of the fibers can be separated. If a brush gets hard, soaking it in water will restore it to its soft condition. Brush glue on quickly and vigorously and apply it to both parts to be joined. Next, clamp the work tightly so as to force the joint to- one and allow the glue to dry.

sufficient to place the can in a dish of hot |

Mix only sufficient for the |

What is the best method of applying In applying liquid glue a stronger joint |

A good bristle brush, preferably a regu- | | lar glue brush. However, a basswood stick |

POPULAR SCIENCE MONTHLY

ATKINS pee NEP od Bt toe -\ gee — SHIP POINT 2 = oy “on ATKINS ‘‘400" and** 4or"’ are the finest Hand Saws made Silver Steel Blades. Perfection Handles—no wrist strain.

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Nickeled steel adjustable frame, pistol grip handle; Atkins Non-Breakable or Silver Steel Blue-End Blades. ATKINS UNIOR MECHANI

A handy saw for junior mechanics, Boy Scouts; grown- ups, t0@. 20-inch polished blade, Cherry handle. Every tool user should have the four valu- Send able °.“W BOOKLETS shown at right. coupon for them now. ATKINS SILVER STEEL SAWS

115 Mr. Happy-Man Says:- “Give HIM an ATKINS Saw . for His Home- Shop or Tool Kit.” i not a bit too early to select HIS Christmas gift at your hard- ware store, NOW! For the man who has a home work- shop or is handy with tools, there's no finer gift than an ATKINS **400"" or ‘401’ Hand Saw. It will make him happy on Christmas morning and every day he uses it. Its ‘‘Silver Steel’’ blade will cut faster and easier than any other saw he ever used; its Perfection Handle of Solid Rosewood ives the saw balance as well as eauty, and eliminates all wrist strain. He'll use one of these famous saws, for a lifetime. For boys,who like tools, an ATKINS “‘Jun- ior Mechanic’ Hand Saw is the ideal gift. It will make any boy happy and encourage him to use good tools. Dozens of other fine ATKINS Saws for home craftsmen! Hack Saw Frames, with Silver Steel Blades, which cut TWICE as fast, and last six times as long. Back Saws for fine bench work. Circular Saws. Knives. Sets, etc. Compass and Keyhole Saws. Band Saws, all sizes. Machine Cabinet Scrapers, Saw Filers, Saw

Mail This to— E. C. ATKINS & CO. Est. 1857 4728 S. Illinois Street, Indianapolis, Ind. Send me Free Booklets, *‘Saw Sense,”’ [] “*Saws in The Home,” [) ‘*Dado Heads,” [ “Circular Saws’; [] Also details of your offer to pay $10 for best photo of a home workshop each month. BRIO . o.0'5.steeos on ccueppnesistenedans@eec meine eee C ih B h:0din-s.n:« 06:92 40 esbre'ej0inde@ ad bene ees Ie ene ee ee <i an. con anumsaieapinsmamaetnenentieme ann @ This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

oe eee me eS ee ee ee ee re eS ors ee ee ee es ee

Page 118

SHIP MODEL WITH ELECTRIC LIGHTS FOR ONLY $650 We furnish you with all the parts cut perfect . . . no trouble to fit them together . . . and in very little time you will have a beauti- ful Ship Model that you will be proud to own. Place it on your Radio or Mantel and light it with the electric equipment that comes with each model. Your Model will then give you the true effect of a ship at sea sailing along on the quest of adven- ture.

We have the following Models, all parts of which are cut to fit and ready to put together. A complete diagram and instruc- tion sheet with each Model, so | numbered that you cannot go wrong Models and Dimensions FLYING CLOUD 261/"long 714” wide 19”high SANTA MARIA 27" “ 10" 25” « MAYFLOWER 30” < 10” “ 26” « LAPINTA 627” 12" * gre | CONSTITUTION32” “ 10" « 3” « Every Model guaranteed money back if you want it. We will send you any of these above Models C.O.D. anywhere in the United States. Foreign orders must be accompanied by U. S. Money Order or Check. All Models shipped same day as order is received. Model Woodworking Company Dept. B Perkasie, Pa.

POPULAR SCIENCE MONTHLY

Getting Longer Service from Hack Saw Blades ANY machine hack saws are waste- ful of saw blades, especially when large quantities of small- sized stock are cut. On stock up to 3 in. in diameter perhaps only one third of the length of an 18-in. blade is used. It thus happens that blades are sometimes discarded when they still have two thirds or more teeth that are practically unused. One shop em- ploys a_ simple method for obtain- ing further service from the blades. When one section of the blade is dull, a short block of steel or iron is placed in the chuck to set the bars being cut farther ahead. —H.L.WHEELER.

A spacing block to distribute the wear. Fixture for Holding Thin Work to be Ground IFFICULTY is often experienced in disk-grinding thin pieces like the flange shown at A in the accompanying illustration. The grinding of thin pieces is considered an unpleasant opera- tion, as it brings the fingers close to the grinding wheel. However this trouble can be re- medied in most cases by using a work-holding fix- ture. The fixture shown for holding part A is simply a wooden frame with a recess cut How the wooden at B about 3 in, $inding fixcure for deep and of the j same shape as the flange to be ground. The upper member of the fixture is cut in two at C, thus forming two jaws which can be clamped on the work by tightening nut D.—LEONARD KEISER, JR.

Handle for Sheet Metal HE difficult and often dangerous job of handling large sheets of metal may be made easy and safe by the holder illus- ‘ trated. It is simply a loop of 56-1 -in. steel rod ‘just large enough to fit a man’s hand, and with about 3 in. at one end turned back near the loop, leaving a space large enough to admit the metal. The turned-back portion is drawn down to a wedge

Top sheets are easily moved with this tool.

shape at the end.—Josrepn C. Coy ze.

DECEMBER, 1929

with this OFFER

Why pay an extravagant price for strength—get all equipment you require and excellent course of instructions for only $5.00. i Develop muscies of a super-man. Get strong and amaze friends. We show how to easily master a which now seem difficult—if you want physical culture for your health’ sake, this equipment m what you need. Save at least hall a ten cable chest expander adjustable to resistance up to 200 Ibe. ade of new live extra strength, springy rubber to assure long wear ‘and pone resistance 72 need for real muscle development. also get a pair of tented hand grips fer developin, ee Sloe and forearms. We include wall exercising parts which Permit you to develop your back, arms and lege—a real muscle necessity. Busi- their legs. Develop leg muscles with foot strap which we furnish. This will zive you speed and endurance—but that isn’ all you get. In addition we include by specially written course which contains Pictures and diagrams showing how to develop any part of your body so you quickly get on with these exercises and gain Oe ae advantage from their use. etn SEND NO MONEY this special offer. Sign name and address to coupon and rush to us. We send your ten cable chest de- s*22\\ veloper, wall parts, a pair of hand gripe, foot strap and the course 4 return mail. Pay postman 5.00, plus postage on arrival. oi you send check or money order in advance, we pay post- ) GUARANTEE All Crusader products are guar- anteed to give saahe satisfac-

tion or money bac Crusader Apparatus Co., Dept. 612, 44 Parker Ave., Maplewood, N. J. I accept your offer. Send me ard described in your advertisement by return mail. I will pay the postman $5.00 plus postage on arrival. It is understood if I am not entirely satisfied after exam- ination I can return the goods and you will refund my money Note; No %. O..D. Orders to Foreign Counties or Canada es

watch. in square, emee ane me “cushiein to ial, Matinfaction | oT RIINS, 99. J NS,

scousate & teed. Rush order. Gand po money. 685 Broadway, N ew York, Det Dept. ‘12-F-91. ANY BOOK IN PRINT ™ Delivered at your door, Pay the po an age. Standard authors, ‘toca editions’ » —- books, all at biggest savings. Be sure to send postcard for Clarkson’s catalog. FREE Writefor our great book catalog. This catalog is a short course in literature and is so used by some of Amer- ica’s leading universities; 300,000 book lovers buy from it. Free if you write now. CLARKSON PUBLISHING CO. 1120 CLARKSON BLDG., CHICAGO, ILL. 110 Volt—complete plant ELECTRIC heey Seen =7 7 LIGHTS ANYWHERE

Household Electrical Appliances, inotail it yourself. Write for circular. o.W onan 8 a sons $1 4750 Minneapoiis, Senazete.

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DecEMBER, 1929 # Easily Constructed Modernistic Desk The desk adds a modernistic note room. to any touch of the modernistic to his room teresting project. The construction is simple, and the finished product is serv- iceable and attractive looking. In its construction there are few points that require any further explanation than that given by the drawings. The horizon- tal portion of the desk is fastened to the upright supports by means of bolts. Slots are cut in the horizontal pieces large enough to receive the nuts. The bolts are then put through holes drilled in the side- pieces and in the edge of the horizontal pieces so as to engage nuts set in the slots. When the bolts have been drawn up tight, the fastening is very substantial. is held in place with dowels. The type of finish to be used depends wholly on the color scheme that is carried out in the room in which the desk is to be placed.—F. W. MEcow. - call m aad a, DESK TOP 18 - a 133-4 ao 13% +~ DRAWERS sN ais ” le —*}~ 8 -> Uy -.. oe DESK TOP fe "sie FASTENING vid | all _ 4 -93 - is 4 ogi 9 % aq = SIDE | YOR anyone who wishes to add a little | and is handy with woodworking | tools, the desk shown is an especially in- | FRAMES |” DRAWER The center division between the drawers | \\ POPULAR SCIENCE MONTHLY | Mans Bug” asa COAL THIEF: & Tycos for the Home & Trcos Office Thermometers An aid in promoting human efficiency. Tycos Bath Thermometers Tycos Home Set Bake Oven Thermometer, Candy Ther- mometer, Sugar Meter. The secret of accurate results in cooking. Tycos Wall Thermometers To help you to maintain a temperature in your house conducive to good health. Tycos Quality Compasses Beos Fever Thermometers Tycos Stormoguide Forecasts the weather twenty-four hours ahead with dependable accuracy. Tycos Hygrometer To enable you to keep the humidity of the atmosphere in your home correct at all times. Tycos for the Medical Profession Byeos Sphyg Pocket and Office types. Tcoa Fever Thermometers. Tycos in cAviation A full line of Aviation Instruments for ships and airports. Your dealer will show them to you. Ask eee for booklets on any of the above. Bulletins on request er, Recording | PITTSBURGH, PA. BVERY large power plant depends on re- liable controlling instruments. In the Colfax plant of the Duquesne Power & Light Co. 152 Seos Instruments are in- stalled. The 60,000 K. W. 3 element cross com- pound turbogenerator—one of the largest in the world—uses so much steam that a vari- ance of 1% means a loss of 6,000 lbs. of steam per hour—and it takes a lot of coal to produce 6,000 lbs. of steam. Yover instruments are doing this impor- tant job of controlling the operations of main turbines—condensers—hot wells— feed pumps—oil coolers and transformers in this most modern piant. In the past many of these operations were carried on by Blind Man’s Buff or Guess Work, dependent on the experience of the plant man, and the losses through unpro- ductive coal consumption were tremendous. feos Instruments naw save the world thousands of tons of coal. TO MANUFACTURERS If your process is annealing — baking —steam cooking — boiler regulation — vulcanizing —any- where that temperature control isa factor—Zawor instruments are made to do the job. Informative literature will be sent on any type of instrument on request or— Our engineers will consult with you on the ap- plication of Zjcos to your particular problem. Taylor /nstrument Companies Main Office and Factory: ROCHESTER, N.Y., U.S.A. Canadian Plant: Jcos Building, Toronto SHORT & MASON, Ltd. Manufacturing Distributors in Great Britain TH E -~ SIATEH.~ SENSE ~ INDICATING RECORDING 6 CONTROLLING INSTRUMENTS HAVE SAVED THOUSANDS OF TONS OF COAL AT THE COLFAX PLANT OF THE DUQUESNE POWER & LIGHT CO., INDUSTRY Assembly of the desk, and details of the drawer, end pieces, and fastening for top. lycos Tempera ture Instruments INDICATING ~- RECORDING ~ CONTROLLING —

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© a .TFor the Radio-electrician Te Remington Pocket Knife R4548 is manu- factured expressly for Radio and Electrical use and makes a special appeal to all members of the wiring fra- ternity, professional or amateur. Equipped with two forged steel Bees the finest quality, a 2%" sheepfoot blade, and a combination of wire-stripper and screwdriver, locked in place by safety-catch when open, it readily adapts itself to man practical uses in tinkering wit radio sets or installing general electric equipment. Blades—are tempered and hard- ened to take a keen edge and retain it, and are hand-honed to razor sharpness at the factory. Handle — is Genuine English Cocobolo with bolsters of nickel silver, light in weight but durable. A strongly made and finely fin- ished knife. An ideal pocket- companion for the man or boy who wishes to “build his own.” Ask your dealer to show tw the Remington R4548. If he hasn’t it in stock, send his name with $2.00 to Remington Cut- lery Works, Bridgeport, Conn. and it will be forwarded promptly. REMINGTON ARMS CO., Inc. Originators of Kleanbore Ammunition 25 Broadway New York City Remingion, © 1929 B, A. Co. et a eae sn a f ' PRACTICAL GIFTS! None more desirable than a GERSTNER Tool Chest for Machin- ists and Toolmakers. Get Free Catalog and choose your own, "GREER Er | POPULAR SCIENCE MONTHLY The Midget “Five-in-One” Slide Rule Net Farbeg., Binary had and. Sas epost Spotlights Brighten a Christmas Tree M's novel Christmas tree effects can be obtained by using the homemade spotlight illustrated below. Its cost is so far below that of the commercial type that it can be conseidred Many futuristic and artistic lighting effects can be obtained by using colored spotlights. as negligible, and at the same time its ef- fectiveness is the same. A tree lighted in this manner is shown, and with a little practice and a few trials many other artistic effects can be arranged. Drill or punch a series of holes in the bottom of a regular square oil can, and cut a 4in. diameter opening. Place this hole so that its center will be opposite the filament of a 250-watt stereopticon lamp, | which is held in a suitable porcelain | socket. Solder or bolt on the three clips | that hold the short focal length lens in place. Both lenses and bulbs can be bought at photographic or motion pic- ture supply houses. Wire the socket, put a bolt through the | screw hole, and fasten it to the can with a wing nut, so that it can be shifted readily. Carry the wire through the filling hole to a plug. As the spotlight will get hot, place it on two bricks for safety. For colors, use colored glass, theatrical gelatin, or, if nothing else is available, plain thin colored tissue paper placed back of the lens.—J. S. The spotlight is made from an ordinary oil can and a lens, and a 250-watt lamp is placed inside. ScraTcHES in both enameled and var- nished furniture can be temporarily con- cealed with ordinary wax crayons. Polish the retouched spots lightly with a soft cloth to bring out the wax luster. DEcEMBER, 1929 factory prices on 21-JEWEL—Thin Model The Insured Watch The only high-grade watch 7 solddirect fromfactory! 4 Imagine being able to pur- chase these magnificent thin model watches at lowest £ factory prices on easy pay-/ ments out of yourincome, or forcash! Letussend you one¢pg | of these marvelous watches} —you are under no obligation}/) to keep it. You'll agree it is} the world’s greatest watch value. Write for free 6-color book acts! and learn the truef 6-Color Bock If you write at once we will send beautiful style book, showing lowest fac prices on these lifetime insured watches. Thousands sa way. Write STUDEBAKER WATCH COMPANY | Directed by ‘he Studebaker Family—known for Three-quartere of a century of fair dealing a [ pene. Ni:ie4,”" | Sough Bend, Indtons Now...AtA Startling New Low Price... UltraViolet Sunshine Natures Miracle Worker! = world’s largest producers of ve. ical therapy apparatus for phy cians and hospitals are now announc an ex- tra-quality Ultra-Violet sunshine lamp at an unbelievably low price. Amazing twin- arc feature—four carbons radiating at one time—gives double radiation. All the effi- ciency of any carbon-are lamp for home use, regardless of price. Produces genuine ultra-violet, infra-red and visible rays. Ultra-violet will keep you feeling fit and looking your best. Gives you a glowing tan and a keener mind—protects agai colds and flu. Need inst, ed Ld all babies and children. Doctors prescribe it for many Sent Y. We invi ve invite you to test F , aoe By oper Lam our home. or 10 ae Write us Be ones for de- Trial tails of our 10 Day ‘Trial er and our fascina beoklet on Ultra-Violet. = NATIONAL HEALTH APPLIANCE Corp, The_!s™p may be ded 1676 N. Claremont Ave., Dept. W-390 ward. for seven s as shown. has four car bons radiating at one time— double arcs in- stead of single. FLY THIS COMBAT MONOPLANE This realistic copy of a mil- me 16 an unu- ked in unbreakable container, $1.00, st- ity Mina Canada. Order today, giving full address. Satie- plete ihe Midiand Model Works, Chillicothe, Ohio e an » f (We cannot make C.0.D.shipments. No retail catalogue issued) Advice for POPULAR SCIENCE MONTHLY readers regarding safe and profitable investments. See Page 4.

Page 121

DecEMBER, 1929

the foot piece can

Compact Shoe and Polish Cabinet

easily worked wood may be used. is made up of two ends % by 10% in. back 4% by 20 in. by 5 ft. 5 in.; boa with fourpenny common nails. Make five shelves F 54 by 11% by Cleats H, % by % by 20 in., may N MAKING the combination shoe case and polishing outfit shown, any folded up and hidden behind the two doors. It by 5 ft. 5in., one top % by 10 by 20 in., one bottom the same size, and one plywood rds may be used for the latter if preferred. Assemble these pieces with sixpenny fin- ishing nails, fastening the back in place 20 in. and bevel their back edges as at G, and the front edges as shown by the detail. be fastened with 1-in. brads at a distance from the back edge of each shelf G to suit the shoes to be kept thereon. Fasten | these in place at about the angle indicated with sixpenny finishing nails, watching = he

OF SHECF | EDGE G < ; Ow a F -

eae ten

oO 8 DETAIL F *

AMOI R= = ae a | i He HH | oat SS oe, pai cen i 4 B aT C i 38 Af 3 *0 a 2 ) | ] ¢ “Hy ad | Assembly of the complete shoe case and polish- . ape Note position of foot-piece bracket. a The bracket that holds be AR

POPULAR SCIENCE MONTHLY

= —e r un of WHAT YOU DON'T SEE CD\ GEIR GT FES Ai x

Fifteen NICHOLSON FILES ne HAT YOU SEE: A dark cone shedding a white light on a table covered in green... a leveled cue, the click of two ivory balls ...a masterly shot completing a run of fifteen. WHAT YOU DON’T SEE: Before the match, the players roughing the tips of their cues —so that they will grip the balls better — with a Nicholson Flat Bastard File. There are picturesque uses for files and thousands of common- place jobs that only a file can do. From the pocket billiard cham- pion to the mechanic in a small town garage, every one can find uses for these sharp cutting, time tested tools. At hardware and mill supply dealers’ NICHOLSON FILE CO. Providence, R.1.,U.S.A. t A FILE FOR EVERY PURPOSE

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

Page 122

120 POPULAR SCIENCE MONTHLY DEcEMBER, 1929 Get an IDEAL MODEL AIRPLANE for Christmas! + ae American: Eagle The Most Advanced Development in Flying Model Airplanes Wing Span: 26 in. Weight: 3% oz. An entirely new, light-weight, fast- flying Model; distinctive appearance, ~ realistic in flight, unique in construé- ~~ tion details. Balsa wood fuselage, with specially designed aluminum bulkheads; built-up wings with ready- formed ribs; removable tailfassembly.~: Finished in modern color dgcorations.~" Just the Model Airplane you. have been wanting; simple in construction, and a reliable fabt yer. Construction Set:* wmigans Model: The IDEAL FORD MONOPLANE An accurate, 3-ft. Scale Model of this famous ship. All parts miniature dup- licates of the original. Build it the IDEAL way; we guarantee it to fly when correctly constructed. Every- thing required in Complete Construc- tion Outfit, including Plans and ‘*In- ee Pe eta erere $8.50 The IDEAL ‘Jew York - Paris Monoplane An exact Model reproduction of the most famous Airplane in the world—‘Spirit of St. Louis.” 3-ft. wing span, and a won- derful fiyer. All parts and fittings are realistic and everything required to build } area comes in Complete wee I Ono KKER MONOPLANE; 3-ft. Model “North Pole’ type. Complete Con- a rr $8.50 Cecil Peoli Racing Airplane; 36 in. size. A ampionship winner. Com- PEM 066 ccecaccrecceses $3.75 Ask for IDEAL Model Airplanes at your local store. If unobtainable, send your order direct to us and delivery will be made at once. €4-pg. Catalogue Models, Parts, Sup- plies and Materials for Builders: 5c IDEAL AEROPLANE & SUPPLY COMPANY, Inc. Betablished in 1911—18 Years Ago 28 West 19th Street, New York City carefully while the nails are being driven to be sure that they do not come out of the side of the shelf. Cut out two % by 10 by 16% in. ply- wood doors. In fitting them, hang with 134-in. brass butts placed as at J, with a stop 4 by 2 by 6 in. glued and bradded as at K. Fit a brass spring friction catch at D to hold each door, with the striker on the. inside of the bottom. A 3-in. brass knob should be attached at L. Fasten piece B into A with glue and 1-in. No. 9 screws. Make a foot rest and fasten'to B as suggested. Hang piece C to B with a 3-in. iron strap hinge, place the _assembled pieces on the bottom of the closet, and fasten with 2-in. hinges lo- cated as at M and back far enough to allow the doors to open and close freely. The back and ends of the inside of the -closet, together with the pieces A, B, C and. the foot rest, should be painted black, -for any other color will be defaced by spots of shoe blacking. The remainder of the case may be painted, lacquered or stained to suit. - Straps of cloth or leather or wood cleats may be fastened to the walls of the closet as indicated, to receive brushes, boxes, and bottles of ‘shoe polish, and other accessories. —C, A. Embellished Copper Letter Openers After the blank has been cut, the operations are confined mostly to the hammer and anvil. OTHING in the line of decorative metal work is easier to make than a hammered copper letter opener. Aside from being work well within the limits of skill possessed by the average worker, the finished artjcle is one that may well grace the finest mahogany desk or table. As to form, several general shapes are illustrated, but there are hundreds of de- signs that can be used. There is one limitation, however: the handles should be 3% in. long and the blades at least 5 in. long. These proportions will give the best results both as to attractiveness and balance. After the design has been chosen, lay out a pattern of the knife on cardboard and then transfer the shape to No. 16 Where an Inch is an Inch! You can depend on every genuine Russell Jennings Auger Bit to bore a hole exactly the size stamped on the bit. For absolutely accurate boring, insist on the genuine Russell Jennings Auger Bits. Full name stamped on the round. Sold at all good hardware stores. The Russell Jennings Mfg. Co. Chester, Conn. Fuvsell Fennings AUGER BITS Own Cards, stationery, labels, Paper, circulars, tags, menus, book ete, 4 De Job Press, $11, $29; Rotary $149. Print for Others, Big Profits. All easy, rules sent. rite for catalog of presses, type, paper, cards, envelopes, paper cutters. The Kelsey Co., P-33, Meriden, Conn Over ihe Mountains HUNDRED FIFTY-NINE Think of it! FIVE MIL _ -4 over Fy mountainous country burning only ELEVEN GALLONS OF GASOLINE, Imagine more than FIFTY MIL ES TO THE GALLON, That is what the WHIRLWIND CARBURE poset DEVICE does for D. R. Gilbert, enough of a saving on just one trip to more than pay the cost of the V hirlwind. THEWHIRLWIND SAVES MOTORISTS Minions OF Dowars YEARLY Whirlwind users, reporting the results of their tests: are amazed at the results they are petting. Letters keep streaming into the office telling of mileages all the way from 22 to 59 miles on a gallon, resulting in a saving of from 25% to 50% in gas bills alone. Mark A. Estes writes, “I was making 17 miles to the gallon ~ my Pontiac Coupe renew. =. ,the Whirk wind, I am making 35.5 mike. to the nies . Goerzen writes, “34-6/10 = J with the Whirl wind, ora ~~! of 21 miles to the gal R. J. Tulp, “The Whirlwind peed the mileage on ayh. truck from 12 to 26 miles to agallon and 25% ns Car owners all over the world are saving money every day with the Whirlwind, besides having better operating motors. Think what this means on your own car. Figure up your savings—enough for a radio—a bank account— ed pleasures. Why let the Oil Companies profit by your waste? Find out about this amazing little device that will pay for ee every few weeks. ALL CARS In just a few minutes the Whirlwind can be installed on any make of car, truck or tractor. It’s ly less work than changing your oil or putting water = the Gaiters. No drilling, tapping or changes of any kind r) to work perfectly on an; make of car, truck or tractor, large or email. new mode! or old m: el. The more you drive the more you will save. alesmen and Distr ibutors wanted Free Sample and $100.00 eek er Whirlwind men ms making big profite suppizine this ~ya selling device that car owners cannot afford to be Good territory is stillopen. Free sample offer and full particuiars sent on request. Just check the coapon. uarantee - No matter what kind of a car you have—no matter how big a gas- eater it is—The Whirlwind will save you money. We absolutely guar- antee that the Whirlwind will more than save its cost in_gasoline alone within thirty days, or the trial will cost you nothing. We invite you to test it at our risk and expense. You are to be the sole judge. ——-—~——-~~-Fgee Trial Coupon— -----—--- Fottwing te. 999-47-A Third St., Milwaukee, Wisc ay send me full particulars of your Whirlwind Carbureting device and free trial offer. This does not obligate me in any way whatever. GES io 000i659050506080000 STATE.......ssesece =" here if you are interested in full or part time salesman post @) This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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a St ~~ DEcEMBER, 1929 POPULAR SCIENCE MONTHLY 121 Acopper blank; B one edge hammered; C both edges hammered; D edges removed; E filed edges; F blunt chisel finish; G bent handle. gage copper by drawing around the pat- tern with a pencil. With a pair of metal shears cut the copper to the line. The metal blank is now ready for the ham- mering operation. The illustration A shows the blank as it is cut from the sheet copper, B the knife after the one edge has been ham- mered with a ball peen hammer. The other edge is now hammered until the bow in the blade disappears and it again becomes straight as in C. This brings the edges down to a knife-edge thickness. With a pair of shears, cut the ragged edges from the blade. This can be done with considerable ease if one handle of the shears is placed in the vise, thus allowing more leverage. The knife after this operation is shown at D. With a file, clean up the edges until the blade has a good, smooth, straight cutting edge as at E. The handle can be completed by using a blunt chisel as at F; this gives an attractive lined effect. Another method is to bend the handle as shown at G. There are as many actual variations for the handle design as there are for the letter opener as a whole. Coloring the knives with a water solu- tion of liver of sulphur gives a dark copper-colored tint to the knife and thus adds to its beauty. Finally, polish it with | a clean cloth and apply any transparent | metal lacquer.—Dicx HUTCHINSON. Dimensions of the knife and the plain, ham- mered, and blunt chisel designs for the handles. » REGISTERED TRADE MARK Butiooby N EW! Real fun with This is the No. 5 Set Packed in wood cabinet. Contains 54 chemicals and pieces of apparatus. Manual of Instruction explains 360 experiments. A wonderful set for any boy who wants to have some real, helpful fun with chemistry. $5.00. The TELEPHONE BOOK with The MAGIC MICROPHONE Electric Telephone ! Read the inside story of the telephone and build a real, electric_broadcasting telephone of your own. You. can also make a Super-sensitive Microphone that will enable you to hear a fly walk; a Detectophone, a Stethoscope and other sound-detecting instruments. ‘You can have great fun experimenting with them, and learn about telephonic and micro- phonic science—the science of sound transmission and detection. Complete Outfit in New Book-Box All parts, wiring and apparatus are included teeta Muoked fas" umaue $5.00 everything pac n Book-Box........000eeee0e0088 ” Sold by Toy Departments and Book Stores. Ask for The TELEPHONE BOOK. If unobtainable, we will send direct upon receipt of price. Chemistry ! EARN the Science of Chemistry with CHEMCRAFT; work hun- dreds of wonderful and useful ex- periments; make soap, inks and dyes; test-foods, water and soil; pro- duce amazing chemical changes and perform surprising tricks of magic. All these experiments, and many more, can be done. with CHEM- CRAFT. These NEW sets are greatly improved; the finest we have ever made. More chemicals, more apparatus, more and better ex- periments. CHEMCRAFT is the original and most popular chemical set. Get one this year and have lots of interesting fun. - Six Sets to Choose from: No. 1—$1.00 No.5 —$5.00 No. 15—$15.00 No. 3— 3.00 No. 10—10.00 No. 25— 25.00 Each set complete with chemicals, apparatus and Manual of Instruction, Look for them in the Toy Dept. If unobtainable, send your order direct. Try Chemistry for 25 cents Get CHEMCRAFT Junior the set that will introduce you to chemistry. Sent postpaid for only 25 cents. The Boys’ Home Workshop Design and ake M Useful Articles of Wood! WOODCRAFT ill — introduce you to the _, cal at ruct ‘and 7 Saeae ~ of , - . Eae! i te He — arorkshop for RO goodie errs p Plans and ail materiale ft oanat holds elves, necktie holders Tew a i sliders, motor boats, desianarticlés. WOODCHAFT acer than tooled — boys, and is mae ? Go and how to do Pak ete No. 5—~ ae Sold in 7 ae No. 10—$10.00 aa Prints + We will send m = Eegnceare... Mf nm pt : = Send for FREE MAGAZINE for Boys Full of fine ideas on Chemistry, Wood-Working and Electricity. Tells all about the sets mentioned above. It's free to boys, just ask for your copy. The PORTER CHEMICAL COMPANY 76 E. WASHINGTON STREET HAGERSTOWN, MARYLAND

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122 Building Furniture in Unused Doorways By CHARLES A. KING “WHAT unused doorway in your house, through which no mem- ber of the family ever passes, may be easily fitted with built- in furniture, which, if constructed sepa- rately, would occupy considerable space in the room. The drawings below show how to build a desk, a linen closet, a service closet, or a combination breakfast table and iron- ing board. Some of the designs, as in Fig. 3, are adaptable to other pieces such as a buffet or a china closet. The design in Fig. 1 can be used in building a desk and bookshelves, or merely the bookshelves. The combina- tion desk and bookshelf takes the place of two bulky articles and extends only about 6 in. into the room. The case A is made about % in. narrower and shorter than the doorway itself. The shelves may be either grooved or nailed into place. The desk lid may be supported most easily by using brass hinges as at D and chain desk-shelf supports as at E, but regular desk stays may be fitted if pre- ferred. The top of case A and the desk shelves B and C are the full width of the case at these points, but the other shelves are set back about % in. so that the outer * edges are not quite flush with the edges of the sides of the case. Cloth or thin wall board can be used to cover the back of the case. After the completed piece is placed in the opening and fastened securely, a piece of molding F, % by 1% in., may be mitered around the case to hide the joints and attached with brads. If the unused doorway is in the kitchen or the living room, it may be used to con- tain a breakfast table and ironing board as shown in Fig. 2. First fit and fasten the crosspieces as shown in section at A. prwlenegee wwe dans fonnnantnapanion nnd) POPULAR SCIENCE MONTHLY The table top, which is made of 34-in. plywood, is fitted to swing freely and hung from 3- in. brass hinges screwed to the closed door at the back of the case and to the table top, as at B and C. These hinges are so fastened that when the table top is lowered for use its underside will rest on the piece A, which serves as a sup- port. The ironing board should be hung with smaller hinges from the underside of the table top, so that it will not interfere with the dropping of the larger piece. When the table top is locked in a vertical position, the ironing board may be lowered for use. The upper part of the opening may be covered with a curtain on a roller, the lower with bright colored cloth. The table top is kept in a vertical position by a strong bolt fastener, and metal clips made as shown hold the ironing board. N OLD chest of drawers, which is easily obtainable, may be used in making the linen closet shown in Fig. 3. Shelves are built above to contain linens and are con- cealed by doors of %-in. plywood. If a search of used furniture stores fails to re- veal a suitable chest, the making of one will be an absorbing project for the am- bitious homeworker. Trouble in sweep- ing can be avoided by filling in the space between the feet of the chest with a panel. Cross sections of the upper and lower parts are shown in the upper part of the WALL BOARD ost 7 ROLLER SHADE / / / PLYWOOD DECEMBER, 1929 Combination ironing board and breakfast table built into an unused kitchen doorway. The table swings down when needed. drawing. Section X shows the construc- tion of the lower cabinet, section Y the upper. The service closet in Fig. 4 should be made deep enough, by building an ex- tension out or in, to contain the vacuum cleaner. A diagram of this construction is shown in section X. Wall board forms the back of the closet, the original door the front. Brooms, mops, aad dustpans may be held in place by the cleats. A which may also serve as shelf supports. The wall board back is stiffened by cleats B, which support shelves placed as de- sired to hold dusting cloths, cans of pol- ish, and cleansers. IF MORE than moderate exertion is re- quired to make a woodworking tool do its work, the tool is dull, improperly ad- justed, or being incorrectly used. a BOLT UNDER TABLE TOP ee HINGE A ' *_ IRONING BOARD SECTION Y SECTION X @ @ — col 1 elves ss pin ee i 87 Fa : | " i t 7 | f - 11 B 1] . i or a SA P i \ ty Wt f — ° , bs ° ° | ees Seer S| oe | ° x 2 | xi ( — We 7 / \ l . SECTION x Fié. 1 DESK AND BOOKSHELVES FIG. 2 BREAKFAST TABLE AND IRONING BOARD. DUST PANEL” fig. LINEN CLOSET IN BATHROOM FIG. 4 SERVIGE CLOSET Four suggestions for utilizing those superfluous doorways in old houses which are rarely or never used. Built-in furniture of this type has the great advantage of using no extra wall space.

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DecemBer, 1929 ‘What ? Learn Music VY Mail ? they laughed ae es, I cried, and [ll bet POPULAR SCIENCE MONTHLY we Ty oF a money I can do it/” T all started one day after lunch. The office crowd was in the recreation-room, smoking and talking, while I thumbed through a magazine. “Why so quiet, Joe?”’ some one called to me. “Just reading an ad,” I replied, “all about a new way to learn music by mail. Says here any one can learn to play in a few months at home, without a teacher. Sounds easy, the way they -tell about it.” “Ha, ha,” laughed Fred Lawrence, “do you suppose they would say it was hard?” “Perhaps not,” I came back, a bit peeved, “but it sounds so reasonable T thought I’d write them for their booklet.’’ Well, maybe I didn’t get a razzing then! Finally Fred Lawrence snecred: ‘Why, it’s absurd. The poor fellow really believes he can learn music by mail!” To this day I don’t know what made me come back at him. Perhaps it was because I really was ambitious to learn to play the piano. Anyhow, before I knew it I’d cried, “‘Yes, and I'll bet money I can do it.” But the crowd only laughed harder than ever. , Suppose 1 Was Wrong— As I walked upstairs to my desk I began to regret my haste. Suppose that music course wasn’t what the ad said. Suppose it was too difficult for me. And how did I know I had even the least bit of talent to help me out. If I fell down, the boys in the office would have the laugh on me for life. But just as I was Grove. After lunch it rained, and we all sat around inside looking at each other. Suddenly some one spied a piano in the corner. ‘‘Who can play?” every one began asking. Naturally, Fred Lawrence saw a fine chance to have some fun at my expense, and he got right up. “Ladies and gentlemen,” he began, “our friend Joe, = music-master, has consented to give us a recita That gave the boys a good laugh. And some of them got on either side of me and with mock dignity started to escort me to the piano. I could hear a girl say, ‘‘Oh, let the poor fellow alone; can't you see he’s mortified to death.” The Last Laugh I smiled to myself. This was certainly a wonder- ful setting for my little surprise party. Assuming a scared look, I stumbled over to the piano while the crowd tittered. “Play ‘The Varsity Drag’."’ shouted Fred think- ing to embarrass me further. I began fingering the ve. and then .. witha wonderful feeling of cool confidence . . . I broke right into the very selection Fred asked for. There was a sudden hush in the room as I made that old piano talk. But in a few minutes I heard a fellow jump to his feet and shout, ‘Believe me, the boy is there! Let’s dance!”’ Table and chairs were pushed aside, and soon the whole crowd was shuffling around having a whale of a time. Nobody would hear of my stopping, least of all the four fellows who were singing in harmony right at my elbow. So I played one ee Re ere after another until I finished with ‘Crazy Rhyt and the crowd stopped dancing and sin ~ "te applaud me. As I turned around to thank them, there was Fred holding a tenspot right under my nose. “‘Folks,"" he said, addressing beginning to weaken, my lifelong ambition to play and my real love of music came to the rescue. And I decided to go through with the Piano whole thing. green During the few months that Banie followed, Fred Lawrence never missed a chance to give me a sly dig about my bet. And the boys Tenor) always got a good laugh, too. ot ut I never said a word. I was | * see waiting —— for a chance to Cornet get the last laugh myself. (Plectrum, My Chance Arrives Things began coming my way What Instrument for You? Steel Guitar Drums and 5-String or Trombone Saxophone Sight Singing Voice and Speech Culture Harmony and Composition Automatic Finger Control Piano Accordion Italian and German Accordion the crowd again, “I want to apologize publicly to Joe. I bet him’ he couldn't learn to play by Piccolo mail, and believe me, he sure Guitar deserves to win the money!” Hawaiian “Learn to play by mail!” ex- claimed a dozen people. “That Traps sounds impossible! Tell us how ee you did it!" Ukulele I was only too glad to tell them how I'd always wanted to play but couldn't afford a teacher, and couldn't think of spending years in practice. I described how I had read the U. S. School of Music ad, and how Fred bet me I couldn't learn to play by mail. ‘*Folks,”’ I continued, “‘it was the biggest surprise of my life when I during the office outing at Pine 123 ht from the start, ere were no scales got the first lesson. It was fon % everything as simple as A-B-C. or tiresome exercises. And all it pe was part of my spare time. In a short time I was playin jazs, classical pieces, and in fact, anything I wan lieve me, that certainly was a profitable bet I ‘made with Fred.” Play Any Instrument You, too, can now teach yourself to be an accom- plished musician—right at home—in half the usual time. You can’t go wang with this simple new method which has siready own over half a million people how to play their favorite instruments by note. Forget that old-fashioned idea that you need special ‘‘talent.’’ Just read the list of instruments in the panel. decide which one you want to play and the U.S. School will do the rest. And bear in mind no matter which instrument you choose, the cost in each case will be the same—averaging just a few cents a day. No matter whether you are a mere beginner or already a good performer, you will be interested in learning about this new and wonderful method. Send for Our Free Booklet and Demonstration Lesson Thousands of successful students never dreamed they possessed musical ability until it was revealed to them by a remarkable ‘‘Musical Ability Test” which we send entirely without cost with our in- tormsting free booklet. # are in earnest about wanting to play vorite instrument—if you really want to sopiaess and increase your oulatite—aind at once for the Free Booklet and Free Demonstration Lesson which explain this remarkable method. The booklet will also tell you all about the amazing new Automatic Finger Control. No cost—no obliga- tion. Sign and send the convenient coupon now. Instruments supplied when needed, cash or credit. U.S. School of Music, 812 Brunswick Bldg., N. Y. C. U. S. School of Music, 812 Brunswick Bldg., New York City. Please send me your free book, ‘“‘Music Lessons in Your Own Home,” with introduction by Dr. Frank Crane, Free Demonstration Lesson and particulars of your easy payment plan. I am interested in the following cuurse: Have You o sswinepaosinee Go seid sseeb Semana Pere MN 6 As 005 5 3.05 544008 40 one cee BIE 6 055.5: 0.3 ix nldscbuiey leans ban eae es oe NP 3:0 ck See ae ee re a SIP a ns = i i | t i‘ Pca rte a eNO ET NAST LLIN ROME EA

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124 You Can’t Beat POPULAR SCIENCE MONTHLY This for Value! Here’s Boice’s newest workshop—the 5-machine Handi-Bench, complete from floor to switch! Designed for industrial or home use. Each machine complete in itself and ready to run. Boice’s Handi-Bench No. § Boice’s Handi-Bench No. 3 As illustrated below, consists of following equipment: Not illustrated. Universal Handi-Saw, 7x10-inch Handi- 12-inch Handi-Band Saw. 7x40-inch Handi-Lathe. 4-inch Handi-Jointer, Universal a ig Saw.

versal Handi-Saw. 2 Motors, double shaft, 1/3 H.P. each. 3x8-foot Bench with legs. Price complete patho. Jin Caw. one 1/3 h.p. double shaft motor and 3x6-foot nch with legs. reer ee $111.85 Note: Any one or more machines in these Handi-Bench outfits may be bought separately at any time. Send 10c for 80-page catalog describing these Handi-Benches an Boice-Crane machines. Ask about our jasy Pay Plan. W. B. & J. E. Boice, Dept. P. §. 12-E, Toledo, Ohio

Sor the Home -Work Shop Manual Training as Gift

With it, Ps ean force door and m. window frames back to theirorig- hi h position and avoid having g sash or doors planedorlocks reset. when You can raise the end of a radia- tor, kitchen sink, ice box or piano closed —or clamp or straighten glued furniture, drawers, radio cabi- nets, and hundreds of other jobs. It’s called © “JACK: IN-THE-BOX” For the man who uses tools, or in train-

tisfied. ly & Co. Templeton. Ken 11. USA. ESTABLISHED 1899 1020 So. Central Av. Chicago - 2 id pias Biiatnture duck seis con's a Gentil t? & d 35centseach for my friends. ee ; eoocee iS On '/: Simplex 30 ak ae are

A City——__—____ State —_____—_ Mark color desired: Red, Blue, Green Check here if you would like to bicaeee | got si plex Jacks

~ an tee © ae Lifetime of ~%i Rich Wholesome Jo Unt you learn to lay, you have no idea of the rich joy, the vibrant fun, the big money that lie in the creation of music. And until you actually try out the peagan Xylorimba in your own home, you have no idea how easy this fascinating instrument is to play! Just think! No tiresome practice. No finger or lip exercises. No teacher. On the first day you play sim- ple melodies. Soon you thrill friends and family with snappy fox trots, dreamy waltzes, Before you realize it, you are ready to appear in public. Xylorimbists are always in demand. The pep of any party, the spice of any band or orchestra. $5 to $25 for a night of “play!” BIG BOOK FREE—Deagan Xylorimbas are sold on a 5-day FREE TRIAL basis. Models to suit every pocketbook. Surprisingly easy terms. You owe it to yourself to write today for the BiG FREE Book. No cost or obligation. Simply fill in and mail the coupon. J.C. Deagan, Inc., Dept. 1659 , 1770 Berteau Ave., Chicago Please send me full details of the Five-Day Trial offer and easy payment plan of the Deagan Xylorimba.

Name

Address

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

$150 TO $300 MONTHLY PROFIT Pays For Itself Without Expense To You

HB 8-Hour Battery Charger insures big year round profits. Charges batteries in % the time required by others. Starts you in best paying business in auto- mobile field. Requires no special expense, uses small space. 30 Day Trial at our risk under absolute money back guarantee. Write today without obligation to Hobart Brothers Co., Box P129, Troy, Ohio. DECEMBER, 1929

| Safety Cover for

| be determined by the installation. To the

| height.—JAmEs H. SuDDETH.

Circular Saw COVER a circular saw that is not provided with a commercial guard, it is possible to construct a convenient de- vice for shielding the blade as shown in the accompanying illustrations. From a 1-in. board, saw out a piece re- sembling the part marked B in the dia- gram. The size will depend upon the saw for which it is to be used. A 3%-in. groove deep enough to accommodate the saw

A circular saw is a danger- ous tool unless guarded.

— iy should be cut in the board in the shape of a semicircle. A 1 by 1 in. rod A should be fastened to this piece as shown. For the half-pulley C prepare a semi- circle of 1 in. thick wood with a 5-in. radius and on the edge cut out a groove for a small rope. Then attach this piece to a pipe or rod, the length of which will other end of the rod attach the arm and guard (A and B). A rope is secured to C, and a weight is attached to the end of the rope so that the protector will swing up out of the way by itself when once it has been lifted about halfway. A stop of some type may be arranged to check the movement of the guard when it is raised to the proper BLOCK quickly and inex- pensively, provid- ed an impression of them has been preserved in a block of annealed steel. This master block is hardened and the stock for the new punches is driven into the depressions. Each punch requires only a little touching up before it is ready to be hardened, and tempered, and put to use. |

PUNCH MADE Ll FROM BLOCK The punch is driven into the steel master block.

©) This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. ————S}|S« a

a

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9

DECEMBER, 1929

Home Workshop Chemistry Simple Formulas that Will Save Time and Money

as time goes on, so that those of us who are fortunate enough to possess ivory objects should take care to keep them beautiful by periodic restoration of the natural tint. Objects cut from ivory that have be- come discolored can be restored to their original condition of beauty by any one of the three methods to be described. All ivory has the tendency to turn yel- low or even brown—either as the result of age and exposure to oxidizing influ- ences, like heirlooms in the form of delicate carvings; or in much shorter [se is becoming scarcer and scarcer time, through contact with greasy or perspiring hands and immersion in hot,

The ivory to be bleached is placed in a wide- mouthed bottle containing oil of turpentine. greasy dishwater, the almost invariable fate of knife and fork handles. One method, which may be applied to nearly all ivory objects excepting piano keys, has been tried out with great success in many art museums. The ivory objects to be bleached are placed in a wide- mouthed glass jar and oil of turpentine poured into the jar so as to cover all of knives, forks, and umbrella sticks, nor the wooden parts of canes. Care must be taken that the oil of turpentine does not penetrate to and dissolve the cement, which holds the tang of the knife or fork in the handle, and usually consists of a mixture of pitch or some resin and brick dust. covered with a bladder membrane and the whole container exposed to the sun- light for from one to two weeks. for knife and fork handles, umbrella han- dles, and similar ivory objects, is to im- merse them in a mixture of one part of peroxide of hydrogen and two parts of water for from one half to one hour, if necessary even longer, until the ivory is

sufficiently bleached. Then polish them

the ivory, but not the metal parts of |

Another method, particularly suitable | — The mouth of the jar should be |

POPULAR SCIENCE MONTHLY 125 HAVE YOU SEEN THE NEW GOODELL-PRAIT ELECTRIC DRILL No. 1051?

Lisr Price $3622 -\Whole Machine Shop on Your Work Bench! No. 125 Bench Lathe with attachments shown offers complete machine shop facilities for the home workshop or laboratory. Not a toy, but a real, husky accurately built ma- chine tool at a price within reach of the aver- age pocketbook. Order from your dealer or write GOODELL-PRATT COMPANY GREENFIELD, MASS., U.S. A. CHICAGO OFFICE,"38 No. Clinton St. a GOODELL- PRATT 1500 GOOD TOOLS NEW YORK OFFICE 107 Lafayette St. LONDON OFFICE, 127 Queen Victoria St.

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

NEW MODEL SOUTH BEND LATHES

Z FOR THE 7 Manufacturing Plant Service Slectric Shep. oun ral Rep Sho Engineering Shop P Machine Shop and nog All on Easy Payments : We ship any South Bend Lathe immedi- ately upon receipt of only 20 per cent of Catalog price. Balance in 12 equal monthly payments. Write for Time Payment Catalog.

9-in. x 3-ft.Junior Back Geared Screw Cutting | Mi | New Free shows all ei Fos Bench Lathe, with "| from 9 inch to 18 inch ae oe Countershaft Driven Lathes, ~ Countershaft *169 Motor Driven Lathes, Quick ©, 5 and Equipment Change Gear Lathes,Stand-_ Kee a . Re Sa Pe) & ater Mang Prices of Popular Sizes of Quick Ciliies Gear ped Bed Lathes, Brake, as : t *S: & Lathes with Equipment Se ae ott $ Size of Lathe Shipping Countershaft Silent Chain ° cee : Weight Drive Motor Drive a <<. os) 9 x3’ 490 Ibs $294.00 $398.00 ng fo* 11” x4’ 725 ibs 359.00 498.00 ae 13” x 5’ 1110 ibs, 443 602 oss 15” x 6" 1550 Ibs 543.00 720 9 v0.08 16” x 8’ 2035 Ibs. 638.00 817.00 oS f y. ‘. WRITE FOR FREE CATALOG SOUTH BEND LATHE WORKS 829 E. Madison Street, South Bend, Indiana,U.S.A. Lathe Builders for 23 years—44,000 users © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

SUR SLT AE Scart rete

Page 128

126 BethelomBrown nya Cytt¢

E ‘one has of Tom Brown, leader of the famous Tom Brown’s Clown Band, one of the highest priced musical acts, that has ap- peared all over the world. Pgs have not seen them, you have prob- y heard them play on Victor Records. First-Class Saxophonists make big money and the work is easy and pleasant. You might easily become a wizard like Tom Brown, or a great record- maker like Clyde or Bennie Krueger or Joseph Smith. $100 to $500 weekly is not unusual for such musicians to earn. Ba. True Tone Saxophone The many patented improvements, found only on the Buescher, assure a more beau- tiful tone, finer and more

blowing qualities. Easy to Play— Easy to Pay Because of its many advan- _ the Buescher Saxo- phone is remarkably easy to master. The rapid prog- ress you make will surprise you. Easy payments can be eeranged. if desired. 6 Days’ Trial in your own home on any Buescher Saxophone, Cornet, Trumpet, Trombone or other instrument. Fill out and mail coupon for full infor- mation. Mention instrument in which you are interested. Buescher Band Instrument Co. 2950 Buescher Block Elkhart, Indiana accurate tune and easier | POPULAR SCIENCE MONTHLY

by briskly rubbing with a woolen cloth. If the ivory has become yellow through handling or contact with dishwater, it is advisable to begin by immersing in alcohol, gasoline, or carbon tetrachloride, and after drying, rub vigorously with a rag dipped in 3 percent peroxide of hydrogen or a 5-10 percent solution of citric acid. After the bleaching is com- pleted, the ivory should be rinsed with clean water and then rubbed dry. If the ivory forms the handles of knives or forks, care should be taken to protect the metal parts by coating them with vaseline and then wrapping them with paper to prevent the grease from spread- ing. If necessary, this process can be repeated two or three times. The white- ness of piano keys can also be restored by this process.—E. WELLECK.

Laundry Case with Removable Bag HE case illustrated, aside from being an attractive receptacle for soiled linen, has the added advan- tage of being so constructed that the full, heavy laundry bag can be removed easily

SUESCHER BAND INSTRUMENT CO. (Ht | ' 560 Buescher Block, Elkhart, Ind. i | 8 Gentlemen: Withevtebiigating me | in any way please send | § me your free literature. . 1 I am interested in the { ; following instrument ........cccccccccccccccccess t . ' Di icdcnetandr Shaaneehanoonesévecneescenes ry t De Bere a as ns inate aie tab Sad a} in in'ain ‘ne Sab es i inane ed

ip ownership and wane —p— or full-time PROF. ATS! Write for FREE peste Bios Fay Ofer AMERICAN CHIME ¢ CLOCK C MPANY 1691-F Ruffner St. Puilegsiohee, Pa.

By removing the front, the tied bag can be easily taken out and an empty one hung in place. by taking out the front of the holder. No heavy lifting is necessary. For the family that is now stowing its soiled linen and clothing wherever it will best be out of sight, this case would be a much appreciated addition to the house furnishings. The sides may be made of i in. boards glued to give the required sizes; but to avoid danger of warping and split- ting and to insure strength, we will as- sume that %-in. plywood will be used. Cut the back and the front 18% in. wide, the two ends 11 in. wide, and all 29% in. long. These widths will allow the pieces to be cut from plywood 30 in. wide, which is a stock size. Make two cleats A, % by 1% by 9% in. and three cleats B, B-1, and B-2, % by 1% by 17%

DECEMBER, 1929 x. —H ET. co. is Dept.c.s71 108 N. State Street Chicago, til. DIAMONDS WATCHES

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Model Aiplene Reske Manual of Model Airplanes, ABC of Model Airplanes, Model Airplanes and Flying Boats, $1.00 each, three for $2.50. Each book fully illustrated, written by noted authority on Model Airplanes. Price List Parts and Blueprints, 5 cents Order Now, Model Airplane Book Publish- ers, 29 East Avenue, West Haven, Conn.

(Ob e w-\% 7-e hele y-\ a4

from factory or nearest of 4 branch OTTAWA MFG. CO. 1801 -W Wood Street, Ottawa, Kansas

For Xmas—Make Your Bey (or Your- self) Happy With the H & A LATHE Sturdy, well bal- anced, splendidly © acurate—a truly wonderful machine at surprisingly low cost. A gift that will delight expert or novice. Prompt shipment. Write A. @ — for catalog. HESTON & ANDERSON °2,Macist street

GEARS In stock—immediate delivery Gears, speed reduce sprockets, thrust bearings, flexible couplings. Pulleys, ete. A complete line is carried in our Chicago stock. Can also quote on special gears of any kind. Send us your blue-prints and inquiries. Write for Catalog No, 214, Chicago Stock Gear Works, 769-773 W. Jackson Blvd., Chicago, Ill.

A definite program for getting ahead financially will be found on page four of this issue. @ This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

Page 129

DeEcEMBER, 1929 34-in. holes for dowels in cleat B-2 and fasten all cleats with glue and brads. Bore 1-in. ventilating holes as indicated in all sides. Make the bottom % by 11 by 1734 in. and the top % by 134 by 20% in. Fit and glue pointed 3-in. dowels in B-2 and bore holes in the front of the bottom to receive them. Assemble with brads through the back and ends into the bottom and with will not hold so well. Fit the front in place. Make or buy four flat brass hooks | D and fit in place with %-in. No. 10 roundhead screws, filing their points off where they come through the ends. Hang the top with 2 by 1% in. butts (hinges) as at 2in side view. Fit and glue a 3-in. pointed dowel in cleat A of each end and bore a corresponding hole nearly through the top to hold the top front corner of the ends in place when the front is down. i 7 ; : - 2” 7" wl ep 6 -ehe~ 6 Fase | 4 HOOKS D BOTTOM. the. amen ed femme es oe eae oe ge ew ae ane + 4 4 i. men perl ay + a a x theD we OA °. 4 © 0 90 Oo = of °09o 0 0 | 0 oO ° ° I 3 : | | B-1 | I { —. sess bp “ie *5 y » | ° ° 0°00 0 | ° ee 0 © 4) ©.0 | } + lee re) ’ oO Se meen ~ “js ib °% © - FRONT VIEW SIDE VIEW * A 5B B B-! u : B2. ENDS TRACK wt 18%4X29% Ai 29% | : ux 20% ; REDUCED SCALE Accombly drawing of the case pend details of the construction of the front, the back, and sides. Prepare two cloth laundry bags that will fit the case loosely, making them about 1 yd. high to allow for a draw string in the top edge. When a filled bag is sent away, an empty one may be put in its place. To remove the bag, tie the draw string, close the cover, raise hooks D, draw the top of the front forward, lift the dowels in B-2 out of their holes, and pull the bag out through the front. Re- place the front, lift the cover, and put in the empty bag. Hooks placed at EZ and corresponding rings or loops on the out- side of the bag will be convenient in keeping the bag open. Pieces of tape or wide rubber bands fastened to the inside of the cover to hold laundry lists will constantly remind each one to record daily deposits. The case may be painted or lacquered in attractive colors. Four casters or pol- ished steel glides may be placed in the bottom to move the case about. screws through the back, for brads alone in. and bevel them % in. as shown. Bore | POPULAR SCIENCE MONTHLY _AIR=CON 127 —the King of them all A Workshop You Don’t Need to Coddle A workshop that won’t do all that you want it to do is, after all, only an ex- pensive plaything. Make sure before you buy that the outfit you choose has the power to handle any load within its capacity; and the rigidity, strength and precision construction essential to fast and accurate workmanship. Then your choice unquestionably will be the Ar-Con Utilitool—the workshop that means satisfaction with every job you do. Free Trial! Easy Terms! Mail the coupon now for fully illustrated descriptive circular, together with details of our 10-day free trial offer and liberal time payments applying to the complete outfit or any unit or combination of units you may desire. THE AR-CON TOOL CO. TOLEDO, OHIO pw Ar-Con Tool Co. 500 Fassett St., Toledo, Ohio 8. | Mail me complete information, prices and terms on Ar-Con Utilitool with details of your free trial offer. ee eeeeseeeeeeee ae Join =— MODE CLINTON JUNIOR AVIATORS MODEL BUILDERS—If you really want to learn how to build all types of model airplanes, here is the reatest proposition ever offered. Join the Clinton Funlor Aviators. The total membership cost to you is _ Dollar ($1.00) a year, and this is what we send a: 2 ” Twelve plans (regular ane 25c each, $3.00 total ue) e each month for 12 months—each plan different, ne advanced in design, with full Instrostions for miaking and fi ying. ‘e also en- close a news sheet with valuable information for model builders, mippares. instructions, news. 2. A year’s members! card—entitling you to full club privileges and the prize opportunities offered in regular bulletins. 3. A Discount Sheet with 12 coupons, good foe for 10% Gietount on on all material and parts p hased thru the 4. Monshiy pritca of $5 to $100 for the best models, poss ights, “e hhotos and news, securing new mem- bers, ete. Under this club plan you can build more and better models at great savings in cost. Can you imagine any greater value or any similar plan at any price that helps you to really study Aviation, Send in your memberhip right now and receive by return mail Plan No. 1—Junior Aviator Special Duration Scale Model. one of the under this neatest designs ever offered. Easy to construct* Club Plan 20” wing, built-up, 14” fuselage. Stays in the air for a minute and a half or more. Fine for fiyin either iin or outdoors. Very light—weighs less than 1 oz, plane is a wonder—you will rave about Senior Aviator and de- sen of pope model aircraft for over ears, invites you to join with thousands of other boys whom he has helped nstruct. SPECIAL COUPON ie fill in ths coupon below—enclose $1. 00 (check, bill or money order) and eee the rest. Let's get off to a flying Clinton Junior Aviators, ¢/o Clinton Tex Cor orth Haven, Conn., Pept. Kl. Dear Mr. Clinton: I sure want to join your Junior Aviators ub. Here is my dollar. Put me down for a_year's membership and rush me Plan No. 1 at once! G=t ‘these points about the new Paint-O-Mister—A one-piece Gun with pistol-style grip. Finger rest—hand rest. Two-finger easy-pulling trig- ger. Air Valve with porthole to by-pass air when not spraying and motor is running. Hook to hang gun when not spraying. Spray volume regulating valve —One fluid jet for all mate- rials. Lock ring keeps air nozzle in position—prevents air leak- age. Two air nozzles furnished —for round and flat spray. Compression stipplies 25-30 Ibs. pressure. Plugs into any light socket. Portable—paint container weighs 1% Ibs.— compressing unit 5% Ibs. $3Q52 complete. The Atomister Corporation, 42 Hamilton Street, Rahway, N. J. At your dealer’s —or from us @ This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8. | | | f E I }

Page 130

128 POPULAR SCIENCE MONTHLY DECEMBER, 1929 UNDERWOO elow 22 Pric

— if

Toaster made from an aluminum pan, asbestos, wire mesh, resistance wire, and small fittings. ’ / Simplified Electric v ! tn CMU, Who?

. Th druggist. EASY ; Toaster Built De. aaa . ’ A dime. _at Low Cost Why? For a cake of Lava Soap that’ll get the HIS inexpensive electric toaster was grimiest hands clean in 58 seconds. You can Row ° , see the pulverized Italian pumice in Lava Ss 4 d rd designed by E. A. Rerucha, of Wake- Soap drag out the dirt, but you can’t fee/ it, tanda field, Mich., and won second prize in the Lava makes a rich, creamy, penetrating Keyboard | electrical division of a national shop lather in the hardest water. But it won’t harm your skin. It’s the busiest hand cleaner you’ve ever tried.

problem competition for teachers con- ducted by the Educational Department of PoPpULAR SCIENCE MONTHLY. The base of the toaster is made from Gangs, Ue faveSoop Mam an aluminum pan of the type that can Sent loXou; for Only

be bought in any hardware store. The — —_ oe eS 4 wie Bt par spaentein the raving 0y Bins | Set yates maton meatlly saymees peer Me er ca ae y 8g Procter & Gamble, Dept. X-1229 rd "Underwood with 4-row keybourd that are fairly constant. Cincinnati, Ohio a The legs are cut from No. 14 or No. 16 George: I want a free sample cake of Famous No. 4 Underwood gage sheet aluminum and are bent into your Lava Soap. Jay sa dees earn hee oa shape on the dotted lines shown on the gcc chify look ont me ny other, improvements. Beautifully refinished and pattern drawing. They can be fastened Street. . oh sa caalc aaeis a aeiek to the bottom of the pan with small City |

FREE! FREE!| 1° Day FREE Trial | tinner’s rivets or by using No. 4-24 ma- Complete (Home Study) Send coupon for 10 day Free Trial— ° Course of the Famous Van 9 if you decide to keep it pay only $3 | Chine screws and nuts.

Sant Speed Typewritin - . ‘ nly ° . Symen—tulty Slustrated. | 81°50 (term prin) io peld. Limited The heating element is made from 18

cHer—aet at once. ft. of No. 25 nichrome resistance wire, Other Sensational Bargains! coiled by winding it around No. 12 iron

ay LC. Siaith Sion, Mate Cogh Higw Only $08. wire. This coil is mounted on asbestos ies Woodstock $100. oe eo @ °° @ slate )% in. thick, as shown. Two binding screws are placed at each end for use in

INTERNATIONAL TYPEWRITER EXCHANGE, 231 West Monroe St., Chicago, I!., Dept. 1238. osepes fie 4 Vedawesd eeeee-No. 8 L. C. Smith asedne I .....-No. 5 Woodstock Send ty pew iter chee ed above for 10 days Free Trial. I am _ en- closing $1 deposit with as that it will be returned if the typewriter s not = f Tkeep it I will pay $3 a month until $44.90 [term price] is paid. SIZES AND STYLES MAGNETO EQUIPPED

Also on Iron Base All Fuel—All Purposé—Power

SSSSCESSSCECESeeeew sss Bis oe bSs 60666 cd ccccmttEhseresecesc<cccces tv cccanans 60 years of scientific research to produce and pF : maintain the world’s most reliable, economical a6 soc nipesisbocccdscodooccccocectocescseccccccccscce s source of power for every need of the farm, gf . home, shop or mill—has resulted in this Ltddsidacdnsainadgedindbaasdoocecsceses State.......+s+000 8 wonderful engine. Runs as well on cheap fuels

as gasoline. All parts interchangeable—no costly repairs. Every Witte unit pays divi- dends from the start. Put one to work now! Ask your dealer or write us for catalog. WITTE ENGINE WORKS KANSAS CITY S : *s : Cw a. 7 *~ screws nowine NGINE BUILDERS SINCE 1870 SCREWS HOLDING ELEMENT ON BRACKET iene || PARKS WOODWORKING MACHINES

Guaranteed ten years

: 1 Cabinet Shep i Special No. 10 $290 with Motor ee eee NE | - fee Subeton Boe ou oug ave } — on Write today Tor fa” ow — | a this handy Parks in FREE Beautiful Book of your shop. Compact, A. LIBERTY HOMES = | LEG PATTERN er. ane - f ee ures wo! homes fro x . 81 ike a big production ou a cos hos lath, hardware. paints. nal Kinterals fally GRID oor space required only 42x72 inches. Does any Plans FREE. Freight paid east of PATTERN 6 stacy des * t kind of cabinet or joinery work. Write for circular. Miessning } = Missourt” "Spe (REDUCED SCALE) - The Parks s Woodworking Machine Co. , | 1547 Knowlton St., Cincinnati, Ohio

MFG. CO. "| Assembled toaster and grid and leg patterns. Canadian Factory: 338 Notre Dame East, Montreal a Dept. 1312, Bay City, Mich. 3

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

Page 131

ae DeceMBER, 1929

connecting the attachment cord, which is 5 ft. of No. 16 or No. 14 asbestos- covered heater cord. In attaching the cord, an underwriters knot must be tied next to the bushing. Be careful to leave nection. The grid can be made from No. 21 hardware mesh or cloth. Cut it to shape and bend as indicated. The grid should fit snugly inside the pan top, and the sides when bent down should rest on the asbestos plate. To obtain the best results the position of the grid will have to be determined by trial. To fasten the grid | in place after the proper position has been determined, solder a small nut in the middle of each side of the grid and fasten it to the sides of the pan by means of screws. This description is a condensed version of Mr. Rerucha’s article which, with the contribution. Small Clock Case for Holding a Watch Y SETTING an ordinary watch in this artistic little case made from a single block of mahogany or other hard- wood, an attractive, serviceable traveling or desk clock can be made. The case is 2% in. square and 6 in. long. It is cut out at the top as indicated, so as to leave an ornamental triangle of wood, which conceals the projecting stem of the watch. The dimensions of the slot and hole for the dial must be adapted to the particular watch to be used, al- though the slot should be a trifle large so that it may be lined with soft cloth: Directly through the open- ingforthe dial, drill a hole back into the block about the size of the dial opening and % in. deep, and pack into it some cloth or felt, which will act as a spring and hold the watch firmly in place, tight against the rim. The case can be stained and finished with shellac, clear lacquer, or varnish. In the original model a saturated solu- tion of permanganate of potash was ap- plied, and a red cherry wood stain was then used. After this was dry, several coats of shellac were applied and well rubbed down. A plain inlay of holly or other white wood, if placed as shown, will add to the beauty and decorativeness of the finished product.—SAMUEL GORE.

VELVET,

The case is made from a solid block of wood. A RECTANGULAR piece of ordinary screen wire or wire mesh bent at right angles makes an excellent rack for holding and drying small parts that have been freshly painted.—C. B. W.

enough slack so that there is no strain | transmitted to the binding screw con- drawings shown, formed his prize-winning |

POPULAR SCIENCE MONTHLY the thrill of icill j this modern s0oferized way! The Only down Complete Interchangeable Power Shop tures —Improved Exclusive Fea Now you can do the things you have long wanted to—at home in ycur own modern motorized workshop—witn this new, improved > Waco Red Jacket Wonder-Shop. No other compares with it in complete, interchangeable, power features, efficiency, exclusive Special Craft advanteges and quality. Join the Ha The Waco Guarantee grinding and cleaning. Attaches to light socket. Converts your If it is not what you Work benc’ into a complete private tool and machine shop. Add FREE BI pe Pose a get it— news ial equipment any time as desired. aad it back. void Imitations! Waco Red Jacket is the pioneer— Prints foremost in the field—sold only direct from the factory; Pe not through stores.

You Can Buy NOW on Easy Terms Facts Only $1 down. Easy monthly payments. Libera! discount for cash. No hardship to own a Waco Red Jacket. surprised and fascinated. c y Family of Waco Wonder-Shop Workers Wm. L. Aylward, Waco's president and nationally known crafts- p oer ae Ath here man invites you. He will instruct, guide and help you. The new 1930 Red Jacket Combination brings you the powerful -riais,carving, turning Red Jacket Master Drill Motor, Wood Turning Lathe (capacity sawing, designing, 9 x 36 inches), Compound and 18-inch Rests, Tilting To Atre te. ote., is taught Saw, Sander Disk, Scroll and Jig Saw, Band Saw and all Acces- you by correspond- sories for both portable and stationary power drilling, buffing, énce FREE. FREE! Send This Coupon for inqerey Detailed descriptions. You will be Just see what you can make. Fillin and MAIL * NOW.

urse F methods, raw mate-

WACO TOOL WORKS, Inc. 5216 W. Kinzie Street, Chicago, iil. Manager, Dept. 12. Please send me all free information and literature on Red Jacket Assemblies and FREE Services. BD 3.055.050 dans dnqgunssedcangesscuqepeees ‘ Address as mkt eens ° _ . wr coe Cr RTOs 00 cncgtcenevcdhecinssitecacsabtendosuta

Model 2. Racing Type 24-in. wing spread. .$2.00 ) Miss,

Compete and Win With the “Silver Arrow” Beat the other fellows! With this plane you can confidently get into competition with boys who have other planes, and consistently win the contest. Here’s a plane that flies—flies!!—not just once or sometimes but repeatedly. Fool- proof, trouble proof, it does not disappoint you. More flights, too, because it’s durable—built to stand rough usage. Launches by hand or “‘taxies’’ and ‘“‘takes off’’. Zooms way over the housetops on long continuous flights. Not a construction toy but a fully built plane. A few moments to assemble and it’s ready to fly. Designed by Charles H. Grant, one of the foremost pioneer designers and builders of model airplanes in the United States. That’s the reason! New expert construction. Wings and body of light Balsa wood reinforced with aluminum braces; alumi- num propeller; strong elastic motor. Durable, stable and beautifully ‘‘finished.’’ Three models: No. 1, Racing Type, 18-in. wing spread, $1.00: No. 2, Racing Type, 24-in. wing spread, $2.00: No. 21, Cabin Type, 22-in. wing spread, $2.50. (West of Miss. $1.10, $2.20, $2.75). plane that really flies—all the time. If your dealer hasn’t the Kingsbury thriller, order direct. Kingsbury Mfg. Co., 107M Myrtle St., Keene, N. H.

KINGSBURY Moror DRIVEN Toys Send 10c¢ for this Eraser: “balloon” tire of solid A steel disc wheel from a eraser rubber. Set of four, Kingsbury Toy with a 35c. Toy catalog free.

In Carpenter Shops theyusethe TAKE, Sander

Ore yy want this light, electri- _cally driven tool because it eliminates tedious hand sanding and finishes doors, cabinets, sash and similar jobs 5 times faster. Concerns —— in aviation, building con- struction, woodworking, metal working and many other manufacturers, schools, etc., also use the TAKE-ABOUT Sander for their particular sanding, finishing and scraping operations. On metal or wood surfaces— glass-like finish is as- sured, due to rapid belt action (1300 ft.

p.m.). . Just plug into any light socket. Car- it to any job. "Pelt does the work. You sim- ply guide it and save 80 cents out of every

<— . —— sanding dollar. Where there was hand sanding, Write for all now there’s a TAKE-ABOUT the facts. THE PORTER-CABLE MACHINE CO. 2000 No. Salina St., Syracuse, N. Y. PORT|/-[ABLE © This sealon an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

Sin trae eer

Page 132

139 POPULAR SCIENCE MONTHLY DEcEMBER, 1929 #—=PIN A DOLLAR BILL TO THIS= Hints on Handling Get this genuine - vp ‘ leather 5 window pits So sgt a Paint Brush a or other stam- ping 35c extra, per line. Money back guarantee. 9 windows $1.50. 13 windows $2.00. A Novel Charm \y A most mysterious watch charm of hea plated gold. Shows the Square and Compass when revolved. Something different. Packed in an attractive box. Catalog suggests $400 many other gifts 1 Sk ‘lf ll sonic dy . em Stamped in heavy 1 u y gold. Your name SOLID GOLD PIN Just the right size. Latest style. A lasting re- membrance and an appreciated _ pres- ent. Large variety—Ma- Please send catalogue sonic, ( hapter, = : 32nd = Degree, [_] No. 10, Books, Monitors, Shrine, Grote: Jewelry : O. E.'S., De [] No. 11, Lodge Supplies Molay. $1 00 Established 1859 ~~ ......... Redding Masonic Supply Co. 200 Fifth Ave. - Dept. P. S., New York Riosiens *‘ Everything Masonic’”’ ¥ AEROVSX BUILT BETTER “CONDENSERS AND RESISTORS This printed INSURANCE CERTIFICATE guarantees every TRIAD Tube for a minimum of six months’ | perfect service ora properad- | | justment made! You will Use a paint brush with a moderate, even pres- | Without a Doubt find one in every TRI AD | sure keeping the hand directly over the brush. | The Most Complete Line oF carton—and you can trust KILLFUL handling of a brush and | Consensess & yeaa’ TRIADS to live up to it. In | thorough brushing-in of the paint- | |} in ‘the fued condenser of vesistor field. you actual number of service | ing materials are the fundamentals afe sure to find an AEROVOX. unit exactly hours—in volume—in qual- | of ee the ——— cond you cur complete catalog on soquett. . give close attention, because they largely ity of tone—TRIAD Tubes ] | determine the success of ‘the work; pro- are unsurpassed. There are | vided, of course, that high-grade paint © longer, happier hours of jf | and first-class brushes are being used. at 7 trouble-free radio enjoy- : To hold and use a paint brush improp- \ ail ment in storefor you with | = oo = em yee - = ’ Your name will be put on the mailing list a | or damages the shape. Generally speaking, free of charge on request. TRIADS. Get them from | | 2 brush should be held lightly and firmly your nearest TRIAD dealer 1 | with the narrow part of the handle be- | —without delay! They im- | | tween the thumb and the first two fingers, | rove any set! ] | much as a pencil is held in drawing lines P y | with a rule. It should be used in such a way that it wears down uniformly and Tune in on the TRIADORS every | | keeps its original shape. Do not grip a Friday evening 8 to 8:30 (Eastern ] | brush by the stock with the thumb or BRINGS YOU THIS SAW Standard Time) over WJZ and | | fingers extending over the bristles, and COMPLETE MOTORIZED cussteted HBC Stations. ] | do not bear down too hard on it. GUARANTEED 22,2475;, | Use a moderate, even pressure in ; i | spreading the paint, and a light, even ] | pressure in finishing. The muscles of the wrist, which do most of the work, can be relieved by those of the shoulder. 8" Saw with % H. P. Motor —shipped to you onapprov- al for only $5.00. 10 Days’ Free Trial. Then convenient monthly termsif you keepit. Send for complete facts on “Askfor the 1| While the brush is being drawn back Circiar and Sg Saws Folate tube in the é | and forth across the surface, do not let the = CORPORATION blackand 1 &§ a 1 | hand lead, but keep it directly over the ee 225 N. Michigan Avenue yellow tri- ; LZ brush. Lift the brush from the surface angular « Raai before starting a return stroke. Poking or box.”” ‘Selo, jabbing the brush into corners or cracks breaks off the valuable flag or split ends and ruins the bristles. The flag ends are what makes a brush | | valuable. One unfailing test used by | | practically all professional painters in TRIAD MFG. COo., INC., | judging the quality of bristle in a brush > > > > > > > » » > > > » U » , > » ‘ ; + Hf s wing spres ” wi in fusela > Tea woou ller Pawtucket. R. I is to spread the bristle stock into a fan | fsi,"rbier*motor. “Soar to erent helahte,” Completely, amembled: e . bs ° m asten Wings a unch. 2 . Guarana ve 4 9 shape, hold it up to the light, and look Pare Pare rubber. 1 78" flat. 1/2¢ foot; 2/16” flat le foot. Postage all rders 5c extra. SPEEDO MFG. CO., Dept. s, ‘200 Albany Ave., Brooklyn, N. ¥. @ This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

Page 133

DeceMBER, 1929 a AUDIO TRANSFORMERS Worthy of the HAMMARLUND Name Plate [pESIGNED primarily for the new “HiQ-30”’ Custom-Built Receiver, Hammarlund Trans- formers are a revelation in amplifying power and tone fidelity over the entire audible frequency range. The large cross-section core of specially treat- ed laminations permits high primary currents without saturation. Completely shielded. Pig- tail terminal leads for sub-panel connection. Four types:—First stage, Push-Pull Input, Push-Pull Output for magnetic speakers, Push- Pull Output for dynamic speakers. Hear them! Try them! They will greatly improve the output from any circuit. Write Dept. PS12 for Details HAMMARLUND MFG. CO. 424-438 W. 33rd St., New York Jor Better Radic ammarlund PRECISION PRODUCTS Advice for POPULAR SCIENCE MONTHLY readers regarding safe and profitable investments. See Page 4. Longer Life —_ Higher Efficiency Shock-A bsorbing Sockets Lessens the possibility of short circuiting the elements of the tube. Heavy spring contacts provide excess cur- rent carrying capacity. Special side wiping contacts assure posi- tive tube to terminal connections. Bronze suspension ring, contacts and sol- dering terminal all in one piece. Terminals plainly marked. For direct attachment to panel... $ .75 For mounting on top of panel.... . 1.00 At all Radio Dealers Manufactured by Benjamin Electric Mfg. Co. Des Plaines, III. New York Chicago San Francisco POPULAR SCIENCE MONTHLY for the flag ends on individual bristles. The professional knows that only a good brush has these valuable flag ends. When a fine Chinese hog bristle paint brush has these flag ends, it is an ideal tool for brushing, but the amateur must use it properly so as to accomplish six results, as follows: Penetration. Work the paint thoroughly into every fissure and crevice. Let the flags dig down into the surface, securing deep penetration of the painting material. Surface Moisture. Every surface has a certain amount of surface moisture that must be thoroughly rubbed out. Surface Tension. Because of contrac- tion and expansion caused by changes in temperature, there is always a certain amount of surface tension. The strokes of a good bristle brush relieve this and the finishing material does not crack or wrinkle. Air Bubbles. These must be thoroughly brushed out if a smooth, mirror- like surface is to be obtained. Coverage. Only when the brush digs down into the pores of a surface —not merely slides across it—can proper coverage be obtained. Adhesion. When well brushed, the paint becomes an integral part of the surface itself— not merely a “paint film” which will eventually crack and peel off. The professional painter knows from experience that paint materials will pro- duce a better surface and last longer when thoroughly rubbed into the surface. This applies to everything but lacquer, which should be flowed on the surface with a very full brush. Lacquer should never be backstroked or leveled off. Too thick paint, varnish, or other ma- terials will not harden properly and will tend to leave blisters instead of a smooth, glossy surface. Paint must thoroughly wet the surface to which it is applied, and the combined thickness of all coats should be just sufficient to harden and protect the surface. Experience quickly points out the fatal mistake of attempting to paint with a brush that is not of good quality, abso- lutely clean, and the right size. The question therefore arises as to how to select a good brush. Paint brushes are of such a nature that they can be easily “doped”; that is, the mixture of bristle stock used may be blended with various adulterants, such as horsehair or vege- table fiber. The average person, when selecting a paint brush, will rely upon the recommendations of a dependable hard- ware or paint store. When a painter is selecting a paint or varnish brush, he bends the bristle stock over the back of his hand to judge the flexibility of the brush and whether the bristles are springy and full of natural “oily life,” as they should be. Next, he considers the length of the bristle stock, FLAG OR SPLIT END OF BRISTLE FLESH OR ROOT END OF BRISTLE The bristles of a good brush have flag ends. 131 United States Government APPROVED SCHOOL for Transport-Limited Commercial Private Pilot & Ground Course There is money for you in aviation if you get thorough training now! Our courses will give you this training—they are taught under the direction of U. S. licensed transport pilots and mechanics and cover everything about — motors, their maintenance and con- struction. The training which the stud- ent receives at the School of Von Hoff- mann is the exact training which he must have to qualify for immediate positions on the ground or in the air. Our equipment is new and of modern design, subject to 7! U. S. Gov't. inspection—the cost is low considering actual flying and the thoroughness of ground instruction on latest modern type planes, Wright Whirlwind and other standard motors. bond required. No student World’s Famous Pilots Trained Here Our field is identified in the world of Aviation as an outstanding place to enjoy the best training,—a place where conditions are ideal—from here was started the ’cross the Atlantic Flight that convinced the world what could be done and more recently the world en- — flight record was established ere. Easy Monthly Payments It iseasy to pay the Von Hoffmann way because small monthly payments are extended. Let us show you how you can start now and pay later, even after you have finished the course of training. VON HOFFMANN AIRCRAFT SCHOOL 824 Lambert-St. Louis Flying Field ST. LOUIS, MO. VON HOFFMANN AIRCRAFT SCHOOL 824 Lambert-St. Louis Flying Field ST. LOUIS, MO.—MAIL TODAY TRAMEG 5 6 5.0.0 si06 60:0. 9.0.0.00:00.05:00666060 60068 EGCR0S SO BGBTORS . . ods ccrcvcccccccscccascccc ss cetesinccs CY .ccccccccvcccccssescvecees BEACO. 200 ccccece Co NRA ee I am interested in (] FLYING COURSE (] GROUND COURSE. © This seal on an advertisement in POPULAR SCIENCE MONTHLY signifies the approval of the INSTITUTE OF STANDARDS. See page 8.

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132 POPULAR SCIENCE MONTHLY DECEMBER, 1929

Let a set of new Cun- ningham Radio Tubes flood your home with harmony this happy Christmas season. E. T. CUNNINGHAM, INC. New York Chicago San Francisco Dallas Atlanta +48. Be-

tance | aan The Safest Resistance | For Your Eliminator be sure of [TRUVOLTS—2n8 best. They last longer, are accurate y rated and are conv en ient to mount. TRUVOLT All-Wire Resistances Use - uSTAB 9 SUDING CLP

‘ tion .cooled construr stands up under load and ieust- Sliding clip permits de cired. N ment to exact value o - bles—with OLT_ Variabeeeonven= justment- Patented air

ee of tact over resist- a travel of oes weare st | sizes, $2.50 each-___.... saercsenenenn ELECT’ INC., 12 BET se New York, N. ¥. — ane r T, Resistance " TRUVOLT, * sae eevee? SEED asenncososseeene eee set Address ..-s0000"""""* se nora <a

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

for that is one of the primary differences between a cheap brush and a good quality brush. The greater the amount of bristle stock, the more painting material it will hold and spread without redipping in the paint can. Bristles make up, by far, the biggest single item in the cost of brushes, for the bristles alone cost anywhere from two to fifteen times the cost of the next largest component of which the brush is made. Bristles used in cheap brushes are usually left-overs after the best grades have been selected for the better brushes. Next to the bristles, the most important construction feature of a brush is its set- ting. This is the trickiest feature of a brush to judge, and even a professional painter depends upon the judgment of the paint dealer or the reliability of a | brush manufacturer.— R. E. ALEXANDER. New Colored Pencils Aid in Ship Model Work R applying delicate decorations on ship models, for coloring flags, pen- nants, shields, and various ornaments, and for marking out minute panels, windows, and doors, a new type of colored indelible pencil can be used with far greater ease than a paint brush. The pencils, which are made in twelve colors including black, have thin leads so that they can be sharpened to fine points and used like ordinary drawing pencils. They make possible the drawing of the finest lines and the most elaborate orna- ments. When the decorations have been applied and shaded as desired, a fine camel’s-hair or red sable brush is dipped in water and used to blend the individual pencil strokes together wherever necessary, giving the effect of exceedingly clear and delicate painting. On woodwork and metal parts it is necessary, of course, to apply a ground coat of flat white, light gray, or light brown paint as a foundation for receiving the colored ornamentation. On cloth flags the pencils are used without any preparation, and no further treatment with water is necessary, as the strokes blend together very well; on paper flags and pennants, however, the brush and water treatment is necessary. Any surfaces decorated in this way can be given a protective coating, if desired, by spraying on very thin shellac or artists’ fixative. It is possible even to brush on a coat of thin shellac without disturbing the colors if a very soft brush is used and the work is done very quickly.—L. T. G. Caring for an Oilstone KEEP an oilstone in condition, use a good grade of mineral oil, wipe the stone off when you are through with it, and keep it in its case or at least in a place where it will be free from dirt. The surface of a worn oilstone may be dressed to a plane surface on the side of a grindstone, or it may be rubbed down with an emery brick. Another method is to tack a sheet of emery cloth to the bench-top and rub the stone back and forth upon the cloth, stopping now and then to clean the dust from the cloth.

Full of PRACTICAL RADIO DATA For the CUSTOM - BUILDER and ADVANCED FAN Describes the newest and finest BAND-FILTER TUNING SYS. TEM—SCREEN-GRID AMPLI- FIER—PUSH-PULL AUDIO AM.- PLIFIER—POWER PACK— UNIT CONSTRUCTIONSYSTEM —EFFECTIVE SHIELDING —SPEAKERS— CABINETS— IN- STALLATION—SERVICING. It will make money for you; it will save money for you.

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30 DAYS FREE TRIAL’ \ w LOW PRICE Ww EASY PAY- ¢ MENT ( CAMPBELL’S Electric Exerciser BUILDING THE BLUENOSE MODEL SHIPS We can also supply construction sets and all sorts of parts such as semi-finished hulls, blocks, dead- eyes, special flags, anchors, steering . wheels, capstans, figureheads, blue prints, books, etc., for building models of the Bluenose, Fl Cloud, Constitution, Spanis Galleon, Mississippi River Steam- boat, Sovere of the Seas, Half Moon, ayflower and many others. Also special construction sets for racing sail boats, power boats, model steam engines, propellers, etc., and fine tools for the model . Our large 48-page photographically illus- trated booklet contains valuable information and hints for building ship models in addition to prices and full description of the above articles. any people only slightly interested in models have be- come greatly enthused upon receiving this booklet. Be sure to send for this booklet before starting your model, as we can save you considerable time and money. copy will be sent postpaid upon receipt of 15 cts. (coin preferred Model Ship Supply Co., Dept. P, Mineola, N. Y.

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

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DeceEMBER, 1929 POPULAR SCIENCE MONTHLY 133 Step Out of That Low Pay No Future Job In I2 Weeks Don’t let added responsibilities or old age find you being kicked around from one job to an- other—never sure of a steady job and willing toworkatany old pricethey wanttopay you. eT Into ELECTRICITY My Amazingly Easy Way Right now— Today — decide once and for all to get out of that small pay, hopeless job. Now— and forever—say good-bye to twenty-five and thirty-five dollars a week. Let me show you how to qualify for real money-making jobs LEADING TO SALARIES OF FIFTY AND SIXTY DOLLARS A WEEK AND UP, in Electricity—NOT by correspondence, but by an amazing way to teach that makes you A PRACTICAL EXPERT IN 90 DAYS. Getting into Electricity is far easier than you imagine. Learn By Doing In 90 Days Right Here In the Great Coyne Shops Without Books or Lessons Our Student Service Department Handles All Your Problems You have nothing to worry about. My stu- dent service department takes care of get- ting you in a good clean home where you will get room and board very reasonable. You will among friends here at Coyne whosee that you are made comfortable and happy while you are with us. Good clean sports and enter- tainment are — during hours when you are not attending school. Aviation Electricity, Radio and Automobile Electrical Courses as wellas Railroad Fare included Right now I am including all the above at no extra cost, and I’m offering my course for a short time at a special reduced price. Coyne has had an unusually suc- You don’t need advanced education or any former electrical experience here at Coyne. I don’t care if you don’t know a generator from an airbrake —I don’t expect you to! Mail the coupon today for my big Free Book. It tells you how I have taken thousands of fellows just like you out of small pay, man- killing jobs and made them happy and con- tented, in their new work—at twice, three and four times their former salaries. No Books -- No Lessons I don’t attempt to teach pm by correspon- dence, books, or lessons. I train you on real electrical machinery—not on special training machinery or toy equipment, but on exactly the same kind of machinery you will work on when you graduate from my school— hundreds of thousands of dollars worth of Prepare for Jobs Like These Here are a few of hundreds of positions open to Coyne-trained men. Our free employment bureau gives you lifetime em- ployment service, equipment occupying over 50,000 square feet of our new sanitary fireproof building. You work on real dynamos, engines, power plants, autos, switchboards, transmitting stations— everything from doorbells to power plants— full. sized—in operation every day. Armature Expert up to $100 Wk. Substation Operator up to $65 a Week Auto Electrician $60 a Wk. & up oe are =e sa . Unlimited aintenance Engineer : up to $100 a Week Service Station Owner $60 a Week and up Radio Expert $60a Week andup cessful year. My graduates have made this possible and because of this, I can offer a low price to future stu- dents for a short time. GET THIS Earn While You Learn FREE Book Free Employment Service for Life After You Graduate a cs coe oo om om oe oe te If you are short of money, my Employment Department will help you get i H.C. IE ELECTRICAL a part-time job while you are attending school. Then when you graduate | a ~y men og heey “4 Dept. 99°73 they will help you find the Electrical Job you want. 4 Dear Mr. Lewis :— Without obligation send me your big free catalog { and all details of Railroad Fare to Chicago, Free Employment Service, Radio Aviation and Automotive El Courses you are including and how many “‘earn while learning.’’ H. C. Lewis, Pres.

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134 “The Boss Was Stumped” “He was trying to figure out a way to speed up the machines. I could see he was stumped and I asked him if he would let me try my hand at it. “ ¢Go ahead,’ he said, ‘but I don’t believe you can help much. Looks like an outside job to me.’ “So I started right in and soon I had the whole thing worked out. I could see the boss was surprised. “ “How did you learn all that?’ he asked. And then I told him I’d been studying at home nights through the International Correspondence Schools. “He didn’t say anything more and I thought he had mr all about it until he called me in his office a few weeks later and said he was going to make me foreman and increase my salary $75 a month.” That’s a true story of what spare-time study has done for just one man. There are thousands of others. Why don’t you take up a home-study course with the International Correspondence Schools and prepare yourself to earn more money? INTERNATIONAL CORRESPONDENCE SCHOOLS “The Universal University’ Box 7649-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 position, or in the subject, before which I have marked an X: TECHNICAL AND INDUSTRIAL COURSES Architect () Automobile Work Architectural Draftsman () Aviation Engines Building foreman Plumber and Steam Fitter Concrete Builder Plumbing Inspector Contractor and Builder Foreman Plumber Structural Draftsman Heating and Ventilation Structural Engineer Sheet-Metal Worker Electrical Engineer Steam Engineer Electrical Contractor Marine Engineer Electric Wiring Refrigeration Engineer Electric Lighting R. R. Positions Electric Car Running Highway Engineer Telegraph Engineer Chemistry Telephone Work Pharmacy Mechanical Engineer Coal Mining Engineer ‘cepenion Draftsman Navigation ([) Assayer Machine Shop Practice Iron and Steel Worker Toolmaker Textile Overseer or Supt. Patternmaker Cotton Manufacturing Civil Engineer Woolen Manufacturing Surveying and Mapping LjAgriculture () 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 ffic Management Stenography and Typing Accounting and C. P. A, LJ English Coaching Civil Service Cost Accounting Railway Mail Clerk Bookkeeping Mail Carrier Secretarial Work Grade School Subjects Spanish [ nch High School Subjects Salesmanship Illustrating () Cartooning Advertising, Lumber Dealer Scien banisectdeninsabasniaberieiaansssmesachacstnnaatégianiezessveunionets 60 Street City... titties Minenittitiapsisthinianiectasdescstnehaeancenqseninnreipegnccinenne ° If you reside in Canada, send this coupon to the International Correspondence Schools Canadian, Limited, Montreal, Canada TR) ] 40m ge) START ON A REAL SALARY, WITH EXPENSES PAID Trained men are needed in this important profession. Fasci- nating work; plenty of variety; chances to travel. Advance- ment rapid with experience. Report to high officials. We assist you to a position paying from $120 to $135 a month and expenses upon graduation, or refund your money. Pre- pare in months spare time home instruction. Cost moderate. Send for free booklet “pe Standard Business Training Institute s Div.3 Buffalo, N. Y. POPULAR SCIENCE MONTHLY Rope Handrail for Inclosed Stairs R stairs that are inclosed by two walls, a graceful and serviceable handrail can be made from 114-in. cotton rope, velvet, and a few brass stanchions of the type having a hole all the way through and sold by marine dealers. The stanchions should be brass, pref- erably 31% in. high with a 1%4-in. hole | and a 3-in. base. A handrail lends both beauty and safety to a flight of inclosed stairs. thoroughly, and, when they are dry, apply a coat of clear lacquer. Mount the stanchions except one at top or bottom with 2)4- or 3-in. screws. In determining the length of the rope allow about 18 in. at each end for a knot, which is made in “Turk’s head” or “turban” fashion. Cover the rope with velvet, knot one end only, thread the rope through the stanchions, pull it tight, and mark it just where the knot on the free end should come. Tie the knot after threading the free stanchion on, and put the stanchion in place. Velvet can be sewed over the knots at both ends.—SAMUEL GoRE. Coconut Converted into Novel Table Lamp PICTURESQUE and unusual table lamp can be made as illustrated on the following page from a large, unhusked coconut and some palm stems or shrubbery. The coconut is sawed in two and the meat removed, after which the nut is dried for several days. The stem half is used for the base, the stem being cut off and a hole bored through the shell Polish and wash them | DECEMBER, 1929 New Million Dollar CAN OPENER No More Stabbing and Hacking Just a Twist-of-the-Wrist Opens | Square, Round or Oval Cans, Brings Fortunes to Agents-'6 to 12" Hour Full or Spare Time~ i ey @ little automatic machine that opens any shape can, round, square or oval, in a couple of seo- onds at a mere twist of the wrist! Holds the can for you, and cuts out the entire top, slick, smooth and cl inside the rim—juices can’t spill! No jagged edges to snag your fingers! Ali food pours right out without scraping or spooning! No wonder Speedo representatives often sell to every house in the block and make up to $12 an hour! J. Williamson, Wisc., made 8&5 his first hour. Mrs. Spain, Kans., made 8) her first afternoon. Duncan, Mont., cleaned up 817 his first day. Ornoff, Va., $522 his first month. You, too, can maxe big money with Speedo - Write for Demonstrator Whether you have ever sold any- thing before or not learn the facts FR EE ne nee eee eee. We sh everything including most novel demonstration outfit you ever O ffer saw. No experience needed. Not sold in stores. Three special selling plans for full-time or part-time workers. Act at once and you can test your profits FREE! CENTRAL STATES MANUFACTURING CO. Dept. W-843, 4500 Mary Ave., St. Louis, Mo. | eee ee Oe ! Central States Mfg. Co., Dept. W-843 § 4500 Mary Ave., St. Louis, Mo. Rush me facts and details of your Free Test Offer Z F eB a A definite program for getting ahead financially will be found on page four of this issue. Fall in Love Words have amazing powers. The world offers its treasures of money, power, and position to the skilful users of them. There are words for every occasion—words that thunder commands; words bristling with compelling force; words of zephyr-like deli- cacy; words of inspiration; words of romance; words to bend men’s minds to your will; words to express every shade of meaning. Through a justly famous easy method of spare-time study at home you may make words the playthings of your moods, the tools your necessities. You can learn how to weave them into stories that sell; advertise- ments that convince; letters that win. GET THE FREE BOOKLET “How to Become a Master of English’’ tells you all about the Kleiser Practical English Course which is endorsed by famous writers as Booth Tarkington, Irvin S. Cobb, Mary Roberts Rinehart. Ask for it on a postcard, or write your name in margin return this advertisement, and the booklet will come to you by mail, free of charge. No agents will call. Funk & Wagnalls Co., Dept. 1250, New York, N. Y.

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DEcEMBER, 1929 POPULAR SCIENCE MONTHLY te , Radio Inspectors $2000 to $4500 Radio Operators $90 to $200 a month a Year. (board free). 135 Broadcast Operators $1800 to $4800 Radio Repair Mechanics $1800 to $4000 a Year. a Year. il one of these BIG MONEY RADIO AY “Good Bye” to long hours and low-paid work. Pick yourself a big-money job in Radio! Hundreds of men just like you earn from $2,000 to $25,000 a year in this giant world-wide industry .. . It’s the livest money-making business of today! The Whole World is Calling for Trained Radio Men Broadcasting stations and manufacturers all over the coun- try are eagerly seeking trained men... Thousands of ships require experienced operators ...and now comes nation- wide radio telegraph service, telephony, television, photo- radiograms!... Thousands of opportunities like this are waiting for you. Easy to Learn at Home With This Magnificent Laboratory Outfit There’s no need for you to know a thing about Radio. The Radio Corporation of America sponsors this marvelous, simplified home-training course ... by means of which you, too, can now prepare for success in every phase of Radio... You learn by actual experience with the remark- able outlay of apparatus given with this course... learn how to solve every Radio problem ... such as repairing, installing and servicing fine sets. That’s why you, too, can easily have the confidence and ability to hold a big-money Radio job. Only Course Backed by Radio Corporation of America The progress of Radio is measured by the accomplishments of the great engineers in the huge research laboratories of the Radio Corporation of America. This gigantic organi- zation sets the standards for the entire industry ... and sponsors every lesson in the course. That’s why graduates of this school are always posted in newest up-to-the-minute developments in Radio. That’s why they are always in big demand. RADIO INSTITUTE OF AMERICA JOBS FREE BOOK SHOWS HOW! Money Back if Not Satisfied This marvelous home-laboratory training practically in- sures your success by preparing you thoroughly in every phase of Radio manufacturing, servicing, broadcasting, photoradiograms, television and airplane radio equipment. As a student you will receive an agreement signed by the president of this school assuring you of complete satisfac- tion upon completion of your training—or your money will be instantly refunded. Read This Free Book The young men in Radio today will be the industrial leaders of tomor- row... that’s what happened in the automobile business...in aviation .-eand in every other essential industry...Get in on the ground floor and climb with this tremendous industry! Free... everything you want to know about Radio ... 50 fascinating pages...each one packed with pictures and descriptions about the brilliant opportunities in this fast-growing profes- sion. See for yourself why R.I. A. training has placed thousands of men in well paid positions—usually from 3 to 10 days after graduation. Mail this coupon now and re- ceive your Free Book. RADIO INSTITUTE of AMERICA, Dept. PS-12, 326 Broadway, New York, N. Y. Gentlemen: Please send me your FREE 50-page book which illustrates the brilliant opportunities in Radio and describes your laboratory-method of instruction at home. Name Address. man do itin Y Q months ®

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136 and PRDFEE More and more is electricity lifting the weight of labor from the shoulders of man. If you are not satisfied with your present job, become an ELECTRICAL EXPERT and free yourself forever from the discontent of low wages. You do not need any previous training. Any man who can read and write and use his hands can become an electrical expert. Here is Your Opportunity The NEW YORK ELEC- TRICAL SCHOOL pre- pares you for the BIG PAY profession. First you learn the theories of electricity and then you put them into actual practice. You solve each problem with your own hands. When you have completed your course at the NEW YORK ELEC- TRICAL SCHOOL you can go to any part of the world and be sure of a good living. Write today for the 48-page booklet giving full infor- mation on how to be an electrical expert. NEW YORK ELECTRICAL SCHOOL 40 W. 17th Street, New York powseceesM AIL TODAY ooemny | POPULAR SCIENCE MONTHLY for the electric cord. An ordinary lamp socket is connected to the cord and secured in the shell with plaster of Paris. Three 41% in. long pieces of palm stem or shrubbery (the rougher and more irregular they are, the better the ef- fect will be) are glued in small holes made in the husk to join the two halves together as shown. Threesmall pieces of the same kind of wood are glued to the bot- tom for feet. A small ten-cent lamp shade is fas- tened to the globe by a wire clip, or a shade can be made from a strip of oiled parchment or mica on which any desired design may be stenciled or drawn. Care must be taken to leave an air space both above and below the shade, for ventilation. The lamp is trimmed with pieces of vine and the smallest of pine cones, which are fastened to the outside of the husk with small brads and glue. Flowers may be made by breaking up large cones and using the parts for petals. The exposed fiber where the husk is cut into is filled with putty or clay and the whole varnished.— C. R. McCASHLAND. The finished coconut shell electric lamp. Guide for Drilling Glass HEN the tube method of drilling— or, more properly, grinding—glass is to be used, the most difficult part of the work is starting the drill. An efficient guide can be made from a cut iron washer with a hole slightly larger than the drill tube. A bit of beeswax is melted and poured on the place to be drilled, and the washer is pressed into it. The surplus wax is removed from the hole in the washer and, with a little addi- SMALL DILL PRESS) DRILLING TUBE WELL OF BEESWAX BEESWAX An iron washer and a little beeswax serve as a guide to facilitate drilling holes in glass tubing. tional wax, is formed into a funnel-like well about the drill. The well is filled with turpentine or water, and the drilling proceeds as usual (see “‘ Drilling Holes in Glass,” P. S. M., May ’29, p. 98). This method of making a guide is easily applied to flat sheets or to convex surfaces and gives rigid support at the cut- ting edge of the drill —FRANK E. Gray. DECEMBER, 1929 shows. how you can get into AVIATION * - the book that tells just where your chances are in Aviation today. It gives definite answers to the questions you've been asking yourself—‘‘ What must I do to get into Aviation?”— Walter “What job can I hold?” It ex- Plains how Lieutenant Walter Hi nton Hinton, through a remarkable 1 personalized home-study course, can give you—-RIGHT AT HOME —the groundwork employers de- mand. This intensive home-study course in Aviation is getting cash results for Hinton’s graduates in all parts of the country. He also backs you up with an active employment service when you are ready for a job. If you want to take up flight instruction, he arranges for special reduced rates at an accredited flying school. First to pilot a plane across the Atlantic, first to fly from North to South America, first to use _ the plane in explora- tion, first world- famous fiyer to give home-study students the cream of his hnowledee. Get Walter Hin- ton’s own message to you, his Free Book, “Wings of Opportunity.” Mak Now for Fach 302-B Walter Hinton, President Aviation Institute of U. S. A. 1115 Connecticut Ave., Washington, D. C. Please send me your Free Book showing how I ean train right at home for a place in Aviation. Send for this Free Book. today. The time you now spend thinking abow Aviation could ve spent in training, wD & Ss CREF oc cccccccececesscocseesees DRAW CARTONS Turn Your Talent Into Money Cartoonists earn from $50 to $250.00 r week—some even more. Remark- able new Circle System of Drawing teaches you in half the usual time. Send for booklet and sample lesson late explaining full details of the urse. No salesman will call. THE NATIONAL SCHOOL OF CARTOONING 615 Penton Building Cleveland Government Positions Census Clerks, Clerk Carriers, Rural Carriers, Rail- way Mail Clerks, Postmasters, Department Clerks, and many others. Splendid salaries, easy work, vaca- tion with pay. Only common school education re- quired. Examinations often. Send for our Civil Service Catalog No. 7. COLUMBIAN CORRE- SPONDENCE COLLEGE, WASHINGTON, D. C. “UncleSam’s . Pay Roll a _— 7” FRANKLIN INSTITUTE $158 to $225 7 Dept. C-276, Rochester, N. ¥. MONTH 7 Rush to mo free information can 4 U. 8. Gov’ i Men Boys roi” clerk ‘ris Mal Garet 18 up OF et Oe Sa. Se Mail Coupon ¢ Immediately P | ' 1 s THE NEW YORK ELECTRICAL SCHOOL ' ; 40 N. Y. E. 8. Bupa., 17TH Srreet, New York | 4 Please send me FREE your 48-page booklet. It 4 j is understood that this request puts me under no 3 obligation. ' | a Ee ee a a canes saben esewneuaes 1 H RS, ints cnn dehcus mesdbekbbndedeeensd : ’ J meme

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— l- —— — o> December, 1929 POPULAR SCIENCE MONTHLY 137 R T I QUALIFIES YOU TO MAKE MONEY AND ITS SERVICE KEEPS YOU UP-TO-THE-MINUTE ON R T I. a oe =e THE NEWEST DEVELOPMENTS IN RADIO, TELEVISION, AND TALKING PICTURES e © me WIRY RULUART LL P > 1G = Monev ee ringsBug Jobs Like These! +, ANO_UP > - 10 Engtneer ee atta Ko JOBS Right at You FingerTps oe WHEN YOU ARE RTI. TRAINED IN Ee ery ene dei cena } th it the abov: aE a ea can. RADIO-TELEVISION Talking Pichaes | 5S is kept right up-to-date with last minute information. In a few you can be doing actual Radio work, making enough ExTrRA Money to more than pay for your training. Ina few short months you can all through—ready to step into a good paying job or start a business of your own. A Bic Josp—Bic Mongey—A Bie Future. There is no other business in the world like it. Bic Pay Joss! Spare Time Prorits! A FINE BuSINEsS OF YouR Own! They’re all open to you and other live wire men who answer the call of RapIo. The fastest grow- ing industry in the world needs more trained men. And now come Television and Talking Movies—the magic sisters of Radio. Will you answer this call? Will you get ready for Salary Raised 33 1-3% Since Enrolling a big pay job Now and step into a BIGGER Investigate—Send A may terested that I ONE later on? You can do it EASILY now. ze For R. T. I. Book Now - Radio Service Manarer tor thet. Knight R. T. I. Home Training on’t waste a minute. Find out what ere in the State of Oklahoma, and Texas Puts You In Th: Mone hi Radio Industry, which has die, wi an increase in salary of ebout R di . is Big y Field grown faster than the Automobile _— ge for Sees you 1 pl adi otion Picture business, has to offer i 2 wonderful course, lam, EARL P. o alone, pays over 200 MILLION you. Find out what other men are Gonnon, 6i8 East 6th St., Oklahoma Citys Okla. DOLLARS a year in wages in Broadcasting, earning. SER How Easity You Can Manufacturing, Sales, Service, Commercial GET STARTED. Get the facts about Stations and on board the bigsea goingships, FRED H.SCHNELL = Radio, Television and the Talkin and many more men are needed. Television Chief of R. T.1.Staff Pictures, first hand, in the big R. T. y . . Twenty years of Radio FREE Book. Learn what this R. T. I. and Talking Movies open up othervastfields Experience. Firsttoestab- “Three in One” Home Training can of money-making opportunities for ambi- an ae noe go’ Seryeu. Malt the Coupon for tious men. Get into this great business thatis Former Traffic Ma ne Radio & Television Institut live, new and up-to-date, where thousands League Lieut. Commander Dept. of trained men easily earn $60 to $100 a Ry cetierens > 4806 St. Anthony Court, Chicago week—where $10,000 a year — are plenti- Consultant Radiokngineer. ful for men with training plus experience. Roy chare of BT Easy ToLearnAtHome—InSpareTime Wor of helsing you resins Learning Radio the R. T. I. way with F. H. your ambition. Schnell, the “‘Ace of Radio” behind you is Easy, INTERESTING, really Fun. Only a few spare hours are needed and lack of education or experience won’t bother you a bit. We furnish all necessary testing and working apparatus and start you off on practical work you’ll enjoy—you learn to do the jobs that pay real money and which are going begging now for want of competent men to fill them. Amazingly Quick Results You want to earn BIG Money, and you want some of it QUICK. R. T. I. “Three in One” Home Training—Radio-Television-Talk- ing Movies—will give it to you, because it’s easy, practical, and Haven’t you. How could {when high as $25.00 day and have made \ fe high an $B from Radio work. That’s not sce when I’m only 19 and in aemall town. I inst over the catal you sent me before ¢ tPA tra and you did t all_ you said you w it ich .—FLoYn KNISELY, v a8 Ue EE. D. 2, Box 91, St. Joe, Ind. J RADIO & TELEVISION INSTITUTE =" Dept. 39, 4806 St. Anthony Court, Chicago 1 Send me Free and prepaid your BIG BOOK | “Tune In On Big Pay”’ and full details of your three-in-one Home Training (without.obligating | me in any way). | 4 | Name R TT r TRAINS YOU AT HOME FOR A GOOD JOB OR A PROFITABLE e eo me PART TIME OR FULL TIME BUSINESS OF YOUR OWN > ria .

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POPULAR SCIENCE MONTHLY Get the Facts? Where the New Motor Cars Excel (Continued from page 76) drive would be through all four of the wheels. Kellogg silently thumbed through the cata- logues for a while and then he popped another question. “What is a down-draft carburetor, Gus?” he asked. “That’s the latest,” Gus replied. “The air flows down through the carburetor into the cylinders, instead of uphill. The air doesn’t have to lift the gas particles uphill and the air velocity can be a lot lower. That allows a larger opening through the carburetor, which means more power at high speed, and still the mixture is right when the throttle is nearly shut. If they put the same big air passage in the ordinary carburetor to get the same top speed, the air would go through so slow when the engine was throttled that it wouldn’t carry up enough gas. It’s a swell idea. I wonder why somebody didn’t think of it before.” “Humph!” grunted Kellogg. “Maybe the new cars have more power, but what have they done to make ’em last longer? I'll bet a new car wouldn’t give me the service I’ve gotten out of this boat.” ” ELL, let’s see,” Gus ruminated. off, they’re doing a better job of making cylinder castings now than they used to. The new nickel-iron alloys wear better than the old gray iron castings. Also, they know more about how to design a cylinder block so the cylinder walls won’t warp out of round as bad | as they sometimes did in the old days. Then there’s the crank shafts—they’re grinding ’em more accurately and balancing ’em a lot better. Pistons are lighter; so are connecting rods. All that means less vibration, and less vibration means less wear. * All the good cars now have thermostats to control the water temperature. The motor heats up quicker and even a careless driver can’t run ’em much too cold in winter. There’s less crank case dilution to spoil the oil’s lu- bricating qualities and the oil filters they’re fitting keep the oil clean. Air cleaners keep dust out of the cylinders, and that cuts down the carbon quite a bit. Higher compression means better economy. “As for looks, the modern lacquer finishes | stand up three times as long as the old paint finish, and the chromium plating on the bright | ” parts stays bright without polishing. “Gosh!” Kellogg exclaimed. “I thought all that stuff was just talking points. But even if it is true, how about the bodies they’re putting on the cars these days? They look pretty light and tinny to me. The body. on my car is better right now than most of the bodies on the new cars.” “That isn’t a fair comparison,” Gus ob- jected. are remarkable considering the price. You can’t expect a fine hand-built coach job for a hundred dollars or so. It costs that much for “First “T think the bodies they’re fitting now | DECEMBER, 1929 Only 4 Motions used in instrument. Our native teach you to master them quickly. Pictures show how. Everything explained clearly. Playin Half Hour Easy Lessons After you get the Even if you don’t four easy motions know one note from you play harmonious another, the 52 chotds with very printed lessons and little practice. No clear pictures make previous musical it easy to learnquick- nowledge needed, ly, laying this meee awaiian Instructors Pay as you play. GIVEN when you enroll —a sweet toned HAWAIIAN GUITAR WRITE AT ONCE for attrac- tive offer and easy terms. A postcard will do. ACT! OTHER } Tenor Banjo, Violin. Tiple, T G courses] Banjo Ukulele. "Under «Tenet Guitar, Usulle FIRST HAWAIIAN CONSERVATORY of MUSIC, Inc. 9th Floor, Woolworth Bidg., Dept 246 New York, N. 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DECEMBER, 1929 POPULAR SCIENCE MONTHLY Fossil Monsters I Have Hunted (Continued from page 57) of the duck-billed dinosaur, Trachodon. I flopped carelessly on a ledge of sandstone to rest for a moment, only to leap up quickly with a long tear in my trousers and a cut in my leg. The very end bone of the fossilized tail of some prehistoric monster had pierced me. Following it back, I found the finest specimen of a Trachodon yet unearthed. Four of us worked ceaselessly for two and a half months ex- cavating this monster, the skull of which, alone, was more than four feet long. The entire specimen weighed approximately five tons. It was shipped to the Senckenberg Museum, Frankfort-on-the-Main, Germany, where it now is. [Hts great lizard, weighing probably ten tons when alive, apparently had been trapped in quicksand and had sunk to its death, for the front limbs were lifted up along the sides of the body, and reversed, revealing the perfectly preserved webs which had cov- ered the feet. The head and neck were stretched to their full length, as if the Tra- chodon had been struggling to escape the grasping sands, while the hind feet were pointed downward, showing an effort to swim out. Most remarkable of all, the entire body was covered with skin, not clinging to the bones, but well filled out, as if by the rounded muscles of life. The sand had taken the place occupied by the flesh in life, and thus, for the first and only time, we had an opportunity to see and study the exact form of a dinosaur, not the imagined form of a restoration. We had not the proper lifting equipment— tripods, blocks, lines, and hooks—with which to handle the great weights of the three sec- tions, some 3,000 pounds each, into which we cut the stone block containing the skeleton. But with simple machinery made from two stout cottonwood poles and two blocks of the same wood, we could raise a section a few inches off the ground and hold it there while others of the party shoveled sand beneath and tamped it hard. Thus, in a week, we raised one section some four feet into the air so that a wagon could be backed under it. Then, by placing cottonwood rollers in the bed of the wagon, we shoved the block of stone aboard and hauled it to the railroad station, many miles away. Accompanying the blocks of stone to the museum is a detailed map of the location of the find. This map is made by the fossil hunter on the spot. Photographs are also sent to com- plete the information that guides the prepar- ator in assembling the skeleton. When the blocks of stone have been unpacked, a color- less, thin, but very penetrative cement is poured into the exposed ends of the bones, from which the organic material, of course, has long ago disappeared. This is allowed to “set” until every small particle of fossil bone is bound firmly together. Then, with power drills and chisels, the sandstone is cut away, the plaster of Paris packing having been removed by the simple process of unwinding the burlap strips. S THE stone is removed to the areas pene- trated by the cement, more cement is applied until eventually the brown bones, each solidified by the cement, stand clear of as much of the stone as the preparator desires to re- move. Some skeletons, particularly those found in perfect conditions, are mounted “flat,” in the slabs of stone in which they were discovered. Others, which may have been distorted by the pressure of the sand in process of petrification, have to be removed, placed in their proper positions, and set up on steel tubular frames. This is particularly true of the larger dinosaurs, mammoths, prehistoric rhi- noceroses, and the vari- . (Continued on page 140) 139 BE AN ARTISTY and be your own boss F you like to draw, why drudge when success and a good income may be yours through art training? Publishers pay millions of dollars yearly for illustrations. Many successful Federal Students are earning from $2500 to $6000 a year — some even more. If you hold yourself down to a routine job you may always do uncongenial work. But if you like to draw and are willing to train your talent, your art ability may help you to success in life. Through the Federal Course in [Illustrating more than fifty famous artists give you the benefit of their methods of Illus- trating, Cartooning, Lettering, Poster Designing, Window Card Illustrating, etc. You may learn through the experience of these successful artists how to bring your own drawings to a profes- sional standard. They understand the methods that make art pay well. You can keep your present position while gaining your art training. 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POPULAR SCIENCE MONTHLY DECEMBER, 1929 *# =“ Monsters I Have Hunted (Continued from page 139) ous forms of the early horse. The “ser- pents” and other swimming lizards, the fishes, and some of the smaller dinosaurs, are mounted in the “flat.” Frequently, in large specimens, bones will be broken and entire bones will have disap- peared. It then becomes the duty of the preparator to rebuild the missing bones out of a specially-prepared composition, or to obtain the missing bones from other incomplete Since this latter is seldom possible, the preparator must | become an anatomist and a sculptor, if the fossil skeleton is to be complete. He first ob- tains from some other specimen a bone as nearly like the missing one as possible. Then he models a copy of this, and places it in its proper position in the skeleton he is mounting. F HE is unable to obtain such a bone, he must model one by reversing, in his mind, its mate on the opposite side of the skeleton. Two months of steady work sometimes is required to model and replace a single bone in a large skeleton, or to rebuild a shattered bone. Reconstructions of the skeletons and bodies of prehistoric animals and reptiles have been made from a single bone or a solitary tooth, but at best this is uncertain. Some years ago, seven different and distinct prehistoric sharks had been identified and classified on a basis of one known tooth of each. In the ancient sea beds of Kansas, I found one fossil shark which contained all these seven kinds of teeth | in its own jaw, proving that at least six of these | restorations had been wrong. It was along the petrified rim of this pre- historic sea in Kansas that one of the strangest of my accidental discoveries took place. I stooped to study more closely a group of fossil gastropods, laying aside my hand pick to do so. When I lifted the implement, the point had caught in the mouth of a long-buried skull just below the ground. Carefully working back toward the body, I uncovered the ancestor of all the sea-serpents, a Tylosaur about thirty feet long. This was a sea-living reptile, at- taining a length of fifty feet or more, carniv- orous, and probably the “tiger of the seas” five million years ago. Tas interesting fossil lay with snout, all four flippers, and tail extended, just as it | had been overwhelmed by an avalanche of sand while swimming unsuspectingly near the shore. The position of the skeleton told us the complete story of the character and habits of this father of all sea-serpent stori¢és. There was no distortion, and the skeleton was lifted out in three slabs of sandstone, which were put together again, and the TJ ylosaur displayed like a picture in a frame. We shall never know whence came the sand which overwhelmed and preserved this Ty- losaur, but from the work of the sand we do know very closely the appearance of this strange swimming lizard in life. My studies of all the known forms of dinosaurs leads me to believe that some day we will find specimens which will change our conception of these animals. The dinosaur was a huge lizard, some varieties living on land, some in the water, and Diamonds—Skyscrapers Built of Atoms (Continued from page 50) of common salt. Like the crystals of granulated sugar, those of ordinary table salt are made purposely of a small and uniform size to fa- cilitate solution and to make the salt flow easily. This is controlled by making the salt crystal- lize at a definite speed when it is being refined. For scientific purposes much larger crystals of clean, pure salt are grown artificially. From ee some impartially on both. Now, all known lizards, from the great saurians 'to the tiny chameleons, walk with their feet outside the | line of the body and with the belly dragging on the ground. Some of them can, and do on oc- casion, stand erect on their hind feet, but this is not a habitual pose with any of them. In the restorations of the dinosaurs in virtually all museums, the dinosaur is repre- sented as standing on all fours, like a mammal, with the feet inside the line of the body, again like a mammal, or standing and running on the hind feet. In either instance, the belly—which was entirely unprotected and open to attack from the carnivorous dinosaurs—is lifted well up from the ground. Without studying the fossil skeletons in their positions in the rocks, the logical paleontologist would believe that these lizards should be pictured with their hind limbs curved out, like those of an alligator; the feet outside of, and at right angles to, the line of the body, and the belly close to the ground—exactly the posture of the lizards of today. My observations of the skeletons of a hundred or so dinosaurs, which I have discovered and excavated, confirms this belief, we I consider my most important dis- covery in six decades as a fossil hunter is the finding of complete skin-impressions of a crested duck-billed dinosaur. Prior to this finding, there had been much discussion as to | the character of the skin which covered the giant frames of these great lizards. In a rock- walled gorge, a mile wide and five hundred feet deep, in Alberta, Canada, I discovered the virtually complete skeleton of this duck- bill, Stephanosaurus marginat is. The small scales of the skin, often mere tubercles, polygonal in shape, were arranged like mosaic in a pave- | ment in parallel rows, along the abdominal walls. Later, I found other impressions of the skins of other dinosaurs, and some fragments which are believed to be the actual skin itself, so thoroughly fossilized as to be almost in- distinguishable from the impressions or “molds” in the stone. This discovery enables us at last to picture with fair accuracy the external appearance of the dinosaurs of these varieties, and, as we know from the skeletal remains their interior arrangements, we now can present the com- plete duck-billed dinosaur of the crested or crowned species just as it appeared when it strode along the shores of the Cretaceous Sea, or swam in its waters. ‘THE weapons of the fossil hunter are pick, crowbar, chisel, soft brushes, cement, bur- lap, and plaster of Paris. Sometimes, when he finds a skeleton projecting from the face of a cliff, he turns carpenter and builds a lofty platform on which to work as he removes it. Again, he calls in dynamite, and blasts his treasure unbroken from its natural sarcophagus of stone. There are not more than half a dozen of us, but I doubt if any hunter, facing a charging elephant or an angered rhino, ever felt any greater thrill than we do when we stumble upon a new variety of monster, pos- sibly the remote ancestor of these big-game animals of today. these are cut the prisms and lenses, for example, — in studying the invisible rays of infra-red ight. The distances of the atoms from each other in the unit cube of the salt-crystal have been measured with exceptional precision. These distances are almost unbelievably tiny. Imagine a crystallograph- (Continued on page r4r)

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DEcEMBER, 1929 Diamonds—Skyscrapers Built of Atoms (Continued from page 140) er possessed of a magic drug to enlarge things or to make them smaller. Suppose him to pour a dose of it over a small cube of pure salt a half-inch square, about the size of average dice. Let the drug enlarge this salt cube until one from New York to San Francisco. In this gigantic enlargement the atoms will still be less than five inches apart in a continual, regu- lar pattern across the United States and an equal distance up into the air. HIS half-inch cube of crystallized salt, about as much as the average person eats in a plate of soup, contains more than eleven thousand billion billions of the unit cubes of the atomic pattern. Most promising practically of all scientific researches on crystals is that concerned with metals. The strength and the weakness of metals are due, it has been discovered, to their internal crystals. On one hand is duralumin, the new, very strong alloy of aluminum, copper, and other elements which makes possible modern airships like the Los Angeles and the Graf Zeppelin. The strength of this alloy is due to myriads of tiny metal crystals scattered be- tween its larger crystals of aluminum. These tiny grains keep the larger ones from sliding past each other and allowing the metal to pull apart. The same strengthening process occurs in some alloys of copper and other metals. pPusroseri. control of crystal forma- tions is the chief object of modern metal- lurgy. Much has been learned by melting and cooling different metal compositions and ex- amining under the microscope the kinds of tiny skyscraper structures that form. Much more will be learned if the laws which control the arrangement of atoms in the unit pat- terns can be learned and their applications worked out. Other properties of crystals have begun to be important, too, in other sciences. In radio, plates cut from natural crystals of quartz, or “rock crystal,” vibrate mechanically when sub- jected to the back and forth electric swings of a radio circuit. These crystal plates are now used almost universally to keep radio stations precisely on their assigned wave lengths. In optical instruments, quartz crystals are used, for example, to measure and analyze the rays of ultra-violet light now known to be beneficial to health, while crystals of Iceland spar and other minerals are used to study polarized light and to make the instruments for quick analysis of the amount of sugar in things like sugar cane. Examination of snow crystals promises to tell weather experts much about conditions in the upper air, far above levels which can be reached by balloons or air- lanes. Artificial ice crystals made in the aboratory have disclosed facts previously un- known about the nature of so familiar a sub- stance as water. mye Examination of crystals under special mi- croscopes has told experts in microchemistry the kind of drug contained in an empty medi- cine wrapper picked up by the police at the site of a suicide and murder. Similar observa- tions regularly disclose to geologists conditions which must have existed when rocks were formed, like a specimen poured out thousands of years ago on the sea bottom of the Atlantic Ocean and dredged up by a recent scientific expedition. To make diamonds larger than ostrich eggs has no great appeal to scientists. | But thou- sands of scientific men willingly would give years of their lives to discover just why it is that the South African carbon atoms consented ages ago to crystallize in the atomic pattern of diamonds but are so reluctant to do the same thing nowadays in scientific laboratories. edge of it stretches across the United States ° POPULAR SCIENCE MONTHLY J. E. Smith, Pres., National Radio Institute, Washington, D. C. 141 Making men successful in Radio 1s my business For fifteen years I’ve given.all my time to training men and young men for good jobs in the Radio Industry. Today Radio needs more trained men Read these letters about increased pay than ever before. I am getting calls for my graduates regularly from broadcasting stations, Radio fac- tories, dealers, jobbers, shipping companies and many other branches. My 64-page book, “Rich Rewards in Radio”, points out where the good Radio jobs € are, what they pay and how to get one. I am Doubling and Tripling the Salaries of many in one to two years $400 a Month “Twas making good money but could see the opportunities in Radio. Believe me, I am not sorry I took your course, for I have made more than ever before. I have made more than $400 each month. I can’t say too much for your school.” J. G. DAHLSTEAD, 1484 S. 15th St., E., Salt Lake City, Utah Seldom Under $100 a Week “My earnings in Radio are many times greater than I ever expected they would be when I enrolled for your course. They seldom fall under $100 a week. For November they hit close to $600, for December $535. Can you blame me for singing praise for the N. R. 1?” E. E. WINBORNE, 1414 W. 48th St., Norfolk, Va. I gwe you parts for a home experimental laboratory With them you can build over 100 circuits including the. latest using screen-grid tubes, push-pull ampli- fication and other modern set features. Eight big outfits without extra cost. This method gives you practical ex- perience while learning equal to two to four years in the field. You grad- uate trained and experienced. The photograph below is one of the many circuits you build. J. A. Vaughn, 3715 S. Kingshighway, St. Louis, Mo., jumped from $35 to $100 a week after com- pleting my course. E. E. Winborne, 1414 W. 48th St., Norfolk, Va., seldom makes under $100 a week. Many of my men make $10 to $25 a week on the side while learning. My practical method of home training makes learning easy, fascinating. Your Money back if not Satisfied I make this agreement with you. If you are not en- tirely satisfied with my lessons and Instruction Service upon completing your course, I will refund every cent you have paid me. judge. Television, Talking Movies, Radio’s use in Aviation and all the latest developments in and uses for Radio are covered by my course. You are the only Everyone Interested in Making More Money should read my book I have written a 64-page book which outlines the opportunities in Radio, my methods of training, the unlimited Employment Service given graduates and many other features that have made my course famous. I will gladly send you a copy free of cost and without obligation to you. Simply clip and mail the coupon below. Do it now. J. E. Smith, President, NATIONAL RADIO INSTITUTE, Dept. 9ZQ, Washington, D.C. This coupon will bring you free information about my course ekoowoes A eed tee J. E. Smiru, Pres. Bi National Radio Institute, Dept. 9ZQ La Washington, D.C. Dear Mr. Smith: Without obligating me, send your book, “Rich Rewards in Radio”. be a ae

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H * = PO MBROED oo ccc ccccccccccccccccccccccccccscce = STTTeTiITLieeLLLLLLLL | POPULAR SCIENCE MONTHLY A New World Run by Dynamo (Continued from page 21) proved machinery for generating and trans- mitting electric current, it suggested a novel source of factory power to forward-looking engineers. When the steam engine was invented there was just one way to carry its power to a dis- tant place. That was with a belt or a shaft. An old-fashioned shop was a forest of pulleys. There was nothing like “central station” power. Imagine what a small town, even, would look like if power were transmitted from a central plant to factories by ropes and belts. But here was electric energy. It could be shot over small wires that could be bent around obstacles. There was little loss of power in transmitting it. Where it was used it could be transformed into other forms of energy than | mechanical power—light, heat, and chemical energy used, for example, in electroplating. It was an ideal form of power. S° THOUGHTFUL engineers, little by little, began to substitute it for steam and other forms of power in factories. They did it so quietly that the average person scarcely real- | ized what was being accomplished. But today the world-wide revolution nears completion. English factories today are forty-eight percent electrified. German factories lead them with sixty-six percent electrification. But the United States tops the list with seventy-eight percent of its industry run by electricity. Better ways of transmitting electric power over great distances, and huge power stations to generate it, have made the revolution pos- sible. Not long ago the engineers of a 220,000- volt transmission line between Vaca and Pit River, Calif., wanted to find out what would happen in case the wires fell. They deliberately connected one of them to the ground and turned on the power. There was a crash and a burst of flame twenty-five feet high. Then the automatic safety devices operated and shut off the current before damage had been done. Great electric companies have spent thou- sands of dollars photographing the effect of lightning strokes on transmission lines (see page 33). The result has been lightning-proof power lines hundreds of miles long to convey power safely to distant industries. Today 23,674 miles of transmission lines operate at voltages of 66,000 volts or more to deliver rivers of electric power across country. LONG with the electrical revolution came super-power. As early as 1910 a mid- western utility company made a daring experi- ment. Twenty-two small towns, .with popu- lations of from 300 up, were chosen as the group on which to try it. Ten of them had electric companies of doubtful financial stand- ing, the other twelve none at all. The utility company first bought the existing power sta- tions and closed them. Then it built trans- mission lines to all the towns and to 125 farms and hooked them to a few central stations. It was the cheapest electricity the section had ever known. Twenty-three thousand small-town dwellers and farmers were suddenly treated to twentieth-centyry electrical service, and the section prospered with industry as never before. That successful experiment ap- plied today on a much greater scale in many parts of the country is “the beginning of the national super-power that engineers dream of —the vast reservoir of energy that can be tapped by a factory or a home anywhere. Soon a single operator may sit at a switch- board and throw the switches that distribute electric power to every city in the United States. Electricity may be cheaper and more abundant than anyone has ever dared hope. In the near future the electric revolution may give mankind untold leisure and new conven- iences for enjoying it. 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2 DecEMBER, 1929 [The Moon Is Made of Cinders (Continued from page 45) high. Other ring mountains are almost as large and some are higher. No volcano on earth has ever constructed so gigantic a crater as this one. The difficulty lessens, however, when one remembers the much smaller gravity of the moon, as compared with that of the earth. A firecracker on the moon would blow up a house, for all material things weigh much less there than on earth, as one result of the moon’s smaller size and mass. Accordingly a given amount of volcanic explosion on the moon would throw far more material into the crater’s ramparts and would shoot out this material to far greater distances than would be the case on the earth. The darker, flat looking areas on the moon, which early astronomers named “seas” or “Jakes” and which mostly form the Man in the Moon’s picture, are probably places where a general blanket of volcanic dust and broken pumice settled more or less evenly as near- -by eruptions ceased. Every feature of the moon’s surface may be explained as the result of vol- canic activity combined with weak gravity. Probably the volcanoes were of the type repre- sented on earth by those of Hawaii, where a large, round crater is built up and its flanks sprinkled occasionally with pumice and vol- canic dust, without eruptions of the enormous- ly explosive type like that which destroyed, over forty years ago, the East Indian island of Krakatoa. (THERE is one part of the moon, it must not be forgotten, which no terrestrial astrono- mer has ever seen nor ever will see, until the projected moon rocket or some similar vehicle is a reality. This is the back of the moon, for the moon turns the same face continually toward the earth. There is no reason to believe, however, that the hidden side is notably differ- ent from the visible side. From time to time in its motions the moon tips slightly one way or the other and exposes glimpses around its edges. What they show is the same as the moon’s front. If the explanation of the moon’s appearance is exclusively a volcanic one, the question arises whether all this enormous eruptive energy has altogether ceased. A renewed volcanic out- break on the moon creating, for example, a new crater as gigantic as Copernicus or the other giant named Tycho, would form a remarkable spectacle for the earth. That is scarcely prob- able, but there are minor evidences of waning moon fires. The apparently flat floor of the lunar crater named Plato shows changes of color from time to time, perhaps due to shadows, but ascribed with greater plausibility to vapors escaping from the mountain walls or from fissures in the floor. Professor W. H. Pickering, formerly of Harvard but who now has a private observa- tory in Jamaica, recently called attention to the fact that the lunar crater named Stevinus sometimes appears as though its floor were luminous and of a brown tint. ERHAPS the best observation of apparent changes on the moon has been made by a French amateur astronomer, M. G. Bidault de l’Isle, of La Guette. Between August, 1927, and September, 1928, this patient observer watched on every clear night a small, volcano- like peak which projects above the smooth floor of the larger crater named Posidon, lo- cated between the two dark lunar areas called, poetically, the Sea of Serenity and the Lake of Dreams. At times, M. de I’Isle reports, this tiny cra- terlet, less than a terrestrial mile in diameter, seemed as clear and sharp in outline as any other feature of the moon. At intervals, how- ever, it was in- (Continued on page 144) POPULAR SCIENCE MONTHLY 143 The Byrd Expedition chooses these books P. F. Collier & Son Company New York. Gentlemen: In fitting out the Byrd Antarctic Expedi- tion for a two-year scientific research of the Antarctic, members of the expedition have suggested that we include in our library Dr. Eliot’s Five-Foot Shelf of Books. Books will play an important part in the contentment of the personnel, particularly when the expedition winters on the ice bar- rier through the six months of total darkness during the Antarctic Night. We should like to carry into the Ant- arctic along with your good wishes for the success of the expedition, a set of the Harv- ard Classics. You can appreciate too, aside from the indorsement value of our including the Harvard Classics in a library necessarily restricted in size, that the sixty men who will accompany Commander Byrd on this expedition will while away many hours of enjoyment and profit immensely by the fund of information contained in your volumes. Trusting that we may have your co- operation, Yours very truly, BYRD ANTARCTIC EXPEDITION Ricuarp G. Bropxy, Business Manager. 4 + a La This letter was written to P. F. Col- lier and Son Company by the Manager of the Byrd Expedition, asking that the Harvard Classics be added to their very limited library. The Publishers were pleased to serve Commander Byrd and his men. The selection of Dr. Eliot’s Five-Foot Shelf of Books is typical of the vision with which the whole voyage has been planned. Men of the highest type need the best possible reading recreation, and the Harvard Classics have brought in- spiration and pleasure to hundreds of thousands, DR. ELIOT’S FIVE-FOOT SHELF OF BOOKS The Harvard Classics Men in the ice floes of the Antarctic need be no more remote than the people in our civilized urban world, so far as their reading is concerned. Although the explorer is limited to the few books he can take with him, we of the busy world may be so hopelessly lost in the millions of books around us that we miss the truly great ones. The explorer must choose. And the Byrd Expedition has chosen the Harvard Classics. Because Dr. Eliot, forty years Presi- dent of Harvard University, recognized the need for easy access to the best books, he assembled in one convenient set the works which have everlasting value, the books that stimulate, inspire, and advise. In these volumes are in- cluded the writings of 302 immortal authors. Through Dr. Eliot’s Five-Foot Shelf people have found that the classics are not dull, but intensely stirring; not beauti- ful antiques, but lively, stimulating, modern thought with vital application to everyday life. P. F. Collier and Son Company has published good books since 1875. By the famous Collier plan, you can pay for — books while you read and enjoy them. THIS FREE BOOKLET Before you spend another penny for books, get a copy of “Fifteen Minutes a Day’’---the booklet that tells how to turn precious spare time into profitable entertainment, growth, and in- creased power. It’s ready and waiting for you. 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The Moon Is Made of Cinders (Continued from page 143) visible, apparently obscured by some kind of | cloud or mist. On a few occasions, when the sun’s rays fell just at the right angle on this apparent cloudlet, it seemed to be shining by reflection, as a cloud of steam coming out of one of the Yellowstone Park geysers might look to an aviator many miles above the earth. Such observations suggest that there are still active on the moon a few small volcanic vents, like hot springs or geysers on earth. Doubtless | the new giant telescope which is projected for erection in California and which will bring the moon’s surface to within an apparent distance of about twenty miles from the earth, will dis- close further details. Meanwhile, it is reason- able to imagine that the moon, although dying, is not quite dead. 4 ethaps it still has impor- tant secrets to tell. It is not even certain that the moon utterly lacks life in the sense of living creatures. Sev- eral years ago Professor Pickering, the same who referred recently to the apparent changes in the craters, reported what seemed to him to be moving shadows on the moon’s surface. He suggested the possibility of herds of migrating animals, perhaps like the migratory grasshop- pers of earth. There is little evidence for this, yet to deny the possibility of moon life is even more foolishly dogmatic than to assert its existence. on the moon, unless the vapors which M. de V'Isle believes that he has seen contain some | water. But there are creatures even on earth which can live with an incredibly small supply of water or air. There is no doubt that airless life forms would have developed on the moon had life started there from a germ as on earth | and continued its evolution to suit lunar con- | ditions instead of terrestrial one:. SSUMING this living moon germ of the same kind as the earth germ, perhaps even derived from the earth when the substance of | the moon was torn away, it is possible to imagine what any present moon creatures would be like. have, like terrestrial crabs and insects, to pre- vent loss of bodily fluids into airless space. Energy they would obtain, it is probable, by absorbing sunlight, perhaps through contriv- ances like eyes which could turn sunlight into food, somewhat as plants do on earth. For the substance of their bodies, the moon creatures might depend on mineral elements like silicon and iron in the pumice of the moon’s surface, decomposing this powder, perhaps, by acid gases excreted from their bodies underneath tentlike appendages closed down on the soil to protect the ensuing chemical operation from the vacuum of space. HE bodies of the moon creatures would te slim, jointed, and very light, to suit both the | soft surface of the moon and the lesser gravity. There might be pads, like snowshoes, on the creatures’ feet, to walk on the loose dust. Water must be one of their necessities, at least in minute amounts, for the life-germ of earth has never developed without enough water to keep its living protoplasm partly liquid. Buta little water probably i is still available on the moon in the gases from the dying volcanic vents. One might imagine the strange moon creatures col- lecting around these openings at the proper moment to catch the precious vapor by con- trivances like the gills of a fish. From these | volcanic gases they might obtain, too, the acids necessary to decompose pumice of the | soil for food. Fantastic as such a picture of moon creatures may seem, baseless as it is in anything except speculation from the known facts of life’s his- tory on earth, it is not impossible. Perhaps, some day soon, larger telescopes will disclose whether any of ‘it is true. Air and water, it is true, are lacking | A hard outer shell they must |

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7 DeEcEMBER, 1929 i ‘““How I Fly My Plane’”’ (Continued from page 48)

except special flights. A magnetic compass is easily compensated, or set at true north, by means of screws which shift the magnets farther from or nearer to the needle. If a pilot follows a highway for any distance, he can see plenty of accidents. Every once in a while, two of the little black flies, crawling along the chalk line, can be seen bumping into each other. Sometimes, when the ceiling has been low, I have sailed along over farmhouses so close I could distinguish the color of flowers in little pots sitting on the back porches. After I go over a route several times, I be- gin to recognize people out in the back yards. I remember one time I was flying low over the mountains of the South. A little clearing appeared below. Paths spread out from it in all directions. I circled around to see what was going on. The result was a couple of bullet holes in my wing. Those moonshiners were taking no chances! But being shot at from the ground is play compared to dodging lightning in the sky. I have been up in electrical storms so severe that everything got as black as midnight and little blue sparks played all over the bracing wires of the Waco biplane I was flying. Once a thunderbolt hissed so close it seemed to miss the wings by inches. In the air you don’t hear thunder, you just see the flash. ‘THE ground below, on a cross-country flight, spreads out like a patchwork quilt. Each patch is a field. If the motor calls it a day and quits suddenly, the ques- tion always is, which patch to land on. Ina forced landing, the best rule is: ‘‘ Pick your field as soon as possible—and don’t change your mind.” There are certain things to help in the picking. For instance, fields with cattle grazing in them are likely to be good land- ing spots. By studying the colors of different crops from the air, a pilot can learn to spot fields with growing crops too tall for safely setting down a ship. High grain and grass can be recognized by the ripples a breeze makes sweeping across it. Approaching a field, it is often possible to see spots greener than the rest. They are depressions or damp places, to be avoided. In winter, except when fields are covered by snow, there is a better chance to see what the ground is like than in summer. In set- ting a ship down in a field that requires an uphill landing, the plane is flattened out almost into a stalling position, with the tail well down, just before touching. I al- ways avoid downhill landings whenever possible. They too often mean nosing over in a somersault. THE hardest part about landing is judg- ing distance. I’ve found a pilot is likely to overestimate distance in landing in bad light or when the field and background are of the same dull color. He is likely to under- estimate it when the light is good or when he is coming down with the sun at his back. In poor light, he overshoots the field, or ‘reaches it before he has lost speed and allti- tude. In good light he frequently under- shoots it. When he sees his glide is carrying him too far, he can sideslip off some of his speed and altitude. But if he undershoots, the only thing he can do is to slap on the throttle and climb for another try. For this reason, it is well to come down with the motor idling, or to “blimp” it on and off at four or five second intervals. if a pilot comes down with the switch cut and under- shoots, the motor may not start when he needs it—and needs it bad. As I come in, when the ship nears the ground, I usually keep (Continued on page 146)

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Fraternities. Sta- tion WISN is operated from this school. CLIP THE COUPON! State What Course Interests You Classes are now organizing. Don’t delay. Get into your chosen branch of electricity. Insure your fu- ture in the great field of unlimited earnings and capectnanin. the coupon now! Founded 1993 Dept. PSM-1225, Milwaukee, Wis. Without shligsting me in any wag. pisase mail free 4 ted book illustra Rise to Success ough Elecciic- ity,”” and partic: wats fegarding ... course I have marked with an X RESIDENT COURSES lectrical . Degree (3 Years). > Sommercial Electrical Engineering. (H. 8. Grad- “aan? a 1 yours others 1/2 years). Winding. Light Motor Wiring and ‘Vustis. .--, Electrical Refrigeration. ee Electrician. come Reardon (Home Study Course.) 1 am Interested in your “earn While You Learn” plan. _ ....Day ....Evening Classes. Name....... ..-Age I es Siti sii cnagcenbmedonttoceoneed aE re | POPULAR SCIENCE MONTHLY **How I Fly My Plane” (Continued from page 145) of the plane. The moment the wheels touch is the critical one. Twenty feet up, a ship may have one wing low or be sideslipping all over the place. That is forgiven if she straightens out before the wheels touch. Out in Missouri, I once had to bring down a ship in the dark ‘with half the landing gear gone. I was flying home at dusk when the motor quit over an orphan asylum. I sat down in the front yard and got the engine going. When I took off, a snag of a dead pine that stuck up ten or ‘twelve feet caught _ my eyes on the field about thirty yards ahead | the axle and ripped loose one wheel. I circled | around a while wondering what to do. Then | | I headed for a cornfield where I knew the | ground was soft, sideslipped the plane down, | and landed on the one good wheel. The whole gear crumpled under the weight, but otherwise the ship wasn’t even scratched. I HAVE often thought of what I would do if I ever should find myself in the air with both landing wheels gone. To save the ship, I think the first bet would be to set her down in water. Next best would be to make a sharp dip, striking a hard-packed field with the landing gear struts, wiping them off, and then come down, scooting the machine over the ground like a sled on _ the bottom of its fuselage. But I don’t care to carry out that experiment if I can help it! Put end to end, my hours in the air would make practically half a year of continuous flying, night and day. Yet, I learn some- thing new on every cross-country tri increasing piloting skill, the sky’s the limit. NEXT MONTH: “How I Got Into the Air” The first of a series of in- structive articleson aviation By ASSEN JORDANOFF This veteran pilot of sixteen years’ experience made his first flight as a boy by jumping off a shed on a barn door. Since then he has flown nearly 4,000 hours. Readers of this magazine remember him as one of the instructors who taught Larry Brent how to fly. 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oe . ~ DecEMBER, 1929 Back of the Month’s News (Continued from page 55) Probably not more than a score of persons in the world ever saw a sample of pure man- ganese, but everybody sees and depends upon an article for which manganese is essential. This is modern steel. One of the first great uses of steel containing manganese was to make “tin hats” in the war, but nowadays most of the steel used in industry contains a little of this element. Toughness of the metal is increased by manganese; brittleness is pre- vented; strength, working ability, and other properties are improved. Manganese is ‘medicine for steel,” said C. P. McCormack, metallurgist, at a recent meeting of the American Institute of Mining and Metallurgical Engi- neers. A compound of manganese is used, too, is where manganese is needed most. Deposits of manganese ore exist in Washing- ton, New Mexico, Minnesota, Montana, Vir- ginia, and Georgia, but American mines have never been able to supply the entire quantity needed for American steel. That is why imports of manganese from Brazil are heavy. It is also why American interests have recently con- tracted for supplies of manganese ore from Soviet Russia. In the iron ore regions of the Great Lakes much manganese occurs but, by a natural mis- fortune, the manganese minerals are so widely scattered through the ore that the recovery of manganese in useful form is very difficult. Re- cent experiments, however, have been promis- ing; some by the United States Bureau of Mines, others by commercial interests. Some day soon, it is probable, American mineral deposits will supply the country’s manganese demand—a most desirable outcome, since military officers estimate that lack of man- ganese would be one of the country’s most serious handicaps in case of sudden war. Water Fleas and Heredity ICTURES of water fleas are being hung up nowadays in most of the world’s laboratories of biology. For these tiny creatures are likely to prove among the most interesting, scien- tifically, in the world. Thanks to researches by Dr. Arthur M. Banta, of the Carnegie Institu- tion, water fleas already have supplied one of the best examples of the operation of heredity, and almost the only example known to science of the artificial control of sex. The water flea is not really a flea. It isa microscopic crustacean, belonging to the same great group of animals which includes lobsters, shrimps, and crabs. Water fleas live usually in fresh-water ponds which fill up in the spring and fade away to dryness in the autumn or early winter. To survive the winter thé tiny crea- tures construct a special kind of egg, which sur- vives dryness and cold, and hatches promptly in the spring. The hatched creature is a female. Under normal conditions, Dr. Banta finds, every one of this spring crop of the creatures is pre- cisely like its mother. Heredity is perfect. Sometimes, however, there occurs what animal breeders call a “sport.” Dr. Banta found one water flea which was able to live in water about ten degrees hotter than that which would kill its brothers and sisters. This variant creature bred true, its offspring having the same heat-resisting quality. Thus evolu- tion may have proceeded to produce races of creatures able to live under new conditions. In the society of the water fleas males play a small role, but they exist, especially in the fall, to fertilize the eggs. What causes males to be produced, Dr. Banta finds, is the crowding of the population of females as the pond begins to shrink. By the artificial overcrowding of mother water fleas, or by denying them enough food, they may be made to produce more males and fewer females; an important step, perhaps, toward better understanding of the phenomena of sex in other creatures also. in making dry batteries, but the steel business | POPULAR SCIENCE MONTHLY 147 ENTS) INVENTORS! ~~ “Wyite for these FREE BOOKS) At the left Is a view o my drafting and speci- fication offices where a large staff of experienced experts is in my constant employ. All drawings and specifications are pre- pared under my personal supervision. LAW OFFICES OPPOSITE U-S- PATENT Protect Your Ideas Take the First Step Today If you have a useful, practical, novel idea for any new article or for an improvement on an old one, you should communicate with a competent Registered Patent Attorney AT ONCE. Every year thousands of applications for patents are filed in the U. 5. Patent Office. Frequently two or more applications are made for the same or sub- stantially the same idea (even though the inventors may live in different sections of the country and be entirely unknown to one another). In such a case, the burden of proof rests upon the last application filed. Delays of even a few days in filing the application sometimes mean the loss of a patent. So lose no time. Get in touch with me at once by mailing the coupon below. Prompt, Careful, Efficient Service This large, experienced organization devotes its entire time and attention to patent and trademark cases. Our offices are directly across the street from the U. S. Patent Office. We understand the technicalities of patent law. We know the rules and requirements of the Patent Office. We can proceed in the quickest, safest and best ways in preparing an application for a patent covering your idea. Our success has been built on the strength of careful, efficient, satis- factory service to inventors and trademark owners located in every state in the Union. Strict Secrecy Preserved— Write Me in Confidence All communications, sketches, drawings, etc., are held in strictest confidence in strong, steel, fireproof files, which are accessible only to authorized members of my staff. Feel free to write me fully and frankly. It is probable that I can help you. Highest references. But FIRST — clip the coupon and get my free book. Do THAT right now. No Charge for Information on How to Proceed The booklet shown here contains valuable information relating to patent procedure that every inventor should have. And with it I will also send you my “Record of Invention” form, on which you can sketch your idea and establish its date before a witness. Such evi- dence may later prove valuable to you. 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148 ig Schoolat Ho a a tf) 4 rene S HIGH SCHOO COURSE IN TWC YEARS ao aw re ee You cannot attain business or social prominence. You are barred from a successful 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 itions 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 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 édie 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 Dest. H-948 Drexel Ave. and $8th $?., Chicago American School Dept. H-948 Drexel Ave. & 58th St., Chicago Send me full information on the subject checked and how you will help me win success, anv Architect «-+ee Business - ‘Build ng Cc ae ew .....&atomebile Repairman ~.. a, inal Civil engineer «see SHOp Superintendent oisetd Structural Engineer «ose employment Manager egal Manager ooee SCORN ageacer ose CFt. Public «-.-Foremanship ——e and Aaditor ......Sanitary Paasineer om ooeeee SUPVEYOr ping) and —— amd ——geeunens Engineer & Power =--High a iy 1 REE 8 POPULAR SCIENCE MONTHLY Why Minds Behave As They Do (Continued from page 29) white robes of surgeons and nurses at emer- gency dressing stations, he said, adding that hysteria during the mental strain of terrific fighting made conditions ripe for “startling psychic manifestations.” A ten-year-old boy who mysteriously felt impelled to chew the lapels and sleeves of his coat, and a young girl of good family who for lapses of days or a week took on a different per- sonality and associated with undesirable strangers, were examples of strange mental cases helped by psychoanalysis which Dr. A. A. Brill, of New York City, described. These troubles, he asserted, were eventually cured when their causes were discovered by Freudian methods. The boy, for instance, was found suffering from excessive ‘‘mothering’’ following his father’s death, which produced a peculiar reversion to thumb-sucking and other tenden- cies of childhood. In the young girl’s case, her father’s “rigid fanaticism”’ had given her a narrow morality so repressive that it produced a dual personality. Her “other self,”’ during the lapses, loosed all the pent-up force of her repressed desires, in actions of which she would later have no con- scious memory. Psychoanalysis seems the only effective ap- proach to the cure of such patients, Dr. Brill said, and its skillful application requires a com- plete knowledge of the patient’s constitutional make-up and reactions. Psychological interneships in general hos- pitals were urged by Dr. Mabel Ensworth Goudge, of Chapel Hill, N. C. Often the psychoanalyst and the physician must coéper- ate in treating a case of nervous disease or other disorder, she said, and in some cases a psychological cure is aided by the physician’s drugs and physiotherapy. Tests of Intelligence “TNTELLIGENCE tests,” which began as measurements of ordinary brain-power, _ now determine an individual’s “emotionality,” | photographs of six “sense of humor,” “personality,” and even admissibility to a school of music, experts told the Congress. The discomfort of a needle pressed into the palm of the hand, a peg pressed into the wrist, and an electric current flowing through the hand, formed part of a unique “torture test”’ given to a hundred students, and described by Prof. Thomas B. Howells, of the University of Colorado. It was designed to measure the students’ persistence or “stick-to-it-iveness.” The high scorers, who voluntarily endured the most discomfort, proved to be leaders in other intelligence tests, Professor Howells said. Most persons assume they know the differ- ence between “right” and “‘ wrong”’ acts, said Prof. Vernon Jones, of Clark University. But when he asked 168 school-teachers to mark “right,” “wrong,” or “excusable” sixty-eight childhood actions suggested in a novel ques- tionnaire, he found wide disagreement, he re- rted. One question was whether a child should shield friends he had seen meddling with a railroad switch, wrecking a train. On only twelve out of the sixty-eight questions did even ninety percent of the teachers agree. Bible students, contrary to belief, are as likely to lie and cheat as anyone, Prof. P. R. Hightower, of Butler University, concluded after a test he gave 3,316 school children. The test offered eight chances to cheat, two to lie, two to show loyalty, and two for altruism and service. Other tests measured Bible knowledge for comparison. The idea that intelligence always shows in a man’s face is a popular myth, asserted Prof. Richard S. Uhrbrock, of Cornell University. He asked six hundred men and women to judge (Continued on page 149) DECEMBER, 1929 PATENTS TRADE-MARKS SERVICE Without charge or obligation, we will inform you on any questions you may put to us touching on patent, trade-mark and copyright law. You may ask: “Should I protect myself by patent, or register under the trade-mark or copyright laws? What kind of a patent should I obtain?’’ and many other questions that may occur to you. These are vital points to consider and questions will be cheerfully answered. Don’t Lose Your Rights To Patent Protection Before disclosing your invention to any- one send for blank form “EVIDENCE OF CONCEPTION” to be signed and wit- nessed. As registered patent attorneys we represent hundreds of inventors all } over the United States and Canada in the jit advancement of inventions. The form if “Evidence of Conception,"’ sample, instruc- |} tions relating to obtaining of patents and ii schedule of fees sent upon request. LANCASTER & ALLWINE 274 Ouray Building Washington, D. C. Originators of forms, ‘‘ Evidence of Conception.’’ TO THE MAN WITH AN IDEA PATENTS Procured. Trade-Marks Registered. —A comprehensive, experienced, prompt service for the protection and development of your ideas. Preliminary advice gladly furnish without charge. Booklet of information and form for disclosing idea free on request. IRVING L. McCATHRAN PATENT LAWYER Formerly with and successor to ichard B. 705 International Bidg., Washington, D.C. 41-D, Park Row New York City TRADE - MARKS REGISTERED ‘INVENTORS Mey coun PATENTS and pay for them on the basis of Deferred Payments Inventors Service Bureau Dept. A, Union Trust Bldg., Washington, D. C. PAT E N T INVENTIONS Edward Gottlieb * ATTORNEY IN PATENT CAUSES 5 Beekman Street, New York Inventions Developed—Representative for Blair Tool and Machine Corp. PATENTS Trade-marks, Copyrights, Patent Litigation, Handbook with illustrations, 100 mechanical movements. Sent free on request. ALBERT E. DIETERICH Formerly member Examining Corp. U. 8. Patent Office Registered Patent Lawyer and Solicitor 30 years’ experience 681-A Ouray Bidg. Washington, D. C. Seach w tts,

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DecEMBER, 1929 POPULAR SCIENCE MONTHLY . 149 Why Minds Behave As They Do (Continued from page 148) of the highest and six of the lowest scorers in a Cc @) PY R | G ry T S recent intelligence test. Four of the twelve OUR OFFE ~ FOR THE PROTECTION OF YOUR INVENTION were wrongly called intelligent or nonintelli- 4 gent. The photograph of a high scorer mis- judged as “nonintelligent,” particularly by women, showed a drooping may snarl, and averted eyes. But more women than men cor- wid P rectly classified as “intelligent” a pleasant- YOUR FIRST STEP The inventor faced man smiling agreeably and looking should write for our blank form straight at the camera. “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 Why People ‘‘Get Mad’’ our fireproof secret files. We will also ye makes people angry was the subject give our opinion as to whether the of a novel study reported by Prof. Hulsey Cason, of the University of Rochester. He invention comes within the Patent Office definition of a patentable in- compiled a list of more than 2,600 different vention. This “Record of Invention” annoyances submitted to him by students, along with estimates of their relative disagree- will serve as “proof of conception” until the case can be filed in the TRADE-MARKS ableness. Among them were “‘someone reading my newspaper over my shoulder,” “‘a person pushing in ahead of me in a waiting line,” “audible conversation next to me at the movies ora music recital,” and “‘being told to do some- thing when I am about to do it.” ‘é ioe 8 ” iv VICTOR BUILDING ° ~ oe eee in my face Rar on Our New Building Nearly Opposite U.s. | Patent Office. There is no charge one of the highest scores as a source of extreme Patent Omies ocala Erected by bli ° f, hi ° annoyance, as did the sight of a young person Us for Our Own Use oro igation or this service. treating elders with disrespect or an adult abusing a child. Jazz music, Professor Cason found, exasper- = { ates older persons more than younger ones. 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 Countries, 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 CONFIDEN- TIAL. INTERFERENCE AND INFRINGEMENT SUITS PROS- ECUTED. Our Large, Comprehensive Organization has been established for 30 years and offers Prompt, Efficient and Personal Service by experienced Patent Lawyers and Draftsmen. We shall be glad to have you consult us or to Mind- Measuring Machines A NEW vacuum tube machine, described by Dr. S. R. Hathaway, of Ohio University, ! gives criminal suspects a psychological third- degree. Tried out on 100 college women during an epidemic of stealing in a women’s dormitory, it showed their reactions during conversation to words connected with theft. Other devices that test breathing or blood pressure also give a criminal away or trap him in a lie, but they should be used only by experts, Dr. Harold E. Burtt, of Ohio State University, stated. Persistence of vision, the secret of motion pictures which lies in the eyes’ ability to pre- serve the image of an object for a moment after it disappears, is strikingly demonstrated in a train of luminous flashes by a special type of neon lamp described by Dr. Walter R. Miles, of Stanford University. Motions of the hand in performing complicated movements are now being studied, said Dr. J. van der Velt, of the University of Rome, by attaching a tiny flick- ering lamp to the subject’s finger. A dotted- line record is caught on a photographic plate. One of the first machines ever devised to test a man’s ability to judge relative speed helps select bus drivers in Barcelona and Paris, re- ported Dr. Emilio Mira, of Barcelona, Spain. Rods worked by electricity are started toward each other on a fifteen-foot table at different speeds. Subjects are asked to guess quickly at what point they will meet. Excellence in this type of judgment may save an auto driver from a collision. Learning from Animals answer any questions in regard to Patents, Trademarks or Copyrights without charge. N “APE farm” is to be established in Highest References—Prompt Service—Reasonable Terms Florida by Yale University, its president, Dr. James R. Angell, revealed to the psycholo- SaaS Tana : ; gists. At this farm the animals will be bred and FREE VICTOR J e EVANS bh Co. ! raised in order to study the psychological and COUPON Registered Patent Attorneys: Established 1898 ; — problems of animals and human censeunssecesesd MAIN OFFICES: 690 Ninth St., Washington, D.C. mgs. , BRANCH OFFICES: 1007 Woolworth Bldg., New York City; 1649-42 Conway Bldg., Chicago, ; Even goldfish have helped psychologists, Ill.; 514 Empire Bldg., Pittsburgh, Pa.; 828 Fidelity Phila. Trust Bldg., Philadelphia, Pa.; ’ said Prof. Raymond B. Wheeler, of the Uni- 1010 Hobart Bldg., San Francisco, Calif. versity of Kansas. Forty of them, in tests, Gentlemen: Please send me FREE OF CHARGE your books as described above. ; demonstrated their reaction to strong and : weak light and showed smartness in choosing ae PPP Rewer re ae PP mre Ry ee | | preference to either— (Continued on page 160) II o-oo 0::0:0 0:0:0:n ch sce a tw cnn psaihiiien acme cg eens cee ew) |S MAGTEB.... 2.22. oe cesseceserercrscscescectdoccscsccrsccssssedeessnns esp eese emus

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150 “Ought to put over Money- making Idea, o know YOURSELF. His mind nibbles at EVERYTHING and masters NOTHING. He always takes up the a thing first, puts it down when ts HARD, and starts something else. i MPS 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? 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 BR ‘AIN-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 negative 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, Vix know this man as well as you — Don’t wait. Mail the coupon THE PELMAN INSTITUTE OF AMERICA Suite 8712, 71 West 45th Street, New York City The Peiman Institute of America Suite 8712, a West 45th Street ity New York C Please send me without ob! aeien your free ‘Scientific Mind Training.” is does not : ae me under any obligation and no salesman is to Just: POPULAR SCIENCE MONTHLY Why Minds Behave As They Do (Continued from page 149) despite the fact that lights were constantly shifted about to deceive them. A principle demonstrated in this test was also verified in another upon rats by Dr. J. A. Gengerelli, of Yale University—the “‘Law of Least Effort.” He showed that rats crossing a box to reach food will soon discover and thenceforth fol- low the shortest route from corner to corner —a diagonal straight line. Psychology Put to Work REVISED jury system, a better way of putting advertisements in magazines, and A advice to actors playing emotional scenes are | latest suggestions for the practical application of psychology. Advertisements need not be mixed with magazine stories, declared Dr. Harold Burtt, of Ohio State University. He prepared two “dummy” magazines. Each contained twenty pages of advertising and twenty-five of reading matter. In one the advertising and reading pages alternated. In the other they were in separate sections. Subjects remembered the “ads” equally well after looking through each for ten minutes. Present-day juries should be abolished, de- clared Prof. Harry Elmer Barnes, of Smith College. A board of examiners, most of them psychologists, should try criminals. Mental disorders predispose many to crime, said Dr. F. A. Moss, of George Washington University. A criminal record may be an “acci- dental expression’’ of a person’s mental condi- tion, agreed Prof. Joseph Jastrow, of New York. A stage actor portrays emotion best when he keeps just aloof from it, said Prof. John T. Metcalf, of the University of Vermont. A vivid mind-picture of anger or love serves the | actor better than the sensation itself. Drugs and Moonlight QTRAN GE effects of the Oriental drug hash- ish, made from the flowers and leaves of Indian hemp, were described by Dr. Erich Lindemann, of the University of Iowa. Ob- servers who volunteered for tests of hashish | intoxication found that their sense of touch, in | particular, was strangely altered. object repeatedly handled seemed to swell to huge size. Another common form of illusion was distorted judgment of elapsed time. Dr. David I. Macht, of New York City, reported that exposure to polarized light caused death to drugged rats, while other drugged rats exposed to ordinary light recovered. He treated rats with camphor or cocaine—two drugs pro- ducing convulsions of the brain. The polarized light, which differs from ordinary illumination in that its light waves vibrate in a single plane instead of helter-skelter, made the convulsions fatal. The results were particularly interesting because natural moonlight, once popularly be- lieved to ‘‘make people crazy,” is known to be largely polarized. Man and Woman ARRIAGE makes a man’s mind more feminine, Prof. L. M. Terman, of Stan- ford University, declared in a paper he sub- mitted to the Congress. A small | Having analyzed | masculine and feminine traits in the minds of large groups of men and women, he reported that environment often plays an overwhelming part in shaping them. A “he-man” in appearance may be more feminine in thought than the average woman, he said, since physical appearance has nothing to do with the mind in either sex. After a few years of marriage husbands, he found, are likely to take on a more feminine outlook in interests, preferences, and emotional reactions. DECEMBER, 1929 $165,000 'REWARD for an IDEA That sum was paid to the inventor of “Kiddie Kars.” Here is a remarkable book which tells you what inventions are NEEDED in every field. Don’t waste your ideas. Send today for 1000 NEEDED INVENTIONS Prepared by Raymond F. Yates, famous inventor, former managing editor.of Popular Science Monthly, who knows what manufacturers want. New, re- vised 1929 edition. This book may start you toward a fortune. Send no money. Just write a postcard. Pay mail man only $1.50 plus postage when book arrives. Money back after ten days if desired. Limited offer. Write now. Get started in right direction. (Outside U. § $1.70 cash with order.) 7 Bureau of Inventive Science 212 Wisner Blidg., Rochester, N. Y, —~ one ot fee yo pat- pd inventors at Rap service noted for results, evidenced by many well leume Patents of extraordinary value. Book, Patent-Sense, Lacey&Lacey 648 FSt., Wash., | D.C, Estab. 1: 2. UNPATENTED IDEAS CAN BE SOLD I tell you how and help you make the sale. Free particulars. (Copyrighted) Write W. T. Greene, 921 Barrister Bldg., Washington, D.C. INVENTORS We have been in business 30 years. 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Le ined DECEMBER, 1929 | Welding—the Silent Builder | (Continued from page 31) special screens are used to eliminate ordinary light, and with it the obscuring haze. Only penetrating invisible rays of infra-red light are | used to take the picture. In this way successful motion pictures were made of the operation of welding. They showed exactly how a drop of metal interrupts an electric arc when it touches the weld, and how it spreads out to fuse with the metal. From such photographs, three of which are reproduced on these pages, improved welding methods are foreseen. In the early 1900’s a welder announced: “We do the impossible. We weld cast iron.” Steel was then the only metal ordinarily welded. Today any known metal in commercial use can be welded, as evidenced by copper tanks, bronze statues, and aluminum coffee pots. Nearly all welding today is done by one of four methods—two electrical, one by gas, and one by chemicals. Age welding, an electric process, uses the heat of an electric arc to produce a flow of vapor forming the arc reaches the temperature of six or seven thousand degrees Fahrenheit. The light from the arc is blinding. An arc welder wears a hood that calls to mind the armor of medieval knights. Its window is a special screen of glass so dark that nothing may be seen through it except while the electric arc ison. A spray of molten metal sparks flies from work being welded with the aid of the arc, which is really a flame of hot gases. One terminal of the electric circuit is the welding rod itself; the other is the work to be welded. To start the work, an arc-welder, holding in his shielded hand a rod electrically wired, lightly touches it to the joint to be welded. This closes the electric circuit, and the welder creates the arc by moving the rod a fraction of an inch away from the piece to be welded. The heat of the arc keeps the rod melting. The welder slowly draws the arc along the joint, which becomes filled with metal from the melting rod. The work-piece itself is also partly melted by the heat, making a perfect fusion with the rod’s metal. This method of welding, which can also be performed by a welding machine, is especially adapted to mass production of metal articles, as well as to | structural work. Not everyone knows that arc- | welding is the oldest form of all. It was first | tried in France, in 1881, for joining parts of storage battery plates. XY-ACETYLENE, or gas-torch welding, uses the 5400-degree flame of acetylene gas and oxygen burning fiercely at a blowpipe’s tip to fuse and weld metal. A rod of suitable material held in the flame supplies the extra metal needed for the joint. Although not as intense as the electric arc, the light of this flame would blind an operator in time if he did not wear protecting dark goggles. Some idea of the violence with which the oxygen supports com- bustion of the gas is given by odd experiences of veteran welders. Cases are on record where the valve of a tank of compressed oxygen, used on welding, has leaked, oil present somewhere has caught fire by spontaneous combustion, and soon the brass valve has itself caught fire and showers sparks: under the tremendous oxidizing power of the oxygen stream. Gas-torch welding is a widely used hand method, especially for repair work. It is adapted to welding small metal pieces. The first workable oxy-acetylene torch was de- veloped by two Frenchmen, Fouche and Picard, in 1900-1901. “Thermit welding” and “spot welding” are the two other principal methods, each with a rather restricted but important application. More like a Fourth of July celebration than an industrial operation seems a thermit welding job, to a layman’s eye. (Continued on page 152) liquid metal to form the weld. The heat of the. | culations, Code, Electric Railways, Elevators, POPULAR SCIENCE MONTHLY 151 Every What Wants to KVOW/ | SUST OUT! Latest Exact Information From A to Z! | - Announcing: ‘‘Audels New Electric Library.” New and More uses for Electricity offer great opportunities to men who can handle this power correctly and accurately. “‘Audels New Electrical Library” is a NEW practical and theoretical course for home study and ready reference. Here are the answers to your questions, giving you the real dope that every electrician must know. 7 Books Now on Sale—65 in Preparation—The first 7 books (now ready) contain over 3600 pages with thousands of diagrams and illustrations; the remaining 5 books are in preparation. NEW! Beautiful, timely books for service—-pocket-size, flexible; e completely illustrated; simplified, easy to read and under- stand. No electrical man can afford to pass up this opportu- nity. 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Alternating Current, Power Factor, Trans- formers, A-C Motors, Windings, Converters, Switches and Fuses, Relays, Condensers, Rec- tifiers, Meters, Power Station Practice, House Light and Power Wiring, High Tension, Cal- THEO. AUDEL & CO., 65 West 23rd St., New York Please ship me the NEW “‘Audels Electric Library’ on the plan marked (X). Gas Engines, Auto and Aero Ignition, Radio, Telephone, Telegraph, Motion Pictures, Talkies, Lighting, Electric Refrigeration, X-Ray, Welding, Pumps, Compressors, Ap- genes, An Electric Calculator, Practical athematics, A New Electric Dictionary and Encyclopedia of Words. EMPLOYMENT FOR 500 AGENTS AT ONCE Mitchell, So. Dak.—Walter M. Willy, of this city, is in need of 500 men to help market his new and amazing invention which makes glare from passing automo- biles impossible. This device fits and matches all cars. It can be installed in a ELECTRIC REFRIGERATION minute. It is inexpensive. 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See tor yourselt and address it to W. M. Willy, W-331| is tobecome a highly paid refrigeration expert. Ueilities . an Logan Bldg., Mitchell, S. Dak. Lean herid: ET ES TTS SK SS. a LS ae cae a rR TEENIE Ss ee MRR VO Fa NVENTORS your ive YOUR IDEAS Write for our Guide Book, ‘“‘HOW TO GET YOUR PATENT,” and Evidence of Invention Blank, sent Free. Tells our terms, methods, etc. Send model or sketch and description of your invention for INSPECTION and INSTRUCTIONS FREE. Terms Reasonable. Best References. A a a oe ot a oo =e =—V RITE TODAY—----——— --- QOCUPATION oo. cccccccccccccccsccesiedsocecsccsssbessorssescd ° EMPLOYED BY. ......0.ccccccccccccsicccsccccsccccooccess 12T34 VALUABLE BOOK ON | RANDOLPH & COMPANY, Patent Attorneys . Dept. 130 Washington, D. C. 7 hele en ee

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DeceMBeEr, 1929

Welding—the Silent Builder (Continued from page 161) This chemical welding process consists of placing a crucible filled with “thermit,” a mixture of iron oxide and metallic aluminum, above a mold containing the pieces to be welded. A piece of red-hot iron or a match is used to ignite an inflammable powder which, in turn, ignites the mixture in the crucible. A fierce reaction follows. Showers of sparks, re- sembling the “flower pots” used in fireworks celebrations, are tossed off from the seething crucible. Molten iron pours from the bottom of the pot into the mold, where it fuses with the metal to be welded. This method is particularly applied to bulky welding opera- tions. It has been used successfully to weld breaks in large shafts, castings, and the stern- posts of vessels. GFoT welding, used for ‘“‘tacking”’ together large sheets of metal at spots along their edges, is an electric method that differs It applies heat from the inside of the work instead of from the outside. Metal sheets are clamped in a press which shoots an electric current of low voltage but tremendous amperage through them. The metal’s own resistance to the current instantly fuses it at the points of contact. Machines have been developed that do spot welding at high speed. Not long ago the General Electric Company, after researches conducted by Dr. Irving Langmuir, noted physicist, announced a novel method of welding—‘‘atomic hydrogen weld- ing”—to be added to the standard processes. By its means, hitherto unweldable metals can be melted and fused without the slightest trace of oxidation, and welding can be per- formed in some cases on metal as thin as a sheet of paper. Briefly, this method utilizes the passage of a stream of hydrogen through the arc between two electrodes. The heat of the arc breaks up the hydrogen molecules into atoms. These atoms recombine a short distance beyond the arc into molecules of the gas, and this process liberates an enormous amount of heat, so that more effective welding temperatures can be obtained than with the ordinary welding methods. The apparatus for this process was de- veloped for commercial use in 1927. Its principal feature is the torch with which the actual welding is done. This consists of a holder supporting two tungsten wire elec- trodes, electric conductors connecting the electrodes to a reactor, and tubing for the hydrogen gas. Each electrode is supported on a nozzle through which the hydrogen gas is forced out around it. ‘Lhe electrodes are set at an angle, and the distance between the elec- trodes is adjustable, as is the flow of gas. TOMIC hydrogen welding differs from other methods in that there is no flow of current from the electrodes to the work to be welded. The electric conductors to and through the torch are heavily insulated, and, when welding ceases, the welding current is automatically interrupted until the operator is ready to weld again, when the circuit is automatically restored. The most important feature of the hydrogen process is the absence of oxidation from the welded metals. Since atomic hydrogen is a powerful reducing agent, it reduces any oxides that might otherwise form on the sur- face of the metal. Because of this absence of oxides and nitrides from the weld made by it, this process is particularly adaptable to the welding of special alloys—such as those of chromium, nickel, copper, aluminum, and sil- ver—and will also make a strong, smooth, and ductile weld on ordinary iron or steel work. Startling as are some of the present uses of welding, researches such as these may disclose

still other useful applications. aa

i eee

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DeceMBeER, 1929 POPULAR SCIENCE MONTHLY 153 Tihs OFFER $ Here Are Correct Answers to Questions on Page 55 1. The human eye is practically a miniature camera which has a lens, an iris, and a retina, the sensitive nerve surface that registers the light impression. If, through some structural or muscular error, the lens does not focus the image on the retina, vision will not be clear and glasses will be needed to correct the | condition. 2. Astigmatism is an optical distortion caused by an improperly formed cornea. The cornea is the spherically shaped glasslike surface at the front of the eye. If this surface is not a | section of a true sphere but is curved more in | one direction than in another, the image formed on the retina will be sharp only in the lines of the image running in one direction. If such an eye observes a chart consisting of lines radi- ating from a central point, only one set of lines at one particular angle will appear sharp. The TRAINED MAKING *60 to5100 A WEEK angle, of course, will depend on the direction of the irregularity in the cornea. The glasses used to correct this condition are ground plain on one side and curved like the section of a cylinder on the other to neutralize the dis- tortion produced by the irregularity in the eye structure itself. 3. The human eye lens, like a camera lens, can focus objects sharply at only one distance from the eye at a given instant. When the eye is directed toward other objects farther from or nearer to the eye, the focus of the lens must be changed. This changing of focus is called accommodation, and is accomplished by mus- cular action in the eye. As people grow older the accommodation becomes poorer owing to deficient muscular action. It frequently hap- pens, therefore, that an older person cannot focus sharply objects either far away or close at hand. Two pairs of glasses are needed, or a single pair of the so-called bifocal type, in which the lower section corrects for reading and the remainder of the lens for distance. Why don’t you get into Electricity, too? It’s today’s great Opportunity for you and every other man who is sick and tir of struggling along on small pay. Hundreds of “Cooke Trained Men” who were no smarter than you when they started now make $3,000 to $5,000 a year— and some make even more. LEARN AT HOME IN SPARE TIME Learn with the famous L. L. COOKE “Work Sheet and Job Ticket’”’ Method. It’s simple, it’s thorough, it’s practical. It’s just like actual shop experience, yet it’s all done right in your own home with the Big Complete Outfit of Tools and Ap- paratus given to you without extra cost. And it’s done in your our time, without quitting your present job or losing a single 10ur’s pay. PREVIOUS EXPERIENCE NOT NEEDED You don’t need previous experience—you don’t need higher education to learn Electricity the L. L. COOKE Way. If you can read and write, that’s enough. This great Training is aw clear and simple. There’s nothing like it anywhere. It’s the Training with hundreds of successful graduates; it’s the Training that has put many men on Easy Street; it’s the Training for you. GET STARTED -- MAIL COUPON ‘‘Cooke Trained Men” are the “Big Pay Men” everywhere. $60 to $100 a week is what many of them are making. That’s the kind of a job for you. Get started under the famous L. L. KE Money Back Agreement. Act today to increase your pay. Send coupon for Big FREE Book, ‘‘Secrets of Success in Electricity.” Mail coupon now. L. L. COOKE SCHOOL OF ELECTRICITY Dept. 39, 2150 Lawrence Ave., Chicago, Ii. FREE BOOK COUPON, L. L. Cooke School of Electricity Dept. 39, 2150 Lawrence Ave., Chicago, tl. Send me entirely free and fully prepaid, your book “Secret, of Success in Electricity.” with particulars about your Hom, Study Course in Electricity. 4. An eye that is nearsighted is unable to focus objects at some distance from it. Tech- nically, this trouble is known as myopia. It can be corrected by a lens ground flat on one side and curved inward on the other, so that light rays from distant objects are dispersed through the lens of the eye as though they came from nearer objects. DORs o's Shad oo) 2 5s is weed 6 cease shove debe tereeaaeeee 5. A flat-shaped lens gives the proper correc- ag aaa tion only for objects directly in front of the Residents of Canada may send coupon to R. A. Farrow, Special eye. As the eye is turned in its socket the stg ns mammrieersdcmor sc wr light rays are sent through in a diagonal man- | tt By ; ie “72 : ' ner away from the center, and distortion re- | / The Cooke Trained Man ZS the BIg Pay Man \ sults. Toric lenses are ground in curves. One re side usually is a section of a perfect sphere gym _Manulacturing and the other side is a section of a sphere to . SPECIALTY which the correction for the eye trouble has _ added or subtracted. The toric lens is | } - 7:99 0) 8) ANGE INVENTION! esirable because it gives a wider angle of our Original *ikew Bystees Gonctaltn Canae hint . ~\, Boer a you’*30,A y for immediate production. QUICK RET we Son eANeaT BUSINESS of YOUR OWN, Mg distortionless vision. 6. The human eye is designed to be in con- ee ee stant operation at all times during waking Drawer on” MMLVER RAGEOST Grange, N. J, hours. In fact, the eye is always in use so long as the eyelid is open. Of course, the read- AVIATION ing of very fine type, especially in poor light, Information F R E E and certain types of work requiring extreme visual concentration, such as drafting, fine sew- -— LT 4 Bo monde fo way ow hen ype yn ‘usanl tole ane Re me ing, and so on, put a continual strain on the the many great opportunities now open and how we prepare NEW KIND OF CORD SET FREE eye. There is, however, no definite limit to | you at howe, during spare time, to qualify. Our new book REE the somes the use of the eyes, as it varies with different | Opportunities in the Airplane Industry also sent pe | = wae Ay: free if er at once. ou individuals. YAMERICAN SCHOOL OF AVIATION ST eclach sles, Sees mage Dept. 1369 3601 Michigan Ave. CHICAGO and saves clenerie » bile, - & Assuming that the eye trouble is purely A A a ayo ee P in optical = is fully corrected by the lenses of A definite program Don't dalay! ‘Send now for ree the eyeglasses, there is no difference in light NEVE trie requirements for a person with glasses and one he Gees cnet Dept. 12-¥ res = with eyes not requiring glasses. In any case, financially will be the light should come over the shoulder and found on page four in ample volume for (Continued on page 154) of this issue

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154 7; Wouldn’t You A fade Jobs With ™* A transport pilot flying tri-motor planes — working six pleasant hours a day — earning from $8,000 to $10,000 a year. Wouldn’t you trade your job for his? You can if you only try. With proper training and experience you, too, can become a high salaried transport pilot. wot Skea eae - * _ Learn Aviation by Flying. Whether you intend to become a line pilot or plan to enter any of the dozens of other branches of avia- tion, you should know how to fly. Men who are doing big things in aviation today are flyers. So it will be in the future. Take a course in a Universal school — a school operated by the largest operating system in the world — and get the kind of training and experience that really counts. Other Courses in Aviation Offered In addition to flying courses Universal Avi- ation Schools offer courses in Aviation Mechanics, Aviation Business, and for those who plan to enter aviation later, a corre- spondence course in aviation groundwork. Send for outline of training. Take This Step Now! Get into aviation while the field is still open. The time to start is NOW. Investigate what Universal Aviation Schools offer you. Check the coupon below, fill it in and mail. Universal Aviation Schools A Diwision of The Aviation Corporation .__, §t. Louis, Mo. ee Minn. rae re arion, Ill. . Oklahoma City, Okla. s '« ester, Minn. UNIVERSAL AVIATION SCHOOLS Suite 1046-55 Boatmen’s Bank Bldg. St. Louis, Mo. Please send me at once your free book, “Aviation — What lt Means To You.” I am interested in: CLIP COUPON nn | Sa O Flying Course 0 Aviation Mechanic’s Course O) Business Course (Correspondence Course POPULAR SCIENCE MONTHLY Here Are Correct Answers to Questions on Page 55 (Continued from page 153) distinct vision, but not in such great quantity as to cause glare. 8. Farsighted eyes are so constructed, or the muscular control is such, that it is impossible for the eye to focus sharply on near-by objects. Eyeglasses that are worn to correct this trouble are ground flat on one side and bulging outward on the other. The use of such a lens collects light from points on objects that are near by and projects them through the lens of the eye just as though they came from more distant objects. 9. If the defective vision is due to serious optical trouble there is no cure. Nearsighted people have a tendency to see distant objects more clearly as they grow older. Prolonged living in the outdoors with no close work for the eyes has a tendency to correct near- sightedness. 10. It is always better to use eyeglasses prop- erly ground to correct the vision to normal. ! Of course, on very fine type such as is found in older Bibles, encyclopedias, dictionaries, and so on, the use of a large-diameter read- ing glass frequently is helpful, in addition to the use of proper eyeglasses. A Well-Built House Is Cheapest (Continued from page 75) You may want to sell some day, and that’s one of the details that helps to hold value. Good plastering is another. You are going to use metal lath all over, but I’ve lately been specifying a kind that I like better than the ordinary varieties because it does more. It is welded wire mesh backed with some kind of sheeting which is much heavier than building paper, and behind which are stiffening ribs that keep it flat as a board. When the plaster goes on, the sheeting runs it together to form a solid slab with the wire in the center, and you get plaster walls that are reinforced and made air-tight by the sheeting.” ‘All of that sounds good to me,” said Bob. “ After hearing of Ed’s experiences I want my house to be as proof against grief as you can make it. But about that house that you saw where the piano went through the floor. The owner held the builder for it, didn’t he, and forced him to make good?” * E TRIED to, but he couldn’t. There’s no guarantee on a house, you know; you buy as is, and as soon as your name goes down on the dotted line you become responsible for it. There are builders who have enough pride in their work to make good when anything goes wrong, but they are the kind who put up houses that don’t give trouble. “It’s the same when you build. The work should be inspected as it goes along, to make sure that the specifications are being followed and that the workmanship is what it should be. If the builder is trying any funny business, that is the time to catch him; for if he puts something over and you don’t find it out until after you have accepted the job, it’s up to you. You can’t hold him.” “Well,” said Bob, “someone told me the other day that the soundness of a house de- pends on the honesty and moral worth of the builder, and what you say proves it.” “True enough,” the architect responded. “And that’s why you'll find me refusing to let you consider a bid from any contractor in whose personal good faith and reliability we have not full confidence.” DECEMBER, 1929 Demand for~ Skilled Mechanics ‘rhe entire country is calling for skill opneehanica! Good, pay-— steady work eu vancemen 1 fascinating trade with the aid of the . — a AMERICAN MACHINISTS’ LIBRARY 6 Volumes — 2,000 Pages — 2,500 Illustrations (A combined home-study course and reference library) This library of machine shop practice was written for practical men. It gives you the best methods for every kind of machine shop work. It explains machine tools and their operation, tool work, gears and grinding, jigs and fixtures, automatic screw machines, their too! Ss a. =. 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DeEcEMBER, 1929 High Speed Skyways | 14 Miles Up (Continued from page 27) ity theorist, approve the idea on theoretical grounds. As for putting it into practice, the | great Junkers airplane firm of Germany is now | tentatively planning super-airliners capable of navigating the upper air levels. These would have air-tight passenger cabins supplied with air at comfortably normal pressure, and super- charged motors to enable them to fly miles above the earth. Detailed designs for these craft are closely guarded. But a concrete picture of what a high-altitude plane would look like is given by B. V. Korvin-Kroukovsky, chief engineer of a College Point, N. Y., airplane firm. Its design, | he says, would be influenced by the two great- est problems of high-altitude flying—those of providing normally thick air for passengers, and of feeding normal air to the motor of the plane. BARREL-SHAPED cabin fuselage of duralumin, with air-tight joints, would be | the most radical feature of the 425-horsepower, five-passenger plane whose design he projects. To it air would be supplied at normal sea level pressure by a wind-driven compressor. Since theory would require a supercharger of im- practical size to supply compressed air to the motor, three or four superchargers of standard type would be used instead. These blowers would be run by the energy of the exhaust gas, as in certain standard supercharger types used today, notably that recently invented by Dr. S. A. Moss, of the General Electric Company. Another unusual feature of the high-flying craft would be a thirteen-foot, four-bladed propeller, its unusual size serving to obtain a grip on the extra-thin air. Such a craft, Korvin-Krou- kovsky declares, could navigate at a height of eleven miles or more above the earth, where the sky is probably almost black and the stars are plainly visible while the sun is shining. Its norma! speed would exceed 200 miles an hour. The possibility that airplanes might find free fuel at still greater heights is also suggested by this expert. At a height of about 35,000 feet, he estimates, the atmosphere begins to divide somewhat into layers, due to the difference in weight of the oxygen, nitrogen, and other gases of which it is a mixture. One of these gases is hydrogen, of which only a trace is found at the earth’s surface on account of its extreme light- ness. Colors of the polar lights show it abundant at high levels. At a height of about 200,000 feet the proportion of hydrogen to oxygen in the air probably is such that they | would burn with explosive violence, if the mixture were less rarefied. No doubt this is all that prevents a terrific celestial explosion whenever a flaming meteor falls through the hydrogen layer. PLANE capable of rising to 200,000 feet, Korvin-Kroukovsky estimates, could re- main aloft indefinitely by burning the com- pressed gas as fuel, and could travel anywhere at a speed of perhaps 3,000 miles an hour. But there is a catch in this happy possibility which is not soon to be solved—to reach such a height a plane would require forty times the minimum power it would use in flying at sea level. Such a power range is a remote aeronautical prospect. More nearly practical is the 75,000-foot altitude | plane with its supercharged gasoline engine and its air-tight cabin. “T believe that an airplane capable of reach- ing this height will be built within the very near future,’ Korvin-Kroukovsky declares. Recent medical studies show that not lack of oxygen alone, but the direct effect of the re- duced pressure of thin air, causes human dis- comfort at high altitudes. In this lies the reason for the “pressure cabin” proposed in all plans for high-altitude aircraft. Such a device may seem fanciful, (Continued on page 156) POPULAR SCIENCE MONTHLY created such a huge interestin; returning your sketch. and send it to us for FREE CRITICISM. Let us suena eee oseies _——e beg pp entirely to persons fourteen years o, and over. Age must be stated on your sketch. - OPPORTUNITIES ABOUND for Commercial Art- ists. No profession offers such unli today as may be found in Commercial Art a ing. The tremendous increase jn the use of illustrations in newspapers, magazines and national advertisements has demand for well-trained artists that ep ial Art and Illustrating is a real gold mine for the man or woman who likes to draw. : YOU CAN LEARN AT HOME —during your spare time — by our successful home-study correspondence method. No previous training necessary. Professional Artist’s Outfit gx ©. every student. Complete course in 25 fascinating lessons with PERSO ICISM of your individual drawings by our own staff of Commercial Artists. e pri y your own home--no ere you live or what you are now doing . You need this : sok. Fes can have ie ‘or the pate ues joes Place you under an; ‘wh e will send this book absolutely FREE when Kindly enclose 10c in stamps with your sketch to cover cost of mailing. \ North American School of Drawing, Inc. 403 McKinley Bidg. Sena skefch for free criticism 155 judge limited o ities Cartoon- asking. A Buffalo, N. 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156 POPULAR SCIENCE MONTHLY DEcEMBER, 1929 Campbell’s , . Deep High Speed Skyways . : 14 Miles : Infra-Red \ (4 . Penetrating sata ‘ 4 ' (Continued from page 156) | Ray Lamp ,* ’ \ Heat Lamp yet such a cabin was actually constructed for ' altitude flights, and tested a few years ago, by ' # the United States Army Air Corps. Only a SL , a ' minor defect in its mechanism prevented its : 4 : : ‘ further use. Write for a This steel chamber, barrel-shaped and prac- F Pe tically air-tight when its round, twenty-two-inch Bw acto ry ee, Me door was closed, was built into an altitude Pri ce plane at McCook Field, Dayton, O. A small id wind-driven compressor pumped air into it, and a relief valve above the pilot’s head could be oie) Days ta ee “ opened by hand to relieve the pressure at the pilot’s discretion. The device was given for Home . : 3 test to Lieut. John A. Macready, veteran T ri al f 4 altitude flyer then of the Army Air Corps. 4 ‘ It very nearly became his coffin. Macready squeezed through the narrow door into the barrel-shaped cabin, With a plate glass Let Me Send You This window in the door his only means of seeing the outside world, he took off. The plane Wonderful Lamp On Approval climbed a few hundred feet. Then to Mac- ready’s alarm his ears began to ring with Have you some troublesome ailment? The rays from this wonderful lamp penetrate pressure more intense than had been expected deeply into the body and generate a mild, soothing heat which quickly relieves con- He opened the relief valve. It could not let out gestion. If you relieve the congestion you will remove the trouble. Nature itself does the air as fast as the compressor was forcing it the healing. Here is the lamp that should be in every home. in. He tried to open the door, but the pressure ? , d was too great. The airman faced the novel Harmiless You can use the lamp anywhere on instant notice. Connect with terror of being blown up from the outside in. any electric light socket. It does not sunburn or blister. It is on an adjustable stand—easily carried to any room—adjustable to any position. Thou- HERE was no way of stopping the com- sands in use in homes. Leading health authorities recommend it for personal use. I bent which was driven by the wind out- Letters from satisfied users everywhere tell us wonderful results with its use. Let me side. Macready throttled the engine and send you this lamp on approval—use on thirty days’ trial. Just a few treatments coasted back toward the field as slowly as he will surprise you. First cost only cost. could to minimize the pump’s effect. He made ; , a rough-and-ready landing, and a second later Easy Payments Shipped by parcel post or express direct to you the pressure in the cabin went down auto- from factory at lowest cost. Easy payments enable matically with the stopping of the compressor. you to have this wonderful lamp at once. Don’t delay if you or some friend have some He was helped out none the worse for his ex- troublesome ailment. Write and let me send it at once. citing experience. The plane and its cabin were relegated to a museum. But, with a more Get Our Book On Infra-Red Rays | practical arrangement of valves, such a cabin might be adapted for future altitude airplanes. Quotes leading medical authorities and hundreds of users. Complete detailed infor- Its air-tight construction, incidentally, would mation of uses and benefits to be derived from Infra-Red Rays. keep an ocean plane afloat for hours or days in the event of a forced landing. WILLIAM CAMPBELL CO. Dept. 1041, ALLIANCE, OHIO Another possibility is an individual “pressure helmet” similar in appearance to a diver’s headgear, in which oxygen or air would be supplied to the pilot or passenger at sea level pressure when an airplane was flying at a great altitude. This device, suggested by Lieut. Apollo Soucek, Navy flyer and holder of the world’s seaplane altitude record, may be tried ' out by him in a future altitude attempt. TAMBURITZA More run—more friends— larger earnings—your long- ing to poy fulfilled. The TAMBURITZA helps you realize all this. You'll quickly master the simp'fied finger- All these proposals relate to the use of air- Pt, planes somewhat similar to those of con- YR *) ventional design to navigate the stratosphere. yy) But a future possibility suggested by some in- 1c MONEY, demonstrating and a selling AEROSTAT, first real improve- mentin carburetionin 20 years. Abso- lutelynew! Patented! Positively gives Ce a kK + 25% to50%moremileage! Saves car own- &y ow y? ventors is that of using rocket vehicles to ers hundreds o ions of gas! Entirely new re ° ized because they are 80 ens- principle, tested and approved by automo- > | navigate the stratosphere, the hydrogen and ”Tamburitss is a carefully tive engineers. An Amazing Seller! Guaran- /,{ 2 | other layers above, or even outer space itself to mice h-class Instrument has s wonderful tone that Seen ee are ee IOHEY NOW! U % | the moon and beyond. In defence of such a ry)—harmonizes in orchestrations. Ideal for schools, | FREE TRIAL! Zest Acrostatstour risk! % ~ visionary plan its supporters point out that a * Sendnomoney, just name Write today! chureh phy ees Te eiraotios chece free Wilt, | and address for Free Offer! rocket does not depend upon thin air, or any today for complete information. AEROSTAT MFG. CO. 25°2,Viuiet S* me 232 air at all, to propel and sustain it in flight. It Geupebues, Cite kicks itself along by the force of recoil of its own explosions, and would travel better in = ) > / 4 utterly empty space than in the atmosphere. ? a rockets were used for the start; three more gave Genuine ERECTOR Motor the machine the extra impetus that enabled it Thrilling Magazine Here's a genuine Erector Motor with driv- to leave the earth after a run of only thirty The rocket plane of forty-foot wing spread which Fritz Von Opel flew for a mile was The O; Road for B M i ing pulley. Runs mechanical toys like : has afty pages crammed with thrill. Erector, Meccano, ete. Uses dry battery seconds. Four that remained propelled the launched from a steel track. Two of the dozen ing stories of high adventure, sus- oF transformer. A wonderful, power~ 7, craft in flight. The pilot touched them off in se, mystery. Regular subseri tion ful little motor. Great for experi- $3 Price to The Open Road for Boys ments. With every motor is [Gee succession by electric wires. Gunpowder sup- Magazine is $1.00 a year. For $1.25 packed a 32 page experiment book } wo Ul cand Pou the’ mamasten ter a —UOEY Vabanben 2 plied the explosive kick of the rockets, though whole year and this electric motor. Almost given away. - Von Opel is experimenting with liquid explosive This is a great bargain. Order today. at, odel The Open Read fer Boys tomy Com ed 4 ry . boat ag lg ~ ie ennstuiiine: it al Department 88, 130 Newbury Street, Boston, Herman Oberth, an Austro-German, who re- 3. amt | ¥y cently announced that a thirty-three-foot cAmost GIVEN ANVA ’w model of a rocket (Continued on page 158) aS ————n — ———S— = ————— —--

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DeEcEMBER, 1929

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158 . « « the first Step Toward a Good Job i Architecture m eee eee fine positions and big salaries paid in Drafting, puting Construction and Architectura lin are leading many men to ask how they can “ in”. The sensible way is to learn Mechanical aie ay Seg | every man must know becomea Draftsman, or takecharge of construction jobs. You can easily learn Mechanical Drawing at home in 6 time— then you can get a job with some Contractor or Architect and cash in on it, while gaining valuable practical experience. Later on ae can tackle buildin superintendence, or architectura a, drafting, or contracts, estimates and specifications or some one other branch of the work. The new idea is to one “unit” of the 3 work at a time, as you need it for motion, and then make that training pay for tself before you take another. We'd like to tell you more about this new “‘one- step-at-a-time” me of training for a better job a raise, lower in cost and qui i Bey m5 courses”. Just mai American School RS ee. S Sith Se.» Chiange American School, Dept, D-548 Drexel A Chicago I am interested in the new quick may, t9 eet into Draft Contracting, Architecture, by starting with h drawing. Please send Free’ Uait’ Plan dook and complete information. Name... Address... the opportunities in that field, to- wi" our ¢.plan. Also be a e.’’ There is no cost or raen y- ees de eel deems and Independence. Check end nail the coupon NOW. ———==Find Yourself Through LaSalle =" ™ OBanking and Finance OModern BusinessCorre- OT, Ps] pa OCredit and Collection Name Present F: POPULAR SCIENCE MONTHLY DEcEMBER, 1929 car designed by him was to be built and tested at some point on the coast of the North or Baltic Sea. One use of such a rocket, he has claimed, would be to carry air mail across the Atlantic in thirty minutes. ‘The first model, a trial machine, was to be propelled by carbon shafts burning violently in liquid oxygen. He expressed the hope that it would reach an altitude of thirty miles or more above the earth. German naval authorities insisted that he point it out to sea, fearful of damage if it fell inland. Future models he planned, to be propelled by the exploding gases of liquid oxygen and benzene or alcohol, were a craft that would soar over and photograph unex- plored regions of the earth, and a 136-foot “space ship” for a flight to the moon. Commenting upon these projects and the flight of the powder-driven 1 rocket plane, Professor R. H. Goddard, of Clark Univer- sity, declares, “A plane equipped with powder rockets has an extremely limited cruising radius unless it is used as a rocket glider. If, on the contrary, liquid propellants are used, some surprising distances can be covered in a shorter time than with an ordinary plane.” Experiments with liquid explosives which Opel and Oberth have proposed are un- necessary, Professor Goddard says. His work under the Smithsonian Institution has already produced liquid-propellant rockets that work. A nine-foot trial model of a rocket of this kind which he designed nearly caused a ic when it soared over Worcester, Mass. PSM. Oct. 29, p. 24). One of Professor Goddard’s immediate and practical aims is to provide a device that can be sent aloft to a great height with weather instruments which will return at once, via parachute, and provide records to guide high-flying aviators. “Jet propulsion,” a novel form of power in which cool jets of gas at high pressure would have been designed to tell flyers their height above the ground by the time required for sound waves or radio waves to be reflected back from the earth to the airplane. At sea, the radio compass protects vessels from crashes and allows them to determine their position in a blinding fog. It indicates the direction of a radio signal, thus warning of the approach of other vessels moving through the fog, and giving the direction of points on land. A new invention in England enables the captain of a fog-bound boat to detect faint sounds of distant fog sirens as he edges towarc the shore. The device picks up the feeble sounds, amplifies them, and also converts them into light signals which appear as small light spots on a screen. Another phase of fog fighting is concerned with efforts to dispel the low-lying clouds. Two experiments in fog dispension conducted in recent years in America have given some promise of success. At the Government air- craft factory in Philadelphia, Pa., the Navy Bureau of Aeronautics conducted a series of ingenious demonstrations. Into a specially- constructed room, with brilliant lights shining on the wall opposite an observation window, were introduced clouds of man-made fog. The lights were all but obscured by the dense vapor. Suddenly a dozen jets sprayed highly electri- fied water into the room. The fog vanished as though by magic and the lights blazed forth as brilliantly as before. More spectacular was the performance of a “cloud eating airplane” which Dr. L. Francis Warren, of Harvard University, sent aloft at Bolling Field, Washington, D. C. some years ago. Equipped with tanks of fine silica sand and apparatus which charged the grains with | electricity as they were sprayed through a High Speed Skyways 14 Miles Up (Continued from page 156) First Victories in War on Fog (Continued from page 23) $$$. drive an airplane, offers still other future possibilities. So far it has not been applied to airplanes. But a jet-driven automobile in- vented by Max Valier, German aviator and experimenter with rockets, recently traveled thirty-seven miles an hour in a trial at Essen, Germany. Gas spurted with a hissing noise from three pressure tanks of steel, behind the driver’s seat, in which it was kept liquefied. Eventually airplanes, too, may use this form of power and soar to new heights. Whatever way airplanes may take to reach and navigate the stratosphere, it seems as if this will be the next great step forward in aviation. Sooner than most persons believe, airplanes may cross oceans in a few hours, and soar so high that powerful telescopes cannot discern them. Sunshine in Candy “@‘ANDIED sunshine” is the latest remedy for tuberculosis, anemia, and rickets. Two Viennese scientists claim to have found a way to irradiate chocolate with ultra-violet light in such a manner as to cause no loss or change in flavor. The investigators first experimented with rats, which increased in weight after eating the chocolate. - This result might, of course, also have been obtained with ordinary chocolate. More important and convincing, however, were tests with human patients, who are said to have improved in appetite and their blood after eating it. A process of irradiating cereals has been perfected in this country by Professor Harry Steenbock, of the University of Wisconsin. The inventor patented his process and then presented it to the University, which now licenses breakfast food manufacturers to use it on condition that they do not raise the price of their product. (P.S.M., Feb. ’29, p.47). nozzle, the machine climbed above a cumulus cloud. As it passed across the cloud, the trail of electrified sand ate a deep chasm in the fog. When the plane cut figure eights, the sand traced the evolution as easily as a blowtorch would eat its way through a snowbank. Then the pilot circled around and around, letting sand grains carve out a deep well in the mass of mist. From the bottom, the flyer said he could look up and see high white walls rising on all sides, with the blue sky far above. The secret, Dr. Warren explained, was that the electrical charges of the sand grains were opposite in polarity to those on the water particles in the fog. Instruments on the plane showed whether the cloud was charged positive- ly or negatively and the apparatus for spraying the sand could be set to give it an opposite charge. The water particles were attracted to the sand grains, forming large drops that fell as rain. This explanation also accounts for the disappearance of the fog in the laboratory room of the Bureau of Aeronautics, in Philadelphia. The electrified water particles sprayed into the room attracted the fog droplets having charges of the opposite sort of electricity. “Cloud-eating” airplanes have demonstrated effectiveness on a small scale. Whether they will be of practical value over large areas only additional and costly tests can answer. The machines used at Bolling Field spread only thirty pounds of sand a minute. Dr. Warren declares that two or more planes capable of spreading 1,100 pounds a minute could dispel fog over an area the size of London. Since the airplane has taken its place as a recognized means of transportation, the prob- lem of conquering fog assumes new importance. Whoever can find the key to controlling it will be ranked with the great servants of mankind.

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DeEcEMBER, 1929 POPULAR SCIENCE MONTHLY » THESE DIAGRAMS TELL ALL THERE IS TO KNOW ABOUT “B” BATTERIES « ° matically. Only five solderings, only two broad connecting a Maxi- mum reliability, maximum active materials, greatest life. Layerbilt con- struction is an exclusive Eveready feature. Only Eveready makes Layer- bilt Batteries. IN VITAL SERVICES Eveready Batteries are being used in automatic train con- trol, aircraft beacon receivers, talking motion pictures, short wave transmission, picture transmission, television; for the protection of life and property and to secure instant, unfailing, noiseless, perfect electrical power. This is the LARGE SIZE Eveready Layerbilt “‘B’”’ Battery for heavy duty, No. 486, the longest lasting, most economical of all Evereadys. Price $4.25. There is also another Eveready Layerbilt, Medium Size, No. 485, at $2.95. EVEREADY LAYERBILT CONSTRUCTION—Here is the inside story of the Eveready Layerbilt—flat, space-saving cells CYLINDRICAL CELL CONSTRUCTION—dHere is the inside story about cells——29 auto- every “‘B’”’ battery assembled of separate, individually fine connecting wires, 60 solderings, and lots of waste space between cells. HERE are revealed the inside facts about “B” batteries, to guide you in selecting the ones that will give you the most for your money. One diagram shows the old cylindrical cell type of battery. Note the 29 fine wires, and the 60 delicate solderings—89 places where trouble can come. We make such batteries as well as they can be made, but we also make a much better kind—the unique Eveready Layerbilt. See the Eveready Layerbilt diagram. Note the flat cells of which it is built. Those cells are not independent, needing soldered connections, but interdependent, making connection with each other automatically. To join the two sections, but two broad connecting bands are needed, each 3 inch wide. There are but five husky, trouble-proof solderings. And to cap the climax, the flat cells pack more active materials within the battery, and so you get longer life, greater convenience and economy. Eveready Layerbilts are the best batteries made, and no other battery is like them. You can make “B” batteries out of separate cells of any shape you choose, and still you cannot imitate the Eveready Layerbilt. It is patented, and exclusive with us; our invention, and your advantage in economy, convenience and satisfaction. Be sure you get Eveready Layerbilts. Look for the name printed large on the label. NATIONAL CARBON COMPANY, INC. General Offices, New York, N. Y. Branches: Chicago Kansas City New York San Francisco Unit of Union Carbide UCC and Carbon Corporation TUESDAY NIGHT IS EVEREADY HOUR NIGHT—East of the Rockies—9 P.M. Eastern Standard Time, through WEAF and associated N. B.C. stations NEW EVEREADY RADIO RECEIVERS ... A.C. AND BATTERY OPERATED ... NOW ON SALE @ 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 LOOKING INSIDE A CLOSED CYLINDER The Midgley Indicator ETHYL © E. G. C. 1929 D+4=@ [es Knocks out that “knock” GASOLINE there famous Midgley Indicator was devised to enable the scientists in General Motors Research Laboratories to look inside the closed cylinder of a gasoline engine. It tells exactly what happens in that tiny fraction of a second when gasoline explodes. The Midgley Indicator is an ingenious and sénsi- tive mechanism which records the pressure inside the cylinder while the engine is running. By studying these pressures the scientists found out exactly what caused an engine to “knock.” In fact, they found it was not theengine at all, but the fue/ which “knocks.” Gasoline—even the best, they found—explodes too fast when compressed beyond certain limits. So they developed Ethyl fluid, whose active ingredient is tetraethyl lead, which controls the combustion rate of gasoline under increased pressures. Ethyl Gasoline—good gasoline to which Ethyl fluid has been added—has created a new standard of motoring efficiency and comfort. It has made pos- sible the new so-called “high compression” cars, and it improves the performance of older cars. Try Ethyl in your car. You'll see the difference. Ethyl Gasoline Corporation, 25 Broadway, New York City; 56 Church Street, Toronto, Can.; 36 Queen Anne’s Gate, London, England. NELLEY & SONS CO., CHICAGO DEcEMBER, 1929

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Tell ‘em y

ILBER OYS,. here’s your chance to give Mother and Dad the surprise of their lives! Build with your own hands furniture, airplanes, toys, bird houses, and hundreds of other practical things—just like skillful builders do. Tell Dad you want to join the group of real fellows who build things with Gilbert “Big Boy’’ tools. Tell him today you'll start right in as soon as you get your Big Boy Set. Lift the lid of one of my big red brass-bound tool chests and you open up a whole new world of excit- ing thrills. Put on the sporty carpenter's apron, call in your pals and show them how a real builder goes to work. Oh, Boy! How their eyes will pop! My Boy Builder’s Plan Book tells exactly how each job is done. ‘ ¢ I know what you need and I’ve built these tools especially for you. . Find out right away how smart you are with your hands. Look over my Big Boy Tool Chests and machine shop outfits at any good store. Take Dad along. Tell him you want to be a full-fledged member of this happy group of builders. Pick out your set, And there’s a tool for every purpose. getit home quickly, and start right in building wonderful things. See that you get these Feature Tools.

Let’s Go If you want to make things hum, the thing for you is my brand new Motor-Driven Machine Shop, the greatest thing I’ve made for boys since I invented Erector. Yes sir, it’s a complete scientific work shop for the amateur—a combination portable lathe, demountable drill, emery wheel for grinding knives and sharpening tools. There’s a real scratch brush for removing rough surfaces from metal, and a buffing wheel for finishing and polishing metal And—Boy, here’s news—this workshop’s equipped with a 4%-H.P. Universal Motor and A.C. or D.C., with toggle switch, cord and plug. It would take a whole page to tell you everything about this marvelous outfit. Send that coupon in to me and get the booklet that tells you all in words and pictures. Boys This big chest of tools (Number 780) is the treasured possession of thousands of red-blooded boys. They wouldn’t swap it for a million dollars. But you can get yours at any good store. There are 26 pieces in all—18 pounds of scien- tific fun—the kind of fun you'll never get tired of. A saw that bites its way through wood, a plane that shaves like a master, a brace and bit, chisels and dozens of other he- man tools for the boy builder. And two complete books that show clearly and exactly how to build hundreds of wonderful useful things. Now boys, be sure you get my big red brass-bound BIG BOY Tool Chest, because I know what you need and have spent ten years planning this fun for you. The New 1929 Line Includes These Important Desirable Features When you are looking for a Chest of Tools, be sure you get these big exclusive features contained in the Dad’s Size Chests. SCRIND Wen - Big Boy Saws. 10. Metal Tray. 11. Big red brass bound chest. Big Boy Tool Chests have more tools than other chests at the price. All metal spirit level in No. 785 and up. Ground faced block plane in No. 765 and No. 780. Bench plane, in No. 785 and up. Sapolin color chart, Home Manual, Plan Book and Sapolin Speed Enamel, in all Dad’s Size chests. New 1929 Plan Book in all sets. Carpenter’s apron in No. 785 and up. Drop forged hammers in Dad’s Size chests. THE A. C. GILBERT COMPANY, New Haven, Conn., U.S.A. Manufacturers of the Famous Erector and Chemistry Sets, Magic, Motors, Etc A. C. Gilbert’s Radio Sports Talks. See station listings—page 101 Hello hoys/ 1 a ou butt it with A

A. C. GILBERT’S FREE PLAN BOOK If you want to know all about the 1929 Big Boy Tool Chests, send for your copy of my Plan Book, which tells how to construct dozens of interesting things, including Toys, Bird Houses, Household Utilities, Boats, Ete. PLAN BOOK and catalog describing var- ious Big Boy Tool Chests come to your door free for the ask- ing. Just fill out the little coupon below by writing your name and address, and mail the coupon today. 1o-k “Built for Boys’’ oy Tools

GILBERT Big-Boy” Tool Chests DAD’S SIZE Household Treasure Chest No. 780. 26 pieces of he-man tools including big 16-inch cross cut saw and 7 %-in. plane. A regular outfit. Two plan books and color chart. Packed in brass bound chest. Sapolin Speed pe re rere The Master Carpenter Set No. 785. Practical selected tools. 33 pieces, 2 plan books and color chart, 15-in. steel level, 16-in. cross cut and dandy keyhole saw, also 9-in. plane. Packed in brass bound chest. Sapolin Speed ere The DeLuxe Carpenter Set No. 790. Feature set of Big Boy line. 37 ieces including 9-in. plane, ratchet race, 15-in. level, 20-in. cross, 18- in. rip, and dandy keyhole saws. 2 plan books and color chart. Packed in big red chest, brass corners and lock. Sapolin Speed Enamel. . $25.00 BOY’S SIZE Little Fellow’s Set No. 701. Con- tains 11 pieces with plan book. $1.00 Dandy Big Set No. 701E. The set for the beginner. Contains 12 pieces With IAG DOG. . i6n 5 d05s 000% $1.50 Practical Young Carpenter’s Set o. 16 pieces with plan WOU: Sckntx doa 4-doban< vider $2.50 Handy Set No. 707 . Practical set for boys, 19 pieces including plan OU tisacdancs sudan ee eaeae $3.50 Famous No. 765. Feature set in Boy’s Size group. Dandy Set. 24 pieces. Packed in big red chest with ‘plan ee EO Fre $5.00

THE A. C. Gr_pert COMPANY 98 ERECTOR SQUARE New Haven, Conn. Please send me free copy of Plan Book eeegceeeccceseensseeesrsvescessencssedesqerssbearsrseeesrersneseeeeee and Gilbert Toy Catalog.

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| ey, The cheer leader—_ ° (‘amel CI@ARETTES More genuine pleasure... more hearty cheer... Camel gains on every play. Go into a huddle with yourself and a pack of Camels... and yow’re all set. © 1929, R. J. Reynolds Tobacco et f Company, Winston-Salem, N. C. ——

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